Name: a photodynamic approach to study function of intracellular vesicle rupture
Uploaded: 2023-03-17T14:45:00
Description: Watch this Scientific Journal Video about A Photodynamic Approach to Study Function of Intracellular Vesicle Rupture at JoVE.com

The authors wish to thank the Academia Sinica Inflammation Core Facility, IBMS for research support. The core facility is funded by the Academia Sinica Core Facility and Innovative Instrument Project (AS-CFII-111-213). The authors thank the Common Equipment Core Facility of the Institute of Biomedical Sciences (IBMS), Academia Sinica (AS) for assisting the image acquisition.

1. AlPcS2a stock preparation
<ol>
	<li>Dissolve 10 mg of AlPcS2a in 400 &#181;L of 0.1 M NaOH. To improve solubility, heat the solution at 50 &#176;C and vortex.</li>
	<li>Mix the solution with 4 mL of phosphate-buffered saline (PBS). Then, filter the solution with a 0.22 &#181;m filter to remove the insoluble precipitates.</li>
	<li>Measure the concentration of the solution through a UV-Vis spectrophotometer. The extinction coefficient of AlPcS2a at 672 nm is 4 x 10<su...

<ol>
	<li>Cossart, P., Helenius, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Endocytosis+of+viruses+and+bacteria.">Endocytosis of viruses and bacteria.</a> Cold Spring Harbor Perspectives in Biology. 6 (8), 016972 (2014).</li><li>Daussy, C. F., Wodrich, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=34;Repair+me+if+you+can&amp;#34;:+membrane+damage,+response,+and+control+from+the+viral+perspective.">34;Repair me if you can&amp;#34;: membrane damage, response, and control from the viral perspective.</a> Cells. 9 (9), 2042 (2020).</li><li>Hung, Y. H., Chen, L. M., Yang, J. Y., Yang, W. Y. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Spatiotemporally+controlled+induction+of+autophagy-mediated+lysosome+turnover.">Spatiotemporally controlled induction of autophagy-mediated lysosome turnover.</a> Nature Communications. 4, 2111 (2013).</li><li>Sharma, S. K., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Photodynamic+therapy+for+cancer+and+for+infections:+what+is+the+difference.">Photodynamic therapy for cancer and for infections: what is the difference.</a> Israel Journal of Chemistry. 52 (8-9), 691-705 (2012).</li><li>K&#252;bler, A. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Photodynamic+therapy.">Photodynamic therapy.</a> Medical Laser Application. 20 (1), 37-45 (2005).</li><li>De Rosa, F. S., Bentley, M. V. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Photodynamic+therapy+of+skin+cancers:+sensitizers,+clinical+studies+and+future+directives.">Photodynamic therapy of skin cancers: sensitizers, clinical studies and future directives.</a> Pharmaceutical Research. 17 (12), 1447-1455 (2000).</li><li>Hamblin, M. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=New+photosensitizers+for+photodynamic+therapy.">New photosensitizers for photodynamic therapy.</a> Biochemical Journal. 473 (4), 347-364 (2016).</li><li>Lavie, G., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+photodynamic+pathway+to+apoptosis+and+necrosis+induced+by+dimethyl+tetrahydroxyhelianthrone+and+hypericin+in+leukaemic+cells:+possible+relevance+to+photodynamic+therapy.">A photodynamic pathway to apoptosis and necrosis induced by dimethyl tetrahydroxyhelianthrone and hypericin in leukaemic cells: possible relevance to photodynamic therapy.</a> British Journal of Cancer. 79 (3-4), 423-432 (1999).</li><li>Jay, D. G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Selective+destruction+of+protein+function+by+chromophore-assisted+laser+inactivation.">Selective destruction of protein function by chromophore-assisted laser inactivation.</a> Proceedings of the National Academy of Sciences. 85 (15), 5454-5458 (1988).</li><li>Grate, D., Wilson, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Laser-mediated,+site-specific+inactivation+of+RNA+transcripts.">Laser-mediated, site-specific inactivation of RNA transcripts.</a> Proceedings of the National Academy of Sciences. 96 (11), 6131-6136 (1999).</li><li>Lin, J. Y., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Optogenetic+inhibition+of+synaptic+release+with+chromophore-assisted+light+inactivation+(CALI).">Optogenetic inhibition of synaptic release with chromophore-assisted light inactivation (CALI).</a> Neuron. 79 (2), 241-253 (2013).</li><li>Hsieh, C. W., Yang, W. Y. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Triggering+mitophagy+with+photosensitizers.">Triggering mitophagy with photosensitizers.</a> Methods in Molecular Biology. 1880, 611-619 (2019).</li><li>Yang, J. Y., Yang, W. Y. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Spatiotemporally+controlled+initiation+of+Parkin-mediated+mitophagy+within+single+cells.">Spatiotemporally controlled initiation of Parkin-mediated mitophagy within single cells.</a> Autophagy. 7 (10), 1230-1238 (2011).</li><li>Molinari, M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Vacuoles+induced+by+Helicobacter+pylori+toxin+contain+both+late+endosomal+and+lysosomal+markers.">Vacuoles induced by Helicobacter pylori toxin contain both late endosomal and lysosomal markers.</a> Journal of Biological Chemistry. 272 (40), 25339-25344 (1997).</li><li>Prince, L. R., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Subversion+of+a+lysosomal+pathway+regulating+neutrophil+apoptosis+by+a+major+bacterial+toxin,+pyocyanin.">Subversion of a lysosomal pathway regulating neutrophil apoptosis by a major bacterial toxin, pyocyanin.</a> Journal of Immunology. 180 (5), 3502-3511 (2008).</li><li>Aits, S., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Sensitive+detection+of+lysosomal+membrane+permeabilization+by+lysosomal+galectin+puncta+assay.">Sensitive detection of lysosomal membrane permeabilization by lysosomal galectin puncta assay.</a> Autophagy. 11 (8), 1408-1424 (2015).</li><li>Prasmickaite, L., Hogset, A., Berg, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Evaluation+of+different+photosensitizers+for+use+in+photochemical+gene+transfection.">Evaluation of different photosensitizers for use in photochemical gene transfection.</a> Photochemistry and Photobiology. 73 (4), 388-395 (2001).</li><li>Berg, K., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Photochemical+internalization:+a+novel+technology+for+delivery+of+macromolecules+into+cytosol.">Photochemical internalization: a novel technology for delivery of macromolecules into cytosol.</a> Cancer Research. 59 (6), 1180-1183 (1999).</li><li>Moan, J., Berg, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+photodegradation+of+porphyrins+in+cells+can+be+used+to+estimate+the+lifetime+of+singlet+oxygen.">The photodegradation of porphyrins in cells can be used to estimate the lifetime of singlet oxygen.</a> Photochemistry and Photobiology. 53 (4), 549-553 (1991).</li><li>Thurston, T. L., Wandel, M. P., von Muhlinen, N., Foeglein, A., Randow, F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Galectin+8+targets+damaged+vesicles+for+autophagy+to+defend+cells+against+bacterial+invasion.">Galectin 8 targets damaged vesicles for autophagy to defend cells against bacterial invasion.</a> Nature. 482 (7385), 414-418 (2012).</li><li>Repnik, U., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=L-leucyl-L-leucine+methyl+ester+does+not+release+cysteine+cathepsins+to+the+cytosol+but+inactivates+them+in+transiently+permeabilized+lysosomes.">L-leucyl-L-leucine methyl ester does not release cysteine cathepsins to the cytosol but inactivates them in transiently permeabilized lysosomes.</a> Journal of Cell Science. 130 (18), 3124-3140 (2017).</li><li>Griffiths, G., Hoflack, B., Simons, K., Mellman, I., Kornfeld, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+mannose+6-phosphate+receptor+and+the+biogenesis+of+lysosomes.">The mannose 6-phosphate receptor and the biogenesis of lysosomes.</a> Cell. 52 (3), 329-341 (1988).</li><li>Jia, J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Galectin-3+Coordinates+a+cellular+system+for+lysosomal+repair+and+removal.">Galectin-3 Coordinates a cellular system for lysosomal repair and removal.</a> Developmental Cell. 52 (1), 69-87 (2020).</li><li>Chu, Y. P., Hung, Y. H., Chang, H. Y., Yang, W. Y. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Assays+to+monitor+lysophagy.">Assays to monitor lysophagy.</a> Methods in Enzymology. 588, 231-244 (2017).</li><li>Nguyen, L., Madsen, S. J., Berg, K., Hirschberg, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=An+improved+in+vitro+photochemical+internalization+protocol+for+3D+spheroid+cultures.">An improved in vitro photochemical internalization protocol for 3D spheroid cultures.</a> Lasers in Medical Science. 36 (8), 1567-1571 (2021).</li><li>Daugelaviciene, N., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Lysosome-targeted+photodynamic+treatment+induces+primary+keratinocyte+differentiation.">Lysosome-targeted photodynamic treatment induces primary keratinocyte differentiation.</a> Journal of Photochemistry and Photobiology. B, Biology. 218, 112183 (2021).</li><li>Hong, M. H., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Intracellular+galectins+control+cellular+responses+commensurate+with+cell+surface+carbohydrate+composition.">Intracellular galectins control cellular responses commensurate with cell surface carbohydrate composition.</a> Glycobiology. 30 (1), 49-57 (2019).</li></ol>

AlPcS2a binds to the plasma membrane, then is internalized by endocytosis and eventually accumulates in lysosomes. AlPcS2a can thus be localized in the subcellular compartments by adjusting the incubation duration. A limitation of this methodology is that only a sub-population of IVs could be labeled by AlPcS2a through endocytosis because there are many other membrane sources of IVs, such as ER and Golgi apparatus. In addition, the selective labeling of AlPcS2a into early or la...

Endosomes, a type of intracellular vesicle (IV), are formed by endocytosis and then mature into lysosomes. Various intracellular signal pathways are involved in the formation of IVs; additionally, different intrinsic and extrinsic stimuli can damage IVs (e.g., pathogens can escape from the bounded membrane during infection and enter into cytoplasm1). This is usually accompanied by the rupture of endocytotic vesicles2. Therefore, the techniques for targeting and damaging IVs can be used in related studies3.
Photodynamic therapy (PDT) is a light-dependent therapy to combat diseases by killing tumors or pathogens4. In PDT, targeted cells are labeled with non-toxic chromophores, called photosensitizers, that can be locally activated by light illumination5,6. Photosensitizers absorb energy from light and transform into an excited singlet state, leading to the long-lived excited triplet state. Photosensitizers of the triplet state can undergo electron or energy transfer and form reactive oxygen species (ROS) in the presence of oxygen, and can spatially destroy labeled cells within the illumination region7. The consequence varies depending on the power of light8. By controlling the concentration of photosensitizers and the intensity of light illumination, targeted biomolecules can be selectively inactivated without cell lysis, termed as chromophore-assisted light inactivation (CALI)9. With the significant development of photosensitizers that can selectively label various subcellular targets, CALI has become a valuable tool to control light-mediated inactivation of biomolecules for small biomolecules such as nucleotides and proteins, as well as organelles such as mitochondria and endo-lysosomes3,10,11,12,13.
Compared to CALI, chemical or physical methods are also used to impair membranes, such as bacterial toxin14,15 and Leu-Leu-OMe16 treatment for lysosomal damage. However, these methods display bulk impairment of IVs within cells. Robust photosensitizers (i.e., Al(III) phthalocyanine chloride disulfonic acid (AlPcS2a)) are used in CALI; AlPcS2a, targeting the lysosomes through endocytosis, is used to rupture endosomes or lysosomes in a controlled region17. AlPcS2a is a cell membrane-impermeable phthalocyanine-based chromophore that binds to lipid on plasma membrane and is internalized through endocytosis and eventually accumulates within the lysosome through the endocytic pathway18. It absorbs light within a near-infrared spectral region and generates singlet oxygen, a major ROS generated by excited AlPcS2a18. Singlet oxygen decaying rapidly limits its diffusion and reaction distance within a tiny region in cells (approximately 10-20 nm)19. By adjusting the duration of AlPcS2a incubation and light illumination, spatiotemporal control of the damage of IVs within a subcellular area is allowed. CALI therefore becomes a powerful tool for examining the consequences of IV damage, and the formation and regulation of IVs.
In this study, a specific protocol of CALI using AlPcS2a as a photosensitizer is addressed. This protocol can be applied to various types of IVs, including endosomes and lysosomes, and used to examine the follow-up responses after membrane rupture. HeLa cells expressing fluorophore-conjugated galectin-316,20 revealed after lysosome rupture are used to demonstrate this protocol.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>Reagent</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Al(III) Phthalocyanine Chloride Disulfonic acid (AlPcS2a)</td>
			<td>Frontier Scientific</td>
			<td>P40632</td>
			<td></td>
		</tr>
		<tr>
			<td>Culture dish</td>
			<td>ibidi</td>
			<td>812128-200</td>
			<td></td>
		</tr>
		<tr>
			<td>Culture Medium</td>
			<td></td>
			<td></td>
			<td>DMEM supplemented with 10% FBS and 100 U/mL penicillin G and 100 mg/mL Streptomycin</td>
		</tr>
		<tr>
			<td>DMEM</td>
			<td>Gibco</td>
			<td>11965092</td>
			<td></td>
		</tr>
		<tr>
			<td>FBS</td>
			<td>Thermo Fisher Scientific</td>
			<td>A4736301</td>
			<td></td>
		</tr>
		<tr>
			<td>Gal3-GFP plasmid</td>
			<td>addgene</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Lipofectamine 3000 kit</td>
			<td>Thermo Fisher Scientific</td>
			<td>L3000008</td>
			<td></td>
		</tr>
		<tr>
			<td>LysoTracker Green DND-26</td>
			<td>Thermo Fisher Scientific</td>
			<td>L7526</td>
			<td>green fluorescent dye</td>
		</tr>
		<tr>
			<td>Multiwall plate</td>
			<td>perkinelmer</td>
			<td>PK-6005550</td>
			<td></td>
		</tr>
		<tr>
			<td>NaOH</td>
			<td>Thermo Fisher Scientific</td>
			<td>Q15895</td>
			<td></td>
		</tr>
		<tr>
			<td>OptiMEM</td>
			<td>Thermo Fisher Scientific</td>
			<td>31985070</td>
			<td></td>
		</tr>
		<tr>
			<td>Penicillin-streptomycin</td>
			<td>Gibco</td>
			<td>15140163</td>
			<td></td>
		</tr>
		<tr>
			<td>Phosphate-Buffered Saline (PBS)</td>
			<td>Gibco</td>
			<td>21600-069</td>
			<td>137 mM NaCl, 2.7 mM KCl, 10mM Na2HPO4, 1.8 mM KH2PO4</td>
		</tr>
		<tr>
			<td>Cell line</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>HeLa Cell Line</td>
			<td>ATCC</td>
			<td>CCL-2</td>
			<td>The methods are applicable for most of the attached cell lines. Conditions must be determined individually.</td>
		</tr>
		<tr>
			<td>Equipments</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>0.22 &#181;m Filter</td>
			<td>Merck</td>
			<td>SLGV013SL</td>
			<td></td>
		</tr>
		<tr>
			<td>Collimated LED Light&#160; (660nm)</td>
			<td>Thorlabs</td>
			<td>M660L3-C1 and DC2100</td>
			<td>Near-infared light is ideal base on the excitation spectrum of AlPcS2a.</td>
		</tr>
		<tr>
			<td>Confocal microscopy</td>
			<td>Carl Zeiss</td>
			<td>LSM 780</td>
			<td>An incubation system is required for long-term imaging.</td>
		</tr>
		<tr>
			<td>NanoDrop 2000/2000c Spectrophotometers</td>
			<td>Thermo Fisher Scientific</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Red LED light</td>
			<td>Tholabs</td>
			<td>M660L4-C1</td>
			<td></td>
		</tr>
	</tbody>
</table>

a photodynamic approach to study function of intracellular vesicle rupture

Intracellular vesicles (IVs) are formed through endocytosis of vesicles into cytoplasm. IV formation is involved in activating various signal pathways through permeabilization of IV membranes and the formation of endosomes and lysosomes. A method named chromophore-assisted laser inactivation (CALI) is applied to study the formation of IVs and the materials in controlling IV regulation. CALI is an imaging-based photodynamic methodology to study the signaling pathway induced by membrane permeabilization. The method allows spatiotemporal manipulation of the selected organelle to be permeabilized in a cell. The CALI method has been applied to observe and monitor specific molecules through the permeabilization of endosomes and lysosomes. The membrane rupture of IVs is known to selectively recruit glycan-binding proteins, such as galectin-3. Here, the protocol describes the induction of IV rupture by AlPcS2a and the use of galectin-3 as a marker to label impaired lysosomes, which is useful in studying the downstream effects of IV membrane rupture and their downstream effects under various situations.

A schematic figure representing the AlPcS2a-induced damage of IV, including endosome and lysosome, has been shown (Figure 1).
Commercially available markers can be used to determine the AlPcS2a staining conditions. For example, AlPcS2a puncta and green fluorescent dye22 colocalization (Figure 2).
Fluorophore-labeled galectin-3 can be applied as an ind...

Watch this Scientific Journal Video about A Photodynamic Approach to Study Function of Intracellular Vesicle Rupture at JoVE.com

A Photodynamic Approach to Study Function of Intracellular Vesicle Rupture

AlPcS2a-mediated chromophore-assisted laser inactivation (CALI) is a powerful tool for studying spatiotemporal damage of intracellular vesicles (IVs) in live cells.

Intracellular vesicles (IVs) are formed through endocytosis of vesicles into cytoplasm. IV formation is involved in activating various signal pathways ...

Endocytosis of vesicle into cytoplasia results in the formation of intracellular vesicles. Permeabilization of vesicle activates various signal pathways. Chromophore-assisted laser inactivation is used to study the consequence of intracellular vesicle rupture.A spatial and temporal control of subcellular damage to intracellular vesicles can be achieved by adjusting the standing condition and light illumination. To begin, maintain HeLa cell culture in DMEM supplemented with 10%FBS. After washing the cells with PBS, Trypsinize the cells.Then resuspend the cells in DMEM supplemented with 10%FBS. Dilute 300 nanograms of Gal3-GFP plasmid in 25 microliters of reduced serum medium. Then add 0.6 microliters P3000 reagent.And gently mix, followed by vortexing the solution. Dilute 0.45 microliters of Lipofectamine 3000 reagent in 25 microliters of reduced serum medium and gently mix. Incubate for five minutes at room temperature.Then mix diluted DNA and diluted Lipofectamine 3000 and incubate for 10 minutes at room temperature. After mixing the DNA lipofectamine mixture, 300, 000 suspended HeLa cells and 200 microliters of DMEM with 10%FBS, seed the cells on the central glass region of a 35-millimeter glass button dish. To allow cell attachment, incubate the cells at 37 degrees Celsius in the incubator supplied with 5%carbon dioxide for at least four hours.Dilute AlPcS2a in DMEM supplemented with 10%FBS to make a one micromolar AlPcS2a solution. Prewarm the AlPcS2a containing-medium in a 37 degrees Celsius water bath and replace the culture medium with the AlPcS2a-containing medium. Incubate the cells at 37 degrees Celsius in the incubator supplied with 5%carbon dioxide overnight.The following day, wash the cells twice with PBS to remove extracellular AlPcS2a after replacing the medium with fresh medium. Incubate at 37 degrees Celsius for four hours to allow residual dye along the endocytic pathway to accumulate into lysosomes. To manipulate single cells by damaging lysosomes, place the culture dish on the stage of a confocal microscope.Use the 488 nanometer and 561 nanometer lasers for exciting GFP and AlPcS2a, respectively. Circle a five-by-five micrometer square region of interest on the AlPcS2a labeled vesicles which are selected to be damaged. Then pulse illuminate the region of interest with a 633 nanometer laser of 0.21 milliwatt, or 70 repeats.Monitor the formation of Gal3 puncta as an indicator of lysosomal membrane permeabilization. Lysosomal staining with AlPcS2a in HeLa cells was performed using commercially-available markers, and were positively stained with green fluorescent dye. Lysosomes in TagRFP-Galectin3 expressed HeLa cells were stained with AlPcS2a.Followed by focusing illumination with near infrared light, the results indicate that AlPcS2a-based chromophore-assisted laser inactivation was able to control local lysosomal rupture within the region of interest, leaving the rest of the lysosomes intact. This step is important because the incubation time will determine standing endosomes or lysosomes. For example, people can determine the size of by the release of membrane-impermeable dye.Also can use pH sensitive dyes such as FITC dextran to difference endosomes and lysosomes. This technique is useful starting the downstream effects of intracellular vesicle membrane rupture. And there are downstream effects under various situations.

a-photodynamic-approach-to-study-function-intracellular-vesicle

Research

JoVE Journal

Immunology and Infection

Single Cell Measurements of Vacuolar Rupture Caused by Intracellular Pathogens

Shigella flexneri are pathogenic bacteria that invade host cells entering into an endocytic vacuole. Subsequently, the rupture of this membrane-enclosed compartment allows bacteria to move within the cytosol, proliferate and further invade neighboring cells. Mycobacterium tuberculosis is phagocytosed by immune cells, and has recently been shown to rupture phagosomal membrane in macrophages. We developed a robust assay for tracking phagosomal membrane disruption after host cell entry of Shigella flexneri or Mycobacterium tuberculosis. The approach makes use of CCF4, a FRET reporter sensitive to &beta;-lactamase that equilibrates in the cytosol of host cells. Upon invasion of host cells by bacterial pathogens, the probe remains intact as long as the bacteria reside in membrane-enclosed compartments. After disruption of the vacuole, &beta;-lactamase activity on the surface of the intracellular pathogen cleaves CCF4 instantly leading to a loss of FRET signal and switching its emission spectrum. This robust ratiometric assay yields accurate information about the timing of vacuolar rupture induced by the invading bacteria, and it can be coupled to automated microscopy and image processing by specialized algorithms for the detection of the emission signals of the FRET donor and acceptor. Further, it allows investigating the dynamics of vacuolar disruption elicited by intracellular bacteria in real time in single cells. Finally, it is perfectly suited for high-throughput analysis with a spatio-temporal resolution exceeding previous methods. Here, we provide the experimental details of exemplary protocols for the CCF4 vacuolar rupture assay on HeLa cells and THP-1 macrophages for time-lapse experiments or end points experiments using Shigella flexneri as well as multiple mycobacterial strains such as Mycobacterium marinum, Mycobacterium bovis, and Mycobacterium tuberculosis.

We describe a method for tracking the endomembrane rupture elicited by the intracellular bacteria Shigella flexneri and Mycobacterium tuberculosis upon host cell invasion. Our assay makes use of CCF4, a host cytoplasmic FRET probe in live or fixed cells. This reporter is degraded by an enzyme activity present on the bacterial surface.

Shigella flexneri are pathogenic bacteria that invade host cells entering into an endocytic vacuole. Subsequently, the rupture of this membrane-enclosed ...

Establishment of an In vitro System to Study Intracellular Behavior of Candida glabrata in Human THP-1 Macrophages

A cell culture model system, if a close mimic of host environmental conditions, can serve as an inexpensive, reproducible and easily manipulatable alternative to animal model systems for the study of a specific step of microbial pathogen infection. A human monocytic cell line THP-1 which, upon phorbol ester treatment, is differentiated into macrophages, has previously been used to study virulence strategies of many intracellular pathogens including Mycobacterium tuberculosis. Here, we discuss a protocol to enact an in vitro cell culture model system using THP-1 macrophages to delineate the interaction of an opportunistic human yeast pathogen Candida glabrata with host phagocytic cells. This model system is simple, fast, amenable to high-throughput mutant screens, and requires no sophisticated equipment. A typical THP-1 macrophage infection experiment takes approximately 24 hr with an additional 24-48 hr to allow recovered intracellular yeast to grow on rich medium for colony forming unit-based viability analysis. Like other in vitro model systems, a possible limitation of this approach is difficulty in extrapolating the results obtained to a highly complex immune cell circuitry existing in the human host. However, despite this, the current protocol is very useful to elucidate the strategies that a fungal pathogen may employ to evade/counteract antimicrobial response and survive, adapt, and proliferate in the nutrient-poor environment of host immune cells.

Establishment of an In vitro System to Study Intracellular Behavior of Candida glabrata in Human THP-1 Macrophages

The current article outlines a protocol to establish an in vitro cell culture model system to study the interaction of a facultative intracellular human fungal pathogen Candida glabrata with human macrophages which will be a useful tool to advance our knowledge of fungal virulence mechanisms.

A cell culture model system, if a close mimic of host environmental conditions, can serve as an inexpensive, reproducible and easily manipulatable ...

Application of Fluorescent Nanoparticles to Study Remodeling of the Endo-lysosomal System by Intracellular Bacteria

Fluorescent nanoparticles (NPs) with desirable chemical, optical and mechanical properties are promising tools to label intracellular organelles. Here, we introduce a method using gold-BSA-rhodamine NPs to label the endo-lysosomal system of eukaryotic cells and monitor manipulations of host cellular pathways by the intracellular pathogen Salmonella enterica. The NPs were readily internalized by HeLa cells and localized in late endosomes/lysosomes. Salmonella infection induced rearrangement of the vesicles and accumulation of NPs in Salmonella-induced membrane structures. We deployed the Imaris software package for quantitative analyses of confocal microscopy images. The number of objects and their size distribution in non-infected cells were distinct from the ones in Salmonella-infected cells, indicating extremely remodeling of the endo-lysosomal system by WT Salmonella.

This article describes methods for the synthesis and fluorescent labeling of nanoparticles (NPs). The NPs were applied in pulse-chase experiments to label the endo-lysosomal system of eukaryotic cells. Manipulation of the endo-lysosomal system by activities of the intracellular pathogen Salmonella enterica were followed by live cell imaging and quantified.

Fluorescent nanoparticles (NPs) with desirable chemical, optical and mechanical properties are promising tools to label intracellular organelles. Here, we ...

Applying an Inducible Expression System to Study Interference of Bacterial Virulence Factors with Intracellular Signaling

The technique presented here allows one to analyze at which step a target protein, or alternatively a small molecule, interacts with the components of a signaling pathway. The method is based, on the one hand, on the inducible expression of a specific protein to initiate a signaling event at a defined and predetermined step in the selected signaling cascade. Concomitant expression, on the other hand, of the gene of interest then allows the investigator to evaluate if the activity of the expressed target protein is located upstream or downstream of the initiated signaling event, depending on the readout of the signaling pathway that is obtained. Here, the apoptotic cascade was selected as a defined signaling pathway to demonstrate protocol functionality. Pathogenic bacteria, such as Coxiella burnetii, translocate effector proteins that interfere with host cell death induction in the host cell to ensure bacterial survival in the cell and to promote their dissemination in the organism. The C. burnetii effector protein CaeB effectively inhibits host cell death after induction of apoptosis with UV-light or with staurosporine. To narrow down at which step CaeB interferes with the propagation of the apoptotic signal, selected proteins with well-characterized pro-apoptotic activity were expressed transiently in a doxycycline-inducible manner. If CaeB acts upstream of these proteins, apoptosis will proceed unhindered. If CaeB acts downstream, cell death will be inhibited. The test proteins selected were Bax, which acts at the level of the mitochondria, and caspase 3, which is the major executioner protease. CaeB interferes with cell death induced by Bax expression, but not by caspase 3 expression. CaeB, thus, interacts with the apoptotic cascade between these two proteins.

The method described here is used to induce the apoptotic signaling cascade at defined steps in order to dissect the activity of an anti-apoptotic bacterial effector protein. This method can also be used for inducible expression of pro-apoptotic or toxic proteins, or for dissecting interference with other signaling pathways.

The technique presented here allows one to analyze at which step a target protein, or alternatively a small molecule, interacts with the components of a ...

Visualization of HIV-1 Gag Binding to Giant Unilamellar Vesicle (GUV) Membranes

The structural protein of HIV-1, Pr55Gag (or Gag), binds to the plasma membrane in cells during the virus assembly process. Membrane binding of Gag is an essential step for virus particle formation, since a defect in Gag membrane binding results in severe impairment of viral particle production. To gain mechanistic details of Gag-lipid membrane interactions, in vitro methods based on NMR, protein footprinting, surface plasmon resonance, liposome flotation centrifugation, or fluorescence lipid bead binding have been developed thus far. However, each of these in vitro methods has its limitations. To overcome some of these limitations and provide a complementary approach to the previously established methods, we developed an in vitro assay in which interactions between HIV-1 Gag and lipid membranes take place in a &#34;cell-like&#34; environment. In this assay, Gag binding to lipid membranes is visually analyzed using YFP-tagged Gag synthesized in a wheat germ-based in vitro translation system and GUVs prepared by an electroformation technique. Here we describe the background and the protocols to obtain myristoylated full-length Gag proteins and GUV membranes necessary for the assay and to detect Gag-GUV binding by microscopy.

Visualization of HIV-1 Gag Binding to Giant Unilamellar Vesicle GUV Membranes

We illustrate here an in vitro membrane binding assay in which interactions between HIV-1 Gag and lipid membranes are visually analyzed using YFP-tagged Gag synthesized in a wheat germ-based in vitro translation system and GUVs prepared by an electroformation technique.

The structural protein of HIV-1, Pr55Gag (or Gag), binds to the plasma membrane in cells during the virus assembly process. Membrane binding of Gag is an ...

Retroviral Transduction of Helper T Cells as a Genetic Approach to Study Mechanisms Controlling their Differentiation and Function

Helper T cell development and function must be tightly regulated to induce an appropriate immune response that eliminates specific pathogens yet prevents autoimmunity. Many approaches involving different model organisms have been utilized to understand the mechanisms controlling helper T cell development and function. However, studies using mouse models have proven to be highly informative due to the availability of genetic, cellular, and biochemical systems. One genetic approach in mice used by many labs involves retroviral transduction of primary helper T cells. This is a powerful approach due to its relative ease, making it accessible to almost any laboratory with basic skills in molecular biology and immunology. Therefore, multiple genes in wild type or mutant forms can readily be tested for function in helper T cells to understand their importance and mechanisms of action. We have optimized this approach and describe here the protocols for production of high titer retroviruses, isolation of primary murine helper T cells, and their transduction by retroviruses and differentiation toward the different helper subsets. Finally, the use of this approach is described in uncovering mechanisms utilized by microRNAs (miRNAs) to regulate pathways controlling helper T cell development and function.

Many experimental systems have been utilized to understand the mechanisms regulating T cell development and function in an immune response. Here a genetic approach using retroviral transduction is described, which is economic, time efficient, and most importantly, highly informative in identifying regulatory pathways.

Helper T cell development and function must be tightly regulated to induce an appropriate immune response that eliminates specific pathogens yet prevents ...

Intraperitoneal Glucose Tolerance Test, Measurement of Lung Function, and Fixation of the Lung to Study the Impact of Obesity and Impaired Metabolism on Pulmonary Outcomes

Obesity and respiratory disorders are major health problems. Obesity is becoming an emerging epidemic with an expected number of over 1 billion obese individuals worldwide by 2030, thus representing a growing socioeconomic burden. Simultaneously, obesity-related comorbidities, including diabetes as well as heart and chronic lung diseases, are continuously on the rise. Although obesity has been associated with increased risk for asthma exacerbations, worsening of respiratory symptoms, and poor control, the functional role of obesity and perturbed metabolism in the pathogenesis of chronic lung disease is often underestimated, and underlying molecular mechanisms remain elusive. This article aims to present methods to assess the effect of obesity on metabolism, as well as lung structure and function. Here, we describe three techniques for mice studies: (1) assessment of intraperitoneal glucose tolerance (ipGTT) to analyze the effect of obesity on glucose metabolism; (2) measurement of airway resistance (Res) and respiratory system compliance (Cdyn) to analyze the effect of obesity on lung function; and (3) preparation and fixation of the lung for subsequent quantitative histological assessment. Obesity-related lung diseases are probably multifactorial, stemming from systemic inflammatory and metabolic dysregulation that potentially adversely influence lung function and the response to therapy. Therefore, a standardized methodology to study molecular mechanisms and the effect of novel treatments is essential.

The incidence of obesity is rising and increases the risk of chronic lung diseases. To establish the underlying mechanisms and preventive strategies, well-defined animal models are needed. Here, we provide three methods (glucose-tolerance-test, body plethysmography, and lung fixation) to study the effect of obesity on pulmonary outcomes in mice.

Obesity and respiratory disorders are major health problems. Obesity is becoming an emerging epidemic with an expected number of over 1 billion obese ...

Evaluation of Extracellular Vesicle Function During Malaria Infection

Malaria is a life-threatening disease caused by Plasmodium parasites, with P. falciparum being the most prevalent on the African continent and responsible for most malaria-related deaths globally. Several factors including parasite sequestration in tissues, vascular dysfunction, and inflammatory responses influence the evolution of the disease in malaria-infected people. P. falciparum-infected red blood cells (iRBCs) release small extracellular vesicles (EVs) containing different kinds of cargo molecules that mediate pathogenesis and cellular communication between parasites and host. EVs are efficiently taken up by cells in which they modulate their function. Here we discuss strategies to address the role of EVs in parasite-host interactions. First, we describe a straightforward method for labeling and tracking EV internalization by endothelial cells, using a green cell linker dye. Second, we report a simple way to measure permeability across an endothelial cell monolayer by using a fluorescently labeled dextran. Finally, we show how to investigate the role of small non-coding RNA molecules in endothelial cell function.

In this work, we describe protocols to investigate the role of extracellular vesicles (EVs) released by Plasmodium falciparum infected erythrocytes. In particular, we focus on the interactions of EVs with endothelial cells.

Malaria is a life-threatening disease caused by Plasmodium parasites, with P. falciparum being the most prevalent on the African continent and responsible ...

Purification of High Yield Extracellular Vesicle Preparations Away from Virus

One of the major hurdles in the field of extracellular vesicle (EV) research today is the ability to achieve purified EV preparations in a viral infection setting. The presented method is meant to isolate EVs away from virions (i.e., HIV-1), allowing for a higher efficiency and yield compared to conventional ultracentrifugation methods. Our protocol contains three steps: EV precipitation, density gradient separation, and particle capture. Downstream assays (i.e., Western blot, and PCR) can be run directly following particle capture. This method is advantageous over other isolation methods (i.e., ultracentrifugation) as it allows for the use of minimal starting volumes. Furthermore, it is more user friendly than alternative EV isolation methods requiring multiple ultracentrifugation steps. However, the presented method is limited in its scope of functional EV assays as it is difficult to elute intact EVs from our particles. Furthermore, this method is tailored towards a strictly research-based setting and would not be commercially viable.

This protocol isolates extracellular vesicles (EVs) away from virions with high efficiency and yield by incorporating EV precipitation, density gradient ultracentrifugation, and particle capture to allow for a streamlined workflow and a reduction of starting volume requirements, resulting in reproducible preparations for use in all EV research.

One of the major hurdles in the field of extracellular vesicle (EV) research today is the ability to achieve purified EV preparations in a viral infection ...

Live-Cell Forward Genetic Approach to Identify and Isolate Developmental Mutants in Chlamydia trachomatis

The intracellular bacterial pathogen Chlamydia trachomatis undergoes a developmental cycle consisting of two morphologically discrete developmental forms. The non-replicative elementary body (EB) initiates infection of the host. Once inside, the EB differentiates into the reticulate body (RB). The RB then undergoes multiple rounds of replication, before differentiating back to the infectious EB form. This cycle is essential for chlamydial survival as failure to switch between cell types prevents either host invasion or replication.
Limitations in genetic techniques due to the obligate intracellular nature of Chlamydia have hampered identification of the molecular mechanisms involved in the cell-type development. We designed a novel dual promoter-reporter plasmid system that, in conjunction with live-cell microscopy, allows for the visualization of cell type switching in real time. To identify genes involved in the regulation of cell-type development, the live-cell promoter-reporter system was leveraged for the development of a forward genetic approach by combining chemical mutagenesis of the dual reporter strain, imaging and tracking of Chlamydia with altered developmental kinetics, followed by clonal isolation of mutants. This forward genetic workflow is a flexible tool that can be modified for directed interrogation into a wide range of genetic pathways.

Live-Cell Forward Genetic Approach to Identify and Isolate Developmental Mutants in Chlamydia trachomatis

This protocol utilizes fluorescent promoter-reporters, live-cell microscopy, and individual inclusion extraction in a directed forward genetic approach to identify and isolate developmental mutants of Chlamydia trachomatis.

The intracellular bacterial pathogen Chlamydia trachomatis undergoes a developmental cycle consisting of two morphologically discrete developmental forms. ...