This work was supported by NIH grant NS042197 to MD. AJK was supported by grants T32GM008719 and F30NS068006.

1. Production of Microinjection Needles
<ol>
 <li>Pre-fabricated microinjection needles are available commercially (e.g. Femtotips from Eppendorf) and are useful if one is not performing a large number of microinjections. However, for those who wish to establish long-term capabilities for microinjecting, an alternative is to produce microinjection needles in the lab using thin wall borosilicate glass capillaries and a commercial needle puller. This also allows the shape of needles to be varied, which can be u...

<ol>
	<li>Danial, N. N., Korsmeyer, S. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cell+death:+critical+control+points.">Cell death: critical control points.</a> Cell. 116, 205-219 (2004).</li><li>Wang, X. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+expanding+role+of+mitochondria+in+apoptosis.">The expanding role of mitochondria in apoptosis.</a> Genes Dev. 15, 2922-2933 (2001).</li><li>Hengartner, M. O. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+biochemistry+of+apoptosis.">The biochemistry of apoptosis.</a> Nature. 407, 770-776 (2000).</li><li>Fuentes-Prior, P., Salvesen, G. 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+protein+structures+that+shape+caspase+activity,+specificity,+activation+and+inhibition.">The protein structures that shape caspase activity, specificity, activation and inhibition.</a> Biochem. J. 384, 201-232 (2004).</li><li>Tait, S. W., Green, D. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Mitochondria+and+cell+death:+outer+membrane+permeabilization+and+beyond.">Mitochondria and cell death: outer membrane permeabilization and beyond.</a> Nat Rev Mol Cell Biol. 11, 621-632 (2010).</li><li>Brustugun, O. T., Fladmark, K. E., Doskeland, S. O., Orrenius, S., Zhivotovsky, B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Apoptosis+induced+by+microinjection+of+cytochrome+c+is+caspase-dependent+and+is+inhibited+by+Bcl-2.">Apoptosis induced by microinjection of cytochrome c is caspase-dependent and is inhibited by Bcl-2.</a> Cell Death Differ. 5, 660-668 (1998).</li><li>Li, F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cell-specific+induction+of+apoptosis+by+microinjection+of+cytochrome+c.+Bcl-XL+has+activity+independent+of+cytochrome+c+release.">Cell-specific induction of apoptosis by microinjection of cytochrome c. Bcl-XL has activity independent of cytochrome c release.</a> J. Biol. Chem. 272, 30299-30305 (1997).</li><li>Deshmukh, M., Johnson, E. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Evidence+of+a+novel+event+during+neuronal+death:+development+of+competence-to-die+in+response+to+cytoplasmic+cytochrome+c.">Evidence of a novel event during neuronal death: development of competence-to-die in response to cytoplasmic cytochrome c.</a> Neuron. 21, 695-705 (1998).</li><li>Vaughn, A. E., Deshmukh, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Glucose+metabolism+inhibits+apoptosis+in+neurons+and+cancer+cells+by+redox+inactivation+of+cytochrome+c.">Glucose metabolism inhibits apoptosis in neurons and cancer cells by redox inactivation of cytochrome c.</a> Nat. Cell Biol. 10, 1477-1483 (2008).</li><li>Yang, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Prevention+of+apoptosis+by+Bcl-2:+release+of+cytochrome+c+from+mitochondria+blocked.">Prevention of apoptosis by Bcl-2: release of cytochrome c from mitochondria blocked.</a> Science. 275, 1129-1132 (1997).</li><li>Gonzales, D. H., Neupert, W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Biogenesis+of+mitochondrial+c-type+cytochromes.">Biogenesis of mitochondrial c-type cytochromes.</a> J Bioenerg Biomembr. 22, 753-768 (1990).</li><li>Ellerby, H. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Establishment+of+a+cell-free+system+of+neuronal+apoptosis+-+comparison+of+premitochondrial,+mitochondrial,+and+postmitochondrial+phases.">Establishment of a cell-free system of neuronal apoptosis - comparison of premitochondrial, mitochondrial, and postmitochondrial phases.</a> J. Neurosci. 17, 6165-6178 (1997).</li><li>Neame, S. J., Rubin, L. L., Philpott, K. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Blocking+cytochrome+c+activity+within+intact+neurons+inhibits+apoptosis.">Blocking cytochrome c activity within intact neurons inhibits apoptosis.</a> J. Cell Biol. 142, 1583-1593 (1998).</li><li>Potts, P. R., Singh, S., Knezek, M., Thompson, C. B., Deshmukh, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Critical+function+of+endogenous+XIAP+in+regulating+caspase+activation+during+sympathetic+neuronal+apoptosis.">Critical function of endogenous XIAP in regulating caspase activation during sympathetic neuronal apoptosis.</a> J. Cell Biol. 163, 789-799 (2003).</li><li>Estus, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Altered+gene+expression+in+neurons+during+programmed+cell+death:+identification+of+c-jun+as+necessary+for+neuronal+apoptosis.">Altered gene expression in neurons during programmed cell death: identification of c-jun as necessary for neuronal apoptosis.</a> J. Cell Biol. 127, 1717-1727 (1994).</li></ol>

All experimental procedures on animals were approved by the Institutional Animal Care and Use Committee at the University of North Carolina.

The microinjection of cytochrome c directly into the cytoplasm of cells is a unique and powerful tool which allows for studies of the post-mitochondrial regulation of apoptosis. Importantly, this technique allows for the direct activation of apoptosis downstream of mitochondria without the use of agents which cause cellular or mitochondrial damage. 
While this protocol has focused on microinjection of cytochrome c for studies on apoptosis, the general principles of protein ...

<table border="1">
	<tbody>
 <tr>
 	<th>Name of the reagent</th>
 <th>Company</th>
 <th>Catalogue number</th>
 <th>Comments</th>
 </tr>
 <tr>
 	<td>DM IRE2 Inverted Microscope</td>
 <td>Leica</td>
 <td>&nbsp;</td>
 <td>&nbsp;</td>
 </tr>
 <tr>
 	<td>PC-10 Microinjection Needle Puller</td>
 <td>Narishige</td>
 <td>&nbsp;</td>
 <td>&nbsp;</td>
 </tr>
 <tr>
 	<td>MWO-202 Micromanipulator</td>
 <td>Narishige</td>
 <td>&nbsp;</td>
 <td>&nbsp;</td>
 </tr>
 <tr>
 	<td>FemtoJet Microinjector</td>
 <td>Eppendorf</td>
 <td>&nbsp;</td>
 <td>&nbsp;</td>
 </tr>
 <tr>
 	<td>Thin-wall Boroscilicate Capillary Glass with Microfilament</td>
 <td>A-M Systems</td>
 <td>615000</td>
 <td>4 inch length, 1.00 mm outer diameter, 0.75 mm inner diameter</td>
 </tr>
 <tr>
 	<td>Rhodamine B isothiocyanate-Dextran</td>
 <td>Sigma-Aldrich</td>
 <td>R9379</td>
 <td>Average molecular weight ~70,000 Da</td>
 </tr>
 <tr>
 	<td>Bovine Cytochrome c Protein</td>
 <td>Sigma-Aldrich</td>
 <td>C3131</td>
 <td>&nbsp;</td>
 </tr>
 
 </tbody>
</table>

activation of apoptosis by cytoplasmic microinjection of cytochrome c

Apoptosis, or programmed cell death, is a conserved and highly regulated pathway by which cells die1. Apoptosis can be triggered when cells encounter a wide range of cytotoxic stresses. These insults initiate signaling cascades that ultimately cause the release of cytochrome c from the mitochondrial intermembrane space to the cytoplasm2. The release of cytochrome c from mitochondria is a key event that triggers the rapid activation of caspases, the key cellular proteases which ultimately execute cell death3-4.
The pathway of apoptosis is regulated at points upstream and downstream of cytochrome c release from mitochondria5. In order to study the post-mitochondrial regulation of caspase activation, many investigators have turned to direct cytoplasmic microinjection of holocytochrome c (heme-attached) protein into cells6-9. Cytochrome c is normally localized to the mitochondria where attachment of a heme group is necessary to enable it to activate apoptosis10-11. Therefore, to directly activate caspases, it is necessary to inject the holocytochrome c protein instead of its cDNA, because while the expression of cytochrome c from cDNA constructs will result in mitochondrial targeting and heme attachment, it will be sequestered from cytosolic caspases. Thus, the direct cytosolic microinjection of purified heme-attached cytochrome c protein is a useful tool to mimic mitochondrial cytochrome c release and apoptosis without the use of toxic insults which cause cellular and mitochondrial damage.
In this article, we describe a method for the microinjection of cytochrome c protein into cells, using mouse embryonic fibroblasts (MEFs) and primary sympathetic neurons as examples. While this protocol focuses on the injection of cytochrome c for investigations of apoptosis, the techniques shown here can also be easily adapted for microinjection of other proteins of interest.

Watch this Scientific Journal Video about Activation of Apoptosis by Cytoplasmic Microinjection of Cytochrome c at JoVE.com

Activation of Apoptosis by Cytoplasmic Microinjection of Cytochrome c

In this protocol, we describe the direct cytoplasmic microinjection of cytochrome c protein into fibroblasts and primary sympathetic neurons. This technique allows for the introduction of cytochrome c protein into the cytoplasm of cells and mimics the release of cytochrome c from mitochondria, which occurs during apoptosis.

Activation of Apoptosis by Cytoplasmic Microinjection of Cytochrome c

Apoptosis, or programmed cell death, is a conserved and highly regulated pathway by which cells die1.  Apoptosis can be triggered when cells encounter a ...

activation-of-apoptosis-by-cytoplasmic-microinjection-of-cytochrome-c

Research

JoVE Journal

Biology

17.3K visualizações.  University of North Carolina. Neste protocolo, descrevemos a microinjeção direta citoplasmática de citocromo C Proteína em fibroblastos e primário neurônios simpáticos. Esta técnica permite a introdução do citocromo C Proteínas no citoplasma das células e imita a liberação de citocromo C A partir de mitocôndrias, que ocorre durante a apoptose.