Name: characterization at the molecular level using robust biochemical approaches of a new kinase protein
Uploaded: 2019-06-30T14:00:00
Description: Watch this Scientific Journal Video about Characterization at the Molecular Level using Robust Biochemical Approaches of a New Kinase Protein at JoVE.com

This work was supported by La Ligue contre le Cancer, l&#8217;Association Neurofibromatoses et Recklinghausen, and la R&#233;gion Centre Val de Loire. Many thanks to Aur&#233;lie Cosson and D&#233;borah Casas for flow cytometry data, and to Keyron Hickman-Lewis for thorough proofreading of the manuscript.

1. Cell preparation for transfection
CAUTION: All the steps of the cell culture must be performed in a dedicated laboratory, and cells are manipulated within a Class 2 microbiological cabinet.
<ol>
	<li>Seed HEK-293 (Human Embryonic Kidney) cells in &#216; 10 cm plates in 10 mL of DMEM (Dulbecco&#39;s Modified Eagles Medium) supplemented with 10% fetal calf serum. Culture for 3 to 5 days under 5% CO2, at 37 &#176;C, until the cells reach ~90% confluence.</li>
	<li>Treat &#216; 10 ...

<ol>
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Herein, we have used robust biochemical tools to characterize at the molecular level a new protein, LIMK2-1, believed to be a kinase based on its sequence and on its homologs, LIMK2a and LIMK2b20.
Firstly, we demonstrated the existence of LIMK2-1 at the protein level using Western Blot analysis with a specific antibody. Following this, we evaluated its interaction with the upstream kinase ROCK1, which is known to regulate LIMK2a and LIMK2b, the homologs of LIMK2-1. Fina...

For many decades, numerous signaling pathways have been elucidated and their involvement in crucial cellular processes such as cell division, differentiation, motility, programmed cell death, immunity and neurobiology, has been shown. Kinases play a significant role in these signaling pathways as they often finely regulate their activation or inactivation and are part of transient versatile complexes that respond to external stimuli1,2,3. Mutation and dysregulation of kinases often lead to diseases in humans, and they have therefore become one of the most important drug targets over the past forty years4.
In this context, it is important to be able to detect kinase interaction with their upstream regulators or downstream substrates and to identify new partners. Affinity purification and immunoprecipitation are very powerful techniques for the isolation of protein complexes5. The bait protein or kinase may be tagged with a specific peptide sequence allowing the use of commercial beads covalently coupled with antibodies targeting the peptide. This material permits a high reproducibility in experiments6,7,8. Endogenous proteins may also be immunoprecipitated using antibodies targeting directly the bait protein. The antibodies may be cross-linked to Protein A or Protein G agarose beads or simply incubated with these beads prior to adding lysate. Lysis buffers must be optimized to allow protein solubilization without losing interaction and to avoid protein degradation. A major drawback of this approach is that the interaction is detected upon cell lysis; therefore, transient or weak interactions, together with those requiring subcellular context may be missed. Other techniques may be used to work directly in the cell such as Proximity Ligation Assay (PLA)9, in vivo cross-linking-assisted affinity purification (XAP)10, Bioluminescence Resonance Energy Transfer (BRET) or F&#246;rster Resonance Energy Transfer (FRET)11,12. Furthermore, immunoprecipitation is not appropriate to determine the thermodynamic constants of the binding, for which physical techniques such as Surface Plasmon Resonance, Isothermal Titration Calorimetry or Microscale Thermophoresis are required13,14.
Kinase activity may be assessed using multiple techniques. Herein, we focused on phospho-specific antibodies and in vitro &#947;[32P] ATP (Adenosine TriPhosphate) labeling. Phospho-specific antibodies target the phosphate modification of a particular residue within a protein. They may be used in Western Blot or ELISA (Enzyme-Linked ImmunoSorbent Assay) after cell lysis, for immunohistochemistry, and also on intact cells using flow cytometry or immunofluorescence. Their drawbacks may include their lack of specificity, which can be evaluated using a mutated version of the target protein, and their not being commercially available for all proteins. In vitro &#947;[32P] ATP labeling is a very robust, well-established and highly sensitive method15. Immunoprecipitated or recombinant proteins may be used, and different substrates may be tested. The effects of drugs may also be assessed as this method is quantitative. Its major drawback is that the radioactivity associated with the approach requires handling with caution. Alternative methods are also possible based on the measurement of fluorescent or luminescent peptide substrates and taking advantage of altered fluorescent/luminescent properties upon phosphorylation. Such methods also allow high throughput, which is required, for example, in the screening of molecules that may be potential inhibitors of the target kinase. Indeed, kinases represent one of the largest classes of drug targets pursued by pharmaceutical companies16.
In this study, we focused on the LIMK2-1 protein (LIMK2-1 stands for Lin11, Isle1, Mec3 Kinase isoform 2-1). The LIMK2 kinase protein was first described in 199517. Three isoforms of LIMK2 are produced by alternative splicing: LIMK2a, LIMK2b and LIMK2-1. At present, LIMK2-1 has only been described at the mRNA level in a single study18. Herein, we characterize this potential new kinase protein at the molecular level using robust biochemical approaches. Firstly, we demonstrate that LIMK2-1 is indeed synthesized. Similar to its two counterparts, LIMK2a and LIMK2b, it interacts with the upstream kinase ROCK (Rho-associated protein kinase). We show LIMK2-1 has a kinase activity on Myelin Basic Protein (MBP), but not on cofilin, the canonical substrate of LIM kinases.

<table>
	<tbody>
		<tr>
			<td>Antibody anti-actin</td>
			<td>Sigma-Aldrich</td>
			<td>A1978</td>
			<td>for Western Blot</td>
		</tr>
		<tr>
			<td>Antibody anti-c-Myc</td>
			<td>Invitrogen</td>
			<td>MA1-21316</td>
			<td>for Western Blot</td>
		</tr>
		<tr>
			<td>Antibody anti-cofilin</td>
			<td>Cell signaling Technology</td>
			<td>3312/5175</td>
			<td>for Western Blot</td>
		</tr>
		<tr>
			<td>Antibody anti-GFP</td>
			<td>Santa Cruz</td>
			<td>sc-9996</td>
			<td>for Western Blot</td>
		</tr>
		<tr>
			<td>Antibody anti-HA</td>
			<td>Roche Applied Science</td>
			<td>11687423001</td>
			<td>for Western Blot</td>
		</tr>
		<tr>
			<td>Antibody anti-phospho-cofilin</td>
			<td>Cell signaling Technology</td>
			<td>3313</td>
			<td>for Western Blot</td>
		</tr>
		<tr>
			<td>Antibody Anti-PP1i</td>
			<td>Eurogentec</td>
			<td>designed for this study</td>
			<td>for Western Blot</td>
		</tr>
		<tr>
			<td>Aprotinin</td>
			<td>Euromedex</td>
			<td>A-162B</td>
			<td>for lysis buffer</td>
		</tr>
		<tr>
			<td>ATP</td>
			<td>Invitrogen</td>
			<td>PV3227</td>
			<td>for g[32P] labeling</td>
		</tr>
		<tr>
			<td>g[32P] ATP</td>
			<td>Perkin Elmer</td>
			<td>NEG502A</td>
			<td>for g[32P] labeling</td>
		</tr>
		<tr>
			<td>BES buffered saline</td>
			<td>Sigma-Aldrich</td>
			<td>14280</td>
			<td>for transfection</td>
		</tr>
		<tr>
			<td>b-glycerophosphate</td>
			<td>Sigma-Aldrich</td>
			<td>G9422</td>
			<td>for lysis and kinase buffer</td>
		</tr>
		<tr>
			<td>b-mercaptoethanol</td>
			<td>Sigma-Aldrich</td>
			<td>M3148</td>
			<td>for Laemmli</td>
		</tr>
		<tr>
			<td>BSA</td>
			<td>Sigma-Aldrich</td>
			<td>A3059</td>
			<td>for blocking buffer</td>
		</tr>
		<tr>
			<td>Bromophenol Blue</td>
			<td>Sigma-Aldrich</td>
			<td>B0126</td>
			<td>for Laemmli</td>
		</tr>
		<tr>
			<td>CaCl2</td>
			<td>Sigma-Aldrich</td>
			<td>C3881</td>
			<td>for transfection</td>
		</tr>
		<tr>
			<td>Centrifuge</td>
			<td>Sigma</td>
			<td>111-541</td>
			<td></td>
		</tr>
		<tr>
			<td>Collagen R</td>
			<td>Pan Biotech</td>
			<td>P06-20166</td>
			<td>for transfection</td>
		</tr>
		<tr>
			<td>Control siRNA</td>
			<td>Ambion</td>
			<td>AM4611</td>
			<td>for PP1i antibody specificity</td>
		</tr>
		<tr>
			<td>Coomassie PageBlue Protein Staining Solution</td>
			<td>Thermo-Fisher</td>
			<td>24620</td>
			<td>for gel staining</td>
		</tr>
		<tr>
			<td>EDTA</td>
			<td>Sigma-Aldrich</td>
			<td>3690</td>
			<td>for lysis buffer</td>
		</tr>
		<tr>
			<td>Electrophoresis Unit</td>
			<td>Biorad</td>
			<td>Mini-Protean</td>
			<td>for Western Blot</td>
		</tr>
		<tr>
			<td>EZview Red anti-HA affinity gel</td>
			<td>Sigma-Aldrich</td>
			<td>E6779</td>
			<td>for immunoprecipitation</td>
		</tr>
		<tr>
			<td>GeneSys software</td>
			<td>Ozyme</td>
			<td></td>
			<td>for Western Blot acquisition</td>
		</tr>
		<tr>
			<td>GeneTolls software</td>
			<td>Ozyme</td>
			<td></td>
			<td>for Western Blot quantification</td>
		</tr>
		<tr>
			<td>GFP-trap beads</td>
			<td>Chromtek</td>
			<td></td>
			<td>for immunoprecipitation</td>
		</tr>
		<tr>
			<td>Glycine</td>
			<td>Euromedex</td>
			<td>26-128-6405</td>
			<td>for transfer buffer</td>
		</tr>
		<tr>
			<td>GST-cofilin</td>
			<td>Upstate Cell signaling</td>
			<td>12-556</td>
			<td>for g[32P] labeling</td>
		</tr>
		<tr>
			<td>Hamilton syringe 100 mL</td>
			<td>Hamilton</td>
			<td>710</td>
			<td>to remove carefully supernatant from beads without aspirating them</td>
		</tr>
		<tr>
			<td>HEPES</td>
			<td>Sigma-Aldrich</td>
			<td>H3375</td>
			<td>for kinase buffer</td>
		</tr>
		<tr>
			<td>ImageQuant TL software</td>
			<td>GE Healthcare</td>
			<td></td>
			<td>for radioactivity acquisition and quantification</td>
		</tr>
		<tr>
			<td>LIMK2 siRNA</td>
			<td>Ambion</td>
			<td>s8191</td>
			<td>for PP1i antibody specificity</td>
		</tr>
		<tr>
			<td>Leupeptin</td>
			<td>Sigma-Aldrich</td>
			<td>SP-04-2217</td>
			<td>for lysis and kinase buffer</td>
		</tr>
		<tr>
			<td>MBP</td>
			<td>Upstate Cell signaling</td>
			<td>13-173</td>
			<td>for g[32P] labeling</td>
		</tr>
		<tr>
			<td>MgCl2</td>
			<td>Sigma-Aldrich</td>
			<td>M8266</td>
			<td>for kinase buffer</td>
		</tr>
		<tr>
			<td>MnCl2</td>
			<td>Sigma-Aldrich</td>
			<td>244589</td>
			<td>for kinase buffer</td>
		</tr>
		<tr>
			<td>NaCl</td>
			<td>Euromedex</td>
			<td>1112</td>
			<td>for lysis and kinase buffer</td>
		</tr>
		<tr>
			<td>NaF</td>
			<td>Sigma-Aldrich</td>
			<td>S-1504</td>
			<td>for lysis and kinase buffer</td>
		</tr>
		<tr>
			<td>Okaidic acid</td>
			<td>Euromedex</td>
			<td>0-2220</td>
			<td>for lysis buffer</td>
		</tr>
		<tr>
			<td>PMSF</td>
			<td>Sigma-Aldrich</td>
			<td>78830</td>
			<td>for lysis and kinase buffer</td>
		</tr>
		<tr>
			<td>p-nitrophenylphosphate</td>
			<td>Euromedex</td>
			<td>1026</td>
			<td>for lysis buffer</td>
		</tr>
		<tr>
			<td>PVDF membrane Immobillon-P</td>
			<td>Merck-Millipore</td>
			<td>IPVH00010 pore size 0,45 mm</td>
			<td>for Western Blot</td>
		</tr>
		<tr>
			<td>Rotating wheel</td>
			<td>Labinco</td>
			<td></td>
			<td>for bead incubation</td>
		</tr>
		<tr>
			<td>Safe lock eppendorf</td>
			<td>Eppendorf</td>
			<td>0030120.086</td>
			<td>for kinase assay</td>
		</tr>
		<tr>
			<td>SDS</td>
			<td>Sigma-Aldrich</td>
			<td>5030</td>
			<td>for Laemmli and migration buffer</td>
		</tr>
		<tr>
			<td>Sodium orthovanadate</td>
			<td>LC Laboratories</td>
			<td>S8507</td>
			<td>for lysis and kinase buffer</td>
		</tr>
		<tr>
			<td>Sodium pyrophosphate</td>
			<td>Fluka</td>
			<td>71501</td>
			<td>for lysis buffer</td>
		</tr>
		<tr>
			<td>Super Signal West Dura</td>
			<td>Protein Biology</td>
			<td>34075</td>
			<td>for Western Blot</td>
		</tr>
		<tr>
			<td>Syngene Pxi</td>
			<td>Ozyme</td>
			<td></td>
			<td>for Western Blot</td>
		</tr>
		<tr>
			<td>Tissue extracts 
			 
			&#160;</td>
			<td>Biochain 
			 
			&#160;</td>
			<td>P1234035 Brain 
			P12345152 Lung 
			P1234149 Liver 
			P1234188 Pancreas 
			P1234260 Testis</td>
			<td>for Western Blot analysis 
			 
			&#160;</td>
		</tr>
		<tr>
			<td>Transfer Unit</td>
			<td>Biorad</td>
			<td>Mini-Trans-Blot</td>
			<td>for Western Blot</td>
		</tr>
		<tr>
			<td>Tris</td>
			<td>Euromedex</td>
			<td>26-128-3094 B</td>
			<td>for lysis buffer</td>
		</tr>
		<tr>
			<td>Tween-20</td>
			<td>Sigma-Aldrich</td>
			<td>P7949</td>
			<td>for blocking buffer</td>
		</tr>
		<tr>
			<td>Typhoon FLA9500</td>
			<td>GE Healthcare</td>
			<td></td>
			<td>to read autoradiography</td>
		</tr>
		<tr>
			<td>Typhoon Trio</td>
			<td>Amersham Bioscience</td>
			<td></td>
			<td>to read autoradiography</td>
		</tr>
		<tr>
			<td>Whatman paper</td>
			<td>GE Healthcare</td>
			<td>3030-672</td>
			<td>for Western Blot</td>
		</tr>
	</tbody>
</table>

characterization at the molecular level using robust biochemical approaches of a new kinase protein

Extensive whole genome sequencing has identified many Open Reading Frames (ORFs) providing many potential proteins. These proteins may have important roles for the cell and may unravel new cellular processes. Among proteins, kinases are major actors as they belong to cell signaling pathways and have the ability to switch on or off many processes crucial to the fate of the cell, such as cell growth, division, differentiation, motility, and death.
In this study, we focused on a new potential kinase protein, LIMK2-1. We demonstrated its existence by Western Blot using a specific antibody. We evaluated its interaction with an upstream regulating protein using coimmunoprecipitation experiments. Coimmunoprecipitation is a very powerful technique able to detect the interaction between two target proteins. It may also be used to detect new partners of a bait protein. The bait protein may be purified either via a tag engineered to its sequence or via an antibody specifically targeting it. These protein complexes may then be separated by SDS-PAGE (Sodium Dodecyl Sulfate PolyAcrylamide Gel) and identified using mass spectrometry. Immunoprecipitated LIMK2-1 was also used to test its kinase activity in vitro by &#947;[32P] ATP labeling. This well-established assay may use many different substrates, and mutated versions of the bait may be used to assess the role of specific residues. The effects of pharmacological agents may also be evaluated since this technique is both highly sensitive and quantitative. Nonetheless, radioactivity handling requires particular caution. Kinase activity may also be assessed with specific antibodies targeting the phospho group of the modified amino acid. These kinds of antibodies are not commercially available for all the phospho modified residues.

LIMK2-1 protein is synthesized 
LIMK2-1 is mentioned in databanks, but thus far only one paper has shown the existence of its mRNA18. Compared to its two homologs, LIMK2a and LIMK2b, LIMK2-1 has an extra C-terminal domain identified as a Protein Phosphatase 1 Inhibitory domain (PP1i). We designed an antibody that targets a peptide of this domain, amino acids 671-684 (Figure 1A). 
BLAST research against human ...

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Characterization at the Molecular Level using Robust Biochemical Approaches of a New Kinase Protein

We characterized a new kinase protein using robust biochemical approaches: Western Blot analysis with a dedicated specific antibody on different cell lines and tissues, interactions by coimmunoprecipitation experiments, kinase activity detected by Western Blot using a phospho-specific antibody and by &#947;[32P] ATP labeling.

Extensive whole genome sequencing has identified many Open Reading Frames (ORFs) providing many potential proteins. These proteins may have important ...

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Biochemistry

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