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Phospholipase C and myosin light chain kinase inhibition define a common step in actin regulation during cytokinesis.
BMC Cell Biol 2007; 8:15BC

Abstract

BACKGROUND

Phosphatidylinositol 4,5-bisphosphate (PIP2) is required for successful completion of cytokinesis. In addition, both PIP2 and phosphoinositide-specific phospholipase C (PLC) have been localized to the cleavage furrow of dividing mammalian cells. PLC hydrolyzes PIP2 to yield diacylglycerol (DAG) and inositol trisphosphate (IP3), which in turn induces calcium (Ca2+) release from the ER. Several studies suggest PIP2 must be hydrolyzed continuously for continued cleavage furrow ingression. The majority of these studies employ the N-substituted maleimide U73122 as an inhibitor of PLC. However, the specificity of U73122 is unclear, as its active group closely resembles the non-specific alkylating agent N-ethylmaleimide (NEM). In addition, the pathway by which PIP2 regulates cytokinesis remains to be elucidated.

RESULTS

Here we compared the effects of U73122 and the structurally unrelated PLC inhibitor ET-18-OCH3 (edelfosine) on cytokinesis in crane-fly and Drosophila spermatocytes. Our data show that the effects of U73122 are indeed via PLC because U73122 and ET-18-OCH3 produced similar effects on cell morphology and actin cytoskeleton organization that were distinct from those caused by NEM. Furthermore, treatment with the myosin light chain kinase (MLCK) inhibitor ML-7 caused cleavage furrow regression and loss of both F-actin and phosphorylated myosin regulatory light chain from the contractile ring in a manner similar to treatment with U73122 and ET-18-OCH3.

CONCLUSION

We have used multiple inhibitors to examine the roles of PLC and MLCK, a predicted downstream target of PLC regulation, in cytokinesis. Our results are consistent with a model in which PIP2 hydrolysis acts via Ca2+ to activate myosin via MLCK and thereby control actin dynamics during constriction of the contractile ring.

Authors+Show Affiliations

Program in Developmental and Stem Cell Biology, The Hospital for Sick Children, TMDT Building, East Tower, Toronto, Ontario, Canada. re.wong@utoronto.ca <re.wong@utoronto.ca>No affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

17509155

Citation

Wong, Raymond, et al. "Phospholipase C and Myosin Light Chain Kinase Inhibition Define a Common Step in Actin Regulation During Cytokinesis." BMC Cell Biology, vol. 8, 2007, p. 15.
Wong R, Fabian L, Forer A, et al. Phospholipase C and myosin light chain kinase inhibition define a common step in actin regulation during cytokinesis. BMC Cell Biol. 2007;8:15.
Wong, R., Fabian, L., Forer, A., & Brill, J. A. (2007). Phospholipase C and myosin light chain kinase inhibition define a common step in actin regulation during cytokinesis. BMC Cell Biology, 8, p. 15.
Wong R, et al. Phospholipase C and Myosin Light Chain Kinase Inhibition Define a Common Step in Actin Regulation During Cytokinesis. BMC Cell Biol. 2007 May 17;8:15. PubMed PMID: 17509155.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Phospholipase C and myosin light chain kinase inhibition define a common step in actin regulation during cytokinesis. AU - Wong,Raymond, AU - Fabian,Lacramioara, AU - Forer,Arthur, AU - Brill,Julie A, Y1 - 2007/05/17/ PY - 2007/02/06/received PY - 2007/05/17/accepted PY - 2007/5/19/pubmed PY - 2007/6/27/medline PY - 2007/5/19/entrez SP - 15 EP - 15 JF - BMC cell biology JO - BMC Cell Biol. VL - 8 N2 - BACKGROUND: Phosphatidylinositol 4,5-bisphosphate (PIP2) is required for successful completion of cytokinesis. In addition, both PIP2 and phosphoinositide-specific phospholipase C (PLC) have been localized to the cleavage furrow of dividing mammalian cells. PLC hydrolyzes PIP2 to yield diacylglycerol (DAG) and inositol trisphosphate (IP3), which in turn induces calcium (Ca2+) release from the ER. Several studies suggest PIP2 must be hydrolyzed continuously for continued cleavage furrow ingression. The majority of these studies employ the N-substituted maleimide U73122 as an inhibitor of PLC. However, the specificity of U73122 is unclear, as its active group closely resembles the non-specific alkylating agent N-ethylmaleimide (NEM). In addition, the pathway by which PIP2 regulates cytokinesis remains to be elucidated. RESULTS: Here we compared the effects of U73122 and the structurally unrelated PLC inhibitor ET-18-OCH3 (edelfosine) on cytokinesis in crane-fly and Drosophila spermatocytes. Our data show that the effects of U73122 are indeed via PLC because U73122 and ET-18-OCH3 produced similar effects on cell morphology and actin cytoskeleton organization that were distinct from those caused by NEM. Furthermore, treatment with the myosin light chain kinase (MLCK) inhibitor ML-7 caused cleavage furrow regression and loss of both F-actin and phosphorylated myosin regulatory light chain from the contractile ring in a manner similar to treatment with U73122 and ET-18-OCH3. CONCLUSION: We have used multiple inhibitors to examine the roles of PLC and MLCK, a predicted downstream target of PLC regulation, in cytokinesis. Our results are consistent with a model in which PIP2 hydrolysis acts via Ca2+ to activate myosin via MLCK and thereby control actin dynamics during constriction of the contractile ring. SN - 1471-2121 UR - https://www.unboundmedicine.com/medline/citation/17509155/Phospholipase_C_and_myosin_light_chain_kinase_inhibition_define_a_common_step_in_actin_regulation_during_cytokinesis_ L2 - https://bmccellbiol.biomedcentral.com/articles/10.1186/1471-2121-8-15 DB - PRIME DP - Unbound Medicine ER -