Rho kinase / ROCK

Y-27632 (25) is a synthetic pyridine derivative that inhibits Rho kinase (ROCK)-I and ROCK-II. As expected, Y27632 (25) inhibits the formation of stress fibers in cultured cells and motility in a number of systems [36]. In addition, two isoquinoline sulfonamides, HA1077 (26) and H-1152 (27), were developed as ROCK inhibitors [37,38]. 

Rho kinase (ROCK) inhibitors are potential therapeutic agents for cardiovascular diseases ranging from hypertension to atherosclerosis. Our chemistry effort has been focused around the initial lead dihydropyrimidine 1, which suffered from poor oral bioavailability, moderate Rho kinase potency, and potent P450 inhibition. Lead optimization efforts resulted in the identification of 2 which represents an improvement in all three properties. The SAR and X-Ray cocrystal structure of an advanced compound will be described. 

Takahashi N, Saya H, Kaibuchi K. Localization of the gene coding for ROCK II/Rho kinase on human chromosome 2p24. Genomics 1999 55 235-237. 

Schroter, T. et al. 2008. Comparison of miniaturized time-resolved fluorescence resonance energy transfer and enzyme-coupled luciferase high-throughput screening assays to discover inhibitors of Rho-kinase II (ROCK-II). J. Biomol. Screen. 13, 17-28. 

K, Narumiya S (1999) Signahng from Rho to the actin cytoskeleton through protein kinases ROCK and LIM-kinase. Science 285 895-898... 

Ohashi K, Nagata K, Maekawa M, IshizaM T, Narumiya S, Mizuno K (2000) Rho-associated kinase ROCK activates LlM-kinase 1 by phosphorylation at threonine 508 within the activation loop. J Biol Chem 275 3577-3582... 

One major challenge in hESC culture is a low survival rate after cell dissociation. Genetic manipulation (e.g., gene-targeting), and to a lesser extent, routine culture and directed differentiation are all reliant on clonal survival and/or cell dissociation. In a small screen, a selective small-molecule inhibitor of pl60-rho-associated coiled-coil kinase (ROCK), Y-27632, was found to increase hESC survival. The mechanism of action by which Y-27632 inhibits apoptosis, which is yet to be identified, should yield insights as to the causes of poor survival after dissociation (24). 

GTP-Rho is known to activate several downstream kinases. One class of Rho-kinases, Rho-associated coiled-coil forming kinases (ROCKs), regulate formation of focal contacts and stress fibers in several cell types by affecting myosin light chain [263]. 

Maekawa, M., Ishizaki, T, Boku, S., Watanabe, N., Fujita, A., Iwamatsu, A., Obinata, T., Ohashi, K., Mizuno, K. and Narumiya, S. (1999). Signaling from Rho to the actin cytoskeleton through protein kinases ROCK and LIM-kinase. Science 285, 895-898. 

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