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| Research Interests |
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| The major research focus in Dr. Chacko’s laboratory are: Molecular/Cellular Mechanisms For Smooth Muscle Contractile Dysfunctions: Our experiments to study the mechanisms for contractile dysfunctions are directed to understand the regulation of actomyosin ATPase and contraction in normal and pathological smooth muscles. Specifically, the roles of smooth muscle myosin isoforms, myosin light chain phosphorylation, and thin filament-associated proteins (caldesmon and calponin) in actin-myosin interaction and cross-bridge cycling are investigated. Remodeling Of Urinary Bladder Smooth Muscle In Outlet Obstruction: Molecular mechanisms for the regulation of actin-myosin interaction and contraction in normal and hypertrophied smooth muscle. A rabbit model for outlet obstruction is used to elucidate the mechanisms for altered contractility of the detrusor smooth muscle in men with outlet-obstruction in benign prostatic hyperplasia. This study is part of the George O'Brien Urology Research Center supported by a Center Grant from the National Institute for Diabetes, Digestive and Kidney Diseases (NIDDK), National Institute of Health (NIH). Molecular Mechanisms For Erectile Function And Dysfunction In Men: Cell and molecular biology of the contractile function of smooth muscle cells in the corpus cavernosum penis from normal rabbits and men with erectile dysfunctions. The present research focuses on the signal transduction pathway that is responsible for the GTP-mediated relaxation of the smooth muscle in the penis. In addition, we investigate the role of free radicals on the contractility of corpus cavernosum smooth muscle in alloxan-induced diabetes in rabbits. Mechanisms For The Urinary Bladder Dysfunction In Diabetes: Molecular and biochemical mechanisms for the altered contractility of the detrusor smooth muscle in diabetes are studied using streptozotocin-induced and alloxan-induced diabetes in rats and rabbits, respectively. The investigation includes the expression of isoforms of proteins (PK-C, MLCK, Rho-kinase, myosin, etc) involved contractile proteins and proteins involved in signal transduction. Cytodifferentiation Of Smooth Muscle: Differentiation of smooth muscle phenotypes during development. Transcriptional regulation of myosin isoforms in developing and pathological smooth muscle in the bladder wall is investigated. Technical Approaches include expression of contractile proteins using a bacculovirus expression system, site directed mutagenesis, gene knockouts, in situ hybridization, immunohistochemistry, in vitro motility assay & enzymatic assays to study the actin-myosin interaction, and studies using fluorescent labeled proteins to study protein conformation during protein-protein interaction. SOME OF OUR RECENT PAPERS ARE GIVEN BELOW: Zheng, Y., Weber, W.T., Wang, S., Wein, A.J., Chacko, S., and DiSanto , M.E. (2002) Establishment of a phenotypically stable bladder myocyte cell line from hypertrophied detrusor smooth muscle. Am. J. Physiol Cell Physiology 283:C373-382 Chang, S., Hypolite, J., Changolkar, A., Wein, AJ., Chacko, S. DiSanto, ME (2003) Increased contractility of diabetic rabbit copora smooth muscle in response to endothelin is mediated via Rho-kinase β. Int J Impot Res 15: 53-62 DiSanto ME, Stein R, Chang S, Hypolite JA, Zheng Y, Zderic S, Wein AJ, Chacko S. (2003) Alteration in the expression of myosin isoforms in detrusor smooth muscle following bladder outlet obstruction.Am J Physiol Cell Physiol., 285(6):C1397-410. Bing W, Chang S, Hypolite JA, DiSanto ME, Zderic SA, Rolf L, Wein AJ, Chacko S. (2003) Obstruction-induced changes in urinary bladder smooth muscle contractility: A role for Rho-kinase.Am J Physiol Renal Physiol., ;285(5):F990-7. Wu, His-Yang, Zderic, SA. Wein, AJ, and Chacko (2004) Decrease in maximal force generation in neonata mouse bladder corresponds to shift in myosin heavy chain isoform composition. J. Urol 171: 841-844. Shukla, RA., Nguyen T, Zheng, Y, Zderic, SA, DiSanto, ME, Wein, AJ, and Chacko, S (2004) Overexpression of smooth muscle specific caldesmon by transfection and intermittent agonist-induced contraction alters cellular morphology and restores differentiated smooth muscle phenotype. J. Urol 171:1949-1954 Zhang E, Stein R, Chang S, Zheng Y, Zderic SA, Wein AJ, and Chacko S. (2004) Smooth Muscle Hypertrophy following Partial Bladder Outlet Obstruction is Associated with Overexpression of Non-Muscle Caldesmon. Am J. Pathology.,164: 601-612. Hutcheson JC;Stein R;Canning DA;Wein AJ;Chacko S;Zderic SA; (2004) Murine in vitro whole bladder physiology Adv Exp Med Biol 539(0): 337-345 |
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| Selected Publications |
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| Chacko, S. and Longhurst, P.A. (1995) Contractile proteins and their response to bladder outlet obstruction. Adv. Exp. Med. & Biol. 385: 55-63
Horiuchi, KY. and Chacko, S. (1995) Effect of unphosphorylated smooth muscle on caldesmon-mediated regulation of actin filament velocity. J. Musc. Res. & Cell Motil. 16:11-19. Wang, Z, Gopalakurup, SK., Levin, RM., and Chacko, S. (1995) Expression of smooth muscle myosin isoforms in urinary bladder smooth muscle during hypertrophy and regression. Lab. Invest. 73:244-251. Horiuchi, KY., Wang, Z., and Chacko, S. (1995) Inhibition of smooth muscle actomyosin ATPase by caldesmon is associated with caldesmon-induced conformational changes in tropomyosin bound to actin. Biochemistry.34: 16815. Chacko, S. and Longhurst, P.A. (1995) Contractile proteins and their response to bladder outlet obstruction. Adv. Exp. Med. & Biol.385: 55-63. Wang, Z., Horiuchi, KY., and Chacko, S. (1996) Characterization of the functional domains of the C-terminal region of caldesmon using full-length and mutant caldesmon molecules. J. Biol. Chem. 271:271:2234-2242. Lau, LC. and Chacko, S. (1996) Identification of two types of smooth muscle cells from urinary bladder. Tissue Cell 28 (3): 339-355. Borovikov, Yu., Khoroshev, M I., and Chacko, S. (1996) Comparison of effects of calponin and 38-kDa caldesmon fragment on formation of Astrong-binding@ state in ghost muscle fibers. Biochem. Biophys. Res. Commun. 223:240-244. Wang, Z. And Chacko, S. (1996) Mutagenesis analysis of functionally important domains within the C- terminal end of smooth muscle caldesmon. J. Biol. Chem. 27:25707-25714. Borovikov, Yu., S., Horiuchi, K.Y., Avrova, S.V., and Chacko, S. (1966) Modulation of actin conformation and inhibition of actin filament velocity by calponin. Biochemistry. 35: 13849-13857. DiSanto, ME., Cox, RH., Wang, Z., and Chacko, S. (1997) Increased expression of myosin II with insertion in the NH2-terminal region of the distributing (muscular) arteries. Amer. J. Physiol. 272(Cell Physiol. 41): C1532-C1542. Wang, Z., Yang, Z-Q. , and Chacko, S. (1997) Functional and structural relationship between the calmodulin-binding, actin-binding, and actomyosin-ATPase inhibitory domains on the C terminus of smooth muscle caldesmon. J. Biol. Chem.272: 16896-16903. Chacko, S., DiSanto, M., Wang, Z, Zderic, SA. , and Wein, AJ. (1997). Contractile protein changes in urinary bladder smooth muscle during obstruction-induced hypertrophy. Scand. J.Urol. Neprol. 184: 67-76. Wang, Z., He, J., Yang, Z-Q. , and Chacko, S. (1997) Both N-terminal myosin binding and C-terminal actin-binding sites on smooth muscle caldesmon are required for caldesmon-mediated inhibition of actin filament velocity. Proc. Natl. Acad. Sci. 94: 11899-11904. Menon, C., and Chacko, S. (1998) Expression of caldesmon during differentiation of smooth muscle in developing chicken gizzard. Tissue & Cell, 30:118-126. DiSanto, M., Wang, Z, Menon, C., Zheng, M., Chacko, T., Hypolite, J., Broderick, G., Wein, AJ, and Chacko, S (1998) Expression of myosin isoforms in smooth muscle cells in the corpus cavernosum penis. Amer. J.Physiol.275: (Cell Physiol.44:): C976-C987. Chacko, S., DiSanto, M., Menon, M., Zheng, Y., Hypolite, J., and Wein, AJ. (1999) Contractile protein changes in the urinary bladder smooth muscle following outlet obstruction. In Advances in Bladder Research, eds. Baskin and Hayward, Plenium Publishers, New York. |
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Laboratory Members:
James O Marx, D.V. M., Ph.D.- Postdoctoral fellow |
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