Biology and Biochemistry Department
Office: SERC - 4004
Dr. Schwartz is recognized for defining the regulatory paradigm in which nonmuscle contractile proteins are switched off during muscle differentiation and replaced by muscle specific contractile protein isoforms; thus launching the field of myogenesis in 1981. In the late 1980's Dr. Schwartz identified a highly conserved repeated element shared by the 3 alpha actin genes, later identified as the serum response factor binding site. Over the next 15 years, Schwartz provided the earliest evidence that SRF functioned as the master regulatory platform that directs myogenic gene expression programs through combinatorial interactions with other transcription factors and cofactors. In 1996, SRF was shown to associate with Nkx 2.5 the vertebrate tinman homologue that co-activated cardiac actin gene activity and then a few years later SRF was shown to partner with GATA4-6 factors. The combination of LIM-only proteins CRP1 and CRP2 with SRF and GATA factors were shown as potent cardiovascular differentiation cofactors.
Four years ago, Dr. Schwartz presented a gene switch mechanism that facilitated strong repression of SRF-dependent myogenic differentiation genes through phosphorylation of a specific evolutionarily conserved SRF residue in the MADS box, that allowed for activation of immediate early proliferation genes. In addition, Dr. Schwartz and colleagues identified more than 180 direct SRF gene targets that have roles in cellular contractility, movement and mesoderm formation and the newly discovered SM-HAT, a key histone acetyl-transferase that associates with SRF, CRP2 and myocardin directing de novo smooth muscle gene activity.
Conditional knockouts of SRF with Dr. Schwartz' early expressing Nkx2-5Cre completely blocked the appearance of smooth muscle and cardiac actin gene activity and sarcomere formation in the heart; thus, bringing full circle, after 25 years, the absolute proof for SRF obligatory role in muscle differentiation and the gene regulation of myogenic contractile proteins.
Finally, in human disease, Dr. Schwartz discovered caspase 3 cleavage of SRF generated a dominant-negative transcription factor responsible for driving depressed contractility in human heart failure and will serve as a new biomarker for human heart failure. SRF is also an important regulator of microRNA expression in the heart involved with silencing inappropriate genes and allowing for cardiomyocyte lineage specification. Schwartz continues to elucidate the chemical basis underlying the specification of cardiac muscle cell differentiation, which will provide opportunities for cell replacement therapy and heart regeneration in the future.
Robert J. Schwartz, Ph.D. is a Professor in the Department of Biology and Biochemistry and the Director of the Center for Molecular Medicine and Experimental Therapeutic. He previously was at Baylor College of Medicine in Houston, where he served as a tenured professor in the Departments of Cell Biology, Molecular and Cellular Biology, Medicine, and Molecular Physiology. He also was co-director of the Baylor College of Medicine Center for Cardiovascular Development. Schwartz also spent five years at the Institute of Biosciences and Technology where he was the Director of the Institute. During his more than thirty five years in Houston, Schwartz became widely recognized for his research on the developmental and genetic aspects of congenital heart disease. In this field he has received eleven US patents and co-founded three companies. He earned his B.S. from Brooklyn College and his Ph.D. in Biology from the University of Pennsylvania.
Niu, Z, Iyer, D, Conway, SJ, Martin, JF, Ivey, K, Srivastava, D, Nordheim, A, and Schwartz, RJ (2008) Serum Response Factor orchestrates nascent sarcomerogenesis and silences biomineralization in the heart. Proc. Natl Acad Sci USA 105, 17824-17829.
Niu, Z., Li, A., Zhang, S.X., and Schwartz, R.J. (2007) Serum response factor micromanaging cardiogenesis. Curr Opin Cell Biol. 6:618-627.
Zhao, Y., Ransom, J.F., Li A., Vedantham, V., von Drehle, M., Muth, A.N., Tsuchihashi, T., McManus, M.T., Schwartz, R.J. and Srivastava, D. (2007) Dysregulation of Cardiogenesis, Cardiac Conduction, and Cell Cycle in Mice Lacking miRNA-1-2. Cell. 129, 303-317.
Chang,D.F, Belaguli,NS,, Roberts,WB., Iyer,D., Wu, S.P., Dong, X.R.,Marx,J., Moore, MS., Beckerle, M.C., Majesky, M., and. Schwartz, RJ. (2003) Vascular smooth muscle LIM-only proteins CRP1 and CRP2 are potent cardiovascular differentiation cofactors. Dev. Cell 4: 107-118.
Schwartz, R.J. and Olson, E.N. (1999) Building the heart piece by piece: modularity of cis-elements regulating to Nkx2-5 transcription. Development, 126, 4187-4192.
Chen, C.Y. and Schwartz, R.J. (1996) Recruitment of tinman homologue, Nkx-2.5 by serum response factor activates cardiac -actin gene transcription. Mol. Cell. Biol.,16:6372-6384.
Chen, C-Y. and Schwartz, R.J. (1995) Identification of novel DNA binding targets and regulatory domains of a murine tinman homeodomain factor, nkx-2.5. J. Biol. Chem. 270:15628-15633.
Schwartz, R.J. and Rothblum, K.N. (1981) Gene switching in myogenesis: differential expression of the chicken actin multigene family. Biochemistry 20:4122-4129.