David Shechter, Ph.D.
Chromatin and the Biochemistry of Epigenetic Information
Our research interests are focused on understanding chromatin, the complex of DNA, histones, and other proteins that constitute the physiological form of the genome. In particular, we are interested in the role of histone post-translational modifications and histone chaperones in establishing an embryonic epigenetic state, how this process is misregulated in cancers, and how to drug components of the machinery.
Epigenetics is a phenomenon important for an overall increase in the complexity of the genome without changes in gene sequence. Post-translational modifications of histones, and deposition of histone variants, establish a “histone code” of activation or repression of transcription and other chromatin-mediated transactions, and constitute a major part of the epigenome. Epigenetic information is information content "on top of" the DNA-encoded genetic material. Epigenetic information is the landscape on which the dynamic usage of genetic information is encoded.
We primarily utilize protein biochemistry and enzymology, structural biology, and embryos of the frog Xenopus laevis in our studies. These tools allow us to probe evolutionarily conserved mechanisms specifying critical events in chromatin biology and in maternal and zygotic control of development. Our combined use of rigorous in vitro studies along with in vivo studies in the frog provides an uncompromised approach to fully understanding epigenetic phenomena.We are currently pursuing a number of specific research avenues, including:
- determination of the biochemical mechanisms and biological function of the essential PRMT5-MEP50 histone arginine methyltransferase complex
- applying cutting-edge rational approaches to design small molecule chemical probes and lead molecules for drug screening for PRMT5
- analyzing the histone code specified by PRMT5-catalyzed histone methylation in embryos and breast cancer cells
- Determining how phosphorylation, methylation, and glutamylation of histone chaperones Nucleoplasmin and Nap1 occur and how these post-translational modifications regulate histone deposition activity
- Using quantitative techniques (hydrogen-deuterium exchange, NMR, biosensors) to understand histone chaperone binding and release of histones
These studies are designed to probe the molecular role of chromatin components in the establishment of the embryonic state and have direct bearings on understanding basic events in development and cancer. Our approach provides a unique “bottom-up” molecular understanding of the role of egg components, such as pre-deposition histones, histone modifications, and histone chaperones, in writing the embryonic chromatin state.
- Structure of the Arginine Methyltransferase PRMT5-MEP50 Reveals a Mechanism for Substrate SpecificityHo MC, Wilczek C, Bonanno JB, Xing L, Seznec J, Matsui T, Carter LG, Onikubo T, Kumar PR, Chan MK, Brenowitz M, Cheng RH, Reimer U, Almo SC, Shechter D.(2013).PLoS ONE 8(2): e57008. doi:10.1371/journal.pone.0057008.
- Protein Arginine Methyltransferase Prmt5-Mep50 Methylates Histones H2A and H4 and the Histone Chaperone Nucleoplasmin in Xenopus laevis Eggs. Wilczek C, Chitta R, Woo E, Shabanowitz J, Chait BT, Hunt DF, Shechter D.. J Biol Chem.2011 Dec 9;286(49):42221-31. Epub 2011 Oct 18.
- A distinct H2A.X isoform is enriched in Xenopus laevis eggs and early embryos and is phosphorylated in the absence of a checkpoint. Shechter D, Chitta RK, Xiao A, Shabanowitz J, Hunt DF, Allis CD. Proc Natl Acad Sci U S A. 2009 Jan 20;106(3):749-54. Epub 2009 Jan 8.
- WSTF regulates the H2A.X DNA damage response via a novel tyrosine kinase activity. Xiao A, Li H, Shechter D, Ahn SH, Fabrizio LA, Erdjument-Bromage H, Ishibe-Murakami S, Wang B, Tempst P, Hofmann K, Patel DJ, Elledge SJ, Allis CD. Nature. 2009 Jan 1;457(7225):57-62. Epub 2008 Dec 17.
- Analysis of histones in Xenopus laevis. I. A distinct index of enriched variants and modifications exists in each cell type and is remodeled during developmental transitions. Shechter D, Nicklay JJ, Chitta RK, Shabanowitz J, Hunt DF, Allis CD. J Biol Chem. 2009 Jan 9;284(2):1064-74. Epub 2008 Oct 28.
- Analysis of histones in Xenopus laevis. II. mass spectrometry reveals an index of cell type-specific modifications on H3 and H4. Nicklay JJ, Shechter D, Chitta RK, Garcia BA, Shabanowitz J, Allis CD, Hunt DF. J Biol Chem. 2009 Jan 9;284(2):1075-85. Epub 2008 Oct 28.
- Extraction, purification and analysis of histones. Shechter D, Dormann HL, Allis CD, Hake SB. Nat Protoc. 2007;2(6):1445-57.
- ATM and ATR check in on origins: a dynamic model for origin selection and activation. Shechter D, Gautier J. Cell Cycle. 2005 Feb;4(2):235-8. Epub 2005 Feb 13.
- DNA unwinding is an Mcm complex-dependent and ATP hydrolysis-dependent process. Shechter D, Ying CY, Gautier J. J Biol Chem. 2004 Oct 29;279(44):45586-93. Epub 2004 Aug 23.
- Regulation of DNA replication by ATR: signaling in response to DNA intermediates. Shechter D, Costanzo V, Gautier J. DNA Repair (Amst). 2004 Aug-Sep;3(8-9):901-8. Review.
- MCM proteins and checkpoint kinases get together at the fork. Shechter D, Gautier J. Proc Natl Acad Sci U S A. 2004 Jul 27;101(30):10845-6. Epub 2004 Jul 19.
- ATR and ATM regulate the timing of DNA replication origin firing. Shechter D, Costanzo V, Gautier J. Nat Cell Biol. 2004 Jul;6(7):648-55. Epub 2004 Jun 27.
- An ATR- and Cdc7-dependent DNA damage checkpoint that inhibits initiation of DNA replication. Costanzo V, Shechter D, Lupardus PJ, Cimprich KA, Gottesman M, Gautier J. Mol Cell. 2003 Jan;11(1):203-13.
- The intrinsic DNA helicase activity of Methanobacterium thermoautotrophicum delta H minichromosome maintenance protein. Shechter DF, Ying CY, Gautier J. J Biol Chem. 2000 May 19;275(20):15049-59.
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More Information About Dr. David Shechter
Shechter Lab Website - Research Interests, Lab Members, Protocols, Photos, etc
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