Posts classified under: Institute Core Members

Penn Epigenetics > Faculty > Institute Core Members

Ronen Marmorstein, Ph.D.

Contribution to Science

1. My laboratory has pioneered the structure-function analysis of histone acetyltransferases (HATs) and continues to make seminal contributions in this area. Specifically, my laboratory determined the first crystal structure of a type A HAT and characterized its mechanism of catalysis, and the first to describe the mode of histone substrate binding by a HAT. My laboratory has extended our studies to the broader family of N- acetyltransferases including the non-histone lysine acetyltransferases (KATs) and the N-amino acetyltransferases (NATs). We have uncovered important molecular signatures that distinguish HATs, KATs and NATs. My laboratory has also contributed to the development of acetyltransferase inhibitors. The vast majority of the human proteome is acetylated in a functionally important manner and alterations occur in human diseases. This suggests that protein acetylation may rival protein phosphorylation as a biologically important protein modification and that KATs and NATs represent important therapeutic targets.
a. Deng, S., McTiernan, N., Wei, X., Arnesen, T. and Marmorstein, R. Molecular basis for N-terminal acetylation by human NatE and its modulation by HYPK, (2020) Nature Comm., 11: 14584-14587. PMID32042062: PMCID: PMC7010799
b. Deng, S., Pan, B., Gottlieb, L. and Marmorstein, R. Molecular basis for N-terminal alpha-synuclein acetylation by human NatB. (2020) eLife. 9: e57491. PMID32885784
Deng, S., Gottlieb, L., Pan, B., Supplee, J., Wei, Xuepeng, Petersson, E.J. and Marmorstein, R., Molecular mechanism of N-terminal acetylation by the ternary NatC complex. (2021) Structure, S0969-2126. PMID34019809
Gottlieb, L., Guo, L., Shorter, J. and Marmorstein, R. N-alpha-acetylation of Huntingtin protein increases its propensity to aggregate. (2021) J. Biol. Chem., 31: 101363-. PMID34732320

2. My laboratory is studying the molecular basis for how chromatin is assembled and maintain by histone chaperone complexes. We have focused on the binding and histone deposition of H3/H4 complexes by the ASF1 and VPS75 proteins and the multi-subunit HIRA complex, which specifically deposits the histone H3 variant, H3.3, in a replication independent manner. Histone H3.3 is deposited at active genes, after DNA repair and in certain forms of heterochromatin in non-proliferating senescent cells, and recurrent H3.3 mutations are found in pediatric glioblastoma and dysregulation of H3.3-specific activities in tumor growth and leukemia exemplifies the necessity for proper regulation of H3.3-specific deposition pathways. Together with the Peter Adams laboratory we have pioneered a molecular understanding of the HIRA complex highlighting the particular importance of the HIRA and Ubn1 subunits of H3.3-specific activities.
a. Ricketts, M.D., Frederick, B., Hoff. H., Tang, Y., Schultz, D.C. Rai, T.S., Vizioli, M.G. Adams, P.D. and Marmorstein, R. Ubinuclein-1 confers histone H3.3-specific binding specificity by the HIRA histone chaperone complex. (2015) Nature Commun. 6:7711-. PMID: 26159857: PMCID: PMC4509171
b. Haigney, A., Ricketts, M. D. and Marmorstein, R. Dissecting the Molecular Roles of Histone Chaperones in Histone Acetylation by Type B Histone Acetyltransferases (HAT-B), (2015) J. Biol. Chem., 290:30648-30657. PMID: 26522166: PMCID: PMC4683284
c. Ray-Gallet, D., Ricketts, M.D., Sato, Y., Gupta, K., Boyarchuk, E., Senda, T., Marmorstein, R., and Almouzni, G. Functional activity of the H3.3 histone chaperone complex HIRA requires trimerization of the HIRA subunit. (2018) Nat. Commun. 9:3103. PMID:30082790: PMCID: PMC6078998
d. Ricketts, M.D., Dasgupta, N., Fan, J., Han, J., Gerace, M., Tang, Y., Black, B.E., Adams, P.D. and Marmorstein, R. The HIRA histone chaperone complex subunit UBN1 harbors H3/H4 and DNA binding activity. (2019) J. Biol. Chem., 294: 9239-9259. PMID:31040182; PMCID: PMC6556585

3. My laboratory has leveraged our expertise in biochemistry and X-ray crystallography with small molecule screening for structure-based Inhibitor development for therapy of melanoma and other cancers. There is a particular interest in melanoma and the laboratory had developed inhibitors to several important oncogenic kinases in melanoma including BRAF, PI3K, PAK1 and S6K1. The laboratory has also targeted the oncoproteins E7 and E6 from human papillomavirus (HPV), the causative agent of a number of epithelial cancers, and a significant portion of head and neck cancers. These studies have important implications for therapy.
a. Qin, J., Rajaratnam, R., Feng, L., Salami, J., Barber-Rotenberg, J.S., Domsic, J., Reyes-Uribe, P., Liu, H., Dang, W., Berger, S.L., Villanueva, J., Meggers, E. and Marmorstein, R. Development of organometallic S6K1 inhibitors. (2015) J. Med. Chem. 58:305-314. PMID: 25356520; PMCID: PMC4289024
b. Grasso, M., Estrada, M.A., Ventocilla, C., Samanta, M., Maksimoska, J., Villanueva, J., Winkler, J.D. and Marmorstein, R. Chemically linked vemurafenib inhibitors promote an inactive BRAFV600E conformation. (2016) ACS Chem. Biol. 11: 2876-2888. PMID: 27571413: PMCID: PMC5108658
c. Emtage, R.P., Schoeberger, M.J. Fergusion, K.M., and Marmorstein, R. Intramolecular autoinhibition of Checkpoint Kinase 1 is mediated by conserved basic motifs of the C-terminal Kinase Associated-1 domain. (2017) J. Biol. Chem. 292:19024-19033. PMID:28972186: PMCID: PMC5704483
d. Grasso, M., Estrada, M.A., Berrios, K.N., Winkler, J.D. and Marmorstein, R. N-(7-Cyano-6-(4-fluro-3-(2-(3-(trifluoromethyl)phenyl)acetamido)phenoxy)benzo[d]thiazol-2-yl)cyclopropanecarboxamide (TAK632) promotes inhibition of BRAF through the induction of inhibited dimers. (2018) J. Med. Chem. 61:5034-5046. PMID: 29727562: PMCID: PMC6540792

4. My laboratory has more recently studied the connection between metabolism with cancer signaling and chromatin regulation, with a particular focus on the acetyl-CoA metabolism and metabolite acylation enzymes such as ATP citrate lyase (ACLY). Our studies uncovered the molecular mechanism of ACLY and provided a molecular scaffold for the structure-based development of ACLY inhibitors for therapy of cancer and metabolic and cardiovascular disorders.
a. Bazilevsky, G.A., Affronti, H.C., Wei, X., Campbell, S.L., Wellen, K.E. and Marmorstein. R. ATP-citrate lyase multimerization is required for coenzyme-A substrate binding and catalysis, (2019) J. Biol. Chem. 294:7529-7268. PMID: 30877197; PMCID: PMC6509486
b. Wei, X., Schultz, K., Bazilevsky, G.A., Vogt, A. and Marmorstein R. Molecular basis of acetyl-CoA production by ATP-citrate lyase. (2020) Nature Structural & Molecular Biology 27:33-41. PMID: 31873304
Wei, X. and Marmorstein, R., Reply to: Acetyl-CoA is produced by the citrate synthetase homology module of ATP-citrate lyase. (2021) Nat. Struct. Mol. Biol., 28: 639-641. PMID34294921
Wei, X., Kixmoeller, K., Baltrusaitis, E., Yang, X. and Marmorstein, R. Allosteric role of a structural NADP+ molecule in glucose-6-phosphate dehydrogenase activity, (2022) Proc. Nat. Acad. Sci. USA, 119(29): e2119695119

Research Interest

The Marmorstein laboratory studies the molecular mechanisms of (1) epigenetic regulation (2) protein post- and co-translational modification with a particular focus on protein acetylation, and (3) enzyme signaling in cancer and metabolism. The laboratory uses a broad range of biochemical, biophysical and structural research tools (X-ray crystallography and cryo-EM) to determine macromolecular structure and mechanism of action. The laboratory also uses high-throughput small molecule screening and structure-based design strategies to develop protein-specific small-molecule probes to interrogate protein function and for preclinical studies.

Jennifer E. Phillips-Cremins, Ph.D.

Contributions to Science

The Cremins Lab focuses on higher-order genome folding and how chromatin works through long-range, spatial mechanisms to govern neural specification and synaptic plasticity in healthy and diseased neural circuits. We have developed molecular and computational technologies to create kilobase-resolution maps of chromatin folding and have built synthetic architectural proteins to engineer loops with light, together catalyzing new understanding of the genome’s structure-function relationship. We applied our technologies to discover that topologically associating domains (TADs), nested subTADs, and loops undergo marked reconfiguration during neural lineage commitment, somatic cell reprogramming, neuronal activity stimulation, and in models of repeat expansion disorders. We have demonstrated that loops induced by neural circuit activation, engineered through synthetic architectural proteins, and miswired in fragile X syndrome (FXS) are tightly connected to transcription, thus providing early insight into the genome’s structure-function relationship. Moreover, we have also demonstrated that cohesin-mediated loop extrusion can position the location of human replication origins which fire in early S phase, revealing a role for genome structure beyond gene expression in DNA replication. Recently, we have discovered that nearly all unstable short tandem repeat tracts in trinucleotide expansion disorders are localized to the boundaries between TADs, suggesting they are hotspots for pathological instability. We have identified that Mb-scale H3K9me3 domains decorating autosomes and the X chromosome in FXS are exquisitely sensitive to the length of the CGG STR tract. H3K9me3 domains spatially connect via inter-chromosomal interactions to silence synaptic genes and stabilize STRs prone to instability on autosomes. Together, our work uncovers a link between subMegabase-scale genome folding and genome function in the mammalian brain, thus providing the foundation upon which we will dissect the functional role for chromatin mechanisms in governing defects in synaptic plasticity and long-term memory in currently intractable and poorly understood neurological disorders.

Research Interest

The Cremins lab aims to understand how chromatin works through long-range physical folding mechanisms to encode neuronal specification and long-term synaptic plasticity in healthy and diseased neural circuits. We pursue a multi-disciplinary approach integrating data across biological scales in the brain, including molecular Chromosome-Conformation-Capture sequencing technologies, single-cell imaging, optogenetics, genome engineering, induced pluripotent stem cell differentiation to neurons/organoids, and in vitro and in vivo electrophysiological measurements.

Our long-term scientific goal is to dissect the fundamental mechanisms by which chromatin architecture causally governs genome function and, ultimately, long-term synaptic plasticity and neural circuit features in healthy mammalian brains as well as during the onset and progression of neurodegenerative and neurodevelopmental disease states

Our long-term mentorship goal is to develop a diverse cohort of next-generation scientific thinkers and leaders cross-trained in molecular and computational approaches. We seek to create a positive, high-energy environment with open and honest communication to empower individuals to discover and refine their purpose and grow into the best versions of themselves.

Arjun-Raj

Arjun Raj, Ph.D.

Contribution to Science

We have contributed to the understanding of mechanisms that create and control cell-to-cell variability in gene expression. In particular, our work was amongst the first to use quantitative single molecule RNA detection techniques to describe the phenomenon of transcriptional bursts, in which we found that transcription is a pulsatile process consisting of pulses of activity interspersed with periods when the gene is completely inactive (Raj et al. PLOS Bio 2006, Leveque and Raj Nat Meth 2013a). We also contributed to the mathematical modeling of this field (Raj et al. PLOS Bio 2006). We have now shown how these pulses relate to homeostatic mechanisms that maintain transcript concentration despite changes in cell volume and DNA content (Padovan-Merhar et al. Mol Cell 2015). We have also shown that variability can be used as a tool for dissecting mechanisms of transcriptional control of molecules such as long non-coding RNA (Maamar et al. Genes and Dev. 2013).

Raj A, Peskin CS, Tranchina D, Vargas DY, Tyagi S. Stochastic mRNA synthesis in mammalian cells.PLoS Biol. 2006 Oct;4(10):e309. PubMed PMID: 17048983; PubMed Central PMCID: PMC1563489.
Levesque MJ, Raj A. Single-chromosome transcriptional profiling reveals chromosomal gene expression regulation. Nat Methods. 2013 Mar;10(3):246-8. doi: 10.1038/nmeth.2372. Epub 2013 Feb 17. Erratum in: Nat Methods. 2013 May;10(5):445. PubMed PMID: 23416756; PubMed Central PMCID: PMC4131260.
Maamar H, Cabili MN, Rinn J, Raj A. linc-HOXA1 is a noncoding RNA that represses Hoxa1 transcription in cis. Genes Dev. 2013 Jun 1;27(11):1260-71. doi: 10.1101/gad.217018.113. Epub 2013 May 30. PubMed PMID: 23723417; PubMed Central PMCID: PMC3690399.
Padovan-Merhar O, Nair GP, Biaesch AG, Mayer A, Scarfone S, Foley SW, Wu AR, Churchman LS, Singh A, Raj A. Single Mammalian Cells Compensate for Differences in Cellular Volume and DNA Copy Number through Independent Global Transcriptional Mechanisms. Mol Cell. 2015 Apr 16;58(2):339-52. doi: 10.1016/j.molcel.2015.03.005. Epub 2015 Apr 9. PubMed PMID: 25866248; PubMed Central PMCID: PMC4402149.

We have contributed to the understanding of how cell-to-cell variability can lead to phenotypic consequences. Specifically, we showed that variability in transcription can lead to random cell fate decisions in bacteria (Maamar and Raj et al. Science 2008), and that variability in gene expression can lead to phenotypic variability in metazoan development (Raj and Rifkin et al. Nature 2010). More recently, we have linked gene expression variability to single cell non-genetic resistance mechanisms in melanoma (Shaffer et al. Nature, in press).

Maamar H, Raj A, Dubnau D. Noise in gene expression determines cell fate in Bacillus subtilis. Science. 2007 Jul 27;317(5837):526-9. Epub 2007 Jun 14. PubMed PMID: 17569828; PubMed Central PMCID: PMC3828679.
Raj A, Rifkin SA, Andersen E, van Oudenaarden A. Variability in gene expression underlies incomplete penetrance. Nature. 2010 Feb 18;463(7283):913-8. doi: 10.1038/nature08781. PubMed PMID: 20164922; PubMed Central PMCID: PMC2836165.
Shaffer SM, Dunagin M, Torborg S, Torre EA, Emert T, Krepler C, Beqiri M, Sproesser K, Brafford P, Xiao M, Eggan E, Anastopoulos IN, Vargas-Garcia CA, Singh A, Nathanson K, Heryn M, Raj A. Rare cell variability and drug-induced reprogramming as a mode of cancer drug resistance. Nature, in press.

We have contributed to methodological approaches to measuring expression and transcription in single cells via RNA fluorescence in situ hybridization (RNA FISH). First, we developed a method that greatly simplifies the detection of individual RNA molecules by RNA FISH (Raj et al. Nat Meth 2008). We have since pushed the method to high multiplexing in the detection of chromosome structure and gene expression simultaneously (Levesque and Raj, Nat Meth 2013a). We also have enabled the detection of single nucleotide variants on individual RNA molecules (Levesque et al. Nat Meth 2013b), which allows for mutation detection and measurements of allele-specific expression. Further, we have developed an ultra-fast variant of RNA FISH that enables use in diagnostic and point of care settings (Shaffer et al. PLOS ONE 2013).

Raj A, van den Bogaard P, Rifkin SA, van Oudenaarden A, Tyagi S. Imaging individual mRNA molecules using multiple singly labeled probes. Nat Methods. 2008 Oct;5(10):877-9. doi: 10.1038/nmeth.1253. Epub 2008 Sep 21. PubMed PMID: 18806792; PubMed Central PMCID: PMC3126653.
Levesque MJ, Raj A. Single-chromosome transcriptional profiling reveals chromosomal gene expression regulation. Nat Methods. 2013 Mar;10(3):246-8. doi: 10.1038/nmeth.2372. Epub 2013 Feb 17. Erratum in: Nat Methods. 2013 May;10(5):445. PubMed PMID: 23416756; PubMed Central PMCID: PMC4131260.
Levesque MJ, Ginart P, Wei Y, Raj A. Visualizing SNVs to quantify allele-specific expression in single cells. Nat Methods. 2013 Sep;10(9):865-7. doi: 10.1038/nmeth.2589. Epub 2013 Aug 4. PubMed PMID: 23913259; PubMed Central PMCID: PMC3771873.
Shaffer SM, Wu MT, Levesque MJ, Raj A. Turbo FISH: a method for rapid single molecule RNA FISH. PLoS One. 2013 Sep 16;8(9):e75120. doi: 10.1371/journal.pone.0075120. eCollection 2013. PubMed PMID: 24066168; PubMed Central PMCID: PMC3774626.

Research Interest

Our lab aims to develop a quantitative understanding of the molecular biology of the cell. Interests include chromosome structure and gene expression, non-coding RNA, and global regulation of gene expression. Applications include genetics, cancer and stem cells.

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