We propose that both human cancers and birth defects are caused by defects in stem cell pluripotency and self-renewal. Tumor formation is theorized to often be the result of oncogenic transformation of normal stems into cancer stem cells. Birth defects are due to disruptions of the pluripotency and self-renewal of stem cells, including inner cell mass cells that are very similar embryonic stem cells (ESC). The molecular mechanisms that cause these stem cell changes leading to human disease remain an open question, but the myc gene family is linked to both human birth defects and cancers suggesting Myc proteins may play key roles in both diseases. We are particularly interested in the specific roles that Myc proteins play in stem cells that lead to human birth defects and cancers. The proposed studies will address the issue of how a single class of proteins, the Myc family, can be so essential for stem cell biology and embryogenesis at normal levels, but in excess cause cancer and produce induced pluripotent stem (iPS) cells. Using proteomics, we have identified three novel Myc cofactors that may direct its function in ESC: histone deacetylases (HDACs);the DNA methyltransferases, DNMT3;and the ESC-specific transcription factor, UTF1. Myc proteins have no known cofactors in ESC or iPS cells, representing a serious gap in the field that our work will bridge. By analyzing the biochemical properties of these protein-protein interactions as well as the nature of how they form on DNA to regulate transcription, the proposed work will provide key insight into Myc function in maintaining pluripotency in ESC and establishing pluripotency in iPS cells. Innovative aspects of the proposal include a new model of how Myc functions as transcription factor including a widespread, repressive function, novel proteomics studies on Myc complexes in stem cells, studies on iPS cells, and analyzing the function of UTF1. When these studies are complete we will have a clearer understanding of the molecular mechanisms that control pluripotency as well as human development and how when disrupted these events lead to human disease.

Public Health Relevance

The objective of the proposed is to elucidate the stem cell-related causes of human birth defects and cancers, thereby opening the door to new treatments and preventative measures. Thus, it has great significance for human health. We also aim to facilitate the development of safe and effective regenerative medicine therapies based on embryonic and induced pluripotent stem cells (ESC, iPS cells). In this way, our studies also may advance one of the most cutting edge approaches to treating and curing human diseases.

National Institute of Health (NIH)
National Institute of General Medical Sciences (NIGMS)
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Special Emphasis Panel (ZRG1-BDA-P (90))
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Haynes, Susan R
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University of California Davis
Anatomy/Cell Biology
Schools of Medicine
United States
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Klein, Rachel Herndon; Tung, Po-Yuan; Somanath, Priyanka et al. (2018) Genomic functions of developmental pluripotency associated factor 4 (Dppa4) in pluripotent stem cells and cancer. Stem Cell Res 31:83-94
Somanath, Priyanka; Bush, Kelly M; Knoepfler, Paul S (2018) ERBB3-Binding Protein 1 (EBP1) Is a Novel Developmental Pluripotency-Associated-4 (DPPA4) Cofactor in Human Pluripotent Cells. Stem Cells 36:671-682
Somanath, Priyanka; Herndon Klein, Rachel; Knoepfler, Paul S (2017) CRISPR-mediated HDAC2 disruption identifies two distinct classes of target genes in human cells. PLoS One 12:e0185627
Martínez-Cerdeño, Veronica; Barrilleaux, Bonnie L; McDonough, Ashley et al. (2017) Behavior of Xeno-Transplanted Undifferentiated Human Induced Pluripotent Stem Cells Is Impacted by Microenvironment Without Evidence of Tumors. Stem Cells Dev 26:1409-1423
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Knoepfler, Paul S (2015) From bench to FDA to bedside: US regulatory trends for new stem cell therapies. Adv Drug Deliv Rev 82-83:192-6
Tung, P-Y; Knoepfler, P S (2015) Epigenetic mechanisms of tumorigenicity manifesting in stem cells. Oncogene 34:2288-96
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Yuen, Benjamin T K; Bush, Kelly M; Barrilleaux, Bonnie L et al. (2014) Histone H3.3 regulates dynamic chromatin states during spermatogenesis. Development 141:3483-94
Knoepfler, Paul S (2013) Scientists: you really need to get out of the lab more. Nat Med 19:1086

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