Failure of insulin secreting pancreatic islet ? cells is a hallmark of both type1 and type 2 diabetes, leading to this laboratory's intense focus on molecular mechanisms regulating pancreatic ? cell development and function. We previously identified Pcif1 in a yeast two hybrid screen for partners of Pdx1, a homeodomain transcription factor and human diabetes gene pivotally positioned in the transcriptional hierarchy governing the development of ? cell mass, the function and survival of adult ? cells, and the ability of adult ? cells to compensate for increased metabolic demand imposed by insulin resistance. During the previous funding period we determined that Pcif1 acts at least in part through its role as a substrate adaptor to recruit Pdx1 into a cullin3-based complex for ubiquitination and proteasomal degradation, thereby implicating Pcif1 as a target for regulating Pdx1 levels. Indeed, Pcif1 loss of function in ? cells elevates Pdx1 protein and stimulates expression of important Pdx1 transcriptional targets, including insulin, MafA and Glut2. In vivo genetic disruption of Pcif1 reveals roles in regulating adult ? cell turnover and function and in endocrine lineage allocation during embryonic development, through Pdx1-dependent and, likely, Pdx1-independent mechanisms. We hypothesize that Pcif1 critically regulates embryonic ? cell formation and the adult ? cell cycle through its ability to modulate the levels/functions of key transcriptional regulators. This hypothesis will be tested in two aims:
Aim 1. To determine how Pcif1 regulates the turnover of adult ? cells, and Aim 2. To determine how Pcif1 influences the emergence of the ? cell lineage during embryonic pancreas development. Insights gained from the proposed experiments will provide a conceptual scaffold for the development of targeted therapeutics that interfere with Pcif1 expression or its interactions with critical substrates in the ? cell to influence ? cell mass and ? cell function, with potential application to approaches involving stem cell differentiation to ? cells, cellular reprogramming of ? cells from other mature cell types, and for approaches to promote the function and regeneration of endogenous beta cell mass in patients with diabetes.

Public Health Relevance

Failure of insulin secreting pancreatic islet ? cells is a hallmark of both type1 and type 2 diabetes, prompting intense effort to develop new sources of insulin- producing ? cells for replacement therapies and new ways to promote endogenous ? cell regeneration. The proposed studies will address important questions about the functions of the ubiquitin ligase substrate adaptor Pcif1 in ? cell biology. Insights gained will provide a conceptual scaffold for the development of targeted therapeutics that interfere with Pcif1 expression or its interactions with critical substrates in the ? cell to influence ? cell mass and ? cell function, with potential application to stem cell differentiation, cellular reprogramming and approaches to promote the function and regeneration of endogenous ? cell mass in patients with diabetes.

Agency
National Institute of Health (NIH)
Institute
National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)
Type
Research Project (R01)
Project #
5R01DK068157-08
Application #
8292185
Study Section
Cellular Aspects of Diabetes and Obesity Study Section (CADO)
Program Officer
Sato, Sheryl M
Project Start
2004-07-01
Project End
2014-06-30
Budget Start
2012-07-01
Budget End
2013-06-30
Support Year
8
Fiscal Year
2012
Total Cost
$374,480
Indirect Cost
$136,231
Name
University of Pennsylvania
Department
Internal Medicine/Medicine
Type
Schools of Medicine
DUNS #
042250712
City
Philadelphia
State
PA
Country
United States
Zip Code
19104
Liew, Chong Wee; Assmann, Anke; Templin, Andrew T et al. (2014) Insulin regulates carboxypeptidase E by modulating translation initiation scaffolding protein eIF4G1 in pancreatic ? cells. Proc Natl Acad Sci U S A 111:E2319-28
Claiborn, Kathryn C; Sachdeva, Mira M; Cannon, Corey E et al. (2010) Pcif1 modulates Pdx1 protein stability and pancreatic ýý cell function and survival in mice. J Clin Invest 120:3713-21
Yang, Yuqing; Gurung, Buddha; Wu, Ting et al. (2010) Reversal of preexisting hyperglycemia in diabetic mice by acute deletion of the Men1 gene. Proc Natl Acad Sci U S A 107:20358-63
Liu, Jiangying; Wang, You; Birnbaum, Morris J et al. (2010) Three-amino-acid-loop-extension homeodomain factor Meis3 regulates cell survival via PDK1. Proc Natl Acad Sci U S A 107:20494-9
Sachdeva, Mira M; Stoffers, Doris A (2009) Minireview: Meeting the demand for insulin: molecular mechanisms of adaptive postnatal beta-cell mass expansion. Mol Endocrinol 23:747-58
Sachdeva, Mira M; Claiborn, Kathryn C; Khoo, Cynthia et al. (2009) Pdx1 (MODY4) regulates pancreatic beta cell susceptibility to ER stress. Proc Natl Acad Sci U S A 106:19090-5
Oliver-Krasinski, Jennifer M; Kasner, Margaret T; Yang, Juxiang et al. (2009) The diabetes gene Pdx1 regulates the transcriptional network of pancreatic endocrine progenitor cells in mice. J Clin Invest 119:1888-98
Oliver-Krasinski, Jennifer M; Stoffers, Doris A (2008) On the origin of the beta cell. Genes Dev 22:1998-2021
Claiborn, Kathryn C; Stoffers, Doris A (2008) Toward a cell-based cure for diabetes: advances in production and transplant of beta cells. Mt Sinai J Med 75:362-71
Liu, Aihua; Oliver-Krasinski, Jennifer; Stoffers, Doris A (2006) Two conserved domains in PCIF1 mediate interaction with pancreatic transcription factor PDX-1. FEBS Lett 580:6701-6

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