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Functional interaction of transcriptional regulators in endocrine lineage specification

内分泌谱系规范中转录调节因子的功能相互作用

基本信息

批准号：
10577702
负责人：
Maureen A Gannon
金额：
$ 75.47万
依托单位：
UNIVERSITY OF PENNSYLVANIA
依托单位国家：
美国
项目类别：
财政年份：
2023
资助国家：
美国
起止时间：
2023-01-01 至 2027-12-31
项目状态：
未结题

来源：
https://reporter.nih.gov/project-details/10577702
关键词：
3-Dimensional ATAC-seq Beta Cell Biophysics C-terminal Cell Cycle Cell Cycle Progression Cell Line Cell Therapy Cell physiology Chromatin Compensation Complex Consensus Data Development Diabetes Mellitus Disease Endocrine Enhancers Epigenetic Process Exhibits Failure Gene Expression Regulation Genes Genetic Genetic Transcription Glucose Growth Heterozygote Human In Vitro Intervention Islets of Langerhans Mediating Microscopy Molecular Molecular Conformation Mus Mutagenesis Mutate Mutation Non-Insulin-Dependent Diabetes Mellitus Organ Size Organogenesis Pancreas Pathway interactions Phase Phenotype Phosphorylation Site Play Post-Translational Protein Processing Proliferating Property Protein Region Proteins Publishing Regulation Resolution Role Site Specific qualifier value Stimulus Structure Structure of beta Cell of islet Techniques Testing Therapeutic Ubiquitination Work design endocrine pancreas development flexibility genome editing homeodomain human embryonic stem cell human pluripotent stem cell in vivo insulin promoter factor 1 insulin secretion intermolecular interaction islet islet stem cells member mimetics mouse model multiple omics novel overexpression pancreas development permissiveness postnatal prediction algorithm prevent progenitor programs promoter protein protein interaction response single nucleus RNA-sequencing single-cell RNA sequencing stem cell differentiation transcription factor ubiquitin-protein ligase

项目摘要

SUMMARY Reduction in functional insulin-secreting β cells underlies the progression of all forms of diabetes, underscoring the translational relevance of deciphering molecular pathways regulating the formation, growth, and function of β cells. The transcriptional networks critical for the proper development, differentiation, and expansion of β cells work through islet enhancers, super enhancers, and active promoters that form 3D hubs. The homeodomain transcription factor Pdx1 is a critical member of the β-cell transcriptional network during development and in postnatal β-cell function. Pdx1 is mutated in monogenic forms of human diabetes and plays critical roles in early pancreas specification, regulation of organ size, and in β-cell formation, proliferation, and identity. Our preliminary data reveal that developing β cells exhibit altered subnuclear localization and reduced levels of Pdx1 protein as they advance through the cell cycle. Further, ectopically elevated levels of Pdx1 prevent cell cycle progression, suggesting that dynamic regulation of expression is required for effective β-cell expansion. We identify an intrinsically disordered protein region (IDPR) in the Pdx1 C-terminus (aa 207-223). IDPRs, commonly found within transcription factors, lack fixed secondary structure and are amenable to flexible conformations and phase separation. IDPRs promote protein-protein interactions and transcriptional hub formation at super enhancers necessary for coordinated gene regulation. We have found that the Pdx1 C-terminus mediates interaction with the one cut homeodomain transcription factor Oc1 in multipotent pancreatic progenitor cells to establish the endocrine gene program, with long-term impact on postnatal islet function and β-cell compensation. We previously identified the E3 ubiquitin ligase substrate adaptor SPOP as a PDX1 C-terminus partner (via aa224-238) that mediates ubiquitination and proteasomal degradation of PDX1. Our preliminary data suggest that SPOP and Oc1 compete for interaction with the Pdx1 C-terminus and that Oc1 protects Pdx1 from SPOP- mediated degradation. Notably, the C-terminus harbors several diabetes-associated human mutations, one of which we recently found disrupts the PDX1/SPOP interaction. Thus, we hypothesize that PDX1/OC1 interactions, in part mediated by their IDPRs, regulate Pdx1 stability, cell cycle progression, and pancreatic endocrine differentiation. This hypothesis will be tested in 3 Aims: (1) To determine the mechanisms whereby Pdx1 and Oc1 cooperate to establish a chromatin landscape permissive for endocrine differentiation and proliferation; (2) To define the roles of the Pdx1 and Oc1 IDPRs in protein-protein interaction and pancreas development; and (3) To define the molecular mechanisms by which the Pdx1 C-terminal domain regulates protein stability and function during pancreas organogenesis and endocrine differentiation. The impact of human diabetes-associated mutations will be investigated in this context. Our studies will determine a novel and cohesive role for unstudied structural features of the Pdx1 C-terminus in β-cell development. Results of our studies will inform therapeutic efforts to optimize β-cell expansion for cell-based therapies.

总结