Point mutations in the PDX1 transactivation domain impair human β-cell development and function.

Area of Science:

• Genetics
• Endocrinology
• Molecular Biology

Background:

• The PDX1 gene is crucial for pancreatic development and beta-cell function.
• Missense mutations in PDX1 are common, but their role in diabetes predisposition is unclear.

Purpose of the Study:

• To investigate the impact of common PDX1 missense mutations on human pancreatic beta-cell differentiation and function.
• To elucidate the mechanisms by which PDX1 mutations contribute to diabetes risk.

Main Methods:

• Generated induced pluripotent stem cells (iPSCs) from patients with heterozygous PDX1 mutations (P33T, C18R).
• Engineered isogenic cell lines with homozygous PDX1 mutations and loss-of-function mutations.
• Utilized an in vitro beta-cell differentiation protocol to assess differentiation efficiency and function.

Main Results:

• Both heterozygous and homozygous PDX1 mutations (P33T, C18R) impaired beta-cell differentiation and function.
• PDX1 mutations reduced pancreatic progenitor cell differentiation by downregulating key genes (MNX1, PDX1, CES1, MEG3, NNAT).
• Affected genes are involved in pancreatic development, insulin resistance, synthesis, and secretion.

Conclusions:

• Common coding mutations in PDX1 mechanistically impair human pancreatic endocrine lineage formation.
• These PDX1 mutations contribute to beta-cell dysfunction and predisposition to diabetes mellitus.