CREB regulates hepatic gluconeogenesis through the coactivator PGC-1

Area of Science:

• Metabolic regulation
• Molecular endocrinology
• Gene expression

Background:

• Mammalian fasting triggers gluconeogenesis via glucagon and glucocorticoids.
• The precise molecular mechanism for synergistic induction of glucose synthesis remains unclear.
• Understanding these pathways is vital for metabolic disease research.

Purpose of the Study:

• To elucidate the mechanism by which CREB regulates gluconeogenesis.
• To identify the role of PGC-1 in CREB-mediated glucose homeostasis.
• To investigate the link between CREB, PGC-1, and hepatic gluconeogenesis.

Main Methods:

• Gene disruption and overexpression studies in mice.
• Analysis of gluconeogenic gene expression.
• In vivo CREB regulation assays.
• Transient transfection assays to assess PGC-1 function.

Main Results:

• CREB deficiency or inhibition leads to fasting hypoglycemia and reduced gluconeogenic enzyme expression.
• CREB directly regulates PGC-1 expression in vivo.
• PGC-1 overexpression in CREB-deficient mice restored glucose homeostasis.
• PGC-1 enhances glucocorticoid induction of PEPCK, a key gluconeogenic enzyme.

Conclusions:

• CREB activates the gluconeogenic program through direct regulation of PGC-1.
• PGC-1 acts as a crucial coactivator, integrating cAMP and glucocorticoid signaling for hepatic gluconeogenesis.
• Dysregulation of the CREB-PGC-1 pathway in liver may contribute to the pathogenesis of type II diabetes.