Regulation of Hepatic Gluconeogenesis by an ER-Bound Transcription Factor, CREBH

다국어 초록 (Multilingual Abstract)

<P><B>Summary</B></P><P>Endoplasmic reticulum (ER)-bound transcription factor families are shown to be involved in the control of various metabolic pathways. Here, we report a critical function of ER-bound transcription factor, CREBH, in the regulation of hepatic gluconeogenesis. Expression of CREBH is markedly induced by fasting or in the insulin-resistant state in rodents in a dexamethasone- and PGC-1α-dependent manner, which results in the accumulation of active nuclear form of CREBH (CREBH-N). Overexpression of constitutively active CREBH activates transcription of <I>PEPCK-C</I> or <I>G6Pase</I> by binding to its enhancer site that is distinct from the well-characterized CREB/CRTC2 regulatory sequences in vivo. Of interest, knockdown of CREBH in liver significantly reduces blood glucose levels without altering expression of genes involved in the ER stress signaling cascades in mice. These data suggest a crucial role for CREBH in the regulation of hepatic glucose metabolism in mammals.</P> <P><B>Highlights</B></P><P>► PGC-1α/GR activates CREBH expression under fasting or insulin-resistant conditions ► CREBH enhances hepatic gluconeogenesis via a CRTC2-dependent manner ► Depletion of CREBH in the liver ameliorates fasting hyperglycemia in diabetic mice</P>