Abstract
The cAMP response element binding protein (CREB) is induced during fasting in the liver, where it stimulates transcription of rate-limiting gluconeogenic genes to maintain metabolic homeostasis. Adenoviral and transgenic CREB reporters have been used to monitor hepatic CREB activity non-invasively using bioluminescence reporter imaging. However, adenoviral vectors and randomly inserted transgenes have several limitations. To overcome disadvantages of the currently used strategies, we created a ROSA26 knock-in CREB reporter mouse line (ROSA26-CRE-luc). cAMP-inducing ligands stimulate the reporter in primary hepatocytes and myocytes from ROSA26-CRE-luc animals. In vivo, these animals exhibit little hepatic CREB activity in the ad libitum fed state but robust induction after fasting. Strikingly, CREB was markedly stimulated in liver, but not in skeletal muscle, after overnight voluntary wheel-running exercise, uncovering differential regulation of CREB in these tissues under catabolic states. The ROSA26-CRE-luc mouse line is a useful resource to study dynamics of CREB activity longitudinally in vivo and can be used as a source of primary cells for analysis of CREB regulatory pathways ex vivo.
Highlights
The cyclic adenosine monophosphate (cAMP) response element binding protein (CREB) is a key transcription factor in the response to endocrine hormones that stimulate G-protein coupled receptors to initiate cAMP signaling [1]
To create ROSA26 knock-in cAMP response element binding protein (CREB) reporter mice, we obtained a validated CREB-activated luciferase reporter plasmid from Promega that contains two full and two half cAMP response elements (CRE) and codon-optimized luc2 fused to a destabilization sequence (PEST) (Fig 1A)
We sub-cloned CRE-luc2PEST into the Ai9 ROSA26 targeting vector, which encodes a CAG-lox-stop-lox-tdTomato transgene that is commonly used as a Cre recombinase reporter [15]
Summary
The cAMP response element binding protein (CREB) is a key transcription factor in the response to endocrine hormones that stimulate G-protein coupled receptors to initiate cAMP signaling [1]. CREB binds directly to cAMP response elements (CRE) on the proximal promoter regions of target genes and recruits co-activators CREB binding protein (CBP) and CREB-regulated transcriptional co-activators (CRTCs) to form a ternary complex in response to cAMP/PKA signaling. Glucagon stimulates CREB transcriptional complex activity that is critical for stimulation of gluconeogenic genes, as mice lacking CREB or CRTC2 activity in liver have defective initiation of gluconeogenic gene transcription upon fasting. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
