Abstract
Prominin-1 (Prom1) is a major cell surface marker of cancer stem cells, but its physiological functions in the liver have not been elucidated. We analyzed the levels of mRNA transcripts in serum-starved primary Prom1+/+ and Prom1-/- mouse hepatocytes using RNA-sequencing (RNA-seq) data, and found that CREB target genes were down-regulated. This initial observation led us to determine that the Prom1 deficiency inhibited cAMP response element binding protein (CREB) activation and gluconeogenesis, but not cyclic AMP (cAMP) accumulation, in glucagon-, epinephrine-, or forskolin-treated liver tissues and primary hepatocytes, and mitigated glucagon-induced hyperglycemia. Because Prom1 interacted with radixin, the Prom1 deficiency prevented radixin from localizing to the plasma membrane. Moreover, systemic adenoviral knockdown of radixin inhibited CREB activation and gluconeogenesis in glucagon-treated liver tissues and primary hepatocytes, and mitigated glucagon-elicited hyperglycemia. Based on these results, we conclude that Prom1 regulates hepatic PKA signaling via radixin functioning as an A kinase-anchored protein (AKAP).
Abbreviations
- AKAP
- A kinase-anchored protein
- AC
- adenylyl cyclase
- cAMP
- cyclic adenosine monophosphate
- PKA
- protein kinase A
- CREB
- cAMP response element binding protein
- pck
- phosphoenol pyruvate carboxykinase
- g6p
- glucose-6-phosphatase
- G6pc
- g6p catalytic subunit
- PI3K
- phosphatidylinositide 3-kinases
- Fbp1
- fructose 1,6-bisphosphatase 1
- GPCR
- G protein– coupled receptor
- PDE
- phosphodiesterase
- IBMX
- 3-isobutyl-1-methylxanthine
- 8-Br-cAMP
- 8-Bromo-cAMP
- DIO
- diet-induced obese
- shRNA
- short hairpin RNA
- FERM
- F for 4.1 protein, E for ezrin, R for radixin and M for moesin
- CFTR
- fibrosis transmembrane conductance regulator
- NHE3
- Na+-H+ exchanger 3
- Cx43
- connexin 43
- EPAC
- exchange protein directrly activated by cAMP