The PTH-G alpha(s)-Protein Kinase A Cascade Controls alpha NAC Localization To Regulate Bone Mass MOLECULAR AND CELLULAR BIOLOGY Pellicelli, M., Miller, J. A., Arabian, A., Gauthier, C., Akhouayri, O., Wu, J. Y., Kronenberg, H. M., St-Arnaud, R. 2014; 34 (9): 1622-1633

Abstract

The binding of PTH to its receptor induces Gas-dependent cAMP accumulation to turn on effector kinases, including protein kinase A (PKA). The phenotype of mice with osteoblasts specifically deficient for Gas is mimicked by a mutation leading to cytoplasmic retention of the transcriptional coregulator aNAC, suggesting that Gas and aNAC form part of a common genetic pathway. We show that treatment of osteoblasts with PTH(1-34) or the PKA-selective activator 6Bnz-cAMP lead to translocation of aNAC to the nucleus. aNAC was phosphorylated by PKA at serine 99 in vitro. Phospho-S99-aNAC accumulated in osteoblasts exposed to PTH(1-34) or 6Bnz-cAMP but not in treated cells expressing dominant negative PKA. Nuclear accumulation was abrogated by an S99A mutation but enhanced by a phosphomimetic residue (S99D). ChIP analysis showed that PTH(1-34) or 6Bnz-cAMP treatment leads to accumulation of aNAC at the Osteocalcin (Ocn) promoter. Altered gene dosage for Gas and aNAC in compound heterozygous mice results in reduced bone mass, increased numbers of osteocytes, and enhanced expression of Sost. Our results show that aNAC is a substrate of PKA following PTH signaling. This enhances aNAC translocation to the nucleus and leads to its accumulation at target promoters to regulate transcription and affect bone mass.

View details for DOI 10.1128/MCB.01434-13

View details for Web of Science ID 000334316300007

View details for PubMedID 24550008