Bile acids stimulate PKCautophosphorylation and activation; role in the attenuation of prostaglandin E1-induced cAMP production in human dermal fibroblasts

Le M, Krilov L, Meng J, Chapin-Kennedy K, Ceryak S, Bouscarel B
Source: Am J Physiol Gastrointest Liver Physiol
Publication Date: (2006)
Issue: 291(2): G275-87
Research Area:
Cancer Research/Cell Biology
Cells used in publication:
Fibroblast, dermal (NHDF-Neo), human neonatal
Species: human
Tissue Origin: dermal
Fibroblast, dermal(NHDF-Ad), human adult
Species: human
Tissue Origin: dermal
Nucleofector® I/II/2b
The aim was to identify the specific PKC isoform(s) and their mechanism of activation responsible for the modulation of cAMP production by bile acids in human dermal fibroblasts. Stimulation of fibroblasts with 25-100 microM of chenodeoxycholic acid (CDCA) and ursodeoxycholic acid (UDCA) led to YFP-PKCalpha and YFP-PKCdelta translocation in 30-60 min followed by a transient 24-48h down-regulation of the total PKCalpha, PKCdelta and PKCepsilon protein expression by 30-50%, without affecting that of PKCzeta. Phospho- PKCalpha translocated to the plasma membrane, while phospho-PKCdelta Thr505 and Tyr311translocated to the perinuclear domain and nucleus in particular. The attenuation of cAMP production by CDCA was PKCalpha specific, demonstrated using both inhibitors and PKC isoform DN mutants. Under these same conditions, neither PI3 Kinase, p38 MAP kinase, p42/44 MAP kinase, nor PKA inhibitors had any significant effect on the CDCA-induced cAMP production attenuation. CDCA concentrations as low as 10 microM stimulated PKCalpha autophosphorylation in vitro. This bile acid effect required phosphatidylserine and was completely abolished by the presence of Go6976. CDCA at concentrations less than 50 microM enhanced the PKCalpha activation induced by PMA while greater CDCA concentrations reduced the PMA-induced PKCalpha activation. CDCA alone did not affect PKCalpha activity in vitro. In conclusion, while CDCA and UDCA activate different PKC isoforms, PKCalpha plays a major role in the bile acid-induced inhibition of cAMP synthesis in fibroblasts. This study emphasizes potential consequences of increased systemic bile acid concentrations, and cellular bile acid accumulation in extrahepatic tissues during cholestatic liver diseases.