AKAP350 is involved in the development of apical “canalicular” structures in hepatic cells HepG2

MATTALONI SM ; KOLOBOVA E; FAVRE C; MARINELLI RA; GOLDENRING JR; LAROCCA MC

JOURNAL OF CELLULAR PHYSIOLOGY

WILEY-LISS, DIV JOHN WILEY & SONS INC

Año: 2011

0021-9541

Hepatocytes are epithelial cells whose apical poles constitute the bile canaliculi. The establishment and maintenance of canalicular poles is a finely regulated process that dictates the efficiency of primary bile secretion. Protein kinase A (PKA) modulates this process at different levels. AKAP350 is an A-kinase anchoring protein that scaffolds protein complexes involved in modulating the dynamic structures of the Golgi apparatus and microtubule cytoskeleton, facilitating microtubule nucleation at this organelle. In this study, we evaluated whether AKAP350 is involved in bile canaliculi biogenesis in hepatocyte derived HepG2 cells. We found that AKAP350 recruits PKA to the centrosomes and Golgi apparatus in HepG2 cells. De-localization of AKAP350 from these organelles led to reduced apical cell polarization. A decrease in AKAP350 expression inhibited canalicular formation and F-actin organization at the canaliculi, effects that could be mimicked by inhibition of Golgi microtubule nucleation by depletion of CLASP proteins.   Loss of AKAP350 expression led to diminished polarized expression of the p-glycoprotein at the canaliculi. Our data reveal that AKAP350 participates in mechanisms, which determine the de novo formation of bile canaliculi as well as accurate canalicular expression of distinct proteins and actin organization, and suggest the involvement of Golgi microtubule nucleation in apical polarity development in hepatocytes.