title: LKB1/AMPK and PKA control ABCB11 trafficking and polarization in hepatocytes.
abstract: Polarization of hepatocytes is manifested by bile canalicular network formation and activation of LKB1 and AMPK, which control cellular energy metabolism. The bile acid, taurocholate, also regulates development of the canalicular network through activation of AMPK. In the present study, we used collagen sandwich hepatocyte cultures from control and liver-specific LKB1 knockout mice to examine the role of LKB1 in trafficking of ABCB11, the canalicular bile acid transporter. In polarized hepatocytes, ABCB11 traffics from Golgi to the apical plasma membrane and endogenously cycles through the rab 11a-myosin Vb recycling endosomal system. LKB1 knockout mice were jaundiced, lost weight and manifested impaired bile canalicular formation and intracellular trafficking of ABCB11, and died within three weeks. Using live cell imaging, fluorescence recovery after photobleaching (FRAP), particle tracking, and biochemistry, we found that LKB1 activity is required for microtubule-dependent trafficking of ABCB11 to the canalicular membrane. In control hepatocytes, ABCB11 trafficking was accelerated by taurocholate and cAMP; however, in LKB1 knockout hepatocytes, ABCB11 trafficking to the apical membrane was greatly reduced and restored only by cAMP, but not taurocholate. cAMP acted through a PKA-mediated pathway which did not activate AMPK. Our studies establish a regulatory role for LKB1 in ABCB11 trafficking to the canalicular membrane, hepatocyte polarization, and canalicular network formation.
authors.affiliation: Cell Biology and Metabolism Program, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland, United States of America; Laboratory of Molecular Cell Biology, Institute of Molecular Pharmacology, Research Centre for Natural Sciences, Hungarian Academy of Sciences, Budapest, Hungary.
authors.forename: László
authors.initials: L
authors.lastname: Homolya
authors.affiliation: Cell Biology and Metabolism Program, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland, United States of America; Faculty of Pharmacy, The University of Sydney, Sydney, Australia.
authors.forename: Dong
authors.initials: D
authors.lastname: Fu
authors.affiliation: Cell Biology and Metabolism Program, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland, United States of America.
authors.forename: Prabuddha
authors.initials: P
authors.lastname: Sengupta
authors.affiliation: Cell Biology and Metabolism Program, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland, United States of America.
authors.forename: Michal
authors.initials: M
authors.lastname: Jarnik
authors.affiliation: Laboratory of Cell Biology, National Cancer Institute, National Institutes of Health, Bethesda, Maryland, United States of America; Laboratory of Molecular Cancer Biology, Molecular Physiology Research Unit - URPhyM, Namur Research Institute for Life Sciences (NARILIS), Faculty of Medicine, University of Namur, Belgium University of Namur, Belgium.
authors.forename: Jean-Pierre
authors.initials: JP
authors.lastname: Gillet
authors.affiliation: Oral and Pharyngeal Cancer Branch, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, Maryland, United States of America.
authors.forename: Lynn
authors.initials: L
authors.lastname: Vitale-Cross
authors.affiliation: Oral and Pharyngeal Cancer Branch, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, Maryland, United States of America.
authors.forename: J Silvio
authors.initials: JS
authors.lastname: Gutkind
authors.affiliation: Cell Biology and Metabolism Program, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland, United States of America.
authors.forename: Jennifer
authors.initials: J
authors.lastname: Lippincott-Schwartz
authors.affiliation: Cell Biology and Metabolism Program, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland, United States of America.
authors.forename: Irwin M
authors.initials: IM
authors.lastname: Arias
mesh_terms: D055372:AMP-Activated Protein Kinases / Q000235:genetics* / Q000378:metabolism; D000074020:ATP Binding Cassette Transporter, Subfamily B, Member 11; D018528:ATP-Binding Cassette Transporters / Q000235:genetics* / Q000378:metabolism; D000818:Animals; D001647:Bile Acids and Salts / Q000378:metabolism; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism; D016764:Cell Polarity; D000242:Cyclic AMP / Q000378:metabolism / Q000494:pharmacology; D017868:Cyclic AMP-Dependent Protein Kinases / Q000235:genetics* / Q000378:metabolism; D011992:Endosomes / Q000187:drug effects / Q000378:metabolism; D005786:Gene Expression Regulation; D006056:Golgi Apparatus / Q000187:drug effects / Q000378:metabolism; D022781:Hepatocytes / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D051379:Mice; D018345:Mice, Knockout; D024701:Myosin Type V / Q000235:genetics / Q000378:metabolism; D061251:Primary Cell Culture; D017346:Protein Serine-Threonine Kinases / Q000172:deficiency / Q000235:genetics*; D021381:Protein Transport; D015398:Signal Transduction; D013656:Taurocholic Acid / Q000378:metabolism / Q000494:pharmacology; D020691:rab GTP-Binding Proteins / Q000235:genetics / Q000378:metabolism; D000099193:rab11 GTP-Binding Proteins
chemical_list: D055372:AMP-Activated Protein Kinases; D000074020:ATP Binding Cassette Transporter, Subfamily B, Member 11; D018528:ATP-Binding Cassette Transporters; D001647:Bile Acids and Salts; D000242:Cyclic AMP; D017868:Cyclic AMP-Dependent Protein Kinases; D024701:Myosin Type V; D017346:Protein Serine-Threonine Kinases; D013656:Taurocholic Acid; D020691:rab GTP-Binding Proteins; D000099193:rab11 GTP-Binding Proteins; C490549:Abcb11 protein, mouse; C491654:Stk11 protein, mouse