Protein kinase Cδ differentially regulates cAMP-dependent translocation of NTCP and MRP2 to the plasma membrane. 2012

Se Won Park, and Christopher M Schonhoff, and Cynthia R L Webster, and M Sawkat Anwer
Department of Biomedical Sciences, Cummings School of Veterinary Medicine at Tufts University, North Grafton, Massachusetts, USA.

Cyclic AMP stimulates translocation of Na(+)/taurocholate cotransporting polypeptide (NTCP) from the cytosol to the sinusoidal membrane and multidrug resistance-associated protein 2 (MRP2) to the canalicular membrane. A recent study suggested that protein kinase Cδ (PKCδ) may mediate cAMP-induced translocation of Ntcp and Mrp2. In addition, cAMP has been shown to stimulate NTCP translocation in part via Rab4. The aim of this study was to determine whether cAMP-induced translocation of NTCP and MRP2 require kinase activity of PKCδ and to test the hypothesis that cAMP-induced activation of Rab4 is mediated via PKCδ. Studies were conducted in HuH-NTCP cells (HuH-7 cells stably transfected with NTCP). Transfection of cells with wild-type PKCδ increased plasma membrane PKCδ and NTCP and increased Rab4 activity. Paradoxically, overexpression of kinase-dead dominant-negative PKCδ also increased plasma membrane PKCδ and NTCP as well as Rab4 activity. Similar results were obtained in PKCδ knockdown experiments, despite a decrease in total PKCδ. These results raised the possibility that plasma membrane localization rather than kinase activity of PKCδ is necessary for NTCP translocation and Rab4 activity. This hypothesis was supported by results showing that rottlerin, which has previously been shown to inhibit cAMP-induced membrane translocation of PKCδ and NTCP, inhibited cAMP-induced Rab4 activity. In addition, LY294002 (a phosphoinositide-3-kinase inhibitor), which has been shown to inhibit cAMP-induced NTCP translocation, also inhibited cAMP-induced PKCδ translocation. In contrast to the results with NTCP, cAMP-induced MRP2 translocation was inhibited in cells transfected with DN-PKCδ and small interfering RNA PKCδ. Taken together, these results suggest that the plasma membrane localization rather than kinase activity of PKCδ plays an important role in cAMP-induced NTCP translocation and Rab4 activity, whereas the kinase activity of PKCδ is necessary for cAMP-induced MRP2 translocation.

UI MeSH Term Description Entries
D002462 Cell Membrane The lipid- and protein-containing, selectively permeable membrane that surrounds the cytoplasm in prokaryotic and eukaryotic cells. Plasma Membrane,Cytoplasmic Membrane,Cell Membranes,Cytoplasmic Membranes,Membrane, Cell,Membrane, Cytoplasmic,Membrane, Plasma,Membranes, Cell,Membranes, Cytoplasmic,Membranes, Plasma,Plasma Membranes
D005786 Gene Expression Regulation Any of the processes by which nuclear, cytoplasmic, or intercellular factors influence the differential control (induction or repression) of gene action at the level of transcription or translation. Gene Action Regulation,Regulation of Gene Expression,Expression Regulation, Gene,Regulation, Gene Action,Regulation, Gene Expression
D006801 Humans Members of the species Homo sapiens. Homo sapiens,Man (Taxonomy),Human,Man, Modern,Modern Man
D000089762 Multidrug Resistance-Associated Protein 2 An ATP-BINDING CASSETTE TRANSPORTERS subfamily protein that is localized on the canalicular membrane of HEPATOCYTES, as well as on the apical membrane of EPITHELIAL CELLS of the DUODENUM, JEJUNUM and PROXIMAL RENAL TUBULE. ABCC2 Protein,CMOAT,CMOAT Protein,CMOAT Transport Protein,Canalicular Multispecific Organic Anion Transporter,MRP2 Protein, Multidrug Resistance,MRP2 Transport Protein,Multidrug Resistance Protein MRP2,Multidrug-Resistance Associated Protein 2,Multidrug Resistance Associated Protein 2,Transport Protein, CMOAT,Transport Protein, MRP2
D000242 Cyclic AMP An adenine nucleotide containing one phosphate group which is esterified to both the 3'- and 5'-positions of the sugar moiety. It is a second messenger and a key intracellular regulator, functioning as a mediator of activity for a number of hormones, including epinephrine, glucagon, and ACTH. Adenosine Cyclic 3',5'-Monophosphate,Adenosine Cyclic 3,5 Monophosphate,Adenosine Cyclic Monophosphate,Adenosine Cyclic-3',5'-Monophosphate,Cyclic AMP, (R)-Isomer,Cyclic AMP, Disodium Salt,Cyclic AMP, Monoammonium Salt,Cyclic AMP, Monopotassium Salt,Cyclic AMP, Monosodium Salt,Cyclic AMP, Sodium Salt,3',5'-Monophosphate, Adenosine Cyclic,AMP, Cyclic,Adenosine Cyclic 3',5' Monophosphate,Cyclic 3',5'-Monophosphate, Adenosine,Cyclic Monophosphate, Adenosine,Cyclic-3',5'-Monophosphate, Adenosine,Monophosphate, Adenosine Cyclic
D051745 Protein Kinase C-delta A ubiquitously expressed protein kinase that is involved in a variety of cellular SIGNAL PATHWAYS. Its activity is regulated by a variety of signaling protein tyrosine kinase. PKC-delta Serine-Threonine Kinase,Kinase C-delta, Protein,PKC delta Serine Threonine Kinase,Protein Kinase C delta,Serine-Threonine Kinase, PKC-delta
D018929 Cell Culture Techniques Methods for maintaining or growing CELLS in vitro. Cell Culture,Cell Culture Technique,Cell Cultures,Culture Technique, Cell,Culture Techniques, Cell
D020695 rab4 GTP-Binding Proteins A genetically related subfamily of RAB GTP-BINDING PROTEINS involved in recycling of proteins such as cell surface receptors from early endosomes to the cell surface. This enzyme was formerly listed as EC 3.6.1.47. rab4A GTP-Binding Protein,rab4 GTP-Binding Protein,rab4 Protein,rab4A Protein,GTP-Binding Protein, rab4,GTP-Binding Protein, rab4A,GTP-Binding Proteins, rab4,rab4 GTP Binding Protein,rab4 GTP Binding Proteins,rab4A GTP Binding Protein
D021381 Protein Transport The process of moving proteins from one cellular compartment (including extracellular) to another by various sorting and transport mechanisms such as gated transport, protein translocation, and vesicular transport. Cellular Protein Targeting,Gated Protein Transport,Protein Targeting, Cellular,Protein Translocation,Transmembrane Protein Transport,Vesicular Protein Transport,Protein Localization Processes, Cellular,Protein Sorting,Protein Trafficking,Protein Transport, Gated,Protein Transport, Transmembrane,Protein Transport, Vesicular,Traffickings, Protein
D027425 Multidrug Resistance-Associated Proteins A sequence-related subfamily of ATP-BINDING CASSETTE TRANSPORTERS that actively transport organic substrates. Although considered organic anion transporters, a subset of proteins in this family have also been shown to convey drug resistance to neutral organic drugs. Their cellular function may have clinical significance for CHEMOTHERAPY in that they transport a variety of ANTINEOPLASTIC AGENTS. Overexpression of proteins in this class by NEOPLASMS is considered a possible mechanism in the development of multidrug resistance (DRUG RESISTANCE, MULTIPLE). Although similar in function to P-GLYCOPROTEINS, the proteins in this class share little sequence homology to the ATP BINDING CASSETTE TRANSPORTER, SUBFAMILY B, MEMBER 1 family of proteins. Multidrug Resistance-Associated Protein,ATP-Binding Cassette, Sub-Family C Proteins,MOAT Protein,Multispecific Organic Anion Transport Proteins,Multispecific Organic Anion Transporter,ATP Binding Cassette, Sub Family C Proteins,Multidrug Resistance Associated Protein,Multidrug Resistance Associated Proteins,Resistance-Associated Protein, Multidrug

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