Secreted PDZD2 exerts an insulinotropic effect on INS-1E cells by a PKA-dependent mechanism. 2020

Danny Hon Fai So, and Joe Cho Yan Chan, and Michelle Grace Tsui, and Phyllis Siu Wai Tsang, and Kwok-Ming Yao
School of Biomedical Sciences, The LKS Faculty of Medicine, The University of Hong Kong, Hong Kong.

Secreted PDZD2 (sPDZD2) is a signaling molecule generated upon proteolytic processing of the multi-PDZ-containing protein PDZD2. Previous analysis of gene-trap mice deficient in the synthesis of full-length PDZD2, but not the secreted form, revealed a role of PDZD2 in the regulation of glucose-stimulated insulin secretion. Here, using the pancreatic INS-1E β cells as in vitro model, we showed that depletion of PDZD2/sPDZD2 by RNA interference suppressed the expression of β-cell genes Ins1, Glut2 and MafA whereas treatment with recombinant sPDZD2 rescued the suppressive effect. Similar to GLP-1, sPDZD2 stimulated intracellular cAMP levels, activated β-cell gene expression in a PKA-dependent manner and induced the phosphorylation and nuclear localization of PDX1. Depletion of PDX1 inhibited the sPDZD2 insulinotropic effect, which could also be demonstrated in mouse islets. In summary, our findings are consistent with sPDZD2 serving a signaling function in regulating β-cell gene expression.

UI MeSH Term Description Entries
D007328 Insulin A 51-amino acid pancreatic hormone that plays a major role in the regulation of glucose metabolism, directly by suppressing endogenous glucose production (GLYCOGENOLYSIS; GLUCONEOGENESIS) and indirectly by suppressing GLUCAGON secretion and LIPOLYSIS. Native insulin is a globular protein comprised of a zinc-coordinated hexamer. Each insulin monomer containing two chains, A (21 residues) and B (30 residues), linked by two disulfide bonds. Insulin is used as a drug to control insulin-dependent diabetes mellitus (DIABETES MELLITUS, TYPE 1). Iletin,Insulin A Chain,Insulin B Chain,Insulin, Regular,Novolin,Sodium Insulin,Soluble Insulin,Chain, Insulin B,Insulin, Sodium,Insulin, Soluble,Regular Insulin
D002478 Cells, Cultured Cells propagated in vitro in special media conducive to their growth. Cultured cells are used to study developmental, morphologic, metabolic, physiologic, and genetic processes, among others. Cultured Cells,Cell, Cultured,Cultured Cell
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
D000078790 Insulin Secretion Production and release of insulin from PANCREATIC BETA CELLS that primarily occurs in response to elevated BLOOD GLUCOSE levels. Secretion, Insulin
D000818 Animals Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA. Animal,Metazoa,Animalia
D015398 Signal Transduction The intracellular transfer of information (biological activation/inhibition) through a signal pathway. In each signal transduction system, an activation/inhibition signal from a biologically active molecule (hormone, neurotransmitter) is mediated via the coupling of a receptor/enzyme to a second messenger system or to an ion channel. Signal transduction plays an important role in activating cellular functions, cell differentiation, and cell proliferation. Examples of signal transduction systems are the GAMMA-AMINOBUTYRIC ACID-postsynaptic receptor-calcium ion channel system, the receptor-mediated T-cell activation pathway, and the receptor-mediated activation of phospholipases. Those coupled to membrane depolarization or intracellular release of calcium include the receptor-mediated activation of cytotoxic functions in granulocytes and the synaptic potentiation of protein kinase activation. Some signal transduction pathways may be part of larger signal transduction pathways; for example, protein kinase activation is part of the platelet activation signal pathway. Cell Signaling,Receptor-Mediated Signal Transduction,Signal Pathways,Receptor Mediated Signal Transduction,Signal Transduction Pathways,Signal Transduction Systems,Pathway, Signal,Pathway, Signal Transduction,Pathways, Signal,Pathways, Signal Transduction,Receptor-Mediated Signal Transductions,Signal Pathway,Signal Transduction Pathway,Signal Transduction System,Signal Transduction, Receptor-Mediated,Signal Transductions,Signal Transductions, Receptor-Mediated,System, Signal Transduction,Systems, Signal Transduction,Transduction, Signal,Transductions, Signal
D015815 Cell Adhesion Molecules Surface ligands, usually glycoproteins, that mediate cell-to-cell adhesion. Their functions include the assembly and interconnection of various vertebrate systems, as well as maintenance of tissue integration, wound healing, morphogenic movements, cellular migrations, and metastasis. Cell Adhesion Molecule,Intercellular Adhesion Molecule,Intercellular Adhesion Molecules,Leukocyte Adhesion Molecule,Leukocyte Adhesion Molecules,Saccharide-Mediated Cell Adhesion Molecules,Saccharide Mediated Cell Adhesion Molecules,Adhesion Molecule, Cell,Adhesion Molecule, Intercellular,Adhesion Molecule, Leukocyte,Adhesion Molecules, Cell,Adhesion Molecules, Intercellular,Adhesion Molecules, Leukocyte,Molecule, Cell Adhesion,Molecule, Intercellular Adhesion,Molecule, Leukocyte Adhesion,Molecules, Cell Adhesion,Molecules, Intercellular Adhesion,Molecules, Leukocyte Adhesion
D048868 Adaptor Proteins, Signal Transducing A broad category of carrier proteins that play a role in SIGNAL TRANSDUCTION. They generally contain several modular domains, each of which having its own binding activity, and act by forming complexes with other intracellular-signaling molecules. Signal-transducing adaptor proteins lack enzyme activity, however their activity can be modulated by other signal-transducing enzymes Signal Transducing Adaptor Proteins
D050417 Insulin-Secreting Cells A type of pancreatic cell representing about 50-80% of the islet cells. Beta cells secrete INSULIN. Pancreatic beta Cells,beta Cells, Pancreatic,Pancreatic B Cells,B Cell, Pancreatic,B Cells, Pancreatic,Cell, Insulin-Secreting,Cells, Insulin-Secreting,Insulin Secreting Cells,Insulin-Secreting Cell,Pancreatic B Cell,Pancreatic beta Cell,beta Cell, Pancreatic
D051273 Glucose Transporter Type 2 A glucose transport facilitator that is expressed primarily in PANCREATIC BETA CELLS; LIVER; and KIDNEYS. It may function as a GLUCOSE sensor to regulate INSULIN release and glucose HOMEOSTASIS. GLUT-2 Protein,GLUT2 Protein,SLC2A2 Protein,Solute Carrier Family 2, Facilitated Glucose Transporter, Member 2 Protein,GLUT 2 Protein

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