TY - JOUR

T1 - The effect of suppressor of cytokine signaling 3 on GH signaling in beta-cells

AU - Rønn, Sif G

AU - Hansen, Johnny A

AU - Lindberg, Karen

AU - Karlsen, Allan E

AU - Billestrup, Nils

PY - 2002/9

Y1 - 2002/9

N2 - GH is an important regulator of cell growth and metabolism. In the pancreas, GH stimulates mitogenesis as well as insulin production in beta-cells. The cellular effects of GH are exerted mainly through activation of the Janus kinase-signal transducer and activator of transcription (STAT) pathway. Recently it has been found that suppressors of cytokine signaling (SOCS) proteins are able to inhibit GH-induced signal transduction. In the present study, the role of SOCS-3 in GH signaling was investigated in the pancreatic beta-cell lines RIN-5AH and INS-1 by means of inducible expression systems. Via stable transfection of the beta-cell lines with plasmids expressing SOCS-3 under the control of an inducible promoter, a time- and dose-dependent expression of SOCS-3 in the cells was obtained. EMSA showed that SOCS-3 is able to inhibit GH-induced DNA binding of both STAT3 and STAT5 in RIN-5AH cells. Furthermore, using Northern blot analysis it was shown that SOCS-3 can completely inhibit GH-induced insulin production in these cells. Finally, 5-bromodeoxyuridine incorporation followed by fluorescence-activated cell sorting analysis showed that SOCS-3 inhibits GH-induced proliferation of INS-1 cells. These findings support the hypothesis that SOCS-3 is a major regulator of GH signaling in insulin-producing cells.

AB - GH is an important regulator of cell growth and metabolism. In the pancreas, GH stimulates mitogenesis as well as insulin production in beta-cells. The cellular effects of GH are exerted mainly through activation of the Janus kinase-signal transducer and activator of transcription (STAT) pathway. Recently it has been found that suppressors of cytokine signaling (SOCS) proteins are able to inhibit GH-induced signal transduction. In the present study, the role of SOCS-3 in GH signaling was investigated in the pancreatic beta-cell lines RIN-5AH and INS-1 by means of inducible expression systems. Via stable transfection of the beta-cell lines with plasmids expressing SOCS-3 under the control of an inducible promoter, a time- and dose-dependent expression of SOCS-3 in the cells was obtained. EMSA showed that SOCS-3 is able to inhibit GH-induced DNA binding of both STAT3 and STAT5 in RIN-5AH cells. Furthermore, using Northern blot analysis it was shown that SOCS-3 can completely inhibit GH-induced insulin production in these cells. Finally, 5-bromodeoxyuridine incorporation followed by fluorescence-activated cell sorting analysis showed that SOCS-3 inhibits GH-induced proliferation of INS-1 cells. These findings support the hypothesis that SOCS-3 is a major regulator of GH signaling in insulin-producing cells.

KW - Cell Division

KW - Cells, Cultured

KW - DNA-Binding Proteins

KW - Electrophoretic Mobility Shift Assay

KW - Flow Cytometry

KW - Growth Hormone

KW - Humans

KW - Insulin

KW - Islets of Langerhans

KW - Milk Proteins

KW - Proteins

KW - RNA, Messenger

KW - Repressor Proteins

KW - STAT3 Transcription Factor

KW - STAT5 Transcription Factor

KW - Signal Transduction

KW - Suppressor of Cytokine Signaling Proteins

KW - Trans-Activators

KW - Transcription Factors

U2 - 10.1210/me.2002-0082

DO - 10.1210/me.2002-0082

M3 - Journal article

C2 - 12198248

VL - 16

SP - 2124

EP - 2134

JO - Molecular Endocrinology

JF - Molecular Endocrinology

SN - 0888-8809

IS - 9

ER -