Signal transducer and activator of transcription 5 activation is sufficient to drive transcriptional induction of cyclin D2 gene and proliferation of rat pancreatic beta-cells
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Signal transducer and activator of transcription 5 activation is sufficient to drive transcriptional induction of cyclin D2 gene and proliferation of rat pancreatic beta-cells. / Friedrichsen, Birgitte N; Richter, Henrijette E; Hansen, Johnny A; Rhodes, Christopher J; Nielsen, Jens Høiriis; Billestrup, Nils; Møldrup, Annette.
I: Molecular endocrinology (Baltimore, Md.), Bind 17, Nr. 5, 05.2003, s. 945-58.Publikation: Bidrag til tidsskrift › Tidsskriftartikel › Forskning › fagfællebedømt
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T1 - Signal transducer and activator of transcription 5 activation is sufficient to drive transcriptional induction of cyclin D2 gene and proliferation of rat pancreatic beta-cells
AU - Friedrichsen, Birgitte N
AU - Richter, Henrijette E
AU - Hansen, Johnny A
AU - Rhodes, Christopher J
AU - Nielsen, Jens Høiriis
AU - Billestrup, Nils
AU - Møldrup, Annette
PY - 2003/5
Y1 - 2003/5
N2 - Signal transducer and activator of transcription 5 (STAT5) activation plays a central role in GH- and prolactin-mediated signal transduction in the pancreatic beta-cells. In previous experiments we demonstrated that STAT5 activation is necessary for human (h)GH-stimulated proliferation of INS-1 cells and hGH-induced increase of mRNA-levels of the cell cycle regulator cyclin D2. In this study we have further characterized the role of STAT5 in the regulation of cyclin D expression and beta-cell proliferation by hGH. Cyclin D2 mRNA and protein levels (but not cyclin D1 and D3) were induced in a time-dependent manner by hGH in INS-1 cells. Inhibition of protein synthesis by coincubation with cycloheximide did not affect the hGH-induced increase of cyclin D2 mRNA levels at 4 h. Expression of a dominant negative STAT5 mutant, STAT5aDelta749, partially inhibited cyclin D2 protein levels. INS-1 cells transiently transfected with a cyclin D2 promoter-reporter construct revealed a 3- to 5-fold increase of transcriptional activity in response to hGH stimulation. Furthermore, coexpression of a constitutive active STAT5 mutant (either CA-STAT5a or CA-STAT5b) was sufficient to drive transactivation of the promoter. CA-STAT5b was stably expressed in INS-1 cells under the control of a doxycycline-inducible promoter. Gel retardation experiments using a probe representing a putative STAT5 binding site in the cyclin D2 promoter revealed binding of the doxycycline-induced CA-STAT5b. Furthermore, induction of CA-STAT5b stimulated transcriptional activation of the cyclin D2 promoter and induced hGH-independent proliferation in these cells. In primary beta-cells, adenovirus-mediated expression of CA-STAT5b profoundly stimulated DNA-synthesis (5.3-fold over control) in the absence of hGH. Our studies indicate that STAT5 activation is sufficient to drive proliferation of the beta-cells and that cyclin D2 may be a critical target gene for STAT5 in this process.
AB - Signal transducer and activator of transcription 5 (STAT5) activation plays a central role in GH- and prolactin-mediated signal transduction in the pancreatic beta-cells. In previous experiments we demonstrated that STAT5 activation is necessary for human (h)GH-stimulated proliferation of INS-1 cells and hGH-induced increase of mRNA-levels of the cell cycle regulator cyclin D2. In this study we have further characterized the role of STAT5 in the regulation of cyclin D expression and beta-cell proliferation by hGH. Cyclin D2 mRNA and protein levels (but not cyclin D1 and D3) were induced in a time-dependent manner by hGH in INS-1 cells. Inhibition of protein synthesis by coincubation with cycloheximide did not affect the hGH-induced increase of cyclin D2 mRNA levels at 4 h. Expression of a dominant negative STAT5 mutant, STAT5aDelta749, partially inhibited cyclin D2 protein levels. INS-1 cells transiently transfected with a cyclin D2 promoter-reporter construct revealed a 3- to 5-fold increase of transcriptional activity in response to hGH stimulation. Furthermore, coexpression of a constitutive active STAT5 mutant (either CA-STAT5a or CA-STAT5b) was sufficient to drive transactivation of the promoter. CA-STAT5b was stably expressed in INS-1 cells under the control of a doxycycline-inducible promoter. Gel retardation experiments using a probe representing a putative STAT5 binding site in the cyclin D2 promoter revealed binding of the doxycycline-induced CA-STAT5b. Furthermore, induction of CA-STAT5b stimulated transcriptional activation of the cyclin D2 promoter and induced hGH-independent proliferation in these cells. In primary beta-cells, adenovirus-mediated expression of CA-STAT5b profoundly stimulated DNA-synthesis (5.3-fold over control) in the absence of hGH. Our studies indicate that STAT5 activation is sufficient to drive proliferation of the beta-cells and that cyclin D2 may be a critical target gene for STAT5 in this process.
KW - Animals
KW - Binding Sites
KW - Cell Division
KW - Cells, Cultured
KW - Cyclin D2
KW - Cyclins
KW - DNA-Binding Proteins
KW - Doxycycline
KW - Gene Expression Regulation
KW - Human Growth Hormone
KW - Islets of Langerhans
KW - Mice
KW - Milk Proteins
KW - Mutation
KW - Promoter Regions, Genetic
KW - Rats
KW - STAT5 Transcription Factor
KW - Trans-Activators
KW - Transcription, Genetic
KW - Transcriptional Activation
U2 - 10.1210/me.2002-0356
DO - 10.1210/me.2002-0356
M3 - Journal article
C2 - 12586844
VL - 17
SP - 945
EP - 958
JO - Molecular Endocrinology
JF - Molecular Endocrinology
SN - 0888-8809
IS - 5
ER -
ID: 47972341