Glucose Stimulates Translocation of the Homeodomain Transcription Factor PDX1 from the Cytoplasm to the Nucleus in Pancreatic β-Cells

Abstract

One of the mechanisms whereby glucose stimulates insulin gene transcription in pancreatic β-cells involves activation of the homeodomain transcription factor PDX1 (pancreatic/duodenal homeobox-1) via a stress-activated pathway involving stress-activated protein kinase 2 (SAPK2, also termed RK/p38, CSBP, and Mxi2). In the present study we show, by Western blotting and electrophoretic mobility shift assay, that in human islets of Langerhans incubated in low glucose (3 mm) PDX1 exists as an inactive 31-kDa protein localized exclusively in the cytoplasm. Transfer of the islets to high (16 mm) glucose results in rapid (within 10 min) conversion of PDX1 to an active 46-kDa form that was present predominantly in the nucleus. Activation of PDX1 appears to involve phosphorylation, as shown by incorporation of32Pi into the 46-kDa form of the protein. These effects of glucose could be mimicked by chemical stress (sodium arsenite), or by overexpression of SAPK2 in the β-cell line MIN6. Overexpression of SAPK2 also stimulated PDX1-dependent transcription of a –50 to –250 region of the human insulin gene promoter linked to a firefly luciferase reporter gene. The effects of glucose were inhibited by the SAPK2 inhibitor SB 203580, and by wortmannin and LY 294002, which inhibit phosphatidylinositol 3-kinase, although the effects of stress (arsenite) were inhibited only by SB 203580. These results demonstrate that glucose regulates the insulin gene promoter through activation and nuclear translocation of PDX1 via the SAPK2 pathway. One of the mechanisms whereby glucose stimulates insulin gene transcription in pancreatic β-cells involves activation of the homeodomain transcription factor PDX1 (pancreatic/duodenal homeobox-1) via a stress-activated pathway involving stress-activated protein kinase 2 (SAPK2, also termed RK/p38, CSBP, and Mxi2). In the present study we show, by Western blotting and electrophoretic mobility shift assay, that in human islets of Langerhans incubated in low glucose (3 mm) PDX1 exists as an inactive 31-kDa protein localized exclusively in the cytoplasm. Transfer of the islets to high (16 mm) glucose results in rapid (within 10 min) conversion of PDX1 to an active 46-kDa form that was present predominantly in the nucleus. Activation of PDX1 appears to involve phosphorylation, as shown by incorporation of32Pi into the 46-kDa form of the protein. These effects of glucose could be mimicked by chemical stress (sodium arsenite), or by overexpression of SAPK2 in the β-cell line MIN6. Overexpression of SAPK2 also stimulated PDX1-dependent transcription of a –50 to –250 region of the human insulin gene promoter linked to a firefly luciferase reporter gene. The effects of glucose were inhibited by the SAPK2 inhibitor SB 203580, and by wortmannin and LY 294002, which inhibit phosphatidylinositol 3-kinase, although the effects of stress (arsenite) were inhibited only by SB 203580. These results demonstrate that glucose regulates the insulin gene promoter through activation and nuclear translocation of PDX1 via the SAPK2 pathway. The homeodomain transcription factor PDX1 (pancreatic/duodenal homeobox-1), which has previously been called IPF1 (1Ohlsson H. Karlsson K. Edlund T. EMBO J. 1993; 12: 4251-4259Crossref PubMed Scopus (765) Google Scholar), IDX1 (2Miller C.P. McGehee Jr., R.E. Habener J.F. EMBO J. 1993; 13: 1145-1156Crossref Scopus (376) Google Scholar), STF1 (3Leonard J. Peers B. Johnson T. Ferreri S.L. Montminy M.R. Mol. Endocrinol. 1993; 7: 1275-1283Crossref PubMed Google Scholar), or IUF1 (4Boam D.W.S. Docherty K. Biochem. J. 1989; 264: 233-239Crossref PubMed Scopus (66) Google Scholar), plays an important role in lineage determination in the developing endocrine pancreas (5Jonsson J. Carlsson L. Edlund T. Edlund H. Nature. 1994; 371: 606-609Crossref PubMed Scopus (1552) Google Scholar, 6Guz Y. Montminy M.R. Stein R. Leonard J. Gamer L.W. Wright C.V.E. Teitelman G. Development. 1995; 121: 11-18Crossref PubMed Google Scholar). PDX1 binds to four sites (A1, A2, A3, and A5) with the consensus sequence C(C/T)TAATG in the human insulin promoter (7Clark A.R. Petersen H. Read M.L. Scott V. Michelsen B. Docherty K. FEBS Lett. 1993; 329: 139-143Crossref PubMed Scopus (17) Google Scholar). Although it can transactivate the insulin promoter (8Petersen H.V. Serup P. Leonard J. Michelsen 1994; PubMed Scopus Google Scholar, Leonard J. Teitelman G. Montminy M.R. Mol. Endocrinol. 1995; Scholar, P. J. PubMed Scopus Google Scholar), role in insulin transcription insulin gene transcription can in the of PDX1 H. Docherty Read M.L. Docherty K. FEBS Lett. PubMed Scopus Google Scholar, Y. H. T. H. Y. Y. J. PubMed Scopus Google Scholar). a role PDX1 in the mechanisms whereby glucose stimulates insulin gene transcription in to in glucose Y. 1993; PubMed Scopus Google Scholar, Read M.L. Docherty K. Biochem. J. 1994; PubMed Scopus Google Scholar, H. PubMed Scopus Google Scholar). glucose has been shown to PDX1 and insulin promoter in β-cells via a stress-activated pathway involving stress-activated protein kinase 2 (SAPK2, also termed RK/p38, CSBP, and P. Docherty K. J. PubMed Scopus Google a of an of protein that in to as and by that of stress P. 7: PubMed Scopus Google Scholar). In pancreatic glucose stimulates the SAPK2 pathway by a that involves phosphatidylinositol 3-kinase, phosphatidylinositol electrophoretic mobility shift nuclear 3-kinase, phosphatidylinositol electrophoretic mobility shift nuclear stress stimulates the SAPK2 pathway in and by a of P. Docherty K. J. PubMed Scopus Google in has a of to that as it to sequence in the insulin promoter as by electrophoretic mobility shift of PDX1 with SAPK2 in the of and a β-cell with a shift in to P. Docherty K. J. PubMed Scopus Google Scholar). The shift in as In the present study we that PDX1 exists as the inactive 31-kDa form in the of human islets incubated in low (3 mm) with glucose stimulates conversion to the active 46-kDa which localized predominantly in the nucleus. These inhibited by SB inhibitor of and LY of and mimicked by and overexpression of were to the of glucose the and of islets of Langerhans were incubated in to and PDX1 by Western blotting of In glucose PDX1 was present as a 31-kDa protein 10 in the 31-kDa protein was to the 46-kDa was the of glucose the of the of human islets were incubated in or glucose and and nuclear In the 31-kDa form was present in the in the 46-kDa form was present in the and the with the 46-kDa form to the 31-kDa In the of the 46-kDa that conversion to the 31-kDa form was with of the 46-kDa The 31-kDa form was inactive as by the 46-kDa form present in the and the was active of the in as PDX1 was by and role of in the activation of PDX1 was by of with and of high glucose was into the 46-kDa form of PDX1 low glucose incorporation was and Western of the 2 that of the protein were was only into the 46-kDa form of the which was high glucose the of the of the β-cell nuclear and were by Western blotting a binds to the of the human insulin gene promoter and has a of 2 the of in the nuclear of glucose glucose incorporation of32Pi into the 46-kDa form of of PDX1 nuclear and incubated in with were incubated in glucose or glucose and to the of PDX1 in and Western of in a Western of the and nuclear incubated in glucose or incubated in glucose by in glucose a has a of SAPK2 and previously been in the of PDX1 the of in the translocation of PDX1 to the was that conversion of PDX1 the 31-kDa to the 46-kDa form and translocation of the 46-kDa form into the was inhibited by the SAPK2 inhibitor SB 203580, and by the wortmannin and LY SAPK2 a stress-activated protein the of which can be stimulated by with the The effects of glucose PDX1 and were mimicked by a role SAPK2 in shown previously P. Docherty K. J. PubMed Scopus Google the effects of were inhibited by SB by wortmannin and LY The SB glucose and effects was glucose and chemical stress of Western of and nuclear human islets of Langerhans incubated in glucose and or glucose by glucose or in glucose in the of the SB LY and wortmannin were to Western of and nuclear human islets of Langerhans incubated in glucose and or in glucose by in the of the and wortmannin were to the of were with a Overexpression was by the of a protein in that was in In with PDX1 was present as the 31-kDa form in the cytoplasm. with PDX1 was to the 46-kDa which was present in the and nucleus. with SAPK2 were incubated in PDX1 was present as the 46-kDa form in the and in the that overexpression of SAPK2 in conversion of PDX1 to the 46-kDa form that was localized predominantly in the nucleus. Overexpression of SAPK2 also PDX1 in low The and activation of PDX1 to in the as Western of nuclear and SAPK2 that the SAPK2 protein localized in the and in the β-cell of SAPK2 the of high glucose Western of and with a SAPK2 has an of Western of or nuclear or SAPK2 were incubated in or glucose by as electrophoretic mobility shift of nuclear incubated in glucose by glucose or SAPK2 which were incubated in glucose was the of the human insulin gene promoter as of SAPK2 the of high glucose reporter gene Western of and nuclear a SAPK2 has an of were with the or with and were incubated in or glucose or in the of SB In and were with SAPK2 as shown previously P. Docherty K. J. PubMed Scopus Google Scholar), glucose stimulates the of a the firefly luciferase gene the of the kinase which by a human insulin gene to Overexpression of SAPK2 in the which the insulin gene a of to that with glucose The of overexpression of SAPK2 the was inhibited by SB that effects were the of the SAPK2 in the previously shown that glucose PDX1 and insulin promoter in pancreatic β-cells via a pathway involving SAPK2 also that SAPK2 in PDX1 with a in the of PDX1 to P. Docherty K. J. PubMed Scopus Google Scholar). In the present we that glucose stimulates the conversion of PDX1 a 31-kDa to a 46-kDa form in human islets of Langerhans and in The activation of and translocation to the were inhibited by SB and stimulated by and overexpression of a role SAPK2 in glucose stimulates a rapid translocation of PDX1 to the with the results of a study that glucose stimulates translocation of a PDX1 the nuclear to the J. PubMed Scopus Google of PDX1 appears to the in translocation to the and activation of it the in that or a which to be a in PDX1 that mobility in the in could a transcription nuclear as nuclear and the nuclear R. J. 1995; Scholar), and R. T. L. PubMed Scopus Google Scholar, G. J. PubMed Scopus Google Scholar), which through the of protein as In the of G. J. PubMed Scopus Google Scholar), the of which the of the protein by and translocation the to the nucleus. be with of transcription through can by transcription in the into the T. 1995; PubMed Scopus Google Scholar). the insulin stimulates the nuclear translocation of as protein kinase R. J. Mol. 12: PubMed Google Scholar), which can nuclear protein or H. P. Biochem. J. PubMed Scopus Google Scholar). In the present study SAPK2 shown to be present exclusively in the that the PDX1 activation exclusively in the translocation of an active PDX1 into the activation of PDX1 nuclear translocation through a β-cell pathway involving 3-kinase, and in the activation of overexpression of SAPK2 can PDX1 translocation to the in glucose In overexpression of SAPK2 stimulated PDX1 to in high glucose of PDX1 by overexpression of SAPK2 in or and to activation of PDX1 In β-cells SAPK2 a in PDX1 with glucose a Overexpression of SAPK2 to high in a of the PDX1 activation in an to and PDX1 protein. of PDX1 to be in the of insulin gene transcription to in high as PDX1 transcription of the insulin gene. and transcription of the insulin gene. PDX1 only an in the of and a stimulates PDX1 and nuclear translocation through PDX1 in which also binds to the human insulin gene promoter H. PubMed Scopus Google Scholar, P. Docherty K. J. PubMed Scopus Google Scholar), has through in in shown that transcription by with SAPK2 J. Biochem. J. PubMed Scopus Google Scholar), which in through of a kinase as Y. J. P. EMBO J. PubMed Scopus Google Scholar). SAPK2 has been shown to transcription and P. 7: PubMed Scopus Google Scholar). protein also been in the nuclear of transcription In activation of kinase and of stress-activated protein translocation of transcription and to the in the of Y. J. P. EMBO J. PubMed Scopus Google Scholar). The nuclear translocation of by an of T. 1995; PubMed Scopus Google Scholar), stress has been that glucose insulin and insulin promoter in via of insulin to of the β-cell insulin B. T. Mol. PubMed Scopus Google Scholar). The insulin effects were through 3-kinase, and kinase also that insulin stimulates PDX1 in human islets of Langerhans and the human insulin promoter in and K. in study the effects of insulin were inhibited by the wortmannin and LY and by the SAPK2 inhibitor SB by the kinase inhibitor that of insulin by insulin involve to the activation of glucose stimulates translocation of the homeodomain transcription factor PDX1 the to the in pancreatic β-cells via a pathway involving translocation with a in insulin promoter and a in the of insulin The homeodomain transcription factor PDX1 (pancreatic/duodenal homeobox-1), which has previously been called IPF1 (1Ohlsson H. Karlsson K. Edlund T. EMBO J. 1993; 12: 4251-4259Crossref PubMed Scopus (765) Google Scholar), IDX1 (2Miller C.P. McGehee Jr., R.E. Habener J.F. EMBO J. 1993; 13: 1145-1156Crossref Scopus (376) Google Scholar), STF1 (3Leonard J. Peers B. Johnson T. Ferreri S.L. Montminy M.R. Mol. Endocrinol. 1993; 7: 1275-1283Crossref PubMed Google Scholar), or IUF1 (4Boam D.W.S. Docherty K. Biochem. J. 1989; 264: 233-239Crossref PubMed Scopus (66) Google Scholar), plays an important role in lineage determination in the developing endocrine pancreas (5Jonsson J. Carlsson L. Edlund T. Edlund H. Nature. 1994; 371: 606-609Crossref PubMed Scopus (1552) Google Scholar, 6Guz Y. Montminy M.R. Stein R. Leonard J. Gamer L.W. Wright C.V.E. Teitelman G. Development. 1995; 121: 11-18Crossref PubMed Google Scholar). PDX1 binds to four sites (A1, A2, A3, and A5) with the consensus sequence C(C/T)TAATG in the human insulin promoter (7Clark A.R. Petersen H. Read M.L. Scott V. Michelsen B. Docherty K. FEBS Lett. 1993; 329: 139-143Crossref PubMed Scopus (17) Google Scholar). Although it can transactivate the insulin promoter (8Petersen H.V. Serup P. Leonard J. Michelsen 1994; PubMed Scopus Google Scholar, Leonard J. Teitelman G. Montminy M.R. Mol. Endocrinol. 1995; Scholar, P. J. PubMed Scopus Google Scholar), role in insulin transcription insulin gene transcription can in the of PDX1 H. Docherty Read M.L. Docherty K. FEBS Lett. PubMed Scopus Google Scholar, Y. H. T. H. Y. Y. J. PubMed Scopus Google Scholar). a role PDX1 in the mechanisms whereby glucose stimulates insulin gene transcription in to in glucose Y. 1993; PubMed Scopus Google Scholar, Read M.L. Docherty K. Biochem. J. 1994; PubMed Scopus Google Scholar, H. PubMed Scopus Google Scholar). glucose has been shown to PDX1 and insulin promoter in β-cells via a stress-activated pathway involving stress-activated protein kinase 2 (SAPK2, also termed RK/p38, CSBP, and P. Docherty K. J. PubMed Scopus Google Scholar). SAPK2 a of an of protein that in to as and by that of stress P. 7: PubMed Scopus Google Scholar). In pancreatic glucose stimulates the SAPK2 pathway by a that involves phosphatidylinositol 3-kinase, phosphatidylinositol electrophoretic mobility shift nuclear 3-kinase, phosphatidylinositol electrophoretic mobility shift nuclear stress stimulates the SAPK2 pathway in and by a of P. Docherty K. J. PubMed Scopus Google Scholar). in has a of to that as it to sequence in the insulin promoter as by electrophoretic mobility shift of PDX1 with SAPK2 in the of and a β-cell with a shift in to P. Docherty K. J. PubMed Scopus Google Scholar). The shift in as In the present study we that PDX1 exists as the inactive 31-kDa form in the of human islets incubated in low (3 mm) with glucose stimulates conversion to the active 46-kDa which localized predominantly in the nucleus. These inhibited by SB inhibitor of and LY of and mimicked by and overexpression of were to the of glucose the and of islets of Langerhans were incubated in to and PDX1 by Western blotting of In glucose PDX1 was present as a 31-kDa protein 10 in the 31-kDa protein was to the 46-kDa was the of glucose the of the of human islets were incubated in or glucose and and nuclear In the 31-kDa form was present in the in the 46-kDa form was present in the and the with the 46-kDa form to the 31-kDa In the of the 46-kDa that conversion to the 31-kDa form was with of the 46-kDa The 31-kDa form was inactive as by the 46-kDa form present in the and the was active of the in as PDX1 was by and role of in the activation of PDX1 was by of with and of high glucose was into the 46-kDa form of PDX1 low glucose incorporation was and Western of the 2 that of the protein were was only into the 46-kDa form of the which was high glucose the of the of the β-cell nuclear and were by Western blotting a binds to the of the human insulin gene promoter and has a of 2 the of in the nuclear of glucose SAPK2 and previously been in the of PDX1 the of in the translocation of PDX1 to the was that conversion of PDX1 the 31-kDa to the 46-kDa form and translocation of the 46-kDa form into the was inhibited by the SAPK2 inhibitor SB 203580, and by the wortmannin and LY SAPK2 a stress-activated protein the of which can be stimulated by with the The effects of glucose PDX1 and were mimicked by a role SAPK2 in shown previously P. Docherty K. J. PubMed Scopus Google the effects of were inhibited by SB by wortmannin and LY The SB glucose and effects was glucose and chemical stress of Western of and nuclear human islets of Langerhans incubated in glucose and or glucose by glucose or in glucose in the of the SB LY and wortmannin were to Western of and nuclear human islets of Langerhans incubated in glucose and or in glucose by in the of the and wortmannin were to the of were with a Overexpression was by the of a protein in that was in In with PDX1 was present as the 31-kDa form in the cytoplasm. with PDX1 was to the 46-kDa which was present in the and nucleus. with SAPK2 were incubated in PDX1 was present as the 46-kDa form in the and in the that overexpression of SAPK2 in conversion of PDX1 to the 46-kDa form that was localized predominantly in the nucleus. Overexpression of SAPK2 also PDX1 in low The and activation of PDX1 to in the as Western of nuclear and SAPK2 that the SAPK2 protein localized in the and in the β-cell of SAPK2 the of high glucose Western of and with a SAPK2 has an of Western of or nuclear or SAPK2 were incubated in or glucose by as electrophoretic mobility shift of nuclear incubated in glucose by glucose or SAPK2 which were incubated in glucose was the of the human insulin gene promoter as of SAPK2 the of high glucose reporter gene Western of and nuclear a SAPK2 has an of were with the or with and were incubated in or glucose or in the of SB In and were with SAPK2 as shown previously P. Docherty K. J. PubMed Scopus Google Scholar), glucose stimulates the of a the firefly luciferase gene the of the kinase which by a human insulin gene to Overexpression of SAPK2 in the which the insulin gene a of to that with glucose The of overexpression of SAPK2 the was inhibited by SB that effects were the of the SAPK2 in the were to the of glucose the and of islets of Langerhans were incubated in to and PDX1 by Western blotting of In glucose PDX1 was present as a 31-kDa protein 10 in the 31-kDa protein was to the 46-kDa was the of glucose the of the of human islets were incubated in or glucose and and nuclear In the 31-kDa form was present in the in the 46-kDa form was present in the and the with the 46-kDa form to the 31-kDa In the of the 46-kDa that conversion to the 31-kDa form was with of the 46-kDa The 31-kDa form was inactive as by the 46-kDa form present in the and the was active of the in as PDX1 was by and The role of in the activation of PDX1 was by of with and of high glucose was into the 46-kDa form of PDX1 low glucose incorporation was and Western of the 2 that of the protein were was only into the 46-kDa form of the which was high glucose the of the of the β-cell nuclear and were by Western blotting a binds to the of the human insulin gene promoter and has a of 2 the of in the nuclear of glucose SAPK2 and previously been in the of PDX1 the of in the translocation of PDX1 to the was that conversion of PDX1 the 31-kDa to the 46-kDa form and translocation of the 46-kDa form into the was inhibited by the SAPK2 inhibitor SB 203580, and by the wortmannin and LY SAPK2 a stress-activated protein the of which can be stimulated by with the The effects of glucose PDX1 and were mimicked by a role SAPK2 in shown previously P. Docherty K. J. PubMed Scopus Google the effects of were inhibited by SB by wortmannin and LY The SB glucose and effects was the of were with a Overexpression was by the of a protein in that was in In with PDX1 was present as the 31-kDa form in the cytoplasm. with PDX1 was to the 46-kDa which was present in the and nucleus. with SAPK2 were incubated in PDX1 was present as the 46-kDa form in the and in the that overexpression of SAPK2 in conversion of PDX1 to the 46-kDa form that was localized predominantly in the nucleus. Overexpression of SAPK2 also PDX1 in low The and activation of PDX1 to in the as Western of nuclear and SAPK2 that the SAPK2 protein localized in the and in the β-cell shown previously P. Docherty K. J. PubMed Scopus Google Scholar), glucose stimulates the of a the firefly luciferase gene the of the kinase which by a human insulin gene to Overexpression of SAPK2 in the which the insulin gene a of to that with glucose The of overexpression of SAPK2 the was inhibited by SB that effects were the of the SAPK2 in the previously shown that glucose PDX1 and insulin promoter in pancreatic β-cells via a pathway involving SAPK2 also that SAPK2 in PDX1 with a in the of PDX1 to P. Docherty K. J. PubMed Scopus Google Scholar). In the present we that glucose stimulates the conversion of PDX1 a 31-kDa to a 46-kDa form in human islets of Langerhans and in The activation of and translocation to the were inhibited by SB and stimulated by and overexpression of a role SAPK2 in glucose stimulates a rapid translocation of PDX1 to the with the results of a study that glucose stimulates translocation of a PDX1 the nuclear to the J. PubMed Scopus Google of PDX1 appears to the in translocation to the and activation of it the in that or a which to be a in PDX1 that mobility in the in could a transcription nuclear as nuclear and the nuclear R. J. 1995; Scholar), and R. T. L. PubMed Scopus Google Scholar, G. J. PubMed Scopus Google Scholar), which through the of protein as In the of G. J. PubMed Scopus Google Scholar), the of which the of the protein by and translocation the to the nucleus. be with of transcription through can by transcription in the into the T. 1995; PubMed Scopus Google Scholar). the insulin stimulates the nuclear translocation of as protein kinase R. J. Mol. 12: PubMed Google Scholar), which can nuclear protein or H. P. Biochem. J. PubMed Scopus Google Scholar). In the present study SAPK2 shown to be present exclusively in the that the PDX1 activation exclusively in the translocation of an active PDX1 into the activation of PDX1 nuclear translocation through a β-cell pathway involving 3-kinase, and in the activation of overexpression of SAPK2 can PDX1 translocation to the in glucose In overexpression of SAPK2 stimulated PDX1 to in high glucose of PDX1 by overexpression of SAPK2 in or and to activation of PDX1 In β-cells SAPK2 a in PDX1 with glucose a Overexpression of SAPK2 to high in a of the PDX1 activation in an to and PDX1 protein. of PDX1 to be in the of insulin gene transcription to in high as PDX1 transcription of the insulin gene. and transcription of the insulin gene. PDX1 only an in the of and a stimulates PDX1 and nuclear translocation through PDX1 in which also binds to the human insulin gene promoter H. PubMed Scopus Google Scholar, P. Docherty K. J. PubMed Scopus Google Scholar), has through in in shown that transcription by with SAPK2 J. Biochem. J. PubMed Scopus Google Scholar), which in through of a kinase as Y. J. P. EMBO J. PubMed Scopus Google Scholar). SAPK2 has been shown to transcription and P. 7: PubMed Scopus Google Scholar). protein also been in the nuclear of transcription In activation of kinase and of stress-activated protein translocation of transcription and to the in the of Y. J. P. EMBO J. PubMed Scopus Google Scholar). The nuclear translocation of by an of T. 1995; PubMed Scopus Google Scholar), stress has been that glucose insulin and insulin promoter in via of insulin to of the β-cell insulin B. T. Mol. PubMed Scopus Google Scholar). The insulin effects were through 3-kinase, and kinase also that insulin stimulates PDX1 in human islets of Langerhans and the human insulin promoter in and K. in study the effects of insulin were inhibited by the wortmannin and LY and by the SAPK2 inhibitor SB by the kinase inhibitor that of insulin by insulin involve to the activation of glucose stimulates translocation of the homeodomain transcription factor PDX1 the to the in pancreatic β-cells via a pathway involving translocation with a in insulin promoter and a in the of insulin previously shown that glucose PDX1 and insulin promoter in pancreatic β-cells via a pathway involving SAPK2 also that SAPK2 in PDX1 with a in the of PDX1 to P. Docherty K. J. PubMed Scopus Google Scholar). In the present we that glucose stimulates the conversion of PDX1 a 31-kDa to a 46-kDa form in human islets of Langerhans and in The activation of and translocation to the were inhibited by SB and stimulated by and overexpression of a role SAPK2 in glucose stimulates a rapid translocation of PDX1 to the with the results of a study that glucose stimulates translocation of a PDX1 the nuclear to the J. PubMed Scopus Google Scholar). of PDX1 appears to the in translocation to the and activation of it the in that or a which to be a in PDX1 that mobility in the in could a transcription nuclear as nuclear and the nuclear R. J. 1995; Scholar), and R. T. L. PubMed Scopus Google Scholar, G. J. PubMed Scopus Google Scholar), which through the of protein as In the of G. J. PubMed Scopus Google Scholar), the of which the of the protein by and translocation the to the nucleus. be with of transcription through can by transcription in the into the T. 1995; PubMed Scopus Google Scholar). the insulin stimulates the nuclear translocation of as protein kinase R. J. Mol. 12: PubMed Google Scholar), which can nuclear protein or H. P. Biochem. J. PubMed Scopus Google Scholar). In the present study SAPK2 shown to be present exclusively in the that the PDX1 activation exclusively in the translocation of an active PDX1 into the nucleus. activation of PDX1 nuclear translocation through a β-cell pathway involving 3-kinase, and in the activation of overexpression of SAPK2 can PDX1 translocation to the in glucose In overexpression of SAPK2 stimulated PDX1 to in high glucose of PDX1 by overexpression of SAPK2 in or and to activation of PDX1 In β-cells SAPK2 a in PDX1 with glucose a Overexpression of SAPK2 to high in a of the PDX1 activation in an to and PDX1 protein. of PDX1 to be in the of insulin gene transcription to in high as PDX1 transcription of the insulin gene. and transcription of the insulin gene. PDX1 only an in the of and a stimulates PDX1 and nuclear translocation through PDX1 in which also binds to the human insulin gene promoter H. PubMed Scopus Google Scholar, P. Docherty K. J. PubMed Scopus Google Scholar), has through in in shown that transcription by with SAPK2 J. Biochem. J. PubMed Scopus Google Scholar), which in through of a kinase as Y. J. P. EMBO J. PubMed Scopus Google Scholar). SAPK2 has been shown to transcription and P. 7: PubMed Scopus Google Scholar). protein also been in the nuclear of transcription In activation of kinase and of stress-activated protein translocation of transcription and to the in the of Y. J. P. EMBO J. PubMed Scopus Google Scholar). The nuclear translocation of by an of T. 1995; PubMed Scopus Google Scholar), stress has been that glucose insulin and insulin promoter in via of insulin to of the β-cell insulin B. T. Mol. PubMed Scopus Google Scholar). The insulin effects were through 3-kinase, and kinase also that insulin stimulates PDX1 in human islets of Langerhans and the human insulin promoter in and K. in study the effects of insulin were inhibited by the wortmannin and LY and by the SAPK2 inhibitor SB by the kinase inhibitor that of insulin by insulin involve to the activation of In glucose stimulates translocation of the homeodomain transcription factor PDX1 the to the in pancreatic β-cells via a pathway involving translocation with a in insulin promoter and a in the of insulin P. and of