Parnaud Géraldine, Hammar Eva, Ribaux Pascale, Donath Marc Y, Berney Thierry, Halban Philippe A
Department of Genetic Medicine and Development, University of Geneva University Medical Center, Geneva, Switzerland. geraldine.parnaud@.unige.ch
Mol Endocrinol. 2009 Aug;23(8):1264-71. doi: 10.1210/me.2009-0008. Epub 2009 May 14.
Laminin-5-rich extracellular matrix derived from 804G cells (804G-ECM) induces spreading, improves glucose-stimulated insulin secretion, and increases survival and proliferation of rat pancreatic beta-cells. The aim of the study was to determine growth signaling pathways activated by ECM with a particular focus on Ca(2+)-dependent transcription factors. 804G-ECM increased rat beta-cell proliferation, and this stimulation was glucose and Ca(2+) dependent. NF-kappaB nuclear translocation as well as IkappaBalpha gene expression were also Ca(2+) dependent. Inhibition of NF-kappaB almost completely blocked 804G-ECM-stimulated beta-cell proliferation as did the soluble IL-1 receptor antagonist IL-1Ra. 804G-ECM-induced proliferation was also blocked by cyclosporin A and the VIVIT peptide, suggesting involvement of nuclear factor of activated T cells (NFAT)/calcineurin. Use of selective inhibitors further implicated other pathways in this process. Inhibition of phosphatidylinositol 3-kinase and protein kinase A both prevented beta-cell replication stimulated by 804G-ECM. Conversely, inhibition of MAPK, c-Jun N-terminal kinase, p38, and glycogen synthase kinase-3beta increased beta-cell proliferation on 804G-ECM. Our results suggest that Ca(2+) entry, which is necessary for increased beta-cell proliferation on 804G-ECM, is also involved in 804G-ECM-induced NF-kappaB activity. It is proposed that increased cytosolic Ca(2+) leads to activation of the transcription factors NFAT and NF-kappaB that in turn increase beta-cell proliferation. Activation of phosphatidylinositol 3-kinase by 804G-ECM also increases proliferation possibly by synergistic coactivation of NFAT via inhibition of glycogen synthase kinase-3beta, whereas IL-1beta may amplify the process by feed-forward activation of NF-kappaB. Conversely, inhibition of the MAPK pathway increased beta-cell proliferation, indicating a counterregulatory restraining role for this signaling pathway.
源自804G细胞的富含层粘连蛋白-5的细胞外基质（804G-ECM）可诱导大鼠胰岛β细胞铺展，改善葡萄糖刺激的胰岛素分泌，并提高其存活和增殖能力。本研究的目的是确定由细胞外基质激活的生长信号通路，特别关注钙（Ca2+）依赖性转录因子。804G-ECM可增加大鼠β细胞增殖，且这种刺激依赖于葡萄糖和Ca2+。核因子κB（NF-κB）的核转位以及IκBα基因表达也依赖于Ca2+。抑制NF-κB以及可溶性白细胞介素-1受体拮抗剂IL-1Ra几乎完全阻断了804G-ECM刺激的β细胞增殖。环孢素A和VIVIT肽也阻断了804G-ECM诱导的增殖，提示活化T细胞核因子（NFAT）/钙调神经磷酸酶参与其中。使用选择性抑制剂进一步表明该过程涉及其他信号通路。抑制磷脂酰肌醇3激酶和蛋白激酶A均可阻止804G-ECM刺激的β细胞复制。相反，抑制丝裂原活化蛋白激酶（MAPK）、c-Jun氨基末端激酶、p38和糖原合酶激酶-3β可增加804G-ECM上β细胞的增殖。我们的结果表明，804G-ECM上β细胞增殖增加所必需的Ca2+内流也参与了804G-ECM诱导的NF-κB活性。据推测，胞质Ca2+增加导致转录因子NFAT和NF-κB活化，进而增加β细胞增殖。804G-ECM激活磷脂酰肌醇3激酶也可能通过抑制糖原合酶激酶-3β协同共激活NFAT来增加增殖，而白细胞介素-1β可能通过NF-κB的前馈激活来放大这一过程。相反，抑制MAPK信号通路增加了β细胞增殖，表明该信号通路具有负调节作用。
