Phosphatidylinositol 3-kinase/Akt signaling mediates interleukin-32alpha induction in human pancreatic periacinar myofibroblasts.
Interleukin (IL)-32 is a recently described proinflammatory cytokine, characterized by the induction of nuclear factor (NF)-kappaB activation. We studied IL-32alpha expression in human pancreatic periacinar myofibroblasts, which play important roles in the regulation of extracellular matrix metabolism and inflammatory responses in the pancreas. IL-32alpha protein expression was evaluated by Western blot analyses, and IL-32alpha mRNA expression was analyzed by Northern blot and real-time PCR analyses. IL-32alpha mRNA was weakly expressed without a stimulus, and its expression was markedly enhanced by IL-1beta, IFN-gamma, and TNF-alpha. IL-1beta, IFN-gamma, and TNF-alpha enhanced intracellular accumulation of IL-32alpha protein, but IL-32alpha was not detected in supernatants. Each cytokine dose and time dependently induced IL-32alpha mRNA expression. An inhibitor of phosphatidylinositol 3-kinase (LY294002) significantly suppressed IL-1beta-, IFN-gamma-, and TNF-alpha-induced IL-32alpha mRNA expression, although MAPK inhibitors had no effect. Akt activation in response to these cytokines was confirmed by Western blot. Furthermore, LY294002 suppressed both IL-1beta- and TNF-alpha-induced NF-kappaB activation and IL-1beta-, TNF-alpha-, and IFN-gamma-induced activated protein-1 (AP-1) activation. Blockade of NF-kappaB and AP-1 activation by an adenovirus expressing a stable mutant form of IkappaBalpha and a dominant negative mutant of c-Jun markedly suppressed IL-1beta-, IFN-gamma-, and/or TNF-alpha-induced IL-32alpha mRNA expression. Human pancreatic periacinar myofibroblasts expressed IL-32alpha in response to IL-1beta, TNF-alpha, and IFN-gamma. IL-32alpha mRNA expression is dependent on interactions between the phosphatidylinositol 3-kinase/Akt-pathway and the NF-kappaB/AP-1 system.
Nishida
Atsushi
A
Department of Medicine, Shiga University of Medical Science, Seta-Tukinowa, Otsu 520-2192, Japan.
Andoh
Akira
A
Shioya
Makoto
M
Kim-Mitsuyama
Shokei
S
Takayanagi
Atsushi
A
Fujiyama
Yoshihide
Y
D000199:Actins / Q000378:metabolism; D000256:Adenoviridae / Q000235:genetics; D015153:Blotting, Western; D002467:Cell Nucleus / Q000502:physiology; D002478:Cells, Cultured; D016207:Cytokines / Q000096:biosynthesis / Q000494:pharmacology; D024202:Electrophoretic Mobility Shift Assay; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005109:Extracellular Matrix / Q000502:physiology; D005347:Fibroblasts / Q000378:metabolism*; D006801:Humans; D007202:Indicators and Reagents; D007378:Interleukins / Q000096:biosynthesis*; D020928:Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors; D009130:Muscle, Smooth / Q000378:metabolism; D051058:Oncogene Protein v-akt / Q000502:physiology*; D010179:Pancreas / Q000166:cytology / Q000378:metabolism*; D019869:Phosphatidylinositol 3-Kinases / Q000502:physiology*; D000081082:Phosphoinositide-3 Kinase Inhibitors; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction / Q000502:physiology*; D018808:Transcription Factor AP-1 / Q000502:physiology
D000199:Actins; D016207:Cytokines; D004791:Enzyme Inhibitors; D007202:Indicators and Reagents; D007378:Interleukins; D020928:Mitogen-Activated Protein Kinases; D051058:Oncogene Protein v-akt; D019869:Phosphatidylinositol 3-Kinases; D000081082:Phosphoinositide-3 Kinase Inhibitors; D018808:Transcription Factor AP-1; C496971:IL32 protein, human