TGF‐β induced hyaluronan synthesis in orbital fibroblasts involves protein kinase C βII activation in vitro

Abstract

Graves' ophthalmopathy is accompanied by hyaluronan (HA) accumulation in the orbital space and infiltration of immunocompetent cells and cytokines, including IFN-gamma, IL-1beta, and TGF-beta. We examined the signal transduction pathways by which TGF-beta induces HA synthesis in normal orbital fibroblasts, orbital fibroblasts from patients with Graves' ophthalmopathy, and abdominal fibroblasts. Calphostin C inhibited the stimulation of HA synthesis by TGF-beta. Phorbol 12-myristate 13-acetate (PMA) activation of PKC stimulated HA production. The effects of TGF-beta and PMA were not synergistic. Stimulation by TGF-beta and PMA were dependent on protein synthesis and their effects were inhibited by cycloheximide. Since TGF-beta-induced HA synthesis was inhibited by BAPTA or by PKC inhibitors, a calcium-dependent PKC was most likely involved. The PKA inhibitor H-89 enhanced TGF-beta- and PMA-induced HA synthesis, thus showing that communication between the PKA and PKC pathways was evident. TGF-beta stimulated the translocation of PKCbetaII to the cell membrane. PKCbetaII, a key enzyme in the regulation of HA synthesis by TGF-beta, might be an appropriate target for therapeutic compounds to be used to treat Graves' ophthalmopathy accompanied by inflammation.

High glucose activates PKC-ζ and NADPH oxidase through autocrine TGF-β1 signaling in mesangial cells

“…TGF-␤ 1 has been reported to enhance the activity of isolated PKC isozymes in various cell types (28,59) and, in particular, PKC-␦ in mesangial cells (19). Differences in the incubation conditions or cell lines used could explain the more widespread PKC activation by TGF-␤ 1 observed in the present experiments compared with the study by Hayashida et al (19).…”

Cell density-dependent stimulation of PAI-1 and hyaluronan synthesis by TGF-β in orbital fibroblasts

“…We think that the high PAI-1 concentration in the GO orbit acts toward increased matrix stability, which may contribute to matrix expansion. Enhanced HA synthesis was described in OFs cultured in serum-free medium with TGF-β (Wang et al 2005, Guo et al 2011. We found that under basic circumstances, HA production per cell did not show a cell density-dependent pattern but was highly dependent on the origin of fibroblasts (Fig.…”

Mechanosensitive synoviocytes: A Ca2+–PKCα–MAP kinase pathway contributes to stretch-induced hyaluronan synthesis in vitro

“…BAPTA likewise inhibits IL-1β-or TGFβ-stimulated qḢ A in orbital fibroblasts, where the response is mediated by Ca 2+ -dependent PKCβII (Wong et al, 2001;Wang et al, 2005). It is possible, however, that BAPTA may also inhibit PKC through additional mechanisms (Dieter et al, 1993).…”