PKCepsilon-Related Proteins in Lung Fibrosis

Medical University Of South Carolina, Charleston SC

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Abstract

DESCRIPTION (provided by applicant): This RFA asks investigators to identify novel targets that play a role in fibrogenesis, then to validate that altering the expression or function of targets does indeed inhibit pulmonary fibrosis. We already have identified a set of interconnected novel targets and have partially validated one target. Our central target is the e isoform of protein kinase C (PKC-epsilon). Cells cultured from the fibrotic lung tissue of scleroderma patients have altered PKC-epsilon signaling. The extracellular matrix protein tenascin is overexpressed in scleroderma lung fibroblasts due to altered PKC-epsilon signaling. Altered PKC-epsilon signaling is also revealed by the facts that: 1) Curcumin, from the Indian spice turmeric, inhibits collagen expression in scleroderma lung fibroblasts then causes the cells to undergo apoptosis while normal lung fibroblasts are unaffected by curcumin; and 2) Scleroderma lung fibroblasts can be made curcumin-resistant by PKC-epsilon overexpression while PKC-epsilon depletion makes normal cells sensitive to curcumin. Moreover, three "binding partners" for PKC-epsilon (calponin, caveolin- 1, and RACK2) have altered levels of expression and subcellular localizations in scleroderma lung fibroblasts. The overexpression of tenascin and calponin in vivo has been confirmed in sections of lung tissue from scleroderma patients. Based on these observations, we will test the hypothesis that altering the expression or function of PKC-epsilon, of tenascin, or of binding partners for PKC-epsilon will inhibit pulmonary fibrosis. Experiments will be performed using: 1) Cultured lung fibroblasts from scleroderma patients and matched normal subjects and 2) Mice in which lung fibrosis in induced using bleomycin. Specifically we will: 1) Optimize the delivery of potential treatments via lentivirus into the lungs of mice. 2) Perturb PKC-epsilon expression and function using curcumin, using virus that enhance or inhibit PKC-epsilon expression, and using a peptide that blocks PKC-epsilon translocation and function. These experiments will include a determination of why scleroderma fibroblasts are particularly sensitive to curcumin. 3) Perturb the expression of PKC-epsilon binding partners using virus. 4) Inhibit tenascin expression using virus and test the idea that tenascin is a downstream mediator of the effects observed when PKC-epsilon expression is manipulated. The effects of these perturbations will be read out in terms of collagen expression and curcumin-induced apoptosis in cell cultures and in terms of survival, lung tissue morphology, and collagen levels in bleomycin-treated mice. These approaches will allow us to validate the role in lung fibrosis of the several target proteins that we have already identified.