Mechanism of Akt regulation of the expression of collagens and MMPs in conjunctivochalasis

Akt is a central node of many signaling pathways, which plays important roles in cell survival, proliferation, migration, metabolism and collagen synthesis. Conjunctivochalasis (CCH) is one of the most common age-related ocular superficial diseases related to abnormalities in conjunctival extracellular matrix. Here, we studied the role of Akt regulating collagens and MMPs in the pathogenesis of CCH. Primary conjunctival fibroblasts were obtained from CCH patients (n = 13) and age-matched normal controls (n = 10). The levels of Akt, collagen type I, collagen type III, MMP1, and MMP3 were determined by Western blot, qRT-PCR, immunohistochemistry, and immunofluorescence staining. Normal control conjunctival fibroblasts were treated with Akt inhibitor A6730, and CCH fibroblasts were transfected with Akt overexpression vector. The expression of Akt in CCH was significantly lower than that in normal control of conjunctival tissues and cultured fibroblasts. Blocking Akt signaling with Akt inhibitor could inhibit the expression of collagen type I and collagen type III and upregulate the expression of MMP1 and MMP3. Meanwhile, compared with CCH fibroblasts transfected with control mimics, the protein and mRNA expression of collagen type I and collagen type III were increased significantly in Akt overexpression group, while the results of MMP1 and MMP3 in transfected fibroblasts were opposite. Taken together, Akt upregulated the expression of collagen type I and collagen type III and downregulated the expression of MMP1 and MMP3. Akt signaling pathway could provide a direct negative contribution to CCH and might be an attractive target for CCH therapy.