Reduced Expression of Collagen VI Alpha 3 (COL6A3) Confers Resistance to Inflammation-Induced MCP1 Expression in Adipocytes

Obesity. 2016 Aug;24 (8), 1695-703

Stephane Gesta, Kalyani Guntur, Ishita Deb Majumdar, Syamala Akella, Vivek K. Vishnudas, Rangaprasad Sarangarajan, Niven R. Narain

Objective: Collagen VI alpha 3 (COL6A3) is associated with insulin resistance and adipose tissue inflammation. In this study, the role of COL6A3 in human adipocyte function was characterized.

Methods: Immortalized human preadipocyte cell lines stably expressing control or COL6A3 shRNA were used to study adipocyte function and inflammation.

Results: COL6A3 knockdown increased triglyceride content, lipolysis, insulin-induced Akt phosphorylation, and mRNA expression of key adipogenic genes (peroxisome proliferator-activated receptor-γ, glucose transporter, adiponectin, and fatty acid binding protein), indicating increased adipocyte function and insulin sensitivity. However, COL6A3 knockdown decreased basal adipocyte chemokine (C-C motif) ligand 2 [CCL2, monocyte chemoattractant protein (MCP1)] mRNA expression, reduced secreted protein levels, and abrogated tumor necrosis factor-α- and lipopolysaccharide-induced MCP1 mRNA expression. In addition, while control adipocytes co-cultured with THP1 macrophages showed a threefold increase in adipocyte MCP1 mRNA expression, in COL6A3 knockdown adipocytes MCP1 mRNA expression was unaltered by co-culturing. Lastly, in normal differentiated adipocytes, matrix metalloproteinase-11 treatment reduced expression of COL6A3 protein, MCP1 mRNA, MCP1 secretion, and abrogated tumor necrosis factor-α- and lipopolysaccharide-induced MCP1 mRNA expression and protein secretion.

Conclusions: COL6A3 knockdown in adipocytes leads to the development of a unique state of inflammatory resistance via suppression of MCP1 induction.

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