Abstract #M18

# M18
Fetuin-A modulates lipid mobilization in bovine adipose tissue by enhancing lipogenic activity of adipocytes.
Clarissa Strieder-Barboza*1, G. Andres Contreras1, 1Department of Large Animal Clinical Sciences, Michigan State University, East Lansing, MI.

Fetuin-A (FetA) is an adipokine and free fatty acids (FFA) transporter linked to adipose tissue (AT) function in transition cows. Plasma and AT FetA decrease after parturition coinciding with reduced lipogenesis and increased lipolysis. In monogastrics, FetA enhances lipogenesis, but its role on lipid mobilization of ruminants is unclear. Our objective was to determine the effects of FetA on lipogenesis and lipolysis in bovine adipocytes. Preadipocytes from tailhead subcutaneous AT of dairy cows (n = 6) were induced to differentiate in a coculture system and used in the experiments. Lipolytic responses of adipocytes were evaluated after a 2-h β-adrenergic stimulation with 1 µM isoproterenol (lSO) alone or combined with 0.1 mg/mL of FetA (FETA+ISO). Medium alone (CON) or mixed with 0.1 mg/mL of FetA (FETA) served as controls. Lipogenic responses were assessed in adipocytes treated with CON or FETA for 48 h by quantification of FFA uptake (kinetic assay for 1h) and triacylglycerol (TG) accumulation (Adipored) and gene (qPCR) and protein expression (Western blot) of lipogenic markers. Adrenergic stimulation with ISO increased lipolysis compared with CON, as reflected in the release of glycerol (12 ± 0.04 vs 0.04 ± 0.02 nM/cell, P = 0.003) and FFA (15 ± 13 vs 6.2 ± 2.4 nM/cell, P = 0.04). Lipolysis induced by ISO was attenuated by FetA (FETA+ISO) as reflected by a lower glycerol (0.06 ± 0.04 nM/cell, P = 0.02) and FFA (5.7 ± 2.7 nM/cell, P = 0.01) release. The treatment with FetA enhanced lipogenic responses compared with CON as demonstrated by a 1.5 times increment in FFA uptake (P = 0.02) and TG accumulation (P = 0.05); and the upregulation of 1-acylglycerol-3-phosphate acyltransferase (AGAPT2) gene expression (P = 0.04) and protein content (P = 0.08). In conclusion, FetA attenuates lipolytic response and enhances lipogenesis in bovine adipocytes. The upregulation of the rate-limiting lipogenic enzyme AGAPT2 by FetA suggests a potential pathway by which this adipokine promotes TG synthesis in adipocytes.

Key Words: adipokine, adipocyte, lipid mobilization