Manganese Regulates Manganese-Containing Superoxide Dismutase (MnSOD) Expression in the Primary Broiler Myocardial Cells

Abstract

Previous studies showed that dietary manganese can increase the MnSOD mRNA expression in a dose-dependent manner in the heart of broilers. In order to explore the specific mechanism of the MnSOD expression induced by manganese, a model of MnSOD expression was developed with primary cultured broiler myocardial cells. The objective of the present study was to investigate whether the model was working or not and to determine how manganese affects the expression of the enzyme in broiler myocardial cells in vitro. In experiment 1, various amount of manganese (0, 0.25, 0.5, 1, 2, and 4 mM) were added into the cultures for 24-h incubation to investigate MnSOD expression and for 0-, 6-, 12-, 24-, 36-, and 48-h incubation to measure the cell viability. In experiment 2, the most suitable Mn supplementation based on the results of experiment 1 was added into cultures for 6-, 12-, 24-, and 48-h incubation. The results showed that MnSOD mRNA, MnSOD protein, and MnSOD activity were induced by manganese in dose- and time-dependent manner. Manganese regulates MnSOD expression not only at transcriptional level but also at translational and/or posttranslational levels.

Antioxidant Systems in Poultry Biology: Superoxide Dismutase

“…For example, in primary cultured broiler myocardial cells Mn-SOD mRNA, Mn-SOD protein, and Mn-SOD activity were induced by manganese in dose-and time-dependent manner. Manganese regulates Mn-SOD expression not only at transcriptional level but also at translational and/or posttranslational levels [74]. In both heart and kidney, Mn-SOD activity was significantly depressed by decreased dietary manganese; greatest reduction occurred in the heart [75].…”

Manganese elevates manganese superoxide dismutase protein level through protein kinase C and protein tyrosine kinase

“…Our preliminary experiments showed that cells treated with 0.5 mmol/L inorganic MnCl 2 as long as 48 h had similar viability compared with those not treated with Mn (Gao et al 2011). The MnSOD protein level increased from 12 h, while MnSOD mRNA response occurred after stimulation with inorganic Mn until up to 24 h and kept on increasing by 48 h (Gao et al 2011).…”

“…Our preliminary experiments showed that cells treated with 0.5 mmol/L inorganic MnCl 2 as long as 48 h had similar viability compared with those not treated with Mn (Gao et al 2011). The MnSOD protein level increased from 12 h, while MnSOD mRNA response occurred after stimulation with inorganic Mn until up to 24 h and kept on increasing by 48 h (Gao et al 2011). Therefore, in Expt 1, the primary myocardial cells were cultured with serum-free medium for 12 h, and then treated with no Mn supplementation (C, medium) or 0.5 mmol/L of Mn as the inorganic MnCl 2 (I, reagent grade, Beijing Biochemical Reagent Company, Beijing, China) or one of three organic Mn sources for 12 or 48 h. The three organic Mn sources (chelates of Mn and amino acids) with weak (W, formation quotient (Q f ) = 2.35 lower than 10, containing Mn 7.49 % and total amino acids 30.42 %, Zinpro Corp.), moderate (M, Q f = 16.85 between 10 and 100, containing Mn 9.06 % and total amino acids 29.09 %, Sanbao Additive Company, Beijing, China), or strong (S, Q f = 147.00 between 100 and 1000, containing Mn 10.18 % and total amino acids 45.27 %, Alltech) chelation strengths were the same as those described by Li et al (2011).…”

“…Moreover, the organic Mn source chelated with amino acids with moderate chelation strength was more effective than inorganic Mn sulfate or the organic Mn sources with weak or strong chelation strength in activating heart MnSOD gene expression of broilers at both mRNA and protein levels (Li et al 2004(Li et al , 2005(Li et al , 2008Luo et al 2007). Previous in vitro study from our laboratory also indicated that Mn elevated MnSOD mRNA and protein levels, and its enzymatic activity in the primary broiler myocardial cells in dose-and timedependent manners (Gao et al 2011). However, the signaling pathways responsible for Mn-induced MnSOD mRNA and protein expressions in broiler heart are still unclear.…”

“…The primary myocardial cells were isolated from the heart tissue of 7-dayold male Arbor Acres broilers (Huadu Broiler Breeding Corp., Beijing, China) fed the Mn-deficient diet for 7 days as described previously (Gao et al 2011). The cardiac muscles were digested and the isolated cells were pooled for all tested parameters in each experiment.…”