Expression of Mitochondrial Complex 1 Inhibitor in Bovine Liver Tissue, Primary Hepatic Cells and Detection of its Transcript in Conditioned Media Mimicking Fatty Liver Disease

Abstract

Mitochondrial complex I inhibitor (iC1) is a methylation‐controlled J protein that decreases oxidative phosphorylation of cellular respiration. Recent rodent studies showed loss or inhibition of iC1 was associated with prevention of lipid accumulation and T‐cell survival. One of the common metabolic disorder of dairy cattle is fatty liver disease (FLD), which often occurs during the periparturient period. Thus far, the evidence of iC1expression in bovine liver and its possible role in FLD development are not known. We hypothesized that iC1 expresses in bovine liver and associated with FLD during the periparturient period. We collected bovine liver tissue samples from abattoir and isolated primary hepatic cells using a simple nonperfusion‐based method. Primary hepatic cells were grown in presence of 0.4 mM palmitate, 20 ng/mL TNFα, and a cocktail of 0.4 mM palmitate and 20 ng/mL TNFα . The control cells grown in complete growth media (DMEM + 10% FBS +1x antibiotics) with no added treatments. For the first time, we 1) showed in vivo and in vitro expression of iC1 in bovine liver and 2) detected presence of iC1 specific transcript in aliquots of conditioned media of hepatic cells. Results of RT‐qPCR, immunocytochemistry and capillary‐based western blot showed expression of iC1 in bovine liver tissue and primary hepatic cells. Preliminary results of RT‐qPCR showed iC1 specific transcript amplification in conditioned media collected 24 h after treatments. Since the abundance of total RNA in conditioned media was lower, in comparison to the RNA from cell lysates, transcripts of iC1 was detectable at higher threshold cycle. The transcript of iC1 tended to be higher (4‐fold; p>0.05) in TNFα‐treated conditioned media vs. the control. Detection of iC1 transcript in hepatic cells and conditioned media is novel and may suggests iC1 expression by hepatic cells. Altogether, we showed expression of mitochondrial complex 1 inhibitor gene and protein in bovine liver tissue, primary hepatic cells and the conditioned media. Altering expression of iC1 to mitigate the metabolic disorder of fatty liver disease in periparturient dairy cows might be a noteworthy.