Acyl CoA synthetase-1 links facilitated long chain fatty acid uptake to intracellular metabolic trafficking differently in hearts of male versus female mice

Abstract

Rationale Acyl CoA synthetase-1 (ACSL1) is localized at intracellular membranes, notably the mitochondrial membrane. ACSL1 and female sex are suggested to indirectly facilitate lipid availability to the heart and other organs. However, such mechanisms in intact, functioning myocardium remain unexplored, and roles of ACSL1 and sex in the uptake and trafficking of fats are poorly understood. Objective To determine the potential for ACSL1 and sex-dependent differences in metabolic trapping and trafficking effects of long-chain fatty acids (LCFA) within cardiomyocytes of intact hearts. Methods and Results 13C NMR of intact, beating mouse hearts, supplied 13C palmitate, revealed 44% faster trans-sarcolemmal uptake of LCFA in male hearts overexpressing ACSL1 (MHC-ACSL1) than in non-transgenic (NTG) males (P<0.05). Acyl CoA content was elevated by ACSL1 overexpression, 404% in males and 164% in female, relative to NTG. Despite similar ACSL1 content, NTG females displayed faster LCFA uptake kinetics compared to NTG males, which was reversed by ovariectomy. NTG female LCFA uptake rates were similar to those in ACSL1 males and ACSL1 females. ACSL1 and female sex hormones both accelerated LCFA uptake without affecting triglyceride content or turnover. ACSL1 hearts contained elevated ceramide, particularly C22 ceramide in both sexes and specifically, C24 in males. ACSL1 also induced lower content of fatty acid transporter-6 (FATP6) indicating cooperative regulation with ACSL1. Surprisingly, ACSL1 overexpression did not increase mitochondrial oxidation of exogenous palmitate, which actually dropped in female ACSL1 hearts. Conclusions ACSL1-mediated metabolic trapping of exogenous LCFA accelerates LCFA uptake rates, albeit to a lesser extent in females, which distinctly affects LCFA trafficking to acyl intermediates but not triglyceride storage or mitochondrial oxidation and is affected by female sex hormones.

ACSL1 Regulates TNFα-Induced GM-CSF Production by Breast Cancer MDA-MB-231 Cells

“…Our data show that pretreatment of the MDA-MB-231 cells with triacsin C, followed by the exposure to TNFα, caused a significant inhibition in the expression of GM-CSF (Figure 2A,B; p < 0.05). Since TNFα activates GM-CSF gene expression via ACSL1 which directs fatty acids towards β-oxidation [19] and ceramide production [20], we asked whether these components play a role in TNFα induced GM-CSF production. To this end, MDA-MB-231 cells were treated with inhibitors of fatty acid oxidation (etomoxir) or ceramide synthesis (myriocin) prior to incubation with TNFα.…”

“…Furthermore, ACSL1 deficiency prevents TNF𝛼 mediated induction of IL-1b and MCP-1 supporting the involvement of ACSL1 in the TNFα mediated production of cytokines and chemokines [16]. Since TNFα activates GM-CSF gene expression via ACSL1 which directs fatty acids towards β-oxidation [19] and ceramide production [20], MDA-Mb-231 cells were treated with inhibitors of fatty acid oxidation (etomoxir) or ceramide synthesis (myriocin) prior to incubation with TNFα. We found that etomoxir and myriocin did not block the TNFα induced production of GM-CSF.…”

Deciphering the Role of Lipid Droplets in Cardiovascular Disease

“…These genetic models have served as platforms for discovery of the pathophysiology of lipid overload in the heart, providing novel insights into the effects of different diet compositions as well as the crosstalk between sex hormones and lipid metabolism 2, 54 . In addition, a signature of metabolic and signaling pathways mediated by lipid overload in vivo has emerged.…”

Modulation of Fatty Acid-Related Genes in the Response of H9c2 Cardiac Cells to Palmitate and n-3 Polyunsaturated Fatty Acids

“…Indeed, non-surprisingly we observed that miR-33a expression showed the same pattern following exposure of H9c2 cells to saturated and polyunsaturated FAs. Long-chain acyl-CoA synthetase 1 (ACSL1) is an enzyme highly expressed in the heart catalyzing the activation of long chain FAs to acyl-CoA, a key step for further use of FAs [25,26]. Since EPA has been reported to suppress palmitate-induced expression of ACSL1 in macrophages, presumably via SREBP1a regulation [27], we have investigated the effect of palmitate and/or n-3 PUFAs on the expression of ACSL1 in H9c2 cells.…”