Steroidogenesis in MA-10 mouse Leydig cells is altered via fatty acid import into the mitochondria.

Abstract

Mitochondria are home to many cellular processes, including oxidative phosphorylation and fatty acid metabolism, and in steroid-synthesizing cells, they are involved in cholesterol import and metabolism, which is the initiating step in steroidogenesis. The formation of macromolecular protein complexes aids in the regulation and efficiency of these mitochondrial functions, though because of their dynamic nature, they are hard to identify. To overcome this problem, we used Blue-Native PAGE with whole-gel mass spectrometry on isolated mitochondria from control and hormone-treated MA-10 mouse tumor Leydig cells. The presence of multiple mitochondrial protein complexes was shown. Although these were qualitatively similar under control and human chorionic gonadotropin (hCG)-stimulated conditions, quantitative differences in the components of the complexes emerged after hCG treatment. A prominent decrease was observed with proteins involved in fatty acid import into the mitochondria, implying that mitochondrial beta-oxidation is not essential for steroidogenesis. To confirm this observation, we inhibited fatty acid import utilizing the CPT1a inhibitor etomoxir, resulting in increased steroid production. Conversely, stimulation of mitochondrial beta-oxidation with metformin resulted in a dose-dependent reduction in steroidogenesis. These changes were accompanied by changes in mitochondrial respiration and in the lactic acid formed during glycolysis. Taken together, these results suggest that upon hormonal stimulation, mitochondria efficiently import cholesterol for steroid production at the expense of other lipids necessary for energy production, specifically fatty acids required for beta-oxidation.

• Authors: Malena B Rone, Andrew S Midzak, Daniel B Martinez-Arguelles, Jinjiang Fan, Xiaoying Ye, Josip Blonder, Vassilios Papadopoulos
• Journal: Biology of reproduction (Biol Reprod) Vol. 91 Issue 4 Pg. 96 (Oct 2014) ISSN: 1529-7268 [Electronic] United States
• PMID: 25210128 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)
• Copyright: © 2014 by the Society for the Study of Reproduction, Inc.

Chemical References

• Fatty Acids
• Hypoglycemic Agents
• Steroids
• Metformin

Topics

• Animals
• Biological Transport
• Cell Line
• Fatty Acids (metabolism)
• Gene Expression Regulation (drug effects, physiology)
• Hypoglycemic Agents (pharmacology)
• Leydig Cells (metabolism)
• Male
• Metformin (pharmacology)
• Mice
• Mitochondria (metabolism)
• Oxidation-Reduction
• Steroids (biosynthesis)
• Transcriptome