Mitochondrial trans-2-enoyl-CoA reductase (MECR) is involved in mitochondrial synthesis of fatty acids and is highly expressed in mitochondria. MECR is also known as nuclear receptor binding factor-1, which was originally reported with yeast two-hybrid screening as a binding protein of the nuclear hormone receptor peroxisome proliferator-activated receptor α (PPARα). However, MECR and PPARα are localized at different compartment, mitochondria, and the nucleus, respectively. Therefore, the presence of a cytosolic or nuclear isoform of MECR is necessary for functional interaction between MECR and PPARα.
To identify the expression pattern of MECR and the cytosolic form of MECR (cMECR), we performed reverse transcription polymerase chain reaction (RT-PCR) with various tissue samples from Sprague-Dawley rats. To confirm the interaction between cMECR and PPARα, we performed several binding assays such as yeast two-hybrid, coimmunoprecipitation, and bimolecular fluorescence complementation. To observe subcellular localization of these proteins, immunocytochemistry was performed. A luciferase assay was used to measure PPARα activity.
We provide evidence of an alternatively spliced variant of the rat MECR gene that yields cMECR. The cMECR lacks the N-terminal 76 amino acids of MECR and shows uniform distribution in the cytoplasm and nucleus of HeLa cells. cMECR directly bound PPARα in the nucleus and increased PPARα-dependent luciferase activity in HeLa cells.
We found the cytosolic form of MECR (cMECR) was expressed in the cytosolic and/or nuclear region, directly binds with PPARα, and enhances PPARα activity.
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The glucose transporters (GLUTs) exhibit different tissue-specific expression. This study aimed to investigate the types of GLUTs expressed in human granulosa cells (GCs) obtained from women with polycystic ovary syndrome (PCOS) and their relationship with insulin resistance (IR) and the outcomes of
Expression of GLUTs was evaluated in GCs from women with PCOS with or without IR. Thirty-six women with PCOS undergoing an IVM program were included. Differential gene expression between the insulin sensitive (IS) and IR group was measured by reverse transcription polymerase chain reaction.
Expression of GLUTs 1, 3, 5, 8, and 13 was constitutive, whereas expression of GLUTs 2 and 7 was not observed in human GCs. The remaining GLUTs, 4, 6, 9, 10, 11, and 12, were differentially expressed among patients according to metabolic status, such as insulin sensitivity. A higher number of GCs from patients with IR (92%) expressed GLUT6 than GCs from IS PCOS patients (46.3%). Logistic regression showed that expression of GLUTs 9, 11, and 12 correlates with rates of IVM at 48 hours, fertilization, and implantation, respectively.
This is the first report describing the expression pattern of all 13 members of the GLUT family in human GCs. Results of the present study suggest that patients' insulin sensitivity regulates GLUT expression in GCs in PCOS patients, and this may control oocyte quality for IVM and subsequent processes such as fertilization and implantation in patients taking part in an
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