CPT1B
Carnitine O-palmitoyltransferase 1, muscle isoform (EC 2.3.1.21) (CPT1-M) (Carnitine O-palmitoyltransferase I, muscle isoform) (CPT I) (CPTI-M) (Carnitine palmitoyltransferase 1B) (Carnitine palmitoyltransferase I-like protein) [KIAA1670]
Publications[править]
The carnitine palmitoyltransferase (CPT) family is essential for fatty acid oxidation. Recently, we found that CPT1C, one of the CPT1 isoforms, plays a vital role in cancer cellular senescence. However, it is unclear whether other isoforms (CPT1A, CPT1B, and CPT2) have the same effect on cellular senescence. This study illustrates the different effects of CPT knockdown on PANC-1 cell proliferation and senescence and MDA-MB-231 cell proliferation and senescence, as demonstrated by cell cycle kinetics, Bromodeoxyuridine incorporation, senescence-associated β-galactosidase activity, colony formation, and messenger RNA (mRNA) expression of key senescence-associated secretory phenotype factors. CPT1C exhibits the most substantial effect on cell senescence. Lipidomics analysis was performed to further reveal that the knockdown of CPTs changed the contents of lipids involved in mitochondrial function, and lipid accumulation was induced. Moreover, the different effects of the isoform deficiencies on mitochondrial function were measured and compared by the level of radical oxygen species, mitochondrial transmembrane potential, and the respiratory capacity, and the expression of the genes involved in mitochondrial function were determined at the mRNA level. In summary, CPT1C exerts the most significant effect on mitochondrial dysfunction-associated tumor cellular senescence among the members of the CPT family, which further supports the crucial role of CPT1C in cellular senescence and suggests that inhibition of CPT1C may represent as a new strategy for cancer treatment through the induction of tumor senescence.
MeSH Terms
- Breast Neoplasms
- Carnitine O-Palmitoyltransferase
- Cell Line, Tumor
- Cell Proliferation
- Cellular Senescence
- Energy Metabolism
- Female
- Gene Expression Regulation, Neoplastic
- Humans
- Lipid Metabolism
- Mitochondria
- Pancreatic Neoplasms
- Proto-Oncogene Proteins c-myc
- Signal Transduction
Keywords
- carnitine palmitoyltransferase (CPT)
- cellular senescence
- lipidomics
- mitochondrial function
Recent studies have indicated that serum testosterone in aging men is associated with insulin sensitivity and expression of genes involved in oxidative phosphorylation (OxPhos), and that testosterone treatment increases lipid oxidation. Herein, we investigated the effect of testosterone therapy on regulators of mitochondrial biogenesis and markers of OxPhos and lipid metabolism in the skeletal muscle of aging men with subnormal bioavailable testosterone levels. Skeletal muscle biopsies were obtained before and after treatment with either testosterone gel (n=12) or placebo (n=13) for 6 months. Insulin sensitivity and substrate oxidation were assessed by euglycemic-hyperinsulinemic clamp and indirect calorimetry. Muscle mRNA levels and protein abundance and phosphorylation of enzymes involved in mitochondrial biogenesis, OxPhos, and lipid metabolism were examined by quantitative real-time PCR and western blotting. Despite an increase in lipid oxidation (P<0.05), testosterone therapy had no effect on insulin sensitivity or mRNA levels of genes involved in mitochondrial biogenesis (PPARGC1A, PRKAA2, and PRKAG3), OxPhos (NDUFS1, ETFA, SDHA, UQCRC1, and COX5B), or lipid metabolism (ACADVL, CD36, CPT1B, HADH, and PDK4). Consistently, protein abundance of OxPhos subunits encoded by both nuclear (SDHA and UQCRC1) and mitochondrial DNA (ND6) and protein abundance and phosphorylation of AMP-activated protein kinase and p38 MAPK were unaffected by testosterone therapy. The beneficial effect of testosterone treatment on lipid oxidation is not explained by increased abundance or phosphorylation-dependent activity of enzymes known to regulate mitochondrial biogenesis or markers of OxPhos and lipid metabolism in the skeletal muscle of aging men with subnormal bioavailable testosterone levels.
MeSH Terms
- Aging
- Blotting, Western
- Body Composition
- Electrophoresis, Polyacrylamide Gel
- Lipid Metabolism
- Muscle, Skeletal
- Oxidative Phosphorylation
- Real-Time Polymerase Chain Reaction
- Testosterone