Biology subjects

Katoh, D.

Publications and source records attributed to Katoh, D..

3 recordsLinked to original sources

bioRxiv2026

Mitochondrial control of amino acid catabolism by a fasting-inducible mitochondrial carrier

Metabolic adaptation to nutrient deprivation requires coordinated control of mitochondrial anaplerosis and cataplerosis; however, how metabolite flux across the mitochondrial membrane is regulated during fasting remains less defined. Here, we report SLC25A34 as a fasting-inducible mitochondrial carrier that is highly expressed in oxidative skeletal muscle. Using bacterial reconstitution, proteo-liposomes, and tracer studies, we showed that SLC25A34 mediates the import of phosphoenolpyruvate (PEP) into the mitochondrial matrix. Loss of SLC25A34 impaired glutamine-supported anaplerosis under nutrient-deprived conditions, while glucose and pyruvate utilization remained largely intact. Muscle-specific deletion of Slc25a34 resulted in reduced fasting-induced amino acid catabolism and the accumulation of amino acids, leading to activation of mTORC1 signaling even under fasted conditions. Consequently, SLC25A34-deficient soleus muscle exhibited hypertrophy and myopathic features, accompanied by mTORC1-dependent increase in protein synthesis. Together, these results highlight a unique biological role for the inducible mitochondrial carrier SLC25A34, which couples PEP import to amino acid catabolism and proteostasis to preserve skeletal muscle integrity in response to metabolic stress. TeaserMitochondrial metabolite transport is tailored to meet muscle-specific needs for utilizing amino acids during fasting.

physiology↗

bioRxiv2025

Mitochondrial control of fuel switching via carnitine biosynthesis

Environmental adaptation often involves a shift in energy utilization toward mitochondrial fatty acid oxidation, which requires carnitine. Besides dietary sources of animal origin, carnitine biosynthesis from trimethyllysine (TML) is essential, particularly for those who consume plant-based diets; however, its molecular regulation and physiological role remain elusive. Here, we identify SLC25A45 as a mitochondrial TML carrier that controls carnitine biosynthesis and fuel switching. SLC25A45 deficiency decreased the carnitine pool and impaired mitochondrial fatty acid oxidation, shifting reliance to carbohydrate metabolism. Slc25a45-deficient mice were cold-intolerant and resistant to lipid mobilization by GLP1 receptor agonist (GLP-1RA), rendering them resistant to adipose tissue loss. Our study suggests that mitochondria serve as a regulatory checkpoint in fuel switching, with implications for metabolic adaptation and the efficacy of GLP-1RA-based anti-obesity therapy.

biochemistry↗

bioRxiv2025

Mitochondria-derived PEP licenses glycerolipid synthesis via SLC25A35

Mitochondria provide a variety of metabolites, in addition to ATP, to meet cell-specific needs. One such metabolite is phosphoenolpyruvate (PEP), which contains a higher-energy phosphate bond than ATP and has diverse biological functions. However, how mitochondria-generated PEP is delivered to the cytosol and fulfills cell-specific requirements remains elusive. Here, we show that SLC25A35 regulates mitochondrial PEP efflux and glyceroneogenesis in lipogenic cells that utilize the pyruvate-to-PEP bypass. Reconstitution and structural studies demonstrated PEP transport by SLC25A35 in a pH gradient-dependent manner. Loss of SLC25A35 in adipocytes impaired the conversion of mitochondrial PEP into glycerol-3-phosphate, thereby reducing glycerolipid synthesis. Significantly, hepatic inhibition of SLC25A35 in obese mice alleviated steatosis and improved systemic glucose homeostasis. Together, these results suggest that mitochondria facilitate glycerolipid synthesis by providing PEP via SLC25A35, offering lipogenic mitochondria as a target to limit glycerolipid synthesis, a pivotal step in the pathogenesis of hepatic steatosis and Type 2 diabetes.

cell biology↗