RNase P generated tRF(Ser-GCT) promotes fat storage in adipocytes via Adrb2 signaling.

tRNA-derived small RNAs (tsRNAs) are emerging regulators of metabolism, but their roles in adipose tissue are not well defined. Here, we profiled tsRNA expression in mouse brown adipose tissue (BAT), gonadal white adipose tissues, and inguinal white adipose tissue (iWAT), revealing depot-specific patterns and a notable enrichment of mitochondrial tRF-5c fragments, especially tRF-1:29-chrM.Ser-GCT (tRF(Ser-GCT)), in BAT. tRF(Ser-GCT) expression correlated with mitochondrial abundance and increased during adipogenic differentiation and metabolic activation, both in vivo and in vitro. Functionally, tRF(Ser-GCT) promoted adipogenesis and lipid accumulation in 3T3-L1 cells and localized to mitochondria. Mechanistically, tRF(Ser-GCT) is generated from mitochondrial tRNA(Ser-GCT) by the Ribonuclease P complex (Trmt10c, Hsd17b10, Prorp), with Hsd17b10 being essential for its biogenesis and for normal adipocyte lipid metabolism. tRF(Ser-GCT) directly targets and downregulates Adrenoceptor Beta 2, a key metabolic regulator. In vivo, restoring tRF(Ser-GCT) in Hsd17b10-deficient mice partially rescued adipose tissue accumulation and adipogenic gene expression. Together, these findings identify tRF(Ser-GCT) as a mitochondrial tsRNA that promotes adipogenesis via the Ribonuclease P - Adrenoceptor Beta 2 axis, revealing a new layer of tsRNA-mediated regulation in adipose tissue biology.