MOTS-c primes adrenal cortex metabolism without directly driving steroidogenesis.

Abstract

Introduction: Mitochondrial open reading frame of the 12S rRNA type-c (MOTS-c), a 16-amino acid mitochondrial-derived peptide, regulates cellular metabolism through AMPK and mTOR signaling and exerts protective effects across multiple endocrine tissues. However, its role in adrenal physiology remains unexplored. We hypothesized that MOTS-c establishes "steroidogenic readiness" by priming metabolic pathways rather than directly activating hormone synthesis.

Material and methods: Adult male Wistar rats (n = 16) received continuous MOTS-c (0.1 μmol/24 h) or saline via subcutaneous micro-osmotic pumps for 24 hours. Adrenal tissues were analyzed using qRT-PCR, immunohistochemistry, ELISA, and RNA-sequencing.

Results: MOTS-c showed significantly higher expression in ZF/ZR vs. ZG. MOTS-c treatment did not alter classical steroidogenic genes or circulating corticosterone and aldosterone levels. RNA-seq identified 39 differentially expressed genes, notably upregulation of purinergic receptor P2ry4 (4.3-fold, P < 0.05) - a novel MOTS-C target enhancing calcium signaling. Additional changes included upregulation of Apoc4 and downregulation of stress markers Bag3 and Smurf2, mitochondrial carrier Slc25a30, and peroxisomal factor Pex11a. Gene Set Enrichment Analysis revealed inhibition of cAMP response, mitophagy, and histone deacetylation pathways, alongside activation of cell proliferation, indicating metabolic reprogramming without steroidogenic activation.

Conclusions: MOTS-c functions as a metabolic conductor that primes adrenocortical cells for enhanced steroidogenic responsiveness without stimulating basal hormone synthesis. By upregulating calcium signaling, modulating lipid metabolism, downregulating stress-response proteins, and inhibiting mitophagy, MOTS-c establishes a preparatory metabolic state optimized for subsequent ACTH or stress stimulation. These findings reveal a novel preparatory mechanism in adrenal physiology and identify MOTS-c as a potential therapeutic target for HPA axis disorders requiring enhanced adrenal reserve capacity without basal hypercortisolemia.