OSTN (osteocrin) is a multifunctional secretory peptide that serves as both a myokine and hormone with diverse physiological roles. In skeletal muscle, OSTN functions as an exercise-responsive myokine that regulates muscle homeostasis by controlling fibro-adipogenic progenitor fate through the FILIP1L pathway 1 and negatively modulates beige fat thermogenesis via Tfr1/PKA signaling 2. In bone tissue, OSTN promotes osteocyte dendrite formation as a target gene of transcription factor Sp7, playing a crucial role in osteocytogenesis 3. The protein exerts cardioprotective effects by restoring proteasomal activity through PKG-dependent mechanisms in diabetic cardiomyopathy 4 and protecting against doxorubicin-induced cardiotoxicity by attenuating inflammation, oxidative stress, and apoptosis 5. Additionally, OSTN demonstrates renoprotective properties in adriamycin nephropathy through p38 MAPK inhibition 6. Mechanistically, OSTN functions by binding to natriuretic peptide receptor NPR-C, preventing natriuretic peptide degradation and enhancing cGMP signaling 6. OSTN expression has been identified in primate-specific activity-dependent sensory neurons 7, and cerebrospinal fluid OSTN levels are associated with neurological regulation and Alzheimer's disease 8.