C1QTNF1 (C1q and TNF related 1) is a member of the CTRP superfamily that functions as a cardioprotective and metabolic regulatory protein. The protein is upregulated during cardiac hypertrophic processes triggered by reactive oxygen species and acts as a negative regulator of cardiomyocyte hypertrophy 1. C1QTNF1 attenuates angiotensin II-induced cardiac hypertrophy through activation of the AMPKα pathway, which subsequently inhibits mTOR P70S6K phosphorylation 1. This mechanism involves inhibition of PDE1-4, leading to cAMP/PKA/LKB1 pathway activation 1. In vascular tissue, C1QTNF1 regulates inflammatory gene expression in smooth muscle cells, with IL-6, CCL2, and ICAM1 identified as key target genes 2. The protein shows clinical significance as a biomarker, with elevated circulating levels associated with aortic stenosis progression and right ventricular dysfunction in pulmonary hypertension 34. Additionally, C1QTNF1 expression is induced by triiodothyronine treatment and is upregulated in osteoarthritis, suggesting roles in skeletal system development and hypertrophic chondrocyte differentiation 5. The protein demonstrates cardioprotective effects by improving cardiac function and inhibiting cardiac hypertrophy and fibrosis 1.