Stanniocalcin-1 Protects Porcine Intestinal Epithelial Cells Against TBHP-Induced Oxidative Stress by Preserving Mitochondrial Homeostasis

Stanniocalcin‑1 (STC‑1) is a multifunctional glycoprotein, yet its role in mitigating intestinal epithelial oxidative injury remains elusive. This study investigated the cytoprotective effects and underlying molecular mechanisms of STC‑1 in porcine intestinal epithelial cells (IPEC‑J2) subjected to tert‑butyl hydroperoxide (TBHP)‑induced oxidative stress. IPEC‑J2 cells were transfected with pcDNA3.1/STC‑1 prior to the TBHP challenge. STC‑1 overexpression markedly rescued IPEC‑J2 cells from TBHP‑induced cytotoxicity and apoptosis, as demonstrated by AO/PI dual-staining and a restored Bax/Bcl‑2 ratio. Concurrently, STC‑1 dramatically suppressed intracellular reactive oxygen species and mitochondrial superoxide accumulation while preserving the mitochondrial membrane potential. These physiological improvements were accompanied by enhanced total antioxidant capacity and upregulated activities of key antioxidant enzymes. Mechanistically, mRFP‑GFP‑LC3 reporter assays revealed STC‑1 enhanced autophagic processing and promoted Pink1/Parkin-mediated mitophagy to clear dysfunctional mitochondria. Furthermore, STC‑1 enhanced the AMPK–Nrf2/Sirt1 signaling axis, leading to Keap1 downregulation and the subsequent transcription of mitochondrial biogenesis markers (FoxO1, PGC‑1α, and TFAM) under stress conditions. Taken together, these findings demonstrate that STC‑1 safeguards porcine intestinal epithelial cells against oxidative injury by orchestrating a cooperative defense network that involves ROS scavenging, mitochondrial homeostasis, and antioxidant defense amplification via AMPK–Nrf2/Sirt1 pathway, presenting a potential therapeutic target for preventing stress-associated intestinal disorders in piglets.