Patient-derived human induced pluripotent stem cell podocytes uncover endoplasmic reticulum and oxidative...

X-linked Alport syndrome (XLAS) is an inherited nephropathy caused by pathogenic COL4A5 variants that lead to podocyte dysfunction and progressive kidney failure. However, the involvement of endoplasmic reticulum (ER) stress and oxidative stress in the development of XLAS remains insufficiently understood. This study aims to elucidate the contribution of ER and oxidative stress to podocyte injury in XLAS employing a patient-derived human induced pluripotent stem cell (hiPSC)-based podocyte model.

Induced pluripotent stem cells were derived from XLAS patient blood cells and differentiated into podocytes (XLAS podocyte). Expression of pluripotency, lineage-specific, and podocyte markers was confirmed. ER stress, oxidative stress, and mitochondrial morphology were assessed through molecular characterization, imaging, and functional assays, comparing XLAS podocytes to wild-type (WT) hiPSC-derived podocytes.

XLAS patient-derived hiPSCs maintained typical pluripotency markers, exhibited normal karyotypes, and allowed for successful tri-lineage differentiation. Relative to WT podocytes, XLAS podocytes had diminished expression of NPHS1, WT1, and COL4A5, while COL4A1 was increased. ER stress marker expression was elevated, with lower levels of CANX and CALR, indicative of unfolded protein response (UPR) activation. Electron microscopy analysis demonstrated enhanced ER enlargement in XLAS podocyte, implicating ER stress in disease pathogenesis. Moreover, XLAS podocytes showed markedly raised oxidative stress markers and mitochondrial reactive oxygen species (ROS) levels, together with altered catalase protein expression. Viability assays further supported ER and oxidative stress as contributors to reduced podocyte survival in XLAS podocyte.

Our findings indicate that ER stress and oxidative stress are critical drivers of podocyte dysfunction in XLAS. UPR activation, ROS accrual, and mitochondrial impairment point to important therapeutic opportunities.