INSIG1 and renal fibrosis: We used PTCs-specific and fibroblast-specific Insig1-knockout mice and whole-body Aldh1a1-knockout mice subjected to UUO or 5/6 nephrectomy (5/6 Nx) to evaluate the importance of PTC-specific Insig1 in conferred protection against renal fibrosis and the maintenance of NAD+ homeostasis.