Abstract Body (Do not enter title and authors here): BACKGROUND
Obesity-related kidney disease (ORKD) retains pathological characteristics, including abnormal lipid accumulation in the kidney, whereas it remains uncertain which cell type may have adipogenic potential that is responsible for the ORKD.
Primary cilia (PC) are cellular structures that extend outward from the plasma membrane and act as a signaling center. We reported the role of PC in diet-induced obesity and adipogenesis via Trichoplein (TCHP), an inhibitory module of PC. We investigate the type of cell population that retains the adipogenic potential of the kidney and is responsible for the pathogenesis of the ORKD, in which the role of PC in adipogenesis using TCHP knockout mice.
METHODS
First, to screen the adipogenic cells, we established a primary culture from the whole kidneys of mice with or without obesity induced by a high-fat diet. Adipogenesis of each cell culture was induced by the induction media, including insulin, dexamethasone, and IBMX, and assessed by Bodipy staining. The cell type was confirmed by the immunostaining of specific markers, namely, CK-8/18 and AQP-1 for epithelial cells, α-SMA and desmin for mesangial cells, and nephrin for podocytes. The impact of trichoplein (TCHP) depletion was assessed through in vivo TCHP knockout mouse experiments and in vitro siRNA experiments. Single-cell analyses of the human renal epithelial cell population from health and obesity-diabetes were performed using a public database.
RESULT
We successfully isolated a cell population from mouse kidneys that exhibited adipogenic potential and were positive for CK-8/18 and AQP-1, indicating their proximal tubular origin.
The renal proximal epithelial cells from TCHP-KO exhibited significantly less adipogenesis, accompanied by an enhanced PC count and length. The adipogenic markers CEBP and FABP4 were consistently downregulated in the TCHP-KO mice. Interestingly, the expression level of the bodipy remained unchanged in TCHO mice as compared to the non-obese counterpart. In-vivo models as well as scRNA analysis of publicly available data confirmed this trend of adipogeniety. Single-cell analysis of the human database revealed that the epithelial cell population of type 2 diabetes patients exhibited an increase in the CEBP/FABP4.
Conclusion
Renal proximal epithelial cells is essential for the pathogenesis of ORKD via its adipogeneity in a PC-dependent and CEBP/FABP4-sensitive transcriptional pathway, independent of the lipid droplet formation process.