SPAG5‐AS1 inhibited autophagy and aggravated apoptosis of podocytes via SPAG5/AKT/mTOR pathway

Abstract

Objectives Podocyte injury is a prediction marker of diabetic nephropathy (DN), and AKT/mTOR pathway–mediated inhibition of autophagy is widely reported to contribute to podocyte damage. Recent study stated that sperm‐associated antigen 5 (SPAG5) activated AKT/mTOR signalling in bladder urothelial carcinoma, indicating SPAG5 might regulate autophagy and play a role in podocyte damage. Materials and methods Apoptosis and autophagy of human podocytes (HPCs) were detected by flow cytometry and immunofluorescence (IF). Gene level was assessed by Western blot and RT‐qPCR. Molecular interactions were determined by pulldown, RNA immunoprecipitation (RIP), co‐immunoprecipitation (co‐IP), chromatin immunoprecipitation (ChIP) and luciferase reporter assays. Results SPAG5 mRNA and protein levels were upregulated under high glucose treatment in HPCs. Silencing SPAG5 reversed the increase of apoptosis and decrease of autophagy in high glucose–treated HPCs. Later, we found a long non‐coding RNA (lncRNA) SPAG5 antisense RNA1 (SPAG5‐AS1) as a neighbour gene to SPAG5. Mechanistically, YY1 transcriptionally upregulated SPAG5‐AS1 and SPAG5 in high glucose–treated podocytes. SPAG5‐AS1 acted as a competitive endogenous RNA (ceRNA) to regulate miR‐769‐5p/YY1 axis and induce SPAG5. SPAG5‐AS1 interacted with ubiquitin‐specific peptidase 14 (USP14) and leads to de‐ubiquitination and stabilization of SPAG5 protein. Conclusions This study revealed that SPAG5‐AS1 inhibited autophagy and aggravated apoptosis of podocytes via SPAG5/AKT/mTOR pathway, indicating SPAG5‐AS1/SPAG5 as a potential target for the alleviation of podocyte injury and offering new thoughts for the treatments of DN.

Single-nuclear transcriptomics reveals diversity of proximal tubule cell states in a dynamic response to acute kidney injury

“…Interestingly, the S1 cluster 7 and the S2/3 cluster 3 showed enrichment of "respiratory chain," "mitochondrial inner membrane," and "cytochrome c oxidase activity" (Dataset S2), possibly indicating increased energy demand in these cells. Spag5, encoding a mitotic spindle protein shown to be up-regulated in response to oxidative stress in cancer (26) and in response to high glucose treatment in human podocytes (27), was overrepresented in these clusters as well as in cluster 8 (Fig. 2B).…”

sPLA2‐IB and PLA2R mediate insufficient autophagy and contribute to podocyte injury in idiopathic membranous nephropathy by activation of the p38MAPK/mTOR/ULK1 ser757 signaling pathway

“…35 Hyperactivity of mTOR and it also regulated the podocyte autophagy deficiency in response to stimuli's. 36,37 In the present sudy, mTOR and ULK1 ser757 phosphorylation were increased, and autophagy decreased by the in stimulation of sPLA2-IB and rapamycin was effective in inhibiting impaired autophagy and podocyte injury evoked by sPLA2-IB. It was found that mTOR phosphorylation and ULK1 ser757 phosphorylation were increased, and autophagy decreased by the in stimulation of sPLA2-IB, which also led to a reduction in the adhesion and an increasing in migratory phenotype of podocytes.…”

Deubiquitinases: Modulators of Different Types of Regulated Cell Death

“…In human podocytes, USP14-mediated deubiquitination and stabilization of SPAG5 contribute to podocyte injury, a clinical predictor of diabetic nephropathy. The USP14/SPAG5-positive-regulatory axis inhibits autophagy and promotes apoptosis by activating AKT/mTOR [ 179 ]. The nickel complex NiPT, which is a proteasomal DUB inhibitor, inhibits USP14 and UCHL5 and promotes autophagy associated with the ER stress/AMPK/mTOR/S6K regulatory axis in lung cancer cells.…”