The loss of podocyte (PD) molecular phenotype is an important feature of diabetic podocytopathy. We hypothesized that high glucose (HG) induces dedifferentiation in differentiated podocytes (DPDs) through alterations in the apolipoprotein (APO) L1-microRNA (miR) 193a axis. HG-induced DPD dedifferentiation manifested in the form of downregulation of Wilms' tumor 1 (WT1) and upregulation of paired box 2 (PAX2) expression. WT1-silenced DPDs displayed enhanced expression of PAX2. Immunoprecipitation of DPD cellular lysates with anti-WT1 antibody revealed formation of WT1 repressor complexes containing Polycomb group proteins, enhancer of zeste homolog 2, menin, and DNA methyltransferase (DNMT1), whereas silencing of either WT1 or DNMT1 disrupted this complex with enhanced expression of PAX2. HG-induced DPD dedifferentiation was associated with a higher expression of miR193a, whereas inhibition of miR193a prevented DPD dedifferentiation in HG milieu. HG downregulated DPD expression of APOL1. miR193a-overexpressing DPDs displayed downregulation of APOL1 and enhanced expression of dedifferentiating markers; conversely, silencing of miR193a enhanced the expression of APOL1 and preserved DPD phenotype. Moreover, stably APOL1G0-overexpressing DPDs displayed the enhanced expression of WT1 but attenuated expression of miR193a; nonetheless, silencing of APOL1 reversed these effects. Since silencing of APOL1 enhanced miR193a expression as well as dedifferentiation in DPDs, it appears that downregulation of APOL1 contributed to dedifferentiation of DPDs through enhanced miR193a expression in HG milieu. Vitamin D receptor agonist downregulated miR193a, upregulated APOL1 expression, and prevented dedifferentiation of DPDs in HG milieu. These findings suggest that modulation of the APOL1-miR193a axis carries a potential to preserve DPD molecular phenotype in HG milieu.

Human parietal epithelial cells (PECs) are progenitor cells that sustain podocyte homeostasis. We hypothesized that the lack of apolipoprotein (APO) L1 ensures the PEC phenotype, but its induction initiates PEC transition (expression of podocyte markers). APOL1 expression and down-regulation of miR193a coincided with the expression of podocyte markers during the transition. The induction of APOL1 also stimulated transition markers in human embryonic kidney cells (cells with undetectable APOL1 protein expression). APOL1 silencing in PECs up-regulated miR193a expression, suggesting the possibility of a reciprocal feedback relationship between APOL1 and miR193a. HIV, interferon-γ, and vitamin D receptor agonist down-regulated miR193a expression and induced APOL1 expression along with transition markers in PECs. Luciferase assay suggested a putative interaction between miR193a and APOL1. Since silencing of APOL1 attenuated HIV-, vitamin D receptor agonist-, miR193a inhibitor-, and interferon-γ-induced expression of transition markers, APOL1 appears to be a critical functional constituent of the miR193a- APOL1 axis in PECs. This notion was confirmed by further enhanced expression of PEC markers in APOL1 mRNA-silenced PECs. In vivo studies, glomeruli in patients with HIV, and HIV/APOL1 transgenic mice had foci of PECs expressing synaptopodin, a transition marker. APOL1 likely regulates PEC molecular phenotype through modulation of miR193a expression, and APOL1 and miR193a share a reciprocal feedback relationship.

APOL1-miR193a axis participates in the preservation of molecular phenotype of differentiated podocytes (DPDs). We examined the hypothesis that APOL1 (G0) preserves, but APOL1 risk alleles (G1 and G2) disrupt APOL1-miR193a axis in DPDs. DPDG0s displayed down-regulation of miR193a, but upregulation of nephrin expression. DPDG1s/G2s exhibited an increase in miR193a and down-regulation of the expression of adherens complex’s constituents (CD2AP, nephrin, and dendrin). DPDG0s showed decreased Cathepsin L, enhanced dynamin expressions, and the intact actin cytoskeleton. On the contrary, DPDG1s/G2s displayed an increase in Cathepsin L, but down-regulation of dynamin expressions and disorganization of the actin cytoskeleton. APOL1 silencing enhanced miR193a and Cathepsin L, but down-regulated dynamin expressions. DPDG1s/G2s displayed nuclear import of dendrin, indicating an occurrence of destabilization of adherens complexes in APOL1 risk milieu. These findings suggest that DPDG1s and DPDG2s developed disorganized actin cytoskeleton as a consequence of disrupted APOL1-miR193a axis. Interestingly, docking and co-labeling studies suggested an interaction between APOL1 and CD2AP. APOL1 G1 / G1 and APOL1 G1 / G2 transgenic mice displayed nuclear import of dendrin indicating destabilization of adherens complexes in podocytes; moreover, these mice showed a four-fold increase in urinary albumin to creatinine ratio and development of focal segmental glomerular lesions.

Background: Currently, no large, nationwide studies have been conducted to analyze the demographic factors, underlying comorbidities, clinical outcomes, and health care utilization in rhabdomyolysis patients with and without acute kidney injury (AKI). Methods: We queried the National Inpatient Sample of Healthcare Cost and Utilization Project (HCUP) with patients with rhabdomyolysis from 2016 to 2018. The chi-squared test was used to compare categorical variables, and the adjusted Wald test was employed to compare quantitative variables. The logistic regression model was applied to calculate adjusted odds ratios (ORs) with 95% confidence intervals (95% CIs) to estimate the impact of AKI on outcomes in patients with rhabdomyolysis. Results: Among 111,085 rhabdomyolysis-related hospitalizations, a higher prevalence of AKI was noticed in older patients (mean age ± SD, 58.2 ± 21.6 vs. 53.8 ± 22.2), Medicare insurance (48.5% vs. 43.2%,), and patients with a higher Charlson Comorbidity Index score (CCI 3–5, 15.1% vs. 5.5%). AKI was found to be independently associated with higher mortality (adjusted odds ratio [aOR].3.33, 95% CI 2.33–4.75), longer hospital stays (adjusted difference 1.17 days, 95% CI: 1.00−1.34), and higher cost of hospital stay (adjusted difference $11,315.05, 95% CI: $9493.02–$13,137.07). Conclusions: AKI in patients hospitalized with rhabdomyolysis is related to adverse clinical outcomes and significant economic and survival burden.

. CC-BY-ND 4.0 International license peer-reviewed) is the author/funder. It is made available under a The copyright holder for this preprint (which was not . http://dx.doi.org/10.1101/259267 doi: bioRxiv preprint first posted online Feb. 4, 2018; 3 APOL1 (G0) is a minor component of circulating lipid-rich trypanolytic multiprotein complexes in certain primate species including humans (1). It is expressed in liver, pancreas, kidney, brain, macrophages, and endothelial cells (1). Approximately 34% of African Americans carry one of the two risk variants (G1 and G2) and 13% have both variants (2, 3). Increased expression of G1 and G2 risk variant APOL1, has been shown to induce cellular injury, including podocytes (PDs), both in vitro and in vivo (4-13).Parietal epithelial cells (PECs) and PDs are derived from the same mesenchymal cells during embryogenesis (14-16); however, the expression level of miR193a determines the net phenotype-PECs vs. PDs-in these cells (17). We have recently demonstrated that APOL1-miR193a axis preserves podocyte molecular phenotype in adverse milieus (18). We now hypothesize that APOL1 and miR193a forms a reciprocally linked feedback loop to regulate PECs' phenotype in humans. In this loop, lack of APOL1 assures PECs' phenotype while its presence initiates their transition to PDs. APOL1 and miR193a are reciprocally linked with a feedback loop in PECsPECs have not been shown to display expression of APOL1 both in vitro and in vivo studies (1,19). To examine the expression of APOL1, lysates of cultured PECs, differentiated PDs and HepG2 (positive control) and HEKs (negative control) were probed for APOL1 and GAPDH. HepG2s and PDs displayed robust expression of APOL1, but PECs and HEKs did not display any expression of APOL1 protein (Fig. 1A).. CC-BY-ND 4.0 International license peer-reviewed) is the author/funder. It is made available under a The copyright holder for this preprint (which was not . http://dx.doi.org/10.1101/259267 doi: bioRxiv preprint first posted online Feb. 4, 2018; 4 Since APOL1 is expressed by PDs (1, 4, 19), we asked whether PECs transiting to PDs' phenotype would also display APOL1. PECs were incubated in media for different time intervals followed by RNA and protein extractions. Protein blots were probed for APOL1 and GAPDH. PECs did not show expression of APOL1 protein on day 0, however, APOL1 expression emerged on day 4 and increased further during transition (Fig.1B). RNAs were assayed for miR193a and cDNAs were amplified with an APOL1 specific primer. APOL1 mRNA expression increased (Fig. 1C) but miR193a levels decreased (Fig. 1D) during transition.To evaluate a possible causal relationship, PECs were transfected with either scrambled or APOL1 siRNAs. cDNAs were amplified for APOL1 and RNAs were quantified for miR193. Down regulation of APOL1 mRNA (Lower panel, Fig. 1E) was associated with an up regulation of miR193a (Upper panel, Fig. 1E). These results suggest that PECs have a functional APOL1 protein which is not detectable by available tools; nonethele...