Single-Cell RNA Sequencing Reveals Heterogeneity Among Adult Mouse, Primate and Human Kidney Cells

Multiple studies have been performed to map the kidney landscape of human and rodent, along with the development of sequencing technique. Although rodent disease models have been widely applied, many disadvantages also exist. Non-human primates (NHPs) are considered as the closest experimental animals to humans and show great advantages in the construction of animal models of human disease. Therefore, a comprehensive understanding of the heterogeneity and homogeneity between human and multiple animal kidney cells is important for further establishing animal models of human renal disease. Here, we generated the first single-cell transcriptome data of normal adult cynomolgus monkey kidney using 10x Genomics scRNA-seq platform. Then, we further performed an in-depth comparison across species at the single-cell level, and our analysis indicated that the gene expression of adult primate kidney cells showed a better correlation with human kidney than mouse kidney. Furthermore, our results demonstrated that the cellular localization of GWAS-identified renal disease genes showed differences across species. The cellular localization of blood pressure associated genes in human displayed similarity to cynomolgus monkey. This study provided a reliable reference for further studies associated with renal diseases on NHPs. In addition, our results also provided a novel insight into the choice of renal disease animal model and a detailed explanation for close genetic relationship between NHPs and human at a single cell level.

Isolation of Antimalarial Agents From Indonesian Medicinal Plants: Swietenia mahagoni and Pluchea indica

Malaria is a neglected tropical disease that still demands serious efforts to tackle successfully, including the need for new antimalarial lead compounds to combat drug-resistant Plasmodium. Intensive phytochemical and pharmacological investigation into the Indonesian medicinal plants Swietenia mahagoni and Pluchea indica successfully revealed 5 constituents. Antimalarial bioassays indicated 34,5-tri- O-caffeoylquinic acid (4) to be the most active against Plasmodium falciparum 3D7 and Dd2 strains with IC50 values of 8.2 and 8.8 µM, respectively. No cytotoxicity was observed against Human Embryonic Kidney cells at a concentration of 40 µM.

Akt Inhibition as Preconditioning Treatment to Protect Kidney Cells against Anoxia

Lesions issued from the ischemia/reperfusion (I/R) stress are a major challenge in human pathophysiology. Of human organs, the kidney is highly sensitive to I/R because of its high oxygen demand and poor regenerative capacity. Previous studies have shown that targeting the hypusination pathway of eIF5A through GC7 greatly improves ischemic tolerance and can be applied successfully to kidney transplants. The protection process correlates with a metabolic shift from oxidative phosphorylation to glycolysis. Because the protein kinase B Akt is involved in ischemic protective mechanisms and glucose metabolism, we looked for a link between the effects of GC7 and Akt in proximal kidney cells exposed to anoxia or the mitotoxic myxothiazol. We found that GC7 treatment resulted in impaired Akt phosphorylation at the Ser473 and Thr308 sites, so the effects of direct Akt inhibition as a preconditioning protocol on ischemic tolerance were investigated. We evidenced that Akt inhibitors provide huge protection for kidney cells against ischemia and myxothiazol. The pro-survival effect of Akt inhibitors, which is reversible, implied a decrease in mitochondrial ROS production but was not related to metabolic changes or an antioxidant defense increase. Therefore, the inhibition of Akt can be considered as a preconditioning treatment against ischemia.

Macrophage Heterogeneity in the Intestinal Cells of Salmon: Hints From Transcriptomic and Imaging Data

The intestine has many types of cells that are present mostly in the epithelium and lamina propria. The importance of the intestinal cells for the mammalian mucosal immune system is well-established. However, there is no in-depth information about many of the intestinal cells in teleosts. In our previous study, we reported that adherent intestinal cells (AIC) predominantly express macrophage-related genes. To gather further evidence that AIC include macrophage-like cells, we compared their phagocytic activity and morphology with those of adherent head kidney cells (AKC), previously characterized as macrophage-like cells. We also compared equally abundant as well as differentially expressed mRNAs and miRNAs between AIC and AKC. AIC had lower phagocytic activity and were larger and more circular than macrophage-like AKC. RNA-Seq data revealed that there were 18309 mRNAs, with 59 miRNAs that were equally abundant between AIC and AKC. Integrative analysis of the mRNA and miRNA transcriptomes revealed macrophage heterogeneity in both AIC and AKC. In addition, analysis of AIC and AKC transcriptomes revealed functional characteristics of mucosal and systemic macrophages. Five pairs with significant negative correlations between miRNA and mRNAs were linked to macrophages and epithelial cells and their interaction could be pointing to macrophage activation and differentiation. The potential macrophage markers suggested in this study should be investigated under different immune conditions to understand the exact macrophage phenotypes.

Regucalcin ameliorates Doxorubicin-induced cytotoxicity in Cos-7 kidney cells and translocates from the nucleus to the mitochondria

Doxorubicin (DOX) is a potent anti-cancer drug, which can have unwanted side-effects such as cardiac and kidney toxicity. A detailed investigation was undertaken of the acute cytotoxic mechanisms of DOX on kidney cells, using Cos-7 cells as kidney cell model. Cos-7 cells were exposed to DOX for a period of 24 hours over a range of concentrations and the LC50 was determined to be 7µM. Further investigations showed that cell death was mainly via apoptosis involving Ca2+ and caspase 9, in addition to autophagy. Regucalcin (RGN), a cytoprotective protein found mainly in liver and kidney tissues, was overexpressed in Cos-7 cells and shown to protect against DOX-induced cell death. Subcellular localization studies in Cos-7 cells showed RGN to be strongly correlated with the nucleus. However, upon treatment with DOX for 4 hours, which induced membrane blebbing in some cells, the localization appeared to be correlated more with the mitochondria in these cells. It is yet to be determined whether this translocation is part of the cytoprotective mechanism or a consequence of chemically-induced cell stress.

PP2A phosphatase inhibition is anti-fibrotic through Ser77 phosphorylation-mediated ARNT/ARNT homodimer formation

Aryl hydrocarbon receptor nuclear translocator (ARNT) mediates anti-fibrotic activity in kidney and liver through induction of ALK3-receptor expression and subsequently increased Smad1/5/8 signaling. While expression of ARNT can be pharmacologically induced by sub-immunosuppressive doses of FK506 or by GPI1046, its anti-fibrotic activity is only realized when ARNT-ARNT homodimers form, as opposed to formation of ARNT-AHR or ARNT-HIF1α heterodimers. Mechanisms underlying ARNTs dimerization decision to specifically form ARNT–ARNT homodimers and possible cues to specifically induce ARNT homodimerization have been previously unknown. Here, we demonstrate that phosphorylation of the Ser77 residue is critical for ARNT–ARNT homodimer formation and stabilization. We further demonstrate that inhibition of PP2A phosphatase activity by LB100 enhances ARNT–ARNT homodimers both in vivo and in vitro (mouse tubular epithelial cells and human embryonic kidney cells). In murine models of kidney fibrosis, and also of liver fibrosis, combinations of FK506 or GPI1046 (to induce ARNT expression) with LB100 (to enhance ARNT homodimerization) elicit additive anti-fibrotic activities. Our study provides additional evidence for the anti-fibrotic activity of ARNT–ARNT homodimers and reveals Ser77 phosphorylation as a novel pharmacological target to realize the therapeutic potential of increased ARNT transactivation activity.