DEVELOPMENTAL ORIGINS OF RENAL CONNECTING TUBULE AND COLLECTING DUCT: ROLE OF AQP2+ PROGENITOR CELLS

The connecting tubule interconnects the nephron and collecting duct, which arise from kidney mesenchyme and the ureteric bud, respectively, to generate the functional tubular networks. The collecting duct is comprised of principal cells and intercalated cells, which bear different molecular signatures and regulate sodium/water and acid/base balance, respectively. The progenitor cells of the connecting tubule and the collecting duct remain virtually unknown. We generated two Aqp2 lineage tracing mouse models. In these models, Aqp2Cre transgene drives Cre expression by the Aqp2 promoter to exclusively either inactivate histone H3 K79 methyltransferase Dot1l (Dot1lf/f Aqp2Cre) or activate RFP in Aqp2 lineage cells during development (Aqp2Cre RFP). H3 K79methylation and RFP were used as the tracing markers. Kidney sections were examined by immunofluorescence staining combined with epifluorescence and confocal microscopy. Analyses of Dot1lf/f Aqp2Cre revealed that Dot1l ablation abolished H3 K79 methylation, which occurs in both principal and intercalated cells. These results suggest that Aqp2+ progenitor cells give rise to principal cells and intercalated cells in the absence of Dot1l function. With Aqp2Cre RFP mice, we not only confirmed that derivation of intercalated cells from Aqp2+ progenitor cells is not an artifact of Dot1l deletion, but also identified the origin and molecular identities of connecting tubules. Aqp2+ progenitors contribute to renal tubular interconnection by differentiating into various types of transitional cells in the connecting tubule to form three molecularly distinct segments: RFP+Aqp2+NCC-, RFP+Aqp2-NCC-, and RFP+Aqp2-NCC+. RFP+ indicates progenitors of Aqp2+ origin. Aqp2- represents the loss of the original Aqp2+ progenitors. NCC+is the signature of distal convoluted tubule, the last segment ofnephron linking to the connecting tubule. In summary, our study 1) highlights the molecular identity and the origin of novel and distinct connecting tubule segments; and 2) reveals Aqp2+ progenitors as the origin of various cell types of connecting tubule as well as collecting duct. Therefore, our study demonstrates novel functions of Aqp2+progenitors in the origin of collectingduct and connecting tubule formation. The discovery of the Aqp2+ progenitor cells may facilitate their further molecular and functional characterization, which is critical for regenerative medicine

AF17 Facilitates Dot1a Nuclear Export and Upregulates ENaC-Mediated Na+ Transport in Renal Collecting Duct Cells

Our previous work in 293T cells and AF17-/- mice suggests that AF17 upregulates expression and activity of the epithelial Na+ channel (ENaC), possibly by relieving Dot1a-AF9-mediated repression. However, whether and how AF17 directly regulates Dot1a cellular distribution and ENaC function in renal collecting duct cells remain unaddressed. Here, we report our findings in mouse cortical collecting duct M-1 cells that overexpression of AF17 led to preferential distribution of Dot1a in the cytoplasm. This effect could be blocked by nuclear export inhibitor leptomycin B. siRNA-mediated depletion of AF17 caused nuclear accumulation of Dot1a. AF17 overexpression elicited multiple effects that are reminiscent of aldosterone action. These effects include 1) increased mRNA and protein expression of the three ENaC subunits (α, β and γ) and serum- and glucocorticoid inducible kinase 1, as revealed by real-time RT-qPCR and immunoblotting analyses; 2) impaired Dot1a-AF9 interaction and H3 K79 methylation at the αENaC promoter without affecting AF9 binding to the promoter, as evidenced by chromatin immunoprecipitation; and 3) elevated ENaC-mediated Na+ transport, as analyzed by measurement of benzamil-sensitive intracellular [Na+] and equivalent short circuit current using single-cell fluorescence imaging and an epithelial Volt-ohmmeter, respectively. Knockdown of AF17 elicited opposite effects. However, combination of AF17 overexpression or depletion with aldosterone treatment did not cause an additive effect on mRNA expression of the ENaC subunits. Taken together, we conclude that AF17 promotes Dot1a nuclear export and upregulates basal, but not aldosterone-stimulated ENaC expression, leading to an increase in ENaC-mediated Na+ transport in renal collecting duct cells

Third-order nonlinearity in Ge–Sb–Se glasses at mid-infrared wavelengths

International audienceThe optical properties of Ge–Sb–Se glasses have been extensively studied at telecom wavelengths in recent years. However, the understanding of nonlinearity in Ge–Sb–Se glasses at mid-infrared wavelengths still remains limited. In this work, a series of Ge20SbxSe80−x (x = 0, 5, 10) glasses were prepared by conventional melt–quenching method. The absorption spectra and the refractive index of glasses were recorded. The third order nonlinearity, n2, and nonlinear absorption coefficient were measured for Ge–Sb–Se glass samples at the wavelengths of 1550, 2000 and 2500 nm by Z-scan technique, respectively. With the increasing of Sb contents, the linear refractive index of glass increased. Among the three operating wavelengths, all the three glass samples have a highest n2 at 2000 nm. By using the figure of merit (FOM) to evaluate the studied three glasses, the Ge20Sb10Se70 glass shows the greatest potential for mid-IR all optical switching device

Resveratrol ameliorates necrotizing enterocolitis in neonatal rats through regulation of inflammatory and apoptotic pathways

Purpose: To determine the efficacy of resveratrol in mitigating necrotizing enterocolitis (NEC) in neonatal rats.Methods: Necrotizing enterocolitis (NEC) was induced in neonatal rats using hypoxia and hypothermia. At the completion of treatment, the intestinal tissues of the rats were isolated for evaluation of various biochemical parameters.Results: There was significant increase in the levels of proinflammatory cytokines (TNF-α, IL-6 and IL-1β) and oxidative stress markers (MDA, xanthine oxidase and nitric oxide) in intestinal tissues of NEC rats (p < 0.05). However, resveratrol treatment led to significant decrease in the levels of cytokines and oxidative stress parameters, relative to the NEC group (p < 0.05). Furthermore, Western blotting resultsshowed up-regulation in protein expressions of inflammatory cytokines in NEC rats. However, the protein expressions of inflammatory cytokines were down-regulated in the NEC rats on treatment with resveratrol. Moreover, resveratrol reversed the NEC-induced up-regulations of Bax and caspase-3, as well as NEC-mediated down-regulation of Bcl-2.Conclusion: These results demonstrate that resveratrol mitigates NEC-induced intestinal damage in neonatal rats via anti-inflammatory, anti-apoptotic and antioxidant mechanisms of action. Therefore, resveratrol is a potential therapeutic agent for NEC

Learning to Coordinate with Anyone

In open multi-agent environments, the agents may encounter unexpected teammates. Classical multi-agent learning approaches train agents that can only coordinate with seen teammates. Recent studies attempted to generate diverse teammates to enhance the generalizable coordination ability, but were restricted by pre-defined teammates. In this work, our aim is to train agents with strong coordination ability by generating teammates that fully cover the teammate policy space, so that agents can coordinate with any teammates. Since the teammate policy space is too huge to be enumerated, we find only dissimilar teammates that are incompatible with controllable agents, which highly reduces the number of teammates that need to be trained with. However, it is hard to determine the number of such incompatible teammates beforehand. We therefore introduce a continual multi-agent learning process, in which the agent learns to coordinate with different teammates until no more incompatible teammates can be found. The above idea is implemented in the proposed Macop (Multi-agent compatible policy learning) algorithm. We conduct experiments in 8 scenarios from 4 environments that have distinct coordination patterns. Experiments show that Macop generates training teammates with much lower compatibility than previous methods. As a result, in all scenarios Macop achieves the best overall coordination ability while never significantly worse than the baselines, showing strong generalization ability

Segmentation of kidney and kidney tumor by cascaded fusion FCNs with soft-boundary regression

To produce reliable kidney and kidney tumor semantic segmentation, we proposed a two-stage method to automatically segment kidney and tumor. Specifically, in the first stage, to crop input into a small region, we train a small network to locate kidney and tumor with down-sampled image. In second stage, we train three types of networks to segment kidney, tumor, kidney and tumor respectively. Then we combine these networks together with ensemble method to produce reliable kidney and tumor segmentation. Our method can achieve an overall approximate score of 85.1% in DSC in Kits19 Challenge, with 96.9% for kidney and 73.3% for kidney tumor

Anti-proteinuric effect of sulodexide in adriamycin-induced nephropathy rats

This study investigated the anti-proteinuric effect of sulodexide in rats with adriamycin (ADR) nephropathy. A total of 40 healthy male Sprague-Dawley (SD) rats were randomly assigned to four groups: normal control group (Control-group), ADR control group (ADR-group), sulodexide treatment group (SUL-group), and losartan treatment group (LOS-group). The ADR-induced rat models were established by injecting two different doses of ADR (4 and 3.5 mg/kg) into the caudal vein of rat for two consecutive weeks. After that, SUL-group and LOS-group were respectively treated with sulodexide (10 mg/kg/day) and losartan (10 mg/kg/day) for an additional 4 weeks period. Samples of 24-hour urine were harvested at 3, 4, 5, and 6 weeks after the model establishment. The pathological change in renal tissues was observed by light microscopy, the function of liver and kidney were assayed at week 6th . The results showed that the urinary excretion of protein progressively increased in ADR-group, and accompanied with severe nephrotic syndrome such as massive albuminuria, proteinuria, and hyperlipidemia. Sulodexide effectively reduced the 24-hour urinary protein excretion of ADR-induced nephropathy rats, preventing focal segmental glomerulosclerosis. There was no significant difference between LOS-group and SULgroup for reducing urinary protein excretion (P < 0.05). Sulodexide alleviated ADR-induced nephrotoxicity as good as losartan in a short period of treatment.Colegio de Farmacéuticos de la Provincia de Buenos Aire