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Room-temperature ionic liquid (RTIL) has been widely investigated as a nonvolatile solvent as well as a unique liquid material because of its interesting features, e.g., negligible vapor pressure and high thermal stability. Here we report that a non-volatile polymerizable RTIL is a useful starting material for the fabrication of micro/nano-scale polymer structures with a focused-ion-beam (FIB) system operated under high-vacuum condition. Gallium-ion beam irradiation to the polymerizable 1-allyl-3-ethylimidazolium bis((trifluoromethane)sulfonyl)amide RTIL layer spread on a Si wafer induced a polymerization reaction without difficulty. What is interesting to note is that we have succeeded in provoking the polymerization reaction anywhere on the Si wafer substrate by using FIB irradiation with a raster scanning mode. By this finding, two- and three-dimensional micro/nano-scale polymer structure fabrications were possible at the resolution of 500,000 dpi. Even intricate three-dimensional micro/nano-figures with overhang and hollow moieties could be constructed at the resolution of approximately 100 nm. [ABSTRACT FROM AUTHOR]

Autophagy is a cellular recycling process induced in response to many types of stress. However, little isknown of the signaling pathways that regulate autophagy during acutekidney injury (AKI). Bcl-2/adenovirus E1B 19 kDa-interacting protein(BNIP)3 and sestrin-2 are the target proteins of hypoxia-induciblefactor (HIF)-1α and p53, respectively. The aim of this study was toinvestigate the roles of BNIP3 and sestrin-2 in oxidative stressinducedautophagy during AKI. We used rat ischemia-reperfusioninjury and cultured renal tubular (NRK-52E) cells as in vivo and invitro models of AKI, respectively. Renal ischemia-reperfusion injuryupregulated the expression of BNIP3 and sestrin-2 in the proximaltubules, as measured by immunohistochemical staining and Westernblot analysis. In vitro, NRK-52E cells exposed to hypoxia showedincreased expression of BNIP3 mRNA and protein in a HIF-1α-dependent manner. In contrast, sestrin-2 mRNA and protein expressionwere upregulated in a p53-dependent manner after exposure tooxidative stress (exogenous H2O2). NRK-52E cells stably transfectedwith a fusion protein between green fluorescent protein and light chain3 were used to investigate autophagy. Overexpression of BNIP3 orsestrin-2 in these cells induced light chain 3 expression and formationof autophagosomes. Interestingly, BNIP3-induced autophagosomeswere mainly localized to the mitochondria, suggesting that this proteinselectively induces mitophagy. These observations demonstrate thatautophagy is induced in renal tubules by at least two independentpathways involving p53-sestrin-2 and HIF-1α-BNIP3, which may beactivated by different types of stress to protect the renal tubules duringAKI. [ABSTRACT FROM AUTHOR]

Hepatocyte nuclear factor-1β (HNF-1β) is a transcription factor expressed in the kidney, liver, pancreas, and other organs. Mutations of HNF-1β cause maturity- onset diabetes of the young type 5 (MODY5). The aims of this study were to investigate the functional roles of the HNF-1β/suppressor of cytokine signaling-3 (SOCS-3) pathway in tubule damage after acute kidney injury (AKI) both in vivo and in vitro and to examine the effect of HNF-1β on renal tubule formation. To clarify the significance of the HNF-1β/SOCS-3 pathway in AKI, we used a rat ischemia/reperfusion (I/R) AKI model and cultured renal tubular cells (NRK-52E cells). Western blot analysis showed that HNF-1β and polycystic kidney disease 2 (PKD2) expressions were increased at 3-12 h and 12-24 h after I/R, respectively. The expression level of SOCS-3 was decreased at 3-48 h. Immunohistological examination revealed that expression of HNF-1β was increased in proximal tubules. Overexpression of HNF-1β resulted in decreased SOCS-3 expression, activation of signal transducer and activator of transcription 3 (STAT3) and Erk, and increased [3H]thymidine uptake in the presence of hepatocyte growth factor. Furthermore, tubule formation in three-dimensional gels was inhibited by dominant-negative HNF- 1β. Our study shows that HNF-1β is upregulated after AKI in proximal tubular cells and that HNF-1β controls cellular proliferation and tubule formation by regulating SOCS-3 expression and STAT3/ Erk activation. Therefore, the current study unravels the physiological and pathological significance of the HNF-1β pathway in AKI. [ABSTRACT FROM AUTHOR]