Background: Hypoxia regulates the transport systems expression in kidney cells. Results: Expression of SGLT1 and SGLT2 is diminished in LLC-PK 1 cells exposed to low oxygen concentrations. Conclusion: HIF-1␣ modified expression of the renal transporters SGLT1 and SGLT2 in LLC-PK 1 cells. Significance: HIF-1 regulates the expression of glucose transport in LLC-PK 1 cells, and this mechanism may be involved in the adaptation of kidney cells under reductions conditions in pO 2 .

Virus-like particles (VLPs) are being used for therapeutic developments such as vaccines and drug nanocarriers. Among these, plant virus capsids are gaining interest for the formation of VLPs because they can be safely handled and are noncytotoxic. A paradigm in virology, however, is that plant viruses cannot transfect and deliver directly their genetic material or other cargos into mammalian cells. In this work, we prepared VLPs with the CCMV capsid and the mRNA-EGFP as a cargo and reporter gene. We show, for the first time, that these plant virus-based VLPs are capable of directly transfecting different eukaryotic cell lines, without the aid of any transfecting adjuvant, and delivering their nucleic acid for translation as observed by the presence of fluorescent protein. Our results show that the CCMV capsid is a good noncytotoxic container for genome delivery into mammalian cells.

Silver nanoparticles (NNPs) are extensively used for all kinds of antimicrobial applications in medical research. Their efficacy has been demonstrated against Streptococcus mutans, which is associated with dental caries. However, their cytotoxic effects on human periodontal tissue are not completely understood.Objective: The aim of this study was to evaluate the possible toxic cellular effects of different concentrations and sizes of silver nanoparticles, less than 10 nm, 15–20 nm, and 80–100 nm, respectively, on human periodontal fibroblasts. Study design: Primary culture cells isolated from human periodontal tissue were exposed to 0–1,000 µM silver nanoparticles of each size for 24-, 72-, and 168-hour periods. Cytotoxicity was evaluated with a nonradioactive, soluble MTS/PMS assay. Results: The results demonstrated that silver nanoparticles of less than 20 nm increased cytotoxicity in human periodontal fibroblasts in a dose- and time-dependent manner. Conclusion: The 80–100-nm-sized nanoparticles did not modify the viability of human primary culture cells.

UROtsa cells have been accepted as a model to study carcinogenicity mechanisms of arsenic-associated human bladder cancer. In vitro continuous exposure to monomethylarsonous acid (MMA), leads UROtsa cells to commit to malignant transformation. In this process, NF-κβ-associated inflammatory response seems to play an important role since this transcription factor activates some minutes after cells are exposed in vitro to MMA and keeps activated during the cellular malignant transformation. It is known that a slight decrease in the protein phosphatase and tensin homologue (PTEN) gene expression is enough for some cells to become malignantly transformed. Interestingly, this tumor suppressor has been proven to be negatively regulated by NF-κβ through binding to its gene promoter. Based on these observations we propose that NF-κβ may be involved in arsenic associated carcinogenesis through the negative regulation of PTEN gene expression. Changes in PTEN expression and the binding of p50 NF-κβ subunit to PTEN promoter were evaluated in UROtsa cells exposed for 4, 12, 20, or 24 wk to 50nM MMA. Results showed that MMA induced a significant decrease in PTEN expression around 20 wk exposure to MMA,which correlated with increased binding of p50 subunit to the PTEN promoter. Consistent with these results, ChIP assays also showed a significant decrease in H3 acetylation (H3ac) but an increase in the repression marks H3k9me3 and H327me3 in PTEN promoter when compared with not treated cells. These results suggest that the activation of NF-κβ by MMA may participate in UROtsa cells malignant transformation through the negative regulation of PTEN expression involving p50 homodimers-mediated chromatin remodeling around the PTEN promoter.

Hyperpolarization-activated cationic and cyclic nucleotide-gated channels (HCN) comprise four homologous subunits (HCN1-HCN4). HCN channels are found in excitable and non-excitable tissues in mammals. We have previously shown that HCN2 may transport ammonium (NH4 (+)), besides sodium (Na(+)), in the rat distal nephron. In the present work, we identified HCN1 and HCN3 in the proximal tubule (PT) and HCN3 in the thick ascending limb of Henle (TALH) of the rat kidney. Immunoblot assays detected HCN1 (130 kDa) and HCN3 (90 KDa) and their truncated proteins C-terminal HCN1 (93 KDa) and N-terminal HCN3 (65 KDa) in enriched plasma membranes from cortex (CX) and outer medulla (OM), as well as in brush-border membrane vesicles. Immunofluorescence assays confirmed apical localization of HCN1 and HCN3 in the PT. HCN3 was also found at the basolateral membrane of TALH. We evaluated chronic changes in mineral dietary on HCN3 protein abundance. Animals were fed with three different diets: sodium-deficient (SD) diet, potassium-deficient (KD) diet, and high-potassium (HK) diet. Up-regulation of HCN3 was observed in OM by KD and in CX and OM by HK; the opposite effect occurred with the N-terminal truncated HCN3 in CX (KD) and OM (HK). SD diet did not produce any change. Since HCN channels activate with membrane hyperpolarization, our results suggest that HCN channels may play a role in the Na(+)-K(+)-ATPase activity, contributing to Na(+), K(+), and acid-base homeostasis in the rat kidney.