Project description:Chronic metabolic acidosis occurs commonly in patients with diseased kidneys and is linked with progression to renal failure. As renal function declines there is loss of nephron mass and adaptive proximal tubular hypertrophy and hypermetabolism. We have previously demonstrated in an in vitro model of chronic acidosis in porcine LLC-PK1 cells increased ammonia generation (oxidative hypermetabolism) linked with tubular cellular dysfunction and increased markers of oxidative stress. The aim of this study was to determine the effect of chronic acidosis in HK-2 cells on changes in gene and protein expression stimulated by oxidative stress. HK-2 cells were were seeded onto 6 well plates at a density of 4x104 cells/well and cultured for 72 h in growth medium (DMEM/Ham s F12 medium supplemented with 5.5 mM glucose, 2 mM L-glutamine, 5 ug/ml insulin, 5 ug/ml transferrin, 5 ng/ml sodium selenite, 0.4 ug/ml hydrocortisone, 5 ng/ml epidermal growth factor, 100 U/ml penicillin, 100 ug/ml streptomycin, and 10% FCS). The medium was then replaced by growth media buffered to pH 7.4, 7.0 or 6.7 with 12.5 mM bis-Tris and cells were cultured for further 48 h. Media were changed to serum free media (SFM) buffered by 12.5 mM bis-Tris to pH 7.4, 7.0 or 6.7 and cells were harvested and RNA isolated after 24 h. Total RNA was isolated from HK-2 cells on 3 different occasions using Tri-reagent (Sigma, UK) as recommended by the manufacturer's protocol. The RNA from the respective replicate samples were pooled together and the RNA content was measured using RiboGreen RNA Quantitation Reagent (Molecular Probes, Invitrogen, UK). The integrity of the total RNA was verified on a denaturing agarose-formaldehyde gel.
Project description:Metabolic acidosis exacerbates chronic kidney disease, in part, by stimulating renal endothelin production. To determine if acidosis alters expression of other genes, we examined the effect of exposure of MDCK cells to pH 7.4 and pH 7.0 for 24 hours on gene expression using a canine derived microarray. Exposure to this pH stress for 24 hours led to increased expression of 278 genes (2.2% of the transcriptome) by at least two fold and 60 of these (21%) were upregulated by more than 3 fold. On the other hand, 186 genes (1.5% of the transcriptome) were down regulated by at least two fold and 16 of these (9%) were down regulated by 3 fold or more. Ten percent of the genes upregulated by at least three fold encode proteins that are pro-inflammatory cytokines, including colony stimulating factor 2, chemokine ligand 7, chemokine ligand 2 0, chemokine ligand 8, and interleukin 1M-NM-1. Two others encode metallopeptidase . The most highly upregulated gene encodes a protein, lubricin, shown to be important in preventing cartilage damage and in tissue injury or repair.Upregulation of four genes were confirmed by qPCR. Housekeeping genes were not increased. There were a total of three biological replicates, each containing one control (incubated at pH 7.4) and one acidic (pH 7.0) sample, whose RNA were extracted on different dates. Microarray studies performed on these six samples were done in duplicate.
Project description:Transcriptional profiling of Helicobacter pylori comparing 26695 wild-type strain and a HP0244-deficient mutant 26695/∆HP0244::km treated at three different pH conditions (pH 7.4, pH 4.5 without urea, or pH 2.5 with 30 mM urea) for 30 min to define the HP0244 acid-responsive regulon Keywords: Genetic modification and stress response
Project description:Here we present molecular mechanisms of Korean red ginseng (KRG) on immobilization stresses Keywords: stress response Mice were divided into three groups (3 mice / group): control, stress + no treat, and stress + Korean Red Ginseng (KRG, 100 mg). Stress + KRG group were given KRG 100 mg orally for 7 days and then exposed to immobilization stress for 45 min. stress + no treat group were administrated with phosphate buffer saline (d-PBS, pH 7.4) together with IMO stress for 45 min.
Project description:Gene expression profiling of immortalized human mesenchymal stem cells with hTERT/E6/E7 transfected MSCs. hTERT may change gene expression in MSCs. Goal was to determine the gene expressions of immortalized MSCs.
Project description:Kynureninase is a member of a large family of catalytically diverse but structurally homologous pyridoxal 5'-phosphate (PLP) dependent enzymes known as the aspartate aminotransferase superfamily or alpha-family. The Homo sapiens and other eukaryotic constitutive kynureninases preferentially catalyze the hydrolytic cleavage of 3-hydroxy-l-kynurenine to produce 3-hydroxyanthranilate and l-alanine, while l-kynurenine is the substrate of many prokaryotic inducible kynureninases. The human enzyme was cloned with an N-terminal hexahistidine tag, expressed, and purified from a bacterial expression system using Ni metal ion affinity chromatography. Kinetic characterization of the recombinant enzyme reveals classic Michaelis-Menten behavior, with a Km of 28.3 +/- 1.9 microM and a specific activity of 1.75 micromol min-1 mg-1 for 3-hydroxy-dl-kynurenine. Crystals of recombinant kynureninase that diffracted to 2.0 A were obtained, and the atomic structure of the PLP-bound holoenzyme was determined by molecular replacement using the Pseudomonas fluorescens kynureninase structure (PDB entry 1qz9) as the phasing model. A structural superposition with the P. fluorescens kynureninase revealed that these two structures resemble the "open" and "closed" conformations of aspartate aminotransferase. The comparison illustrates the dynamic nature of these proteins' small domains and reveals a role for Arg-434 similar to its role in other AAT alpha-family members. Docking of 3-hydroxy-l-kynurenine into the human kynureninase active site suggests that Asn-333 and His-102 are involved in substrate binding and molecular discrimination between inducible and constitutive kynureninase substrates.
Project description:Transcriptional profiling of human mesenchymal stem cells comparing normoxic MSCs cells with hypoxic MSCs cells. Hypoxia may inhibit senescence of MSCs during expansion. Goal was to determine the effects of hypoxia on global MSCs gene expression.