OBJECTIVETo evaluate the effect of JAK/STAT signaling pathway activation on the transdifferentiation and secretion of transforming growth factor-beta1 (TGF-beta1) induced by high glucose in renal proximal tubular epithelial cells.

METHODSHuman kidney cells (HKC) were cultured and then divided into four groups: low glucose (LG) group, high glucose (HG) group, high mannitol (LG + M) group, and HG + AG490 group. Immunoprecipitation and Western blot analysis were used to determine the expression of tryosine phosphorylated Janus kinase 2 ( p-JAK2). The protein expressions of STAT1, STAT3, p-STAT1, and p-STAT3 and the expressions of alpha-SMA and E-Cadherin were observed by Western blot. The contents of TGF-B1, fibronectin and type I collagen in the supernatants of the cultured HKC were detected by enzyme-linked immunosorbent assay (ELISA). The expression of TGF-beta1 mRNA was measured by reverse transcription and polymerase chain reaction (RT-PCR).

RESULTSCompared with LG group, the expressions of JAK2, p-STAT1, p-STAT3, and TGF-beta1, mRNA were significantly increased in HG group from 6 to 72 hours. Meanwhile, the contents of TGF-beta1 and collagen I in the supernatants and the expression of alpha-SMA increased and the expression of E-Cadherin decreased. The expressions of JAK2, p-STAT1, p-STAT3, and TGF-beta mRNA as well as the levels of TGF-beta1 and collagen I in the supernatant s in HG + AG490 group were significantly lower than in the HG group. The expressions of alpha-SMA and E-Cadherin were also decreased in HG + AG490 group.

CONCLUSIONActivation of JAK/STAT signaling pathway may be involved in the high glucose-induced transdifferentiation and overproduction of TGF-beta1, and ECM proteins in HKCs.

Cell Line ; Cell Transdifferentiation ; Epithelial Cells ; cytology ; metabolism ; Glucose ; metabolism ; pharmacology ; Humans ; Janus Kinases ; physiology ; Kidney Tubules, Proximal ; cytology ; metabolism ; STAT Transcription Factors ; physiology ; Signal Transduction ; Transforming Growth Factor beta1 ; biosynthesis ; secretion ; Urothelium ; cytology ; metabolism

AIMTo explore effects of Ginsenosides (Rb1, Rg1) on the expression of Bcl-2, Bax in the serum of kidney ischemia/reperfusion inducing apoptosis of HK-2 cells.

METHODSThe serum of rabbits with renal ischemia/reperfusion (SIR) and the control serum of rabbits (SC) were acquired and cultured with HK-2 cells. Detected apoptosis with TUNEL assay. The experiment was designed as: control group,ischemia/ reperfusion group, Rb1 blocking group and Rg1 blocking group. To detect the expression of Bcl-2, Bax with immunocytochemistry after 24 hours' cultured.

RESULTSThe expression of Bax in Rb1 blocking group and Rg1 blocking group were significantly decreased (P < 0.01), the ratios of Bcl-2/Bax were increased as compared with ischemia/reperfusion group.

CONCLUSIONRb1 and Rg1 have protective effects on apoptosis of HK-2 cells induced by serum of kidney ischemia/reperfusion.

Animals ; Apoptosis ; drug effects ; Cell Line ; Female ; Ginsenosides ; pharmacology ; Ischemia ; blood ; Kidney ; blood supply ; Kidney Tubules, Proximal ; cytology ; Male ; Proto-Oncogene Proteins c-bcl-2 ; genetics ; metabolism ; Rabbits ; Reperfusion Injury ; blood ; Serum ; physiology ; bcl-2-Associated X Protein ; genetics ; metabolism

OBJECTIVETo study the effects of core proteoglycan on the transdifferentiation of human renal tubular epithelial cell induced by transforming growth factor beta1 (TGF-beta1) in vitro.

METHODThe cultured HK-2 cells were divided into six groups: A. negative control group; B. 10 ng/ml TGF-beta1 group; C. 10 ng/ml core proteoglycan treated group; D. 100 ng/ml core proteoglycan treated group; E. 10 ng/ml TGF-beta1 + 10 ng/ml core proteoglycan group; F. 10 ng/ml TGF-beta1 + 100 ng/ml core proteoglycan group. The changes in configuration of HK-2 cells were inspected 48 hours after adding the stimulating factor. At the same time, changes in mRNA of keratin, alpha-smooth muscle actin, vimentin were analyzed.

RESULTSCompared with group A, group B showed great changes in the morphology of cells, most cells converted into spindle shape, like fibroblast; groups E and F, especially group F showed significantly reduced spindle shape cells. Compared with group A, groups C and D had no significant changes in morphology of cells Compared with 10 ng/ml TGF-beta1 group and negative control, the mRNA expression of alpha-smooth muscle actin and vimentin had significant increase, but that of keratin reduced (P < 0.05). However, after combined treatment with TGF-beta1 and core proteoglycan, alpha-smooth muscle actin and vimentin expression were reduced significantly, while expression of keratin was up-regulated. Single core proteoglycan treated group and negative control group had no dramatic differences (P > 0.05).

CONCLUSIONTGF-beta1 can induce the transdifferentiation of human renal tubular epithelial cell and core proteoglycan has some inhibitory effect on transdifferentiation of human renal tubular epithelial cell induced by TGF-beta1 in vitro.

Actins ; physiology ; Bone Morphogenetic Protein 7 ; metabolism ; Cadherins ; metabolism ; Cell Differentiation ; drug effects ; physiology ; Cell Line ; Cell Shape ; Cell Transdifferentiation ; Cells, Cultured ; Connective Tissue Growth Factor ; pharmacology ; Epithelial Cells ; cytology ; drug effects ; physiology ; Fibroblasts ; drug effects ; pathology ; Humans ; Kidney ; pathology ; Kidney Tubules ; pathology ; Kidney Tubules, Proximal ; pathology ; Proteoglycans ; chemistry ; pharmacology ; Transforming Growth Factor beta ; genetics ; pharmacology ; Transforming Growth Factor beta1 ; chemistry ; pharmacology ; Vimentin ; metabolism

The pathogenesis of chronic cyclosporine A (CsA) nephrotoxicity has not been elucidated, but apoptosis is thought to play an important role in CsA induced tubular atrophy. Recently Fas-Fas ligand system mediated apoptosis has been frequently reported in many epithelial cells as well as in T lymphocytes. We investigated the ability of CsA to induce apoptosis in cultured human proximal tubular epithelial cells and also the effect of -MSH on them. Fas, Fas ligand, and an intracellular adaptor protein, Fas-associating protein with death domain (FADD) expression, and poly-ADP ribose polymerase (PARP) cleavage were also studied. CsA induced apoptosis in cultured tubular epithelial cells demonstrated by increased number of TUNEL positive cells and it was accompanied by a significant increase in Fas mRNA and Fas ligand protein expressions. FADD and the cleavage product of PARP also increased, indicating the activation of caspase. In -MSH co-treated cells, apoptosis markedly decreased with downregulation of Fas, Fas ligand and FADD expressions and also the cleavage product of PARP. In conclusion, these data suggest that tubular cell apoptosis mediated by Fas system may play a role in tubular atrophy in chronic CsA nephrotoxicity and pretreatment of -MSH may have a some inhibitory effect on CsA induced tubular cell apoptosis.
Antigens, CD95/genetics ; Apoptosis/*drug effects ; Carrier Proteins/biosynthesis ; Caspases/physiology ; Cells, Cultured ; Cyclosporine/*toxicity ; Human ; Immunosuppressive Agents/*toxicity ; Kidney Tubules, Proximal/cytology/*drug effects/metabolism ; Membrane Glycoproteins/biosynthesis ; NAD+ ADP-Ribosyltransferase/metabolism ; RNA, Messenger/analysis ; alpha-MSH/*pharmacology

Betaig-h3 (betaig-h3) is a secretory protein composed of fasciclin I-like repeats containing sequences that allows binding of integrins and glycosaminoglycans in vivo. Expression of betaig-h3 is responsive to TGF-beta and the protein is found to be associated with extracellular matrix (ECM) molecules, implicating betaig-h3 as an ECM adhesive protein of developmental processes. We previously observed predominant expression of betaig-h3 expression in the basement membrane of proximal tubules of kidney. In this study, the physiological relevance of such localized expression of betaig-h3 was examined in the renal proximal tubular epithelial cells (RPTEC). RPTEC constitutively expressed betaig-h3 and the expression was dramatically induced by exogenous TGF-beta1 treatment. betaig-h3 and its second and fourth FAS1 domain were able to mediate RPTEC adhesion, spreading and migration. Two known alpha3beta1 integrin-interaction motifs including aspartatic acid and isoleucine residues, NKDIL and EPDIM in betaig-h3 were responsible to mediate RPTEC adhesion, spreading, and migration. By using specific antibodies against integrins, we confirmed that alpha3beta1 integrin mediates the adhesion and migration of RPTECs on betaig-h3. In addition, it also enhanced proliferation of RPTECs through NKDIL and EPDIM. These results indicate that betaig-h3 mediates adhesion, spreading, migration and proliferation of RPTECs through the interaction with alpha3beta1 integrin and is intimately involved in the maintenance and the regeneration of renal proximal tubular epithelium.
Amino Acid Motifs ; Antibodies, Blocking/immunology ; Cell Adhesion/physiology ; Cell Movement/physiology ; Cell Proliferation ; Cells, Cultured ; Epithelial Cells/drug effects ; Extracellular Matrix Proteins/chemistry/immunology/*metabolism ; Humans ; Integrin alpha3beta1/chemistry/immunology/*metabolism ; Kidney Tubules, Proximal/cytology/metabolism/*physiology ; Peptides/chemistry/metabolism ; Protein Interaction Mapping ; Research Support, Non-U.S. Gov't ; Transforming Growth Factor beta/chemistry/immunology/*metabolism/pharmacology