| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
Laboratory for Diabetic Nephropathy (Y.K., S.M.), SNP Research Center, The Institute of Physical and Chemical Research, Kanagawa 230-0045, Japan; and Department of Medicine, Metabolism & Endocrinology (Y.T., R.K.), School of Medicine, Juntendo University, Tokyo 113-8421, Japan
Address all correspondence and requests for reprints to: Shiro Maeda, Laboratory for Diabetic Nephropathy, SNP Research Center, The Institute of Physical and Chemical Research, 1-7-22 Suehiro-cho, Tsurumi-ku, Yokohama, Kanagawa 230-0045, Japan. E-mail: smaeda{at}src.riken.jp.
 |
ABSTRACT |
|---|
 TOP ABSTRACT INTRODUCTIONRESULTSDISCUSSIONMATERIALS AND METHODSREFERENCES |
|---|
|
INTRODUCTION |
|---|
|
TOPABSTRACTINTRODUCTIONRESULTSDISCUSSIONMATERIALS AND METHODSREFERENCES |
|---|
(PPAR-) and glucose transporter 4 (GLUT4) in adipocytes and have been considered to contribute to the pathogenesis of type 2 diabetes (9, 10). We have recently identified KLF7, ubiquitous Kruppel-like factor, on chromosome 2q32 as a new susceptibility gene to type 2 diabetes by a large-scale case-control association study focusing on the genes encoding KLF families in Japanese individuals. We also demonstrated that KLF7 was able to inhibit adipogenesis in 3T3-L1 cells (11). However, the precise mechanism by which KLF7 contributes to the pathogenesis of type 2 diabetes has not yet been elucidated. The KLF7 gene is expressed in adipocytes and various human tissues, including pancreas, liver, and skeletal muscle, which are all considered to be key organs for the pathogenesis of type 2 diabetes. In the study reported here, we examined the effects of KLF7 on the cellular functions of adipocytes, pancreatic ß-cells, skeletal muscle cells, and hepatocytes, and provide evidence that KLF7 contributes to the pathogenesis of type 2 diabetes by affecting adipogenesis and adipocytokine secretion in adipocytes and by inhibiting insulin expression and secretion in pancreatic ß-cells.
|
RESULTS |
|---|
|
TOPABSTRACTINTRODUCTIONRESULTSDISCUSSIONMATERIALS AND METHODSREFERENCES |
|---|
). We also observed the expression of KLF7 in cultured preadipocytes and matured adipocytes [3T3-L1; human preadipocyte (HPA)], insulin-secreting cell lines (HIT-T15, RIN-5F), a skeletal muscle cell line (L6), and HepG2 cells (Fig. 1B). In mouse 3T3-L1 cells, the expression of KLF7 mRNA was abundant in the cells before differentiation was induced, and markedly decreased at 6 h after induction of differentiation. After this period, the expression of KLF7 continued to increase according to the degree of differentiation (Fig. 1C). The elimination of dexamethasone or 3-isobutyl-1-methylxanthine (IBMX) from the differentiation media could significantly reduce the inhibitory effects of differentiation cocktail on the reduction of KLF7 expression, whereas the absence of insulin seemed not to affect the expression of the KLF7 (Fig. 1D). As shown in Fig. 1E, dexamethasone and IBMX seemed to have an independent effect on the suppression of the KLF7 expression, although the decrease of the KLF7 in these cells was not statistically significant. Pioglitazone also did not have any effect on the expression of KLF7 (Fig. 1E).
|
, differentiation of the human adipocytes was remarkably inhibited in the cells overexpressing KLF7 compared with control cells at 14 d after induction of differentiation. Quantification of the accumulated lipid droplets revealed that the amount of lipid droplets in the cells overexpressing KLF7 was less than 0.5% of that in the control cells (Fig. 2B). The expression of PPAR-, CCAAT/enhancer binding protein (C/EBP)
, adipocyte protein aP2 (aP2), and adipsin was significantly reduced in KLF7-overexpressing cells compared with control cells, whereas those of C/EBPß and C/EBP
were not affected by the KLF7 overexpression (Fig. 2C).
|
; 1.217 ± 0.241 and 14.206 ± 5.219 for LacZ and KLF7, respectively; P < 0.05), whereas the expression of adiponectin and leptin was significantly reduced in KLF7-overexpressing cells (adiponectin: 1.072 ± 0.112 and 0.407 ± 0.059 for LacZ and KLF7, respectively; P < 0.01; leptin: 1.158 ± 0.125 and 0.241 ± 0.012 for LacZ and KLF7, respectively; P < 0.001; Fig. 3A). The change in expression of resistin and type 1 plasminogen activator inhibitor was not statistically significant between KLF7-overexpressing cells and the control cells (Fig. 3A). The expression of PPAR- and aP2 was not different between KLF7-overexpressing and control adipocytes (Fig. 3A).
|
, the excretion of IL-6 protein into culture media was significantly increased in the KLF7-overexpressing cells compared with the control cells (2.9-fold; P < 0.01 vs. LacZ; Fig. 3B), whereas that for adiponectin or leptin protein was decreased in KLF7-overexpressing cells (adiponectin, 43.6%; leptin, 21.2%; P < 0.01 vs. LacZ; Fig. 3B).
Effects of KLF7 on Insulin Expression and Secretion
To ascertain the possible role of KLF7 in pancreatic ß-cells, we next examined the role of KLF7 in an insulin-secreting cell line (HIT-T15). HIT-T15 cells were infected with KLF7- or LacZ-encoding adenovirus vector for 1 h, and total RNA was prepared for quantitative real-time PCR 2 d after infection. As shown in Fig. 4A, the expression of the insulin gene was significantly reduced in the cells overexpressing KLF7 in a dose-dependent manner [53.5 ± 4.2, 41.5 ± 5.8, 32.3 ± 6.3, 25.5 ± 4.1: percent of control in the cells infected with KLF7 adenovirus at 1, 3, 10, and 30 multiplicity of infection (m.o.i.), respectively; P < 0.001]. The content of insulin protein was also significantly decreased in KLF7-overexpressing HIT-T15 cells (LacZ, 26.38 ng/mg protein; KLF7, 9.34 ng/mg protein; P = 0.0005; Fig. 4B).
|
, the transcriptional activity for the insulin gene promoter (–692 to +25) was remarkably suppressed by the overexpression of KLF7 (32.1 ± 2.3% of control; P < 0.0001). Subsequent analyses using various kinds of deletion mutant revealed that KLF7 could inhibit the promoter activity of all constructs, whereas KLF7 did not affect the activity of the cytomegalovirus (CMV) promoter.
We further evaluated the effects of KLF7 on glucose-stimulated insulin secretion using the HIT-T15 cells infected with adenovirus vectors encoding KLF7 or LacZ. Two days after infection, the level of glucose-stimulated insulin secreted into the culture media was determined as described in Materials and Methods. As shown in Fig. 5A, the insulin secretion from the cells overexpressing KLF7 was significantly reduced compared with that of the control cells (LacZ: 7.910 ± 1.060, 10.095 ± 0.906, 11.946 ± 0.556, 14.990 ± 1.221; KLF7: 5.141 ± 1.330, 5.057 ± 0.643, 5.439 ± 1.313, 5.131 ± 0.609; nanograms/h·mg protein at 0, 2.7, 10, 16.7 mM, respectively). The response to glucose concentrations was also suppressed in KLF7 -overexpressing cells (Fig. 5B; LacZ: 1.384 ± 0.079, 1.510 ± 0.150 and 1.895 ± 0.170-fold increase for 2.7, 10, and 16.7 mM, respectively; KLF7: 0.984 ± 0.119, 1.058 ± 0.017, and 0.998 ± 0.147-fold increase for 2.7, 10, and 16.7 mM, respectively). In contrast, KCl-induced insulin secretion was not affected by the KLF7 overexpression (Fig. 5, C and D).
|
, the mRNA expression of sulfonylurea receptor 1 (SUR1), Kir6.2, pancreatic duodenal homeobox factor 1 (PDX-1), and GLUT2 genes in KLF7-overexpressing HIT-T15 cells was significantly reduced compared with that in the control cells (SUR1: 0.993 ± 0.076 and 0.675 ± 0.032 for LacZ and KLF7, respectively, P < 0.05; Kir6.2: 1.023 ± 0.066 and 0.589 ± 0.106 for LacZ and KLF7, respectively, P < 0.05; PDX-1: 1.030 ± 0.042 and 0.472 ± 0.059 for LacZ and KLF7, respectively, P < 0.01; GLUT2: 1.067 ± 0.073 and 0.167 ± 0.079 for LacZ and KLF7, respectively; P < 0.01; Fig. 6). The change in expression of the glucokinase and NeuroD1 genes was not statistically significant between the LacZ- and KLF7-overexpressing cells (Fig. 6).
|
), whereas the change in expression of GLUT1, GLUT4, and glycogen synthase was not statistically significant between the LacZ- and KLF7-overexpressing cells. In HepG2 cells, the mRNA expression of the GLUT2 was significantly reduced in KLF7-overexpressing cells compared with that in control cells (1.148 ± 0.014 and 0.283 ± 0.021 for LacZ and KLF7, respectively; P = 0.0001; Table 1), whereas the expression of GLUT1, phosphoenol pyruvate carboxykinase, and PPAR coactivator 1 was not different between the LacZ- and KLF7-overexpressing cells.
|
|
DISCUSSION |
|---|
|
TOPABSTRACTINTRODUCTIONRESULTSDISCUSSIONMATERIALS AND METHODSREFERENCES |
|---|
We recently reported that KLF7, a member of the KLF family, is a novel candidate for conferring susceptibility to type 2 diabetes (11). We also reported that the overexpression of KLF7 resulted in a remarkable inhibition of adipogenesis in mouse 3T3-L1 cells, suggesting KLF7 may play a role in the regulation of adipocyte function. However, until now, no evidence has emerged clarifying the role of KLF7 in the pathogenesis of type 2 diabetes. In the present study, we examined the expression profile of this gene in various human tissues and several types of cultured cell lines and obtained a similar result with that reported previously (12). In 3T3-L1 cells, however, we additionally identified that the expression of KLF7 was abundant in the cells before inducing differentiation, and rapidly decreased after inducing differentiation, followed by the gradual increase according to the degree of differentiation into adipocytes. This result suggested that KLF7 might play a role in the regulation of cell functions not only in preadipocytes but also in mature adipocytes. The transient decrease of KLF7 gene expression after the induction of differentiation might be due to the direct effect of the component of the differentiation medium. To evaluate this possibility, we examined the effect of each component on the expression of the KLF7 gene. The result indicated that dexamethasone and IBMX might have some independent effects, but this result also seemed to reflect the degree of differentiation. Pioglitazone did not have any effect on adipocyte differentiation and KLF7 expression by itself in our experiment, but rats treated with pioglitazone had reduced adipocyte expression of KLF7 (our unpublished observation). Therefore, we thought KLF7 might be a physiological inhibitor of adipocyte differentiation, although the possibility for the direct effect of differentiation cocktail could not be excluded completely.
We then examined the effect of overexpression of KLF7 in human preadipocytes, and identified that adipogenesis was remarkably suppressed in KLF7-overexpressing cells, indicating that the KLF7 gene is a strong regulator of adipogenesis. We further examined the role of the KLF7 gene in matured human differentiated adipocytes. Because differentiated adipocytes have been known to be capable of secreting several cytokines, known as adipocytokines (13), we examined the expression of adipocytokines in KLF7 overexpressing human adipocytes. Our results clearly indicated that KLF7 could also regulate the expression of several adipocytokine genes in differentiated human adipocytes. Because the expression of PPAR- and aP2 was not different between KLF7-overexpressing and control human adipocytes, it is likely that the alteration of adipocytokine gene expression in KLF7-overexpressing human adipocytes was due to the direct or indirect effect of KLF7 on the regulation of these gene expressions rather than the consequence of the inhibition of further adipocyte differentiation. Because KLF7 overexpression resulted in the increase of IL-6 expression, and in the reduction of adiponectin and leptin, we suggest that the excess of KLF7 may contribute to the development of systemic insulin resistance.
In an insulin-secreting cell line (HIT-T15), we also demonstrated that the expression and glucose-induced excretion of insulin were remarkably suppressed in HIT-T15 cells overexpressing KLF7. The effect of KLF7 on insulin gene expression was likely to be due to the inhibition of transcriptional activation of the gene. The expression of PDX-1 was also decreased in KLF7 overexpressing cells, but the results using various deletion constructs, including the fragment deleting the PDX-1-binding site, suggested KLF7 could affect basal promoter activity for insulin gene transcription. It would be worthwhile to investigate the mechanism by which KLF7 is able to inhibit the glucose-induced insulin secretion from the cells. Although the content of insulin in the KLF7-overexpressing cells was remarkably decreased, and this might lead to a reduction in insulin reserves, a sufficient amount of insulin was still considered to exist because KCl-induced insulin secretion was not inhibited in the KLF7-overexpressing cells. Therefore, we suggest that KLF7 may directly affect the secretory process induced by extracellular glucose. Next, we examined the expression of genes related to glucose transport, glucose metabolism, and insulin secretion in a KLF7-overexpressing ß-cell line with quantitative real-time PCR. As a result, we found that the expression of GLUT2, SUR1, and Kir6.2 was reduced in KLF7-overexpressing cells. It has been reported that the expression of GLUT2 was remarkably reduced in glucose-unresponsive islets from different animal models of diabetes (14, 15, 16, 17, 18, 19), and mice lacking GLUT2 reportedly exhibited impaired glucose-induced insulin secretion (20). It has also been reported that the mutation of SUR1 or Kir6.2 in humans causes hyperinsulinemic hypoglycemia in infancy, and SUR1 or Kir6.2 null mice could not secrete insulin in response to glucose (21, 22). Mice introducing a loss of function mutation of Kir6.2 (G132S) were also reported to show hyperglycemia due to the disability for the secretion of insulin in response to glucose (23). These reports also demonstrated that the heterozygous subjects and heterozygous mice did not exhibit an abnormal glucose homeostasis, which suggests that complete disruption of each gene might be required for exhibition of the reported phenotype. Because the overexpression of KLF7 could not completely suppress the expression of these genes in our study, the reduction in the expression of these genes may cooperate with each other to mediate the inhibitory effect of KLF7 on glucose-induced insulin secretion in pancreatic ß-cells.
In a rat skeletal muscle cell line, we observed a significant decrease in the expression of hexokinase 2 in KLF7-overexpressing cells. It has been reported that expression and activity of hexokinase in the skeletal muscle were reduced in patients with type 2 diabetes compared with control subjects (24). Therefore, the KLF7-induced reduction of the hexokinase gene expression in skeletal muscle cells may also contribute to the impaired response to insulin.
Finally, we observed a significant decrease in the expression of GLUT2 in KLF7-overexpressing hepatocytes compared with control cells. Because it has been reported that glucose uptake was almost completely suppressed in hepatocytes of GLUT2-null mice (25), KLF7 may also participate in the impaired glucose uptake in hepatocytes through the reduction of GLUT2 expression.
From these results, it is suggested that KLF7, which has been shown to be a new candidate gene for type 2 diabetes, plays an important role in the onset and the progression of type 2 diabetes through multiple mechanisms, including an impairment of insulin biosynthesis and secretion in pancreatic ß-cells, a dysregulation of adipocytokine gene expression in adipose, a suppression of hexokinase 2 gene expression in skeletal muscle, and a suppression of GLUT2 gene expression in hepatocyte. Therefore, the inhibition of KLF7 expression and/or activity may be a target for a new therapeutic and/or preventative approach for treating type 2 diabetes, although the elucidation of the precise mechanism requires further study.
In summary, we have demonstrated that KLF7 can regulate the function of adipocytes, pancreatic ß-cells, and skeletal muscle cells and is involved in the pathogenesis of type 2 diabetes. Our present results suggest that KLF7 is a new target for drug discovery in type 2 diabetes.
|
MATERIALS AND METHODS |
|---|
|
TOPABSTRACTINTRODUCTIONRESULTSDISCUSSIONMATERIALS AND METHODSREFERENCES |
|---|
3T3-L1 Cell Culture
Mouse 3T3-L1 preadipocytes were cultured at 37 C in DMEM containing 10% fetal bovine serum, 50 IU/ml penicillin G, and 50 µg/ml streptomycin in an atmosphere of 5% CO2. To induce differentiation, confluent preadipocytes were cultured in differentiation medium (DMEM; 10% fetal bovine serum, 1 µM insulin, 1 µM dexamethasone, and 0.5 mM 3-isobutyl-1-methylxanthine) for 2 d. At the indicated number of days after inducing differentiation, total RNA was extracted and used for quantitative real-time PCR.
Construction of Adenovirus Vector Encoding Human KLF7
cDNA for human KLF7 (837 bp: GenBank accession no. NM_003709) was generated by amplification from Human Adipocyte Marathon-Ready cDNA (CLONTECH Laboratories, Inc., Palo Alto, CA) using the following primers: sense, 5'-TGA GCC AGA CAG ACT GAC AA-3'; antisense, 5'-CCT TTA GAC ACT AGC CGA TG-3'. Amplified products were separated on a 0.8% agarose gel and the desired band was purified with the MinElute Gel Extraction Kit (QIAGEN, Valencia, CA). The purified human KLF7 cDNA was subcloned into pCR2.1-TOPO vector (Invitrogen, Carlsbad, CA) and verified by direct sequencing to confirm that the obtained fragment corresponded to human KLF7.
Adenovirus vector encoding human KLF7 was prepared using the Adenovirus Expression Vector Kit (TaKaRa, Shiga, Japan) according to the manufacturer’s instructions. Briefly, human KLF7 cDNA was inserted into the pAxCAwt plasmid, which contains a CAG promoter (CMV enhancer, chicken ß-actin promoter, and part of an untranslated region of rabbit ß-globin), and the plasmid was introduced into human embryonic kidney 293 cells using the FuGENE6 transfection procedure. The adenovirus from a single plaque was expanded and purified twice by cesium chloride gradient ultracentrifugation, and dialyzed in a solution of 10% glycerol in PBS. After determination of the viral titer by a plaque assay, the viral solution was stored at –80 C until use. Control adenovirus, which carries ß-galactosidase cDNA (LacZ), was prepared using the same procedure as described above.
Preparation of Human Adipocytes and Infection
Human preadipocytes were cultured at 37 C in DMEM:HAM-F10 (1:1, vol/vol) containing 10% fetal bovine serum, 50 IU/ml penicillin G, and 50 µg/ml streptomycin in an atmosphere of 5% CO2. Cells were introduced to differentiate into adipocytes in 1:1 DMEM:HAM-F10 containing 10% fetal bovine serum, 2 µM insulin, 0.2 mM indomethacin, 1 µM dexamethasone, and 0.5 mM 3-isobutyl-1-methylxanthine. For differentiation study, cells were transduced with adenovirus vectors encoding either KLF7 or LacZ at a m.o.i. of 100 plaque-forming units/cell 48 h before the induction of differentiation, and samples were obtained at the indicated days after inducing differentiation. To determine the effect of KLF7 on adipocytokine gene expressions, human adipocytes were infected with adenovirus vectors at the indicated m.o.i. 14 d after inducing differentiation.
Oil Red O Staining
At the indicated number of days after inducing differentiation, human adipocytes were washed three times with PBS and then fixed for 1 h with 3.7% formaldehyde. Fixed cells were incubated with oil red O for 15 min at room temperature. After washing the cells four times with water, the stained lipid droplets in the cells were visualized by light microscopy. For quantification, the dye was extracted with isopropyl alcohol, and the absorbance was measured at 540 nm.
Measurement of Adipocytokines Secretion by ELISA
HPA cells were seeded in six-well plates, and confluent preadipocytes were stimulated with differentiation medium. Fourteen days after induction of differentiation, human adipocytes were infected with LacZ or KLF7 adenovirus at 100 m.o.i. overnight and cultured for 4 d. Culture medium was changed to a 500 µl volume of new medium, and the medium was collected after 24 h. The protein content of adipocytokines in the supernatants was measured by ELISA using commercially available kits according to the manufacturer’s specifications. Total protein was determined by a modified Lowry method using the DC Protein Assay (Bio-Rad Laboratories, Inc., Hercules, CA).
Insulin-Secreting Cell Culture and Infection
The insulin-secreting cell line, HIT-T15, was maintained at 37 C in RPMI 1640 medium supplemented with 10% fetal bovine serum, 50 IU/ml penicillin G, and 50 µg/ml streptomycin in an atmosphere of 5% CO2. Cells plated into 24-well tissue culture dishes (1 x 105 cells per well) were infected with adenovirus vectors encoding KLF7 or LacZ at 10 m.o.i. for 1 h.
Measurements of Insulin Secretion
Forty eight hours after infection, the cells were washed three times with HEPES-Krebs buffer containing 0.2% BSA and incubated for 2 h in HEPES-Krebs buffer containing 0.2% BSA. Subsequently, cells were incubated in HEPES-Krebs buffer containing 0.2% BSA with 0, 2.7, 10, or 16.7 mM glucose, or 100 mM KCl for 1 h at 37 C, and the incubation media were collected to measure insulin secreted from the cells. Next, the cells were treated with radioimmune precipitation assay buffer to measure intracellular insulin or total protein contents. The concentration of insulin was determined by ELISAs using commercially available kits according to the manufacturer’s specifications (MORINAGA, Yokohama, Japan). Total protein was determined by a modified Lowry method using the DC Protein Assay (Bio-Rad).
Construction of Rat Insulin Promoter and Transfection Experiments
The various fragments identical to the rat insulin 2 promoter were amplified by PCR using rat genomic DNA as a template. The primers used for the amplification are shown in Table 2. The amplified products were purified and inserted into pCR2.1-TOPO vector (Invitrogen), and the identity of the fragments was checked by direct sequencing. DNA fragments digested with MluI and XhoI were subcloned into a luciferase reporter vector (pGL3-Basic; Promega Corp., Madison, WI) at its multiple cloning site upstream of the luciferase reporter gene.
|
L6 and HepG2 Cell Culture and Infection
L6 cells and HepG2 were maintained at 37 C in DMEM supplemented with 10% fetal bovine serum (vol/vol), 50 IU/ml penicillin G, and 50 µg/ml streptomycin in an atmosphere of 5% CO2. L6 cells were differentiated in DMEM supplemented with 2% fetal bovine serum in myotubes within 7 d after seeding. HepG2 cells and differentiated L6 cells were infected with adenovirus vectors encoding KLF7 or LacZ, and 2 d after infection, total RNA was extracted for quantitative real-time PCR.
Quantitative Real-Time PCR
Total RNA was extracted from the cells using the RNeasy Mini Kit (QIAGEN, Chatsworth, CA) according to the manufacturer’s instructions, and 5 µg of total RNA was reverse transcribed with the SuperScript first-strand synthesis system (Invitrogen). Real-time PCR was carried out using the Mx3000P Multiplex Quantitative PCR system (Stratagene, La Jolla, CA). PCRs were performed in a 22-µl reaction mixture containing 1x Ex Taq buffer, 200 nM deoxynucleotide triphosphate, 800 nM primer, 0.05 U/µl Ex Taq HS polymerase, 1/20000 SYBR green (CAMBREX, Rockland, ME). The thermal profile consisted of 2 min at 50 C, 10 min at 95 C, followed by 40 cycles of 30 sec at 95 C, 30 sec at 68 C, and 30 sec at 72 C for human KLF7, phosphoenolpyruvate carboxykinase, rat glycogen synthase, and hamster insulin; 40 cycles of 30 sec at 95 C, 30 sec at 60 C, 30 sec at 72 C for human adiponectin, leptin, resistin, type 1 plasminogen activator inhibitor, IL-6, PPAR-, aP2, GLUT1, GLUT2, PPAR- coactivator 1, rat GLUT1, GLUT4, and hexokinase 2; 40 cycles of 30 sec at 95 C, 30 sec at 65 C, 30 sec at 72 C for hamster glucokinase, SUR1, Kir6.2, NeuroD1, and PDX-1; or 50 cycles of 30 sec at 95 C, 30 sec at 60 C for hamster GLUT2. The primers used for the amplification are shown in Table 2.
Statistical Analysis
Statistical analysis of the difference between the two groups was performed using Student’s unpaired t test, where P < 0.05 was considered significant.
|
ACKNOWLEDGMENTS |
|---|
|
FOOTNOTES |
|---|
All authors (Y.K., Y.T., R.K., and S.M.) have no potential conflicts of interest to declare.
First Published Online December 8, 2005
Abbreviations: aP2, Adipocyte protein aP2; C/EBP, CCAAT enhancer binding protein; CMV, cytomegalovirus; GLUT, glucose transporter; HPA, human preadipocyte; IBMX, 3-isobutyl-1-methylxanthine; KLF, Kruppel-like factor; m.o.i., multiplicity of infection; PDX1, pancreatic-duodenal homeobox factor 1; PPAR, peroxisomal proliferator-activated receptor; SUR1, sulfonylurea receptor 1.
Received for publication March 24, 2005. Accepted for publication December 1, 2005.
|
REFERENCES |
|---|
|
TOPABSTRACTINTRODUCTIONRESULTSDISCUSSIONMATERIALS AND METHODSREFERENCES |
|---|
This article has been cited by other articles:
 |
|
 |
|
  D. P Zobel, C. H Andreasen, K. S Burgdorf, E. A Andersson, A. Sandbaek, T. Lauritzen, K. Borch-Johnsen, T. Jorgensen, S. Maeda, Y. Nakamura, et al. Variation in the gene encoding Kruppel-like factor 7 influences body fat: studies of 14 818 Danes Eur. J. Endocrinol., April 1, 2009; 160(4): 603 - 609. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 S. A. Eaton, A. P. W. Funnell, N. Sue, H. Nicholas, R. C. M. Pearson, and M. Crossley A Network of Kruppel-like Factors (Klfs): Klf8 IS REPRESSED BY Klf3 AND ACTIVATED BY Klf1 IN VIVO J. Biol. Chem., October 3, 2008; 283(40): 26937 - 26947. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 S. Y. Cho, P. J. Park, H. J. Shin, Y.-K. Kim, D. W. Shin, E. S. Shin, H. H. Lee, B. G. Lee, J.-H. Baik, and T. R. Lee (-)-Catechin suppresses expression of Kruppel-like factor 7 and increases expression and secretion of adiponectin protein in 3T3-L1 cells Am J Physiol Endocrinol Metab, April 1, 2007; 292(4): E1166 - E1172. [Abstract] [Full Text] [PDF]
|
|
| |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
| Endocrinology | Endocrine Reviews | J. Clin. End. & Metab. |
| Molecular Endocrinology | Recent Prog. Horm. Res. | All Endocrine Journals |
), adeno-KLF7-infecting (
), and adeno-LacZ-infecting (
) cells. *, P < 0.05; **, P < 0.01; ***, P < 0.0001, vs. control cells.
)-overexpressing HIT-T15 cells were incubated in the media containing various concentrations of glucose (0, 2.7, 10, and 16.7 mM) for 60 min. Data were presented as mean ± SEM. *, P < 0.01 vs. control cells. B, Glucose-induced increase of insulin secretion in LacZ (