Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0011849 (diabetes)
 277,896 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The pancreatic beta- and alpha-cells are developmentally related to each other but reveal diverse gene expression patterns. Among the two important transcription factors for insulin gene expression, IEF1 is present both in alpha- and beta-cells, but PDX-1/IPF1/STF-1/IDX-1, a homeodomain-containing transcription factor, is present in beta-cells but not in alpha-cells. To elucidate the function of PDX-1 in the expression of beta-cell-specific genes, we established stable alphaTC1 clone 6 (alphaTC1.6)-derived transfectants expressing PDX-1 and examined the changes in the gene expression patterns in them. The exogenous expression of PDX-1 in alphaTC1.6 cells alone could induce islet amyloid polypeptide (IAPP) mRNA expression in the cells but not the expression of insulin, glucokinase, or GLUT2 gene. However, when betacellulin was added to the medium, the PDX-1-expressing alphaTC1.6 cells, but not the control alphaTC1.6 cells, came to express insulin and glucokinase mRNAs. This did not occur with other growth factors such as epidermal growth factor, transforming growth factor alpha, and insulin-like growth factor I. GLUT2 mRNA remained undetectable in the PDX-1--expressing alphaTC1.6 cells. These observations demonstrate the potency of PDX-1 for the expression of the insulin, glucokinase, and IAPP genes and suggest that certain regulatory factors, which can partially be modified by betacellulin, also contribute to the beta-cell specificity of gene expression.
Diabetes 1996 Dec
PMID:PDX-1 induces insulin and glucokinase gene expressions in alphaTC1 clone 6 cells in the presence of betacellulin. 892 72

Prolonged poor glycemic control in non-insulin-dependent diabetes mellitus patients often leads to a decline in insulin secretion from pancreatic beta cells, accompanied by a decrease in the insulin content of the cells. As a step toward elucidating the pathophysiological background of the so-called glucose toxicity to pancreatic beta cells, we induced glycation in HIT-T15 cells using a sugar with strong deoxidizing activity, D-ribose, and examined the effects on insulin gene transcription. The results of reporter gene analyses revealed that the insulin gene promoter is more sensitive to glycation than the control beta-actin gene promoter; approximately 50 and 80% of the insulin gene promoter activity was lost when the cells were kept for 3 d in the presence of 40 and 60 mM D-ribose, respectively. In agreement with this, decrease in the insulin mRNA and insulin content was observed in the glycation-induced cells. Also, gel mobility shift analyses using specific antiserum revealed decrease in the DNA-binding activity of an insulin gene transcription factor, PDX-1/IPF1/STF-1. These effects of D-ribose seemed almost irreversible but could be prevented by addition of 1 mM aminoguanidine or 10 mM N-acetylcysteine, thus suggesting that glycation and reactive oxygen species, generated through the glycation reaction, serve as mediators of the phenomena. These observations suggest that protein glycation in pancreatic beta cells, which occurs in vivo under chronic hyperglycemia, suppresses insulin gene transcription and thus can explain part of the beta cell glucose toxicity.
 ...
PMID:Glycation-dependent, reactive oxygen species-mediated suppression of the insulin gene promoter activity in HIT cells. 901 69

To study the late beta-cell-specific function of the homeodomain protein IPF1/PDX1 we have generated mice in which the Ipf1/Pdx1 gene has been disrupted specifically in beta cells. These mice develop diabetes with age, and we show that IPF1/PDX1 is required for maintaining the beta cell identity by positively regulating insulin and islet amyloid polypeptide expression and by repressing glucagon expression. We also provide evidence that IPF1/PDX1 regulates the expression of Glut2 in a dosage-dependent manner suggesting that lowered IPF1/PDX1 activity may contribute to the development of type II diabetes by causing impaired expression of both Glut2 and insulin.
 ...
PMID:beta-cell-specific inactivation of the mouse Ipf1/Pdx1 gene results in loss of the beta-cell phenotype and maturity onset diabetes. 963 77

Maturity-onset diabetes of the young (MODY) is a heterogeneous subtype of non-insulin-dependent diabetes mellitus characterised by early onset, autosomal dominant inheritance and a primary defect in insulin secretion. To date five MODY genes have been identified: hepatocyte nuclear factor-4 alpha (HNF-4alpha/MODY1/TCF14) on chromosome 20q, glucokinase (GCK/MODY2) on chromosome 7p, hepatocyte nuclear factor-1 alpha (HNF-1alpha/MODY3/TCF1) on chromosome 12q, insulin promoter factor-1 (IPF1/MODY4) on chromosome 13q and hepatocyte nuclear factor-1 beta (HNF-1beta/MODY5/TCF2) on chromosome 17cen-q. We have screened the HNF-4alpha, HNF-1alpha and HNF-1beta genes in members of 18 MODY kindreds who tested negative for glucokinase mutations. Five missense (G31D, R159W, A161T, R200W, R271W), one substitution at the splice donor site of intron 5 (IVS5nt + 2T-->A) and one deletion mutation (P379fsdelT) were found in the HNF-1alpha gene, but no MODY-associated mutations were found in the HNF-4alpha and HNF-1beta genes. Of 67 French MODY families that we have now studied, 42 (63%) have mutations in the glucokinase gene, 14 (21%) have mutations in the HNF-1alpha gene, and 11 (16%) have no mutations in the HNF-4alpha, IPF1 and HNF-1beta genes. Eleven families do not have mutations in the five known MODY genes suggesting that there is at least one additional locus that can cause MODY.
 ...
PMID:Mutation screening in 18 Caucasian families suggest the existence of other MODY genes. 975 19

Maturity-onset diabetes of the young (MODY) is a monogenic form of non-insulin-dependent diabetes mellitus (NIDDM) characterized by an early age of onset, often in childhood or adolescence and usually < 25 years of age, and autosomal dominant inheritance. Clinical characterization of patients with MODY indicates that impaired insulin secretion is the primary defect responsible for the hyperglycemia in these patients. Genetic studies have thus far identified five MODY susceptibility genes, four of which encode transcription factors; HNF (hepatocyte nuclear factor)-1 alpha, HNF-1 beta, HNF-4 alpha, and IPF1. The association of mutations in the genes for these transcription factors with early-onset familial diabetes indicates the importance of the HNF-regulatory network in determining pancreatic beta-cell function.
 ...
PMID:[Mutations in the genes of the HNF-family cause maturity-onset diabetes of the young (MODY)]. 978 Jul 31

Expression of the homeodomain transcription factor IDX1/IPF1 has been shown to be restricted to cells in the developing foregut that form the pancreatic primordium. In the adult, IDX1/IPF1 is expressed in the duodenum and pancreatic islets. The IDX1/IPF1 gene is required for pancreatic development, and in the human, heterozygous mutations have been linked to diabetes mellitus. In the present communication, we report that IDX1/IPF1 is expressed in discrete cells of the rat central nervous system during embryonic development. Using RT-PCR, IDX1/IPF1 mRNA was detected in neural precursor RC2.E10 cells, as well as in both forebrain and hindbrain of developing rats at embryonic day 15 (E15). The presence of IDX1/IPF1 protein was confirmed by Western immunoblotting. Immunohistochemical analyses of sagittal sections of E15 rats demonstrated the presence of scattered IDX1/IPF1-immunopositive cells in the forebrain. Finally, electrophoretic mobility shift assays using nuclear extracts from neural cells revealed the presence of IDX1/IPF1 bound to a putative homeodomain protein DNA-binding site present in the promoter of the glial fibrillary acidic protein gene. Our results suggest that IDX1/IPF1 may have previously unsuspected extrapancreatic functions during development of neural cells in the central nervous system.
 ...
PMID:The pancreatic homeodomain transcription factor IDX1/IPF1 is expressed in neural cells during brain development. 1043 48

Mutations in genes encoding hepatocyte nuclear factor (HNF) are responsible for three of the five subtypes of maturity-onset diabetes of the young (MODY). This observation and molecular studies indicate that the HNF network is required for normal function of pancreatic beta-cells. This suggests that transcription factors involved in this complex network are candidates for genetic defects in MODY. Because the HNF-3beta gene is implicated in this network, we screened it for mutations in 21 probands of French ancestry with clinical diagnosis of MODY and early-onset type 2 diabetes. All of the five known MODY genes, HNF-4alpha, glucokinase, HNF-1alpha, HNF-1beta, and IPF1, were previously excluded as being the cause of diabetes in these families. By direct sequencing, we identified two transitions, an A-to-G at position -213 and a C-to-T at position -63 in the promoter and exon 1, respectively, of the HNF-3beta gene. A G-to-C transversion at position +32 in the intron 1 and three transitions, C-to-T at position 291, A-to-G at position 837, and G-to-A at position 1188 in the exon 3, resulting in noncoding mutations Ala97Ala, Gly279Gly, and Gln396Gln, respectively, were also identified. The allele frequencies were not significantly different between a control group and MODY probands. Familial segregation studies and linkage analysis showed that genetic variation in the HNF-3beta gene is unlikely to be the cause of early-onset type 2 diabetes in these Caucasian families.
Diabetes 2000 Feb
PMID:Genetic variation in the hepatocyte nuclear factor-3beta gene (HNF3B) does not contribute to maturity-onset diabetes of the young in French Caucasians. 1086 49

The homeodomain transcription factor IPF1/PDX1 is required in beta-cells for efficient expression of insulin, glucose transporter 2, and prohormone convertases 1/3 and 2. Psammomys obesus, a model of diet-responsive type 2 diabetes, shows markedly depleted insulin stores when given a high-energy (HE) diet. Despite hyperglycemia, insulin mRNA levels initially remained unchanged and then decreased gradually to 15% of the basal level by 3 weeks. Moreover, insulin gene expression was not increased when isolated P. obesus islets were exposed to elevated glucose concentrations. Consistent with these observations, no functional Ipf1/Pdx1 gene product was detected in islets of newborn or adult P. obesus using immunostaining, Western blot, DNA binding, and reverse transcriptase-polymerase chain reaction analyses. Other beta-cell transcription factors (e.g., ISL-1, Nkx2.2, and Nkx6.1) were expressed in P. obesus islets, and the DNA binding activity of the insulin transcription factors RIPE3b1-Act and IEF1 was intact. Ipf1/Pdx1 gene transfer to isolated P. obesus islets normalized the defect in glucose-stimulated insulin gene expression and prevented the rapid depletion of insulin content after exposure to high glucose. Taken together, these results suggest that the inability of P. obesus islets to adapt to dietary overload, with depletion of insulin content as a consequence, results from IPF1/PDX1 deficiency. However, because not all animals become hyperglycemic on HE diet, additional factors may be important for the development of diabetes in this animal model.
Diabetes 2001 Aug
PMID:IPF1/PDX1 deficiency and beta-cell dysfunction in Psammomys obesus, an animal With type 2 diabetes. 1147 41

Mutations in the human genes encoding hepatocyte nuclear factors (HNF) 1alpha, 1beta, 4alpha, and IPF1(PDX1/IDX1/STF1) result in pancreatic beta cell dysfunction and diabetes mellitus. In hepatocytes, hnf4alpha controls the transcription of hnf1alpha, suggesting that this same interaction may operate in beta cells and thus account for the common diabetic phenotype. We show that, in pancreatic islet and exocrine cells, hnf4alpha expression unexpectedly depends on hnf1alpha. This effect is tissue-specific and mediated through direct occupation by hnf1alpha of an alternate promoter located 45.6 kb from the previously characterized hnf4alpha promoter. Hnf1alpha also exerts direct control of pancreatic-specific expression of hnf4gamma and hnf3gamma. Hnf1alpha dependence of hnf4alpha, hnf4gamma, hnf3gamma, and two previously characterized distal targets (glut2 and pklr) is established only after differentiated cells arise during pancreatic embryonic development. These studies define an unexpected hierarchical regulatory relationship between two genes involved in human monogenic diabetes in the cells, which are relevant to its pathophysiology. Furthermore, they indicate that hnf1alpha is an essential component of a transcription factor circuit whose role may be to maintain differentiated functions of pancreatic cells.
 ...
PMID:A transcription factor regulatory circuit in differentiated pancreatic cells. 1173 36

A paired homeodomain transcription factor, PAX6, is a well-known regulator of eye development, and its heterozygous mutations in humans cause congenital eye anomalies such as aniridia. Because it was recently shown that PAX6 also plays an indispensable role in islet cell development, a PAX6 gene mutation in humans may lead to a defect of the endocrine pancreas. Whereas heterozygous mutations in islet-cell transcription factors such as IPF1/IDX-1/STF-1/PDX-1 and NEUROD1/BETA2 serve as a genetic cause of diabetes or glucose intolerance, we investigated the possibility of PAX6 gene mutations being a genetic factor common to aniridia and diabetes. In five aniridia and one Peters' anomaly patients, all of the coding exons and their flanking exon-intron junctions of the PAX6 gene were surveyed for mutations. The results of direct DNA sequencing revealed three different mutations in four aniridia patients: one previously reported type of mutation and two unreported types. In agreement with polypeptide truncation and a lack of the carboxyl-terminal transactivation domain in all of the mutated PAX6 proteins, no transcriptional activity was found in the reporter gene analyses. Oral glucose tolerance tests revealed that all of the patients with a PAX6 gene mutation had glucose intolerance characterized by impaired insulin secretion. Although we did not detect a mutation within the characterized portion of the PAX6 gene in one of the five aniridia patients, diabetes was cosegregated with aniridia in her family, and a single nucleotide polymorphism in intron 9 of the PAX6 gene was correlated with the disorders, suggesting that a mutation, possibly located in an uncharacterized portion of the PAX6 gene, can explain both diabetes and aniridia in this family. In contrast, the patient with Peters' anomaly, for which a PAX6 gene mutation is a relatively rare cause, showed normal glucose tolerance (NGT) and did not show a Pax6 gene mutation. Taken together, our present observations suggest that heterozygous mutations in the PAX6 gene can induce eye anomaly and glucose intolerance in individuals harboring these mutations.
Diabetes 2002 Jan
PMID:PAX6 mutation as a genetic factor common to aniridia and glucose intolerance. 1175 45


1 2 3 4 5 6 7 8 9 Next >>