Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:2.7.7.49 (reverse transcriptase)
 31,746 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The aim of this study was to investigate whether mutations in hepatocyte nuclear factor (HNF)-4gamma, a transcription factor homologous to HNF-4alpha, contribute to the etiology of early-onset type 2 diabetes. Linkage between diabetes and two polymorphic markers at the HNF-4gamma locus (D8S286 and D8S548) was evaluated in 32 multigenerational families with early-onset autosomal-dominant type 2 diabetes unlinked to known maturity-onset diabetes of the young genes. Total logarithm of odds (LOD) scores were strongly negative (-50.3 at D8S286 and -46.2 at D8S548), but linkage could not be excluded in 15 families having LOD scores >-2.0. To screen these pedigrees for HNF-4gamma mutations, the gene structure was defined. Because reverse transcriptase-polymerase chain reaction experiments indicated that the first 1,674 bp of the published cDNA sequence (3,248 bp) were a cloning artifact, the correct cDNA sequence was determined by 5' rapid amplification of cDNA ends (RACE) and primer extension assay. Based on the new cDNA sequence (1,731 bp), 11 exons were found. After screening the 5' flanking region and all coding exons for mutations, we identified several polymorphisms, one of which affected the amino acid sequence (M190I). However, no mutations segregating with diabetes could be found in these families. We conclude that genetic variability in the HNF-4gamma gene is unlikely to play a major role in the etiology of early-onset autosomal-dominant type 2 diabetes.
Diabetes 1999 Oct
PMID:Hepatocyte nuclear factor-4gamma: cDNA sequence, gene organization, and mutation screening in early-onset autosomal-dominant type 2 diabetes. 1051 80

Protease inhibitor treatment has dramatically improved rates of morbidity and mortality in HIV-infected patients. However, it has recently been shown that this medication is associated with long-term side effects characterized by metabolic, clinical and biological alterations. These modifications have been described in patients treated with highly active antiretroviral therapy (HAART), including nucleoside analogue reverse transcriptase inhibitors (NRTI) and generally (but not always) protease inhibitors (PI). Clinical alterations are characterised by a body fat redistribution syndrome or lipodystrophy, with peripheral lipoatrophy and/or central fat accumulation. They are often associated with biological alterations, i.e. insulin resistance, hyperglycaemia and dyslipidaemia, which can also be observed alone. The pathophysiology of these alterations is presently unknown. The deleterious effect of PI on adipose tissue could be direct or indirect, and is probably modulated by genetic or environmental factors. NRTI could also be involved because of their mitochondrial toxicity. The purpose of the treatment is to control metabolic disturbances in order to prevent immediate complications such as acute pancreatitis and limit possible cardiovascular and diabetic complications at longer term. Studies are in progress to evaluate the possibility of therapeutic alternatives to PI when major metabolic disturbances are present.
Diabetes Metab 1999 Nov
PMID:Adverse metabolic disorders during highly active antiretroviral treatments (HAART) of HIV disease. 1059 60

Highly active antiretroviral therapy (HAART) for human immunodeficiency virus-1 (HIV-1) and prophylactic therapy for opportunistic infections have increased survival. Adverse effects of HAART include lipid profile alterations, diabetes mellitus, and fat redistribution. These metabolic and physical changes are called the HIV-associated lipodystrophy syndrome. A link to protease inhibitors has been suggested, and more recently to nucleoside reverse transcriptase inhibitors and factors related to duration of HIV-1 infection itself.
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PMID:HIV-associated lipodystrophy syndrome. 1064 72

Nonobese diabetic mice develop type 1 diabetes in an age-related and gender-dependent manner. Th1 (IFN-gamma and TNF-beta) and Th2 (IL-4 and IL-10) cytokine mRNA expression was analyzed in pancreatic islets isolated from female NOD mice with a high incidence of diabetes and male NOD mice with a low incidence of diabetes. The levels were measured at 5 time points from the onset of insulitis until the development of overt diabetes, using a semiquantitative reverse transcriptase PCR (RT-PCR) assay. IFN-gamma mRNA levels were significantly higher in the islets obtained from females than those of males, from 10 weeks of age. TNF-beta mRNA was expressed in both females and males between 5 and 15 weeks of age. However, TNF-beta mRNA levels were decreased in males at 20 weeks of age. In contrast, IL-4 mRNA levels were lower in females than in males. These results suggest that islet beta-cell destruction and diabetes in female NOD mice correlates with IFN-gamma and TNF-beta production in the islets, and that male NOD mice may be protected from autoimmune beta-cell destruction by down-regulation of these cytokines. Furthermore, our findings also suggest that insulitis and beta-cell destruction are independently regulated: TNF-beta is more important in forming and maintaining the insulitis, while IFN-gamma has a more important role in beta-cell destruction.
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PMID:Analysis of cytokine mRNA expression in pancreatic islets of nonobese diabetic mice. 1068 43

The activation of the interferon (IFN)-alpha system and its relationship with coxsackievirus B (CVB) infection has been analyzed in 56 patients with insulin-dependent diabetes mellitus (IDDM; 25 children and 31 adults). Elevated levels of IFN-alpha were found in plasma of 70% of patients (39/56), and a positive detection of IFN-alpha mRNA in blood cells by reverse transcriptase-polymerase chain reaction (RT-PCR) was observed in 75% of patients (42/56). Enterovirus (EV) RNA assayed by seminested RT-PCR was detected in the blood of 50% of IFN-alpha-positive patients but not in any IFN-alpha-negative patients. The results of genotype analysis of amplified EV RNA sequences (5 CVB2, 8 CVB3, and 8 CVB4) were concordant with the results of CVB-neutralization tests. The comparison between IFN-alpha, EV RNA, and serology suggested that the proportion of CVB infection associated with IFN-alpha positivity might be higher than is predicted from the investigation of EV RNA. Together, the results suggest that, in a majority of cases, a CVB infection is associated with clinical IDDM.
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PMID:Increased level of interferon-alpha in blood of patients with insulin-dependent diabetes mellitus: relationship with coxsackievirus B infection. 1083 72

Little is known about the mechanisms involved in the preferential channeling of different fuels to fat and how the target tissue participates in this process. Dietary fatty acids have been shown to act as signaling molecules that bind and activate a new class of nuclear receptors, the peroxisome proliferator-activated receptors (PPARs). PPAR-gamma is particularly interesting because it may have the potential to link particular fatty acids with a program of gene expression involved in lipid storage and metabolism. We investigated whether a nutrient-sensing pathway is activated by an increased availability of lipid fuels in nine normal weight male volunteers. Using reverse transcriptase-polymerase chain reaction analysis, the mRNA expression of fatty acid translocase (FAT)/CD36, PPAR-gamma2, leptin, uncoupling protein (UCP)-2 and UCP-3, and tumor necrosis factor (TNF)-alpha was investigated in gluteal subcutaneous fat biopsies before and after 5 h infusions of saline or Intralipid (Pharmacia and Upjohn, Milan, Italy) plus heparin, which does not modify insulinemia. Marked increases in FAT/CD36 (724+/-18%; P < 0.05), PPAR-gamma2 (200+/-8%; P < 0.05), leptin (110+/-13%; P < 0.05), UCP-2 (120+/-7%; P < 0.05), UCP-3 (80+/-5%; P < 0.05), and TNF-alpha mRNA (130+/-12%; P < 0.05) were observed in comparison with pretreatment levels, whereas there was no change after saline infusion. These data suggest that the in vivo gene expression of FAT/CD36, PPAR-gamma2, leptin, UCP-2, UCP-3, and TNF-alpha in subcutaneous adipose tissue is regulated by circulating lipids independent of insulin and that prolonged hyperlipidemia may therefore contribute to increased fat metabolism and storage as a result of the increased expression of these proteins.
Diabetes 2000 Mar
PMID:Induction of fatty acid translocase/CD36, peroxisome proliferator-activated receptor-gamma2, leptin, uncoupling proteins 2 and 3, and tumor necrosis factor-alpha gene expression in human subcutaneous fat by lipid infusion. 1086 51

Expression of muscarinic receptors in rat islets, RINm5F cells, and INS-1 cells was established by reverse transcriptase-polymerase chain reaction (RT-PCR) and quantified by RNase protection. Both methods indicated that m3 and m1 receptors were expressed approximately equally in the various cellular preparations and to a much greater extent than the m5 subtype. However, the cell lines, especially RINm5F cells, expressed less of a given receptor subtype than did islets. Immunohistochemistry indicated that m3 receptors were expressed throughout the islet core. Binding studies using the radiolabeled muscarinic receptor antagonist QNB demonstrated a maximal binding capacity of INS-1 cells of 23.0+/-2.9 fmol/mg protein. Functional analyses were undertaken using INS-1 cells stably transfected with either m1 or m3 receptor cDNAs. Overexpression of either receptor did not affect basal responses but markedly enhanced maximal responses to the muscarinic receptor agonist carbachol. Although maximal hydrolysis of phosphatidylinositol 4,5-bisphosphate (Ptd InsP2) was twofold greater in m1-transfectants as compared with m3-transfectants, cell lines overexpressing either receptor gave essentially equivalent secretory responses to a full range of carbachol doses. The results demonstrate that both m1 and m3 muscarinic receptors are well expressed in pancreatic beta-cells, functionally linked to signaling pathways, and capable of initiating insulin secretion with equal potencies.
Diabetes 2000 Mar
PMID:Quantitative and functional characterization of muscarinic receptor subtypes in insulin-secreting cell lines and rat pancreatic islets. 1086 60

Diabetic glomerulosclerosis is defined by increased glomerular extracellular matrix (ECM) that is mainly synthesized by mesangial cells that underwent an activation mediated by cytokines and growth factors from various cellular origins. In this study, we tested whether macrophages could infiltrate the glomeruli and influence ECM synthesis in experimental diabetes. To test our hypothesis, we initially studied the dynamics of glomerular macrophage recruitment in streptozotocin-induced diabetic rats at days 1, 2, 4, 8, 15, and 30 by using quantitative reverse transcriptase-polymerase chain reaction (RT-PCR) on isolated glomeruli and immunohistochemistry and morphometry. We then assessed the role of macrophages on the basis of the pharmacological modulation of their recruitment by insulin or ACE inhibitor treatments and by X-irradiation-induced macrophage depletion at days 8 and 30. Macrophages were recruited within the glomeruli at the very early phase of hyperglycemia by using RT-PCR CD14 detection from day 2 and by using ED1 immunohistochemistry from day 8. This glomerular macrophage infiltration was associated with an increase in alpha1-chain type IV collagen mRNA. In parallel, the diabetic glomeruli became hypertrophic with an increase in the mesangial area. Macrophage recruitment was preceded by or associated with an increased glomerular expression of vascular cell adhesion molecule 1, intracellular adhesion molecule 1, and monocyte chemoattractant protein 1, which contributes to monocyte diapedesis. Glomerular interleukin-1beta mRNA synthesis was also enhanced as early as day 1 and could be involved in the increase in ECM and adhesion molecule gene expressions. Insulin treatment and irradiation-induced macrophage depletion completely prevented the glomerular macrophage recruitment and decreased alpha1-chain type IV collagen mRNA and mesangial area in diabetic rats, whereas ACE inhibitor treatment had an incomplete effect. It can be concluded that in the streptozotocin model, hyperglycemia is followed by an early macrophage recruitment that contributes to the molecular and structural events that could lead to glomerulosclerosis. Therefore, besides direct stimulation of mesangial cells by hyperglycemia, macrophages recruited in the glomeruli during the early phase of hyperglycemia could secondarily act on mesangial cells.
Diabetes 2000 Mar
PMID:Early glomerular macrophage recruitment in streptozotocin-induced diabetic rats. 1086 70

Leptin is mainly produced in white adipose tissue and acts both at distant sites and locally at the tissue from which it originates. The cellular and subcellular localization of leptin and its receptor (Ob-receptor [Ob-R]) and their relationship to various stages of fat cell maturation have not been characterized as yet. Therefore, we analyzed leptin and Ob-R by using reverse transcriptase-polymerase chain reaction, immunohistochemistry, and ultrastructural immunogold labeling in human white adipose tissue and in human adipocyte cell cultures at early and late stages of differentiation. Both leptin and its receptor were present in mature unilocular fat cells. The thin cytoplasmic rim of the adipocytes exhibited the strongest expression of both leptin and Ob-R. At early stages of differentiating human adipocytes, leptin was mainly expressed in multilocular preadipocytes, whereas the Ob-R was found predominantly on fibroblast-like cells. Other cellular components of human white adipose tissue were characterized by anti-CD31 for endothelial cells, anti-CD68 for macrophages, and antibodies specifically labeling B-cells and T-cells. In addition to fat cells, endothelial cells were immunopositive for the full-length leptin receptor. On the ultrastructural level, leptin was mainly found attached to cellular membranes and in small alveolate vesicle-like structures in the cytoplasm of adipocytes. Leptin was also present on the cell membranes of endothelial cells and macrophages. We conclude that the expression of the Ob-R in human white adipose tissue is not restricted to adipocytes but is present in resident endothelial and immune cells. Ultrastructural localization studies revealed an association of leptin with cell membranes and small vesicles. The cellular and subcellular distribution of leptin and its receptor suggests an important autocrine and paracrine role for leptin in human adipose tissue.
Diabetes 2000 Apr
PMID:Immunohistochemical and ultrastructural localization of leptin and leptin receptor in human white adipose tissue and differentiating human adipose cells in primary culture. 1087 Nov 89

Prolonged exposure of rodent beta-cells to combinations of cytokines induces the inducible form of nitric oxide synthase (iNOS) expression and Fas expression, nitric oxide (NO) production, and cell death. It also induces the expression of potential "defense" genes, such as manganese superoxide dismutase (MnSOD) and heat shock protein (hsp) 70. NO is a radical with multifaceted actions. Recent studies have shown that NO, in addition to having cytotoxic actions, may regulate gene transcription. It remains unclear whether NO mediates cytokine-induced gene expression and subsequent beta-cell death. Previous studies using NO synthase blockers yielded conflicting results, which may be due to nonspecific effects of these agents. In this study, we examined the effects of cytokines on gene expression, determined by reverse transcriptase-polymerase chain reaction (RT-PCR), and viability, determined by nuclear dyes, of pancreatic islets or fluorescence-activated cell sorter (FACS)-purified beta-cells isolated from iNOS knockout mice (iNOS-/-, background C57BL/6x129SvEv) or their respective controls (C57BL/6x129SvEv). The combination of cytokines used was interleukin-1beta (50 U/ml) plus gamma-interferon (1,000 U/ml) plus tumor necrosis factor-alpha (1,000 U/ml). The lack of cytokine-induced iNOS activity in the iNOS-/- islet cells was confirmed by RT-PCR and nitrite determination. Cytokines induced a >3-fold increase in Fas and MnSOD mRNA expression in wild-type (WT) and iNOS-/- islets. On the other hand, hsp 70 was induced in WT but not in iNOS-/- islets. Prolonged (6-9 days) exposure of WT islets to cytokines leads to an 80-90% decrease in islet cell viability, whereas viability decreased by only 10-30% in iNOS-/- islet cells. To determine the mode of cytokine-induced cell death, FACS-purified beta-cells were exposed to the same cytokines. After 9 days, the apoptosis index was similarly increased in WT (39 +/- 3%) and iNOS4-/- (33 +/- 4%) beta-cells. On the other hand, cytokines increased necrosis in WT (20 +/- 4%) but not in iNOS-/- (7 +/- 3%) beta-cells. From these data, we concluded that 1) NO is required for cytokine-induced hsp 70 mRNA expression but not for Fas and MnSOD expression, 2) cytokines induce both apoptosis and necrosis in mouse beta-cells, and 3) cytokine-induced apoptosis is mostly NO-independent, whereas necrosis requires NO formation.
Diabetes 2000 Jul
PMID:Cytokines induce apoptosis in beta-cells isolated from mice lacking the inducible isoform of nitric oxide synthase (iNOS-/-). 1090 67


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