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

We have used the 3T3-L1 and 3T3-F442A preadipocyte cell lines to examine the expression and regulation of neuronal apoptosis inhibitory protein (NAIP) during adipocyte differentiation. When 3T3-L1 preadipocytes differentiated into adipocytes, they developed resistance to apoptosis induced by growth factor deprivation, as assessed by terminal deoxynucleotide transferase (TdT)-mediated dUTP nick end labeling. Protein expression of NAIP was markedly elevated in 3T3-L1 and 3T3-F442A adipocytes compared with that in their fibroblast-like precursors. NAIP was also present in rat white adipocytes. In 3T3-L1 cells, the increase in NAIP occurred by day 4 of the 8-day differentiation protocol, which includes exposure of confluent preadipocytes to insulin, dexamethasone, and isobutylmethylxanthine. Incubation of confluent 3T3-L1 preadipocytes with any of these components alone had no effect on NAIP expression. When 3T3-C2 cells, a control cell line that does not differentiate, were subjected to the differentiation protocol, the low NAIP levels remained unaltered. Addition of rapamycin, a p70 S6 kinase inhibitor that blocks adipocyte differentiation, to the 3T3-L1 differentiation medium prevented the rise in NAIP expression. These data demonstrate for the first time that NAIP is expressed in adipocyte cell lines and primary adipocytes. The differentiation-dependent augmentation of NAIP protein levels in 3T3-L1 adipocytes is closely correlated with the development of resistance to apoptosis induced by growth factor deprivation, suggesting a potential role for NAIP in these cells.
Diabetes 1998 Dec
PMID:Expression and regulation of neuronal apoptosis inhibitory protein during adipocyte differentiation. 983 29

We have investigated the cellular pathology of the syndrome called thiamine-responsive megaloblastic anemia (TRMA) with diabetes and deafness. Cultured diploid fibroblasts were grown in thiamine-free medium and dialyzed serum. Normal fibroblasts survived indefinitely without supplemental thiamine, whereas patient cells died in 5-14 days (mean 9.5 days), and heterozygous cells survived for more than 30 days. TRMA fibroblasts were rescued from death with 10-30 nM thiamine (in the range of normal plasma thiamine concentrations). Positive terminal deoxynucleotide transferase-mediated dUTP nick end-labeling (TUNEL) staining suggested that cell death was due to apoptosis. We assessed cellular uptake of [3H]thiamine at submicromolar concentrations. Normal fibroblasts exhibited saturable, high-affinity thiamine uptake (Km 400-550 nM; Vmax 11 pmol/min/10(6) cells) in addition to a low-affinity unsaturable component. Mutant cells lacked detectable high-affinity uptake. At 30 nM thiamine, the rate of uptake of thiamine by TRMA fibroblasts was 10-fold less than that of wild-type, and cells from obligate heterozygotes had an intermediate phenotype. Transfection of TRMA fibroblasts with the yeast thiamine transporter gene THI10 prevented cell death when cells were grown in the absence of supplemental thiamine. We therefore propose that the primary abnormality in TRMA is absence of a high-affinity thiamine transporter and that low intracellular thiamine concentrations in the mutant cells cause biochemical abnormalities that lead to apoptotic cell death.
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PMID:Defective high-affinity thiamine transporter leads to cell death in thiamine-responsive megaloblastic anemia syndrome fibroblasts. 1007 90

To determine the roles of the ATP-sensitive K+ (K(ATP)) channels in endocrine pancreas more directly, two types of genetically engineered Kir6.2 mice were developed: mice expressing a dominant-negative form of Kir6.2 specifically in beta-cells (Kir6.2G132S Tg mice) and mice lacking Kir6.2 (Kir6.2-/- or Kir6.2 null mice). The Kir6.2G132S Tg mice show severe impairment of K(ATP) channel function only in the beta-cells, whereas Kir6.2 null mice are completely defective in K(ATP) channel function in all of the cells in which Kir6.2 is a constituent of the K(ATP) channels, because of the disruption of Kir6.2. Both types of mice show abnormal architecture of the pancreatic islets. The number of beta-cells in Kir6.2G132S Tg mice decreases markedly with age, whereas that in Kir6.2-/- mice decreases slightly. alpha-Cells, which are normally present only in the periphery of pancreatic islets, also appear in the center of the islets in both Kir6.2G132S Tg and Kir6.2-/- mice. Interestingly, the number of peptide YY (PYY) and glucagon-positive cells is markedly increased in Kir6.2 null mice, whereas the number of PP cells and delta-cells is not altered. Apoptotic cells are detected by the TdT-mediated dUTP nick-end labeling (TUNEL) method at a high frequency in both Kir6.2G372S Tg and Kir6.2-/- mice compared with the respective controls. Thus, studies of Kir6.2G372S Tg and Kir6.2-/- mice indicate that K(ATP) channels play an important role in cell survival and differentiation in the endocrine pancreas.
Diabetes 2001 Feb
PMID:Roles of ATP-sensitive K+ channels in cell survival and differentiation in the endocrine pancreas. 1127 1

Cytokines produced by immune system cells that infiltrate pancreatic islets are candidate mediators of islet beta-cell destruction in autoimmune (type 1) diabetes mellitus. Because the calcium binding protein, calbindin-D(28k), can prevent apoptotic cell death in different cell types, we investigated the possibility that calbindin-D(28k) may prevent cytokine-mediated islet beta-cell destruction. Using the expression vector BSRalpha, rat calbindin-D(28k) was stably expressed in the pancreatic islet beta-cell line, betaTC-3. Calbindin-D(28k) expression resulted in increased cell survival in the presence of the cytotoxic combination of the cytokines IL-1beta (30 U/ml), TNFalpha (10(3) U/ml), and interferon gamma (10(3) U/ml). The greatest protection was observed in the betaTC-3 cell clone expressing the highest concentration of calbindin-D(28k). Apoptotic cell death was detected by annexin V staining and by the TdT-mediated dUTP-X nick end labeling assay in vector-transfected betaTC-3 cells incubated with cytokines (14-15% apoptotic cells). The number of apoptotic cells was significantly decreased in calbindin-D(28k)-overexpressing betaTC-3 cells incubated with cytokines (5-6% apoptotic cells). To address the mechanism of the antiapoptotic effects of calbindin, studies were done to examine whether calbindin inhibits free radical formation. The stimulatory effects of the cytokines on lipid hydroperoxide, nitric oxide, and peroxynitrite production were significantly decreased in the calbindin-D(28k)-expressing betaTC-3 cells. Our findings indicate that calbindin-D(28k), by inhibiting free radical formation, can protect against cytokine-mediated apoptosis and destruction of beta-cells. These findings suggest that calbindin-D(28k) may be an important regulator of cell death that can protect pancreatic islet beta-cells from autoimmune destruction in type 1 diabetes.
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PMID:Expression of calbindin-D(28k) in a pancreatic islet beta-cell line protects against cytokine-induced apoptosis and necrosis. 1145 14

Apoptosis has been observed in vascular cells, nerve, and myocardium of diabetic humans and experimental animals, although whether it contributes to or is a marker of complications in these tissues is unclear. Previous studies have shown that incubation of human umbilical vein endothelial cells (HUVECs) with 30 vs. 5 mmol/l glucose for 72 h causes a significant increase in apoptosis, possibly related to an increase in oxidative stress. We report here that this increase in apoptosis (assessed morphologically by TdT-mediated dUTP nick- end labeling staining) is preceded (24 h of incubation) by inhibition of fatty acid oxidation, by increases in diacylglycerol synthesis, the concentration of malonyl CoA, and caspase-3 activity, and by decreases in mitochondrial membrane potential and cellular ATP content. In addition, the phosphorylation of Akt in the presence of 150 microU/ml insulin was impaired. No increases in ceramide content or its de novo synthesis were observed. AMP-activated protein kinase (AMPK) activity was not diminished; however, incubation with the AMPK activator 5-aminoimidazole-4-carboxamide-riboside increased AMPK activity twofold and completely prevented all of these changes. Likewise, expression of a constitutively active AMPK in HUVEC prevented the increase in caspase-3 activity. The results indicate that alterations in fatty-acid metabolism, impaired Akt activation by insulin, and increased caspase-3 activity precede visible evidence of apoptosis in HUVEC incubated in a hyperglycemic medium. They also suggest that AMPK could play an important role in protecting the endothelial cell against the adverse effects of sustained hyperglycemia.
Diabetes 2002 Jan
PMID:Hyperglycemia-induced apoptosis in human umbilical vein endothelial cells: inhibition by the AMP-activated protein kinase activation. 1175 36

We investigated the effect of a chronic exposure to high levels of free fatty acid (FFA; 2 mmol/L oleate/palmitate 2:1) or glucose (16.7 mmol/L) on islet cell apoptosis. Apoptosis was detected using 4 different methods: (1) cell staining with annexin-V fluorescien isothiocyanate (FITC) conjugate and propidium iodide (PI); (2) quantification of cytoplasmatic DNA fragments by an enzyme-linked immunosorbent assay (ELISA); (3) assay of caspase 3 activity; and (4) TdT-mediated dUTP nick-end labeling (TUNEL). Islet cells were also costained with an anti-insulin antibody to identify apoptotic beta cells. We also evaluated by reverse-transcriptase polymerase chain reaction (RT-PCR) the expression of bax, bcl-2, and caspas 3, genes involved in apoptosis. In islets cultured for 7 days in the presence of high FFA or for 3 days in the presence of high glucose levels, we observed: (1) a 2- to 3-fold increase of apoptotic cells conjugated with annexin-V FITC and PI; (2) a 4- to 6-fold increase of cytoplasmatic DNA fragments; (3) a 3- to 4-fold increase of caspase 3 activity; and (4) a significant increase of insulin positive apoptotic cells as detected with the TUNEL method. RT-PCR analysis indicated in islets exposed to high FFA or glucose levels an increase of bax (proapoptotic gene), a reduction of bcl-2 (antiapoptotic gene), and a slight (although not significant) increase in caspase 3 expression. Western blot analysis also showed an increase of Bax protein levels in islets exposed to high FFA or glucose. The simultaneous presence of both metabolic abnormalities did not further increase the amount of apoptotic cells, although the time-course of the cellular damage induced by FFA was accelerated by the contemporary presence of high glucose. To elucidate the mechanism by which FFA and glucose may induce pancreatic beta-cell damage, we examined whether nicotinamide prevents apoptosis in pancreatic islets cultured for 7 days with high FFA or for 3 days with high glucose. Nicotinamide was able to prevent beta-cell damage by significantly reducing apoptosis in both experimental conditions. Also, the increase of Bax protein level was prevented by nicotinamide. These data indicate that chronic exposure to elevated FFA or glucose levels increases apoptosis in rat pancreatic islets and these cytotoxic effects could be mediated by oxidative stress. This may contribute to the beta-cell failure that occurs in most in type 2 diabetic patients few years after clinical diabetes onset.
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PMID:Chronic exposure to free fatty acids or high glucose induces apoptosis in rat pancreatic islets: possible role of oxidative stress. 1237 Aug 56

To explore mechanisms underlying central nervous system (CNS) complications in diabetes, we examined hippocampal neuronal apoptosis and loss, and the effect of C-peptide replacement in type 1 diabetic BB/W rats. Apoptosis was demonstrated after 8 months of diabetes, by DNA fragmentation, increased number of apoptotic cells, and an elevated ratio of Bax/Bcl-xL, accompanied by reduced neuronal density in the hippocampus. No apoptotic activity was detected and neuronal density was unchanged in 2-month diabetic hippocampus, whereas insulin-like growth factor (IGF) activities were impaired. In type 1 diabetic BB/W rats replaced with C-peptide, no TdT-mediated dUTP nick-end labeling (TUNEL)-positive cells were shown and DNA laddering was not evident in hippocampus at either 2 or 8 months. C-peptide administration prevented the preceding perturbation of IGF expression and reduced the elevated ratio of Bax/Bcl-xL. Our data suggest that type 1 diabetes causes a duration-dependent programmed cell death of the hippocampus, which is partially prevented by C-peptide.
Int J Exp Diabetes Res
PMID:C-peptide prevents hippocampal apoptosis in type 1 diabetes. 1254 77

Diabetes-induced early embryonic death is accompanied by an increased expression of tumour necrosis factor alpha (TNF-alpha) in the embryonic microenvironment. The aim of the present study was to evaluate whether diabetes-induced embryopathic stress may also alter the expression of TNF-alpha produced by the embryo itself. As a model, whole postimplantation embryos were cultured for 24 h in a medium with high concentrations of glucose, one of the main diabetes-associated teratogenic metabolites. An anomaly such as an open neural tube was used as an end-point characterizing the glucose-induced teratogenic effect and the number of somites was counted to evaluate growth retardation induced by glucose. The expression of TNF-alpha (by immunohistochemistry), apoptosis (by TdT-mediated dUTP nick-end labelling; TUNEL) and the activity of caspases 3 and 8 (by a fluorometric assay) were evaluated in normal and malformed embryos. Ninety-seven per cent of the embryos exposed to 1300 mg glucose dl(-1) exhibited an open neural tube. The percentage of malformed embryos was smaller in media containing 800 and 500 mg glucose dl(-1) (68 and 37%, respectively) but it still exceeded significantly the value registered in embryos developing in a normoglycaemic medium (12%). In addition, a significant decrease in the number of somites was observed in embryos developing in media containing 1300 and 800 mg glucose dl(-1). Malformed embryos exhibited a greater number of nuclei that were positive in the TUNEL assay as well as a higher amount of active caspase 8 compared with normal embryos (with closed neural folds). TNF-alpha expression was detected in the neuroepithelial layer of the neural tube of the malformed embryos, whereas the expression of this cytokine was weak, if detectable, in normal embryos. Together, these findings indicate that TNF-alpha produced by the embryo may be involved in regulating the response of embryos to diabetes-generated embryopathic stress.
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PMID:Increased TNF-alpha expression in cultured mouse embryos exposed to teratogenic concentrations of glucose. 1268 23

The wide diversity of the T and B Ag receptor repertoires becomes even more extensive postneonatally due to the activity of TdT, which adds nontemplated N nucleotides to Ig and TCR coding ends during V(D)J recombination. In addition, complementarity-determining region 3 sequences formed in the absence of TdT are more uniform due to the use of short sequence homologies between the V, D, and J genes. Thus, the action of TdT produces an adult repertoire that is both different from, and much larger than, the repertoire of the neonate. We have generated TdT-deficient nonobese diabetic (NOD) and MRL-Fas(lpr) mice, and observed a decrease in the incidence of autoimmune disease, including absence of diabetes and decreased pancreatic infiltration in NOD TdT(-/-) mice, and reduced glomerulonephritis and increased life span in MRL-Fas(lpr) TdT(-/-) mice. Using tetramer staining, TdT(-/-) and TdT(+/+) NOD mice showed similar frequencies of the diabetogenic BDC 2.5 CD4(+) T cells. We found no increase in CD4(+)CD25(+) regulatory T cells in NOD TdT(-/-) mice. Thus, TdT deficiency ameliorates the severity of disease in both lupus and diabetes, two very disparate autoimmune diseases that affect different organs, with damage conducted by different effector cell types. The neonatal repertoire appears to be deficient in autoreactive T and/or B cells with high enough affinities to induce end-stage disease. We suggest that the paucity of autoreactive specificities created in the N region-lacking repertoire, and the resultant protection afforded to the newborn, may be the reason that TdT expression is delayed in ontogeny.
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PMID:Terminal deoxynucleotidyltransferase deficiency decreases autoimmune disease in diabetes-prone nonobese diabetic mice and lupus-prone MRL-Fas(lpr) mice. 1503 81

This study was performed to determine whether early diabetes accelerates retinal neuronal cell death and inhibits neurite regeneration. Five of ten rats were rendered diabetic with streptozotocin injection. After 3 weeks of diabetes, retinas were isolated and retinal explants were cultured in serum-free media. On day 6, the number of neurites was counted in retinal explants obtained from control and diabetic rat retinas. To identify neuronal cells undergoing apoptosis, retinas were fixed, cryosections prepared, and TdT-dUTP terminal nick-end labeling (TUNEL) was performed. Furthermore, the expression of Bax was determined in the retinas by immunohistochemistry and Western blot analysis. The number of TUNEL-positive cells in the ganglion cell layer of diabetic retinas was significantly increased (144.8+/-33.6% of control, p<0.01) compared to those in non-diabetic control rats. The number of regenerating neurites in the retinal explants of diabetic rats was significantly reduced (63.2+/-25.1% of control, p<0.05). In retinal neuronal cells of the diabetic retinas, proapoptotic Bax expression determined by immunohistochemistry and Western blot analysis showed a significant increase compared to the non-diabetic control retinas (158.1+/-55.2% of control, p<0.01; 161.6+/-48.8% of control, p<0.01, respectively). The findings indicate that diabetes upregulates Bax expression, accelerates retinal neuronal cell death, and inhibits neurite regeneration in rat retinas. Thus, it is likely that Bax dependent pathways may be activated in injured neuronal cells of the diabetic retinas.
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PMID:Diabetes: a potential enhancer of retinal injury in rat retinas. 1615 73


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