The effect of irradiation on the development of streptozotocin diabetes in C57BL/KsJY mice heterozygous and homozygous for gene db (diabetes)

In experiments with C57BL/KsJY mice carrying a mutant db gene at the heterozygous and homozygous states it has been found that db+/+db mice are much more sensitive to gamma radiation with respect to the survival rate. In homozygotes, in contrast to heterozygotes, irradiation with a dose of 6 Gy does not reduce the severity of the diabetogenic effect of low doses of streptozotocin.     

Reactive oxygen species-selective regulation of aortic inflammatory gene expression in Type 2 diabetes

Vascular diseases are a major complication of diabetes mellitus (DM), although their etiology is poorly understood. NADPH oxidase-derived reactive oxygen species (ROS) production and inflammation are potential mediators of DM-associated vascular diseases. Using db/db mice as a Type 2 diabetes model, we examined the relationship between NADPH oxidase-derived ROS and vascular inflammation. When compared with control m+/+ mice, aortas from 4- and 12-wk-old db/db mice had higher NADPH oxidase activity and increased superoxide levels, leading to NADPH oxidase-dependent impaired vasodilation at 12 wk. Diabetes progression from 4 to 12 wk led to increased Nox1, Nox4, and p22(phox) subunit mRNAs and induced the expression of a group of matrix remodeling-related cytokines: connective tissue growth factor (CTGF), bone morphogenetic protein 4 (BMP-4), and osteopontin (OPN). After 8 wk of treatment with the superoxide scavenger Tempol, 12-wk-old db/db mice had lower superoxide production, reduced plasma glucose and lipids, and lower BMP-4 and OPN protein expression when compared with nontreated mice. No changes were observed with Tempol in CTGF or m+/+ mice. The ability of Tempol to reverse ROS production as well as OPN and BMP-4, but not CTGF, induction suggests that DM-induced vascular inflammation involves both ROS-sensitive and -insensitive pathways.     

Adipose tissue in offspring of Lepr(db/+) mice: early-life environment vs. genotype

Gravidas with obesity and diabetes ("diabesity") may transmit this syndrome to their children through genetic and nongenetic mechanisms. Here, we used the Lepr(db/+) diabese mouse to examine the magnitude of these transmission modes, focusing on adipose tissue (AT). We compared the following six groups: wild-type (+/+) offspring from +/+ or db/+ dams (different early life environment) and db/+ offspring from db/+ dams, fed a standard or high-fat diet. Weight gain (0-8 wk) was higher in +/+ offspring from db/+ vs. +/+ mothers, and even higher in db/+ vs. +/+ offspring from db/+ mothers. In addition, we observed a stepwise increase in AT and adipocyte size in +/+ from +/+ mice, +/+ from db/+ mice, and db/+ mice at 8 wk. Differences in weight and adiposity between +/+ offspring from db/+ vs. +/+ dams were more pronounced in males than in females. Leptin and apelin mRNA levels in white and brown AT were higher in +/+ offspring from db/+ vs. +/+ dams; however, leptin, apelin, and tumor necrosis factor-alpha expression were boosted more robustly in db/+ offspring. The high-fat diet amplified AT differences between db/+ vs. +/+ offspring from db/+ dams, but not between +/+ offspring from db/+ vs. +/+ dams. Moreover, db/+ but not +/+ offspring from db/+ mothers were insulin-resistant and hyperinsulinemic after a glucose challenge. In conclusion, the genetic transmission of the diabesity phenotype clearly prevailed, but the early-life diabesity environment had discernible effects on postnatal weight gain as well as on adipocyte size and adipokine expression at a postpubertal age.     

Altered macrophage function is associated with severe Burkholderia pseudomallei infection in a murine model of type 2 diabetes

This study used a murine model of type 2 diabetes (BKS.Cg-Dock7(m) +/+Lepr(db)/J mice) to investigate the inflammatory and cellular mechanisms predisposing to Burkholderia pseudomallei infection and co-morbid diabetes. Homozygous db/db (diabetic) mice developed extreme obesity, dyslipidaemia and glucose intolerance leading to hyperglycaemia and overt type 2 diabetes. Compared to their heterozygous db/+ (non-diabetic) littermates, diabetic mice rapidly succumbed to subcutaneous B. pseudomallei infection, paralleled by severe hypoglycaemia and increased expression of the proinflammatory cytokines, tumour necrosis factor (TNF)-α and interleukin (IL)-1β, in the spleen, despite comparable bacterial loads in the spleen of non-diabetic mice. Neutrophil oxidative burst and dendritic cell uptake and killing of B. pseudomallei were similar between diabetic and non-diabetic mice. Compared to peritoneal macrophages from non-diabetic mice, macrophages from diabetic mice were unable to contain and kill B. pseudomallei. Functional differences between macrophages of diabetic and non-diabetic mice toward B. pseudomallei may contribute to rapid dissemination and more severe disease progression in hosts with co-morbid type 2 diabetes.     

Glucose metabolism in perfused mouse hearts overexpressing human GLUT-4 glucose transporter

Glucose and fatty acid metabolism was assessed in isolated working hearts from control C57BL/KsJ-m+/+db mice and transgenic mice overexpressing the human GLUT-4 glucose transporter (db/+-hGLUT-4). Heart rate, coronary flow, cardiac output, and cardiac power did not differ between control hearts and hearts overexpressing GLUT-4. Hearts overexpressing GLUT-4 had significantly higher rates of glucose uptake and glycolysis and higher levels of glycogen after perfusion than control hearts, but rates of glucose and palmitate oxidation were not different. Insulin (1 mU/ml) significantly increased glycogen levels in both groups. Insulin increased glycolysis in control hearts but not in GLUT-4 hearts, whereas glucose oxidation was increased by insulin in both groups. Therefore, GLUT-4 overexpression increases glycolysis, but not glucose oxidation, in the heart. Although control hearts responded to insulin with increased rates of glycolysis, the enhanced entry of glucose in the GLUT-4 hearts was already sufficient to maximally activate glycolysis under basal conditions such that insulin could not further stimulate the glycolytic rate.     

Connective Tissue Growth Factor (CTGF) Expression Modulates Response to High Glucose

Connective tissue growth factor (CTGF) is an important mediator of fibrosis; emerging evidence link changes in plasma and urinary CTGF levels to diabetic kidney disease. To further ascertain the role of CTGF in responses to high glucose, we assessed the consequence of 4 months of streptozotocin-induced diabetes in wild type (+/+) and CTGF heterozygous (+/−) mice. Subsequently, we studied the influence of glucose on gene expression and protein in mice embryonic fibroblasts (MEF) cells derived from wildtype and heterozygous mice. At study initiation, plasma glucose, creatinine, triglyceride and cholesterol levels were similar between non-diabetic CTGF+/+ and CTGF+/− mice. In the diabetic state, plasma glucose levels were increased in CTGF+/+ and CTGF+/− mice (28.2 3.3 mmol/L vs 27.0 3.1 mmol/L), plasma triglyceride levels were lower in CTGF+/− mice than in CTGF+/+ (0.7 0.2 mmol/L vs 0.5 0.1 mmol/L, p<0.05), but cholesterol was essentially unchanged in both groups. Plasma creatinine was higher in diabetic CTGF+/+ group (11.7±1.2 vs 7.9±0.6 µmol/L p<0.01), while urinary albumin excretion and mesangial expansion were reduced in diabetic CTGF+/− animals. Cortices from diabetic mice (both CTGF +/+ and CTGF +/−) manifested higher expression of CTGF and thrombospondin 1 (TSP1). Expression of nephrin was reduced in CTGF +/+ animals; this reduction was attenuated in CTGF+/− group. In cultured MEF from CTGF+/+ mice, glucose (25 mM) increased expression of pro-collagens 1, IV and XVIII as well as fibronectin and thrombospondin 1 (TSP1). In contrast, activation of these genes by high glucose was attenuated in CTGF+/− MEF. We conclude that induction of Ctgf mediates expression of extracellular matrix proteins in diabetic kidney. Thus, genetic variability in CTGF expression directly modulates the severity of diabetic nephropathy.     

Effect of mutant genes db(diabetes) and m(misty) on the severity of high-dose streptozotocin diabetes in C57bl/KsJY mice]

It is stated that high-dose streptozotocin diabetes is more serious in gene db-homozygous mice of mutant line C57BL/KsJY than in heterozygotes db +/+ m and mice M+/+m. Manifestation of spontaneous insulin-independent diabetes mellitus in homozygotes db decreases the level of hyperglycemic streptozotocin-induced reactions.     

Possible involvement of corticosterone in bone loss of genetically diabetic db/db mice.

The etiology of bone loss in non-insulin dependent diabetes mellitus is still unknown. We compared serum biochemical parameters and bone parameters of genetically diabetic db/db mice with those of their control non-diabetic +/+ mice. We found that serum corticosterone levels of the db/db mice were significantly elevated after 5 weeks while bone mineral density of femur metaphysis significantly decreased in the db/db mice after 12 weeks of age compared with age matched +/+ mice. To explore the causal relationship between the serum corticosterone levels and the bone loss, metyrapone (100 mg/kg, p.o., twice a day), a glucocorticoid synthesis inhibitor, was administered to these mice for 4 weeks after the age of 8 weeks. The compound significantly decreased serum corticosterone levels in both strains. Metyrapone prevented bone loss by increasing the bone mineral content of the metaphysis in the db/db mice. In addition, the treatment slightly improved the ratio of ash weight to dry weight in the db/db mice. These results suggest that increased serum corticosterone levels are concerned with the etiology of bone loss in non-insulin dependent diabetic db/db mice.     

Deletion of SERP1/RAMP4, a component of the endoplasmic reticulum (ER) translocation sites, leads to ER stress

Stress-associated endoplasmic reticulum (ER) protein 1 (SERP1), also known as ribosome-associated membrane protein 4 (RAMP4), is a Sec61-associated polypeptide that is induced by ER stress. SERP1-/- mice, made by targeted gene disruption, demonstrated growth retardation, increased mortality, and impaired glucose tolerance. Consistent with high levels of SERP1 expression in pancreas, pancreatic islets from SERP1-/- mice failed to rapidly synthesize proinsulin in response to a glucose load. In addition, reduced size and enhanced ER stress were observed in the anterior pituitary of SERP1-/- mice, and growth hormone production was slowed in SERP1-/- pituitary after insulin stimulation. Experiments using pancreatic microsomes revealed aberrant association of ribosomes and the Sec61 complex and enhanced ER stress in SERP1-/- pancreas. In basal conditions, the Sec61 complex in SERP1-/- microsomes was more cofractionated with ribosomes, compared with SERP1+/+ counterparts, in high-salt conditions. In contrast, after glucose stimulation, the complex showed less cofractionation at an early phase (45 min) but more at a later phase (120 min). Although intracellular insulin/proinsulin levels were not significantly changed in both genotypes, these results suggest that subtle changes in translocation efficiency play an important role in the regulation of ER stress and rapid polypeptide synthesis.     

FoxO1 as a double-edged sword in the pancreas: analysis of pancreas- and β-cell-specific FoxO1 knockout mice

Diabetes is characterized by an absolute or relative deficiency of pancreatic β-cells. New strategies to accelerate β-cell neogenesis or maintain existing β-cells are desired for future therapies against diabetes. We previously reported that forkhead box O1 (FoxO1) inhibits β-cell growth through a Pdx1-mediated mechanism. However, we also reported that FoxO1 protects against β-cell failure via the induction of NeuroD and MafA. Here, we investigate the physiological roles of FoxO1 in the pancreas by generating the mice with deletion of FoxO1 in the domains of the Pdx1 promoter (P-FoxO1-KO) or the insulin 2 promoter (β-FoxO1-KO) and analyzing the metabolic parameters and pancreatic morphology under two different conditions of increased metabolic demand: high-fat high-sucrose diet (HFHSD) and db/db background. P-FoxO1-KO, but not β-FoxO1-KO, showed improved glucose tolerance with HFHSD. Immunohistochemical analysis revealed that P-FoxO1-KO had increased β-cell mass due to increased islet number rather than islet size, indicating accelerated β-cell neogenesis. Furthermore, insulin-positive pancreatic duct cells were increased in P-FoxO1-KO but not β-FoxO1-KO. In contrast, db/db mice crossed with P-FoxO1-KO or β-FoxO1-KO showed more severe glucose intolerance than control db/db mice due to decreased glucose-responsive insulin secretion. Electron microscope analysis revealed fewer insulin granules in FoxO1 knockout db/db mice. We conclude that FoxO1 functions as a double-edged sword in the pancreas; FoxO1 essentially inhibits β-cell neogenesis from pancreatic duct cells but is required for the maintenance of insulin secretion under metabolic stress.     

Tetrathiomolybdate is partially protective against hyperglycemia in rodent models of diabetes

The objective was to evaluate whether copper lowering therapy with tetrathiomolybdate (TM) affected blood sugar levels in three rodent models of diabetes, streptozotocin (STZ) treated rats and mice, and the db/db mouse model. STZ was administered to rats and mice, and blood sugar levels were followed over a protracted time in these and non-STZ control animals. TM was administered by oral gavage (rats) or in the drinking water (mice) to a portion of the rats and mice to observe effects on blood sugar. Mice with genetically determined diabetes (db/db) were studied by giving half the mice TM in the drinking water and following blood sugar. The results show that TM caused a significant reduction in blood glucose in both STZ treated rats and mice, but no effect on blood glucose in db/db mice. However, TM caused a significant reduction in proteinuria in db/db animals. The results are discussed around the likelihood that TM is inhibiting ongoing inflammatory damage in the pancreas from STZ. A metabolic effect of TM on blood glucose is possible but seems less likely. TM is also likely inhibiting inflammatory and/or fibrogenic effects in the kidneys of db/db mice.     

Evidence for an interaction between leptin, T cell costimulatory antigens CD28, CTLA-4 and CD26 (dipeptidyl peptidase IV) in BCG-induced immune responses of leptin- and leptin receptor-deficient mice

We assessed changes of the enzyme dipeptidyl peptidase IV (DPP IV, CD26) in the context of leptin or leptin receptor deficiency. C57BL/6 mice, Leptin-deficient mice (ob/ob mice, B6.V-Lep) and Leptin-receptor-deficient mice (db/db mice, B6.Cg-m+/+Lepr) were infected with B. Calmette-Guerin (BCG) and sacrificed three days later. DPP IV activity in serum was higher in ob/ob mice and in db/db mice than in wild-type mice. The expression of DPP IV/CD26 on splenocytes was higher in ob/ob mice than in wild-type animals, and lower in db/db mice, and decreased upon stimulation with BCG in ob/ob mice only. Several T cell antigens including CTLA-4 were expressed aberrantly in ob/ob and in db/db mice. Our observations provide evidence for a relationship between DPP IV and leptin.     

Chronic Resveratrol Treatment Protects Pancreatic Islets against Oxidative Stress in db/db Mice

Resveratrol (RSV) has anti-inflammatory and anti-oxidant actions which may contribute to its cardiovascular protective effects. We examined whether RSV has any beneficial effects on pancreatic islets in db/db mice, an animal model of type 2 diabetes. The db/db and db/dm mice (non-diabetic control) were treated with (db-RSV) or without RSV (db-control) (20 mg/kg daily) for 12 weeks. After performing an intraperitoneal glucose tolerance test and insulin tolerance test, mice were sacrificed, the pancreas was weighed, pancreatic β-cell mass was quantified by point count method, and the amount of islet fibrosis was determined. 8-Hydroxydeoxyguanosine (8-OHdG), an oxidative stress marker, was determined in 24 h urine and pancreatic islets. RSV treatment significantly improved glucose tolerance at 2 hrs in db/db mice (P = 0.036), but not in db/dm mice (P = 0.623). This was associated with a significant increase in both pancreas weight (P = 0.011) and β-cell mass (P = 0.016). Islet fibrosis was much less in RSV-treated mice (P = 0.048). RSV treatment also decreased urinary 8-OHdG levels (P = 0.03) and the percentage of islet nuclei that were positive for 8-OHdG immunostaining (P = 0.019). We conclude that RSV treatment improves glucose tolerance, attenuates β-cell loss, and reduces oxidative stress in type 2 diabetes. These findings suggest that RSV may have a therapeutic implication in the prevention and management of diabetes.     

Immunoreactive C-peptide in spontaneous syndromes of obesity and diabetes in mice

Immunoreactive C-peptide was evaluated in the plasma and pancreas of Aston ob/ob and C57BL/KsJ db/db mice in relation to disturbances in pancreatic B-cell function. At 18-24 weeks of age, ob/ob and db/db mice displayed hyperglycaemia (1.6 and 3.8 fold increases respectively) and hyperinsulinaemia (10.8 and 5.1 fold increases respectively) despite a similar pancreatic insulin content to their respective non-diabetic lean control mice. Immunoreactive C-peptide concentrations in the plasma and pancreas of the mutants corresponded with the degree of hyperinsulinaemia and pancreatic insulin content, and the insulin: C-peptide molar ratios in both mutants were similar to lean controls. In ob/ob mice parenteral glucose administration decreased plasma insulin and C-peptide concentrations, despite markedly raised glucose concentrations. However, administration of a low dose of insulin (5 U/kg) to lean mice and much higher doses of insulin (50 and 120 U/kg) to ob/ob mice markedly decreased plasma glucose and C-peptide concentrations. When the rate and extent of insulin-induced glucose suppression observed in ob/ob mice was mimicked in lean mice, an almost complete (95%) inhibition of C-peptide was achieved compared with a 57% decrease in the ob/ob mutant. Injection of ob/ob mice with glucose to counter the insulin-induced hypoglycaemia failed to affect the fall of C-peptide concentrations. The data suggest that the metabolic processing of insulin and C-peptide are undisturbed in obese-diabetic mice, and that the impaired suppression of circulating C-peptide by insulin-hypoglycaemia in ob/ob mice predominantly reflects impaired feedback inhibition by insulin.     

Trypanosoma brucei: infection in murine diabetes

The course of infection due to Trypanosoma brucei infection was observed in genetically diabetic and streptozotocin-induced diabetic mice. A strain of T. brucei, TREU 667, was used which produces a chronic infection in C57BL/6(B6) mice lasting greater than 60 days. Genetic diabetic mice (+db/+db) are obese, and have elevated blood glucose levels, normal levels of insulin, and impaired cell-mediated immunity. Their littermates (m+/m+, m+/+db) are of normal weight, and are normoglycemic and immunocompetent. The infected +db/+db mice lived significantly longer than the nondiabetic littermates. In contrast to this finding, streptozotocin-induced diabetic B6 mice developed higher parasitemia and had shorter survival times than control B6 mice. Continuous treatment with insulin of these streptozotocin-induced diabetic mice led to normalization of blood glucose and a significant reduction of parasitemia. While hyperglycemia may be associated with higher parasitemia and death in streptozotozin-induced diabetes, genetic factors may play an additional role in the genetic models.     

Targeted disruption of the Ceacam1 (MHVR) gene leads to reduced susceptibility of mice to mouse hepatitis virus infection

The CEACAM1 glycoproteins (formerly called biliary glycoproteins; BGP, C-CAM, CD66a, or MHVR) are members of the carcinoembryonic antigen family of cell adhesion molecules. In the mouse, splice variants of CEACAM1 have either two or four immunoglobulin (Ig) domains linked through a transmembrane domain to either a short or a long cytoplasmic tail. CEACAM1 has cell adhesion activity and acts as a signaling molecule, and long-tail isoforms inhibit the growth of colon and prostate tumor cells in rodents. CEACAM1 isoforms serve as receptors for several viral and bacterial pathogens, including the murine coronavirus mouse hepatitis virus (MHV) and Haemophilus influenzae, Neisseria gonorrhoeae, and Neisseria meningitidis in humans. To elucidate the mechanisms responsible for the many biological activities of CEACAM1, we modified the expression of the mouse Ceacam1 gene in vivo. Manipulation of the Ceacam1 gene in mouse embryonic stem cells that contained the Ceacam1a allele yielded a partial knockout. We obtained one line of mice in which the insert in the Ceacam1a gene had sustained a recombination event. This resulted in the markedly reduced expression of the two CEACAM1a isoforms with four Ig domains, whereas the expression of the two isoforms with two Ig domains was doubled relative to that in wild-type BALB/c (+/+) mice. Homozygous (p/p) Ceacam1a-targeted mice (Ceacam1aDelta4D) had no gross tissue abnormalities and were viable and fertile; however, they were more resistant to MHV A59 infection and death than normal (+/+) mice. Following intranasal inoculation with MHV A59, p/p mice developed markedly fewer and smaller lesions in the liver than +/+ or heterozygous (+/p) mice. The titers of virus produced in the livers were 50- to 100-fold lower in p/p mice than in +/p or +/+ mice. p/p mice survived a dose 100-fold higher than the lethal dose of virus for +/+ mice. +/p mice were intermediate between +/+ and p/p mice in susceptibility to liver damage, virus growth in liver, and susceptibility to killing by MHV. Ceacam1a-targeted mice provide a new model to study the effects of modulation of receptor expression on susceptibility to MHV infection in vivo.     

Glucose catabolic gene mRNA levels in skeletal muscle exhibit non-coordinate expression in hyperglycemic mice.

To assess the correlation between hyperglycemia and glucose catabolic gene levels in diabetic and healthy mice, we determined mRNA levels of pivotal proteins such as glucose transporters, hexokinase II, glycogen synthase, glutamine:fructose-6-phosphate amidotransferase and uncoupling proteins. Both KK and KKAy mice showed marked decreases of Glut1 and Glut4 mRNA levels in soleus compared to C57BL; db/db and ob/ob mice exhibited significantly decreased Glut4 mRNA levels, but not Glut1, in soleus. KK and KKAy mice showed a decrease of soleus HKII gene level, which may indicate decreased intracellular catabolism of glucose. Likewise, GS mRNA level was decreased in soleus muscle tissue in KK and KKAy mice. GFAT mRNA levels was no different between hyperglycemic and normoglycemic mice. In contrast, UCP2 and UCP3 mRNA levels were higher in KK and KKAy mice. Conversely, db/db and ob/ob mice showed a significant decrease in UCP3 mRNA. Individual correlation analysis indicated that the decrease in Glut4 gene levels was only observed in hyperglycemic mice. The more important observation is that the glucose catabolic genes do not exhibit any clear coordinate expression. Abnormal expression of glucose catabolic genes may contribute to hyperglycemia and muscle insulin resistance in these four strains.     

两种自发性2型糖尿病小鼠生物学特性比较

目的分别以C57BL/6JSlac和C57BL/KsJ-db/＋表型正常小鼠为对照组,比较自发性2型糖尿病KK-Ay/Ta和C57BL/KsJ-db/db小鼠的体生长曲线、糖代谢曲线、血清胰岛素水平、主要脏器重量、脏器系数等生物学特性的差异,并探讨其肾脏、肝脏和胰腺等组织病理学变化。方法在各自实验周期内,每2周测定实验组和对照组小鼠的体重、血糖以及血清胰岛素水平,实验结束后处死,脏器、脂肪称重,部分组织制作病理切片。结果 （1）KK小鼠体重远高于db/db小鼠,且同品系间雄性小鼠重于雌性小鼠（P〈0.05）;（2）同品系间雄性小鼠的血糖值明显大于雌性小鼠（P〈0.05）,db/db小鼠出现血糖异常症状比KK小鼠早,且血糖值大于KK小鼠（P〈0.05）,而KK小鼠血糖异常持续时间则较db/db小鼠长;（3）KK小鼠的血清胰岛素水平明显高于db/db小鼠（P〈0.05）,同品系雌雄小鼠间没有明显差异（P〉0.05）;（4）雄性KK小鼠脂肪系数及部分脏器萎缩程度大于雌性,而db/db小鼠雌雄间则无明显差异（P〉0.05）,同时db/db小鼠脾脏和胰腺的萎缩程度及脂肪系数大于KK小鼠（P〈0.05）,而KK小鼠肝脏的萎缩程度则大于db/db小鼠;（5）糖尿病模型小鼠肾脏、肝脏以及胰腺组织均出现明显病变。结论 KK-Ay/Ta和C57BL/KsJ-db/db小鼠均是肥胖的,伴有高血糖、高度胰岛素抵抗,肝脏、肾脏病变和胰岛功能不足的适用性2型糖尿病动物模型,且db/db小鼠血糖出现异常比KK小鼠早、脂肪系数大,而KK小鼠血糖异常持续时间较db/db小鼠长,同时血清胰岛素水平远大于db/db小鼠。     

ATM-dependent suppression of stress signaling reduces vascular disease in metabolic syndrome

Metabolic syndrome is associated with insulin resistance and atherosclerosis. Here, we show that deficiency of one or two alleles of ATM, the protein mutated in the cancer-prone disease ataxia telangiectasia, worsens features of the metabolic syndrome, increases insulin resistance, and accelerates atherosclerosis in apoE-/- mice. Transplantation with ATM-/- as compared to ATM+/+ bone marrow increased vascular disease. Jun N-terminal kinase (JNK) activity was increased in ATM-deficient cells. Treatment of ATM+/+apoE-/- mice with low-dose chloroquine, an ATM activator, decreased atherosclerosis. In an ATM-dependent manner, chloroquine decreased macrophage JNK activity, decreased macrophage lipoprotein lipase activity (a proatherogenic consequence of JNK activation), decreased blood pressure, and improved glucose tolerance. Chloroquine also improved metabolic abnormalities in ob/ob and db/db mice. These results suggest that ATM-dependent stress pathways mediate susceptibility to the metabolic syndrome and that chloroquine or related agents promoting ATM activity could modulate insulin resistance and decrease vascular disease.     

Accumulation of proteinase K-resistant prion protein (PrP) is restricted by the expression level of normal PrP in mice inoculated with a mouse-adapted strain of the Creutzfeldt-Jakob disease agent.

Creutzfeldt-Jakob disease (CJD) is a transmissible neurodegenerative disease of humans caused by an unidentified infectious agent, the prion. To determine whether there was an involvement of the host-encoded prion protein (PrPc) in CJD development and prion propagation, mice heterozygous (PrP+/-) or homozygous (PrP-/-) for a disrupted PrP gene were established and inoculated with the mouse-adapted CJD agent. In keeping with findings of previous studies using other lines of PrP-less mice inoculated with scrapie agents, no PrP-/- mice showed any sign of the disease for 460 days after inoculation, while all of the PrP+/- and control PrP+/+ mice developed CJD-like symptoms and died. The incubation period for PrP+/- mice, 259 +/- 27 days, was much longer than that for PrP+/+ mice, 138 +/- 12 days. Propagation of the prion was barely detectable in the brains of PrP-/- mice and was estimated to be at a level at least 4 orders of magnitude lower than that in PrP+/+ mice. These findings indicate that PrPc is necessary for both the development of the disease and propagation of the prion in the inoculated mice. The proteinase-resistant PrP (PrPres) was undetectable in the brain tissues of the inoculated PrP-/- mice, while it accumulated in the affected brains of PrP+/+ and PrP+/- mice. Interestingly, the maximum level of PrPres in the brains of PrP+/- mice was about half of the level in the similarly affected brains of PrP+/+ mice, indicating that PrPres accumulation is restricted by the level of PrPc.