OBJECTIVE: In type 2 diabetes, prevalence of nonalbuminuric renal impairment is increasing worldwide, though its clinical significance remains unclear. This large-cohort study aimed at evaluating the association of this phenotype with cardiovascular risk factors and other complications. METHODS: Type 2 diabetic patients from the Renal Insufficiency And Cardiovascular Events (RIACE) Italian Multicenter Study (n = 15,773), visiting consecutively 19 hospital-based Diabetes Clinics in years 2007-2008, were examined. Serum creatinine was assessed by the Jaffe method; albuminuria was measured by immunonephelometry or immunoturbidimetry. RESULTS: Of patients with renal impairment, as identified by an estimated glomerular filtration rate (eGFR) less than 60 ml/min per 1.73 m², 56.6% were normoalbuminuric, 30.8% were microalbuminuric, and 12.6% were macroalbuminuric. Percentages were similar when GFR was estimated using the more accurate Chronic Kidney Disease Epidemiology Collaboration equation instead of the simplified Modification of Diet in Renal Disease formula, and were independent of age, thus indicating that the increasing prevalence of this phenotype does not reflects misclassification of elderly patients. Nonalbuminuric renal impairment was not associated with HbA(1c) and correlated less strongly with retinopathy and hypertension than albuminuria, either alone or associated with reduced eGFR. It was associated with a higher prevalence of cardiovascular disease (CVD) than albuminuria alone, but lower than albuminuric renal impairment. Female sex correlated with nonalbuminuric renal impairment and male sex with the albuminuric forms. CONCLUSIONS: These data show that type 2 diabetic patients with nonalbuminuric renal impairment exhibit distinct clinical features, suggesting predominance of macroangiopathy as underlying renal pathology, and that this phenotype is associated with significant CVD burden.

In obese subjects with obstructive sleep apnea (OSA), chronic intermittent hypoxia (CIH) may be linked to systemic and adipose tissue inflammation.

Diabetes and cancer are worldwide chronic diseases with a major impact on the quality and expectancy of life. Metabolic abnormalities observed during the onset and progression of diabetes may have a critical role on the initiation and progression of carcinogenesis. To date, there are no conclusive data on the mechanisms underlying the relationship between diabetes and any type of human cancer. However, recent evidence suggests that both hyperglycemia and hyperinsulinemia in diabetes could elicit cell damage responses, such as glucotoxicity, lipotoxicity and oxidative stress, which participate in the cell transformation process raising the risk of cancer development. In addition, clinical trials have revealed that several anti-diabetes therapies may potentially affect the risk of cancer though largely undefined mechanisms. In this review, we highlight epidemiological and pathophysiological aspects of diabetes, which may influence cancer initiation and progression.

The The aim of our study is to investigate the molecular mechanisms of diabetic cardiomyopathy through the identification of remarkable genes for the myocardial function that are expressed differently between diabetic and normal subjects. Moreover, we intend to characterize both in human myocardial tissue and in the related cardiac progenitor cells the pattern of gene expression and the levels of expression and protein activation of molecular effectors involved in the regulation of the myocardial function and differentiation to clarify whether in specific human pathological conditions (type 2 diabetes mellitus, cardiac failure, coronary artery disease) specific alterations of the aforementioned factors could take place. Thirty-five patients scheduled for coronary artery bypass grafting (CABG) or for aortic or mitral valve replacement were recruited into the study. There were 13 men and 22 women with a mean age of 64.8 +/- 13.4 years. A list of anamnestic, anthropometric, clinical, and instrumental data required for an optimal phenotypical characterization of the patients is reported. The small cardiac biopsy specimens were placed in the nourishing buffer, in a sterile tube provided the day of the procedure, to maintain the stability of the sample for several hours at room temperature. The cells were isolated by a dedicated protocol and then cultured in vitro. The sample was processed for total RNA extraction and levels of gene expression and protein activation of molecular effectors involved in the regulation of function and differentiation of human myocardium was analyzed. In particular, cardiac genes that modulate the oxidative stress response or the stress induced by pro-inflammatory cytokines (p66Shc, SOCS-1, SOCS-3) were analyzed. From a small sample of myocardium cardiac stem cells and cardiomyoblasts were also isolated and characterized. These cells showed a considerable proliferative capacity due to the fact that they demonstrate stability up to the eleventh passage. Analysis of gene expression in a subgroup of subjects showed the trend of a decrease in levels of expression of cardiac-specific transcription genes and oxidative stress-related proteins in tissues of diabetic patients compared with controls subjects. This trend is not confirmed in isolated cells. As for the coronary artery disease, diabetic cardiomyopathy could be associated with a reduction of the cardiac stem and progenitor cells pool. The expansion of the cardiac resident cells pool could be associated with a preservation of cardiac performance, suggesting that a preserved stamina compartment can counteract the impact of diabetes on the myocardium.

Increased risk of osteoporosis and its clinical significance in patients with diabetes is controversial. This study aims to increase the data which are available regarding the prevalence of diabetes mellitus in patients affected by fragility fracture in Italy. We retrospectively studied Hospital Discharge Data (HDD) in the Apulian database for the period 2006–2010 to identify a fragility fracture diagnosis in males over 65 years of age and in females over 50. The database was then checked for drug prescriptions to identify those persons who had taken at least one osteoporosis drug. Within this latter group, thanks to hospital admission and prescription records, the subjects affected with diabetes mellitus were identified. Between 2006 and 2010 in Apulia 177,639 patients were hospitalized and diagnosed as having fragility fracture. The greatest number of those fragility fractures were found to be in the 70 to 79 age range (64,917 total; females 56,994, males 7,923). The prevalence of diabetes subjects in Apulia in this period was estimated at 6.5%. In the same region and period 21.1% of subjects affected by diabetes experienced a fragility fracture; in particular, this number was 27% for males and for 20.5% females. This is the first study providing data on the prevalence of fragility fractures and diabetes in the Apulian population. The data confirm that diabetes is a risk factor which influences bone density and risk of fractures and therefore the need of osteoporosis screening and treatment in diabetic patients.

Glucagon-like peptide-1 and its analogs may preserve pancreatic beta-cell mass by promoting resistance to cytokine-mediated apoptosis. The mechanisms of TNFalpha-induced apoptosis and of its inhibition by exendin-4 were investigated in insulin-secreting cells. INS-1 and MIN6 insulinoma cells were exposed to 20 ng/ml TNFalpha, with or without pretreatment with 10 nm exendin-4. Treatment with TNFalpha increased c-Jun N-terminal protein kinase (JNK) phosphorylation 2-fold, reduced inhibitor-kappaBalpha (IkappaBalpha) protein content by 50%, induced opposite changes in caspase-3 and Bcl-2 protein content, and increased cellular apoptosis. Moreover, exposure to TNFalpha resulted in increased serine phosphorylation of both insulin receptor substrate (IRS)-1 and IRS-2 and reduced basal and insulin-induced Akt phosphorylation. However, in the presence of a JNK inhibitor, TNFalpha-induced apoptosis was diminished and serine phosphorylation of IRS proteins was prevented. When cells were pretreated with exendin-4, TNFalpha-induced JNK and IRS-1/2 serine phosphorylation was markedly reduced, Akt phosphorylation was increased, caspase-3 and Bcl-2 protein levels were restored to normal, and TNFalpha-induced apoptosis was inhibited by 50%. This was associated with a 2-fold increase in IRS-2 expression levels. A similar ability of exendin-4 to prevent TNFalpha-induced JNK phosphorylation was found in isolated pancreatic human islets. The inhibitory effect of exendin-4 on TNFalpha-induced JNK phosphorylation was abrogated in the presence of the protein kinase A inhibitor H89. In conclusion, JNK activation mediates TNFalpha-induced apoptosis and impairment of the IRS/Akt signaling pathway in insulin-secreting cells. By inhibiting JNK phosphorylation in a PKA-dependent manner, exendin-4 counteracts TNFalpha-mediated apoptosis and reverses the inhibitory events in the IRS/Akt pathway, resulting in promotion of cell survival.

AIMS/HYPOTHESIS: The mechanisms of the protective effects of exendin-4 on NEFA-induced beta cell apoptosis were investigated. METHODS: The effects of exendin-4 and palmitate were evaluated in human and murine islets, rat insulin-secreting INS-1E cells and murine glucagon-secreting alpha-TC1-6 cells. mRNA and protein expression/phosphorylation were measured by real-time RT-PCR and immunoblotting or immunofluorescence, respectively. Small interfering (si)RNAs for Ib1 and Gpr40 were used. Cell apoptosis was quantified by two independent assays. Insulin release was assessed with an insulin ELISA. RESULTS: Exposure of human and murine primary islets and INS-1E cells, but not alpha-TC1-6 cells, to exendin-4 inhibited phosphorylation of the stress kinases, c-Jun N-terminal kinase (JNK) and p38 mitogen-activated protein kinase (MAPK), and prevented apoptosis in response to palmitate. Exendin-4 increased the protein content of islet-brain 1 (IB1), an endogenous JNK blocker; however, siRNA-mediated reduction of IB1 did not impair the ability of exendin-4 to inhibit JNK and prevent apoptosis. Exendin-4 reduced G-protein-coupled receptor 40 (GPR40) expression and inhibited palmitate-induced phosphorylation of mitogen-activated kinase kinase (MKK)4 and MKK7. The effects of exendin-4 were abrogated in the presence of the protein kinase A (PKA) inhibitors, H89 and KT5720. Knockdown of GPR40, as well as use of a specific GPR40 antagonist, resulted in diminished palmitate-induced JNK and p38 MAPK phosphorylation and apoptosis. Furthermore, inhibition of JNK and p38 MAPK activity prevented palmitate-induced apoptosis. CONCLUSIONS/INTERPRETATION: Exendin-4 counteracts the proapoptotic effects of palmitate in beta cells by reducing GPR40 expression and inhibiting MKK7- and MKK4-dependent phosphorylation of the stress kinases, JNK and p38 MAPK, in a PKA-dependent manner.

Increased apoptosis of cardiac progenitor cells (CPCs) has been proposed as a mechanism of myocardial damage and dysfunction. Glucagon-like peptide-1 (GLP-1) has been shown to improve heart recovery and function after ischemia and to promote cell survival. The protective effects of GLP-1 on oxidative stress-induced apoptosis were investigated in human CPCs isolated from human heart biopsies. Mesenchymal-type cells were isolated from human heart biopsies, exhibited the marker profile of CPCs, differentiated toward the myocardiocyte, adipocyte, chondrocyte, and osteocyte lineages under appropriate culture conditions, and expressed functional GLP-1 receptors. CPCs were incubated with GLP-1 with or without hydrogen peroxide (H(2)O(2)). Phospho- and total proteins were detected by immunoblotting and immunofluorescence analysis. Gene expression was evaluated by quantitative RT-PCR. The role of the canonical GLP-1 receptor was assessed by using the receptor antagonist exendin(9-39) and receptor-specific silencer small interfering RNAs. Cell apoptosis was quantified by an ELISA assay and by flow cytometry-detected Annexin V. Exposure of CPCs to H(2)O(2) induced a 2-fold increase in cell apoptosis, mediated by activation of the c-Jun N-terminal protein kinase (JNK) pathway. Preincubation of CPCs with GLP-1 avoided H(2)O(2)-triggered JNK phosphorylation and nuclear localization, and protected CPCs from apoptosis. The GLP-1 effects were markedly reduced by coincubation with the receptor antagonist exendin(9-39), small interfering RNA-mediated silencing of the GLP-1 receptor, and pretreatment with the protein kinase A inhibitor H89. In conclusion, activation of GLP-1 receptors prevents oxidative stress-mediated apoptosis in human CPCs by interfering with JNK activation and may represent an important mechanism for the cardioprotective effects of GLP-1.

Insulin is a major endocrine hormone also involved in the regulation of energy and lipid metabolism via the activation of an intracellular signaling cascade involving the insulin receptor (INSR), insulin receptor substrate (IRS) proteins, phosphoinositol 3-kinase (PI3K) and protein kinase B (AKT). Specifically, insulin regulates several aspects of the development and function of adipose tissue and stimulates the differentiation program of adipose cells. Insulin can activate its responses in adipose tissue through two INSR splicing variants: INSR-A, which is predominantly expressed in mesenchymal and less-differentiated cells and mainly linked to cell proliferation, and INSR-B, which is more expressed in terminally differentiated cells and coupled to metabolic effects. Recent findings have revealed that different distributions of INSR and an altered INSR-A:INSR-B ratio may contribute to metabolic abnormalities during the onset of insulin resistance and the progression to type 2 diabetes. In this review, we discuss the role of insulin and the INSR in the development and endocrine activity of adipose tissue and the pharmacological implications for the management of obesity and type 2 diabetes.

Diabetic foot is a common complication in diabetes mellitus course, able to increase the overall morbidity/mortality risk of such a disease. The aim was to investigate the outcomes, the incidence of clinical events, the number of recurrent ulcers in patients with diabetic foot during 1 year follow-up after angioplasty (PTA) revascularization. From January 2007 to August 2009, 103 diabetic patients with diabetic foot undergoing revascularization of a lower limb by PTA were recruited. At 1 year follow-up we assessed: "major" (death, stroke, Myocardial Infaction (MI) and "minor" (Deep Vein Thrombosis (DVT), renal failure, restenosis) events incidence; recurrent ulcers incidence; the predictive elements of all these events. At 1 year follow-up, "major"/"minor" events incidence was 15% (deaths:5, stroke: 1, MI: 9%) and 34% (renal failure: 11, DVT: 9, restenosis: 14%), respectively. Obesity, high low density level-cholesterol levels and distal arterial lesions (at posterior tibial artery in particular) were statistically significantly associated with major events (p<0.05); only obesity resulted statistically associated with minors (p = 0.043). High levels of C-reactive protein had a statistically significant relationship with the recurrence of ulcers (p = 0.006) while distal arterial obstructions showed a trend toward significance. To improve diabetic foot mortality and morbidity rate, our study underlines the importance of a prompt diagnosis and appropriate revascularization treatment. Other studies are needed to ascertain these. © 2012 Asian Network for Scientific Information.

Background and aim: The objective of this cross-sectional study was to evaluate the degree of glycaemic control and the frequency of diabetic complications in Italian people with diabetes who were treated with continuous subcutaneous insulin infusion (CSII). Methods and results: Questionnaires investigating the organisation of diabetes care centres, individuals’ clinical and metabolic features and pump technology and its management were sent to adult and paediatric diabetes centres that use CSII for treatment in Italy. Information on standard clinical variables, demographic data and acute and chronic diabetic complications was derived from local clinical management systems. The sample consisted of 6623 people with diabetes, which was obtained from 93 centres. Of them, 98.8% had type 1 diabetes mellitus, 57.2% were female, 64% used a conventional insulin pump and 36% used a sensor-augmented insulin pump. The median glycated haemoglobin (HbA1c) level was 60 mmol/mol (7.6%). The HbA1c target (i.e. <58 mmol/mol for age <18 years and <53 mmol/mol for age >18 years) was achieved in 43.4% of paediatric and 23% of adult participants. Factors such as advanced pump functions, higher rate of sensor use, pregnancy in the year before the study and longer duration of diabetes were associated with lower HbA1c levels. The most common chronic complications occurring in diabetes were retinopathy, microalbuminuria and hypertension. In the year before the study, 5% of participants reported ≥1 episode of severe hypoglycaemic (SH) episodes (SH) and 2.6% reported ≥1 episode of ketoacidosis. Conclusions: Advanced personal skills and use of sensor-based pump are associated with better metabolic control outcomes in Italian people with diabetes who were treated with CSII. The reduction in SH episodes confirms the positive effect of CSII on hypoglycaemia. Clinical trial registration number: NCT 02620917 (ClinicalTrials.gov). © 2017 The Italian Society of Diabetology, the Italian Society for the Study of Atherosclerosis, the Italian Society of Human Nutrition, and the Department of Clinical Medicine and Surgery, Federico II University

Type 2 diabetes mellitus is increasing in prevalence at alarming rates. Concurrent with its expanding prevalence is the increase in the related risk of morbidity and mortality. Because diabetic patients are prone to cardiovascular disease, treatment strategies should address the cardiovascular risk factors, including blood pressure, lipids, and body weight, in addition to the glycemic aspects of the disease. Newer agents, such as glucagon-like peptide-1 (GLP-1) analogs and dipeptidyl peptidase-4 (DPP-4) inhibitors, have varying degrees of evidence to support their effects on body weight, blood pressure, and lipid levels, beyond glycated hemoglobin reduction. While GLP-1 agonists produce a weight loss, the DPP-4 inhibitors, conversely, appear to have a weight-neutral effect. Substantial evidence demonstrates that both medications produce modest reductions in systolic blood pressure and, in some cases, diastolic blood pressure, and reduce several markers of cardiovascular risk, including C-reactive protein. Moreover, GLP-1 influences endothelial function. The effect of the incretin hormones on serum lipids are either neutral or beneficial, with small, non-significant decreases in LDL cholesterol, increases in HDL cholesterol, and occasionally significant decreases in fasting triglyceride levels. Also, they have positive effects on hepatic steatosis. Although GLP-1 agonists and DPP-4 inhibitors are at present not appropriate for primary treatment of cardiovascular risks factors, the reduction of these parameters is evidently beneficial.

AIMS: Postprandial hyperglycaemia in patients with Type 2 diabetes mellitus has been linked to the development of cardiovascular disease. This study compared the effects of mealtime (thrice-daily) nateglinide with once-daily glyburide on postprandial glucose levels in patients with Type 2 diabetes and postprandial hyperglycaemia. METHODS: Patients with Type 2 diabetes aged ≥ 21 years with 2-h postprandial glucose levels ≥ 11.1 mmol/l, HbA(1c) of 6.5-8.5% (48-69 mmol/mol) and BMI of 22-30 kg/m(2) were randomized to 6 weeks' double-blind treatment with nateglinide 120 mg three times daily prior to meals, or glyburide 5 mg once daily before breakfast. The primary endpoint was the baseline-adjusted change in plasma glucose from preprandial (fasting plasma glucose) to 2-h postprandial glucose levels (2-h postprandial glucose excursion) at 6 weeks. RESULTS: Patients were randomized to nateglinide (n = 122) or glyburide (n = 110). The treatment groups were similar in terms of age, gender, BMI, fasting plasma glucose, 2-h postprandial glucose and HbA(1c). At endpoint, nateglinide recipients had significantly greater reductions than those receiving glyburide in both the 2-h (-2.4 vs. -1.6 mmol/l; P = 0.02) and 1-h (-1.7 vs. -0.9 mmol/l; P = 0.016) postprandial glucose excursions. Adverse events, most commonly symptomatic hypoglycaemia, were reported in 26% of recipients of glyburide and 22% of recipients of nateglinide. Episodes of suspected mild hypoglycaemia were reported in 24% of recipients of glyburide and 10% of recipients of nateglinide. CONCLUSIONS: Nateglinide leads to greater reductions in postprandial glucose excursions and is associated with a lower risk of hypoglycaemia than glyburide in this selected population of patients with Type 2 diabetes.

p66Shc, a 66 kDa proto-oncogene Src collagen homologue (Shc) adaptor protein, is classically known as a signalling protein implicated in receptor tyrosine kinase signal transduction. The p66Shc isoform exerts a physiologically relevant, inhibitory signalling effect on the Erk pathway in skeletal muscle myoblasts, which is necessary for actin cytoskeleton polymerization and normal glucose transport responses. More recently, p66Shc has been also identified as a sensor of oxidative stress-induced apoptosis and as a longevity protein in mammals, actions which require Ser36 phosphorylation of the protein and consequent accumulation of intracellular reactive oxygen species. Oxidative stress plays a key role in dysfunction of several organs and tissues, and this is of interest in metabolic diseases such as type 2 diabetes. Thus changes in p66Shc expression and/or function may play an important role in the pathogenesis of type 2 diabetes and potentially serve as an effective target for its treatment.

OBJECTIVE: In type 2 diabetes, prevalence of nonalbuminuric renal impairment is increasing worldwide, though its clinical significance remains unclear. This large-cohort study aimed at evaluating the association of this phenotype with cardiovascular risk factors and other complications. METHODS: Type 2 diabetic patients from the Renal Insufficiency And Cardiovascular Events (RIACE) Italian Multicenter Study (n = 15,773), visiting consecutively 19 hospital-based Diabetes Clinics in years 2007-2008, were examined. Serum creatinine was assessed by the Jaffe method; albuminuria was measured by immunonephelometry or immunoturbidimetry. RESULTS: Of patients with renal impairment, as identified by an estimated glomerular filtration rate (eGFR) less than 60 ml/min per 1.73 m², 56.6% were normoalbuminuric, 30.8% were microalbuminuric, and 12.6% were macroalbuminuric. Percentages were similar when GFR was estimated using the more accurate Chronic Kidney Disease Epidemiology Collaboration equation instead of the simplified Modification of Diet in Renal Disease formula, and were independent of age, thus indicating that the increasing prevalence of this phenotype does not reflects misclassification of elderly patients. Nonalbuminuric renal impairment was not associated with HbA(1c) and correlated less strongly with retinopathy and hypertension than albuminuria, either alone or associated with reduced eGFR. It was associated with a higher prevalence of cardiovascular disease (CVD) than albuminuria alone, but lower than albuminuric renal impairment. Female sex correlated with nonalbuminuric renal impairment and male sex with the albuminuric forms. CONCLUSIONS: These data show that type 2 diabetic patients with nonalbuminuric renal impairment exhibit distinct clinical features, suggesting predominance of macroangiopathy as underlying renal pathology, and that this phenotype is associated with significant CVD burden.

The small ubiquitin-like modifier-conjugating enzyme UBC9, involved in protein modification through covalent attachment of small ubiquitin-like modifier and other less defined mechanisms, has emerged as a key regulator of cell proliferation and differentiation. To explore the role of UBC9 in adipocyte differentiation, the UBC9 protein levels were examined in differentiating 3T3-L1 cells. UBC9 mRNA and protein levels were increased 2.5-fold at d 2 and then gradually declined to basal levels at d 8 of differentiation. In addition, UBC9 was expressed predominantly in the nucleus of preadipocytes but shifted to cytoplasmic compartments after d 4, after induction of differentiation. UBC9 knockdown was then achieved in differentiating 3T3-L1 preadipocytes using a specific small interfering RNA. Oil-Red-O staining demonstrated accumulation of large triglyceride droplets in approximately 90% of control cells, whereas lipid droplets were smaller and evident in only 30% of cells treated with the UBC9-specific small interfering RNA. CCAAT/enhancer-binding protein (C/EBP)-δ, peroxisome proliferator-activated receptor-γ, and C/EBPα mRNA levels were increased severalfold 2-6 d after induction of differentiation in control cells, whereas the expression of these transcription factors was significantly lower in the presence of UBC9 gene silencing. Adenovirus-mediated overexpression of a catalytically inactive mutant UBC9 protein in 3T3-L1 cells resulted in no changes in expression of adipogenic transcription factors and conversion to mature adipocytes as compared with control. In conclusion, UBC9 appears to play an important role in adipogenesis. The temporal profile of UBC9 induction and its ability to affect C/EBPδ mRNA induction support a role for this protein during early adipogenesis.

CONTEXT AND OBJECTIVE: High-mobility group box-1 (HMGB1) is a pro-inflammatory cytokine that may contribute to the pathogenesis of micro- and macrovascular complications commonly observed in diabetes. We investigated whether HMGB1 is associated with: i) markers of low-grade inflammation (LGI) and endothelial dysfunction (ED) and pulse pressure (PP, a marker of arterial stiffness); ii) prevalent nephropathy, retinopathy and cardiovascular disease (CVD) in type 1 diabetes; and iii) the potential mediating roles of LGI, ED and PP therein. DESIGN AND METHODS: This was a cross-sectional nested case-control study of 463 patients (226 women; mean age 40±10 years) with type 1 diabetes from the EURODIAB Prospective Complications Study. We used linear and binary or multinomial logistic regression analyses adjusted for traditional risk factors. RESULTS: Serum Ln-HMGB1 levels were positively associated with LGI and ED (standardised β=0.07 (95% confidence interval (CI): 0.02-0.12) and β=0.08 (95% CI: 0.02-0.14) respectively), but not with PP. Higher Ln-HMGB1 (per unit) was associated with greater odds of micro- and macroalbuminuria: odds ratio (OR)=1.24 (95% CI: 0.90-1.71) and OR=1.61 (95% CI: 1.15-2.25) respectively, P for trend=0.004. Further adjustments for LGI or ED did not attenuate these associations. No such associations were found between Ln-HMGB1 and estimated glomerular filtration rate (eGFR), retinopathy or CVD, however. CONCLUSIONS: In type 1 diabetes, higher serum HMGB1 levels are associated with greater prevalence and severity of albuminuria, though not with eGFR, retinopathy and CVD. Prospective studies are needed to clarify the causal role of HMGB1, if any, in the pathogenesis of vascular complications in type 1 diabetes.

The widespread increase in life expectancy is accompanied by an increased prevalence of features of physical frailty. Signs and symptoms may include sarcopenia and osteopenia, reduced exercise capacity, and diminished sense of well-being. The pathogenesis of age-associated sarcopenia and osteopenia is multifactorial, and hormonal decline may be a contributing factor. Aging is associated with a progressive decrease in GH secretion, and more than 30% of elderly people have circulating IGF1 levels below the normal range found in the young. GH acts directly on target tissues, including skeletal muscle and bone among many others, but many effects are mediated indirectly by circulating (liver-derived) or locally produced IGF1. Aging is also associated with reduced insulin sensitivity which, in turn, may contribute to the impairment of IGF1 action. Recent experimental evidence suggests that besides the age-dependent decline in GH and IGF1 serum levels, the dysregulation of GH and IGF1 actions due to impairment of the post-receptor signaling machinery may contribute to the loss of muscle mass and osteopenia. This article will focus on the molecular mechanisms of impaired GH and IGF1 signaling and action in aging, and their role in the pathogenesis of sarcopenia and osteoporosis.

The p66(Shc) protein mediates oxidative stress-related injury in multiple tissues. Steatohepatitis is characterized by enhanced oxidative stress-mediated cell damage. The role of p66(Shc) in redox signaling was investigated in human liver cells and alcoholic steatohepatitis. HepG2 cells with overexpression of wild-type or mutant p66(Shc), with Ser(36) replacement by Ala, were obtained through infection with recombinant adenoviruses. Reactive oxygen species and oxidation-dependent DNA damage were assessed by measuring dihydroethidium oxidation and 8-hydroxy-2'-deoxyguanosine accumulation into DNA, respectively. mRNA and protein levels of signaling intermediates were evaluated in HepG2 cells and liver biopsies from control and alcoholic steatohepatitis subjects. Exposure to H2O2 increased reactive oxygen species and phosphorylation of p66(Shc) on Ser(36) in HepG2 cells. Overexpression of p66(Shc) promoted reactive oxygen species synthesis and oxidation-dependent DNA damage, which were further enhanced by H2O2. p66(Shc) activation also resulted in increased Erk-1/2, Akt and FoxO3a phosphorylation. Blocking of Erk-1/2 activation inhibited p66(Shc) phosphorylation on Ser(36). Increased p66Shc expression was associated with reduced mRNA levels of anti-oxidant molecules, such as NF-E2-related factor 2 and its target genes. In contrast, overexpression of the phosphorylation defective p66(Shc) Ala(36) mutant inhibited p66(Shc) signaling, enhanced anti-oxidant genes, and suppressed reactive oxygen species and oxidation-dependent DNA damage. Increased p66(Shc) protein levels and Akt phosphorylation were observed in liver biopsies from alcoholic steatohepatitis compared to control subjects.

Endothelial cells participate in inflammatory events leading to atherogenesis by regulating endothelial cell permeability via the expression of VE-Cadherin and β-catenin and leukocyte recruitment via the expression of E-Selectins and other adhesion molecules. The protein p66(Shc) acts as a sensor/inducer of oxidative stress and may promote vascular dysfunction. The objective of this study was to investigate the role of p66(Shc) in tumor necrosis factor TNFα-induced E-Selectin expression and function in human umbilical vein endothelial cells (HUVEC). Exposure of HUVEC to 50 ng/ml TNFα resulted in increased leukocyte transmigration through the endothelial monolayer and E-Selectin expression, in association with augmented phosphorylation of both p66(Shc) on Ser(36) and the stress kinase c-Jun NH2-terminal protein kinase (JNK)-1/2, and higher intracellular reactive oxygen species (ROS) levels. Overexpression of p66(Shc) in HUVEC resulted in enhanced p66(Shc) phosphorylation on Ser(36), increased ROS and E-Selectin levels, and amplified endothelial cell permeability and leukocyte transmigration through the HUVEC monolayer. Conversely, overexpression of a phosphorylation-defective p66(Shc) protein, in which Ser(36) was replaced by Ala, did not augment ROS and E-Selectin levels, nor modify cell permeability or leukocyte transmigration beyond those found in wild-type cells. Moreover, siRNA-mediated silencing of p66(Shc) resulted in marked reduction of E-Selectin expression and leukocyte transmigration. In conclusion, p66(Shc) acts as a novel intermediate in the TNFα pathway mediating endothelial dysfunction, and its action requires JNK-dependent phosphorylation of p66(Shc) on Ser(36).