Citations

Leucine (Leu) is the most potent branched‐chain amino acid that selectively enhances protein synthesis via intracellular signaling pathways. Since protein synthesis is an energy consuming process, we hypothesized that Leu may enhance mitochondrial biogenesis and functions. We determined the effect of Leu at mitochondrial mRNA levels, enzyme activities, and ATP production rate (MAPR) in cultured human liver cell line THLE‐3. Cells were pre‐incubated in a low‐Leu (0.1mM), serum‐free media for 24 hours and gene transcript profiles were measured using Affymetrix HG‐U133A GeneChips at 0, 30, 60, 120 and 480 minutes after increasing the Leu concentrations from to 2.0 mM. Thirty mitochondrial gene transcripts, both mitochondrial DNA and nuclear‐encoded, were significantly increased at various time points with treatment of higher concentrations of Leu. The mRNA levels of 6 mitochondrial genes including two ATP synthase, cytochrome P450, cytochrome C oxidase III, and NADH dehydrogenase 4 were confirmed by real‐time PCR measurements. Western blot analysis showed that 8 hours of high concentrations of Leu increased protein levels of key mitochondrial proteins, citrate synthase and cytochrome c oxidase I, by 42% and 20% respectively. In addition, the enzyme activity of citrate synthase was significantly increased by 25%, and MAPR by 30–40% using various substrates after 8 hours of high Leu. In conclusion, Leu stimulated mitochondrial biogenesis and oxidative phosphorylation in liver cells. This work is supported by NIH grants T32 DK7352, and RO1 DK41972.

Acute exercise appears to have positive influence on arterial function during the recovery period, yet the effect of obesity is poorly understood in recovery. We examined the effects of an acute bout of exercise on arterial function in obese versus healthy weight individuals. Young (23 yr), lean (n=38, BMI=22.3 kg/m 2 ) and obese (n=20, BMI=34.0 kg/m 2 ) individuals had arterial measurements obtained at rest, and 15 and 30 min following a maximal bout of aerobic exercise. Arterial tonometry and ultrasound were used to obtain central BP, arterial compliance and stiffness (beta stiffness, elastic modulus (Ep), and central pulse wave velocity (PWV)). Despite similar central mean BP, the obese group had higher cPWV following exercise. Beta stiffness and Ep responded similarly to exercise between groups. Arterial compliance was higher in obese but the response in recovery was similar between groups. Lean Obese Pre 15‐min post 30‐min post Pre 15‐min post 30‐min post Mean aortic BP 82 83 82 87 86 87 Central PWV 5.67 5.46 5.35 5.84 6.11 6.16 Beta Stiffness 5.89 6.34 5.78 4.88 6.04 5.31 Elastic Modulus 69 75 67 67 78 66 In this young cohort, obesity was associated with increased central arterial stiffness, independent of BP, but higher arterial compliance. This suggests that measures of arterial stiffness provide differential information potentially associated with where in the arterial tree measures were made.

The importance of normal circadian rhythms is underscored by the known relationship between circadian disruption and increased cancer risk. The goal of the present study was to investigate the role of the circadian clock in the regulation of genes encoding products that function in cellular transformation. Microarray analysis was used to evaluate changes in gene expression following siRNA‐mediated knockdown of the circadian clock protein Per 1 in a murine renal collecting duct cell line (mpkCCD c14 ). Several hundred genes underwent significant changes in expression following Per1 knockdown, including 21 genes involved in cellular transformation. Cdkn1a and Cyclin E1, both cell cycle regulators, claudin 1 and 12, involved in tight junction formation, and sFRP1, a regulator of Wnt signaling and a tumor suppressor in renal cell carcinoma, were all confirmed as novel Per1 target genes. In an independent sample set, Cdkn1a, Cyclin E1, Claudin 1 and 12, and sFRP1 were all up‐regulated following Per1 knockdown in mpkCCD c14 cells. The chromophobe subtype of renal cell carcinoma is thought to arise from the collecting duct. Interestingly, dysregulation of the circadian clock genes Per2 and Cry2 was observed in patient chromophobe tumor samples compared to normal tissues. These observations support a role for the circadian clock in the control of cellular transformation in the kidney.

The mechanisms underlying E‐cadherin clustering and AJ maturation are not fully understood although the E‐cadherin‐mediated formation of adherens junctions (AJs) is essential for the morphogenesis of epithelial cells. Here we report that the association between type Iγ phosphatidylinositol phosphate kinase (PIPKIγ) and Exo70 regulated the transport and clustering of Ecadherin on the plasma membrane and, subsequently, the extension of nascent E‐cadherin adhesions. We also observed that PI4,5P(2) accumulation at E‐cadherin clusters during the assembly of E‐cadherin adhesions. PIPKIγ‐generated PI4,5P(2) is required for recruiting Exo70 to newly formed E‐cadherin junctions and facilitates the assembly and maturation of AJs. Additionally, Rho activity and actin structure were impaired by loss of Exo70 and/or PIPKIγ. These results support a model in which PIPKIγ and PIPKIγ‐generated PI4,5P(2) pools at nascent E‐cadherin contacts cue Exo70 targeting and orients the tethering of exocyst‐associated E‐cadherin. This could be an important mechanism that regulates E‐cadherin clustering and AJ maturation, and actin reorganization, which is essential for the establishment of solid, polarized epithelial structures.

Acute systemic induced inflammation negatively affects arterial function in young healthy adults. An acute bout of aerobic exercise reduces arterial stiffness and improves endothelial function. Therefore, we evaluated endothelial function and wave reflection in older adults in response to acute systemic inflammation and the effect of moderate intensity endurance exercise immediately prior to induced inflammation. 59 healthy volunteers (range 55 – 75 years) were randomly allocated to an exercise or control group. Arterial function and inflammatory markers were measured at baseline, 24 h and 48 h after influenza vaccine and sham injections. CRP increased approximately 1.5 times, 24 and 48 h after vaccination while IL‐6 increased 24 hours after vaccination compared to the sham injection. Unexpectedly, arterial function was unaltered (Table). Inflammation and endothelial function were dissociated following vaccine‐induced acute systemic inflammation in older adults. Acute exercise prior to vaccination had no effect of inflammation or vascular function. Support: AHA #10PRE3500083 (SMR).

Introduction Heart rate variability (HRV), blood pressure variability (BPV) and baroreflex sensitivity (BRS), measures of autonomic nervous system function, are associated with cardiovascular (CV) outcome. African Americans (AA) have an increased prevalence of CV disorders in comparison to Caucasians (C). Purpose To determine race specific responses in BPV, BRS and HRV before and after maximal exercise. Methods 37 AA and 37 C (24 years) underwent maximal exercise on a cycle ergometer. BPV, BRS and HRV measurements were assessed using finger plethysmography before and after exercise. Data were log transformed and pre‐and post‐max test values were compared by race. Results Acute exercise significantly decreased BRS, LF‐HRV and HF‐HRV and significantly increased LF/HF‐HRV in both AA and C. With exercise, C significantly decreased measures of BRS and HRV more compared to AA; BRS‐SAPRRI transfer mean (C: 2.65±.54 to 1.09±.81 versus AA: 2.70±.40 to 1.70±.92), BRS‐down down (C: 3.21±.55 to 1.74±.49 versus AA: 3.28±1.0 to 2.2±.71), HRV‐LF (C: 6.39±.86 to 3.68±1.42 versus AA: 6.37±1.24 to 5.18±2.14) and HRV‐HF (C: 7.38±1.23 to 3.53±1.73 versus AA: 7.51±1.09 to 5.38±2.16). Conclusion C exhibited increased vagal withdrawal and greater reductions in BRS compared to AA in response to acute exercise. The impact of these racial differences in autonomic control on CV risk needs further investigation.

High‐fat diets induce changes in the gut microbiome and induce nonalcoholic fatty liver disease. This study tested the hypothesis that high‐fat feeding increases certain predominant hind gut bacteria in a C57BL/6 mouse model of obesity. We found that a high‐fat diet produced significant increases in both body weight and body fat percentage in C57BL/6 mice compared with a control group fed a low‐fat diet. With an immunohistochemical approach, we found that these changes were associated with increases in lipid droplets, inflammatory cell infiltration and inducible nitric oxide synthase (iNOS) level in the livers of mice fed the high‐fat diet. In addition, plasma leptin and tumor necrosis factor (TNFα) levels were elevated in mice fed the high‐fat diet, indicative of chronic inflammation. Eight out of twelve bacterial species that typically predominate hind gut microbial ecology were detected in fecal samples by DNA analysis. The DNA amount of one of these species, Lactobacillus (L.) acidophilus , was 6900‐fold greater in high‐fat fed mice compared to controls. L. acidophilus can promote inflammatory production of cytokines such as TNFα, which was also elevated in high‐fat fed mice. These results suggest that changes in the hindgut microbiome which accompany high fat feeding may contribute to the development of steatohepatitis in obese mice.

SPOP mutation disables 53BP1 ubiquitination and exclusion from DNA double-strand break sites and causes genome instability.