Description: The frictional resistance on a fault during slip controls earthquake dynamics. Friction dissipates heat during an earthquake; therefore, the fault temperature after an earthquake provides insight into the level of friction. The Japan Trench Fast Drilling Project (Integrated Ocean Drilling Program Expedition 343 and 343T) installed a borehole temperature observatory 16 months after the March 2011 moment magnitude 9.0 Tohoku-Oki earthquake across the fault where slip was ~50 meters near the trench. After 9 months of operation, the complete sensor string was recovered. A 0.31°C temperature anomaly at the plate boundary fault corresponds to 27 megajoules per square meter of dissipated energy during the earthquake. The resulting apparent friction coefficient of 0.08 is considerably smaller than static values for most rocks.

Description: Biallelic inherited mutations in the oxidative DNA damage repair gene MUTYH predispose to colorectal adenomas and colorectal carcinoma (CRC) with high penetrance. We investigated whether rare inherited variants in other oxidative DNA damage repair genes predisposed to CRC. Single marker association analyses were assessed under an allelic model with Bonferroni correction for multiple testing. All statistical tests were two-sided. A rare inherited nonsynonymous variant in OGG1 (Gly308Glu), the functional partner of MUTYH, was over-represented in case patients with advanced CRC compared with population-based control subjects (n = 36 of 2142 case patients vs n = 15 of 2175 control subjects in the training phase, P = 1.8 x 10 –3 ; and n = 22 of 1005 case patients vs n = 8 of 1389 control subjects in the validation phase, P = 4.8 x 10 –4 ; P = 1.4 x 10 –5 combined; odds ratio = 2.92, 95% confidence interval = 1.80 to 4.74). Glycine at residue 308 was highly conserved through evolution, and the glutamic acid substitution was predicted as likely to interfere with function. Biallelic inherited and somatic OGG1 mutations were rarely observed in OGG1 Gly308Glu carriers, nor did we find any associated somatic mutator phenotype. These data suggest that OGG1 Gly308Glu may act as a low-penetrance allele that contributes to colorectal tumorigenesis.

Description: APOBEC3A (A3A) is a myeloid lineage-specific DNA cytosine deaminase with a role in innate immunity to foreign DNA. Previous studies have shown that heterologously expressed A3A is genotoxic, suggesting that monocytes may have a mechanism to regulate this enzyme. Indeed, we observed no significant cytotoxicity when interferon was used to induce the expression of endogenous A3A in CD14+-enriched primary cells or the monocytic cell line THP-1. In contrast, doxycycline-induced A3A in HEK293 cells caused major cytotoxicity at protein levels lower than those observed when CD14+ cells were stimulated with interferon. Immunofluorescent microscopy of interferon-stimulated CD14+ and THP-1 cells revealed that endogenous A3A is cytoplasmic, in stark contrast to stably or transiently transfected A3A, which has a cell-wide localization. A3A constructs engineered to be cytoplasmic are also nontoxic in HEK293 cells. These data combine to suggest that monocytic cells use a cytoplasmic retention mechanism to control A3A and avert genotoxicity during innate immune responses.

Description: Leptin receptors (ObRs) in the forebrain and hindbrain have been independently recognized as important mediators of leptin responses. It is unclear how leptin activity in these areas is integrated. We tested whether both forebrain and hindbrain ObRs have to be activated simultaneously to change energy balance and to maintain metabolic homeostasis. Previous studies used acute leptin injections in either the third ventricle (1–5 μg) or the fourth ventricle (3–10 μg); here we used 12-day infusions of low doses of leptin in one or both ventricles (0.1 μg/24 h in third, 0.6 μg/24 h in fourth). Male Sprague Dawley rats were fitted with third and fourth ventricle cannulas, and saline or leptin was infused from Alzet pumps for 6 or 12 days. Rats that received leptin into only the third or the fourth ventricle were not different from controls that received saline in both ventricles. By contrast, rats with low-dose leptin infusions into both the third and fourth ventricle showed a dramatic 60% reduction in food intake that was reversed on day 6, a 20% weight loss that stabilized on day 6, and a 50% decrease in body fat at day 12 despite the correction of food intake. They displayed normal activity and maintained energy expenditure despite weight loss, indicating inappropriately high thermogenesis that coincided with increased signal transducer and activator of transcription 3 (STAT3) phosphorylation in the brainstem. Altogether, these findings show that with low doses of leptin, chronic activation of both hypothalamic and brainstem ObRs is required to reduce body fat.

Description: APOBEC3G has an important role in human defense against retroviral pathogens, including HIV-1. Its single-stranded DNA cytosine deaminase activity, located in its C-terminal domain (A3Gctd), can mutate viral cDNA and restrict infectivity. We used time-resolved nuclear magnetic resonance (NMR) spectroscopy to determine kinetic parameters of A3Gctd's deamination reactions within a 5'-CCC hot spot sequence. A3Gctd exhibited a 45-fold preference for 5'-CCC substrate over 5'-CCU substrate, which explains why A3G displays almost no processivity within a 5'-CCC motif. In addition, A3Gctd's shortest substrate sequence was found to be a pentanucleotide containing 5'-CCC flanked on both sides by a single nucleotide. A3Gctd as well as full-length A3G showed peak deamination velocities at pH 5.5. We found that H216 is responsible for this pH dependence, suggesting that protonation of H216 could play a key role in substrate binding. Protonation of H216 appeared important for HIV-1 restriction activity as well, since substitutions of H216 resulted in lower restriction in vivo .

Description: Aquaporin 11 (AQP11) is a newly described member of the protein family of transport channels. AQP11 associates with the endoplasmic reticulum (ER) and is highly expressed in proximal tubular epithelial cells in the kidney. Previously, we identified and characterized a recessive mutation of the highly conserved Cys227 to Ser227 in mouse AQP11 that caused proximal tubule (PT) injury and kidney failure in mutant mice. The current study revealed induction of ER stress, unfolded protein response, and apoptosis as molecular mechanisms of this PT injury. Cys227Ser mutation interfered with maintenance of AQP11 oligomeric structure. AQP11 is abundantly expressed in the S1 PT segment, a site of major renal glucose flux, and Aqp11 mutant mice developed PT-specific mitochondrial injury. Glucose increased AQP11 protein expression in wild-type kidney and upregulation of AQP11 expression by glucose in vitro was prevented by phlorizin, an inhibitor of sodium-dependent glucose transport across PT. Total AQP11 levels in heterozygotes were higher than in wild-type mice but were not further increased in response to glucose. In Aqp11 insufficient PT cells, glucose potentiated increases in reactive oxygen species (ROS) production. ROS production was also elevated in Aqp11 mutation carriers. Phenotypically normal mice heterozygous for the Aqp11 mutation repeatedly treated with glucose showed increased blood urea nitrogen levels that were prevented by the antioxidant sulforaphane or by phlorizin. Our results indicate an important role for AQP11 to prevent glucose-induced oxidative stress in proximal tubules.

Description: The renin-angiotensin system (RAS) may alter cardiac energy metabolism in heart failure. Angiotensin II (ANG II), the main effector of the RAS in heart failure, has emerged as an important regulator of cardiac hypertrophy and energy metabolism. We studied the metabolic perturbations and insulin response in an ANG II-induced hypertrophy model. Ex vivo heart perfusion showed that hearts from ANG II-treated mice had a lower response to insulin with significantly reduced rates of glucose oxidation in association with increased pyruvate dehydrogenase kinase 4 (PDK4) levels. Palmitate oxidation rates were significantly reduced in response to insulin in vehicle-treated hearts but remained unaltered in ANG II-treated hearts. Furthermore, phosphorylation of Akt was also less response to insulin in ANG II-treated wild-type (WT) mice, suggestive of insulin resistance. We evaluated the role of PDK4 in the ANG II-induced pathology and showed that deletion of PDK4 prevented ANG II-induced diastolic dysfunction and normalized glucose oxidation to basal levels. ANG II-induced reduction in the levels of the deacetylase, SIRT3, was associated with increased acetylation of pyruvate dehydrogenase (PDH) and a reduced PDH activity. In conclusion, our findings show that a combination of insulin resistance and decrease in PDH activity are involved in ANG II-induced reduction in glucose oxidation, resulting in cardiac inefficiency. ANG II reduces PDH activity via acetylation of PDH complex, as well as increased phosphorylation in response to increased PDK4 levels.

Description: Testosterone level is low in insulin-resistant type 2 diabetes. Whether this is due to negative effects of high level of insulin on the testes caused by insulin resistance has not been studied in detail. In this study, we found that insulin directly binds to insulin receptors in Leydig cell membranes and activates phospho-insulin receptor-β (phospho-IR-β), phospho-IRS1, and phospho-AKT, leading to up-regulation of DAX-1 (dosage-sensitive sex reversal, adrenal hypoplasia critical region, on chromosome X, gene 1) gene expression in the MA-10 mouse Leydig cell line. Insulin also inhibits cAMP-induced and liver receptor homolog-1 (LRH-1)-induced steroidogenic enzyme gene expression and steroidogenesis. In contrast, knockdown of DAX-1 reversed insulin-mediated inhibition of steroidogenesis. Whether insulin directly represses steroidogenesis through regulation of steroidogenic enzyme gene expression was assessed in insulin-injected mouse models and high fat diet-induced obesity. In insulin-injected mouse models, insulin receptor signal pathway was activated and subsequently inhibited steroidogenesis via induction of DAX-1 without significant change of luteinizing hormone or FSH levels. Likewise, the levels of steroidogenic enzyme gene expression and steroidogenesis were low, but interestingly, the level of DAX-1 was high in the testes of high fat diet-fed mice. These results represent a novel regulatory mechanism of steroidogenesis in Leydig cells. Insulin-mediated induction of DAX-1 in Leydig cells of testis may be a key regulatory step of serum sex hormone level in insulin-resistant states.

Description: Purpose: To study the somatic molecular profile of the EGF receptor (EGFR) pathway in advanced colorectal cancer, its relationship to prognosis, the site of the primary and metastases, and response to cetuximab. Experimental Design: We used Sequenom and Pyrosequencing for high-throughput somatic profiling of the EGFR pathway in 1,976 tumors from patients with advanced colorectal cancer from the COIN trial (oxaliplatin and fluoropyrimidine chemotherapy ± cetuximab). Correlations between mutations, clinicopathologic, response, and survival data were carried out. Results: Sequenom and Pyrosequencing had 99.0% (9,961/10,063) genotype concordance. We identified 13 different KRAS mutations in 42.3% of advanced colorectal cancers, 2 BRAF mutations in 9.0%, 4 NRAS mutations in 3.6%, and 5 PIK3CA mutations in 12.7%. 4.2% of advanced colorectal cancers had microsatellite instability (MSI). KRAS and PIK3CA exon 9, but not exon 20, mutations cooccurred ( P = 8.9 x 10 –4 ) as did MSI and BRAF mutations ( P = 5.3 x 10 –10 ). KRAS mutations were associated with right colon cancers ( P = 5.2 x 10 –5 ) and BRAF mutations with right ( P = 7.2 x 10 –5 ) and transverse colon ( P = 9.8 x 10 –6 ) cancers. KRAS mutations were associated with lung-only metastases ( P = 2.3 x 10 –4 ), BRAF mutations with peritoneal ( P = 9.2 x 10 –4 ) and nodal-only ( P = 3.7 x 10 –5 ) metastases, and MSI ( BRAF WT ) with nodal-only metastases ( P = 2.9 x 10 –4 ). MSI ( BRAF WT ) was associated with worse survival (HR = 1.89, 95% CI 1.30–2.76, P = 8.5 x 10 –4 ). No mutations, subsets of mutations, or MSI status were associated with response to cetuximab. Conclusions: Our data support a functional cooperation between KRAS and PIK3CA in colorectal tumorigenesis and link somatic profiles to the sites of metastases. MSI was associated with poor prognosis in advanced disease, and no individual somatic profile was associated with response to cetuximab in COIN. Clin Cancer Res; 19(15); 4104–13. ©2013 AACR .

Description: Background Subtypes of glioblastoma multiforme (GBM) based on genetic and molecular alterations are thought to cause alterations in anatomic MRI owing to downstream biological changes, such as edema production, blood–brain barrier breakdown, and necrosis. The purpose of the current study was to identify a potential relationship between imaging features and the mesenchymal (MES) GBM subtype, which has the worst patient prognosis. Methods MRIs from 46 patients with histologically confirmed GBM were retrospectively analyzed. The volume of contrast enhancement, regions of central necrosis, and hyperintensity of T2/fluid attenuated inversion recovery (FLAIR) were measured. Additionally, the ratio of T2/FLAIR hyperintense volume to the volume of contrast enhancement and necrosis was calculated. Results The volume of contrast enhancement, volume of central necrosis, combined volume of contrast enhancement and central necrosis, and the ratio of T2/FLAIR to contrast enhancement and necrosis were significantly different in MES compared with non-MES GBM (Mann–Whitney, P 〈 .05). Receiver-operator characteristics indicated that these 4 metrics were all significant predictors of the MES phenotype. The volume ratio of T2 hyperintensity to contrast enhancement and central necrosis was significantly lower in MES vs non-MES GBM ( P 〈 .0001), was a significant predictor of the MES phenotype (area under the curve = 0.93, P 〈 .001), and could be used to stratify short- and long-term overall survival (log-rank, P = .0064 using cutoff of 3.0). These trends were also present when excluding isocitrate dehydrogenase 1 mutant tumors and incorporating covariates such as age and KPS score. Conclusions Results suggest that volume ratio may be a simple, cost-effective, and noninvasive biomarker for quickly identifying MES GBM.