Noxious cold ion channel TRPA1 is activated by pungent compounds and bradykinin

Six members of the mammalian transient receptor potential (TRP) ion channels respond to varied temperature thresholds. The natural compounds capsaicin and menthol activate noxious heat-sensitive TRPV1 and cold-sensitive TRPM8, respectively. The burning and cooling perception of capsaicin and menthol demonstrate that these ion channels mediate thermosensation. We show that, in addition to noxious cold, pungent natural compounds present in cinnamon oil, wintergreen oil, clove oil, mustard oil, and ginger all activate TRPA1 (ANKTM1). Bradykinin, an inflammatory peptide acting through its G protein-coupled receptor, also activates TRPA1. We further show that phospholipase C is an important signaling component for TRPA1 activation. Cinnamaldehyde, the most specific TRPA1 activator, excites a subset of sensory neurons highly enriched in cold-sensitive neurons and elicits nociceptive behavior in mice. Collectively, these data demonstrate that TRPA1 activation elicits a painful sensation and provide a potential molecular model for why noxious cold can paradoxically be perceived as burning pain.     

Genome-wide association study in a Lebanese cohort confirms PHACTR1 as a major determinant of coronary artery stenosis

The manifestation of coronary artery disease (CAD) follows a well-choreographed series of events that includes damage of arterial endothelial cells and deposition of lipids in the sub-endothelial layers. Genome-wide association studies (GWAS) of multiple populations with distinctive genetic and lifestyle backgrounds are a crucial step in understanding global CAD pathophysiology. In this study, we report a GWAS on the genetic basis of arterial stenosis as measured by cardiac catheterization in a Lebanese population. The locus of the phosphatase and actin regulator 1 gene (PHACTR1) showed association with coronary stenosis in a discovery experiment with genome wide data in 1,949 individuals (rs9349379, OR?=?1.37, p?=?1.57×10(-5)). The association was replicated in an additional 2,547 individuals (OR?=?1.31, p?=?8.85×10(-6)), leading to genome-wide significant association in a combined analysis (OR?=?1.34, p?=?8.02×10(-10)). Results from this GWAS support a central role of PHACTR1 in CAD susceptibility irrespective of lifestyle and ethnic divergences. This association provides a plausible component for understanding molecular mechanisms involved in the formation of stenosis in cardiac vessels and a potential drug target against CAD.     

Highly sensitive measurement of lipid molecular species from biological samples by fluorimetric detection coupled to high-performance liquid chromatography

As the molecular species composition of glycerophospholipids provides more valuable information than the corresponding fatty acid composition, we have applied a fluorimetric detection (360 and 460 nm for excitation and emission wavelengths, respectively) of anthroyl derivatives of diradylglycerol species to minor phospholipid classes and subclasses from biological samples. Diacylglycerol species were obtained by phospholipase C treatment of phosphatidylcholine subclasses and phosphatidic acid extracted from rat thymocytes. Subpicomole measurements of molecular species from the minor subclass alkenylacylglycerophosphocholine could be achieved (e.g. 0.4 pmol of the 18:1/20:5 species). Such a sensitivity allowed study of the molecular species composition of another minor phospholipid, phosphatidic acid, and to evaluation of its alteration in mitogen-stimulated thymocytes as compared to unstimulated ones. Finally, we report that such a measurement is also applicable to other minor bioactive lipids with a hydroxyl group available, namely hydroxyeicosatetraenoates (HETEs), with a similar gain of sensitivity over conventional UV detection. Overall, these measurements, especially those of phospholipid molecular species, are sensitive, reliable and meaningful for precursor–product relationship between phospholipids.     

Docking interactions of the JNK scaffold protein WDR62

JNK (c-Jun N-terminal kinase) is part of a MAPK (mitogen-activated protein kinase) signalling cascade. Scaffold proteins simultaneously associate with various components of the MAPK signalling pathway and play a crucial role in signal transmission and MAPK regulation. WDR62 (WD repeat domain 62) is a JNK scaffold protein. Recessive mutations within WDR62 result in severe cerebral cortical malformation. In the present study we demonstrate the association of WDR62 with endogenous and overexpressed proteins of both JNK2 and the JNK2-activating kinase MKK7 (MAPK kinase 7). Association of WDR62 with JNK2 and MKK7 occurs via direct protein-protein interactions. We mapped the docking domain of WDR62 responsible for the association with JNK. WDR62 interacts with all JNK isoforms through a D domain motif located at the C-terminus. A WDR62 mutant lacking the putative JNK-binding domain fails to activate and recruit JNK to cellular granules. Furthermore, a synthetic peptide composed of the WDR62 docking domain inhibits JNK2 activity in vitro. WDR62 association with JNK2 requires both the JNK CD and ED domains, and the binding requisite is distinct from that of the previously described JNK2 association with JIP1 (JNK-interacting protein 1). Next, we characterized the association between WDR62 and MKK7. WDR62 associates directly with the MKK7β1 isoform independently of JNK binding, but fails to interact with MKK7α1. Furthermore, MKK7β1 recruits a protein phosphatase that dephosphorylates WDR62. Interestingly, a premature termination mutation in WDR62 that results in severe brain developmental defects does not abrogate WDR62 association with either JNK or MKK7. Therefore such mutations represent a loss of WDR62 function independent of JNK signalling.     

Role of human DNA polymerase κ in extension opposite from a cis-syn thymine dimer

Exposure of DNA to UV radiation causes covalent linkages between adjacent pyrimidines. The most common lesion found in DNA from these UV-induced linkages is the cis-syn cyclobutane pyrimidine dimer. Human DNA polymerase κ (Polκ), a member of the Y-family of DNA polymerases, is unable to insert nucleotides opposite the 3'T of a cis-syn T-T dimer, but it can efficiently extend from a nucleotide inserted opposite the 3'T of the dimer by another DNA polymerase. We present here the structure of human Polκ in the act of inserting a nucleotide opposite the 5'T of the cis-syn T-T dimer. The structure reveals a constrained active-site cleft that is unable to accommodate the 3'T of a cis-syn T-T dimer but is remarkably well adapted to accommodate the 5'T via Watson-Crick base pairing, in accord with a proposed role for Polκ in the extension reaction opposite from cyclobutane pyrimidine dimers in vivo.     

Abnormalities in arterial-ventricular coupling in older healthy persons are attenuated by sodium nitroprusside

The coupling between arterial elastance (E(A); net afterload) and left ventricular elastance (E(LV); pump performance), known as E(A)/E(LV), is a key determinant of cardiovascular performance and shifts during exercise due to a greater increase in E(LV) versus E(A). This normal exercise-induced reduction in E(A)/E(LV) decreases with advancing age. We hypothesized that sodium nitroprusside (SNP) can acutely ameliorate the age-associated deficits in E(A)/E(LV). At rest and during graded exercise to exhaustion, E(A) was characterized as end-systolic pressure/stroke volume and E(LV) as end-systolic pressure/end-systolic volume. Resting E(A)/E(LV) did not differ between old (70 ± 8 yr, n = 15) and young (30 ± 5 yr, n = 17) subjects because of a tandem increase in E(A) and E(LV) in older subjects. During peak exercise, a blunted increase in E(LV) in old (7.8 ± 3.1 mmHg/ml) versus young (11.4 ± 6.5 mmHg/ml) subjects blunted the normal exercise-induced decline in E(A)/E(LV) in old (0.25 ± 0.11) versus young (0.16 ± 0.05) subjects. SNP administration to older subjects lowered resting E(A)/E(LV) by 31% via a reduction in E(A) (10%) and an increase in E(LV) (47%) and lowered peak exercise E(A)/E(LV) (36%) via an increase in E(LV) (68%) without a change in E(A). Importantly, SNP attenuated the age-associated deficits in E(A)/E(LV) and E(LV) during exercise, and at peak exercise E(A)/E(LV) in older subjects on drug administration did not differ from young subjects without drug administration. In conclusion, some age-associated deficiencies in E(A)/E(LV), E(A), and E(LV), in older subjects can be acutely abolished by SNP infusion. This is relevant to common conditions in older subjects associated with a significant impairment of exercise performance such as frailty or heart failure with preserved ejection fraction.     

Applicability of mitochondrial DNA for the identification of Arvicolid species from faecal samples: a case study from the threatened Cabrera's vole

Arvicolid mitochondrial genomes evolve faster than in any other mammalian lineage. The genetic diversity exhibited by these rodents contrasts sharply with their phenotypic homogeneity. Furthermore, faecal droppings from Arvicolid rodents of similar body size are almost undistinguishable on the basis of pellet morphology and content. In this study, we advantaged from their high genetic diversity vs. phenotypic homogeneity to document the applicability of mtDNA extraction from vole droppings for latter identification of such via a rapid and efficient nested PCR‐based technique using the threatened Microtus cabrerae as a model species. We sequenced the mitochondrial control region from 75 individuals belonging to 11 species of Arvicolinae from Spain, Portugal, Greece and Italy, and an additional 19 sequences from ten Microtus species from other countries were downloaded from Genbank. Based on these control region sequences, we successfully designed and applied a nested PCR for M. cabrerae‐specific and arvicolid‐generic mtDNA markers to differentiate Cabrera’s vole faecal samples among other species of the Arvicolinae subfamily. Although this study used Cabrera’s vole as a model species, similar techniques based on mtDNA sequences may find a broader applicability for noninvasive genetic conservation of vole species and their populations.     

Overexpression of the HIF hydroxylases PHD1, PHD2, PHD3 and FIH are individually and collectively unfavorable prognosticators for NSCLC survival

Introduction

Hypoxia induced factors (HIFs) are at the heart of the adaptive mechanisms cancer cells must implement for survival. HIFs are regulated by four hydroxylases; Prolyl hydroxylase (PHD)-1,-2,-3 and factor inhibiting HIF (FIH). We aimed to investigate the prognostic impact of these oxygen sensors in NSCLC.

Methods

Tumor tissue samples from 335 resected stages I to IIIA NSCLC patients was obtained and tissue microarrays (TMAs) were constructed. Hydroxylase expression was evaluated by immunohistochemistry.

Principal Findings

There was scorable expression for all HIF hydroxylases in tumor cells, but not in stroma. In univariate analyses, high tumor cell expression of all the HIF hydroxylases were unfavorable prognosticators for disease-specific survival (DSS); PHD1 (P = 0.023), PHD2 (P = 0.013), PHD3 (P = 0.018) and FIH (P = 0.033). In the multivariate analyses we found high tumor cell expression of PHD2 (HR = 2.03, CI 95% 1.20–3.42, P = 0.008) and PHD1 (HR = 1.45, CI 95% 1.01–2.10, P = 0.047) to be significant independent prognosticators for DSS. Besides, there was an additive prognostic effect by the increasing number of highly expressed HIF hydroxylases. Provided none high expression HIF hydroxylases, the 5-year survival was 80% vs. 23% if all four were highly expressed (HR = 6.48, CI 95% 2.23–18.8, P = 0.001).

Conclusions

HIF hydroxylases are, in general, poor prognosticators for NSCLC survival. PHD1 and PHD2 are independent negative prognostic factors in NSCLC. Moreover, there is an additive poor prognostic impact by an increasing number of highly expressed HIF hydroxylases.     

LRRTM3 Interacts with APP and BACE1 and Has Variants Associating with Late-Onset Alzheimer’s Disease (LOAD)

Leucine rich repeat transmembrane protein 3 (LRRTM3) is member of a synaptic protein family. LRRTM3 is a nested gene within α-T catenin (CTNNA3) and resides at the linkage peak for late-onset Alzheimer’s disease (LOAD) risk and plasma amyloid β (Aβ) levels. In-vitro knock-down of LRRTM3 was previously shown to decrease secreted Aβ, although the mechanism of this is unclear. In SH-SY5Y cells overexpressing APP and transiently transfected with LRRTM3 alone or with BACE1, we showed that LRRTM3 co-localizes with both APP and BACE1 in early endosomes, where BACE1 processing of APP occurs. Additionally, LRRTM3 co-localizes with APP in primary neuronal cultures from Tg2576 mice transduced with LRRTM3-expressing adeno-associated virus. Moreover, LRRTM3 co-immunoprecipitates with both endogenous APP and overexpressed BACE1, in HEK293T cells transfected with LRRTM3. SH-SY5Y cells with knock-down of LRRTM3 had lower BACE1 and higher CTNNA3 mRNA levels, but no change in APP. Brain mRNA levels of LRRTM3 showed significant correlations with BACE1, CTNNA3 and APP in ∼400 humans, but not in LRRTM3 knock-out mice. Finally, we assessed 69 single nucleotide polymorphisms (SNPs) within and flanking LRRTM3 in 1,567 LOADs and 2,082 controls and identified 8 SNPs within a linkage disequilibrium block encompassing 5′UTR-Intron 1 of LRRTM3 that formed multilocus genotypes (MLG) with suggestive global association with LOAD risk (p = 0.06), and significant individual MLGs. These 8 SNPs were genotyped in an independent series (1,258 LOADs and 718 controls) and had significant global and individual MLG associations in the combined dataset (p = 0.02–0.05). Collectively, these results suggest that protein interactions between LRRTM3, APP and BACE1, as well as complex associations between mRNA levels of LRRTM3, CTNNA3, APP and BACE1 in humans might influence APP metabolism and ultimately risk of AD.