Genetic susceptibility to obsessive-compulsive hoarding: the contribution of neurotrophic tyrosine kinase receptor type 3 gene

Recent work suggests that neurotrophic factors may contribute to the genetic susceptibility to obsessive-compulsive disorder (OCD). Among other clinical dimensions, the presence of hoarding obsessions and compulsions has been shown to be correlated with a number of clinical and neuroimaging findings, as well as with a different pattern of genetic inheritance. We used a linkage disequilibrium (LD)-mapping approach to investigate whether neurotrophic tyrosine kinase receptor type 3 (NTRK3), the high-affinity receptor of neurotrophin 3 (NT-3), plays a role in increasing susceptibility to hoarding in OCD. We performed an association study of 52 tag single nucleotide polymorphisms (tagSNPs) covering the whole NTRK3 gene in a sample comprising 120 OCD patients and 342 controls. Single nucleotide polymorphism association and haplotype analysis were performed. Thirty-six of our patients (30%) exhibited significant hoarding obsessions and compulsions. A significant association of two SNPs in the 3' downstream region of NTRK3 gene and obsessive-compulsive hoarding was identified: rs1017412 [odds ratio (OR) = 2.16; P = 0.001] and rs7176429 (OR = 2.78; P = 0.0001), although only the latter remained significant after Bonferroni correction. Although the haplotype analysis did not show significant results, a more extended block of LD in the OCD hoarders with respect to the control group was observed, suggesting a lower haplotype diversity in these individuals. Our findings suggest that NTRK3 may contribute to the genetic susceptibility to hoarding in OCD and may constitute an interesting gene to focus on in studies of the genetic basis of obsessive-compulsive hoarding.     

Involvement of the carboxy-terminus region of the dihydropyridine receptor beta1a subunit in excitation-contraction coupling of skeletal muscle

Skeletal muscle knockout cells lacking the beta subunit of the dihydropyridine receptor (DHPR) are devoid of slow L-type Ca(2+) current, charge movements, and excitation-contraction coupling, despite having a normal Ca(2+) storage capacity and Ca(2+) spark activity. In this study we identified a specific region of the missing beta1a subunit critical for the recovery of excitation-contraction. Experiments were performed in beta1-null myotubes expressing deletion mutants of the skeletal muscle-specific beta1a, the cardiac/brain-specific beta2a, or beta2a/beta1a chimeras. Immunostaining was used to determine that all beta constructs were expressed in these cells. We examined the Ca(2+) conductance, charge movements, and Ca(2+) transients measured by confocal fluo-3 fluorescence of transfected myotubes under whole-cell voltage-clamp. All constructs recovered an L-type Ca(2+) current with a density, voltage-dependence, and kinetics of activation similar to that recovered by full-length beta1a. In addition, all constructs except beta2a mutants recovered charge movements with a density similar to full-length beta1a. Thus, all beta constructs became integrated into a skeletal-type DHPR and, except for beta2a mutants, all restored functional DHPRs to the cell surface at a high density. The maximum amplitude of the Ca(2+) transient was not affected by separate deletions of the N-terminus of beta1a or the central linker region of beta1a connecting two highly conserved domains. Also, replacement of the N-terminus half of beta1a with that of beta2a had no effect. However, deletion of 35 residues of beta1a at the C-terminus produced a fivefold reduction in the maximum amplitude of the Ca(2+) transients. A similar observation was made by deletion of the C-terminus of a chimera in which the C-terminus half was from beta1a. The identified domain at the C-terminus of beta1a may be responsible for colocalization of DHPRs and ryanodine receptors (RyRs), or may be required for the signal that opens the RyRs during excitation-contraction coupling. This new role of DHPR beta in excitation-contraction coupling represents a cell-specific function that could not be predicted on the basis of functional expression studies in heterologous cells.     

Deletion of Mbtps1 (Pcsk8, S1p,Ski-1) Gene in Osteocytes Stimulates Soleus Muscle Regeneration and Increased Size and Contractile Force with Age

Conditional deletion of Mbtps1 (cKO) protease in bone osteocytes leads to an age-related increase in mass (12%) and in contractile force (30%) in adult slow twitch soleus muscles (SOL) with no effect on fast twitch extensor digitorum longus muscles. Surprisingly, bone from 10–12-month-old cKO animals was indistinguishable from controls in size, density, and morphology except for a 25% increase in stiffness. cKO SOL exhibited increased expression of Pax7, Myog, Myod1, Notch, and Myh3 and 6-fold more centralized nuclei, characteristics of postnatal regenerating muscle, but only in type I myosin heavy chain-expressing cells. Increased expression of gene pathways mediating EGF receptor signaling, circadian exercise, striated muscle contraction, and lipid and carbohydrate oxidative metabolism were also observed in cKO SOL. This muscle phenotype was not observed in 3-month-old mice. Although Mbtps1 mRNA and protein expression was reduced in cKO bone osteocytes, no differences in Mbtps1 or cre recombinase expression were observed in cKO SOL, explaining this age-related phenotype. Understanding bone-muscle cross-talk may provide a fresh and novel approach to prevention and treatment of age-related muscle loss.     

Influence of a natural and a synthetic inhibitor of factor XIIIa on fibrin clot rheology

We investigated the origins of greater clot rigidity associated with FXIIIa-dependent cross-linking. Fibrin clots were examined in which cross-linking was controlled through the use of two inhibitors: a highly specific active-center-directed synthetic inhibitor of FXIIIa, 1,3-dimethyl-4,5-diphenyl-2[2(oxopropyl)thio]imidazolium trifluoromethylsulfonate, and a patient-derived immunoglobulin directed mainly against the thrombin-activated catalytic A subunits of thrombin-activated FXIII. Cross-linked fibrin chains were identified and quantified by one- and two-dimensional gel electrophoresis and immunostaining with antibodies specific for the alpha- and gamma-chains of fibrin. Gamma-dimers, gamma-multimers, alpha(n)-polymers, and alpha(p)gamma(q)-hybrids were detected. The synthetic inhibitor was highly effective in preventing the production of all cross-linked species. In contrast, the autoimmune antibody of the patient caused primarily an inhibition of alpha-chain cross-linking. Clot rigidities (storage moduli, G') were measured with a cone and plate rheometer and correlated with the distributions of the various cross-linked species found in the clots. Our findings indicate that the FXIIIa-induced dimeric cross-linking of gamma-chains by itself is not sufficient to stiffen the fibrin networks. Instead, the augmentation of clot rigidity was more strongly correlated with the formation of gamma-multimers, alpha(n)-polymers, and alpha(p)gamma(q)-hybrid cross-links. A mechanism is proposed to explain how these cross-linked species may enhance clot rigidity.     

Using hydrogel and clay to improve the water status of seedlings for dryland restoration

The decomposition of soil organic matter is mediated by extracellular enzymes. The aim of this work was to identify the factors determining the activity and size of the mobile fraction of extracellular enzymes (laccase, Mn-peroxidase, endocellulase, cellobiohydrolase, ??-glucosidase, endoxylanase, ??-xylosidase, ??-glucosidase, chitinase, arylsulfatase, phosphatase, phosphodiesterase, alanine and leucine aminopeptidase) using a set of soils covering a wide range of physico-chemical properties. Organic matter content had a major effect on enzyme activity both in forest and grassland soils, while the effects of pH and humic compounds content were only important in forest soils, and the molecular mass of humic compounds and Ca content were only important in grasslands. Specific enzyme activity was either comparable between the soil types or higher in grasslands. With the exception of Mn-peroxidase and ??-glucosidase, the specific activities of all enzymes in arable fields under tillage were similar to those in grasslands. Mobility differed among the enzymes and ranged from <1% for arylsulfatase and phosphodiesterase up to 20?C40% for ??-glucosidase and aminopeptidases, with pH being the most important variable. These results demonstrate that the factors regulating enzyme activity are likely to be different in forest soils and grasslands and that enzyme mobility is a characteristic feature of each individual enzyme.     

Assessment of Genetic Correlation between Bacterial Cold Water Disease Resistance and Spleen Index in a Domesticated Population of Rainbow Trout: Identification of QTL on Chromosome Omy19

Selective breeding of animals for increased disease resistance is an effective strategy to reduce mortality in aquaculture. However, implementation of selective breeding programs is limited by an incomplete understanding of host resistance traits. We previously reported results of a rainbow trout selection program that demonstrated increased survival following challenge with Flavobacterium psychrophilum, the causative agent of bacterial cold water disease (BCWD). Mechanistic study of disease resistance identified a positive phenotypic correlation between post-challenge survival and spleen somatic-index (SI). Herein, we investigated the hypothesis of a genetic correlation between the two traits influenced by colocalizing QTL. We evaluated the inheritance and calculated the genetic correlation in five year-classes of odd- and even-year breeding lines. A total of 322 pedigreed families (n = 25,369 fish) were measured for disease resistance, and 251 families (n = 5,645 fish) were evaluated for SI. Spleen index was moderately heritable in both even-year (h² = 0.56±0.18) and odd-year (h² = 0.60±0.15) lines. A significant genetic correlation between SI and BCWD resistance was observed in the even-year line (r_g = 0.45±0.20, P = 0.03) but not in the odd-year line (r_g = 0.16±0.12, P = 0.19). Complex segregation analyses of the even-year line provided evidence of genes with major effect on SI, and a genome scan of a single family, 2008132, detected three significant QTL on chromosomes Omy19, 16 and 5, in addition to ten suggestive QTL. A separate chromosome scan for disease resistance in family 2008132 identified a significant BCWD QTL on Omy19 that was associated with time to death and percent survival. In family 2008132, Omy19 microsatellite alleles that associated with higher disease resistance also associated with increased spleen size raising the hypothesis that closely linked QTL contribute to the correlation between these traits. To our knowledge, this is the first estimation of spleen size heritability and evidence for genetic linkage with specific disease resistance in a teleost fish.     

LAITOR - Literature Assistant for Identification of Terms co-Occurrences and Relationships

Background  

Biological knowledge is represented in scientific literature that often describes the function of genes/proteins (bioentities) in terms of their interactions (biointeractions). Such bioentities are often related to biological concepts of interest that are specific of a determined research field. Therefore, the study of the current literature about a selected topic deposited in public databases, facilitates the generation of novel hypotheses associating a set of bioentities to a common context.     

Comparison of Ca(2+) sparks produced independently by two ryanodine receptor isoforms (type 1 or type 3)

The molecular determinants of a Ca(2+) spark, those events that determine the sudden opening and closing of a small number of ryanodine receptor (RyR) channels limiting Ca(2+) release to a few milliseconds, are unknown. As a first step we investigated which of two RyR isoforms present in mammalian embryonic skeletal muscle, RyR type 1(RyR-1) or RyR type 3 (RyR-3) has the ability to generate Ca(2+) sparks. Their separate contributions were investigated in intercostal muscle cells of RyR-1 null and RyR-3 null mouse embryos. A comparison of Ca(2+) spark parameters of RyR-1 null versus RyR-3 null cells measured at rest with fluo-3 showed that neither the peak fluorescence intensity (DeltaF/F(o) = 1.25 +/- 0.7 vs. 1.55 +/- 0.6), spatial width at half-max intensity (FWHM = 2.7 +/- 1.2 vs. 2.6 +/- 0.6 microm), nor the duration at half-max intensity (FTHM = 45 +/- 49 vs. 43 +/- 25 ms) was significantly different. Sensitivity to caffeine (0.1 mM) was remarkably different, with sparks in RyR-1 null myotubes becoming brighter and longer in duration, whereas those in RyR-3 null cells remained unchanged. Controls performed in double RyR-1/RyR-3 null cells obtained by mice breeding showed that sparks were not observed in the absence of both isoforms in >150 cells imaged. In conclusion, 1) RyR-1 and RyR-3 appear to be the only intracellular Ca(2+) channels that participate in Ca(2+) spark activity in embryonic skeletal muscle; 2) except in their responsiveness to caffeine, both isoforms have the ability to produce Ca(2+) sparks with nearly identical properties, so it is rather unlikely that a single RyR isoform, when others are also present, would be responsible for Ca(2+) sparks; and 3) because RyR-1 null cells are excitation-contraction (EC) uncoupled and RyR-3 null cells exhibit a normal phenotype, Ca(2+) sparks result from the inherent activity of small clusters of RyRs regardless of the participation of these RyRs in EC coupling.     

A fluorescamine-based sensitive method for the assay of proteinases, capable of detecting the initial cleavage steps of a protein.

The properties of the reaction of fluorescamine with proteins are the basis for the development of a sensitive, general and simple method for the assay of proteolytic activities. More importantly, the assay measures the initial step(s) of proteolytic attack, making it specially suitable for the examination of the controlling factors that regulate proteolytic degradation and/or the detection of 'specific' proteinases. The method allows the simple determination of the general parameters of enzyme action, V and Km, using proteins, i.e. the physiological substrates of the proteinases. The more appropriate proteins to be used as substrates are the N-amino-terminally blocked ones. Many proteins fulfill this requirement. If the particular protein whose degradation has to be studied lacks this modification, three different approaches can be used to study its degradation: (a) the accumulation of N-amino termini in excess over that of the intact substrate; (b) a gel filtration/continuous method and (c) the chemical blockage of its amino groups. The particular advantages of each of these approaches are discussed.