Gene genealogies reveal differentiation at sex pheromone olfactory receptor loci in pheromone strains of the European corn borer, Ostrinia nubilalis

Males of the E and Z strains of the European corn borer Ostrinia nubilalis (Lepidoptera: Crambidae) are attracted to different blends of the same pheromone components. The difference in male behavioral response is controlled by the sex-linked locus Resp. The two types of males have identical neuroanatomy but their physiological specificity is reversed, suggesting that variation at the periphery results in behavioral change. Differences in the olfactory receptors (ORs) could explain the strain-specific antennal response and blend preference. Gene genealogies can provide insights into the processes involved in speciation and allow delineation of genome regions that contribute to reproductive barriers. We used intronic DNA sequences from five OR-encoding genes to investigate whether they exhibit fixed differences between strains and therefore might contribute to reproductive isolation. Although two genealogies revealed shared polymorphism, molecular polymorphism at three genes revealed nearly fixed differences between strains. These three OR genes map to the sex chromosome, but our data indicate that the distance between Resp and the ORs is >20 cM, making it unlikely that variation in pheromone-sensitive OR genes is directly responsible for the difference in behavioral response. However, differences in male antennal response may have their origin in the selection of strain-specific alleles.     

Interactions of β-lactoglobulin with serotonin and arachidonyl serotonin

β‐Lactoglobulin (β‐LG) is a lipocalin, which is the major whey protein of cow's milk and the milk of other mammals. However, it is absent from human milk. The biological function of β‐LG is not clear, but its potential role in carrying fatty acids through the digestive tract has been suggested. β‐LG has been found in complexes with lipids such as butyric and oleic acids and has a high affinity for a wide variety of compounds. Serotonin (5‐hydroxytryptamine, 5‐HT), an important compound found in animals and plants, has various functions, including the regulation of mood, appetite, sleep, muscle contraction, and some cognitive functions such as memory and learning. In this study, the interaction of serotonin and one of its derivatives, arachidonyl serotonin (AA‐5HT), with β‐LG was investigated using circular dichroism (CD) and fluorescence intensity measurements. These two ligands interact with β‐LG forming equimolar complexes. The binding constant for the serotonin/β‐LG interaction is between 10⁵ and 10⁶ M⁻¹, whereas for the AA‐5HT/β‐LG complex it is between 10⁴ and 10⁵ M⁻¹ as determined by measurements of either protein or ligand fluorescence. The observed binding affinities were higher in hydroethanolic media (25% EtOH). The interactions between serotonin/β‐LG and AA‐5HT/β‐LG may compete with self‐association (micellization) of both the ligand and the protein. According to far‐ and near‐UV CD results, these ligands have no apparent influence on β‐LG secondary structure, however they partially destabilize its tertiary structure. Their binding by β‐LG may be one of the peripheral mechanisms of the regulation of the content of serotonin and its derivatives in the bowel of milk‐fed animals. © 2011 Wiley Periodicals, Inc. Biopolymers 95: 871–880, 2011.     

Insight into the mode of action of the LRRK2 Y1699C pathogenic mutant

Mutations in the leucine-rich repeat kinase 2 (LRRK2) gene are the most prevalent known cause of autosomal dominant Parkinson's disease. The LRRK2 gene encodes a Roco protein featuring a Ras of complex proteins (ROC) GTPase and a kinase domain linked by the C-terminal of ROC (COR) domain. Here, we explored the effects of the Y1699C pathogenic LRRK2 mutation in the COR domain on GTPase activity and interactions within the catalytic core of LRRK2. We observed a decrease in GTPase activity for LRRK2 Y1699C comparable to the decrease observed for the R1441C pathogenic mutant and the T1348N dysfunctional mutant. To study the underlying mechanism, we explored the dimerization in the catalytic core of LRRK2. ROC-COR dimerization was significantly weakened by the Y1699C or R1441C/G mutation. Using a competition assay, we demonstrated that the intra-molecular ROC : COR interaction is favoured over ROC : ROC dimerization. Interestingly, the intra-molecular ROC : COR interaction was strengthened by the Y1699C mutation. This is supported by a 3D homology model of the ROC-COR tandem of LRRK2, showing that Y1699 is positioned at the intra-molecular ROC : COR interface. In conclusion, our data provides mechanistic insight into the mode of action of the Y1699C LRRK2 mutant: the Y1699C substitution, situated at the intra-molecular ROC : COR interface, strengthens the intra-molecular ROC : COR interaction, thereby locally weakening the dimerization of LRRK2 at the ROC-COR tandem domain resulting in decreased GTPase activity.     

Effect of spinal level and loading conditions on the production of vertebral burst fractures in a porcine model

Vertebral burst fractures are commonly studied with experimental animal models. There is however a lack of consensus as to what parameters are important to create an unstable burst fracture with a significant canal encroachment on such model. This study aims to assess the effect of the loading rate, flexion angle, spinal level, and their interactions on the production of a vertebral thoracolumbar burst fracture on a porcine model. Sixteen functional spinal units composed of three vertebrae were harvested from mature Yucatan minipigs. Two loading rates (0.01 and 500 mm/s), two flexion angles (0° and 15°), and two spinal levels (T11-T13 and T14-L2) were studied, following a full factorial experimental plan with one repetition. Compression was applied to each functional unit to create a vertebral fracture. The load-to-failure, loss of compressive stiffness, final canal encroachment, and fracture type were used as criteria to evaluate the resulting fracture. All specimens compressed without flexion resulted in burst fractures. Half of the specimens compressed with the 15° flexion angle resulted in compression fractures. Specimens positioned without flexion lost more of their compressive stiffness and had more significant canal encroachment. Fractured units compressed with a higher loading rate resulted in a greater loss of compressive stiffness. The spinal level had no significant effect on the resulting fractures. The main parameters which affect the resulting fracture are the loading rate and the flexion angle. A higher loading rate and the absence of flexion favors the production of burst fractures with a greater canal encroachment.     

Inter-ethnic variability of three functional polymorphisms affecting the IMPDH2 gene

Human type II inosine monophosphate dehydrogenase (IMPDH2) is a key enzyme in the purine nucleotide biosynthetic pathway and constitutes a pivotal biological target for immunosuppressant and antiviral drugs. Several Single Nucleotide Polymorphisms (SNP) affecting the IMPDH2 gene sequence have been reported with potential functional relevance and could impact drugs response. We aimed to determine the frequency of three of these polymorphisms, namely g.3375C>T (Leu(263)Phe), c.-95T>G and IVS7+10T>C, in Caucasians, Tunisians, Peruvians and Black Africans (Gabonese and Senegalese). The g.3375C>T and c.-95T>G polymorphisms are rare with a Minor Allele Frequency ≤1.0% in our populations, whereas the third variant, IVS7+10T>C, is more frequent and displays large interethnic variations, with an allelic frequency ranging from 14.6% in the French Caucasian population studied to less than 2% in Black African and Peruvian populations. This ethnic-related data might contribute to a better understanding of the variability in clinical outcome and/or dose adjustments of drugs that are IMPDH inhibitors such as mycophenolic acid.     

Amino-benzosuberone: a novel warhead for selective inhibition of human aminopeptidase-N/CD13

This paper describes the design and synthesis of compounds belonging to a novel class of highly selective mammalian CD13 inhibitors. Racemic homologues of 3-amino-2-tetralone 1 were synthesised and evaluated for their ability to selectively inhibit the membrane-bound, zinc-dependent aminopeptidase-N/CD13 (EC 3.4.11.2). Some of these novel non-peptidic compounds are potent, competitive inhibitors of the mammalian enzyme, with K(i) values in the low micromolar range in spite of their minimal size (MW <200 Da). Moreover, they show an interesting selectivity profile against representative members of the aminopeptidase family, that is leucine aminopeptidase (EC 3.4.11.1), Aeromonas proteolytica aminopeptidase (EC 3.4.11.10) and the aminopeptidase activity of leukotriene A4 hydrolase (EC 3.3.2.6). The amino-benzosuberone derivative 4 is the most promising compound in terms of potency, stability and selectivity. A hypothetical binding mode of 4 to the catalytic zinc and several conserved active site residues is proposed, based on the observed structure-activity relationships, structural insights from aminopeptidase-N homologues of known three-dimensional structure.     

Discovery of novel and orally active FXR agonists for the potential treatment of dyslipidemia & diabetes

Herein we describe the synthesis and structure activity relationship of a new class of FXR agonists identified from a high-throughput screening campaign. Further optimization of the original hits led to molecules that were highly active in an LDL-receptor KO model for dyslipidemia. The most promising candidate is discussed in more detail.     

Role of sulfatide in vaccinia virus infection

Background information. Vaccinia virus (VACV) was used as a surrogate of variola virus (genus Orthopoxvirus), the causative agent of smallpox, to study orthopoxvirus infection. VACV infects cells via attachment and fusion of the viral membrane with the host cell membrane. Glycosphingolipids, expressed in multiple organs, are major components of lipid rafts and have been associated with the infectious route of several pathogens. Results. We demonstrate that the VACV‐WR (VACV Western‐Reserve strain) displays no binding to Cer (ceramide) or to Gal‐Cer (galactosylceramide), but binds to a natural sulfated derivative of these molecules: the Sulf (sulfatide) 3′ sulfogalactosylceramide. The interaction between Sulf and VACV‐WR resulted in a time‐dependent inhibition of virus infection. Virus cell attachment was the crucial step inhibited by Sulf. Electron microscopy showed that SUVs (small unilamellar vesicles) enriched in Sulf bound to VACV particles. Both the A27 and L5 viral membrane proteins were shown to interact with Sulf, indicating that they could be the major viral ligands for Sulf. Soluble Sulf was successful in preventing mortality, but not morbidity, in a lethal mouse model infection with VACV‐WR. Conclusions. Together the results suggest that Sulf could play a role as an alternate receptor for VACV‐WR and probably other Orthopoxviruses.     

Efficient in vitro myogenic reprogramming of human primary mesenchymal stem cells and endothelial cells by Myf5

Background information. The identification of a source of stem cells able to regenerate skeletal muscle was the goal of numerous studies with the aim to develop new therapeutic approaches for genetic muscle diseases or muscle injuries. A series of studies have demonstrated that stem cells derived from various tissues may have a role in the regeneration of damaged muscles, but this contribution is always very weak. Thus we established a project aiming to reprogramme non‐muscle cells into the skeletal striated differentiation pathway. Results. We transduced several human primary adult stem or progenitor cells using a recombinant lentivirus containing the coding sequence of the Myf5 gene considered as a master gene for the determination of skeletal striated muscle. These original results are the first demonstration of a myogenic conversion of human mesenchymal and endothelial cells by Myf5. Conclusions. The procedure described in the present paper could be used to develop new research protocols with the prospect of using these cells as therapeutic agents.