Monosaccharides modulate HCV E2 protein-derived peptide biological properties

A hepatitis C virus E(2) protein-derived sequence was selected for studying the effect of N-glycosylation on the peptide chain's conformational structure. The results suggested that the (534)TDVF(537) motif contained in peptide 33402 ((529)WGENDTDVFVLNNTRY(544)) had a type III beta-turn, relevant in antigen recognition of polyclonal antibodies, binding to human cells, and binding to HLA DRB1 *0401 molecules. N-Glycopeptides derived from this sequence contained monosaccharides in Asn(532). N-Glycopeptides presented differences in peptide chain structure compared to non-glycosylated peptides. Peptide 33402 specifically bound to human cells, specificity becoming lost when it was N-glycosylated. N-Glycosylation decreased antigen recognition of mouse polyclonal sera against this sequence. N-Glycopeptide binding to HLA DRB1 *0401 molecules was similar to that presented by non-glycosylated peptide, indicating that N-glycosylation did not affect binding to HLA DRB1 *0401 molecules. N-Glycosylation induced changes at structural and functional level which could be relevant for modulating human cell binding properties and antibody recognition.     

M domains couple the ClpB threading motor with the DnaK chaperone activity

The AAA(+) chaperone ClpB mediates the reactivation of aggregated proteins in cooperation with the DnaK chaperone system. ClpB consists of two AAA domains that drive the ATP-dependent threading of substrates through a central translocation channel. Its unique middle (M) domain forms a coiled-coil structure that laterally protrudes from the ClpB ring and is essential for aggregate solubilization. Here, we demonstrate that the conserved helix 3 of the M domain is specifically required for the DnaK-dependent shuffling of aggregated proteins, but not of soluble denatured substrates, to the pore entrance of the ClpB translocation channel. Helix 3 exhibits nucleotide-driven conformational changes possibly involving a transition between folded and unfolded states. This molecular switch controls the ClpB ATPase cycle by contacting the first ATPase domain and establishes the M domain as a regulatory device that acts in the disaggregation process by coupling the threading motor of ClpB with the DnaK chaperone activity.     

Correlation between the hydration of acyl chains and phosphate groups in lipid bilayers: Effect of phase state,head group,chain length,double bonds and carbonyl groups

This paper demonstrates by means of FTIR/ATR analysis that water molecules intercalate at different extents in the acyl chain region of lipid membranes in correlation with the hydration of the phosphate groups.This correlation is sensible to the chain length, the presence of double bonds and the phase state of the lipid membrane.The presence of carbonyl groups CO modifies the profile of hydration of the two regions as observed from the comparison of DMPC and 14:0 Diether PC.The different water populations in lipid interphases would give arrangements with different free energy states that could drive the interaction of biological effectors with membranes.     

Lysophosphatidic acid induces the crosstalk between the endovascular human trophoblast and endothelial cells in vitro

Spiral artery remodeling at the maternal–fetal interface is crucial for successful pregnancy and requires the interaction between the first trimester trophoblast and the endothelial cells of the maternal vessels. However, the precise mechanism of this dialog has yet to be determined. The current study investigated whether lysophosphatidic acid (LPA) modulates trophoblast–endothelial crosstalk in vitro. HTR-8/SVneo trophoblast cell line (H8) was seeded on top of Geltrex, incubated with LPA or LPA + NS-398 (selective cyclooxygenase-2 inhibitor), LPA + 1400W (selective inducible nitric oxide synthase inhibitor) or LPA + IL-6 neutralizing antibody and assayed for tube formation to model the acquisition of trophoblast endovascular phenotype. The supernatants were collected and used as conditioned media (CM). To test trophoblast–endothelial crosstalk, the endothelial cell line EA.hy926 was incubated with trophoblast CM. The CM from LPA-induced tubulogenesis stimulated endothelial cells migration and did not modify the apoptosis. Soluble factors derived from cyclooxygenase-2 and IL-6 pathways were involved in H8–EA.hy926 interaction under the LPA effect. Moreover, LPA increased the levels of IL-6 mRNA by cyclooxygenase-2 pathway in H8 cells. Collectively, LPA promotes trophoblast–endothelial crosstalk in vitro and induces the release of trophoblast soluble factors that stimulate endothelial cells migration without changes in apoptosis. The evidence presented here provides new insights about an active role of LPA as a lipid mediator regulating vascular remodeling at the maternal–fetal interface.     

Reproductive biology of the 38 extant felid species: a review

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Is the vertebral canal prepared to host the aged spinal cord? A morphometric assessment

Although the interaction between the growing spinal cord and the vertebrae has been widely demonstrated for mammal’s prenatal and early postnatal life, there is no extensive knowledge about this interaction during late postnatal stages. It has been shown that spinal cord injuries are causally related to significant degenerative changes in bone properties. Nevertheless, information about a possible influence of the spinal cord on bone remodelling in adult healthy animals is missing. The aim of this research work was to assess possible morphological changes of the cervical vertebral canal of juvenile and aged rats during the ontogenetic period of adulthood that would justify the suggested influence. Since the spinal cord of rats increases its size with ageing, we analysed whether morphometric changes are occurring in the vertebral canal that would indicate bone remodelling in response to said growth. To this end, we used three complementary morphometric methods to describe the canal of the cervical and the first thoracic vertebrae. Geometric morphometric analyses evidence scarce variation in size and shape between juvenile and aged rats suggesting that, in general terms, the canal morphology of cervical vertebrae is already prepared in early adulthood to host the growing spinal cord. C3 was the only vertebra that showed consistent variation for the variables of canal thickness, perimeter, height and area. This regional variation may be linked to the patterns described for the changing spinal cord.     

Estrogens Induce Expression of Membrane-Associated Estrogen Receptor α Isoforms in Lactotropes

Estrogens are key to anterior pituitary function, stimulating hormone release and controlling cell fate to achieve pituitary dynamic adaptation to changing physiological conditions. In addition to their classical mechanism of action through intracellular estrogen receptors (ERs), estrogens exert rapid actions via cell membrane-localized ERs (mERs). We previously showed that E2 exerts a rapid pro-apoptotic action in anterior pituitary cells, especially in lactotropes and somatotropes, through activation of mERs. In the present study, we examined the involvement of mERα in the rapid pro-apoptotic action of estradiol by TUNEL in primary cultures of anterior pituitary cells from ovariectomized rats using a cell-impermeable E2 conjugate (E2-BSA) and an ERα selective antagonist (MPP dihydrochloride). We studied mERα expression during the estrous cycle and its regulation by gonadal steroids in vivo by flow cytometry. We identified ERα variants in the plasma membrane of anterior pituitary cells during the estrous cycle and studied E2 regulation of these mERα variants in vitro by surface biotinylation and Western Blot. E2-BSA-induced apoptosis was abrogated by MPP in total anterior pituitary cells and lactotropes. In cycling rats, we detected a higher number of lactotropes and a lower number of somatotropes expressing mERα at proestrus than at diestrus. Acute E2 treatment increased the percentage of mERα-expressing lactotropes whereas it decreased the percentage of mERα-expressing somatotropes. We detected three mERα isoforms of 66, 39 and 22 kDa. Expression of mERα66 and mERα39 was higher at proestrus than at diestrus, and short-term E2 incubation increased expression of these two mERα variants. Our results indicate that the rapid apoptotic action exerted by E2 in lactotropes depends on mERα, probably full-length ERα and/or a 39 kDa ERα variant. Expression and activation of mERα variants in lactotropes could be one of the mechanisms through which E2 participates in anterior pituitary cell renewal during the estrous cycle.     

Interaction between Lysophosphatidic Acid,Prostaglandins and the Endocannabinoid System during the Window of Implantation in the Rat Uterus

Bioactive lipid molecules as lysophosphatidic acid (LPA), prostaglandins (PG) and endocannabinoids are important mediators of embryo implantation. Based on previous published data we became interested in studying the interaction between these three groups of lipid derivatives in the rat uterus during the window of implantation. Thus, we adopted a pharmacological approach in vitro using LPA, DGPP (a selective antagonist of LPA3, an LPA receptor), endocannabinoids’ receptor selective antagonists (AM251 and AM630) and non selective (indomethacin) and selective (NS-398) inhibitors of cyclooxygenase-1 and 2 enzymes. Cyclooxygenase isoforms participate in prostaglandins’ synthesis. The incubation of the uterus from rats pregnant on day 5 of gestation (implantation window) with LPA augmented the activity and the expression of fatty acid amide hydrolase, the main enzyme involved in the degradation of endocannabinoids in the rodent uteri, suggesting that LPA decreased endocannabinoids’ levels during embryo implantation. It has been reported that high endocannabinoids are deleterious for implantation. Also, LPA increased PGE2 production and cyclooxygenase-2 expression. The incubation of LPA with indomethacin or NS-398 reversed the increment in PGE2 production, suggesting that cyclooxygenase-2 was the isoform involved in LPA effect. PGs are important mediators of decidualization and vascularization at the implantation sites. All these effects were mediated by LPA3, as the incubation with DGPP completely reversed LPA stimulatory actions. Besides, we also observed that endocannabinoids mediated the stimulatory effect of LPA on cyclooxygenase-2 derived PGE2 production, as the incubation of LPA with AM251 or AM630 completely reversed LPA effect. Also, LPA augmented via LPA3 decidualization and vascularization markers. Overall, the results presented here demonstrate the participation of LPA3 in the process of implantation through the interaction with other groups of lipid molecules, prostaglandins and endocannabinoids, which prepare the uterine milieu for embryo invasion during the window of implantation.