Four rhoptry proteins (ROP) of Toxoplasma gondii previously identified with mAb have been affinity purified and analyzed by MS; the data obtained allowed the genomic sequences to be assigned to these proteins. As previously suggested for some of them by antibody crossreactivity, these proteins were shown to belong to a family, the prototype of which being ROP2. We describe here the proteins ROP2, 4, 5, and 7. These four proteins correspond to the most abundant products of a gene family that comprises several members which we have identified in genomic and EST libraries. Eight additional sequences were found and we have cloned four of them. All members of the ROP2 family contain a protein-kinase-like domain, but only some of them possess a bona fide kinase catalytic site. Molecular modeling of the kinase domain demonstrates the conservation of residues critical for the stabilization of the protein-kinase fold, especially within a hydrophobic segment described so far as transmembrane and which appears as an helix buried inside the protein. The concomitant synthesis of these ROPs by T. gondii tachyzoites suggests a specific role for each of these proteins, especially in the early interaction with the host cell upon invasion.

The 5-hydroxytryptamine type 2A (5-HT 2A ) receptor and the 5-HT 2C receptor are closely related members of the G-protein-coupled receptors activated by serotonin that share very similar pharmacological profiles and cellular signaling pathways. These receptors express a canonical class I PDZ ligand (SXV) at their C-terminal extremity. Here, we have identified proteins that interact with the PDZ ligand of the 5-HT 2A and 5-HT 2C receptors by a proteomic approach associating affinity chromatography using immobilized synthetic peptides encompassing the PDZ ligand and mass spectrometry. We report that both receptor C termini interact with specific sets of PDZ proteins in vitro. ) is a major neurotransmitter that is involved in numerous functions of the mammalian central nervous system. These functions are mediated by a large number of receptors. Except for the 5-HT 3 receptor, which is a ligand-gated channel, all 5-HT receptors belong to the Gprotein-coupled receptor (GPCR) superfamily. Among the GPCRs activated by 5-HT, the 5-HT 2 receptor family, namely the 5-HT 2A , the 5-HT 2B , and the 5-HT 2C receptors, continues to raise particular interest. Indeed, they are involved in multiple physiological functions such as the control of endocrine secretion, motor behavior, mood, pain, sleep, thermoregulation, and appetite (1). Moreover, a large number of psychoactive drugs, including non-classical antipsychotic drugs, hallucinogens, anxiolytics, and anti-depressants, mediate their action at least in part through activation of 5-HT 2 receptors (1-4).Among the 5-HT 2 receptor family, the 5-HT 2A and the 5-HT 2C receptor are widely distributed in the central nervous system, whereas the 5-HT 2B receptor is sparse. The 5-HT 2A and the 5-HT 2C receptors share the highest degree of sequence homology (about 50% overall sequence identity). Thus, it is not surprising that these receptors have very similar pharmacological profiles and that only a few selective ligands are available. Initial studies of 5-HT 2A and 5-HT 2C receptor signaling showed that both receptors activate phosphatidyl inositol hydrolysis. However, some differences in signal transduction characteristics of these receptors have been reported (5, 6). In NIH3T3 cells expressing the 5-HT 2C receptor, agonist-independent activity was much more elevated than that measured in cells expressing the same density of 5-HT 2A receptors (7). This indicates that the 5-HT 2A receptor has lower intrinsic ability to adopt an active conformation than does the 5-HT 2C receptor. Different mechanisms of desensitization for the 5-HT 2A and 5-HT 2C receptor systems have also been described. In Chinese hamster ovary cells, agonist-induced desensitization of the 5-HT 2A receptor-mediated phospholipase C activation is inhibited by inhibitors of protein kinase C and Ca 2ϩ -calmodulin-dependent protein kinase II (8). In contrast, the 5-HT 2C receptormediated response is insensitive to these inhibitors. Moreover, the desensitization of the 5-HT 2C receptor system but not that of the 5-HT 2A r...

CSF CHI3L1 and CHI3L2 and serum CHI3L1 might help to define MS disease stage and have a prognostic value in CIS.

The parasitic Nematomorph hairworm, Spinochordodes tellinii (Camerano) develops inside the terrestrial grasshopper, Meconema thalassinum (De Geer) (Orthoptera: Tettigoniidae), changing the insect's responses to water. The resulting aberrant behaviour makes infected insects more likely to jump into an aquatic environment where the adult parasite reproduces. We used proteomics tools (i.e. two-dimensional gel electrophoresis (2-DE), computer assisted comparative analysis of host and parasite protein spots and MALDI-TOF mass spectrometry) to identify these proteins and to explore the mechanisms underlying this subtle behavioural modification. We characterized simultaneously the host (brain) and the parasite proteomes at three stages of the manipulative process, i.e. before, during and after manipulation. For the host, there was a differential proteomic expression in relation to different effects such as the circadian cycle, the parasitic status, the manipulative period itself, and worm emergence. For the parasite, a differential proteomics expression allowed characterization of the parasitic and the free-living stages, the manipulative period and the emergence of the worm from the host. The findings suggest that the adult worm alters the normal functions of the grasshopper's central nervous system (CNS) by producing certain 'effective' molecules. In addition, in the brain of manipulated insects, there was found to be a differential expression of proteins specifically linked to neurotransmitter activities. The evidence obtained also suggested that the parasite produces molecules from the family Wnt acting directly on the development of the CNS. These proteins show important similarities with those known in other insects, suggesting a case of molecular mimicry. Finally, we found many proteins in the host's CNS as well as in the parasite for which the function(s) are still unknown in the published literature (www) protein databases. These results support the hypothesis that host behavioural changes are mediated by a mix of direct and indirect chemical manipulation.

Despite increasing evidence of host phenotypic manipulation by parasites, the underlying mechanisms causing infected hosts to act in ways that benefit the parasite remain enigmatic in most cases. Here, we used proteomics tools to identify the biochemical alterations that occur in the head of the cricket Nemobius sylvestris when it is driven to water by the hairworm Paragordius tricuspidatus. We characterized host and parasite proteomes during the expression of the water-seeking behaviour. We found that the parasite produces molecules from the Wnt family that may act directly on the development of the central nervous system (CNS). In the head of manipulated cricket, we found differential expression of proteins specifically linked to neurogenesis, circadian rhythm and neurotransmitter activities. We also detected proteins for which the function(s) are still unknown. This proteomics study on the biochemical pathways altered by hairworms has also allowed us to tackle questions of physiological and molecular convergence in the mechanism(s) causing the alteration of orthoptera behaviour. The two hairworm species produce effective molecules acting directly on the CNS of their orthoptera hosts.

SRY, a Y chromosome-encoded DNA-binding protein, is required for testis organogenesis in mammals. Expression of the SRY gene in the genital ridge is followed by diverse early cell events leading to Sertoli cell determination/differentiation and subsequent sex cord formation. Little is known about SRY regulation and its mode of action during testis development, and direct gene targets for SRY are still lacking. In this study, we demonstrate that interaction of the human SRY with histone acetyltransferase p300 induces the acetylation of SRY both in vitro and in vivo at a single conserved lysine residue. We show that acetylation participates in the nuclear localisation of SRY by increasing SRY interaction with importin b, while specific deacetylation by HDAC3 induces a cytoplasmic delocalisation of SRY. Finally, by analysing p300 and HDAC3 expression profiles during both human or mouse gonadal development, we suggest that acetylation and deacetylation of SRY may be important mechanisms for regulating SRY activity during mammalian sex determination.

Astrocytes, the most abundant cell type in the central nervous system, are intimately associated with synapses. They play a pivotal role in neuronal survival and the brain inflammatory response. Some astrocytic functions are mediated by the secretion of polypeptides. Using a proteomic approach, we have identified more than 30 proteins released by cultured astrocytes. These include proteases and protease inhibitors, carrier proteins, and antioxidant proteins. Exposing astrocytes to brefeldin A, which selectively blocks secretory vesicle assembly, suppressed the release of some of these proteins. This indicates that astrocytes secrete these proteins by a classic vesicular mechanism and others by an alternative pathway. Astrocytes isolated from different brain regions secreted a similar pattern of proteins. However, the secretion of some of them, including metalloproteinase inhibitors and apolipoprotein E, was region-specific. In addition, pro-inflammatory treatments modified the profile of astrocytic protein secretion. Finally, more than two thirds of the proteins identified in the astrocyte-conditioned medium were detectable in the mouse cerebrospinal fluid, suggesting that astrocytes contribute to the cerebrospinal fluid protein content. In conclusion, this study provides the first unbiased characterization of the major proteins released by astrocytes, which may play a crucial role in the modulation of neuronal survival and function.Glial cells represent the largest cell population in the central nervous system (CNS).1 They are divided into three categories:astrocytes, the most abundant glial cell type, oligodendrocytes, the central equivalent of Schwann cells, and microglial cells, which share features with immune cells. For decades, astrocytes were essentially considered to be passive elements providing a structural support for neurons and contributing to the blood-brain barrier by wrapping processes around CNS microvessels. Several physiological properties related to CNS homeostasis (clearance and metabolism of neurotransmitters, regulation of extracellular pH, and K ϩ level) have also been attributed to astrocytes, which thereby contribute to the maintenance of an ideal environment for neuronal cell function (1).Many recent studies have established that astrocytes, which are intimately associated with synapses, are active integrators and regulators of neuronal activity and synaptic transmission (2-6). These astrocytic functions are mediated, at least in part, by the release of various substances, including amino acids and polypeptides. Indeed, glutamate released from synaptic terminals not only binds to glutamate receptors on the post-synaptic neurons but also activates ␣-amino-3-hydroxy-5-methylisoxazole-4-propionic acid receptors on the surrounding astrocytes. This activation induces a rapid increase in intracellular Ca 2ϩ and a Ca 2ϩ -dependent release of glutamate from astrocytes that in turn activates post-synaptic glutamate receptors on neighboring neurons, thereby enhancing excitatory synaptic transmi...

Insulin-like growth factor-1 (IGF-1) and pituitary adenylyl cyclase activating polypeptide (PACAP) are both potent neurotrophic and antiapoptotic factors, which exert their effects via phosphorylation cascades initiated by tyrosine kinase and G-protein-coupled receptors, respectively. Here, we have adapted a recently described phosphoproteomic approach to neuronal cultures to characterize the phosphoproteomes generated by these neurotrophic factors. Unexpectedly, IGF-1 and PACAP increased the phosphorylation state of a common set of proteins in neurons. Using PACAP type 1 receptor (PAC1R) null mice, we showed that IGF-1 transactivated PAC1Rs constitutively associated with IGF-1 receptors. This effect was mediated by Src family kinases, which induced PAC1R phosphorylation on tyrosine residues. PAC1R transactivation was responsible for a large fraction of the IGF-1-associated phosphoproteome and played a critical role in the antiapoptotic activity of IGF-1. Hence, in contrast to the general opinion that the trophic activity of IGF-1 is solely mediated by tyrosine kinase receptor-associated signalling, we show that it involves a more complex signalling network dependent on the PAC1 Gs-protein-coupled receptor in neurons.