The signaling pathways of tyrosine kinase Trk receptors and their downstream biological effects are well known, but the parameters controlling the interactions between the receptors and their natural ligands still remain to be defined. Recent published reports from our laboratory indicate that nerve growth factor (NGF)-induced TrkA receptor activation is dependent on a membrane cellular sialidase. This sialidase activity specifically targets and hydrolyzes sialyl α-2, 3-linked β-galactosyl residues resulting in the desialylation and activation of the receptor. These findings support a novel hypothesis that places mammalian sialidase(s) in a cycle of activation of these receptors by their natural ligand. Taken together, they also predict a prerequisite desialylation of Trk receptors caused by a sialidase on the cell surface enabling the removal of a steric hindrance to receptor dimerization. Until now, the sialidase associated with neurotrophin-treated live Trk-expressing cells has not been identified. The molecular mechanism(s) of sialidase activation by neurotrophin factors binding to their receptors also remains unknown. In this thesis, the novel role of Neu1 sialidase in the activation of ligand-induced TrkA and TrkB receptors has been identified. It has been reported for the first time that Neu1 is already in complex with naïve and ligand-induced Trk receptors. In addition, a membrane sialidase mechanism initiated by NGF binding to TrkA has been indentified. It suggests a potentiation of GPCR-signaling via membrane Gαi subunit proteins and matrix metalloproteinase-9 (MMP-9) activation to induce Neu1 sialidase activation in live TrkA- and TrkB-expressing cells and primary neurons. These results establish a unique mode of regulation of Trk receptors by their natural ligand and define a new function for Neu1 sialidase. Preliminary data indicate that members of the family of tyrosine kinase receptors like epidermal growth factor receptor (EGFR) and insulin receptor are also under the same regulatory control of Neu1 sialidase. Recent reports from the laboratory have indicated that ligand-induced activation of the highly glycosylated Toll-like receptors, TLR-2,-3 and -4 is also dependent on Neu1 sialidase on the cell surface. Taken all together, the findings in this thesis uncover a Neu1 and MMP-9 cross-talk on the cell surface which is critically essential for neurotrophin-induced Trk tyrosine kinase receptor activation and neuron function. / Thesis (Ph.D, Microbiology & Immunology) -- Queen's University, 2010-04-26 11:44:51.418

Los factores y receptores neurotróficos son esenciales para el desarrollo y mantenimiento del sistema nervioso vertebrado y contribuyen de manera decisiva en funciones neuronales complejas tales como el aprendizaje, la memoria y el comportamiento social complejo. Dichos genes han sido estudiados en el anfioxo, un invertebrado marino que, por su plano corporal, desarrollo embrionario y genoma prototípico respecto a los vertebrados, es actualmente considerado el pariente vivo más cercano al que fue el ancestro de los vertebrados. Este estudio describe la caracterización a nivel molecular y funcional del primer receptor Trk jamás aislado en un invertebrado, rebatiendo la idea de que los receptores Trk son una innovación de los vertebrados, y sugieriendo que se originó por barajado de exones contenedores de dominios proteicos. Asímismo la expresión de este gen durante el desarrollo embrionario del anfioxo ha revelado ciertas características novedosas respecto al desarrollo de su sistema nervioso. Durante la neurulación se ha provado la migración individual de células ectodérmicas, lo que podría reflejar un comportamiento parecido al de las células de la cresta neural de vertebrados, un tipo de células pluripotentes que dan lugar a un gran número de estructuras únicamente presentes en los vertebrados y totalmente ausentes en el anfioxo. Este trabajo también incluye la caracterización del primer miembro conocido de la familia de las caspasas en el anfioxo, involucradas en muerte neuronal y, además las primeras técnicas desarrolladas para la obtención rutinaria de embriones, con la potencialidad que ello comporta para su manipulación "in vivo", con el objetivo de realizar ensayos funcionales y abrir las puertas a los estudios de Evo-Devo experimental. / Neurotrophic factors and their receptors play an essential role in the development and maintenance of the vertebrate nervous system, where they crucially contribute to higher neuronal functions such as learning, memory and complex social behaviour. These genes have been studied for the first time in the cephalochordate amphioxus, which is presently the best stand in for the study of one of the major events in evolution: the invertebrate-vertebrate transition. This work describes the molecular and functional characterisation of the first Trk receptor ever isolated from an invertebrate, refuting the idea that Trk receptors are a vertebrate evolutionary novelty. The results obtained suggest that exon shuffling was a key mechanism to generate a unique ProtoTrk gene, similar to that of amphioxus, which subsequently expanded by gene duplication during vertebrate evolution giving rise to all members of the Trk gene family presently known in higher vertebrates. Furthermore, the expression pattern of this Trk receptor throughout embryonic development revealed certain particularities of the amphioxus nervous system never described before. The embryonic epidermis of amphioxus neurulae contains a cell population able to migrate individually, mimicking the migratory behaviour of the vertebrate neural crest cells, a pluripotent cell type only present in vertebrates and totally absent in amphioxus. This work also includes the characterisation of the first caspase ever isolated in amphioxus and the first approaches towards experimental Evo-Devo through the development of new techniques to obtain amphioxus embryos "a la carte" and to manipulate them "in vivo".

Characterization of potassium cation transport systems in the yeast Zygosaccharomyces rouxii Potassium has become absolutely necessary cation for living cells, including yeasts, because it plays several important roles in physiological processes. Intracellular concentration of K+ in yeasts is usually between 200 mM and 300 mM, while the external K+ concentration is ranging from molar to micromolar. To adapt to environments with low K+ content, yeast cells employ various K+ high-affinity uptake systems, e.g. Trk, Hak and K+ -ATPase, that provide cells with the sufficient amount of potassium. The recent release of the complete sequence of the osmotolerant yeast Zygosaccharomyces rouxii genome allowed us to search homologues of the known yeast potassium uptake systems. We have found just one gene encoding a putative potassium transporter homologous to the S. cerevisie TRK1. For the characterisation of transport properties and physiological roles of the product of this gene, named ZrTRK1, three approaches have been used. First, the IT tools serve to analyse sequence characteristics, phylogenetic relationships etc. The second approach involves cloning of the gene and its expression in a S. cerevisiae mutant strain lacking its own two Trk systems, characterisation of transformants' growth phenotypes and...

Dor pélvica crônica (DPC) afeta grande númerode mulheres e seu manejo ainda permanece complexo e insatisfatório. Estudos têm demonstrado um envolvimento do fator de crescimento neuronal (FCN) no processo de cronificação da dor. Participação hormonal neste processo também tem sido aventada, visto autores terem demonstrado influência estro/progestacional sobre nociceptores tanto direta quanto indiretamente através da influência exercida sobre os fatores neurotróficos. Foi objetivo deste estudo, verificar a associação entre a expressão do fator de crescimento neuronal (FCN), seu receptor (trk A) e os receptores de estrogênio e progesterona no peritôneo pélvico com a presença de dor pélvica crônica. Para tal foi realizado um estudo transversal incluindo um grupo de 22 mulheres com DPC, 8 com DPC e usuárias de anticoncepcional oral (DPC/ACO) e 7 sem dor. A dor foi analisada pela escala analógica visual (EAV) e questionário de McGill. Foi realizado imunohistoquímica para avaliar FCN e seu receptor trk A, receptores de estrogênio (RE) e progesterona (RP). A expressão de FCN teve media de 5, variando de 0 a 8, no grupo DPC, 5,5 no grupo DPC/ACO variando 3 a 8, e no grupo sem dor de 5 variando de 3 a 8 (p>0,05). A expressão de trk A apresentou media de 6, variandode 3 a 8, no grupo DPC, 6 no grupo DPC/ACO, variando de 4 a 8, e 6 no grupo sem dor variando de 4 a 6 (p>0,05). A expressão do RE apresentou média 4 no grupo DPC, variando de 0 a 8, 3,5 no grupo DPC/ACO variando de 0 a 8, e 7 no grupo sem dor, variando de 6 a 8 (p<0,05). A expressão do RP teve média 6,5 no grupo DPC, variando de 0 a 8, 5 no grupo DPC/ACO, variando de 0 a 7, e 7 no grupo sem dor, variando de 5 a 8 (p>0,05). Nossos resultados sugerem um papel anti-nociceptivo do estrogênio no peritôneo pélvico de mulheres no menacme, não mediado por expressão de FCN ou trk A. / Chronic pelvic pain (CPP) affects a great number of women and its management still remains complex and unsatisfactory. Studies have shown an involvement of the neuronal growing factor (NGF) in the process of permanence of pain. Hormonal participation in this process has also been put forward, as some authors have demonstrated estro/progestational influence under nociceptors direct or indirectly through their influence on neurotrofic factors. This study aimed to verify the association among the expression of neuronal growing factor (NGF), its receptor (TrKA) and the estrogen and progesterone receptors in the pelvic peritoneum with the presence of chronic pelvic pain. A transversal study was carried out including a group of 22 women with CPP, 8 with CPP and users of oral anticonceptional (CPP/OAC) and 7 without pain. The pain was analized by the visual analogic scale (VAS) and McGill\'s questionnaire. Imunehistochemical was performed to evaluate the NGF and its receptor TrKA, estrogen (ER) and progesteron (PR) receptors. The expression of NGF was an average of 5, varying from 0 to 8, in group CPP, 5,5 in group CPP/ OAC varying from 3 to 8, and in the group without pain varying from 3 to 8 (p>0,05). The expression of TrKA presented an average of 6, varying from 3 to 8, in the group CPP, 6 in the group CPP/OAC, varying from 4 to 8, and 6 in the group without pain varying from 4 to 6 (p>0,05). The expression of ER presented an average of 4 in the group CPP, varying from 0 to 8, 3,5 in group CPP/OAC varying from 0 to 8, and 7 in group without pain, varying from 6 to 8 (p<0,05). The expression of PR had an average 6,5 in the group CPP, varying from 0 to 8,5 in the group CPP/OAC, varying from 0 to 7, and 7 in the group without pain, varying from 5 to 8 (p>0,05). Our studies suggest an anti- nociceptive rule of estrogen in the pelvic peritoneum of women in menacme, not mediated by expression of NGF or TrKA.

Dor pélvica crônica (DPC) afeta grande númerode mulheres e seu manejo ainda permanece complexo e insatisfatório. Estudos têm demonstrado um envolvimento do fator de crescimento neuronal (FCN) no processo de cronificação da dor. Participação hormonal neste processo também tem sido aventada, visto autores terem demonstrado influência estro/progestacional sobre nociceptores tanto direta quanto indiretamente através da influência exercida sobre os fatores neurotróficos. Foi objetivo deste estudo, verificar a associação entre a expressão do fator de crescimento neuronal (FCN), seu receptor (trk A) e os receptores de estrogênio e progesterona no peritôneo pélvico com a presença de dor pélvica crônica. Para tal foi realizado um estudo transversal incluindo um grupo de 22 mulheres com DPC, 8 com DPC e usuárias de anticoncepcional oral (DPC/ACO) e 7 sem dor. A dor foi analisada pela escala analógica visual (EAV) e questionário de McGill. Foi realizado imunohistoquímica para avaliar FCN e seu receptor trk A, receptores de estrogênio (RE) e progesterona (RP). A expressão de FCN teve media de 5, variando de 0 a 8, no grupo DPC, 5,5 no grupo DPC/ACO variando 3 a 8, e no grupo sem dor de 5 variando de 3 a 8 (p>0,05). A expressão de trk A apresentou media de 6, variandode 3 a 8, no grupo DPC, 6 no grupo DPC/ACO, variando de 4 a 8, e 6 no grupo sem dor variando de 4 a 6 (p>0,05). A expressão do RE apresentou média 4 no grupo DPC, variando de 0 a 8, 3,5 no grupo DPC/ACO variando de 0 a 8, e 7 no grupo sem dor, variando de 6 a 8 (p<0,05). A expressão do RP teve média 6,5 no grupo DPC, variando de 0 a 8, 5 no grupo DPC/ACO, variando de 0 a 7, e 7 no grupo sem dor, variando de 5 a 8 (p>0,05). Nossos resultados sugerem um papel anti-nociceptivo do estrogênio no peritôneo pélvico de mulheres no menacme, não mediado por expressão de FCN ou trk A. / Chronic pelvic pain (CPP) affects a great number of women and its management still remains complex and unsatisfactory. Studies have shown an involvement of the neuronal growing factor (NGF) in the process of permanence of pain. Hormonal participation in this process has also been put forward, as some authors have demonstrated estro/progestational influence under nociceptors direct or indirectly through their influence on neurotrofic factors. This study aimed to verify the association among the expression of neuronal growing factor (NGF), its receptor (TrKA) and the estrogen and progesterone receptors in the pelvic peritoneum with the presence of chronic pelvic pain. A transversal study was carried out including a group of 22 women with CPP, 8 with CPP and users of oral anticonceptional (CPP/OAC) and 7 without pain. The pain was analized by the visual analogic scale (VAS) and McGill\'s questionnaire. Imunehistochemical was performed to evaluate the NGF and its receptor TrKA, estrogen (ER) and progesteron (PR) receptors. The expression of NGF was an average of 5, varying from 0 to 8, in group CPP, 5,5 in group CPP/ OAC varying from 3 to 8, and in the group without pain varying from 3 to 8 (p>0,05). The expression of TrKA presented an average of 6, varying from 3 to 8, in the group CPP, 6 in the group CPP/OAC, varying from 4 to 8, and 6 in the group without pain varying from 4 to 6 (p>0,05). The expression of ER presented an average of 4 in the group CPP, varying from 0 to 8, 3,5 in group CPP/OAC varying from 0 to 8, and 7 in group without pain, varying from 6 to 8 (p<0,05). The expression of PR had an average 6,5 in the group CPP, varying from 0 to 8,5 in the group CPP/OAC, varying from 0 to 7, and 7 in the group without pain, varying from 5 to 8 (p>0,05). Our studies suggest an anti- nociceptive rule of estrogen in the pelvic peritoneum of women in menacme, not mediated by expression of NGF or TrKA.

Mevinphos (Mev) is an organophosphate insecticide that acts on the rostral ventrolateral medulla (RVLM), the origin of sympathetic vasomotor tone, to induce cardiovascular responses. This study investigated the role of Trk (tropomyosin-related kinase) (receptor form) or Src (non-receptor form) tyrosine kinase at the RVLM in Mev-induced cardiovascular responses. Bilateral microinjection of Mev (10 nmol) into the RVLM elicited two distinct phases of cardiovascular responses, designated Phase I (sympathoexcitatory) and Phase II (sympathoinhibitory) Mev intoxication. Western blot assay showed that whereas p-Trk490 was increased during Phase I, p-Src416 was increased only during Phase II Mev intoxication. Interestingly, application of a Trk specific inhibitor (K252a; 1 pmol) or Src specific inhibitor (SU6656; 100 pmol) into the bilateral RVLM blunted the Mev-elicited sympathoexcitatory or sympathoinhibitory effect, respectively. Besides, K252a was limited to block NOS I protein expression in the RVLM during Mev intoxication, SU6656 only inhibited NOS II protein expression in the RVLM during Mev intoxication. We conclude that Trk tyrosine kinase (p-Trk490) in the RVLM participates in the Phase I cardiovascular responses during Mev intoxication, Src tyrosine kinase (p-Src416) in the RVLM participates in the Phase II cardiovascular responses associated with Mev intoxication.

No description available.

Οι νευροτροφίνες (ΝΤs), Nerve Growth Factor (NGF), Brain-Derived Neurotrophin Factor (BDNF), NΤ-3, ΝΤ-4, ΝΤ-5 και ΝΤ-6 ανήκουν σε μια οικογένεια πολυπεπτιδικών αυξητικών παραγόντων οι οποίοι απαιτούνται για την ανάπτυξη του νευρικού συστήματος στα σπονδυλωτά. Εμπλέκονται στην επιβίωση, στη διαφοροποίηση, στην ωρίμανση των νευρώνων, στη συναπτική πλαστικότητα, στη μάθηση, στη μνήμη, καθώς επίσης και στην έκφραση και ενεργότητα σημαντικών πρωτεϊνών, όπως ιοντικών καναλιών και νευροδιαβιβαστικών υποδοχέων. Οι λειτουργίες αυτές επιτελούνται μέσω της δέσμευσής τους σε δύο είδη μεμβρανικών υποδοχέων, της οικογένειας κινάσης-τυροσίνης TrkA, TrkB και TrkC (tropomyosinerelated kinase) και του pan-neurotrophin (με ικανότητα δέσμευσης με όλες τις νευροτροφίνες) υποδοχέα p75NTR που είναι μέλος των υποδοχέων Tumor Necrosis Factors (TNFs). Οι νευροτροφίνες εκφράζονται σε κύτταρα του Κ.Ν.Σ. και Π.Ν.Σ. αλλά και σε ιστούς-όργανα εκτός νευρικού συστήματος, όπως είναι η υπόφυση. Σκοπός της εργασίας ήταν να μελετήσουμε την έκφραση των υποδοχέων των νευροτροφινών με σύγχρονες μεθόδους ανοσοϊστοχημείας σε αδενώματα της υπόφυσης και να συσχετίσουμε την έκφρασή τους με τα κλινοκοπαθολογικά χαρακτηριστικά των ασθενών. Όλα τα αδενώματα της μελέτης που συμπεριλήφθησαν στη μελέτη (10ανδρών και 8 γυναικών) εμφάνισαν ανοσοϊστοχημική χρώση για τον υποδοχέα TrkA και συγκεκριμένα έντονη χρώση (+3) τα 9/18 (50%) των περιστατικών, μέτρια χρώση (+2) τα 8/18 (45%) των περιστατικών και ασθενή χρώση (+1) 1/18 (5%) των περιστατικών. Ο υποδοχέας TrkB εμφάνισε θετικότητα στο 83% (15/18) των περιπτώσεων. Τα 6/15 (40%) περιστατικά παρουσίασαν έντονη χρώση (+3), τα 4/15 (27%) περιστατικά μέτρια χρώση (+2) και τα 5/15 (33%) περιστατικά ασθενή χρώση (+1). Ανοσοϊστοχημική χρώση για τον υποδοχέα TrkB παρατηρήθηκε επίσης στα αγγεία 4/15 (27%) των αδενωμάτων. Τα 11/18 (61%) των αδενωμάτων παρουσίασαν ανοσοθετικότητα για τον TrkC και συγκεκριμένα τα 3/11 (27%) περιστατικά εμφάνισαν μέτρια χρώση (+2) και 8/11 (73%) περιστατικά ασθενή (+1). Χρώση για τον υποδοχέα TrkC εντοπίστηκε σε αγγεία σε 4/11 περιστατικά (36%). Τέλος έκφραση για τον p75 υποδοχέα δεν παρατηρήθηκε σε κανένα αδένωμα. Με δεδομένο ότι οι υποδοχείς TrkB και TrkC εκφράζονται στα αγγεία των αδενωμάτων, μελετήθηκε η έκφραση των υποδοχέων των νευροτροφινών σε σχέση με την αγγειογένεση, ένας μηχανισμός που αφορά άμεσα την πρόγνωση και την ανταπόκριση στην αντίστοιχη θεραπεία των όγκων. Μελετήθηκε η έκφραση του CD31(platelet endothelial cell adhesion molecule) και του VEGFR3 (Vascular Endothelial Growth Factor Receptor 3). Ο παράγοντας VEGFR3 συμβάλλει επίσης και στην ανάπτυξη λεμφαγγείων στο στρώμα του όγκου επάγοντας την ανάπτυξή του. Η εκτίμηση της ανοσοεντόπισης για τον CD31 και τον VEGFR3 για κάθε νεόπλασμα έγινε κατόπιν επιλογής τριών αγγειοβριθέστερων περιοχών, την καταμέτρηση των αγγείων σε κάθε περιοχή και τον υπολογισμό του μέσου όρου (MCV Microvessel Count). Για τον παράγοντα VEGFR3 το 89% των περιστατικών ήταν θετικά εμφανίζοντας ένα εύρος MCV της τάξης των 2 έως 32,67, ενώ για τον παράγοντα CD31 το 100% των αδενωμάτων ήταν θετικά με MCV της τάξης των 4,67 έως 53,67. Δεν παρατηρήθηκε συσχέτιση του MCV με την έκφραση των υποδοχέων των νευροτροφινών. Οι υποδοχείς των νευροτροφινών ενώ εκφράζονται στη φυσιολογική υπόφυση συμμετέχοντας στην ανάπτυξη και στην επιβίωση των κυττάρων, δεν «σιωπούν» στα αδενώματά της. Το ερώτημα που γεννάται είναι αν δρουν ως παράγοντες διατήρησης της καλοήθειας ή αν συμβάλλουν στην ογκογένεση και στην μετέπειτα εξέλιξη των νεοπλασμάτων της υπόφυσης. Περαιτέρω μελέτες απαιτούνται για την διερεύνηση του ρόλου των νευροτροφινών μέσω των υποδοχέων τους στα αδενώματα υπόφυσης, στον άνθρωπο. / -