eneurin C-terminal associated peptides (TCAPs) are a novel family of peptides encoded on the last exon of the teneurin genes. The predicted peptide sequences are highly conserved across metazoans and possess the structural hallmarks of a cleavable bioactive peptide that are 40 or 41 amino acid residues. One of the peptides in the family, TCAP-1, is a potent regulator of neurite outgrowth and dendritic spine density in the hippocampus and inhibits corticotropin-releasing factor (CRF)-associated stress-induced and cocaine-seeking behaviours. The effects of TCAP-1 are long lasting, suggesting that TCAP-1 plays a significant role in the regulation of cell-to-cell communication and cellular plasticity. Moreover, TCAP-1 regulates cellular energy, metabolism and cell survival and may, therefore, possess functional attributes outside of the CNS. However, the molecular mechanisms associated with TCAP-1-mediated trophic effects are not known. My research was aimed to 1) determine whether TCAP-1 exerts its effects as part of a direct teneurin-1 function, whereby TCAP-1 represents a functional region of the large teneurin-1 protein, or if it has an independent role, either as a splice variant or post-translational proteolytic cleavage product of teneurin-1; 2) map the distribution of TCAP-1-immunoreactivity and TCAP-1 binding sites in mouse; 3) elucidate the molecular mechanism by which TCAP-1 regulates cytoskeletal dynamics; and 4) investigate a role for TCAP-1 in male reproduction. My research establishes that the C-terminal region of teneurin-1, corresponding to TCAP-1, can be both structurally and functionally independent from teneurin-1 in both the brain and testis of the adult mouse. Furthermore, I provide novel evidence that functionally links the teneurin-TCAP-1 system with the dystroglycan complex and provide new insight into the molecular and signaling mechanisms by which TCAP-1 regulates cytoskeletal dynamics. These studies implicate the teneurins in a broader range of neuroendocrine and trophic functions than previously thought and furthers our understanding of the mechanisms associated with TCAP-1-mediated function in the body.

eneurin C-terminal associated peptides (TCAPs) are a novel family of peptides encoded on the last exon of the teneurin genes. The predicted peptide sequences are highly conserved across metazoans and possess the structural hallmarks of a cleavable bioactive peptide that are 40 or 41 amino acid residues. One of the peptides in the family, TCAP-1, is a potent regulator of neurite outgrowth and dendritic spine density in the hippocampus and inhibits corticotropin-releasing factor (CRF)-associated stress-induced and cocaine-seeking behaviours. The effects of TCAP-1 are long lasting, suggesting that TCAP-1 plays a significant role in the regulation of cell-to-cell communication and cellular plasticity. Moreover, TCAP-1 regulates cellular energy, metabolism and cell survival and may, therefore, possess functional attributes outside of the CNS. However, the molecular mechanisms associated with TCAP-1-mediated trophic effects are not known. My research was aimed to 1) determine whether TCAP-1 exerts its effects as part of a direct teneurin-1 function, whereby TCAP-1 represents a functional region of the large teneurin-1 protein, or if it has an independent role, either as a splice variant or post-translational proteolytic cleavage product of teneurin-1; 2) map the distribution of TCAP-1-immunoreactivity and TCAP-1 binding sites in mouse; 3) elucidate the molecular mechanism by which TCAP-1 regulates cytoskeletal dynamics; and 4) investigate a role for TCAP-1 in male reproduction. My research establishes that the C-terminal region of teneurin-1, corresponding to TCAP-1, can be both structurally and functionally independent from teneurin-1 in both the brain and testis of the adult mouse. Furthermore, I provide novel evidence that functionally links the teneurin-TCAP-1 system with the dystroglycan complex and provide new insight into the molecular and signaling mechanisms by which TCAP-1 regulates cytoskeletal dynamics. These studies implicate the teneurins in a broader range of neuroendocrine and trophic functions than previously thought and furthers our understanding of the mechanisms associated with TCAP-1-mediated function in the body.

Layer II neurons of the entorhinal cortex (ECII) are selectively vulnerable to Alzheimer’s disease (AD). Investigations into the molecular mechanisms of this ECII vulnerability provide unique opportunities to better understanding the pathology of AD. Preliminary data has suggested teneurin-3 (Tenm3) to have a role in this vulnerability due to its ECII enrichment, genetic variants associated with AD, and altered electrophysiology in Tenm3-knockout (KO) mice. In this study, the impacts of Tenm3- KO in mice were further explored. Electron tomography and immunofluorescent confocal microscopy were utilized to compare wild-type (WT) and KO mice’s perforant pathway synaptic densities and structures. A slight trend was found for increased synaptic density in Tenm3-KO mice. The structural changes in Tenm3-KO mice were more pronounced and encompassed alterations to active zones, bouton volumes, and synaptic vesicle pools. Overall, this work suggests Tenm3’s involvement in structural remodeling of both axonal boutons and dendritic spines thus providing a hypothesis for its role in ECII’s selective vulnerability to AD.

Teneurin C-terminal associated peptide-1 (TCAP-1) is a recently characterized peptide that may act as one potential neuroprotective agent as it has been shown to regulate several stress-associated behaviours in rodents and possesses a number of protective actions on cells, however the mechanism remains unknown. Brain-derived neurotrophic factor (BDNF) is a neurotrophin recognized for mediating survival, differentiation, and proliferation. TCAP-1 may act, in part, via BDNF to provide neuroprotection via modulation of BDNF expression. The aim of this research was to further investigate the mechanism of TCAP’s neuroprotective actions. I show that TCAP-1 is neuroprotective and a potent enhancer of cell numbers under varying levels of oxygen. I also establish that TCAP-1 is able to influence neuronal behaviour by differentially regulating neurite growth. In addition, I indicate that TCAP-1 is able to regulate BDNF expression in immortalized mouse hypothalamic N38 cells, which suggests that TCAP-1’s neuroprotective mechanism may involve BDNF.

Teneurin C-terminal associated peptide-1 (TCAP-1) is a recently characterized peptide that may act as one potential neuroprotective agent as it has been shown to regulate several stress-associated behaviours in rodents and possesses a number of protective actions on cells, however the mechanism remains unknown. Brain-derived neurotrophic factor (BDNF) is a neurotrophin recognized for mediating survival, differentiation, and proliferation. TCAP-1 may act, in part, via BDNF to provide neuroprotection via modulation of BDNF expression. The aim of this research was to further investigate the mechanism of TCAP’s neuroprotective actions. I show that TCAP-1 is neuroprotective and a potent enhancer of cell numbers under varying levels of oxygen. I also establish that TCAP-1 is able to influence neuronal behaviour by differentially regulating neurite growth. In addition, I indicate that TCAP-1 is able to regulate BDNF expression in immortalized mouse hypothalamic N38 cells, which suggests that TCAP-1’s neuroprotective mechanism may involve BDNF.

The neuropeptide, corticotropin-releasing factor (CRF), plays a critical role in the central regulation of various stress-related behaviours, including those unique to subjects with prior cocaine experience. The three series of experiments presented in this dissertation explored the role of two neurochemical systems, the teneurin C-terminal associated peptides (TCAP) and the endocannabinoids (eCBs), in several cocaine- and anxiety-related behaviours induced or mediated by CRF. The first series of experiments examined the effects of TCAP-1 on the reinstatement of cocaine seeking and expression of cocaine-induced behavioural sensitization. Repeated (5-day), but not acute, TCAP-1 treatment blocked the reinstatement of cocaine seeking induced by central injections of CRF. TCAP-1 was, however, without effect on footshock- or cocaine-induced reinstatement. Repeated TCAP-1 further interfered with the expression of behavioural sensitization to a CRF, but not a cocaine, challenge. These findings suggest that TCAP-1 normalizes CRF signaling dysregulated by cocaine exposure to interfere in the subsequent effects of CRF on cocaine-related behaviours. A parallel series of experiments investigated the role of eCB signaling at CB1 receptors in the reinstatement of cocaine seeking and cocaine-sensitized locomotion. Pretreatment with the CB1 receptor antagonist, AM251, selectively interfered with CRF-, but not footshock- or cocaine-induced reinstatement. AM251 further blocked the expression of behavioural sensitization induced by challenge injections of both CRF and cocaine. These findings reveal a mediating role for CB1 receptor transmission in the effects of CRF on cocaine-related behaviours. A final series of experiments examined the role of CB1 receptor transmission in the behavioural anxiety induced by central injections of CRF, and by withdrawal from chronic cocaine exposure. AM251, although itself anxiogenic, reversed anxiety induced by CRF and cocaine withdrawal. Furthermore, AM251 elevated plasma corticosterone levels, indicative of increased HPA axis activity, irrespective of CRF treatment or cocaine withdrawal. These findings suggest that CRF- and cocaine withdrawal-induced anxiety are mediated, at least in part, by CB1 receptor transmission, independent of HPA axis regulation. The collective findings are discussed within a framework of CRF-TCAP-eCB interactions, wherein TCAP-1 and AM251 are proposed to act in parallel to modulate amygdalar CRF transmission, and thus regulate the expression of cocaine- and anxiety-related behaviours.

The neuropeptide, corticotropin-releasing factor (CRF), plays a critical role in the central regulation of various stress-related behaviours, including those unique to subjects with prior cocaine experience. The three series of experiments presented in this dissertation explored the role of two neurochemical systems, the teneurin C-terminal associated peptides (TCAP) and the endocannabinoids (eCBs), in several cocaine- and anxiety-related behaviours induced or mediated by CRF. The first series of experiments examined the effects of TCAP-1 on the reinstatement of cocaine seeking and expression of cocaine-induced behavioural sensitization. Repeated (5-day), but not acute, TCAP-1 treatment blocked the reinstatement of cocaine seeking induced by central injections of CRF. TCAP-1 was, however, without effect on footshock- or cocaine-induced reinstatement. Repeated TCAP-1 further interfered with the expression of behavioural sensitization to a CRF, but not a cocaine, challenge. These findings suggest that TCAP-1 normalizes CRF signaling dysregulated by cocaine exposure to interfere in the subsequent effects of CRF on cocaine-related behaviours. A parallel series of experiments investigated the role of eCB signaling at CB1 receptors in the reinstatement of cocaine seeking and cocaine-sensitized locomotion. Pretreatment with the CB1 receptor antagonist, AM251, selectively interfered with CRF-, but not footshock- or cocaine-induced reinstatement. AM251 further blocked the expression of behavioural sensitization induced by challenge injections of both CRF and cocaine. These findings reveal a mediating role for CB1 receptor transmission in the effects of CRF on cocaine-related behaviours. A final series of experiments examined the role of CB1 receptor transmission in the behavioural anxiety induced by central injections of CRF, and by withdrawal from chronic cocaine exposure. AM251, although itself anxiogenic, reversed anxiety induced by CRF and cocaine withdrawal. Furthermore, AM251 elevated plasma corticosterone levels, indicative of increased HPA axis activity, irrespective of CRF treatment or cocaine withdrawal. These findings suggest that CRF- and cocaine withdrawal-induced anxiety are mediated, at least in part, by CB1 receptor transmission, independent of HPA axis regulation. The collective findings are discussed within a framework of CRF-TCAP-eCB interactions, wherein TCAP-1 and AM251 are proposed to act in parallel to modulate amygdalar CRF transmission, and thus regulate the expression of cocaine- and anxiety-related behaviours.

Orientador: Cláudio Aparecido Casatti / Resumo: As teneurinas (Tens) são proteínas transmembrana do tipo II, constituídas de quatro membros homólogos (Ten-1-4). Estas proteínas são expressas principalmente durante a neurogênese do sistema nervoso central (SNC) e estão envolvidas primariamente no estabelecimento dos circuitos neuronais. Tens apresentam vários sítios de clivagens intracelular e extracelular que resultam em peptídeos bioativos, destacando-se os peptídeos associados aos terminais carboxila das teneurinas (Teneurin C-terminal-Associated Peptides, TCAPs). As latrofilinas (LPHN1-3) representam receptores associados à proteína G, sendo os principais receptores endógenos das Tens. A interação da Ten-2 com a LPHN-1 resulta na modulação nos níveis de cálcio intracelular, fato este que pode estar desbalanceado durante episódios epileptogênicos. O principal propósito deste estudo foi verificar possíveis alterações na imunorreatividade e na expressão gênica da Ten-2 no SNC em um modelo de epilepsia induzida por cloreto de lítio-cloridrato de pilocarpina em ratos adultos. Adicionalmente, as expressões gênicas do TCAP-2 e LPHN1 também foram analisadas, visto que são as principais proteínas correlacionadas à Ten-2. Para isto, ratos adultos (Rattus norvegicus; n=49) foram submetidos a indução de status epilepticus (SE) com cloreto de lítio (127 mg/kg) e cloridrato de pilocarpina (40 mg/kg) e divididos em grupos controles, grupos 2, 5 e 14 dias após SE e grupos epilepsia crônica (35 e 75 dias). Amostras do SNC destes animais... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Teneurins (Tens) are a type II transmembrane protein family composed of four homologous members (Ten-1-4). These proteins are primarily present in the central nervous system (CNS) during neurogenesis and exert an important role in the development and establishment of neuronal circuits. Tens have several intra- and extracellular cleavage sites, originating bioactive peptides, such as the carboxyl-terminal peptides named Teneurin C-terminal-Associated Peptides (TCAPs). Latrophilins (LPHN1-3) represent G protein-coupled receptors and are considered the main endogenous receptors for Tens. The Ten-2-LPHN-1interaction results in intracellular calcium modulation in neurons and this system can be changed during epilepsy induction. The main purpose of this study was to verify possible alterations in immunoreactivity and gene expression of Ten-2 in the CNS from an adult rat model of lithium chloridepilocarpine-induced epilepsy. In addition, TCAP-2 and LHPN1 gene expressions were also analyzed, as they are the main Ten-2 related proteins. For this, adult male (Rattus norvegicus; n = 49) were submitted to status epilepticus (SE) induced by intraperitoneal administration of lithium chloride (127 mg/kg) and pilocarpine hydrochloride (40 mg/kg). Subsequently, the animals were divided into control groups, 2-, 5- and 14-day groups after SE, as well as chronic epilepsy group (35-75 days). Samples were submitted to immunohistochemistry technique to identify Teneurin-2-like immunoreactive (Ten-2... (Complete abstract click electronic access below) / Doutor

The teneurin C-terminal associated peptides (TCAP) are a family of four predicted peptides that are expressed in all metazoans where the teneurins have been studied to date. Of the four peptides, TCAP-1 has been studied most extensively. In vitro, TCAP-1 increases neuronal proliferation and neurite outgrowth. In vivo, the peptide reduces CRF-induced behavioural responses in rats. Despite the large body of evidence indicating a strong biological role for TCAP-1, little is known about the chemistry and solubility of the peptide, or the signaling pathway(s) mediating these effects. The aim of this research was to appropriately solubilize the peptide and to develop detection assays for its study in greater detail. I have now established an appropriate formulation of TCAP-1 and developed an immunoassay to assess its concentrations in tissues and in circulation. Also, by examining a number of transcriptional response elements, I have found two assays for probing the signal transduction mechanisms of this peptide.

The teneurin C-terminal associated peptides (TCAP) are a family of four predicted peptides that are expressed in all metazoans where the teneurins have been studied to date. Of the four peptides, TCAP-1 has been studied most extensively. In vitro, TCAP-1 increases neuronal proliferation and neurite outgrowth. In vivo, the peptide reduces CRF-induced behavioural responses in rats. Despite the large body of evidence indicating a strong biological role for TCAP-1, little is known about the chemistry and solubility of the peptide, or the signaling pathway(s) mediating these effects. The aim of this research was to appropriately solubilize the peptide and to develop detection assays for its study in greater detail. I have now established an appropriate formulation of TCAP-1 and developed an immunoassay to assess its concentrations in tissues and in circulation. Also, by examining a number of transcriptional response elements, I have found two assays for probing the signal transduction mechanisms of this peptide.