Regulation of neurite growth in immortalized mouse hypothalamic neurons and rat hippocampal primary cultures by teneurin C-terminal-associated peptide-1

Characterisation of mesenchymal stem cells conditioned media obtained at different conditioning times: their effect on glial cells in in vitro scratch model

In this study, the bone marrow mesenchymal stem cells conditioned media (BMMSC-CM) obtained by conditioning for 24(CM24), 48(CM48) and 72(CM72) hours was characterised. In vitro, the impact of BMMSC-CM on the astrocyte migratory response and oligodendrocyte density was evaluated using the scratch model. The proteomic profiles of individual secretomes were analysed by mass spectrometry and the concentrations of four selected neurotrophins (BDNF, NGF, GDNF and VEGF) were determined by ELISA. Our results revealed an increased number of proteins at CM72, many of which are involved in neuroregenerative processes. ELISA documented a gradual increase in the concentration of two neurotrophins (NGF, VEGF), peaking at CM72. In vitro, the different effect of individual BMMSC-CM on astrocyte migration response and oligodendrocyte density was observed, most pronounced with CM72. The outcomes demonstrate that the prolonged conditioning results in increased release of detectable proteins, neurotrophic factors concentration and stronger effect on reparative processes in neural cell cultures.

A novel role for Teneurin C-terminal Associated Peptide (TCAP) in the regulation of cardiac activity in the Sydney rock oyster, Saccostrea glomerata

Teneurin C-terminal associated peptide (TCAP) is an ancient bioactive peptide that is highly conserved in metazoans. TCAP administration reduces cellular and behavioural stress in vertebrate and urochordate models, yet despite numerous studies in higher animals, there is limited knowledge of its role in invertebrates. In particular, there are no studies on TCAP's effects on the heart of any metazoan, which is a critical organ in the stress response. We used the Sydney rock oyster (SRO) as an invertebrate model to investigate a potential role for sroTCAP in regulating cardiac activity, including during stress. sroTCAP is localized to the neural innervation network of the SRO heart, and suggested binding with various heart proteins related to metabolism and stress, including SOD, GAPDH and metabotropic glutamate receptor. Intramuscular injection of sroTCAP (10 pmol) significantly altered the expression of heart genes that are known to regulate remodelling processes under different conditions, and modulated several gene families responsible for stress mitigation. sroTCAP (1 and 10 pmol) was shown to cause transient bradycardia (heart rate was reduced by up to 63% and for up to 40 min post-administration), indicative of an unstressed state. In summary, this study has established a role for a TCAP in the regulation of cardiac activity through modulation of physiological and molecular components associated with energy conservation, stress and adaptation. This represents a novel function for TCAP and may have implications for higher-order metazoans.

Skeletal muscle metabolism and contraction performance regulation by teneurin C-terminal-associated peptide-1

Skeletal muscle regulation is responsible for voluntary muscular movement in vertebrates. The genes of two essential proteins, teneurins and latrophilins (LPHN), evolving in ancestors of multicellular animals form a ligand-receptor pair, and are now shown to be required for skeletal muscle function. Teneurins possess a bioactive peptide, termed the teneurin C-terminal associated peptide (TCAP) that interacts with the LPHNs to regulate skeletal muscle contractility strength and fatigue by an insulin-independent glucose importation mechanism in rats. CRISPR-based knockouts and siRNA-associated knockdowns of LPHN-1 and-3 in the C2C12 mouse skeletal cell line shows that TCAP stimulates an LPHN-dependent cytosolic Ca2+ signal transduction cascade to increase energy metabolism and enhance skeletal muscle function via increases in type-1 oxidative fiber formation and reduce the fatigue response. Thus, the teneurin/TCAP-LPHN system is presented as a novel mechanism that regulates the energy requirements and performance of skeletal muscle.

Role of Teneurin C-Terminal Associated Peptides (TCAP) on Intercellular Adhesion and Communication

The teneurin C-terminal associated peptides (TCAP) are encoded by the terminal exon of all metazoan teneurin genes. Evidence supports the liberation of a soluble TCAP peptide either by proteolytic cleavage from the mature transmembrane teneurin protein or by a separately transcribed mRNA. Synthetic versions of TCAP, based on its genomic structure, are efficacious at regulating intercellular communication by promoting neurite outgrowth and increasing dendritic spine density in vitro and in vivo in rodent models. This is achieved through cytoskeletal re-arrangement and metabolic upregulation. The putative receptors for TCAPs are the latrophilin (LPHN) family of adhesion G-protein coupled receptors, which facilitate TCAP’s actions through G-proteins associated with cAMP and calcium-regulating signalling pathways. The teneurin/TCAP and latrophilin genes are phylogenetically ancient, likely serving primitive functions in cell adhesion and energy regulation which have been since adapted for a more complex role in synaptogenesis in vertebrate nervous systems.

Teneurin and TCAP Phylogeny and Physiology: Molecular Analysis, Immune Activity, and Transcriptomic Analysis of the Stress Response in the Sydney Rock Oyster (Saccostrea glomerata) Hemocytes

Teneurin C-terminal associated peptide (TCAP) is an ancient bioactive peptide that is highly conserved in metazoans. TCAP administration reduces cellular and behavioral stress in vertebrate and urochordate models. There is little information for invertebrates regarding the existence or function of a TCAP. This study used the Sydney rock oyster (SRO) as a molluscan model to characterize an invertebrate TCAP, from molecular gene analysis to its physiological effects associated with hemocyte phagocytosis. We report a single teneurin gene (and 4 teneurin splice variants), which encodes a precursor with TCAP that shares a vertebrate-like motif, and is similar to that of other molluscan classes (gastropod, cephalopod), arthropods and echinoderms. TCAP was identified in all SRO tissues using western blotting at 1-2 different molecular weights (~22 kDa and ~37kDa), supporting precursor cleavage variation. In SRO hemolymph, TCAP was spatially localized to the cytosol of hemocytes, and with particularly high density immunoreactivity in granules. Based on 'pull-down' assays, the SRO TCAP binds to GAPDH, suggesting that TCAP may protect cells from apoptosis under oxidative stress. Compared to sham injection, the intramuscular administration of TCAP (5 pmol) into oysters modulated their immune system by significantly reducing hemocyte phagocytosis under stress conditions (low salinity and high temperature). TCAP administration also significantly reduced hemocyte reactive oxygen species production at ambient conditions and after 48 h stress, compared to sham injection. Transcriptomic hemocyte analysis of stressed oysters administered with TCAP demonstrated significant changes in expression of genes associated with key metabolic, protective and immune functions. In summary, this study established a role for TCAP in oysters through modulation of physiological and molecular functions associated with energy conservation, stress and cellular defense.

Teneurins: Role in Cancer and Potential Role as Diagnostic Biomarkers and Targets for Therapy

Teneurins have been identified in vertebrates as four different genes (TENM1-4), coding for membrane proteins that are mainly involved in embryonic and neuronal development. Genetic studies have correlated them with various diseases, including developmental problems, neurological disorders and congenital general anosmia. There is some evidence to suggest their possible involvement in cancer initiation and progression, and drug resistance. Indeed, mutations, chromosomal alterations and the deregulation of teneurins expression have been associated with several tumor types and patient survival. However, the role of teneurins in cancer-related regulatory networks is not fully understood, as both a tumor-suppressor role and pro-tumoral functions have been proposed, depending on tumor histotype. Here, we summarize and discuss the literature data on teneurins expression and their potential role in different tumor types, while highlighting the possibility of using teneurins as novel molecular diagnostic and prognostic biomarkers and as targets for cancer treatments, such as immunotherapy, in some tumors.

Synthetic Peptides as Therapeutic Agents: Lessons Learned From Evolutionary Ancient Peptides and Their Transit Across Blood-Brain Barriers

Peptides play a major role in the transmission of information to and from the central nervous system. However, because of their structural complexity, the development of pharmacological peptide-based therapeutics has been challenged by the lack of understanding of endogenous peptide evolution. The teneurin C-terminal associated peptides (TCAP) possess many of the required attributes of a practical peptide therapeutic. TCAPs, associated with the teneurin transmembrane proteins that bind to the latrophilins, members of the Adhesion family of G-protein-coupled receptors (GPCR). Together, this ligand-receptor unit plays an integral role in synaptogenesis, neurological development, and maintenance, and is present in most metazoans. TCAP has structural similarity to corticotropin-releasing factor (CRF), and related peptides, such as calcitonin and the secretin-based peptides and inhibits the (CRF)-associated stress response. Latrophilins are structurally related to the secretin family of GPCRs. TCAP is a soluble peptide that crosses the blood-brain barrier and regulates glucose transport into the brain. We posit that TCAP represents a phylogenetically older peptide system that evolved before the origin of the CRF-calcitonin-secretin clade of peptides and plays a fundamental role in the regulation of cell-to-cell energy homeostasis. Moreover, it may act as a phylogenetically older peptide system that evolved as a natural antagonist to the CRF-mediated stress response. Thus, TCAP's actions on the CNS may provide new insights into the development of peptide therapeutics for the treatment of CNS disorders.

Activity of the Carboxy-Terminal Peptide Region of the Teneurins and Its Role in Neuronal Function and Behavior in Mammals

Teneurin C-terminal associated peptides (TCAPs) are an evolutionarily ancient family of 40- to 41-residue bioactive peptides located on the extracellular end of each of the four teneurin transmembrane proteins. TCAP-1 may exist as a tethered peptide at the teneurin-1 carboxy end or as an independent peptide that is either released via post-transcriptional cleavage from its teneurin-1 pro-protein or independently expressed as its own mRNA. In neurons, soluble TCAP-1 acts as a paracrine factor to regulate cellular activity and neuroplastic interactions. In vitro studies indicate that, by itself, synthetic TCAP-1 promotes neuron growth and protects cells from chemical insult. In vivo, TCAP-1 increases hippocampal neuron spine density, reduces stress-induced behavior and ablates cocaine-seeking behaviors. Together, these studies suggest that the physiological effects of TCAP-1 are a result of an inhibition of corticotropin-releasing factor (CRF) activity leading to increased energy production. This hypothesis is supported by in vivo functional positron emissions tomography studies, which demonstrate that TCAP-1 significantly increases glucose uptake in rat brain. Complimentary in vitro studies show that enhanced glucose uptake is the result of TCAP-1-induced insertion of the glucose transporter into the neuronal plasma membrane, leading to increased glucose uptake and ATP production. Interestingly, TCAP-1-mediated glucose uptake occurs through a novel insulin-independent pathway. This review will focus on examining the role of TCAP on neuronal energy metabolism in the central nervous system.

A Putative Role of Teneurin-2 and Its Related Proteins in Astrocytes

Teneurins are type II transmembrane proteins comprised of four phylogenetically conserved homologs (Ten-1-4) that are highly expressed during neurogenesis. An additional bioactive peptide named teneurin C-terminal-associated peptide (TCAP-1-4) is present at the carboxyl terminal of teneurins. The possible correlation between the Ten/TCAP system and brain injuries has not been explored yet. Thus, this study examined the expression of these proteins in the cerebral cortex after mechanical brain injury. Adult rats were subjected to cerebral cortex injury by needle-insertion lesion and sacrificed at various time points. This was followed by analysis of the lesion area by immunohistochemistry and conventional RT-PCR techniques. Control animals (no brain injury) showed only discrete Ten-2-like immunoreactive pyramidal neurons in the cerebral cortex. In contrast, Ten-2 immunoreactivity was significantly up-regulated in the reactive astrocytes in all brain-injured groups (p < 0.0001) when compared to the control group. Interestingly, reactive astrocytes also showed intense immunoreactivity to LPHN-1, an endogenous receptor for the Ten-2 splice variant named Lasso. Semi-quantitative analysis of Ten-2 and TCAP-2 expression revealed significant increases of both at 48 h, 3 days and 5 days (p < 0.0001) after brain injury compared to the remaining groups. Immortalized cerebellar astrocytes were also evaluated for Ten/TCAP expression and intracellular calcium signaling by fluorescence microscopy after TCAP-1 treatment. Immortalized astrocytes expressed additional Ten/TCAP homologs and exhibited significant increases in intracellular calcium concentrations after TCAP-1 treatment. This study is the first to demonstrate that Ten-2/TCAP-2 and LPHN-1 are upregulated in reactive astrocytes after a mechanical brain injury. Immortalized cerebellar astrocytes expressed Ten/TCAP homologs and TCAP-1 treatment stimulated intracellular calcium signaling. These findings disclose a new functional role of the Ten/TCAP system in astrocytes during tissue repair of the CNS.

Latrophilins: A Neuro-Centric View of an Evolutionary Conserved Adhesion G Protein-Coupled Receptor Subfamily

The adhesion G protein-coupled receptors latrophilins have been in the limelight for more than 20 years since their discovery as calcium-independent receptors for α-latrotoxin, a spider venom toxin with potent activity directed at neurotransmitter release from a variety of synapse types. Latrophilins are highly expressed in the nervous system. Although a substantial amount of studies has been conducted to describe the role of latrophilins in the toxin-mediated action, the recent identification of endogenous ligands for these receptors helped confirm their function as mediators of adhesion events. Here we hypothesize a role for latrophilins in inter-neuronal contacts and the formation of neuronal networks and we review the most recent information on their role in neurons. We explore molecular, cellular and behavioral aspects related to latrophilin adhesion function in mice, zebrafish, Drosophila melanogaster and Caenorhabditis elegans, in physiological and pathophysiological conditions, including autism spectrum, bipolar, attention deficit and hyperactivity and substance use disorders.

Teneurin Structures Are Composed of Ancient Bacterial Protein Domains

Pioneering bioinformatic analysis using sequence data revealed that teneurins evolved from bacterial tyrosine-aspartate (YD)-repeat protein precursors. Here, we discuss how structures of the C-terminal domain of teneurins, determined using X-ray crystallography and electron microscopy, support the earlier findings on the proteins’ ancestry. This chapter describes the structure of the teneurin scaffold with reference to a large family of teneurin-like proteins that are widespread in modern prokaryotes. The central scaffold of modern eukaryotic teneurins is decorated by additional domains typically found in bacteria, which are re-purposed in eukaryotes to generate highly multifunctional receptors. We discuss how alternative splicing contributed to further diversifying teneurin structure and thereby function. This chapter traces the evolution of teneurins from a structural point of view and presents the state-of-the-art of how teneurin function is encoded by its specific structural features.

Latrophilins and Teneurins in Invertebrates: No Love for Each Other?

Transsynaptic connections enabling cell–cell adhesion and cellular communication are a vital part of synapse formation, maintenance and function. A recently discovered interaction between the Adhesion GPCRs Latrophilins and the type II single transmembrane proteins Teneurins at mammalian synapses is vital for synapse formation and dendrite branching. While the understanding of the effects and the molecular interplay of this Latrophilin-Teneurin partnership is not entirely understood, its significance is highlighted by behavioral and neurological phenotypes in various animal models. As both groups of molecules, Latrophilins and Teneurins, are generally highly conserved, have overlapping expression and often similar functions across phyla, it can be speculated that this interaction, which has been proven essential in mammalian systems, also occurs in invertebrates to control shaping of synapses. Knowledge of the generality of this interaction is especially of interest due to its possible involvement in neuropathologies. Further, several invertebrates serve as model organisms for addressing various neurobiological research questions. So far, an interaction of Latrophilins and Teneurins has not been observed in invertebrates, but our knowledge on both groups of molecules is by far not complete. In this review, we give an overview on existing experimental evidence arguing for as well as against a potential Latrophilin-Teneurin interaction beyond mammals. By combining these insights with evolutionary aspects on each of the interaction partners we provide and discuss a comprehensive picture on the functions of both molecules in invertebrates and the likeliness of an evolutionary conservation of their interaction.

Early-life stress impairs developmental programming in Cadherin 13 (CDH13)-deficient mice

OBJECTIVE

Cadherin-13 (CDH13), a member of the calcium-dependent cell adhesion molecule family, has been linked to neurodevelopmental disorders, including autism spectrum (ASD) and attention-deficit/hyperactivity (ADHD) disorders, but also to depression. In the adult brain, CDH13 expression is restricted e.g. to the presynaptic compartment of inhibitory GABAergic synapses in the hippocampus and Cdh13 knockout mice show an increased inhibitory drive onto hippocampal CA1 pyramidal neurons, leading to a shift in excitatory/inhibitory balance. CDH13 is also moderating migration of serotonergic neurons in the dorsal raphe nucleus, establishing projections preferentially to the thalamus and cerebellum during brain development. Furthermore, CDH13 is upregulated by chronic stress as well as in depression, suggesting a role in early-life adaptation to stressful experience. Here, we therefore investigated the interaction between Cdh13 variation and neonatal maternal separation (MS) in mice.

METHODS

Male and female wild-type (Cdh13^+/+), heterozygous (Cdh13^+/-) and homozygous (Cdh13^-/-) knockout mice exposed to MS, or daily handling as control, were subjected to a battery of behavioural tests to assess motor activity, learning and memory as well as anxiety-like behaviour. A transcriptome analysis of the hippocampus was performed in an independent cohort of mice which was exposed to MS or handling, but remained naïve for behavioural testing.

RESULTS

MS lead to increased anxiety-like behaviour in Cdh13^-/- mice compared to the other two MS groups. Cdh13^-/- mice showed a context-dependent effect on stress- and anxiety-related behaviour, impaired extinction learning following contextual fear conditioning and decreased impulsivity, as well as a mild decrease in errors in the Barnes maze and reduced risk-taking in the light-dark transition test after MS. We also show sex differences, with increased locomotor activity in female Cdh13^-/- mice, but unaltered impulsivity and activity in male Cdh13^-/- mice. Transcriptome analysis revealed several pathways associated with cell surface/adhesion molecules to be altered following Cdh13 deficiency, together with an influence on endoplasmic reticulum function.

CONCLUSION

MS resulted in increased stress resilience, increased exploration and an overall anxiolytic behavioural phenotype in male Cdh13^+/+ and Cdh13^+/- mice. Cdh13 deficiency, however, obliterated most of the effects caused by early-life stress, with Cdh13^-/- mice exhibiting delayed habituation, no reduction of anxiety-like behaviour and decreased fear extinction. Our behavioural findings indicate a role of CDH13 in the programming of and adaptation to early-life stress. Finally, our transcriptomic data support the view of CDH13 as a neuroprotective factor as well as a mediator in cell-cell interactions, with an impact on synaptic plasticity.

Teneurins and Teneurin C-Terminal Associated Peptide (TCAP) in Metabolism: What's Known in Fish?

Teneurins have well established roles in function and maintenance of the central nervous systems of vertebrates. In addition, teneurin c-terminal associated peptide (TCAP), a bioactive peptide found on the c-terminal portion of teneurins, has been shown to regulate glucose metabolism. Although, the majority of research conducted on the actions of teneurins and TCAPs has strictly focused on neurological systems in rodents, TCAP was first identified in rainbow trout after screening trout hypothalamic cDNA. This suggests a conserved functional role of TCAP across vertebrates, however, the current depth of literature on teneurins and TCAPs in fish is limited. In addition, the overall function of TCAP in regulating metabolism is unclear. This review will highlight work that has been conducted specifically in fish species in relation to the teneurin system and metabolism in order to identify areas of research that are needed for future work.

Structural Basis for Teneurin Function in Circuit-Wiring: A Toxin Motif at the Synapse

Teneurins (TENs) are cell-surface adhesion proteins with critical roles in tissue development and axon guidance. Here, we report the 3.1-Å cryoelectron microscopy structure of the human TEN2 extracellular region (ECR), revealing a striking similarity to bacterial Tc-toxins. The ECR includes a large β barrel that partially encapsulates a C-terminal domain, which emerges to the solvent through an opening in the mid-barrel region. An immunoglobulin (Ig)-like domain seals the bottom of the barrel while a β propeller is attached in a perpendicular orientation. We further show that an alternatively spliced region within the β propeller acts as a switch to regulate trans-cellular adhesion of TEN2 to latrophilin (LPHN), a transmembrane receptor known to mediate critical functions in the central nervous system. One splice variant activates trans-cellular signaling in a LPHN-dependent manner, whereas the other induces inhibitory postsynaptic differentiation. These results highlight the unusual structural organization of TENs giving rise to their multifarious functions.

Teneurin C-Terminal Associated Peptide (TCAP)-1 and Latrophilin Interaction in HEK293 Cells: Evidence for Modulation of Intercellular Adhesion

The teneurins are a family of four transmembrane proteins essential to intercellular adhesion processes, and are required for the development and maintenance of tissues. The Adhesion G protein-coupled receptor (GPCR) subclass latrophilins (ADGRL), or simply the latrophilins (LPHN), are putative receptors of the teneurins and act, in part, to mediate intercellular adhesion via binding with the teneurin extracellular region. At the distal tip of the extracellular region of each teneurin lies a peptide sequence termed the teneurin C-terminal associated peptide (TCAP). TCAP-1, associated with teneurin-1, is itself bioactive, suggesting that TCAP is a critical functional region of teneurin. However, the role of TCAP-1 has not been established with respect to its ability to interact with LPHN to induce downstream effects. To establish that TCAP-1 binds to LPHN1, a FLAG-tagged hormone binding domain (HBD) of LPHN1 and a GFP-tagged TCAP-1 peptide were co-expressed in HEK293 cells. Both immunoreactive epitopes were co-localized as a single band after immunoprecipitation, indicating an association between the two proteins. Moreover, fluorescent co-labeling occurred at the plasma membrane of LPHN1 over-expressing cells when treated with a FITC-tagged TCAP-1 variant. Expression of LPHN1 and treatment with TCAP-1 modulated the actin-based cytoskeleton in these cells in a manner consistent with previously reported actions of TCAP-1 and affected the overall morphology and aggregation of the cells. This study indicates that TCAP-1 may associate directly with LPHN1 and could play a role in the modulation of cytoskeletal organization and intercellular adhesion and aggregation via this interaction.

A novel role of the corticotrophin-releasing hormone regulating peptide, teneurin C-terminal associated peptide 1, on glucose uptake into the brain

Teneurin C-terminal associated peptide (TCAP) is an ancient paracrine signalling agent that evolved via lateral gene transfer from prokaryotes into an early metazoan ancestor. Although it bears structural similarity to corticotrophin-releasing hormone (CRH), it inhibits the in vivo actions of CRH. The TCAPs are highly expressed in neurones, where they induce rapid cytoskeletal rearrangement and are neuroprotective. Because these processes are highly energy-dependent, this suggests that TCAP has the potential to regulate glucose uptake because glucose is the primary energy substrate in brain, and neurones require a steady supply to meet the high metabolic demands of neuronal communication. Therefore, the objective of the present study was to assess the effect of TCAP-mediated glucose uptake in the brain and in neuronal cell models. TCAP-mediated ¹⁸ F-deoxyglucose (FDG) uptake into brain tissue was assessed in male wild-type Wistar rats by functional positron emission tomography. TCAP-1 increased FDG uptake by over 40% into cortical regions of the brain, demonstrating that TCAP-1 can significantly enhance glucose supply. Importantly, a single nanomolar injection of TCAP-1 increased brain glucose after 3 days and decreased blood glucose after 1 week. This is corroborated by a decreased serum concentration of insulin and an increased serum concentration of glucagon. In immortalised hypothalamic neurones, TCAP-1 increased ATP production and enhanced glucose uptake by increasing glucose transporter recruitment to the plasma membrane likely via AKT and mitogen-activated protein kinase/ERK phosphorylation events. Taken together, these data demonstrate that TCAP-1 increases glucose metabolism in neurones, and may represent a peptide signalling agent that regulated glucose uptake before insulin and related peptides.

Structures of Teneurin adhesion receptors reveal an ancient fold for cell-cell interaction

Teneurins are ancient cell–cell adhesion receptors that are vital for brain development and synapse organisation. They originated in early metazoan evolution through a horizontal gene transfer event when a bacterial YD-repeat toxin fused to a eukaryotic receptor. We present X-ray crystallography and cryo-EM structures of two Teneurins, revealing a ~200 kDa extracellular super-fold in which eight sub-domains form an intricate structure centred on a spiralling YD-repeat shell. An alternatively spliced loop, which is implicated in homophilic Teneurin interaction and specificity, is exposed and thus poised for interaction. The N-terminal side of the shell is ‘plugged’ via a fibronectin-plug domain combination, which defines a new class of YD proteins. Unexpectedly, we find that these proteins are widespread amongst modern bacteria, suggesting early metazoan receptor evolution from a distinct class of proteins, which today includes both bacterial proteins and eukaryotic Teneurins.

Teneurins are cell-cell adhesion receptors that evolved through horizontal gene transfer in which a bacterial YD-repeat protein fused to a eukaryotic receptor. Here the authors present crystallographic and cryo-EM structures of two Teneurins, revealing an ancient YD-repeat protein super-fold.

Teneurin-2 presence in rat and human odontoblasts

Teneurins are transmembrane proteins consisting of four paralogues (Ten-1-4), notably expressed in the central nervous system during development. All teneurins contain a bioactive peptide in their carboxyl terminal named teneurin C-terminal associated peptide (TCAP). The present study analyzed the detailed distribution of teneurin-2-like immunoreactive (Ten-2-LI) cells in developing and mature rat molar teeth, as well as in mature human dental pulps. Ten-2 and TCAP-2 genic expressions were also evaluated in rat and human dental pulps. Finally, Ten-2-LI cells were analyzed during the repair process after dentin-pulp complex injury in rat lower molar teeth. For this, histological sections of rat molar teeth and human dental pulps were submitted to immunohistochemical techniques, while total RNA from developing rat teeth and mature human dental pulps were submitted to conventional RT-PCR. Ten-2-LI cells were evident in the initial bell stage of rat molar teeth development, especially in ectomesenchymal cells of the dental papilla. Ten-2-LI odontoblasts showed strong immunoreactivity in rat and human mature teeth. Ten-2 and TCAP-2 genic expressions were confirmed in rat and human dental pulps. Dentin-pulp complex injury resulted in a decrease of Ten-2-LI odontoblasts after traumatic injury. Interestingly, Ten-2-LI cells were also evident in the pulp cell-rich zone in all postoperative days. In conclusion, Ten-2-LI presence in rat and human odontoblasts was demonstrated for the first time and Ten-2/TCAP-2 genic expressions were confirmed in rat and human dental pulps. Furthermore, it was revealed that Ten-2-LI rat odontoblasts can be modulated during the regenerative process.

Cold-inducible RBM3 inhibits PERK phosphorylation through cooperation with NF90 to protect cells from endoplasmic reticulum stress

The cold-inducible RNA-binding motif protein 3 (RBM3) is involved in the protection of neurons in hypoxic-ischemic and neurodegenerative disorders. RBM3 belongs to a small group of proteins whose synthesis increases during hypothermia while global protein production is slowed down. To investigate the molecular mechanisms underlying RBM3 action, we subjected hippocampal organotypic slice cultures from RBM3 knockout mice to various stressors and found exuberant signaling of the endoplasmic reticulum (ER) stress pathway PRKR-like ER kinase (PERK)-eukaryotic translation initiation factor 2α (eIF2α)-CCAAT/enhancer-binding protein homologous protein (CHOP) as compared with wild-type mice. Further, blocking RBM3 expression in human embryonic kidney HEK293 cells by specific small interfering RNAs increased phosphorylation of PERK and eIF2α, whereas overexpression of RBM3 prevented PERK-eIF2α-CHOP signaling during ER stress induced by thapsigargin or tunicamycin. RBM3 did not affect expression of the ER stress sensor immunoglobulin binding protein/GRP78. However, based on affinity purification coupled with mass spectrometry, coimmunoprecipitation, and proximity ligation assay, we revealed that nuclear factor 90 (NF90) is a novel protein interactor of PERK and that this interaction is essential for RBM3-mediated regulation of PERK activity, which requires an RNA-dependent interaction. In conclusion, our data provide evidence for a central role of RBM3 in preventing cell death by inhibiting the PERK-eIF2α-CHOP ER stress pathway through cooperation with NF90.

On the Teneurin track: a new synaptic organization molecule emerges

To achieve proper synaptic development and function, coordinated signals must pass between the pre- and postsynaptic membranes. Such transsynaptic signals can be comprised of receptors and secreted ligands, membrane associated receptors, and also pairs of synaptic cell adhesion molecules. A critical open question bridging neuroscience, developmental biology, and cell biology involves identifying those signals and elucidating how they function. Recent work in Drosophila and vertebrate systems has implicated a family of proteins, the Teneurins, as a new transsynaptic signal in both the peripheral and central nervous systems. The Teneurins have established roles in neuronal wiring, but studies now show their involvement in regulating synaptic connections between neurons and bridging the synaptic membrane and the cytoskeleton. This review will examine the Teneurins as synaptic cell adhesion molecules, explore how they regulate synaptic organization, and consider how some consequences of human Teneurin mutations may have synaptopathic origins.

Characterization of the teneurin C-terminal associated peptide (TCAP) in the vase tunicate, Ciona intestinalis: A novel peptide system associated with energy metabolism and reproduction

The vase tunicate, Ciona intestinalis, is a protochordate and is considered a sister lineage to the chordates. The recent sequencing of its genome has made this species a particularly important model to understand the genetic basis of vertebrate evolution. However, C. intestinalis is also a highly invasive species along the Atlantic coast of North America and other regions of the world which have caused considerable economic stress due to its biofouling actions and, in particular, negative impacts on the mussel- and oyster-based aquaculture industry. Despite this background, little is known about C. intestinalis physiology. The teneurin C-terminal associated peptides (TCAP) are a family of highly conserved peptide hormones found in most metazoans. Moreover, these peptides have been implicated in the inhibition of stress and stimulation of feeding-based metabolism. We have, therefore, identified this peptide using an in silico approach and characterized its immunological expression in tissues using a mouse polyclonal antiserum. These data indicate that its primary structure is more similar to invertebrate TCAPs relative to vertebrate TCAPs. Immunological expression indicates that it is highly expressed in the digestive tract and gonads consistent with findings in vertebrates. Synthetic mouse TCAP-1 administered into the brachial basket significantly increases the incidence of non-stress contractile behaviors. These findings support the hypothesis that TCAP is a bioactive peptide in C. intestinalis. Thus, C. intestinalis and tunicates in general may offer a simple model to investigate peptide interaction while providing information on how to control this invasive species.

Ancient interaction between the teneurin C-terminal associated peptides (TCAP) and latrophilin ligand-receptor coupling: a role in behavior

Teneurins are multifunctional transmembrane proteins that are found in all multicellular animals and exist as four paralogous forms in vertebrates. They are highly expressed in the central nervous system, where they exert their effects, in part, by high-affinity binding to latrophilin (LPHN), a G-protein coupled receptor (GPCR) related to the adhesion and secretin GPCR families. The teneurin C-terminal associated peptides (TCAPs) are encoded by the terminal exon of all four teneurins, where TCAPs 1 and 3 are independently transcribed as soluble peptides, and TCAPs 2 and 4 remain tethered to their teneurin proprotein. Synthetic TCAP-1 interacts with LPHN, with an association with β-dystroglycan, to induce a tissue-dependent signal cascade to modulate cytoskeletal dynamics. TCAP-1 reduces stress-induced behaviors associated with anxiety, addiction and depression in a variety of models, in part, by regulating synaptic plasticity. Therefore, the TCAP-1-teneurin-LPHN interaction represents a novel receptor-ligand model and may represent a key mechanism underlying the association of behavior and neurological conditions.

Teneurins and Alzheimer's disease: a suggestive role for a unique family of proteins

Alzheimer's disease is a debilitating age-related disorder characterized by distinct pathological hallmarks, such as progressive memory loss and cognitive impairment. During the last few years, several cellular signaling pathways have been associated with the pathogenesis of Alzheimer's disease, such as Notch, mTOR and Wnt. However, the potential factors that modulate these pathways and novel molecular mechanisms that might account for the pathogenesis of Alzheimer's disease or for therapy against this disease are still matters of intense research. Teneurins are members of a unique protein system that has recently been proposed as a novel and highly conserved regulatory signaling system in the vertebrate brain, so far related with neurite outgrowth and neuronal matching. The similitude in structure and function of teneurins with other cellular signaling pathways, suggests that they may play a critical role in Alzheimer's disease, either through the modulation of transcription factors due to the nuclear translocation of the teneurins intracellular domain, or through the activity of the corticotrophin releasing factor (CRF)-like peptide sequence, called teneurin C-terminal associated peptide. Moreover, the presence of Ca(2+)-binding motifs within teneurins structure and the Zic2-mediated Wnt/β-catenin signaling modulation, allows hypothesize a potential crosslink between teneurins and the Wnt signaling pathway, particularly. Herein, we aim to highlight the main characteristics of teneurins and propose, based on current knowledge of this family of proteins, an interesting review of their potential involvement in Alzheimer's disease.

The teneurins: new players in the generation of visual topography

A functionally critical feature of the nervous system is the precision of its connectivity. An emerging molecular mediator of this process is the teneurin/ten-m/odz family of transmembrane proteins. A number of recent studies have provided compelling evidence that teneurins have homophilic adhesive properties which, together with their corresponding expression patterns in interconnected groups of neurons, enables them to promote appropriate patterns of connectivity. Particularly important roles have been demonstrated in the visual, olfactory and motor systems. This review attempts to relate new insights into the complex biology of these molecules to their roles in the establishment of functional neural circuits.

Teneurin C-terminal associated peptides (TCAP): modulators of corticotropin-releasing factor (CRF) physiology and behavior

The existence of the teneurin C-terminal associated peptides (TCAP) was reported in 2004 after screening a rainbow trout hypothalamic cDNA for corticotropin-releasing factor (CRF)-related homologs. In vertebrates, there are four TCAP paralogs, where each peptide is associated with a teneurin transmembrane protein. The TCAPs are 40 or 41 amino acids in length and possess less than 20% residue identity with the CRF family of paralogs. Orthologs of TCAP are found in all metazoans with the possible exception of poriferans and cnidarians. Recent evidence indicates that TCAP and the teneurins may have been introduced into the Metazoa via horizontal gene transfer from prokaryotes into a basal protistan. Thus, the origin of the TCAPs likely predated that of the CRF family. In the mammalian brain, TCAP-1 is transcribed independently from teneurin-1. Moreover, TCAP-1 acts on neurons by a CRF-receptor independent signal transduction pathway to regulate cellular cytoskeletal function to stimulate cell activity. Administration of synthetic TCAP-1 to rodents inhibits a number of CRF- and stress-associated behaviors via a hypothalamic–pituitary–adrenal (HPA) axis-independent mechanism.

Origin of chordate peptides by horizontal protozoan gene transfer in early metazoans and protists: evolution of the teneurin C-terminal associated peptides (TCAP)

The teneurin C-terminal associated peptides (TCAP) are found at the extracellular face in C-terminal region of the teneurin transmembrane proteins. One of these peptides, TCAP-1 is independently transcribed as a smaller bioactive peptide that possesses a number of stress response-attenuating activities. The teneurin-TCAP system appears to be the result of a horizontal gene transfer from a prokaryotic proteinaceous polymorphic toxin to a choanoflagellate. In a basal metazoan, the TCAP region has been modified from a toxin to a soluble intercellular signaling system. New studies indicate that the teneurin-TCAP system form a complex signaling system associated with adhesion, cytoskeletal regulation and intracellular signaling. TCAP-1 is highly conserved in all vertebrates and in mammals, inhibits corticotropin-releasing factor (CRF)-associated stress. Using the TCAP-teneurin system as a model, it is likely that numerous peptide systems in the Chordata began as a result of horizontal gene transfer from prokaryotes early in metazoan ancestry.

C-terminal processing of the teneurin proteins: independent actions of a teneurin C-terminal associated peptide in hippocampal cells

Many neuropsychiatric conditions have a common set of neurological substrates associated with the integration of sensorimotor processing. The teneurins are a recently described family of proteins that play a significant role in visual and auditory development. Encoded on the terminal exon of the teneurin genes is a family of bioactive peptides, termed teneurin C-terminal associated peptides (TCAP), which regulate mood-disorder associated behaviors. Thus, the teneurin-TCAP system could represent a novel neurological system underlying the origins of a number of complex neuropsychiatric conditions. However, it is not known if TCAP-1 exerts its effects as part of a direct teneurin function, whereby TCAP represents a functional region of the larger teneurin protein, or if it has an independent role, either as a splice variant or post-translational proteolytic cleavage product of teneurin. In this study, we show that TCAP-1 can be transcribed as a smaller mRNA transcript. After translation, further processing yields a smaller 15 kDa protein containing the TCAP-1 region. In the mouse hippocampus, immunoreactive (ir) TCAP-1 is exclusively localized to the pyramidal layers of the CA1, CA2 and CA3 regions. Although the localization of TCAP and teneurin in hippocampal regions is similar, they are distinct within the cell as most ir-teneurin is found at the plasma membrane, whereas ir-TCAP-1 is predominantly found in the cytosol. Moreover, in mouse embryonic hippocampal cell culture, FITC-labeled TCAP-1 binds to the plasma membrane and is taken up into the cytosol via dynamin-dependent caveolae-mediated endocytosis. Our data provides novel evidence that TCAP-1 is structurally and functionally distinct from the larger teneurins.

C-Terminal region of teneurin-1 co-localizes with dystroglycan and modulates cytoskeletal organization through an extracellular signal-regulated kinase-dependent stathmin- and filamin A-mediated mechanism in hippocampal cells

The pyramidal neurons in the hippocampus are extremely neuroplastic, and the complexity of dendritic branches can be dynamically altered in response to a variety of stimuli, including learning and stress. Recently, the teneurin family of proteins has emerged as an interneuronal and extracellular matrix signaling system that plays a significant role in brain development and neuronal communication. Encoded on the last exon of the teneurin genes is a new family of bioactive peptides termed the teneurin C-terminal-associated peptides (TCAPs). Previous studies indicate that TCAP-1 regulates axon fasciculation and dendritic morphology in the hippocampus. This study was aimed at understanding the molecular mechanisms by which TCAP-1 regulates these changes in the mouse hippocampus. Fluoresceinisothiocyanate (FITC)-labeled TCAP-1 binds to the pyramidal neurons of the CA2 and CA3, and dentate gyrus in the hippocampus of the mouse brain. Moreover, FITC-TCAP-1 co-localizes with β-dystroglycan upon binding to the plasma membrane of cultured immortalized mouse E14 hippocampal cells. In culture, TCAP-1 stimulates ERK1/2-dependent phosphorylation of the cytoskeletal regulatory proteins, stathmin at serine-25 and filamin A at serine-2152. In addition, TCAP-1 induces actin polymerization, increases immunoreactivity of tubulin-based cytoskeletal elements and causes a corresponding increase in filopodia formation and mean filopodia length in cultured hippocampal cells. We postulate that the TCAP-1 region of teneurin-1 has a direct action on the cytoskeletal reorganization that precedes neurite and process development in hippocampal neurons. Our data provides novel evidence that functionally links the teneurin and dystroglycan systems and provides new insight into the molecular mechanisms by which TCAP-1 regulates cytoskeletal dynamics in hippocampal neurons. The TCAP-dystroglycan system may represent a novel mechanism associated with the regulation of hippocampal-function.

Modulation of neuroplastic changes and corticotropin-releasing factor-associated behavior by a phylogenetically ancient and conserved peptide family

The co-evolution of peptides and early cells some 3.7 billion years ago provided bioactive peptides with a long history for the proliferation and refinement of peptide hormones. Central to the adaptation and evolution of cell types in metazoans is the development of peptide signaling systems that regulate stress mechanisms. The corticotropin-releasing factor (CRF) family of peptides represents the canonical family of peptides that are pivotal to the regulation of stress in vertebrates. However, these peptides appear to have evolved at least 2 billion years after the formation of the first postulated bioactive peptides, suggesting that before this, other peptide systems played a role in stress and energy metabolism. The teneurin C-terminal associated peptides (TCAPs) are a recently discovered family of highly conserved peptides that are processed from the teneurin transmembrane proteins. This peptide/protein system is ubiquitous in multicellular organisms and evolved before the CRF family. TCAP-1 is a potent regulator of CRF-associated physiology and behavior and may play a significant role in the regulation of cell-to-cell communication and neuroplasticity in neurons.

Teneurin C-terminal associated peptide (TCAP)-1 modulates dendritic morphology in hippocampal neurons and decreases anxiety-like behaviors in rats

Teneurin C-terminal associated peptide (TCAP)-1 is a member of a novel family of neuropeptides that has been highly conserved throughout evolution. TCAP-1 is expressed in the limbic system in areas such as the hippocampus and amygdala. In vitro, TCAP-1 increases cytoskeletal proteins in immortalized neurons and modulates neurite outgrowth in cultured primary hippocampal neurons. In vivo, TCAP-1 blocks stress-induced c-Fos in the hippocampus and amygdala, and modulates stress-induced anxiety-like behaviors. This suggests that TCAP-1 plays a role in the remodeling of limbic system networks to alter stress behaviors. Dendritic spines on the apical and basilar shafts of hippocampal neurons are sensitive to stress and many receive incoming excitatory synaptic connections. In this study, repeated daily injection of TCAP-1 for 10 days increased spine density in the CA1 and CA3 regions of the hippocampus without affecting spine density in the amygdala. Further investigation of the CA3 region indicated that TCAP-1 did not affect the morphology of apical dendrites, but decreased branching in the basilar dendrites 90-130 μm away from the soma. Moreover, TCAP-1 treatment increased open arm time and decreased closed arm entries on the elevated plus maze, a test of anxiety-like behavior. These results suggest that TCAP-1 may be associated with anxiety-like behavior via regulation of dendritic morphology in the hippocampus, independent of amygdalar modification.

The beta isotypes of tubulin in neuronal differentiation

The differences among the vertebrate beta isotypes of tubulin are highly conserved in evolution, suggesting that they have functional significance. To address this, we have used differentiating neuroblastoma cells as a model system. These cells express the betaI, betaII, and betaIII isotypes. Although there is no difference prior to differentiation, a striking difference is seen after differentiation. Both betaI and betaIII occur in cell bodies and neurites, while betaII occurs mostly in neurites. Knocking down betaI causes a large decrease in cell viability while silencing betaII and betaIII does not. Knocking down betaII causes a large decrease in neurite outgrowth without affecting viability. Knocking down betaIII has little effect on neurite outgrowth and only decreases viability if cells are treated with glutamate and glycine, a combination known to generate free radicals and reactive oxygen species. It appears, therefore, that betaI is required for cell viability, betaII for neurite outgrowth and betaIII for protection against free radicals and reactive oxygen species.

Behavioral effects of neuropeptides in rodent models of depression and anxiety

In recent years, studies have advocated neuropeptide systems as modulators for the behavioral states found in mood disorders such as depression and anxiety disorders. Neuropeptides have been tested in traditional animal models and screening procedures that have been validated by known antidepressants and anxiolytics. However, it has become clear that although these tests are very useful, neuropeptides have distinct behavioral effects and dose-dependent characteristics, and therefore, use of these tests with neuropeptides must be done with an understanding of their unique characteristics. This review will focus on the behavioral actions of neuropeptides and their synthetic analogs, particularly in studies utilizing various preclinical tests of depression and anxiety. Specifically, the following neuropeptide systems will be reviewed: corticotropin-releasing factor (CRF), urocortin (Ucn), teneurin C-terminal associated peptide (TCAP), neuropeptide Y (NPY), arginine vasopressin (AVP), oxytocin, the Tyr-MIF-1 family, cholecystokinin (CCK), galanin, and substance P. These neuropeptide systems each have a unique role in the regulation of stress-like behavior, and therefore provide intriguing therapeutic targets for mood disorder treatment.

Structural evolution of urotensin-I: reflections of life before corticotropin releasing factor

Peptides have a long evolutionary history that predates the appearance of metazoans. The corticotropin releasing factor (CRF) family of peptides is among the most ancient peptide lineages. The identification and characterization of urotensin-I and related orthologues led the way for the elucidation of the entire CRF peptide family. A comparative analysis of the CRF paralogue sequences suggest that CRF is the most derived of these peptides and has lost many of its ancestral characteristics after it became associated with the hypothalamic-pituitary-adrenal/interrenal (HPA/I axis). In vertebrates, the urotensin-I group of orthologues, which includes sauvagine and urocortin, possess a number of shared characteristics that may be indicative of the ancestral peptide. Given the early origin of the CRF family peptides, it is likely that other peptide lineages are distantly related to the CRF family. In silico or cDNA library screening using probes based on urotensin-I/urocortin characteristics have been used to identify novel CRF family and related sequences that provide clues the evolutionary origin of the CRF family.

Evolution of complementary peptide systems: teneurin C-terminal-associated peptides and corticotropin-releasing factor superfamilies

In chordates, the corticotropin-releasing factor (CRF) family of peptides consists of four paralogous lineages that include CRF, urocortin/urotensin-I, urocortin 2, and urocortin 3. Related to the CRF peptide family is the diuretic hormone family found in insects. This family consists of a number of paralogous lineages within the Insecta. The teneurin C-terminal-associated peptides (TCAP) are a recently described family of peptides with evolutionary origins around the same time as the CRF family. This family consists of four independent lineages in chordates that are orthologous to peptides in the Insecta. Like CRF, the peptides are 40 or 41 amino acids in length and share about 20% sequence identity to the CRF family members. Each of the four TCAP peptides is encoded by an exon that is closely associated with the teneurin gene. Recent studies indicate that TCAP can block CRF-mediated c-fos expression in the brain and modulate CRF-mediated behaviors. Thus, the TCAP family may act, in part, to modulate the physiological actions of the CRF family.

Teneurin-1 is expressed in interconnected regions of the developing brain and is processed in vivo

Background

Teneurins are a unique family of transmembrane proteins conserved from C. elegans and D. melanogaster to mammals. In vertebrates there are four paralogs (teneurin-1 to -4), all of which are expressed prominently in the developing central nervous system.

Results

Analysis of teneurin-1 expression in the developing chick brain by in situ hybridization and immunohistochemistry defined a unique, distinct expression pattern in interconnected regions of the brain. Moreover we found complementary patterns of teneurin-1 and-2 expression in many parts of the brain, including the retina, optic tectum, olfactory bulb, and cerebellum as well as in brain nuclei involved in processing of sensory information. Based on these expression patterns, we suspect a role for teneurins in neuronal connectivity.

In contrast to the cell-surface staining of the antibody against the extracellular domain, an antibody recognizing the intracellular domain revealed nuclear staining in subpopulations of neurons and in undifferentiated mesenchyme. Western blot analysis of brain lysates showed the presence of N-terminal fragments of teneurin-1 containing the intracellular domain indicating that proteolytic processing occurs. Finally, the teneurin-1 intracellular domain was found to contain a nuclear localization signal, which is required for nuclear localization in transfected cells.

Conclusion

Teneurin-1 and -2 are expressed by distinct interconnected populations of neurons in the developing central nervous system. Our data support the hypothesis that teneurins can be proteolytically processed leading to the release of the intracellular domain and its translocation to the nucleus.

Teneurin carboxy (C)-terminal associated peptide-1 inhibits alkalosis-associated necrotic neuronal death by stimulating superoxide dismutase and catalase activity in immortalized mouse hypothalamic cells

The teneurins and the teneurin C-terminal-associated peptides (TCAP) are implicated in the regulation of neuron growth and differentiation. However, current observations suggest that TCAP-1 may also have a neuroprotective action during times of pH-induced cellular stress in the brain such as during hypoxia-ischemia and brain alkalosis. To test this hypothesis, we cultured a TCAP-1-responsive mouse hypothalamic cell line, N38, using media buffered at pHs 6.8, 7.4, 8.0 and 8.4 subsequently treated with 100 nM TCAP-1. TCAP-1 significantly inhibited the decline in cell proliferation at pHs 8.0 and 8.4 as determined by direct cell viability assays and decreased the incidence of cells showing necrotic morphology. In addition, TCAP-1 decreased the number of cells undergoing necrosis by 4- to 5-fold as measured by uptake of ethidium homodimer III. Moreover, TCAP-1 significantly decreased the incidence of superoxide radicals and increased superoxide dismutase 1 (SOD1) expression. These results were accompanied by an increase in the SOD copper chaperone expression and increased catalase activity and expression. The results indicate that TCAP may play a neuroprotective role during periods of pH stress by upregulating oxygen radical scavenging systems. Thus, the TCAP-teneurin system may be part of a mechanism to protect neurons during trauma, such as hypoxia and ischemia.

Corticotropin-releasing factor (CRF)-induced behaviors are modulated by intravenous administration of teneurin C-terminal associated peptide-1 (TCAP-1)

The teneurin C-terminal associated peptides (TCAP) are a recently discovered family of bioactive peptides that can attenuate aspects of the behavioral stress responses of rats. Because TCAP has some structural similarity to the corticotropin-releasing factor (CRF) family of peptides, and modulates elements of the stress response, TCAP may act to modulate CRF actions in vivo. This hypothesis was tested by investigating anxiety-related behaviors in male rats following repeated intravenous (IV) TCAP-1 administration with either an acute intracerebroventricular (ICV) or IV CRF challenge. TCAP-1 alone did not affect behavioral responses significantly, however did significantly affect CRF-regulated behaviors depending on CRF's mode of injection. In both the elevated plus-maze and the open field tests, TCAP-1 had an anxiolytic effect on ICV CRF responses as indicated by decreased stretched-attend postures in the elevated plus maze (p<0.05), and increased center time and center entries in the open field (p<0.05). However, prior TCAP-1 treatment has an anxiogenic effect on the IV CRF-induced behaviors (decreased center entries and total distance in the open field (p<0.05)). TCAP-1's actions are not mediated through acute changes in glucocorticoid levels and may occur via a central action in the brain. A fluorescently (FITC)-labeled TCAP-1 analog was IV-administered to investigate whether IV TCAP-1 has the potential to regulate central mechanisms by crossing the blood-brain barrier. FITC-TCAP-1 was detected in blood vessels and fibers in the brain indicating that uptake into the brain is a possible route for its interaction with CRF and its receptors. Thus, TCAP may modulate CRF-associated behaviors by a direct action in the CNS.

Label-free detection of neuron–drug interactions using acoustic and Kelvin vibrational fields

Kelvin and acoustic fields of high-frequency have been employed in the non-invasive investigation of immortalized hypothalamic neurons, in order to assess their response to different concentrations of specific drugs, toxins, a stress-reducing hormone and neurotrophic factors. In an analytical systems biology approach, this work constitutes a first study of living neuron cultures by scanning Kelvin nanoprobe (SKN) and thickness shear mode (TSM) acoustic wave techniques. N-38 hypothalamic mouse neurons were immobilized on the gold electrode of 9 MHz TSM acoustic wave devices and gold-coated slides for study by SKN. The neurons were exposed to the neurochemicals betaseron, forskolin, TCAP, and cerebrolysin. Signals were collected with the TSM in real-time mode, and with the SKN in scanning and real-time modes, as the drugs were applied at biologically significant concentrations. With the TSM, for all drugs, some frequency and resistance shifts were in the same direction, contrary to normal functioning for this type of instrument. Possible mechanisms are presented to explain this behaviour. An oscillatory signal with periodicity of approximately 2 min was observed for some neuron-coated surfaces, where the amplitude of these oscillations was altered upon application of certain neurotrophic factors. These two new techniques present novel and non-invasive electrodeless methods for detecting changes at the cellular level caused by a variety of neuroactive compounds, without killing or destroying the neurons.