Control neuroendocrí de l'inici de la maduresa sexual en els vertebrats mitjançant la kisspeptina i el seu receptor, amb especial èmfasi pel que fa a la situació en els peixos teleostis

El recent descobriment de la kisspeptina (producte del gen KISS1), conjuntament amb el seu receptor (producte del gen KISS1R), i de la seva relació amb el control de l'inici de la maduresa sexual en tots els vertebrats, ha estat descrit com una de les troballes més rellevants de la biologia reproductiva en els últims anys. La kisspeptina té un efecte directe sobre l'hormona alliberadora de gonadotrofines, la qual desencadena una cascada hormonal que finalment acaba a les gònades amb la secreció dels esteroides sexuals, els quals provoquen la consegüent maduració de l'individu. En aquest treball s'explica el descobriment dels gens KISS1 i KISS1R, l'estructura d'aquests gens i dels seus productes proteics, i es fa referència als mecanismes endocrins responsables tant de la regulació endògena com dels possibles factors externs que afecten el sistema kisspeptina-KISS1R. També, i amb especial èmfasi en els peixos teleostis, es discuteixen les possibles causes de les diferències i similituds trobades en l'expressió cerebral del sistema kisspeptina-KISS1R. Finalment, s'avaluen les perspectives futures en el camp del control de la reproducció mitjançant la manipulació del sistema kisspeptina-KISS1R.The discovery of kisspeptin (the product of the KISS1 gene) together with its receptor (product of the KISS1R gene), and the relationship with the control of the onset of puberty in all vertebrates has been described as one the most important findings in reproductive biology in the last years. Kisspeptin stimulates gonadotrophin-releasing hormone (GnRH), initiating the hormonal cascade which ends in the gonads with the secretion of the sex steroids which, in turn, drive sexual maturation. This paper describes the origin and discovery of the KISS1 and KISS1R genes, the structure of these genes as well as their protein products. The endocrine mechanisms and the exogenous factors affecting the kisspeptin- KISS1R complex are also discussed. Finally, we describe the multiple functions in relationship with this system in all vertebrates and discuss the differences and similarities regarding the neural expression of kisspeptin-KISS1R complex in several teleost fishes. Finally, the future perspectives in the field of the control reproduction by the manipulation of the kisspeptin-KISS1R complex are discussed

Morphology and Nanomechanics of Sensory Neurons Growth Cones following Peripheral Nerve Injury

A prior peripheral nerve injury in vivo, promotes a rapid elongated mode of sensory neurons neurite regrowth in vitro. This in vitro model of conditioned axotomy allows analysis of the cellular and molecular mechanisms leading to an improved neurite re-growth. Our differential interference contrast microscopy and immunocytochemistry results show that conditioned axotomy, induced by sciatic nerve injury, did not increase somatic size of adult lumbar sensory neurons from mice dorsal root ganglia sensory neurons but promoted the appearance of larger neurites and growth cones. Using atomic force microscopy on live neurons, we investigated whether membrane mechanical properties of growth cones of axotomized neurons were modified following sciatic nerve injury. Our data revealed that neurons having a regenerative growth were characterized by softer growth cones, compared to control neurons. The increase of the growth cone membrane elasticity suggests a modification in the ratio and the inner framework of the main structural proteins

Regulation of the Na,K-ATPase Gamma-Subunit FXYD2 by Runx1 and Ret Signaling in Normal and Injured Non-Peptidergic Nociceptive Sensory Neurons

Dorsal root ganglia (DRGs) contain the cell bodies of sensory neurons which relay nociceptive, thermoceptive, mechanoceptive and proprioceptive information from peripheral tissues toward the central nervous system. These neurons establish constant communication with their targets which insures correct maturation and functioning of the somato-sensory nervous system. Interfering with this two-way communication leads to cellular, electrophysiological and molecular modifications that can eventually cause neuropathic conditions. In this study we reveal that FXYD2, which encodes the gamma-subunit of the Na,K-ATPase reported so far to be mainly expressed in the kidney, is induced in the mouse DRGs at postnatal stages where it is restricted specifically to the TrkB-expressing mechanoceptive and Ret-positive/IB4-binding non-peptidergic nociceptive neurons. In non-peptidergic nociceptors, we show that the transcription factor Runx1 controls FXYD2 expression during the maturation of the somato-sensory system, partly through regulation of the tyrosine kinase receptor Ret. Moreover, Ret signaling maintains FXYD2 expression in adults as demonstrated by the axotomy-induced down-regulation of the gene that can be reverted by in vivo delivery of GDNF family ligands. Altogether, these results establish FXYD2 as a specific marker of defined sensory neuron subtypes and a new target of the Ret signaling pathway during normal maturation of the non-peptidergic nociceptive neurons and after sciatic nerve injury

Differential transcriptional profiling of damaged and intact adjacent dorsal root ganglia neurons in neuropathic pain

Neuropathic pain, caused by a lesion in the somatosensory system, is a severely impairing mostly chronic disease. While its underlying molecular mechanisms are not thoroughly understood, neuroimmune interactions as well as changes in the pain pathway such as sensitization of nociceptors have been implicated. It has been shown that not only are different cell types involved in generation and maintenance of neuropathic pain, like neurons, immune and glial cells, but, also, intact adjacent neurons are relevant to the process. Here, we describe an experimental approach to discriminate damaged from intact adjacent neurons in the same dorsal root ganglion (DRG) using differential fluorescent neuronal labelling and fluorescence-activated cell sorting (FACS). Two fluorescent tracers, Fluoroemerald (FE) and 1-dioctadecyl-3,3,3,3-tetramethylindocarbocyanine perchlorate (DiI), were used, whose properties allow us to distinguish between damaged and intact neurons. Subsequent sorting permitted transcriptional analysis of both groups. Results and qPCR validation show a strong regulation in damaged neurons versus contralateral controls as well as a moderate regulation in adjacent neurons. Data for damaged neurons reveal an mRNA expression pattern consistent with established upregulated genes like galanin, which supports our approach. Moreover, novel genes were found strongly regulated such as corticotropinreleasing hormone (CRH), providing novel targets for further research. Differential fluorescent neuronal labelling and sorting allows for a clear distinction between primarily damaged neuropathic neurons and "bystanders," thereby facilitating a more detailed understanding of their respective roles in neuropathic processes in the DRG

Clustering-based approaches to SAGE data mining

Serial analysis of gene expression (SAGE) is one of the most powerful tools for global gene expression profiling. It has led to several biological discoveries and biomedical applications, such as the prediction of new gene functions and the identification of biomarkers in human cancer research. Clustering techniques have become fundamental approaches in these applications. This paper reviews relevant clustering techniques specifically designed for this type of data. It places an emphasis on current limitations and opportunities in this area for supporting biologically-meaningful data mining and visualisation

Fast- or Slow-inactivated State Preference of Na+ Channel Inhibitors: A Simulation and Experimental Study

Sodium channels are one of the most intensively studied drug targets. Sodium channel inhibitors (e.g., local anesthetics, anticonvulsants, antiarrhythmics and analgesics) exert their effect by stabilizing an inactivated conformation of the channels. Besides the fast-inactivated conformation, sodium channels have several distinct slow-inactivated conformational states. Stabilization of a slow-inactivated state has been proposed to be advantageous for certain therapeutic applications. Special voltage protocols are used to evoke slow inactivation of sodium channels. It is assumed that efficacy of a drug in these protocols indicates slow-inactivated state preference. We tested this assumption in simulations using four prototypical drug inhibitory mechanisms (fast or slow-inactivated state preference, with either fast or slow binding kinetics) and a kinetic model for sodium channels. Unexpectedly, we found that efficacy in these protocols (e.g., a shift of the “steady-state slow inactivation curve”), was not a reliable indicator of slow-inactivated state preference. Slowly associating fast-inactivated state-preferring drugs were indistinguishable from slow-inactivated state-preferring drugs. On the other hand, fast- and slow-inactivated state-preferring drugs tended to preferentially affect onset and recovery, respectively. The robustness of these observations was verified: i) by performing a Monte Carlo study on the effects of randomly modifying model parameters, ii) by testing the same drugs in a fundamentally different model and iii) by an analysis of the effect of systematically changing drug-specific parameters. In patch clamp electrophysiology experiments we tested five sodium channel inhibitor drugs on native sodium channels of cultured hippocampal neurons. For lidocaine, phenytoin and carbamazepine our data indicate a preference for the fast-inactivated state, while the results for fluoxetine and desipramine are inconclusive. We suggest that conclusions based on voltage protocols that are used to detect slow-inactivated state preference are unreliable and should be re-evaluated

New Insights in the Contribution of Voltage-Gated Nav Channels to Rat Aorta Contraction

BACKGROUND: Despite increasing evidence for the presence of voltage-gated Na(+) channels (Na(v)) isoforms and measurements of Na(v) channel currents with the patch-clamp technique in arterial myocytes, no information is available to date as to whether or not Na(v) channels play a functional role in arteries. The aim of the present work was to look for a physiological role of Na(v) channels in the control of rat aortic contraction. METHODOLOGY/PRINCIPAL FINDINGS: Na(v) channels were detected in the aortic media by Western blot analysis and double immunofluorescence labeling for Na(v) channels and smooth muscle alpha-actin using specific antibodies. In parallel, using real time RT-PCR, we identified three Na(v) transcripts: Na(v)1.2, Na(v)1.3, and Na(v)1.5. Only the Na(v)1.2 isoform was found in the intact media and in freshly isolated myocytes excluding contamination by other cell types. Using the specific Na(v) channel agonist veratridine and antagonist tetrodotoxin (TTX), we unmasked a contribution of these channels in the response to the depolarizing agent KCl on rat aortic isometric tension recorded from endothelium-denuded aortic rings. Experimental conditions excluded a contribution of Na(v) channels from the perivascular sympathetic nerve terminals. Addition of low concentrations of KCl (2-10 mM), which induced moderate membrane depolarization (e.g., from -55.9+/-1.4 mV to -45.9+/-1.2 mV at 10 mmol/L as measured with microelectrodes), triggered a contraction potentiated by veratridine (100 microM) and blocked by TTX (1 microM). KB-R7943, an inhibitor of the reverse mode of the Na(+)/Ca(2+) exchanger, mimicked the effect of TTX and had no additive effect in presence of TTX. CONCLUSIONS/SIGNIFICANCE: These results define a new role for Na(v) channels in arterial physiology, and suggest that the TTX-sensitive Na(v)1.2 isoform, together with the Na(+)/Ca(2+) exchanger, contributes to the contractile response of aortic myocytes at physiological range of membrane depolarization

Oligomeric states in sodium ion-dependent regulation of cyanobacterial histidine kinase-2

IMI thanks Queen Mary University of London for a graduate teaching studentship. LW thanks the China Scholarship Council (CSC) and Queen Mary University of London for financial support. SP held a Leverhulme Trust early-career post-doctoral research fellowship. JN is grateful for the continued support of the JST CREST Grant Number JPMJCR13M4, Japan. JFA acknowledges the support of research grant F/07 476/AQ and fellowship EM-2015-068 of the Leverhulme Trust

Control neuroendocrí de l'inici de la maduresa sexual en els vertebrats mitjançant la kisspeptina i el seu receptor, amb especial èmfasi pel que fa a la situació en els peixos teleostis

El recent descobriment de la kisspeptina (producte del gen KISS1), conjuntament amb el seu receptor (producte del gen KISS1R), i de la seva relació amb el control de l'inici de la maduresa sexual en tots els vertebrats, ha estat descrit com una de les troballes més rellevants de la biologia reproductiva en els últims anys. La kisspeptina té un efecte directe sobre l'hormona alliberadora de gonadotrofines, la qual desencadena una cascada hormonal que finalment acaba a les gònades amb la secreció dels esteroides sexuals, els quals provoquen la consegüent maduració de l'individu. En aquest treball s'explica el descobriment dels gens KISS1 i KISS1R, l'estructura d'aquests gens i dels seus productes proteics, i es fa referència als mecanismes endocrins responsables tant de la regulació endògena com dels possibles factors externs que afecten el sistema kisspeptina-KISS1R. També, i amb especial èmfasi en els peixos teleostis, es discuteixen les possibles causes de les diferències i similituds trobades en l'expressió cerebral del sistema kisspeptina-KISS1R. Finalment, s'avaluen les perspectives futures en el camp del control de la reproducció mitjançant la manipulació del sistema kisspeptina-KISS1R.The discovery of kisspeptin (the product of the KISS1 gene) together with its receptor (product of the KISS1R gene), and the relationship with the control of the onset of puberty in all vertebrates has been described as one the most important findings in reproductive biology in the last years. Kisspeptin stimulates gonadotrophin-releasing hormone (GnRH), initiating the hormonal cascade which ends in the gonads with the secretion of the sex steroids which, in turn, drive sexual maturation. This paper describes the origin and discovery of the KISS1 and KISS1R genes, the structure of these genes as well as their protein products. The endocrine mechanisms and the exogenous factors affecting the kisspeptin- KISS1R complex are also discussed. Finally, we describe the multiple functions in relationship with this system in all vertebrates and discuss the differences and similarities regarding the neural expression of kisspeptin-KISS1R complex in several teleost fishes. Finally, the future perspectives in the field of the control reproduction by the manipulation of the kisspeptin-KISS1R complex are discussed