Cav1.4 calcium channels control cytokine production by human peripheral TH17 cells and psoriatic skin-infiltrating T cells.

BACKGROUND: Type-17 inflammation characterizes psoriasis, a chronic skin disease. Because several inflammatory cytokines contribute to psoriasis pathogenesis, inhibiting the simultaneous production of these cytokines in TH17 cells may be beneficial in psoriasis. We found that Cav1.4, encoded by CACNA1F, was the only Cav1 calcium channel expressed in TH17 cells. OBJECTIVE: We sought to investigate the role of Cav1.4 expression in early TH17-activation events and effector functions, as well as its association with TH17 signature genes in lesional psoriatic (LP) skins. METHODS: Transcriptional gene signatures associated with CACNA1F expression were examined in LP skins by RT-PCR and in situ hybridization. Cav1 inhibitor and/or shRNA lentivectors were used to assess the contribution of Cav1.4 in TH17 activation and effector functions in a 3-dimensional skin reconstruction model. RESULTS: CACNA1F expression correlated with inflammatory cytokine expression that characterizes LP skins and was preferentially associated with RORC expression in CD4+ and CD4- cells from LP biopsies. Nicardipine, a Cav1 channel antagonist, markedly reduced inflammatory cytokine production by TH17 cells from blood or LP skin. This was associated with decreased TCR-induced early calcium events at cell membrane and proximal signaling events. The knockdown of Cav1.4 in TH17 cells impaired cytokine production. Finally, Cav1 inhibition reduced the expression of the keratinocyte genes characteristic of TH17-mediated psoriasis inflammation in human skin equivalents. CONCLUSIONS: Cav1.4 channels promote TH17-cell functions both at the periphery and in inflammatory psoriatic skin.

Separation of the CaV 1.2-CaV 1.3 calcium channel duo prevents type 2 allergic airway inflammation.

BACKGROUND: Voltage-gated calcium (Cav 1) channels contribute to T-lymphocyte activation. Cav 1.2 and Cav 1.3 channels are expressed in Th2 cells but their respective roles are unknown, which is investigated herein. METHODS: We generated mice deleted for Cav 1.2 in T cells or Cav 1.3 and analyzed TCR-driven signaling. In this line, we developed original fast calcium imaging to measure early elementary calcium events (ECE). We also tested the impact of Cav 1.2 or Cav 1.3 deletion in models of type 2 airway inflammation. Finally, we checked whether the expression of both Cav 1.2 and Cav 1.3 in T cells from asthmatic children correlates with Th2-cytokine expression. RESULTS: We demonstrated non-redundant and synergistic functions of Cav 1.2 and Cav 1.3 in Th2 cells. Indeed, the deficiency of only one channel in Th2 cells triggers TCR-driven hyporesponsiveness with weakened tyrosine phosphorylation profile, a strong decrease in initial ECE and subsequent reduction in the global calcium response. Moreover, Cav 1.3 has a particular role in calcium homeostasis. In accordance with the singular roles of Cav 1.2 and Cav 1.3 in Th2 cells, deficiency in either one of these channels was sufficient to inhibit cardinal features of type 2 airway inflammation. Furthermore, Cav 1.2 and Cav 1.3 must be co-expressed within the same CD4+ T cell to trigger allergic airway inflammation. Accordingly with the concerted roles of Cav 1.2 and Cav 1.3, the expression of both channels by activated CD4+ T cells from asthmatic children was associated with increased Th2-cytokine transcription. CONCLUSIONS: Thus, Cav 1.2 and Cav 1.3 act as a duo, and targeting only one of these channels would be efficient in allergy treatment.

Transmembrane H+ fluxes and the regulation of neural induction in Xenopus laevis.

It has previously been reported that in ex vivo planar explants prepared from Xenopus laevis embryos, the intracellular pH (pHi) increases in cells of the dorsal ectoderm from stage 10.5 to 11.5 (i.e. 11-12.5 hpf). It was proposed that such increases (potentially due to H+ being extruded, sequestered, or buffered in some manner), play a role in regulating neural induction. Here, we used an extracellular ion-selective electrode to non-invasively measure H+ fluxes at eight locations around the equatorial circumference of intact X. laevis embryos between stages 9-12 (˜7-13.25 hpf). We showed that at stages 9-11, there was a small H+ efflux recorded from all the measuring positions. At stage 12 there was a small, but significant, increase in the efflux of H+ from most locations, but the efflux from the dorsal side of the embryo was significantly greater than from the other positions. Embryos were also treated from stages 9-12 with bafilomycin A1, to block the activity of the ATP-driven H+ pump. By stage 22 (24 hpf), these embryos displayed retarded development, arresting before the end of gastrulation and therefore did not display the usual anterior and neural structures, which were observed in the solvent-control embryos. In addition, expression of the early neural gene, Zic3, was absent in treated embryos compared with the solvent controls. Together, our new in vivo data corroborated and extended the earlier explant-derived report describing changes in pHi that were suggested to play a role during neural induction in X. laevis embryos.

Reliability of measurements of a reflection coefficient index to indicate spinal bone strength on adolescents with idiopathic scoliosis (AIS): a pilot study.

PURPOSE: To investigate the test-retest, intra- and inter-rater reliabilities of an ultrasound (US) reflection coefficient (RC) index measured in a lumbar vertebra to reflect bone strength on children with AIS. METHODS: Fifty-eight participants (47F; 11M) were scanned by an US imager in standing position. Twenty-four were scanned twice for a test-retest study. The RC index measures the US signal reflected from L5 to indicate bone strength. Five measurements were obtained using three different methods: (i) the maximum RC (MRC) values on the left and right sides, (ii) the average RC (ARC) values on left and right sides, and (iii) the combined average RC (CARC) from both sides. Only rater 1 measured the 24 repeated US scans once. Raters 1 and 2 measured the RC index twice on all 58 images in 1 week apart. The intraclass correlation coefficient ICC [3, 1] for test-retest and ICC [2, 1] for intra- and inter-rater reliabilities as well as the standard error of measurements (SEM) were reported. RESULTS: The means of scan 1 versus scan 2 were 0.16 ± 0.08 versus 0.16 ± 0.07 for left-MRC, 0.17 ± 0.11 versus 0.18 ± 0.11 for right-MRC, 0.08 ± 0.04 versus 0.09 ± 0.04 for left-ARC, 0.09 ± 0.04 versus 0.09 ± 0.05 for right-ARC and 0.08 ± 0.04 versus 0.09 ± 0.03 for CARC and all ICC[3, 1] ≥ 0.77. Among these 5 approaches, the CARC provided the best intra-rater and inter-rater reliabilities with ICC [2, 1] ≥ 0.84 and SEM ≤ 0.01. CONCLUSIONS: The RC index could be measured repeatably and reliably. The high RC value may reduce the risk of progression of scoliosis.

Patients with adolescent idiopathic scoliosis perceive positive improvements regardless of change in the Cobb angle - Results from a randomized controlled trial comparing a 6-month Schroth intervention added to standard care and standard care alone. SOSORT 2018 Award winner.

BACKGROUND: The Cobb angle is proposed as the "disease process" outcome for scoliosis research because therapies aim to correct or stop curve progression. While the Scoliosis Research Society recommends the Cobb angle as the primary outcome, the Society on Scoliosis Orthopaedic and Rehabilitation Treatment prioritises, as a general goal, patient related outcomes over Cobb angle progression. OBJECTIVE: To determine the threshold of change in the Cobb angle in adolescents with idiopathic scoliosis (AIS) who perceive improvement in a 6-months randomized controlled trial comparing a Schroth exercise intervention added to the standard of care to the standard of care alone. METHODS: This is a secondary analysis of data from a randomized controlled trial of 50 patients with AIS, with curves ranging from 10° to 45°, with or without a brace. Participants with diagnoses other than AIS, surgical candidates or patients who had scoliosis surgery were excluded. The 6-month interventions consisted of Schroth exercises added to standard-of-care (observation or bracing) with daily home exercises and weekly therapy sessions (Schroth) or standard-of-care alone (Control). The anchor method for estimating the minimal important difference (MID) in the largest Cobb angles (LC) was used. Patient-reported change in back status over the 6-month treatment period was measured using the Global Rating of Change (GRC) scale as anchor varying from - 7 ("great deal worse") to + 7 ("great deal better"). Participants were divided into two groups based on GRC scores: Improved (GRC ≥2) or Stable/Not Improved (GRC ≤1). MID was defined as the change in the LC that most accurately predicted the GRC classification as per the receiver operating characteristic curve (ROC). RESULTS: The average age was 13.4 ± 1.6 years and the average LC was 28.5 ± 8.8 °s. The average GRC in the control group was - 0.1 ± 1.6, compared to + 4.4 ± 2.2 in the Schroth group. The correlation between LC and GRC was adequate (r = - 0.34, p < 0.05). The MID for the LC was 1.0 °. The area under the ROC was 0.69 (0.52-0.86), suggesting a 70% chance to properly classify a patient as perceiving No Improvement/Stable or Improvement based on the change in the LC. CONCLUSION: Patients undergoing Schroth treatment perceived improved status of their backs even if the Cobb angle did not improve beyond the conventionally accepted threshold of 5°. Standard of care aims to slow/stop progression while Schroth exercises aim to improve postural balance, signs and symptoms of scoliosis. Given the very small MID, perceived improvement in back status is likely due to something other than the Cobb angle. This study warrants investigating alternatives to the Cobb angle that might be more relevant to patients. TRIAL REGISTRATION: ClinicalTrials.gov , NCT01610908 . Retrospectively registered on April 2, 2012 (first posted on June 4, 2012 - https://clinicaltrials.gov/ct2/keydates/NCT01610908 ).

Bisacodyl and its cytotoxic activity on human glioblastoma stem-like cells. Implication of inositol 1,4,5-triphosphate receptor dependent calcium signaling.

Glioblastoma is the most common malignant brain tumor. The heterogeneity at the cellular level, metabolic specificities and plasticity of the cancer cells are a challenge for glioblastoma treatment. Identification of cancer cells endowed with stem properties and able to propagate the tumor in animal xenografts has opened a new paradigm in cancer therapy. Thus, to increase efficacy and avoid tumor recurrence, therapies need to target not only the differentiated cells of the tumor mass, but also the cancer stem-like cells. These therapies need to be effective on cells present in the hypoxic, slightly acidic microenvironment found within tumors. Such a microenvironment is known to favor more aggressive undifferentiated phenotypes and a slow-growing "quiescent state" that preserves the cells from chemotherapeutic agents, which mostly target proliferating cells. Based on these considerations, we performed a differential screening of the Prestwick Chemical Library of approved drugs on both proliferating and quiescent glioblastoma stem-like cells and identified bisacodyl as a cytotoxic agent with selectivity for quiescent glioblastoma stem-like cells. In the present study we further characterize bisacodyl activity and show its efficacy in vitro on clonal macro-tumorospheres, as well as in vivo in glioblastoma mouse models. Our work further suggests that bisacodyl acts through inhibition of Ca2+ release from the InsP3 receptors.

Assessment of curve progression on children with idiopathic scoliosis using ultrasound imaging method.

PURPOSE: To investigate the threshold of the curve difference on ultrasound measurement relative to the previous radiographic measurements to detect curves progression in children who have idiopathic scoliosis (IS). METHODS: Two hundred children with IS (F:170, M:30; mean age: 14.6 ± 1.9) were recruited from a single center. A retrospective study on comparing the current ultrasound measurements with the previous radiographic measurements with threshold values from 3° to 8° to detect curve progression was conducted. The receiver operating characteristic (ROC) analysis, accuracy (ACC), and odd ratio (OR) were calculated to determine the optimal threshold value of the curve differences between ultrasound and previous radiographic measurement. RESULTS: Both thresholds of 4° and 5° for curve difference from ultrasound scans presented the sensitivities ≥ 0.90 and specificities ≥ 0.85, and can reduce by 73 and 79% of radiographs on the studied subjects, respectively. Especially, for 4° threshold, the negative likelihood ratio (LR-) was only 0.08, which indicated that there is only 8% probability that the subject has progressed if the US measurement detected non-progression. CONCLUSIONS: The ultrasound imaging method can be applied to identify curve progression in children with IS. Four degree is the preferred threshold value to detect the curve which had progressed, since it also had the lower rate of undetected progressed cases (false negatives).

Calcium signaling orchestrates glioblastoma development: Facts and conjunctures.

While it is a relatively rare disease, glioblastoma multiform (GBM) is one of the more deadly adult cancers. Following current interventions, the tumor is never eliminated whatever the treatment performed; whether it is radiotherapy, chemotherapy, or surgery. One hypothesis to explain this poor outcome is the "cancer stem cell" hypothesis. This concept proposes that a minority of cells within the tumor mass share many of the properties of adult neural stem cells and it is these that are responsible for the growth of the tumor and its resistance to existing therapies. Accumulating evidence suggests that Ca(2+) might also be an important positive regulator of tumorigenesis in GBM, in processes involving quiescence, maintenance, proliferation, or migration. Glioblastoma tumors are generally thought to develop by co-opting pathways that are involved in the formation of an organ. We propose that the cells initiating the tumor, and subsequently the cells of the tumor mass, must hijack the different checkpoints that evolution has selected in order to prevent the pathological development of an organ. In this article, two main points are discussed. (i) The first is the establishment of a so-called "cellular society," which is required to create a favorable microenvironment. (ii) The second is that GBM can be considered to be an organism, which fights to survive and develop. Since GBM evolves in a limited space, its only chance of development is to overcome the evolutionary checkpoints. For example, the deregulation of the normal Ca(2+) signaling elements contributes to the progression of the disease. Thus, by manipulating the Ca(2+) signaling, the GBM cells might not be killed, but might be reprogrammed toward a new fate that is either easy to cure or that has no aberrant functioning. This article is part of a Special Issue entitled: Calcium and Cell Fate. Guest Editors: Jacques Haiech, Claus Heizmann, Joachim Krebs, Thierry Capiod and Olivier Mignen.

TRPP2-dependent Ca2+ signaling in dorso-lateral mesoderm is required for kidney field establishment in Xenopus.

In Xenopus laevis embryos, kidney field specification is dependent on retinoic acid (RA) and coincides with a dramatic increase of Ca(2+) transients, but the role of Ca(2+) signaling in the kidney field is unknown. Here, we identify TRPP2, a member of the transient receptor potential (TRP) superfamily of channel proteins encoded by the pkd2 gene, as a central component of Ca(2+) signaling in the kidney field. TRPP2 is strongly expressed at the plasma membrane where it might regulate extracellular Ca(2+) entry. Knockdown of pkd2 in the kidney field results in the downregulation of pax8, but not of other kidney field genes (lhx1, osr1 and osr2). We further show that inhibition of Ca(2+) signaling with an inducible Ca(2+) chelator also causes downregulation of pax8, and that pkd2 knockdown results in a severe inhibition of Ca(2+) transients in kidney field explants. Finally, we show that disruption of RA results both in an inhibition of intracellular Ca(2+) signaling and of TRPP2 incorporation into the plasma membrane of kidney field cells. We propose that TRPP2-dependent Ca(2+) signaling is a key component of pax8 regulation in the kidney field downstream of RA-mediated non-transcriptional control of TRPP2.

Kcnip1 a Ca²âº-dependent transcriptional repressor regulates the size of the neural plate in Xenopus.

In amphibian embryos, our previous work has demonstrated that calcium transients occurring in the dorsal ectoderm at the onset of gastrulation are necessary and sufficient to engage the ectodermal cells into a neural fate by inducing neural specific genes. Some of these genes are direct targets of calcium. Here we search for a direct transcriptional mechanism by which calcium signals are acting. The only known mechanism responsible for a direct action of calcium on gene transcription involves an EF-hand Ca²âº binding protein which belongs to a group of four proteins (Kcnip1 to 4). Kcnip protein can act in a Ca²âº-dependent manner as a transcriptional repressor by binding to a specific DNA sequence, the Downstream Regulatory Element (DRE) site. In Xenopus, among the four kcnips, we show that only kcnip1 is timely and spatially present in the presumptive neural territories and is able to bind DRE sites in a Ca²âº-dependent manner. The loss of function of kcnip1 results in the expansion of the neural plate through an increased proliferation of neural progenitors. Later on, this leads to an impairment in the development of anterior neural structures. We propose that, in the embryo, at the onset of neurogenesis Kcnip1 is the Ca²âº-dependent transcriptional repressor that controls the size of the neural plate. This article is part of a Special Issue entitled: 13th European Symposium on Calcium.

CRN13 candidate effectors from plant and animal eukaryotic pathogens are DNA-binding proteins which trigger host DNA damage response.

To successfully colonize their host, pathogens produce effectors that can interfere with host cellular processes. Here we investigated the function of CRN13 candidate effectors produced by plant pathogenic oomycetes and detected in the genome of the amphibian pathogenic chytrid fungus Batrachochytrium dendrobatidis (BdCRN13). When expressed in Nicotiana, AeCRN13, from the legume root pathogen Aphanomyces euteiches, increases the susceptibility of the leaves to the oomycete Phytophthora capsici. When transiently expressed in amphibians or plant cells, AeCRN13 and BdCRN13 localize to the cell nuclei, triggering aberrant cell development and eventually causing cell death. Using Förster resonance energy transfer experiments in plant cells, we showed that both CRN13s interact with nuclear DNA and trigger plant DNA damage response (DDR). Mutating key amino acid residues in a predicted HNH-like endonuclease motif abolished the interaction of AeCRN13 with DNA, the induction of DDR and the enhancement of Nicotiana susceptibility to P. capsici. Finally, H2AX phosphorylation, a marker of DNA damage, and enhanced expression of genes involved in the DDR were observed in A. euteiches-infected Medicago truncatula roots. These results show that CRN13 from plant and animal eukaryotic pathogens promotes host susceptibility by targeting nuclear DNA and inducing DDR.

How quantity and quality of brace wear affect the brace treatment outcomes for AIS.

PURPOSE: To determine the reliability of a prognostic curve progression model and the role of the quantity and quality of brace wear for adolescent idiopathic scoliosis (AIS) brace treatment. METHODS: To develop a curve progression model for full-time AIS brace treatment, 20 AIS subjects (Group 1) prescribed full-time thoracolumbar sacral orthosis (TLSO) were monitored and followed for 2 years beyond maturity. The developed curve progression model was: curve progression (in degrees) = 33 + 0.11 × Peterson risk (%) - 0.07 in-brace correction (%) - 0.45 × quality (%) - 0.48 × quantity (%) + 0.0062 × quantity × quality. To validate the model, 40 new (test) subjects (Group 2) who met the same inclusion criteria and used the same type of monitors, were monitored and followed for 2 years after bracing. RESULTS: For the 40 test subjects (Group 2), the average in-brace correction was 40 ± 22 %. The average quantity and quality of the brace wear were 56 ± 19 and 55 ± 17 %, respectively. Twelve subjects (30 %) progressed of which 10 subjects (25 %) required surgery and 28 subjects (70 %) showed no progression. The accuracy of the model to determine which patients would progress was 88 % (35/40) which was better than the Peterson's risk model (68 %; 26/40) alone. Patients who had the combined quantity times the quality over a threshold 43 % had a success treatment rate of 95 %. CONCLUSIONS: This study showed the prognostic model of brace treatment outcome on AIS patients treated with full-time TLSO was reliable. Both the quantity and quality of the brace wear were important factors in achieving successful brace treatment.

Hspa9 is required for pronephros specification and formation in Xenopus laevis.

BACKGROUND: Development of the pronephros in Xenopus laevis is largely dependent on retinoic acid signaling at the time of kidney field specification with the simultaneous occurrence of a necessary calcium signaling. At the crossroads of these two signaling pathways, we studied the role of Hspa9 (heat shock 70 kDa protein 9) encoding a mitochondrial chaperone in pronephros development. RESULTS: We first showed that Hspa9 is highly expressed in the pronephros territory and elongating nephric duct. We then observed that upon reduced retinoic acid signaling hspa9 expression was reduced as pax8 and pax2. Overexpression of hspa9 enlarged the pax8 positive pronephros territory, leading to a larger pronephric tubule. Loss of function of hspa9 in the kidney field using morpholino approach severely reduced pax8 expression and pronephros formation. Phenotypic rescue was achieved by co-injection of the full-length murine Hspa9 mRNA. However, no rescue was observed when Hspa9 mRNA lacking the mitochondrial-targeting sequence was injected, as this truncated form is able to interfere with pronephros formation when injected solely. CONCLUSIONS: Hspa9 is an important mediator for pronephros development through modulation of pax8. Mitochondrial functions of hspa9 are likely to be involved in specification of pronephric cell fate.

Smart brace versus standard rigid brace for the treatment of scoliosis: a pilot study.

The outcomes of brace treatment for scoliosis depend on how the brace is used. Simply prescribing a brace does not mean it will be worn properly. A smart brace has been developed to control the brace wear tightness with the expectation that appropriately worn braces will improve outcomes. Twelve brace candidates (10F; 2M) agreed to participate into this study and were randomly divided into 2 groups. The smart brace group used the smart brace for the first year, and then wore the standard brace for the following year. The standard rigid brace group wore their TLSO for 2 years. Both groups were followed for 3 years after they finished the brace treatment. The smart brace group showed better quality of brace wear, wearing their brace at the prescribed tightness level a higher proportion of time than the standard brace group. All subjects in the smart brace group had successful outcomes, Cobb angle changed less than 5°, whereas 2/6 subjects in the standard brace group had unsuccessful bracing. One had 7° increment and 1 underwent surgery. The smart brace group also reported that the smart brace was more comfortable to wear than the standard rigid brace.

Brace wear characteristics during the first 6 months for the treatment of scoliosis.

Bracing is the most commonly used non-surgical treatment for adolescent idiopathic scoliosis (AIS) and requires an extensive commitment on the part of the patient and family. However, demonstrating efficacy of brace treatment for AIS has been hampered by the lack of compressive information about wear characteristics. The first 6 months is considered a critical time to evaluate whether AIS patients will commit to the treatment and may predict the treatment outcome. The characteristics of brace wear can assist clinicians to provide better support and aid long term compliance with treatment. This study describes the first 6 month brace wear characteristics in 15 AIS patients (12F;3M) who were prescribed full-time brace wear. There was a statistically significant increase in wear time (p = 0.02) after brace fitting and the brace wear tightness stabilized after month 4. The force at the major pressure pad area continuously decreased after month 2. A moderate correlation was found between the (quantity * quality) of the brace wear at month 6 and the change of Cobb angle (first out of brace - pre brace) (r2 = 0.47). The more time that the brace was worn and the higher proportion of time worn at the prescribed tightness or above improves the likelihood of a better treatment result.

Knocking down Cav1 calcium channels implicated in Th2 cell activation prevents experimental asthma.

RATIONALE: Th2 cells orchestrate allergic asthma and the cytokines they produce (IL-4, IL-5, and IL-13) are deleterious in allergy. Therefore, it is important to identify key signaling molecules expressed by Th2 cells that are essential for their function. We have previously shown that dihydropyridines selectively modulate Th2 cell functions. OBJECTIVES: Because dihydropyridines bind to and modulate voltage-dependent calcium (Ca(v)1) channel in excitable cells, we aimed at showing that Th2 cells selectively express functional Ca(v)1-related channels, the inhibition of which may prevent asthma. METHODS: We looked for Ca(v)1 channel expression in Th2 and Th1 cells by real-time polymerase chain reaction and Western blotting. We sequenced the isoforms expressed by Th2 cells and tested whether Ca(v)1 antisense oligodeoxynucleotides (Ca(v)1AS) affected Ca(2+) signaling and cytokine production. Finally, we tested the effect of Ca(v)1AS in the passive asthma model by injection of ovalbumin-specific Th2 cells transfected with Ca(v)1AS into BALB/c mice challenged with intranasal ovalbumin and in the active model of asthma by intranasal delivery of Ca(v)1AS together with soluble ovalbumin in BALB/c mice previously immunized with ovalbumin in alum. MEASUREMENTS AND MAIN RESULTS: We show that mouse Th2 but not Th1 cells expressed Ca(v)1.2 and Ca(v)1.3 channels. Th2 cells transfected with Ca(v)1AS had impaired Ca(2+) signaling and cytokine production, and lost their ability to induce airway inflammation on adoptive transfer. Furthermore, intranasal administration of Ca(v)1AS suppressed airway inflammation and hyperreactivity in an active model of asthma. CONCLUSIONS: These results indicate that Th2 cells selectively express Ca(v)1 channels that may be efficiently targeted in T lymphocytes to prevent experimental asthma.

Cav1 channels is also a story of non excitable cells: Application to calcium signalling in two different non related models.

Calcium is a second messenger essential, in all cells, for most cell functions. The spatio-temporal control of changes in intracellular calcium concentration is partly due to the activation of calcium channels. Voltage-operated calcium channels are present in excitable and non-excitable cells. If the mechanism of voltage-operated calcium channels is well known in excitable cells the Ca2+ toolkit used in non-excitable cells to activate the calcium channels is less described. Herein we discuss about very similar pathways involving voltage activated Cav1 channels in two unrelated non-excitable cells; ectoderm cells undergoing neural development and effector Th2 lymphocytes responsible for parasite elimination and also allergic diseases. We will examine the way by which these channels operate and are regulated, as well as the consequences in terms of gene transcription. Finally, we will consider the questions that remain unsolved and how they might be a challenge for the future.

FGF-activated calcium channels control neural gene expression in Xenopus.

In vertebrates, the formation of the nervous system starts at gastrulation with a process called neural induction. This process requires, at least in part, the inhibition of BMP signalling in the ectoderm by noggin, as well as FGF receptor activation and Ca2+ signalling. Our studies with Xenopus embryos suggest that an increase in intracellular Ca2+ concentration ([Ca2+]i), via dihydropyridine-sensitive Ca2+ channels (DHP-sensitive Ca2+ channels) is necessary and sufficient to direct the ectodermal cells toward a neural fate, and that Ca2+ directly controls the expression of neural genes. The mechanism by which the DHP-sensitive Ca2+ channels are activated during neural induction remains unknown. One possible mechanism is via the activation of FGF signalling. Using isolated ectoderm tissue, here we demonstrated that FGF-4 depolarises the membrane of ectodermal cells and induces an increase in [Ca2+]i. This Ca2+ increase can be blocked by SU5402, an FGF receptor inhibitor, and by DHP-sensitive Ca2+ channel antagonists. These inhibitors also block the induction of neural genes. We discuss a possible gating mechanism for the activation of DHP-sensitive Ca2+ channels via the FGF signalling pathway, which involves arachidonic acid and TRPC1 channel activation.

Early calcium increase triggers the formation of olfactory long-term memory in honeybees.

BACKGROUND: Synaptic plasticity associated with an important wave of gene transcription and protein synthesis underlies long-term memory processes. Calcium (Ca2+) plays an important role in a variety of neuronal functions and indirect evidence suggests that it may be involved in synaptic plasticity and in the regulation of gene expression correlated to long-term memory formation. The aim of this study was to determine whether Ca2+ is necessary and sufficient for inducing long-term memory formation. A suitable model to address this question is the Pavlovian appetitive conditioning of the proboscis extension reflex in the honeybee Apis mellifera, in which animals learn to associate an odor with a sucrose reward. RESULTS: By modulating the intracellular Ca2+ concentration ([Ca2+]i) in the brain, we show that: (i) blocking [Ca2+]i increase during multiple-trial conditioning selectively impairs long-term memory performance; (ii) conversely, increasing [Ca2+]i during single-trial conditioning triggers long-term memory formation; and finally, (iii) as was the case for long-term memory produced by multiple-trial conditioning, enhancement of long-term memory performance induced by a [Ca2+]i increase depends on de novo protein synthesis. CONCLUSION: Altogether our data suggest that during olfactory conditioning Ca2+ is both a necessary and a sufficient signal for the formation of protein-dependent long-term memory. Ca2+ therefore appears to act as a switch between short- and long-term storage of learned information.