Neuronal survival induced by neurotrophins requires calmodulin

It has been reported that phosphoinositide 3-kinase (PI 3-kinase) and its downstream target, protein kinase B (PKB), play a central role in the signaling of cell survival triggered by neurotrophins (NTs). In this report, we have analyzed the involvement of Ca2+ and calmodulin (CaM) in the activation of the PKB induced by NTs. We have found that reduction of intracellular Ca2+ concentration or functional blockade of CaM abolished NGF-induced activation of PKB in PC12 cells. Similar results were obtained in cultures of chicken spinal cord motoneurons treated with brain-derived neurotrophic factor (BDNF). Moreover, CaM inhibition prevented the cell survival triggered by NGF or BDNF. This effect was counteracted by the transient expression of constitutive active forms of the PKB, indicating that CaM regulates NT-induced cell survival through the activation of the PKB. We have investigated the mechanisms whereby CaM regulates the activation of the PKB, and we have found that CaM was necessary for the proper generation and/or accumulation of the products of the PI 3-kinase in intact cells

FLRT2 and FLRT3 Cooperate in Maintaining the Tangential Migratory Streams of Cortical Interneurons during Development

Neuron migration is a hallmark of nervous system development that allows gathering of neurons from different origins for assembling of functional neuronal circuits. Cortical inhibitory interneurons arise in the ventral telencephalon and migrate tangentially forming three transient migratory streams in the cortex before reaching the final laminar destination. Although migration defects lead to the disruption of inhibitory circuits and are linked to aspects of psychiatric disorders such as autism and schizophrenia, the molecular mechanisms controlling cortical interneuron development and final layer positioning are incompletely understood. Here, we show that mouse embryos with a double deletion of FLRT2 and FLRT3 genes encoding cell adhesion molecules exhibit an abnormal distribution of interneurons within the streams during development, which in turn, affect the layering of somatostatin+ interneurons postnatally. Mechanistically, FLRT2 and FLRT3 proteins act in a noncell-autonomous manner, possibly through a repulsive mechanism. In support of such a conclusion, double knockouts deficient in the repulsive receptors for FLRTs, Unc5B and Unc5D, also display interneuron defects during development, similar to the FLRT2/FLRT3 mutants. Moreover, FLRT proteins are chemorepellent ligands for developing interneurons in vitro, an effect that is in part dependent on FLRT-Unc5 interaction. Together, we propose that FLRTs act through Unc5 receptors to control cortical interneuron distribution in a mechanism that involves cell repulsion.This work was supported by grants from the Spanish Ministry of Science and Innovation (BFU2010-1805, BFU2013-48563-P, and PGC2018-101910-B-I00 to J.E. and BES-2014-067618 to P.M.-O.), FP7-PEOPLE-2011-CIG (PCIG9-GA-2011-293980 to J.E.), the Max-Planck Society (R.K.), and the Jade Plus Fellowship Program 2011–2014 (C.F.). We thank Tristan Rodríguez (Sox1-Cre line) and Anne Eichmann (Unc5Blx line) for the transgenic mice; Michèle Studer for the vasointestinal peptide probe; Eve Seuntjens and Veronique van den Berghe for scientific discussion; Inmaculada Segura for reading the manuscript; Serafí Cambray, Alex Espinós, Ma José Menal, Inma Montoliu, Montse Ortega, Noel Pérez, Sònia Rius, Marc Tarrés, and the University of Lleida Scientific and Technical Services for technical assistance, and the University of Lleida animal house staff facility for animal care

A dominant negative mutation uncovers cooperative control of caudal Wolffian duct development by Sprouty genes

The Wolffian ducts (WD) are paired epithelial tubules central to the development of the mammalian genitourinary tract. Outgrowths from the WD known as the ureteric buds (UB) generate the collecting ducts of the kidney. Later during development, the caudal portion of the WD will form the vas deferens, epididymis and seminal vesicle in males, and will degenerate in females. While the genetic pathways controlling the development of the UB are firmly established, less is known about those governing development of WD portions caudal to the UB. Sprouty proteins are inhibitors of receptor tyrosine kinase (RTK) signaling in vivo. We have recently shown that homozygous mutation of a conserved tyrosine (Tyr53) of Spry1 results in UB defects indistinguishable from that of Spry1 null mice. Here, we show that heterozygosity for the Spry1 Y53A allele causes caudal WD developmental defects consisting of ectopically branched seminal vesicles in males and persistent WD in females, without affecting kidney development. Detailed analysis reveals that this phenotype also occurs in Spry1+/- mice but with a much lower penetrance, indicating that removal of tyrosine 53 generates a dominant negative mutation in vivo. Supporting this notion, concomitant deletion of one allele of Spry1 and Spry2 also recapitulates the genital phenotype of Spry1Y53A/+ mice with high penetrance. Mechanistically, we show that unlike the effects of Spry1 in kidney development, these caudal WD defects are independent of Ret signaling, but can be completely rescued by lowering the genetic dosage of Fgf10. In conclusion, mutation of tyrosine 53 of Spry1 generates a dominant negative allele that uncovers fine-tuning of caudal WD development by Sprouty genes.Open Access funding provided thanks to the CRUE-CSIC agreement with Springer Nature. This work was supported by grants BFU2017-83646-P (MINECO) and PID2020-114947 GB-I00 (MCIU) (both supported by funds from AEI/FEDER, UE) to ME. MV was supported by a predoctoral fellowship from AGAUR. GA and CA and GA are supported by a fellowship from Universitat de Lleida. SC was supported by a Cofund action from the Marie Curie program of the E

Trisomy 8, A Cytogenetic Abnormality In Myelodysplastic Syndromes, Is Constitutional Or Not?

Isolated trisomy 8 is not considered presumptive evidence of myelodysplastic syndrome (MDS) in cases without minimal morphological criteria. One reason given is that trisomy 8 (+8) can be found as a constitutional mosaicism (cT8M). We tried to clarify the incidence of cT8M in myeloid neoplasms, specifically in MDS, and the diagnostic value of isolated +8 in MDS. Twenty-two MDS and 10 other myeloid neoplasms carrying +8 were studied. Trisomy 8 was determined in peripheral blood by conventional cytogenetics (CC) and on granulocytes, CD3+ lymphocytes and oral mucosa cells by fluorescence in situ hybridization (FISH). In peripheral blood CC, +8 was seen in 4/32 patients. By FISH, only one patient with chronic myelomonocytic leukemia showed +8 in all cell samples and was interpreted as a cT8M. In our series +8 was acquired in all MDS. Probably, once discarded cT8M by FISH from CD3+ lymphocytes and non-hematological cells, +8 should be considered with enough evidence to MDS

Identification of gene mutations and fusion genes in patients with Sézary Syndrome

Sézary syndrome is a leukemic form of cutaneous T-cell lymphoma with an aggressive clinical course. The genetic etiology of the disease is poorly understood, with chromosomal abnormalities and mutations in some genes being involved in the disease. The goal of our study was to understand the genetic basis of the disease by looking for driver gene mutations and fusion genes in 15 erythrodermic patients with circulating Sézary cells, 14 of them fulfilling the diagnostic criteria of Sézary syndrome. We have discovered genes that could be involved in the pathogenesis of Sézary syndrome. Some of the genes that are affected by somatic point mutations include ITPR1, ITPR2, DSC1, RIPK2, IL6, and RAG2, with some of them mutated in more than one patient. We observed several somatic copy number variations shared between patients, including deletions and duplications of large segments of chromosome 17. Genes with potential function in the T-cell receptor signaling pathway and tumorigenesis were disrupted in Sézary syndrome patients, for example, CBLB, RASA2, BCL7C, RAMP3, TBRG4, and DAD1. Furthermore, we discovered several fusion events of interest involving RASA2, NFKB2, BCR, FASN, ZEB1, TYK2, and SGMS1. Our work has implications for the development of potential therapeutic approaches for this aggressive disease