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The SynGAP protein is a major regulator of synapse biology and neural circuit function. Genetic variants linked to epilepsy and intellectual disability disrupt synaptic function and neural excitability. SynGAP has been involved in multiple signaling pathways and can regulate small GTPases with very different roles. Yet, the molecular bases behind this pleiotropy are poorly understood. We hypothesize that different SynGAP isoforms will mediate different sets of functions and that deciphering their spatio‐temporal expression and subcellular localization will accelerate understanding their multiple functions. Using isoform‐specific antibodies recognizing SynGAP in mouse and human samples we found distinctive developmental expression patterns for all SynGAP isoforms in five mouse brain areas. Particularly noticeable was the delayed expression of SynGAP‐α1 isoforms, which directly bind to postsynaptic density‐95, in cortex and hippocampus during the first 2 weeks of postnatal development. Suggesting that during this period other isoforms would have a more prominent role. Furthermore, we observed subcellular localization differences between isoforms, particularly throughout postnatal development. Consistent with previous reports, SynGAP was enriched in the postsynaptic density in the mature forebrain. However, SynGAP was predominantly found in non‐synaptic locations in a period of early postnatal development highly sensitive to SynGAP levels. While, α1 isoforms were always found enriched in the postsynaptic density, α2 isoforms changed from a non‐synaptic to a mostly postsynaptic density localization with age and β isoforms were always found enriched in non‐synaptic locations. The differential expression and subcellular distribution of SynGAP isoforms may contribute to isoform‐specific regulation of small GTPases, explaining SynGAP pleiotropy., Syngap1 gene encodes for different synaptic Ras/Rap GTPase‐activating (SynGAP) isoforms which are key for brain function. SynGAP C‐termini splice variants show different spatio‐temporal expression and subcellular localization in the developing mouse brain. This study reveals a non‐synaptic and heterogenous role of SynGAP spliced variants. Depicted abundance differences only allow relative comparison within a given tissue (top panel), postnatal age (PND, middle panel), or subcellular distribution (bottom panel). Ctx, cortex; Hip, hippocampus; Str, striatum; OB, Olfactory Bulb; Crb, cerebellum and tSynGAP, total SynGAP.

Cannabis is the most consumed illicit drug worldwide. Its principal psychoactive component, Δ9-tetrahydrocannabinol (THC), affects multiple brain functions, including cognitive performance, by modulating cannabinoid type-1 (CB1) receptors. These receptors are strongly enriched in presynaptic terminals, where they modulate neurotransmitter release. We analyzed, through a proteomic screening of hippocampal synaptosomal fractions, those proteins and pathways modulated 3 h after a single administration of an amnesic dose of THC (10 mg/kg, i.p.). Using an isobaric labeling approach, we identified 2040 proteins, 1911 of them previously reported in synaptic proteomes, confirming the synaptic content enrichment of the samples. Initial analysis revealed a significant alteration of 122 proteins, where 42 increased and 80 decreased their expression. Gene set enrichment analysis indicated an over-representation of mitochondrial associated functions and cellular metabolic processes. A second analysis focusing on extreme changes revealed 28 proteins with altered expression after THC treatment, 15 of them up-regulated and 13 down-regulated. Using a network topology-based scoring algorithm we identified those proteins in the mouse proteome with the greatest association to the 28 modulated proteins. This analysis pinpointed a significant alteration of the proteasome function, since top scoring proteins were related to the proteasome system (PS), a protein complex involved in ATP-dependent protein degradation. In this regard, we observed that THC decreases 20S proteasome chymotrypsin-like protease activity in the hippocampus. Our data describe for the first time the modulation of the PS in the hippocampus following THC administration under amnesic conditions that may contribute to an aberrant plasticity at synapses. This study was supported by Grants from the Ministerio de Economía, Innovación y Competitividad (MINECO) (#BFU2015-68568-P (MINECO/FEDER, UE) to A.O., #BFU2015-69717-P (MINECO/FEDER, UE) to RRV and AB, #RYC-2011-08391 to AB, #SAF2017-90664-REDT to RRV and AB, #SAF2014-59648-P and #SAF2017-84060-R to R.M.; a grant from the Instituto de Salud Carlos III (#RD16/0017/0020) to R.M.; Generalitat de Catalunya (2017SGR-669 to R.M. and 2017SGR1776 to RRV and AB) and ICREA (Institució Catalana de Recerca i Estudis Avançats) Academia to A.O. and R.M. Mass spectrometric analyses were performed at the CRG/UPF Proteomics Unit which is part of the of Proteored, PRB3 and is supported by grant PT17/0019, of the PE I + D + i 2013-2016, funded by ISCIII and ERDF. Grant “Unidad de Excelencia María de Maeztu”, funded by the MINECO (#MDM-2014-0370); PLAN E (Plan Español para el Estímulo de la Economía y el Empleo); FEDER funding is also acknowledged

Telomeres protect against genome instability and participate in chromosomal movements during gametogenesis, especially in meiosis. Thus, maintaining telomere structure and telomeric length is essential to both cell integrity and the production of germ cells. As a result, alteration of telomere homeostasis in the germ line may result in the generation of aneuploid gametes or gametogenesis disruption, triggering fertility problems. In this work, we provide an overview on fundamental aspects of the literature regarding the organization of telomeres in mammalian germ cells, paying special attention to telomere structure and function, as well as the maintenance of telomeric length during gametogenesis. Moreover, we discuss the different roles recently described for telomerase and TERRA in maintaining telomere functionality. Finally, we review how new findings in the field of reproductive biology underscore the role of telomere homeostasis as a potential biomarker for infertility. Overall, we anticipate that the study of telomere stability and equilibrium will contribute to improve diagnoses of patients; assess the risk of infertility in the offspring; and in turn, find new treatments.

Telomeres are ribonucleoprotein structures at the end of chromosomes composed of telomeric DNA, specific-binding proteins, and noncoding RNA (TERRA). Despite their importance in preventing chromosome instability, little is known about the cross talk between these three elements during the formation of the germ line. Here, we provide evidence that both TERRA and the telomerase enzymatic subunit (TERT) are components of telomeres in mammalian germ cells. We found that TERRA colocalizes with telomeres during mammalian meiosis and that its expression progressively increases during spermatogenesis until the beginning of spermiogenesis. While both TERRA levels and distribution would be regulated in a gender-specific manner, telomere-TERT colocalization appears to be regulated based on species-specific characteristics of the telomeric structure. Moreover, we found that TERT localization at telomeres is maintained throughout spermatogenesis as a structural component without affecting telomere elongation. Our results represent the first evidence of colocalization between telomerase and telomeres during mammalian gametogenesis.

Bisphenol A (BPA) is a 'weak' endocrine disruptor. The effect of BPA on human reproduction is controversial but has been related to meiotic anomalies, recurrent spontaneous abortion, abnormal karyotypes, the diminishing of oocyte survival, delay in meiotic pro- gression and an elevated rate of MLH1 foci in vitro. The aim of this study is to characterize the gene expression of human fetal oocytes in culture as well as to evaluate the effect of BPA in cultured human oocytes. To accomplish our objective, 12 ovaries from 6 euploid fetuses were used. The ovarian fetal tissue was cultivated in two groups: control group and BPA group (BPA30 mM). The cultures were analyzed at T0 and after 7 (T7), 14 (T14) and 21 (T21) days of culture. Evaluation of gene expression was performed by real-time PCR (RT -PCR), with the evaluated genes being: Smc1b, Sycp1 (pairing-synapsis), Spo11, Rpa, H2ax, Mlh1 and Blm (double-strand break (DSBs) generation, sig- naling and repair), Era, Erb and Errg (estrogen receptors), Stra8 and Nalp5 (markers of meiotic progression). Oocytes from ovaries cultured and treated with BPA show changes in the expression of Spo11, H2ax and Blm genes, with a significant increase from 3- to 5-fold (P ≤ 0.05). Finally, Rpa, showed a 100-fold increment (P ≤ 0.01). Era, Erb and Errg genes showed a BPA up-regulation of 2 -4-fold in all of the culture times (P ≤ 0.05). Oocytes exposed to BPA showed an up-regulation of genes involved in DSB generation, signaling and repair except by Mlh1. Thus, BPA can modify the gene expression pattern, which may explain the effects of BPA on female germ cells.