Biology subjects

Chavez, J.

Publications and source records attributed to Chavez, J..

11 recordsLinked to original sources

bioRxiv2026

Early life Oxytocin treatment Attenuates Seizure Susceptibility in Male, but not Female, Fmr1-KO Mice

Fragile X syndrome (FXS) is the leading inherited cause of intellectual disability, and is frequently accompanied by seizures. Early-life treatment with the hormone oxytocin (OXT) improves social behavior and cognitive function in rodent models of autism with intellectual disability, including FXS, but potential OXT treatment effects on seizure susceptibility have not been evaluated. Here we tested, in both sexes, if intranasal OXT (iOXT) or saline (iSAL) during the second postnatal week reduces audiogenic seizures (AGS) in the Fmr1-Knockout (KO) mouse model of FXS. OXT given daily from postnatal day (P) 7 to P13 significantly reduced the incidence and severity of AGS and the latency to seize in adult male Fmr1-KOs. Female KOs exhibited less severe seizures that were unaffected by treatment. Wild type mice did not exhibit AGS independent of treatment. To test if antiepileptic effects of iOXT are age-dependent, a separate cohort received iOXT daily from P30 to P36. Male KOs receiving later treatments exhibited robust seizures that were comparable between OXT- and SAL-treatment groups, suggesting that OXTs enduring antiepileptic effects are confined to early postnatal treatments. Tests of acute OXT effects in adulthood demonstrated an attenuation of male Fmr1-KO AGS at testing 30-60 min and 1 day post-treatment but these effects were not evident 15 days later. These findings reveal marked sex differences in the propensity for audiogenic seizures in Fmr1-KO mice and demonstrate that early-life OXT treatment mitigates seizure susceptibility in males FXS model mice.

neuroscience↗

bioRxiv2025

The zinc-finger protein POGZ associates with Polycomb repressive complex 1 to regulate bone morphogenetic protein signaling during neuronal differentiation

Polycomb Repressive Complex 1 (PRC1) is a family of epigenetic regulators critical for mammalian development. Elucidating PRC1 composition and function across cell types and developmental stages is key to understanding the epigenetic regulation of cell fate determination. In this study, we discovered POGZ, a prominent Autism Spectrum Disorder (ASD) risk factor, as a novel component of PRC1.6, forming the PRC1.6-POGZ complex. Functional assays revealed that POGZ elicits transcriptional repression that is dependent on RING1B expression. Analysis of publicly available ChIP-Seq data showed that POGZ highly colocalizes with RING1B and HP1{gamma}, two PRC1.6 components, at genes involved in multiple aspects of transcriptional regulation in the embryonic mouse cortex. Although Pogz knockout (KO) does not compromise stem cell pluripotency, Pogz ablation in neuronal progenitor cells (NPCs) led to widespread transcriptomic dysregulation with failed activation of key neuronal genes. Finally, we demonstrated that PRC1.6-POGZ regulates neuronal differentiation by repressing the bone morphogenetic protein (BMP) signaling pathway. These findings reveal a mechanism by which PRC1 and POGZ coordinate transcriptional regulation during neuronal differentiation, which offers insights into how disruptions in this pathway may contribute to neurodevelopmental disorders such as ASD.

biochemistry↗

bioRxiv2024

Early-life Oxytocin Rescues Hippocampal Synaptic Plasticity and Episodic Memory in a Mouse Model of Fragile X Syndrome

Cognitive disabilities including impairments to episodic memory are debilitating features of autism spectrum disorder (ASD). Here we report that early-life treatment with oxytocin (OXT) fully restores episodic memory and associated synaptic plasticity in a rodent model of an ASD. Fmr1-knockout (KO) mice -- which mimic the single gene mutation in Fragile X Syndrome -- failed to encode three basic elements of an episode (identity, location, and temporal order) during a first time, unrewarded encounter with a set of cues. Intranasal administration of OXT during the second postnatal week eliminated each of these impairments in mice tested in adulthood. OXT treatment during the second, but not fifth, postnatal week also corrected pronounced defects in two distinct forms of hippocampal Long-Term Potentiation (LTP). Rescue of LTP in lateral perforant path (LPP) to dentate gyrus synapses was linked to recovery of NMDAR-gated synaptic responses, which are otherwise profoundly reduced in the mutant LPP. LTP induced by a threshold theta burst stimulation protocol in CA3-CA1 synapses was severely impaired in adult Fmr1-KOs as was a previously unreported post-induction growth phase for potentiation. Both effects were restored in adult Fmr1-KOs given early OXT treatment. Infusion of OXT into adult Fmr1-KO hippocampal slices normalized LTP in CA1 but had no effect on the defective potentiation (or NMDAR-mediated EPSCs) at LPP-dentate gyrus synapses. These results show that severe, autism-related defects in cognition critical to memory, as evident in a rodent model, are reversible and that an early-life therapeutic intervention can effect an enduring restoration of function.

neuroscience↗

bioRxiv2024

Enhanced endogenous gene tagging in human induced pluripotent stem cells via AAV6-mediated donor delivery

Systematically tagging endogenous proteins with fluorescent markers in human induced pluripotent stem cells (hiPSCs) allows observation of live cell dynamics in different cell states. However, the precise insertion of fluorescent proteins into live cells via CRISPR/Cas9-induced editing relies on homology-directed repair (HDR). The nonhomologous end-joining (NHEJ) DNA repair pathway often outcompetes HDR, resulting in irreversible insertions and deletions (INDELs) and low knock-in efficiency. Recognizing successful HDR-mediated tagging events is an additional challenge when the target gene is not expressed in stem cells and successful tagging cannot be immediately observed. To address these challenges, we used: 1) adeno-associated virus serotype 6 (AAV6) mediated DNA donors at optimized multiplicity of infection (MOI) to deliver tag payloads at maximal efficiency; 2) titrated, multiplexed Cas9:gRNA ribonucleo-protein (RNP) amounts to assure balanced HDR/INDEL frequency among conditions; 3) long-amplicon droplet digital PCR (ddPCR) to measure the frequency of HDR-generated alleles in edited pools; and 4) simultaneous Inference of CRISPR Edits (ICE) to detect and thereby avoid conditions significantly saturated (>50%) with INDELs. These approaches enabled us to identify efficient and accurate editing conditions and recover tagged cells, including cells tagged at loci not expressed in stem cells. Together these steps allowed us to develop an efficient methodology and workflow to clonally isolate directly from an ideal cell pool with optimal HDR and minimized INDEL frequencies. Using this approach, we achieved both monoallelic and biallelic insertion of fluorescent markers into four genes that are turned on during differentiation but not initially expressed in hiPSCs, where direct selection of tagged cells based on fluorescence was impossible: TBR2, TBXT, CDH2 (pro-differentiation and pro-migratory genes), and CDH5 (endothelial specific gene). Through a systematic evaluation of various gRNA sequences and RNP concentrations, we identified conditions for each gene that achieved high HDR frequencies, peaking at 38.6%, while also avoiding conditions saturated with INDELs, where isolation of clones with a tagged allele in trans with an unedited allele is difficult. Over-all, this methodology enhances the efficiency of fluorescent tag knock-in at genes not expressed in hiPSCs, facilitating reliable image-based observation of cellular processes, and enables recovery of accurately edited mono- and biallelically tagged clones. We standardized these approaches to yield an efficient and general workflow for introducing large HDR mediated knock-ins into hiPSCs.

cell biology↗

bioRxiv2023

Ectopic transcription due to inappropriately inherited histone methylation may interfere with the ongoing function of terminally differentiated cells

How mutations in histone modifying enzymes lead to neurodevelopmental disorders is unknown. We took advantage of the invariant embryonic lineage and adult nervous system in C. elegans to investigate a double mutant between spr-5/Lsd1/Kdm1a (H3K4me1/2 demethylase) and met-2/Setdb1 (H3K9 methyltransferase). We demonstrate that spr-5; met-2 double mutant worms have a severe chemotaxis defect caused by the ectopic expression of germline genes in somatic tissues. Despite this behavioral defect, we observe few embryonic lineage alterations and an intact adult nervous system. This raises the possibility that the abnormal chemotaxis behavior may be due to ongoing defects in terminally differentiated cells rather than alterations in development. Remarkably, we found that shutting off the ectopic germline expression rescues normal chemotaxis in the same spr-5; met-2 adult worms that had a chemotaxis defect earlier. This suggests that ongoing inappropriate transcription can block normal behavior in an intact nervous system. Based on these data, it is possible that the intellectual disability and altered behavior observed in human neurodevelopmental syndromes caused by mutations in histone modifying enzymes could be due to ongoing ectopic transcription and may be reversible.

developmental biology↗

bioRxiv2022

Microglia Depletion Selectively Eliminates a Singular Form of Hippocampal Long Term Potentiation

There has been considerable recent interest in the possibility that microglia contribute to synaptic plasticity and some forms of learning. We report here that elimination of the cells in young adult male mice with a 7-12 day treatment with an antagonist (PLX5622) of the colony stimulating factor 1 receptor causes a profound but highly selective impairment to long-term potentiation (LTP) expressed by lateral perforant path (LPP) synapses with the dentate gyrus. Input/output functions and frequency facilitation to repetitive stimulation were not measurably affected. Direct infusion of PLX5622 into slices from naiive mice did not reduce the magnitude of LPP-LTP. Microglial depletion had no detectable effect on LTP in either the medial perforant path input to the dentate gyrus or the Schaffer-commissural projections between fields CA3 and CA1. We conclude that microglia discretely regulate the unusual form of LTP expressed by the LPP and thus exert region-specific effects on circuit function within hippocampus.

neuroscience↗

bioRxiv2021

Evaluating the role of coevolution in a horizontally transmitted mutualism

Mutualism depends on the alignment of host and symbiont fitness. Horizontal transmission can readily decouple fitness interests, yet horizontally transmitted mutualisms are common in nature. We hypothesized that pairwise coevolution and specialization in host-symbiont interactions underlies the maintenance of cooperation in a horizontally transmitted mutualism. Alternatively, we predicted selection by multiple host species may select for cooperative traits in a generalist symbiont through diffuse coevolution. We tested for signatures of pairwise coevolutionary change between the squash bug Anasa tristis and its horizontally acquired bacterial symbiont Caballeronia spp. by measuring local adaptation. We found no evidence for local adaptation between sympatric combinations of A. tristis squash bugs and Caballeronia spp. across their native geographic range. To test for diffuse coevolution, we performed reciprocal inoculations to test for specialization between three Anasa host species and Caballeronia spp. symbionts isolated from conspecific hosts. We observed no evidence of specialization across host species. Our results demonstrate generalist dynamics underlie the interaction between Anasa insect hosts and their Caballeronia spp. symbionts. Specifically, diffuse coevolution between multiple host species with a shared generalist symbiont may maintain cooperative traits despite horizontal transmission.

evolutionary biology↗

bioRxiv2021

AUTS2 controls neuronal lineage choice through a novel PRC1-independent complex and BMP inhibition

Despite a prominent risk factor for Neurodevelopmental disorders (NDD), it remains unclear how Autism Susceptibility Candidate 2 (AUTS2) controls the neurodevelopmental program. Our studies investigated the role of AUTS2 in neuronal differentiation and discovered that AUTS2, together with WDR68 and SKI, forms a novel protein complex (AWS) specifically in neuronal progenitors and promotes neuronal differentiation through inhibiting BMP signaling. Genomic and biochemical analyses demonstrated that the AWS complex achieves this effect by recruiting the CUL4 E3 ubiquitin ligase complex to mediate poly-ubiquitination and subsequent proteasomal degradation of phosphorylated SMAD1/5/9. Furthermore, using primary cortical neurons, we observed aberrant BMP signaling and dysregulated expression of neuronal genes upon manipulating the AWS complex, indicating that the AWS-CUL4-BMP axis plays a role in regulating neuronal lineage specification in vivo. Thus, our findings uncover a sophisticated cellular signaling network mobilized by a prominent NDD risk factor, presenting multiple potential therapeutic targets for NDD.

biochemistry↗

bioRxiv2021

A projectome of the bumblebee central complex

Insects have evolved diverse and remarkable strategies for navigating in various ecologies all over the world. Regardless of species, insects share the presence of a group of morphologically conserved neuropils known collectively as the central complex (CX). The CX is a navigational hub, involved in sensory integration and coordinated motor activity. Despite the fact that our understanding of navigational behavior comes predominantly from ants and bees, most of what we know about the underlying neural circuitry of such behavior comes from work in fruit flies. Here we aim to close this gap, by providing the first comprehensive map of all major columnar neurons and their projection patterns in the CX of a bee. We find numerous components of the circuit that appear to be highly conserved between the fly and the bee, but also highlight several key differences which are likely to have important functional ramifications.

neuroscience↗

bioRxiv2020

Programmatic access to bacterial regulatory networks with regutools

SummaryRegulonDB has collected, harmonized and centralized data from hundreds of experiments for nearly two decades and is considered a point of reference for transcriptional regulation in Escherichia coli K12. Here, we present the regutools R package to facilitate programmatic access to RegulonDB data in computational biology. regutools gives researchers the possibility of writing reproducible workflows with automated queries to RegulonDB. The regutools package serves as a bridge between RegulonDB data and the Bioconductor ecosystem by reusing the data structures and statistical methods powered by other Bioconductor packages. We demonstrate the integration of regutools with Bioconductor by analyzing transcription factor DNA binding sites and transcriptional regulatory networks from RegulonDB. We anticipate that regutools will serve as a useful building block in our progress to further our understanding of gene regulatory networks. Availability and Implementationregutools is an R package available through Bioconductor at bioconductor.org/packages/regutools. Contactgithub.com/ComunidadBioInfo/regutools, lcolladotor@gmail.com, alejandro.reyes.ds@gmail.com.

bioinformatics↗

bioRxiv2020

A peptidergic amygdala microcircuit modulates sexually dimorphic contextual fear

Trauma can cause dysfunctional fear regulation leading some to develop disorders like post-traumatic stress disorder (PTSD). The amygdala regulates fear, and, PACAP and PAC1 receptors are linked to PTSD symptom severity at genetic/epigenetic levels, with a strong link in females with PTSD. We discovered a PACAPergic projection from the basomedial amygdala (BMA) to the medial intercalated cells (mICCs). In vivo optogenetic stimulation of this pathway increased cfos expression in mICCs, decreased fear retention and increased fear extinction. Selective deletion of PAC1 receptors from the mICCs in females reduced fear acquisition, but enhanced fear generalization and reduced fear extinction in males. Optogenetic stimulation of the BMA-mICCs PACAPergic pathway produced excitatory postsynaptic currents (EPSCs) in mICCs neurons, which was enhanced by PAC1 receptor antagonist, PACAP 6-38. Our findings show that mICCs modulate contextual fear in a dynamic and sex-dependent manner via the microcircuit containing the BMA and mICCs, dependent on behavioral state.

neuroscience↗