Biology subjects

Cowen, M. H.

Publications and source records attributed to Cowen, M. H..

5 recordsLinked to original sources

bioRxiv2026

CRISPR inhibition of activity-dependent Arc expression in the adult mouse brain has limited effects on plasticity in visual cortex and nucleus accumbens

Neuronal activity drives long-lasting change in circuit function by inducing the expression of gene products that modulate the function of synapses. Arc is one of the most robustly activity-regulated neuronal genes, being induced broadly in neurons by a wide range of physiologically-relevant stimuli. The ability of Arc to promote internalization of AMPA-type glutamate receptors plays an important role in activity-dependent refinement of synaptic connectivity during development. However, the consequences of Arc induction for circuit plasticity in the adult brain are less well understood. We reasoned that we could test the requirement for experience-induced Arc expression in downstream plasticities by disrupting regulatory elements that mediate the inducibility of Arc transcription. To achieve this goal, we developed and validated a CRISPR-based inhibition strategy to conditionally block stimulus-induced expression of Arc in specific regions of the brains of male and female adult mice in vivo. We show that recruiting transgenic dCas9-KRAB to decrease transcriptional activity of either the promoter or the synaptic activity-regulated enhancer of the Arc gene is sufficient to block Arc protein expression in visual cortex (V1) following light exposure or in the nucleus accumbens (NAc) following cocaine administration. However, loss of Arc in V1 failed to alter plasticity of orientation selectivity and loss of Arc in NAc did not block cocaine conditioned place preference or novel object recognition memory. These data show that the relationship between Arc induction and plasticity is not universal and suggest that additional contextual factors determine the functional consequences of Arc induction for plasticity. Significance StatementArc is a neuronal activity-regulated gene whose expression is robustly induced in the adult brain by a wide range of stimuli that drive plasticity. However, the functional requirements of Arc induction for brain plasticity are incompletely understood. Here, we show that we can use transgenic mice expressing the CRISPR-based transcriptional repressor dCas9-KRAB to block stimulus-induced expression of Arc in specific regions of the adult mouse brain. Despite highly effective inhibition of Arc induction, we found that many forms of plasticity remained intact. These data deepen understanding of the contextual importance of activity-induced Arc expression in the adult brain.

neuroscience↗

bioRxiv2023

Conserved autism-associated genes tune social feeding behavior in C. elegans

Animal foraging is an essential and evolutionarily conserved behavior that occurs in social and solitary contexts, but the underlying molecular pathways are not well defined. We discover that conserved autism-associated genes (NRXN1(nrx-1), NLGN3(nlg-1), GRIA1,2,3(glr-1), GRIA2(glr-2), and GLRA2,GABRA3(avr-15)) regulate aggregate feeding in C. elegans, a simple social behavior. NRX-1 functions in chemosensory neurons (ADL and ASH) independently of its postsynaptic partner NLG-1 to regulate social feeding. Glutamate from these neurons is also crucial for aggregate feeding, acting independently of NRX-1 and NLG-1. Compared to solitary counterparts, social animals show faster presynaptic release and more presynaptic release sites in ASH neurons, with only the latter requiring nrx-1. Disruption of these distinct signaling components additively converts behavior from social to solitary. Aggregation induced by circuit activation is also dependent on nrx-1. Collectively, we find that aggregate feeding is tuned by conserved autism-associated genes through complementary synaptic mechanisms, revealing molecular principles driving social feeding. TEASERConserved autism-associated genes mediate distinct molecular and circuit signaling components that cooperate to tune C. elegans social feeding behavior.

neuroscience↗

bioRxiv2023

Structural neuroplasticity after sleep loss modifies behavior and requires neurexin and neuroligin

Sleep is conserved across species, and alterations in sleep are associated with a multitude of neurologic conditions. Structural neuroplasticity, or changes in the size, strength, number, and targets of neuronal synaptic connections, can be modified by sleep and sleep disruption. However, the causal relationships between sleep loss and neuroplasticity, behavioral impacts, and genetic perturbations are poorly understood. The C. elegans GABAergic DVB neuron undergoes structural plasticity in adult males that rewires synaptic connections and alters behavior; the rewiring is dependent on the conserved autism-associated genes NRXN1/nrx-1 and NLGN3/nlg-1. Stress exposure during sexual maturation, which overlaps with a developmental sleep period, alters DVB structural plasticity in early adulthood. Here, we use four distinct methods to ask whether sleep deprivation results in altered structural and behavioral plasticity of the DVB neuron. Following sleep deprivation using the genetic mutants (aptf-1 and npr-1), vibration stimulus, or chemo-genetic silencing of a sleep-producing neuron, we find that DVB neurite outgrowth at day 1 of adulthood. Sleep deprivation also leads to an increase in the time to spicule protraction, the behavioral output of DVB function. We find that nrx-1 and nlg-1 both function to regulate sleep loss induced DVB structural and functional changes. Lastly, differences in DVB neurite outgrowth in sleep deprived animals at day 1 are transient, with DVB morphology being indistinguishable from controls by day 3. These results show that sleep loss modifies DVB structural plasticity and its behavioral consequences. Further, we show nrx-1 and nlg-1 mediate the effect of sleep deprivation on behavior at the level of DVB structural plasticity. These insights into sleep, neuroplasticity, behavior, and conserved autism genes have important implications for the role of sleep in neurologic disease. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=128 SRC="FIGDIR/small/545788v1_figu1.gif" ALT="Figure 1"> View larger version (34K): org.highwire.dtl.DTLVardef@2320c4org.highwire.dtl.DTLVardef@3c3b86org.highwire.dtl.DTLVardef@67dc96org.highwire.dtl.DTLVardef@c3033d_HPS_FORMAT_FIGEXP M_FIG Graphical AbstractGABAergic morphologic and behavioral plasticity induced by developmental sleep deprivation depends on the conserved autism genes, nrx-1 and nlg-1 A) Sleep depriving male C. elegans during all larval sleep periods in development (aptf-1 or npr-1) or selectively inhibiting sleep during L4-adult molt (vibration or RIS silencing) results in an increase in DVB outgrowth. B) Mutations in nrx-1 (and nlg-1 in npr-1 animals) prevent sleep deprivation induced morphologic plasticity changes. C) DVB neurite outgrowth results in a functional change in spicule protraction rate as a result of increased GABAergic inhibitory signaling, which also depends on nrx-1 and nlg-1. C_FIG

neuroscience↗

bioRxiv2020

ASH1L REGULATES THE STRUCTURAL DEVELOPMENT OF NEURONAL CIRCUITRY BY MODULATING BDNF/TrkB SIGNALING IN HUMAN NEURONS

Autism spectrum disorders (ASD) are associated with defects in neuronal connectivity and are highly heritable. Genetic findings suggest that there is an overrepresentation of chromatin regulatory genes among the genes associated with ASD. ASH1 like histone lysine methyltransferase (ASH1L) was identified as a major risk factor for autism. ASH1L methylates Histone H3 on Lysine 36, which is proposed to result primarily in transcriptional activation. However, how mutations in ASH1L lead to deficits in neuronal connectivity associated with autism pathogenesis is not known. We report that ASH1L regulates neuronal morphogenesis by counteracting the catalytic activity of Polycomb Repressive complex 2 group (PRC2) in stem cell-derived human neurons. Depletion of ASH1L decreases neurite outgrowth and decreases expression of the gene encoding the neurotrophin receptor TrkB whose signaling pathway is linked to neuronal morphogenesis. This is overcome by inhibition of PRC2 activity, indicating a balance between the Trithorax group protein ASH1L and PRC2 activity determines neuronal morphology and connectivity. Thus, ASH1L epigenetically regulates neuronal connectivity by modulating the BDNF-TrkB signaling pathway, which likely contributes to the neurodevelopmental pathogenesis associated with ASD in patients with ASH1L mutations. eTOC BLURBCheon et al. report a novel epigenetic mechanism that implicates the counteracting activities of the evolutionarily conserved Trithorax (ASH1L) and Polycomb (PRC2) chromatin regulators, in the modulation of human neuronal connectivity by regulating the developmentally important TrkB-BDNF signaling pathway. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=105 SRC="FIGDIR/small/954586v1_ufig1.gif" ALT="Figure 1"> View larger version (20K): org.highwire.dtl.DTLVardef@738ee5org.highwire.dtl.DTLVardef@aa8085org.highwire.dtl.DTLVardef@1dbc315org.highwire.dtl.DTLVardef@e4bfa2_HPS_FORMAT_FIGEXP M_FIG C_FIG HIGHLIGHTSO_LIASH1L regulates neuronal morphogenesis by modulating neurotrophin signaling C_LIO_LICounteracting activities of Trithorax (ASH1L) and Polycomb (PRC2) affect neuronal arborization C_LIO_LILoss of ASH1L modulates growth cone size in human neurons C_LI

neuroscience↗

bioRxiv2018

Human neurons from Christianson syndrome iPSCs reveal allele-specific responses to rescue strategies

Human genetic disorders provide a powerful lens to understanding the human brain. Induced pluripotent stem cells (iPSC) represent an important, new resource for mechanistic studies and therapeutic development. Christianson syndrome (CS), an X-linked neurological disorder with attenuation of brain growth postnatally (postnatal microcephaly), is caused by mutations in SLC9A6, the gene encoding endosomal Na+/H+ exchanger 6 (NHE6). We developed CS iPSC lines from patients with a mutational spectrum, as well as robust biologically-related and isogenic controls. We demonstrate that mutations in CS lead to loss of protein function by a variety of mechanisms. Regardless of mutation, all patient-derived neurons demonstrate reduced neurite growth and arborization, likely underlying diminished postnatal brain growth in patients. Additionally, phenotype rescue strategies show allele-specific responses: a gene replacement strategy shows efficacy in nonsense mutations but not in a missense mutation, whereas application of exogenous trophic factors (BDNF or IGF-1) rescues arborization phenotypes across all mutations. Our data emphasize the important principle of personalized medicine whereby success of some therapeutic strategies may be more linked to patient genotype than others.

neuroscience↗