Biology subjects

Blakely, R. D.

Publications and source records attributed to Blakely, R. D..

5 recordsLinked to original sources

bioRxiv2025

Peripheral Inflammation Limits Serotonin Neuron Signaling Capacity via Serotonergic IL-1R1 to Reduce Neuronal Excitability and Enhance Serotonin Clearance

Neurobehavioral disorders, ranging from depression to schizophrenia, have been found to display immune system alterations. The high incidence of comorbidity of these disorders, particularly depression, with chronic inflammatory conditions suggests shared mechanisms contributing to the manifestation of these conditions. We have previously shown that peripheral modulation of the innate immune system in mice rapidly triggers enhanced serotonin (5-HT) clearance in vivo associated with increased anxiety- and despair-like behaviors that can be suppressed by serotonergic elimination of p38 MAPK. Forebrain-projecting 5-HT synthesizing neurons of the dorsal raphe nucleus (DRN5-HT) play a key role in regulating behaviors related to mood and anxiety and whose perturbations are observed in multiple affective disorders. Here we identify molecular and circuit-level mechanisms that can translate peripheral innate immune system activation into changes in 5-HT signaling capacity. Using whole cell patch clamp recordings from acute midbrain slices, we demonstrate that the proinflammatory cytokine, IL-1{beta}, acts cell autonomously through its receptor, IL-1R1, via the p38 MAPK signaling pathway to rapidly inhibit firing of DRN5-HT neurons. In the dorsal hippocampus, we found that as with acute, peripheral lipopolysaccharide (LPS) administration, local injections of IL-1{beta} rapidly enhance 5-HT clearance as assessed by in vivo chronoamperometry. Like IL-1{beta}, TNF also acts via a serotonergic p38 MAPK dependent pathway to reduce excitability of DRN5-HT neurons. Immunocytochemical studies reveal that, IL-1R1, is nonuniformly expressed by DRN5-HT neurons and is required for LPS-induced inhibition of these cells as detected by cFos activation, with sex-dependent patterns evident. Moreover, we detected both DRN5-HT IL-1R1-dependent and -independent LPS-mediated changes in cFos changes in forbrain projection areas. Our findings support a growing appreciation that serotoninergic neurons contribute to changes in CNS physiology and behavior following peripheral immune activation. More specifically, our studies attest to a functional role of serotonergic IL-1R1 in mediating IL-1{beta} following peripheral innate immune activation, effects likely to arise both from changes in diminished 5-HT neuron excitability and elevated 5-HT clearance.

neuroscience↗

bioRxiv2023

Glial swip-10 expression controls systemic mitochondrial function, oxidative stress, and neuronal viability via copper ion homeostasis

Cuprous copper (Cu(I)) is an essential cofactor for enzymes supporting many cellular functions including mitochondrial respiration and suppression of oxidative stress. Neurons are particularly dependent on these pathways, with multiple neurodegenerative diseases, including Alzheimers disease (AD), Parkinsons disease, associated with their dysfunction. Key features of Cu(I) contributions to neuronal health in vivo remain to be defined, owing largely to the complex processes involved in Cu(I) production, intracellular transport, and systemic redistribution. Here, we provide genetic and pharmacological evidence that swip-10 is a critical determinant of systemic Cu(I) levels in C. elegans, with deletion leading to systemic deficits in mitochondrial respiration, production of oxidative stress, and neurodegeneration. These phenotypes can be reproduced in wild-type worms by Cu(I)-specific chelation and offset in swip-10 mutants by growth on the Cu(I) enhancing molecule elesclomol, as well as by glial expression of wildtype swip-10. MBLAC1, the most closely related mammalian ortholog to swip-10, encodes for a pre-mRNA processing enzyme for H3 histone, a protein whose actions surprisingly include an enzymatic capacity to produce Cu(I) via the reduction of Cu(II). Moreover, genome-wide association studies and post-mortem molecular studies implicate reductions of MBLAC1 expression in risk for AD with cardiovascular disease comorbidity. Consistent with these studies, we demonstrate that the deposition of {beta}-amyloid plaques, an AD pathological hallmark, in worms engineered to express human A{beta}1-42, is greatly exaggerated by mutation of swip-10. Together, these studies identify a novel glial-expressed, and pathway for Cu(I) production that may be targeted for the treatment of AD and other neurodegenerative diseases. Significance StatementDevastating neurodegenerative diseases such as Alzheimers disease, and Parkinsons disease are associated with disruptions in copper (Cu) homeostasis. Alterations in Cu(I) give rise to increased oxidative stress burden, mitochondrial and metabolic dysfunction, and can accelerate production and/or potentiate toxicity of disease-associated protein aggregates. Here, using the model system Caenorhabditis elegans, we establish a role for the gene swip-10 in systemic Cu(I) homeostasis. Perturbation of this pathway in worms recapitulates biochemical, histological, and pathological features seen in human neurodegenerative disease. We reveal that these changes can be suppressed pharmacologically and arise when swip-10 expression is eliminated from glial cells. Our work implicates swip-10 and orthologs as key players in Cu(I) homeostasis that may be exploitable to treat multiple neurodegenerative diseases.

neuroscience↗

bioRxiv2022

DAT Val559 Mice Exhibit Compulsive Behavior Under Devalued Reward Conditions Accompanied by Cellular and Pharmacological Changes

Identified across multiple psychiatric disorders, the dopamine (DA) transporter (DAT) Ala559Val substitution triggers non-vesicular, anomalous DA efflux (ADE), perturbing DA neurotransmission and behavior. We have shown that DAT Val559 mice display a waiting impulsivity and changes in cognitive performance associated with enhanced reward motivation. Here, utilizing a within-subject, lever-pressing paradigm designed to bias the formation of goal-directed or habitual behavior, we demonstrate that DAT Val559 mice modulate their nose-poke behavior appropriately to match context, but demonstrate a perseverative checking behavior. Although DAT Val559 mice display no issues with the cognitive flexibility required to acquire and re-learn a visual pairwise discrimination task, devaluation of reward evoked habitual reward seeking in DAT Val559 mutants in operant tasks regardless of reinforcement schedule. The direct DA agonist apomorphine also elicits locomotor stereotypies in DAT Val559, but not WT mice. Our observation that dendritic spine density is increased in the dorsal medial striatum (DMS) of DAT Val559 mice speaks to an imbalance in striatal circuitry that might underlie the propensity of DAT Val559 mutants to exhibit compulsive behaviors when reward is devalued. Thus, DAT Val559 mice represent a model for dissection of how altered DA signaling perturbs circuits that normally balance habitual and goal-directed behaviors.

neuroscience↗

bioRxiv2021

Sex and Circuit Specific Dopamine Transporter Regulation Underlies Unique Behavioral Trajectories of Functional SLC6A3 Coding Variation

Virtually all neuropsychiatric disorders display sex differences in prevalence, age of onset, and/or clinical symptomology. In sex-biased disorders, one sex is often suggested to harbor protective mechanisms, rendering them resilient to genetic and/or environmental risk factors. Here, we demonstrate sex-biased molecular, pharmacological and behavioral effects induced by the dopamine (DA) transporter (DAT) coding variant Ala559Val, previously identified in subjects diagnosed with the male-biased disorders attention-deficit/hyperactivity disorder and autism spectrum spectrum disorder. In DAT Val559 mice, we identified sex differences in response to psychostimulants, social behavior, and cognitive traits. We reveal a sex by circuit dissociation in D2-type autoreceptor (D2AR) regulation of DAT wherein D2AR-dependent DAT phosphorylation and trafficking, detectable in the male dorsal striatum, does not occur in females but rather is a property of the ventral striatum, predicting sex-specific changes in behavior. Consequently, we found that a subset of altered behaviors can be normalized using the D2R antagonist sulpiride in DAT Val559 mice. Our studies provide a cogent example of how sex shapes the behavioral trajectory of DA signaling perturbations and identify the sex-dependent, locality-selective capacity for D2AR regulation of DAT as an unrecognized determinant of this trajectory. Rather than identifying one sex as resilient, we find that sex can drive alterative behavioral patterns from shared signaling perturbations that may result in females being underreported. Our work underscores the utility of model systems to study the functional intrusions of rare genetic variation to gain insights into pathways underlying normal and perturbed trait domains associated with common neuropsychiatric conditions.

neuroscience↗

bioRxiv2021

Disrupted choline clearance and sustained acetylcholine release in vivo by a common choline transporter coding variant associated with poor attentional control in humans

Transport of choline via the neuronal high-affinity choline transporter (CHT; SLC5A7) is essential for cholinergic terminals to synthesize and release acetylcholine (ACh). In humans, we previously demonstrated an association between a common CHT coding substitution (rs1013940; Ile89Val) and reduced attentional control as well as attenuated frontal cortex activation. Here, we used a CRISPR/Cas9 approach to generate mice expressing the I89V substitution and assessed, in vivo, CHT-mediated choline transport, and ACh release. Relative to wild type (WT) mice, CHT-mediated clearance of choline in mice expressing one or two Val89 alleles was reduced by over 80% cortex and by over 50% in striatum. Choline clearance in CHT Val89 mice was further reduced by neuronal inactivation. Deficits in ACh release, 5 and 10 min after repeated depolarization at a low, behaviorally relevant frequency, support an attenuated reloading capacity of cholinergic neurons in mutant mice. The density of CHTs in total synaptosomal lysates and neuronal plasma-membrane-enriched fractions was not impacted by the Val89 variant, indicating a selective impact on CHT function. When challenged with a visual disruptor to reveal attentional control mechanisms, Val89 mice failed to adopt a more conservative response bias. Structural modeling revealed that Val89 may attenuate choline transport by altering conformational changes of CHT that support normal transport rates. Our findings support the view that diminished, sustained cholinergic signaling capacity underlies perturbed attentional performance in individuals expressing CHT Val89. The CHT Val89 mouse serves as a valuable model to study heritable risk for cognitive disorders arising from cholinergic dysfunction. Significance StatementAcetylcholine (ACh) signaling depends on the functional capacity of the neuronal choline transporter (CHT). Previous research demonstrated that humans expressing the common CHT coding variant Val89 exhibit attentional vulnerabilities and attenuated fronto-cortical activation during attention. Here, we find that mice engineered to express the Val89 variant exhibit reduced CHT-mediated choline clearance and a diminished capacity to sustain ACh release. Additionally, Val89 mice lack cognitive flexibility in response to an attentional challenge. These findings provide a mechanistic and cognitive framework for interpreting the attentional phenotype associated with the human Val89 variant and establish a model that permits a more invasive interrogation of CNS effects as well as the development of therapeutic strategies for those, including Val89 carriers, with presynaptic cholinergic perturbations.

neuroscience↗