Biology subjects

Reid, M. S.

Publications and source records attributed to Reid, M. S..

4 recordsLinked to original sources

bioRxiv2025

Structural basis for proton inhibition of the two-pore domain K+ channel TASK-1

TASK-1 is a pH-sensitive two-pore domain K+ channel inhibited by external protons. TASK-1 is widely expressed, including in cardiomyocytes and chemosensitive neurons in the brain. Altered channel expression and activity are implicated in diseases including atrial fibrillation, pulmonary arterial hypertension, and developmental delay with sleep apnea. Structures of TASK-1 have been captured with an open external and closed internal gate. The structural basis for external proton inhibition and potential for communication between inner and outer gates are incompletely understood. Here, we determine a cryo-EM structure of TASK-1 at low pH with a closed extracellular gate and assess pH sensitivity of mutated channels. Proton inhibition of TASK-1 involves a C-type selectivity filter gate similar to TASK-3, but distinct from other proton-inhibited K2Ps TASK-2 and TWIK-1. Protonation of an extracellular histidine leads to formation of a hydrophobic seal above the selectivity filter and dilation of the outer two K+ coordination sites to close the channel pore. We find that a pulmonary arterial hypertension-associated loss-of-function mutation near the outer gate increases proton sensitivity, while gain-of-function mutations near the inner X-gate and intracellular cavity reduce proton sensitivity. These data reveal the structural basis for extracellular pH-gating of TASK-1, suggest allosteric communication between the inner and outer gates, and illustrate differences in C-type gating among related K+ channels.

biophysics↗

bioRxiv2019

Cryo-EM structure of the potassium-chloride cotransporter KCC4 in lipid nanodiscs

Cation-chloride-cotransporters (CCCs) catalyze transport of Cl- with K+ and/or Na+ across cellular membranes. CCCs play roles in volume regulation, neural development and function, audition, blood pressure regulation, and renal function. CCCs are targets of drugs including loop diuretics and their disruption is implicated in pathophysiologies including epilepsy, hearing loss, and the genetic disorders Andermann, Gitelman, and Bartter syndromes. Here we present the cryo-EM structure of a CCC, the Mus musculus K+-Cl- cotransporter KCC4, in lipid nanodiscs. The structure, captured in an inside-open conformation, reveals the architecture of KCCs including an extracellular domain poised to regulate transport activity through an outer gate. We further identify substrate K+ and Cl- binding sites and provide a structural explanation for differences in substrate specificity and transport ratio between CCCs. These results provide mechanistic insight into the function and regulation of a physiologically important transporter family.

biophysics↗

bioRxiv2019

Single cell profiling of the VMH reveals a sexually dimorphic regulatory node of energy expenditure

Estrogen signaling in the central nervous system promotes weight loss by increasing thermogenesis and physical activity in the ventromedial hypothalamus (VMH), but the precise neuronal populations regulating these aspects of energy expenditure remain unclear. Here we define the molecular and functional heterogeneity of the VMH using single cell RNA sequencing, in situ hybridization, chemogenetic activation, and targeted gene knockdown. We describe six molecularly distinct neuron clusters in the VMH. In females, estrogen receptor alpha (ER) is restricted to neurons expressing tachykinin-1 (Tac1) or reprimo (Rprm). Further, Tac1 and Rprm expression is enriched in females, a sex difference that is established by permanent effects of gonadal hormones early in life. Finally, while Tac1 ablation selectively impairs movement, here we show that silencing Rprm selectively dysregulates temperature without affecting physical activity. Together this work provides a novel architectural framework whereby distinct and sexually differentiated neuron populations within the VMH mediate sex-specific aspects of metabolic homeostasis.

neuroscience↗

bioRxiv2018

Estrogen Signaling in Arcuate Kiss1 Neurons Suppresses a Sex-Dependent Circuit That Promotes Dense Strong Bones in Female Mice

Central estrogen signaling coordinates energy expenditure, reproduction, and in concert with peripheral estrogen impacts skeletal homeostasis in female rodents. Here, we ablate estrogen receptor alpha (ER) in the medial basal hypothalamus and find a robust bone phenotype only in female mice that results in exceptionally strong trabecular and cortical bones, whose density surpasses other reported mouse models. Stereotaxic guided deletion of ER in the arcuate nucleus increases bone mass in both intact and estrogen-depleted females, confirming the central role of estrogen signaling in this sex-dependent bone phenotype. Loss of ER activity in kisspeptin (Kiss1)-expressing cells is sufficient to recapitulate the bone phenotype, identifying Kiss1 neurons as a critical node in this powerful neuroskeletal circuit. We propose that this newly identified female brain-to-bone pathway exists as a homeostatic regulator to divert calcium and energy stores from bone building when energetic demands are high. Our work reveals a previously unknown target for the treatment of age-related bone disease.

physiology↗