Biology subjects

Duarte, Y.

Publications and source records attributed to Duarte, Y..

3 recordsLinked to original sources

bioRxiv2025

The BK channel-NS1619 agonist complex reveals molecular insights on allosteric activation gating

BK channels play essential roles in a wealth of physiological functions, including regulating smooth muscle tone and neurotransmitter release. Its dysfunction, often caused by loss-of-function mutations, can lead to severe phenotypes, including ataxia and sensory impairment. Despite the therapeutic potential of BK channel agonists, the molecular mechanisms by which they stabilize the pores open conformation remain unclear. Using cryo-electron microscopy and molecular dynamic simulations, we identified that NS1619, a synthetic benzimidazolone agonist, first described as a BK opener, binds within a pocket formed by the S6/RCK1 linker and the S4 transmembrane segment. Agonist binding drives a twisting motion in the S6 segment, enabling critical interactions with residues K330, K331, and F223. Our findings clarify the mechanism of NS1619 and suggest that its binding site can accommodate other agonists, highlighting a promising target for therapeutic development. TeaserBK channel activation by NS1619 reveals key binding interactions, offering insights for designing targeted therapeutic agents.

biophysics↗

bioRxiv2024

Oral Boldine Administration Attenuates Glia Activation and Prevents Neuropathic Pain in a Murine Spared Nerve Injury Model

BackgroundChronic pain is present in about 20% of the population and is a major burden to the health care system. About 30-40% of these patients report neuropathic pain. Neuropathic pain is defined as pain caused by injury or disease of the somatosensory nervous system. Current available treatments for neuropathic pain have limited efficacy and substantial side effects. MethodsTo address the need for more effective and safer treatments for neuropathic pain, this study aimed to test whether boldine, a naturally occurring alkaloid, could attenuate neuropathic pain in a murine model of spared nerve injury (SNI). Von Frey filament test, hot/cold plate test and dynamic weight bearing test were used to assess pain phenotypes following SNI. ResultsWe found that boldine inhibited the lipopolysaccharide-induced overexpression of inflammatory markers in BV-2 microglial cells. Oral administration of boldine at 50 mg/kg body weight/day resulted in significant reduction of SNI-induced mechanical and thermal hypersensitivity. Boldine also corrected SNI-induced weight bearing deficits, which are an indication of spontaneous pain. Boldine significantly inhibited SNI-induced peripheral inflammation as indicated by reduced levels of inflammatory cytokines/chemokines in the serum. Immunofluorescence studies revealed that boldine reduced the number of reactive astrocytes and inhibited microglia activation in lumbar spinal cord. ConclusionOur findings suggest that boldine may be a promising therapeutic candidate for the treatment of neuropathic pain, possibly through inhibition of glia activation and neuroinflammation.

neuroscience↗

bioRxiv2020

Analysis of SARS-CoV-2 ORF3a structure reveals chloride binding sites

SARS-CoV-2 ORF3a is believed to form ion channels, which may be involved in the modulation of virus release, and has been implicated in various cellular processes like the up-regulation of fibrinogen expression in lung epithelial cells, downregulation of type 1 interferon receptor, caspase-dependent apoptosis, and increasing IFNAR1 ubiquitination. ORF3a assemblies as homotetramers, which are stabilized by residue C133. A recent cryoEM structure of a homodimeric complex of ORF3a has been released. A lower-resolution cryoEM map of the tetramer suggests two dimers form it, arranged side by side. The dimers cryoEM structure revealed that each protomer contains three transmembrane helices arranged in a clockwise configuration forming a six helices transmembrane domain. This domains potential permeation pathway has six constrictions narrowing to about 1 [A] in radius, suggesting the structure solved is in a closed or inactivated state. At the cytosol end, the permeation pathway encounters a large and polar cavity formed by multiple beta strands from both protomers, which opens to the cytosolic milieu. We modeled the tetramer following the arrangement suggested by the low-resolution tetramer cryoEM map. Molecular dynamics simulations of the tetramer embedded in a membrane and solvated with 0.5 M of KCl were performed. Our simulations show the cytosolic cavity is quickly populated by both K+ and Cl-, yet with different dynamics. K+ ions moved relatively free inside the cavity without forming proper coordination sites. In contrast, Cl- ions enter the cavity, and three of them can become stably coordinated near the intracellular entrance of the potential permeation pathway by an inter-subunit network of positively charged amino acids. Consequently, the central cavitys electrostatic potential changed from being entirely positive at the beginning of the simulation to more electronegative at the end.

biophysics↗