Biology subjects

Reynolds, E.

Publications and source records attributed to Reynolds, E..

5 recordsLinked to original sources

bioRxiv2023

Human Surfactant Protein A Alleviates SARS-CoV-2 Infectivity in Human Lung Epithelial Cells

SARS coronavirus 2 (SARS-CoV-2) infects human angiotensin-converting enzyme 2 (hACE2)-expressing lung epithelial cells through its spike (S) protein. The S protein is highly glycosylated and could be a target for lectins. Surfactant protein A (SP-A) is a collagen-containing C-type lectin, expressed by mucosal epithelial cells and mediates its antiviral activities by binding to viral glycoproteins. This study examined the mechanistic role of human SP-A in SARS-CoV-2 infectivity. The interactions between human SP-A and SARS-CoV-2 S protein and hACE2 receptor, and SP-A level in COVID-19 patients were assessed by ELISA. The effect of SP-A on SARS-CoV-2 infectivity was analyzed by infecting human lung epithelial cells (A549-ACE2) with pseudoviral particles and infectious SARS-CoV-2 (Delta variant) pre-incubated with SP-A. Virus binding, entry, and infectivity were assessed by RT-qPCR, immunoblotting, and plaque assay. The results showed that human SP-A can bind SARS-CoV-2 S protein/RBD and hACE2 in a dose-dependent manner (p<0.01). Human SP-A inhibited virus binding and entry, and reduce viral load in lung epithelial cells, evidenced by the dose-dependent decrease in viral RNA, nucleocapsid protein, and titer (p<0.01). Increased SP-A level was observed in the saliva of COVID-19 patients compared to healthy controls (p<0.05), but severe COVID-19 patients had relatively lower SP-A levels than moderate COVID-19 patients (p<0.05). Therefore, SP-A plays an important role in mucosal innate immunity against SARS-CoV-2 infectivity by directly binding to the S protein and inhibiting its infectivity in host cells. SP-A level in the saliva of COVID-19 patients might serve as a biomarker for COVID-19 severity.

molecular biology↗

bioRxiv2023

Bsc2 is a novel regulator of triglyceride lipolysis that demarcates a lipid droplet subpopulation

Cells store lipids in the form of triglyceride (TG) and sterol-ester (SE) in lipid droplets (LDs). Distinct pools of LDs exist, but a pervasive question is how proteins localize to and convey functions to LD subsets. Here, we show the yeast protein YDR275W/Tld1 (for TG-associated LD protein 1) localizes to a subset of TG-containing LDs, and reveal it negatively regulates lipolysis. Mechanistically, Tld1 LD targeting requires TG, and is mediated by two distinct hydrophobic regions (HRs). Molecular dynamics simulations reveal Tld1s HRs interact with TG on LDs and adopt specific conformations on TG-rich LDs versus SE-rich LDs in yeast and human cells. Tld1-deficient yeast display no defect in LD biogenesis, but exhibit elevated TG lipolysis dependent on lipase Tgl3. Remarkably, over-expression of Tld1, but not LD protein Pln1/Pet10, promotes TG accumulation without altering SE pools. Finally, we find Tld1-deficient cells display altered LD mobilization during extended yeast starvation. We propose Tld1 senses TG-rich LDs and regulates lipolysis on LD subpopulations.

cell biology↗

bioRxiv2022

Incilius alvarius cell-based synthesis of 5-MeO-DMT

There is growing interest in the therapeutic potential of 5-MeO-DMT (5-methoxy-N,N-dimethyltryptamine) for psychiatric disorders. While 5-MeO-DMT can be chemically synthesized, the parotoid gland secretions of Incilius alvarius (also known as the Colorado River or Sonoran Desert toad) contain 5-MeO-DMT and other molecules including bufotenine, bufagenins, bufotoxins, and indole alkylamines that may have individual clinical utility or act as entourage molecules to enhance the activity of 5-MeO-DMT. Incilius alvarius is currently under severe ecological pressure due to demand for natural 5-MeO-DMT and habitat loss. We established a cell line from tissue obtained by wedge biopsy of the Incilius alvarius parotoid gland and confirmed the cell-based biosynthesis of 5-MeO-DMT by LC-MS/MS. Cell-based biosynthesis of Incilius alvarius parotoid gland secretions is a potentially cruelty-free and sustainable source of naturally derived 5-MeO-DMT for research and drug development. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=88 SRC="FIGDIR/small/492789v3_ufig1.gif" ALT="Figure 1"> View larger version (23K): org.highwire.dtl.DTLVardef@163bfc6org.highwire.dtl.DTLVardef@1c36601org.highwire.dtl.DTLVardef@15ded62org.highwire.dtl.DTLVardef@18bbea8_HPS_FORMAT_FIGEXP M_FIG C_FIG

pharmacology and toxicology↗

bioRxiv2022

Triglyceride lipolysis driven by glucose restriction triggers liquid-crystalline phase transitions and proteome remodeling of lipid droplets

Lipid droplets (LDs) are reservoirs for triglycerides (TGs) and sterol-esters (SEs), but how these lipids are organized within LDs and influence its proteome remains unclear. Using in situ cryoelectron tomography, we show that glucose restriction triggers lipid phase transitions within LDs generating liquid-crystalline lattices inside them. Mechanistically this requires TG lipolysis, which decreases the LD TG:SE ratio, promoting SE transition to a liquid-crystalline phase. Molecular dynamics simulations reveal TG depletion promotes spontaneous TG and SE de-mixing in LDs, additionally altering the lipid packing of the phospholipid monolayer surface. Fluorescence imaging and proteomics further reveal that liquid-crystalline phases are associated with selective remodeling of the LD proteome. Some canonical LD proteins including Erg6 re-localize to the ER network, whereas others remain LD-associated. Model peptide LiveDrop also redistributes from LDs to the ER, suggesting liquid-crystalline-phases influence ER-LD inter organelle transport. Our data suggests glucose restriction drives TG mobilization, which alters the phase properties of LD lipids and selectively remodels the LD proteome.

cell biology↗

bioRxiv2021

Postsynaptic plasticity of cholinergic synapses underlies the induction and expression of appetitive memories in Drosophila

In vertebrates, several forms of memory-relevant synaptic plasticity involve postsynaptic rearrangements of glutamate receptors. In contrast, previous work indicates that Drosophila and other invertebrates store memories using presynaptic plasticity of cholinergic synapses. Here, we provide evidence for postsynaptic plasticity at cholinergic output synapses from the Drosophila mushroom bodies (MBs). We find that the nicotinic acetylcholine receptor (nAChR) subunit 5 is required within specific MB output neurons (MBONs) for appetitive memory induction, but is dispensable for aversive memories. In addition, nAChR 2 subunits mediate memory expression and likely functions downstream of 5 and the postsynaptic scaffold protein Dlg. We show that postsynaptic plasticity traces can be induced independently of the presynapse, and that in vivo dynamics of 2 nAChR subunits are changed both in the context of associative and non-associative memory formation, underlying different plasticity rules. Therefore, regardless of neurotransmitter identity, key principles of postsynaptic plasticity support memory storage across phyla.

neuroscience↗