Biology subjects

Bok, D.

Publications and source records attributed to Bok, D..

4 recordsLinked to original sources

bioRxiv2026

The 3D Ultrastructure of C. elegans Gut Granules

We identify an endoderm-restricted organelle in published volume electron microscopy datasets of C. elegans embryos. The organelle consists of a tubular ring surrounding a membrane-bound compartment harboring a prominent dense particle and exhibits a basal polarity and size concordant with canonical gut granules. This finding offers ultrastructural detail to recent evidence that gut granules are bi-lobed organelles with two distinct compartments.

cell biology↗

bioRxiv2025

Characterization and targeting of the endosomal signaling of the gastrin releasing peptide receptor in pruritus.

Chronic pruritus is a major unmet clinical problem affecting one in four adults. G protein-coupled receptors (GPCRs) are key receptors driving itch signaling and are a therapeutic target for itch relief. The endosomal signaling of GPCRs provides new challenges for understanding how GPCR signaling is regulated, how endosomal signaling of GPCRs contributes to disease states like chronic pruritus and opens new targets for therapeutic development. The Gastrin releasing peptide receptor (GRPR) is a key mediator of pruritus in the spinal cord. Yet, little is known about the molecular mechanisms regulating GRPR signaling in pruritus, if GRPR can signal from endosomes, or the role of endosomal GRPR in the development of pruritus. Here we show the importance of internalization and endosomal signaling of GRPR in pruritus. Agonist induced GRPR internalization and trafficking was quantified using BRET or microscopy while endosomal-mediated ERK signaling was measured using compartmentalized FRET biosensors. Recruitment of G proteins to endosomes was measured with NanoBit BRET. pH sensitive mesoporous silica nanoparticles (MSN) which accumulated in endosomes were used to deliver RC-3095, a GRPR specific antagonist, intracellularly to block endosomal signaling of GRPR. MSN-RC proved more effective than free RC-3095 at inhibiting chloroquine scratching in mice. Our results demonstrate a critical role for GRPR endosomal signaling in itch sensation. These results highlight the ability of endosomally targeted antagonist to inhibit GRPR signaling and provide a new target for developing therapeutics that block GRPR mediated pruritus. Significance StatementGPCRs are dynamic signaling receptors that can continue to signal following internalization and trafficking to endosomes. Using subcellular targeted BRET and FRET based biosensors we can quantify the recruitment of signaling partners like G proteins and arrestins to GRPR from the endosomal compartment. Inhibition of clathrin and dynamin mediated endocytosis allowed to differentiate plasma membrane vs endosomal signaling of GRPR. pH sensitive nanoparticles loaded with the GRPR antagonist RC-3095 are endocytosed to the endosomal network where they specifically target and block endosomal GRPR signaling. Intrathecal injection of RC-3095 loaded nanoparticles blocked chloroquine induced scratching behavior in mice. Thus, intracellular GRPR drives itch sensation and targeted inhibition of intracellular GRPR signaling is a more effective strategy to treat pruritus.

neuroscience↗

bioRxiv2021

CNTF enhances aerobic glycolysis and anabolic activities in degenerating retinas

Ciliary neurotrophic factor (CNTF) acts as a potent neuroprotective cytokine in multiple models of retinal degeneration. To understand mechanisms underlying its broad neuroprotective effects, we have investigated the influence of CNTF on metabolism in a mouse model of photoreceptor degeneration. CNTF treatment improves the morphology of photoreceptor mitochondria, but also leads to reduced oxygen consumption and suppressed respiratory chain activities. Molecular analyses show elevated glycolytic pathway gene transcripts and active enzymes. Metabolomics analyses detect significantly higher levels of ATP and the energy currency phosphocreatine, elevated glycolytic pathway metabolites, increased TCA cycle metabolites, lipid biosynthetic pathway intermediates, nucleotides, and amino acids. Moreover, CNTF treatment restores the key antioxidant glutathione to the wild type level. Therefore, CNTF significantly impacts the metabolic status of degenerating retinas by promoting aerobic glycolysis and augmenting anabolic activities. These findings reveal cellular mechanisms underlying enhanced neuronal viability and suggest potential therapies for treating retinal degeneration.

neuroscience↗

bioRxiv2018

Ocular disease mechanisms elucidated by genetics of human fetal retinal pigment epithelium gene expression

The eye is an intricate organ with limited representation in large-scale functional genomics datasets. The retinal pigment epithelium (RPE) serves vital roles in ocular development and retinal homeostasis. We interrogated the genetics of gene expression of cultured human fetal RPE (fRPE) cells under two metabolic conditions. Genes with disproportionately high fRPE expression are enriched for genes related to inherited ocular diseases. Variants near these fRPE-selective genes explain a larger fraction of risk for both age-related macular degeneration (AMD) and myopia than variants near genes enriched in 53 other human tissues. Increased mitochondrial oxidation of glutamine by fRPE promoted expression of lipid synthesis genes implicated in AMD. Expression and splice quantitative trait loci (e/sQTL) analysis revealed shared and metabolic condition-specific loci of each type and several eQTL not previously described in any tissue. Fine mapping of fRPE e/sQTL across AMD and myopia genome-wide association data suggests new candidate genes, and mechanisms by which the same common variant of RDH5 contributes to both increased AMD risk and decreased myopia risk. Our study highlights the unique transcriptomic characteristics of fRPE and provides a resource to connect e/sQTL in a critical ocular cell type to monogenic and complex eye disorders.

genomics↗