Biology subjects

Patel, S. D.

Publications and source records attributed to Patel, S. D..

4 recordsLinked to original sources

bioRxiv2025

Enteroendocrine Cells Regulate Intestinal Barrier Permeability

The intestinal epithelial barrier is essential for nutrient absorption and protection against ingested pathogens and foreign substances. Barrier integrity is maintained by tight junctions which are sensitive to inflammatory signals, thus creating a feed-forward loop with an increasingly permeable barrier that further drives inflammation and is the hallmark of inflammatory bowel disease. There are currently no therapeutic strategies to improve the intestinal epithelial barrier. We hypothesized that enteroendocrine cells may play an unappreciated role in maintaining barrier integrity. To test this hypothesis, we seeded human intestinal enteroids with genetic loss of enteroendocrine cells on Transwell filters and evaluated transepithelial electrical resistance, paracellular permeability, and the localization and abundance of junctional proteins. We found that enteroendocrine cells were required to maintain a healthy barrier in crypt-like "stem" and villus-like differentiated cultures. Additionally, exogenous supplementation of enteroendocrine-deficient cultures with the hormones peptide tyrosine tyrosine (PYY) and the somatostatin analog octreotide was sufficient to rescue many aspects of this barrier defect both at baseline and in the presence of the inflammatory cytokine tumor necrosis factor (TNF). Surprisingly, these improvements in barrier function occurred largely independently of changes in protein abundance of junctional proteins zona-occludens 1, occludin, and claudin-2. These findings support a novel role for enteroendocrine cells in augmenting epithelial barrier function in the presence of inflammatory stimuli and present an opportunity for developing therapies to improve the intestinal barrier. NEW & NOTEWORTHYThere are no therapies that directly improve the permeability of the intestinal epithelial barrier. This work uses a human intestinal epithelial model system to demonstrate that sensory enteroendocrine cells are necessary for healthy barrier function and that two of their secreted products, peptide YY and somatostatin, are sufficient to improve barrier function at homeostasis and in the presence of inflammatory cytokines. This could provide novel treatments for strengthening the epithelial barrier in human gastrointestinal disease.

physiology↗

bioRxiv2021

Opioid withdrawal abruptly disrupts amygdala circuit function by reducing peptide actions

Opioid withdrawal drives relapse and contributes to compulsive drug use through disruption of endogenous opioid dependent learning circuits in the amygdala. Normally, endogenous opioids control these circuits by inhibiting glutamate release from basolateral amygdala principal neurons onto GABAergic intercalated cells. Using patch-clamp electrophysiology in rat brain slices, we reveal that opioid withdrawal dials down this endogenous opioid inhibition of synaptic transmission. Peptide activity is dialled down due to a protein kinase A dependent increase in the activity of the peptidase, neprilysin. This disrupts peptidergic control of both GABAergic and glutamatergic transmission through multiple amygdala circuits, including reward-related outputs to the nucleus accumbens. This likely disrupts peptide-dependent learning processes in the amygdala during withdrawal. and may direct behaviour towards compulsive drug use. Restoration of endogenous peptide activity during withdrawal may be a viable option to normalise synaptic transmission in the amygdala and restore normal reward learning. In BriefWe find that opioid withdrawal dials down inhibitory neuropeptide activity in the amygdala. This disrupts both GABAergic and glutamatergic transmission through amygdala circuits, including reward-related outputs to the nucleus accumbens. This likely disrupts peptide-dependent learning processes in the amygdala during withdrawal and may direct behaviour towards compulsive drug use. HighlightsO_LIDuring opioid withdrawal, peptidase activity is upregulated in an amygdala circuit C_LIO_LIPeptidase upregulation occurs via a PKA-dependent mechanism C_LIO_LIIncreased peptidase activity limits peptidergic control of synaptic transmission C_LIO_LIOpioid withdrawal disrupts the balance of excitation and inhibition in the amygdala C_LI

neuroscience↗

bioRxiv2021

The anterior Hox gene ceh-13 and elt-1/GATA activate the posterior Hox genes nob-1 and php-3 to specify posterior lineages in the C. elegans embryo

Hox transcription factors play a conserved role in specifying positional identity during animal development, with posterior Hox genes typically repressing the expression of more anterior Hox genes. Here, we dissect the regulation of the posterior Hox genes nob-1 and php-3 in the nematode C. elegans. We show that nob-1 and php-3 are co-expressed in gastrulation-stage embryos in cells that previously expressed the anterior Hox gene ceh-13. This expression is controlled by several partially redundant transcriptional enhancers. These enhancers require ceh-13 for expression, providing a striking example of an anterior Hox gene positively regulating a posterior Hox gene. Several other regulators also act positively through nob-1/php-3 enhancers, including elt-1/GATA, ceh-20/ceh-40/Pbx, unc-62/Meis, pop-1/TCF, ceh-36/Otx and unc-30/Pitx. We identified defects in both cell position and cell division patterns in ceh-13 and nob-1;php-3 mutants, suggesting that these factors regulate lineage identity in addition to positional identity. Together, our results highlight the complexity and flexibility of Hox gene regulation and function and the ability of developmental transcription factors to regulate different targets in different stages of development. Author SummaryHox genes are critical for head-to-tail patterning during embryonic development in all animals. Here we examine the factors that are necessary to turn on two posterior Hox genes, nob-1 and php-3, in the nematode worm, C. elegans. We identified six new transcription factors and three enhancer regions of DNA that can activate expression of nob-1/php-3. Unexpectedly, these activating transcription factors included ceh-13, an anterior Hox gene, and elt-1, a regulator of skin development that is briefly expressed in many cells that do not adopt skin fates, including the cells that express nob-1. Furthermore, the cellular defects we observed in ceh-13 and nob- 1;php-3 mutant embryos indicate that the early embryonic functions of these Hox genes help determine the identity of cells as well as their position within the embryo. Our findings identify new roles for Hox genes in C. elegans and emphasize the ability of transcription factors to contribute to the diversification of cell types and the adoption of specific cell types at different phases of embryonic development.

genetics↗

bioRxiv2020

Erythrocyte CD55 mediates the internalization of Plasmodium falciparum parasites

Invasion of human erythrocytes by the malaria parasite Plasmodium falciparum is a multi-step process. Previously, a forward genetic screen for P. falciparum host factors identified erythrocyte CD55 as essential for invasion, but its specific role and how it interfaces with the other factors that mediate this complex process are unknown. Using CRISPR-Cas9 editing, antibody-based inhibition, and live cell imaging, here we show that CD55 is specifically required for parasite internalization. Pre-invasion kinetics, erythrocyte deformability, and echinocytosis were not influenced by CD55, but entry was inhibited when CD55 was blocked or absent. Visualization of parasites attached to CD55-null erythrocytes point to a role for CD55 in progression of the moving junction. Our findings demonstrate that CD55 acts after discharge of the parasites rhoptry organelles, and plays a unique role relative to all other invasion receptors. As the requirement for CD55 is strain-transcendent, these results suggest that CD55 or its interacting partners may hold potential as therapeutic targets for malaria.

microbiology↗