Biology subjects

Parkos, C. A.

Publications and source records attributed to Parkos, C. A..

4 recordsLinked to original sources

bioRxiv2026

Epithelial and γδ T cell CD47 have complementary yet distinct roles in regulating γδ intraepithelial lymphocyte migration

Intraepithelial lymphocytes expressing the {gamma}{delta} T cell receptor ({gamma}{delta} IEL) continuously survey the intestinal epithelium to promote mucosal host defense. Although {gamma}{delta} IELs migrate in and out of the lateral intercellular space (LIS) between adjacent enterocytes, the molecular mechanisms governing their migratory behavior are incompletely understood. Based on the known role of CD47, or integrin associated protein (IAP), in mediating neutrophil transepithelial migration, we investigated whether CD47 expression reflects a conserved mechanism regulating {gamma}{delta} IEL surveillance behavior. Here, we report that conditional CD47 deletion on intestinal epithelial cells or {gamma}{delta} T cells had no effect on IEL composition. Using intravital imaging, we identified complementary roles for CD47 on {gamma}{delta} IELs and epithelial cells, with epithelial CD47 restricting {gamma}{delta} IEL motility and {gamma}{delta} T-cell-derived CD47 promoting cell migration. Further investigation revealed that both CD47 and CD18 contribute to {gamma}{delta} IEL surveillance behavior, although CD47 regulates {gamma}{delta} IEL migration in a CD18-independent manner.

immunology↗

bioRxiv2026

The Protein Tyrosine Phosphatase CD45 promotes PMN Transepithelial Migration, Antimicrobial Function and Colonic Mucosal Repair

Polymorphonuclear neutrophils (PMNs) serve as frontline defenders against injury and infection, eliminating pathogens and initiating mucosal tissue repair. However, excessive PMN transepithelial migration (TEpM) contributes to chronic mucosal inflammatory disorders, including inflammatory bowel disease. PMN pro-inflammatory and pro-repair functions are regulated by incompletely defined signaling cascades involving kinases and phosphatases. Here, we determined how the protein tyrosine phosphatase CD45/PTPRC regulates PMN trafficking and effector functions in the gut. Pharmacologic inhibition of CD45 significantly reduced PMN colonic TEpM in vitro and in vivo and decreased intestinal PMN trafficking was observed in transgenic mice with PMN-specific deletion of CD45 (MRP8-Cre;Cd45fl/fl). Beyond limiting TEpM, CD45 depletion impaired key antimicrobial functions, including degranulation and phagocytosis, indicating broader effects on PMN effector activity. Importantly, recovery from dextran sodium sulfate (DSS)-induced colitis and biopsy-induced colonic wounding was delayed in MRP8-Cre;Cd45fl/fl mice, linking altered PMN function to defective mucosal healing. Mechanistically, CD45 depletion reduced surface expression of the {beta}2 integrin CD11b/CD18 and inactivated the Src family kinase member Lyn. Together, data highlight a novel CD45-CD11b-Lyn signaling axis that regulates PMN trafficking and effector functions in the intestine and identify CD45 as a promising target for modulating PMN function to promote mucosal tissue repair.

immunology↗

bioRxiv2025

RUNX2 promotes epigenetic WNT signaling in inflamed intestinal epithelial cells

Ulcerative colitis (UC) is characterized by chronic mucosal inflammation, recurrent epithelial injury, and impaired colonic mucosal wound healing. While WNT/{beta}-catenin dysregulation has been reported in UC, the mechanisms of such abnormalities remain unclear. To investigate epithelial intrinsic alterations associated with UC, we performed single-nucleus RNA-seq (snRNA-seq) and ATAC-seq (snATAC-seq) multiomics on human primary colonic epithelial cells (colonoids) from healthy donors and patients with inactive or active UC. Colonoids were cultured in a 3D matrix recapitulating crypt base cells or grown as 2D monolayers in differentiation medium to recapitulate luminal epithelial cells. Colonoids from active UC had a unique cell population with elevated CTNNB1 and reduced APC expression. Chromatin profiling identified enrichment of RUNX2 motifs in this UC-associated cell population. Active UC colonoids exhibited reduced OLFM4 expression in 3D and the differentiation marker VIL1 in 2D, suggesting impaired self-renewal and maturation. RUNX2 inhibition using CADD522 reduced {beta}-catenin levels in 3D colonoids and restored VIL1 expression and junctional {beta}-catenin localization in 2D cultures. These findings reveal an intrinsic defect in epithelial renewal in UC, driven in part by RUNX2-dependent WNT dysregulation. Our study identifies RUNX2 as a transcriptional regulator of epithelial stem cell function and WNT signaling in the inflamed human colon. Graphical Abstract summarySingle-nucleus RNA and ATAC sequencing of UC patient-derived colonoids reveals a RUNX2-associated WNT signature in active inflammation. Elevated {beta}-catenin and reduced OLFM4 and VIL1 expression indicate impaired self-renewal and differentiation. Pharmacologic inhibition of RUNX2 restores epithelial maturation, identifying RUNX2 as a key regulator of epithelial dysfunction in UC. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=134 SRC="FIGDIR/small/688458v1_ufig1.gif" ALT="Figure 1"> View larger version (27K): org.highwire.dtl.DTLVardef@14c0093org.highwire.dtl.DTLVardef@b9b6a3org.highwire.dtl.DTLVardef@858ee2org.highwire.dtl.DTLVardef@67b98c_HPS_FORMAT_FIGEXP M_FIG C_FIG

pathology↗

bioRxiv2025

Crb3 and NF2: A dynamic duo that controls assembly of the apical junctions and barrier function via Rho/ROCK signaling

The gastrointestinal epithelium serves as a critical barrier separating intestinal lumen contents from the underlying tissue environment. Structure and function of the apical junctional complex (AJC), comprising tight and adherens junctions, are essential for establishing and maintaining a polarized and functional epithelial barrier. In this study, we investigated mechanisms by which an apical polarity protein Crumbs homolog 3 (CRB3) regulates AJC assembly and barrier function in primary murine intestinal epithelial cells. Using primary colonic epithelial cells (colonoids) derived from inducible and conditional Crb3 knockdown (Crb3ER{Delta}IEC) and control mice (Crb3fl/fl), we demonstrate that Crb3 loss leads to compromised epithelial barrier function that was associated with hypercontractile perijunctional actomyosin and defective assembly of the AJC. We identified CRB3 associates with the Band 4.1 family of cytoskeletal linker proteins, Merlin (NF2) via FERM (band4.1/ezrin/radixin/moesin) binding domain (FBD) of CRB3. Interestingly, NF2 knockdown in cultured intestinal epithelial cells phenocopied the effect of CRB3 deletion, supporting a coordinated role in AJC formation and barrier assembly. Moreover, increased active Rho was detected in assembling junctions of Crb3-null cells and inhibition of ROCKII and myosin II alleviated the hypercontractile phenotype, highlighting involvement of Rho/ROCK signaling. Additionally, increased vinculin localization at the AJC seen in Crb3-null epithelial cells indicates elevated tension at junctions. Our findings underscore the important role of Crb3 and NF2 in regulating contractility of the perijunctional actomyosin ring, mechanical tension at the AJC and barrier function via Rho/ROCK signaling during junctional assembly in intestinal epithelial cells.

cell biology↗