LAUSR

Functional loss of a motor protein, Myosin Vb (MYO5B), induces a variety of deficits in intestinal epithelial function and causes a congenital diarrheal disorder, microvillus inclusion disease (MVID). Using the tamoxifen-induced epithelial-specific MYO5B-deficient ( Villin-CreERT2;Myo5bflox/flox) mice and enteroid models, we have reported that MYO5B loss disrupts progenitor cell differentiation probably via Wnt/Notch imbalance and lysophosphatidic acid (LPA) signaling can ameliorate the differentiation. We hypothesize that selective LPA receptor agonists have therapeutic effects on intestinal epithelial cells lacking MYO5B. Adult Villin-CreERT2;Myo5bflox/flox mice received one of the LPAR subtype-specific agonists, UCM-05194 (LPAR1), Compound-1 (LPAR5), GRI977143 (LPAR2), or vehicle once a day for 4 days following a single tamoxifen injection to induce MYO5B loss. Mucosal histology and differentiated cell populations were analyzed by immunostaining. Transcription changes were analyzed by RNA-sequencing of enteroids with or without Compound-1 in the medium. LPAR5 expression was significantly higher than other LPAR subtypes in both control and MYO5B-deficient intestines. Intraperitoneal administration of Compound-1 significantly improved villus/crypt ratio, whereas other agonists did not significantly alter the intestinal histology in the induced Villin-CreERT2;Myo5bflox/flox mice. Nutrient transporters in mature enterocytes, such as NHE3 and SGLT1, were mislocalized from apical membrane in MYO5B-deficient intestine and their localization were partially recovered to the apical membranes by Compound-1 treatment. Compoud-1 also normalized the number of tuft cells and intraepithelial lymphocytes that were significantly reduced by MYO5B loss in the small intestine. RNA-sequencing in the induced MYO5B-deficient mouse enteroids demonstrated significant upregulation of Notch1, Notch2, and Notch3. Consistent with these, treatment of MYO5B-deficient mice with the Notch2-prefered γ secretase inhibitor, Nirogacestat, restored the differentiation of secretory cells, suggesting that the Notch signaling pathway can be a drug candidate for MYO5B-deficient intestine. Although Compound-1 treatment in the mouse enteroids did not alter Notch signaling genes, Compound-1 significantly decreased several inflammation- or cancer-associated genes, such as Nlrp1b, Ldhb, and Trim30a, which were upregulated by MYO5B loss in the enteroid cultures. These observations suggest that MYO5B loss directly upregulates Notch signaling in intestinal epithelial cells and that LPAR5 activation can ameliorate proper cell differentiation independent of Notch pathway in the intestine with inactivating MYO5B. Targeting Notch and LPAR5 may represent effective therapeutic approaches for treatment of MVID. NIH R01DK128190, RC2DK118640 This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.