Cell differentiation is disrupted by MYO5B loss through Wnt/Notch imbalance.

Izumi Kaji,Sudiksha Rathan-Kumar,Masahiko Watanabe,Joseph T Roland,James R Goldenring,Andreanna Burman,Anna E Goldstein,Amy C Engevik

doi:10.1172/jci.insight.150416

Izumi Kaji, Sudiksha Rathan-Kumar + Show 6 more

Open Access

https://doi.org/10.1172/jci.insight.150416

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Abstract

Functional loss of myosin Vb (MYO5B) induces a variety of deficits in intestinal epithelial cell function and causes a congenital diarrheal disorder, microvillus inclusion disease (MVID). The impact of MYO5B loss on differentiated cell lineage choice has not been investigated. We quantified the populations of differentiated epithelial cells in tamoxifen-induced, epithelial cell–specific MYO5B-knockout (VilCreERT2 Myo5bfl/fl) mice utilizing digital image analysis. Consistent with our RNA-sequencing data, MYO5B loss induced a reduction in tuft cells in vivo and in organoid cultures. Paneth cells were significantly increased by MYO5B deficiency along with expansion of the progenitor cell zone. We further investigated the effect of lysophosphatidic acid (LPA) signaling on epithelial cell differentiation. Intraperitoneal LPA significantly increased tuft cell populations in both control and MYO5B-knockout mice. Transcripts for Wnt ligands were significantly downregulated by MYO5B loss in intestinal epithelial cells, whereas Notch signaling molecules were unchanged. Additionally, treatment with the Notch inhibitor dibenzazepine (DBZ) restored the populations of secretory cells, suggesting that the Notch pathway is maintained in MYO5B-deficient intestine. MYO5B loss likely impairs progenitor cell differentiation in the small intestine in vivo and in vitro, partially mediated by Wnt/Notch imbalance. Notch inhibition and/or LPA treatment may represent an effective therapeutic approach for treatment of MVID.

Highlights

Myosin Vb (MYO5B) is an essential motor protein for apical membrane protein trafficking, and its inhibition through truncation or missense mutations causes the congenital diarrheal disorder microvillus inclusion disease (MVID) [1, 2]
The frequency of DCLK1+ cells was 80% lower in MYO5B-deficient intestine than control, in the crypts, indicating that tuft cell differentiation was inhibited by MYO5B loss (Figure 1B)
We quantified the frequency of differentiated secretory cells in tamoxifen-induced MYO5B-knockout mouse intestine to investigate the impact of MYO5B loss on epithelial cell lineage choice

Summary

Introduction

Myosin Vb (MYO5B) is an essential motor protein for apical membrane protein trafficking, and its inhibition through truncation or missense mutations causes the congenital diarrheal disorder microvillus inclusion disease (MVID) [1, 2]. We reported that tamoxifen-induced, intestinespecific MYO5B deficiency in VilCreERT2 Myo5bfl/fl mice demonstrates hyperproliferation and villus blunting. Treatment of VilCreERT2 Myo5bfl/fl mice with a bioactive phospholipid, lysophosphatidic acid (LPA), partially restored the villus structure, brush border height, and apical localization of nutrient transporters in the small intestine [7]. Based on these observations, we hypothesized that MYO5B loss causes differentiation deficits in intestinal epithelial cells and that LPA supplementation may promote epithelial differentiation and microvillus maturation. The function of MYO5B and LPA signaling in differentiation of rare epithelial cell populations, has not been investigated

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