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Lysophosphatidic acid signaling restores mislocalization of brush border proteins in MYO5B deficient mice
Author(s) -
Kaji Izumi,
Roland Joseph TE,
Engevik Amy C,
Goldstein Anna E,
Dudeja Pradeep K,
Goldenring James R
Publication year - 2019
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.2019.33.1_supplement.869.3
Subject(s) - brush border , villin , lysophosphatidic acid , small intestine , microvillus , ileum , endocrinology , alkaline phosphatase , medicine , multidrug resistance associated protein 2 , apical membrane , biology , chemistry , microbiology and biotechnology , receptor , biochemistry , transporter , atp binding cassette transporter , actin , enzyme , vesicle , membrane , gene
Background & Aim Myosin Vb (MYO5B) is an essential trafficking protein for membrane protein recycling in gastrointestinal (GI) epithelial cells and its mutation causes the congenital diarrheal disease, microvillus inclusion disease (MVID). Our group has reported that MYO5B loss results in a decrease in the brush border localization of nutrient transporters and enzymes, but CFTR expression is maintained, causing malabsorption and secretory diarrhea in MVID patients and MYO5B KO mice. Activation of lysophosphatidic acid (LPA) receptors (LPA 2 and LPA 5 ) can inhibit CFTR and activate NHE3 in the intestinal epithelium. This study tested whether LPA treatment reverses the functional expression of apical proteins in MYO5B knockout (KO) mice. Methods Adult tamoxifen‐induced, intestine‐specific, MYOB KO mice ( VilCre ERT2 ; Myo5b flox/flox ) and littermate control mice were treated with LPA (18:1 at 1 or 3 mg/kg/day) or vehicle, orally or intraperitoneally for 4 days after a single injection of tamoxifen (2 mg/mouse, i.p.). Apical transporter activities in jejunum and ileum were measured by an Üssing chamber system and the localization of apical proteins were evaluated immunostaining with whole‐slide imaging and digital image analysis. Results Following tamoxifen injection, F‐actin‐positive inclusions appeared in the upper small intestine of VilCre ERT2 ; Myo5b flox/flox mice and the brush border localization of phospho‐ezrin, SGLT1, NHE3, DRA, PEPT1, alkaline phosphatase, and DPPIV were lost throughout the intestine. Treatment with LPA partially restored apical localization of phospho‐ezrin, SGLT1, NHE3, alkaline phosphatase, and DPPIV particularly in villus epithelial cells. Consistent with these observations, SGLT1‐dependent short‐circuit current ( I sc ) was 3 times higher in LPA (3 mg/kg)‐treated jejunum and ileum than that of vehicle‐treated VilCre ERT2 ; Myo5b flox/flox mice. LPA dose‐dependently decreased CFTR‐dependent I sc in the steady state, but had no effect on CFTR dependence in carbachol‐ and forskolin‐stimulated I sc , which was increased by MYO5B loss. Conclusions These results suggest that LPA signaling may modulate a MYO5B‐independent trafficking mechanism for some brush border proteins in the small intestine, demonstrating a therapeutic potential for LPA in the treatment of MVID. Support or Funding Information Supported by The Christine Volpe Foundation This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal .