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HuR Regulates Functions of Paneth Cells in the Intestinal Epithelium by Altering Apical TLR2 Distribution through Control of CNPY3 Expression
Author(s) -
Xiao Lan,
Li Xiaoxue,
Cai Jiazhong,
Chung Hee K.,
Jaladanki Rao N.,
Wang JianYing
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.869.6
Subject(s) - paneth cell , intestinal epithelium , epithelium , crypt , microbiology and biotechnology , intestinal mucosa , biology , homeostasis , ex vivo , transfection , immunology , cell culture , in vivo , small intestine , medicine , endocrinology , genetics
The mammalian intestinal epithelium is a vigorously self‐renewing tissue in the body and its homeostasis and functions depend on a dynamic balance among multiple cell activities. Paneth cells in the gut epithelium are localized at the base of the crypt area and play an important role in the mucosal renewal and defense. Toll‐like receptors (TLRs) regulates Paneth cell functions, but the underlying mechanism remains largely unknown. RNA‐binding protein HuR is highly expressed in the intestinal epithelium and acts as a key biological regulator of mucosal homeostasis by controlling stability and translation of the target mRNAs. Conditional deletion of HuR in intestinal epithelial cells (IECs) inhibits epithelial renewal and delays mucosal healing after acute injury. The current study was to test the hypothesis that HuR regulates Paneth cell functions in the intestinal epithelium via TLRs. Methods Studies were conducted in IEC tissue‐specific HuR knockout (IE‐HuR −/− ) mice, primary intestinal organoids, and IECs (lines of Caco‐2 and IEC‐6). HuR levels in vitro and ex vivo were decreased by transfection with specific siRNA (siHuR) or increased by its gene overexpression. TLR levels were determined by Western blotting analysis and their cellular distribution was examined by immunohistochemistry. Results The HuR‐deficient intestinal epithelium exhibited obvious abnormalities in Paneth cell functions in vivo and ex vivo . The numbers of Paneth cells (lysozyme‐positive cells) in the small intestinal mucosa decreased in mice with ablated HuR compared with those in control littermates. Similarly, primarily cultured HuR‐deficient organoids isolated from IE‐HuR −/− mice also displayed a significant reduction in Paneth cells. HuR deletion also specifically disrupted cellular distribution of TLR2 in the small intestinal epithelium, as shown by a decrease in the levels of apical TLR2 but not TLR4, although it failed to alter total TLR levels. HuR silencing by transfection with siHuR also reduced the levels of membrane TLR2, along with an increase in cytosolic TLR2 in cultured IECs. Mechanistically, HuR directly interacted with the mRNA encoding CNPY3 that was necessary for TLR trafficking to cell surface. HuR silencing inhibited CNPY3 translation without effect on its total mRNA levels. Conclusions These results indicate that 1) HuR is crucial for Paneth cell functions; 2) HuR maintains the apical surface distribution of TLR2; and 2) HuR regulates subcellular trafficking of TLR2 by altering CNPY3 expression posttranscriptionally. Support or Funding Information NIH‐NIDDK (JYW) and Department of Veterans Affairs (JYW&RNJ) This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal .