Hong Wang1, Ran Jing2, Christa Trexler3, Yali Li1, Huayuan Tang1, Zhixiang Pan1, Siting Zhu1, Beili Zhao1, Xi Fang3, Jie Liu4, Ju Chen5, Kunfu Ouyang6. 1. Drug Discovery Center, State Key Laboratory of Chemical Oncogenomics, School of Chemical Biology and Biotechnology, Peking University Shenzhen Graduate School, Shenzhen, 518055, China. 2. Xiangya Hospital, Central South University, Changsha, 410011, China. 3. Department of Medicine, University of California-San Diego, 9500 Gilman Drive, La Jolla, CA, 92093, USA. 4. Department of Pathophysiology, School of Medicine, Shenzhen University, Shenzhen, 518060, China. 5. Department of Medicine, University of California-San Diego, 9500 Gilman Drive, La Jolla, CA, 92093, USA. juchen@ucsd.edu. 6. Drug Discovery Center, State Key Laboratory of Chemical Oncogenomics, School of Chemical Biology and Biotechnology, Peking University Shenzhen Graduate School, Shenzhen, 518055, China. ouyangkunfu@pkusz.edu.cn.
Abstract
BACKGROUND: Inositol 1,4,5-trisphosphate receptors (IP3Rs) are a family of intracellular Ca2+ release channels located on the membrane of endoplasmic reticulum, which have been shown to play critical roles in various cellular and physiological functions. However, their function in regulating gastrointestinal (GI) tract motility in vivo remains unknown. Here, we investigated the physiological function of IP3R1 in the GI tract using genetically engineered mouse models. METHODS: Pdgfrb-Cre mice were bred with homozygous Itpr1 floxed (Itpr1f/f) mice to generate conditional IP3R1 knockout (pcR1KO) mice. Cell lineage tracing was used to determine where Pdgfrb-Cre-mediated gene deletion occurred in the GI tract. Isometric tension recording was used to measure the effects of IP3R1 deletion on muscle contraction. RESULTS: In the mouse GI tract, Itpr1 gene deletion by Pdgfrb-Cre occurred in smooth muscle cells, enteric neurons, and interstitial cells of Cajal. pcR1KO mice developed impaired GI motility, with prolonged whole-gut transit time and abdominal distention. pcR1KO mice also exhibited lethality as early as 8 weeks of age and 50% of pcR1KO mice were dead by 40 weeks after birth. The frequency of spontaneous contractions in colonic circular muscles was dramatically decreased and the amplitude of spontaneous contractions was increased in pcR1KO mice. Deletion of IP3R1 in the GI tract also reduced the contractile response to the muscarinic agonist, carbachol, as well as to electrical field stimulation. However, KCl-induced contraction and expression of smooth muscle-specific contractile genes were not significantly altered in pcR1KO mice. CONCLUSIONS: Here, we provided a novel mouse model for impaired GI motility and demonstrated that IP3R1 plays a critical role in regulating physiological function of GI tract in vivo.
BACKGROUND:Inositol 1,4,5-trisphosphate receptors (IP3Rs) are a family of intracellular Ca2+ release channels located on the membrane of endoplasmic reticulum, which have been shown to play critical roles in various cellular and physiological functions. However, their function in regulating gastrointestinal (GI) tract motility in vivo remains unknown. Here, we investigated the physiological function of IP3R1 in the GI tract using genetically engineered mouse models. METHODS:Pdgfrb-Cre mice were bred with homozygous Itpr1 floxed (Itpr1f/f) mice to generate conditional IP3R1 knockout (pcR1KO) mice. Cell lineage tracing was used to determine where Pdgfrb-Cre-mediated gene deletion occurred in the GI tract. Isometric tension recording was used to measure the effects of IP3R1 deletion on muscle contraction. RESULTS: In the mouseGI tract, Itpr1 gene deletion by Pdgfrb-Cre occurred in smooth muscle cells, enteric neurons, and interstitial cells of Cajal. pcR1KO mice developed impaired GI motility, with prolonged whole-gut transit time and abdominal distention. pcR1KO mice also exhibited lethality as early as 8 weeks of age and 50% of pcR1KO mice were dead by 40 weeks after birth. The frequency of spontaneous contractions in colonic circular muscles was dramatically decreased and the amplitude of spontaneous contractions was increased in pcR1KO mice. Deletion of IP3R1 in the GI tract also reduced the contractile response to the muscarinic agonist, carbachol, as well as to electrical field stimulation. However, KCl-induced contraction and expression of smooth muscle-specific contractile genes were not significantly altered in pcR1KO mice. CONCLUSIONS: Here, we provided a novel mouse model for impaired GI motility and demonstrated that IP3R1 plays a critical role in regulating physiological function of GI tract in vivo.
Entities:
Keywords:
Ca2+ release channel; Gut motility; IP3 receptor; Intestinal pseudo-obstruction
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