Mechanosensitivity is required for effective gastrointestinal function. The overall objective of this proposal is to understand the ionic mechanisms that underlie smooth muscle and interstitial cell of Cajal (ICC) mechanosensitivity, to determine the role of ion channelopathies in motility disorders and to establish new roles for ion channel interacting proteins and the lipid environment in the regulation of mechanosensory ion channels in health and in disease. The central hypothesis of this proposal is that mechanosensory ion channels expressed in human intestinal smooth muscle cells and ICC are regulated by specific mechanisms. The Na+ channel is gated by Na+ channel interacting proteins (SCIPs) and the L-type Ca2+ channel by the lipid bilayer. Mutations in the channel subunits themselves and/or the channel interacting proteins can contribute to motility disorders. The central hypothesis will be tested in two specific aims.
Specific Aim 1 will test the hypothesis that the mechanosensitive Na+ current in human intestinal smooth muscle cells and ICC is regulated by SCIPs that make up a functional unit and that mutations in proteins that make up the functional unit can result in disease.
Specific Aim 2 will test the hypothesis that mechanosensitivity of L-type Ca2+ channels is a result of an interaction between the channel and the lipid bilayer. The central hypothesis is supported by preliminary data that show that SCIPs, including telethonin, act in concert with the mechanosensory Na+ channel to create a functional unit, that mutations in the gene (SCN5A) that encodes for Nav1.5 result in gastrointestinal symptoms, that mutations in SCIPs, newly identified in this proposal, are found in patients with motility disorders, and that tension in the lipid bilayer mechanically gates the L-type Ca2+ channel and alters open probability. The PI will test the central hypothesis by the combination of electrophysiological, molecular, and population based techniques. These include patch clamp, immunohistochemistry, Western blots, RT-PCR, SCPCR, qRT-PCR, yeast two hybrid, GST-pulldowns, denaturing high performance liquid chromatography and questionnaire based techniques. Successful completion of the proposed studies has both basic significance and clinical impact. We are now poised to significantly advance our understanding of the components of a functional mechanosensitive Nav1.5 channel and on the mechanism of L-type Ca2+ channel mechanosensitivity. The work will also provide mechanistic information that is relevant to not only the gastrointestinal tract but also to organs such as the heart that also express mechanosensory ion channels and/or ion channel interacting proteins. Understanding the role mutations in ion channels and in ion channel interacting proteins play in motility disorders will not only help determine the cause of these disorders but will also serve to identify future therapeutic targets and strategies to treat motility disorders of the gastrointestinal tract.

Agency
National Institute of Health (NIH)
Institute
National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)
Type
Research Project (R01)
Project #
5R01DK052766-14
Application #
8024563
Study Section
Clinical and Integrative Gastrointestinal Pathobiology Study Section (CIGP)
Program Officer
Hamilton, Frank A
Project Start
1997-09-01
Project End
2012-08-31
Budget Start
2011-02-01
Budget End
2012-08-31
Support Year
14
Fiscal Year
2011
Total Cost
$314,697
Indirect Cost
Name
Mayo Clinic, Rochester
Department
Type
DUNS #
006471700
City
Rochester
State
MN
Country
United States
Zip Code
55905
Alcaino, C; Farrugia, G; Beyder, A (2017) Mechanosensitive Piezo Channels in the Gastrointestinal Tract. Curr Top Membr 79:219-244
Strege, Peter R; Knutson, Kaitlyn; Eggers, Samuel J et al. (2017) Sodium channel NaV1.3 is important for enterochromaffin cell excitability and serotonin release. Sci Rep 7:15650
Strege, Peter R; Mazzone, Amelia; Bernard, Cheryl E et al. (2017) Irritable bowel syndrome (IBS) patients have SCN5A channelopathies that lead to decreased NaV1.5 current and mechanosensitivity. Am J Physiol Gastrointest Liver Physiol :ajpgi000162017
Wang, Fan; Knutson, Kaitlyn; Alcaino, Constanza et al. (2017) Mechanosensitive ion channel Piezo2 is important for enterochromaffin cell response to mechanical forces. J Physiol 595:79-91
Beyder, Arthur; Farrugia, Gianrico (2016) Ion channelopathies in functional GI disorders. Am J Physiol Gastrointest Liver Physiol 311:G581-G586
Beyder, A; Gibbons, S J; Mazzone, A et al. (2016) Expression and function of the Scn5a-encoded voltage-gated sodium channel NaV 1.5 in the rat jejunum. Neurogastroenterol Motil 28:64-73
Neshatian, Leila; Strege, Peter R; Rhee, Poong-Lyul et al. (2015) Ranolazine inhibits voltage-gated mechanosensitive sodium channels in human colon circular smooth muscle cells. Am J Physiol Gastrointest Liver Physiol 309:G506-12
Beyder, Arthur; Mazzone, Amelia; Strege, Peter R et al. (2014) Loss-of-function of the voltage-gated sodium channel NaV1.5 (channelopathies) in patients with irritable bowel syndrome. Gastroenterology 146:1659-1668
Farrugia, Gianrico; Szurszewski, Joseph H (2014) Carbon monoxide, hydrogen sulfide, and nitric oxide as signaling molecules in the gastrointestinal tract. Gastroenterology 147:303-13
Caio, Giacomo; Volta, Umberto; Cerrato, Enrico et al. (2013) Detection of anticonductive tissue autoantibodies in a patient with chronic intestinal pseudo-obstruction and sick sinus syndrome. Eur J Gastroenterol Hepatol 25:1358-63

Showing the most recent 10 out of 33 publications