Interstitial cells of Cajal (ICC) are pacemaker cells that generate spontaneous electrical slow waves, and mediate inputs from motor neurons in the gastrointestinal (GI) tract. Loss or defects in ICC networks are directly linked to GI motility disorders. Recent studies have demonstrated that ICC plays an important role in the development of diabetic gastroenteropathy (DGEP). Patients with DGEP show loss or defects in ICC networks that may lead to GI motility disorders. ICC express the receptor tyrosine kinase, KIT, which is the receptor for stem cell factor. KIT signaling is required for the normal development and maintenance of ICC in the GI tract. Therefore, it is possible that loss of ICC in DGEP may be a result of reduced expression of KIT. Recent studies show that expression of Kit is regulated by microRNAs (miRNAs). Thus, our central hypothesis is that miRNAs targeting Kit inhibit the development and maintenance of ICC in DGEP. To address the hypothesis, we propose the following specific aims: 1) Characterization of microRNAome in ICC, 2) Identification of changes in microRNAs during the development of DGEP, and 3) Suppression of the growth and maintenance of ICC by miRNAs targeting Kit. To achieve the specific aims, we will utilize two animal models Kit+/copGFP and type 2 diabetic Kit+/copGFP;Lepob/ob mutant mice that we have recently generated . Both mice express a bright green fluorescent protein copGFP in a Kit-specific manner, which offers a powerful new model to study the function and genetic regulation of ICC phenotypes. Completion of the specific aims of this project will provide information about the miRNAs expressed specifically by ICC and how this body of regulatory molecules is altered in a major GI motor disorder. Our preliminary data suggest that many of the miRNAs in ICC target Kit. This study will describe a novel molecular mechanism involving miRNAs that inhibit KIT expression. This is an exciting opportunity to understand how KIT expression in ICC is regulated and how ICC are lost during the development of DGEP. Identification of the miRNAs inhibiting KIT expression may aid in the development of a therapeutic antisense miRNA drug that might be useful in blocking or reversing damaged ICC networks in DGEP and other GI motility and functional disorders in which loss of ICC occurs. PUBLIC HEALTH RELEVANCE: Loss of interstitial cells of Cajal (ICC) is directly linked to diabetic gastroenteropathy (DGEP), but the molecular mechanism underlying the ICC disruption is elusive. The present study seeks to uncover a novel mechanism involving microRNAs that lead to the loss of ICC during the development of DGEP.