c-kit-Dependent development of interstitial cells and electrical activity in the murine gastrointestinal tract

Abstract

In vivo injection of a neutralizing, monoclonal antibody (ACK2) to the receptor tyrosine kinase (c-kit) disrupts the normal motility patterns of the mouse small intestine. Immunohistochemical studies showed that cells expressing c-kit-like immunoreactivity (c-kit-LI) decreased in numbers in response to ACK2, but the identity of these cells is unknown. We investigated the identity and development of the cells that express c-kit-LI in the mouse small intestine and colon. Cells in the region of the myenteric plexus and deep muscular plexus of the small intestine and in the subserosa, in the myenteric plexus region, within the circular and longitudinal muscle layers, and along the submucosal surface of the circular muscle in the colon were labeled with ACK2. The distribution of cells that express c-kit-LI was the same as that of interstitial cells (ICs). In whole-mount preparations cells with c-kit-LI were interconnected, forming a network similar to the network formed by cells that stained with methylene blue, which has been used as a marker for ICs in the mouse gastrointestinal tract. Immunocytochemistry verified that ICs were labeled with ACK2. Multiple injections of animals with ACK2 between days 0 and 8 post partum (pp) caused a dramatic reduction in the number of ICs compared to control animals. From an ultrastructural point of view, the proliferation and development appeared to be suppressed in some classes of ICs, while others displayed an altered course of development. Functional studies showed that the decrease in ICs was accompanied by a loss of electrical rhythmicity in the small intestine and reduced neural responses in the small bowel and colon. Morphological experiments showed that c-kit-positive cells are ICs, and physiological evidence reinforced the concept that ICs are involved in generation of rhythmicity and translation of neural inputs in gastrointestinal smooth muscles. Controlling the development of ICs provides a powerful new tool for the investigation of the physiological role of these cells.

Interstitial cells of Cajal mediate inhibitory neurotransmission in the stomach.

“…ICC in the stomachs of wild-type (+/+) and mutant (WIWv) mice were examined with antibodies to c-Kit, a specific marker for ICC in murine GI muscles (11)(12)(13)(14). Two types of cells expressed c-Kit-like immunoreactivity (c-Kit-LI) in wild-type animals.…”

“…A parallel arrangement could exist in which ICC and smooth muscle cells are jointly innervated, or neurotransmission could be a serial process in which ICC provide the critical link between neurons and muscle cells. Recently, it was shown that mutations in c-kit, a protooncogene located at the W locus on chromosome 5 in the mouse that encodes a receptor tyrosine kinase (10), or in stem cell factor, the natural ligand for c-Kit receptors, result in developmental defects in some classes of ICC (11)(12)(13)(14). For example, ICC in the myenteric plexus region (IC-MY) of the small intestine are greatly decreased in numbers in these mutants and slow waves are abolished, confirming a role for IC-MY as pacemakers (3,15,16).…”

“…Ultrastructural studies were performed on tissues fixed with glutaraldehyde (2.5%) and postfixed with OS04 (1%), as previously described (13). Ultrathin sections were examined by electron microscopy (model CM10; Phillips Electronic Instruments, Mahwah, NJ).…”

Effects of Imatinib Mesylate in Interstitial Cells of Cajal from Murine Small Intestine

“…7) ICCs express the proto-oncogene c-kit, 8) and signalling via the receptor kinase gene product, Kit, is essential for the development of phenotype and electrical rhythmicity. 9) Although ICCs express c-kit receptors, it is not established whether these are functional in the adult, although they are important in developing cells. Imatinib mesylate (Glivec ® ; Novartis Pharmaceuticals) is a selective inhibitor of c-kit receptor tyrosine kinases, and has U.S.A. Food and Drug Administration approval for the treatment of Philadelphia chromosome-positive chronic myeloid leukaemia (CML) and c-kit positive gastrointestinal stromal tumours (GIST).…”

Oncogenic Kit signaling and therapeutic intervention in a mouse model of gastrointestinal stromal tumor

“…T he Kit receptor tyrosine kinase has a critical role in the normal development and function of the interstitial cells of Cajal (ICC), as well as in hematopoietic cell populations, gametogenesis, and melanogenesis during embryonic development and in the postnatal organism (1)(2)(3). The finding of Kit receptor-activating mutations in human tumors, including gastrointestinal stromal tumor (GIST), seminomas, and mastocytosis, as well as some acute myelogenous leukemias, suggested a role for Kit in oncogenesis.…”