Proteins of interstitial cells of Cajal and intestinal smooth muscle, colocalized with caveolin-1.
The murine jejunum and lower esophageal sphincter (LES) were examined to determine the locations of various signaling molecules and their colocalization with caveolin-1 and one another. Caveolin-1 was present in punctate sites of the plasma membranes (PM) of all smooth muscles and diffusely in all classes of interstitial cells of Cajal (ICC; identified by c-kit immunoreactivity), ICC-myenteric plexus (MP), ICC-deep muscular plexus (DMP), ICC-serosa (ICC-S), and ICC-intramuscularis (IM). In general, all ICC also contained the L-type Ca(2+) (L-Ca(2+)) channel, the PM Ca(2+) pump, and the Na(+)/Ca(2+) exchanger-1 localized with caveolin-1. ICC in various sites also contained Ca(2+)-sequestering molecules such as calreticulin and calsequestrin. Calreticulin was present also in smooth muscle, frequently in the cytosol, whereas calsequestrin was present in skeletal muscle of the esophagus. Gap junction proteins connexin-43 and -40 were present in circular muscle of jejunum but not in longitudinal muscle or in LES. In some cases, these proteins were associated with ICC-DMP. The large-conductance Ca(2+)-activated K(+) channel was present in smooth muscle and skeletal muscle of esophagus and some ICC but was not colocalized with caveolin-1. These findings suggest that all ICC have several Ca(2+)-handling and -sequestering molecules, although the functions of only the L-Ca(2+) channel are currently known. They also suggest that gap junction proteins are located at sites where ultrastructural gap junctions are know to exist in circular muscle of intestine but not in other smooth muscles. These findings also point to the need to evaluate the function of Ca(2+) sequestration in ICC.
Department of Pharmacology, University of Alberta, 9-10 Medical Sciences Bldg., Edmonton, Alberta, Canada T6G 2H7.
Woo Jung
WJ
Cho
E E
EE
Daniel
D000818:Animals; D020746:Calcium Channels, L-Type / Q000378:metabolism; D002155:Calsequestrin / Q000378:metabolism; D051242:Caveolin 1; D022461:Caveolins / Q000378:metabolism*; D018031:Connexin 43 / Q000378:metabolism; D017630:Connexins / Q000378:metabolism; D049630:Esophageal Sphincter, Lower / Q000166:cytology / Q000502:physiology; D005455:Fluorescent Antibody Technique; D017629:Gap Junctions / Q000502:physiology; D007413:Intestinal Mucosa / Q000378:metabolism*; D007422:Intestines / Q000166:cytology / Q000294:innervation; D007583:Jejunum / Q000187:drug effects / Q000378:metabolism; D051379:Mice; D008807:Mice, Inbred BALB C; D009130:Muscle, Smooth / Q000166:cytology / Q000294:innervation / Q000378:metabolism*; D009419:Nerve Tissue Proteins / Q000378:metabolism; D009569:Nitric Oxide / Q000502:physiology; D019001:Nitric Oxide Synthase / Q000378:metabolism; D052248:Nitric Oxide Synthase Type I; D010275:Parasympathetic Nervous System / Q000502:physiology; D011506:Proteins / Q000378:metabolism*; D019009:Proto-Oncogene Proteins c-kit / Q000378:metabolism; D019831:Sodium-Calcium Exchanger / Q000378:metabolism; D000097003:Gap Junction alpha-5 Protein
D020746:Calcium Channels, L-Type; D002155:Calsequestrin; D051242:Caveolin 1; D022461:Caveolins; D018031:Connexin 43; D017630:Connexins; D009419:Nerve Tissue Proteins; D009569:Nitric Oxide; D019001:Nitric Oxide Synthase; D052248:Nitric Oxide Synthase Type I; D011506:Proteins; D019009:Proto-Oncogene Proteins c-kit; D019831:Sodium-Calcium Exchanger; D000097003:Gap Junction alpha-5 Protein; C495541:Cav1 protein, mouse; C110374:sodium-calcium exchanger 1; C496321:Nos1 protein, mouse