NK receptors, Substance P, Ano1 expression and ultrastructural features of the muscle coat in Cav-1−/− mouse ileum

Abstract

Caveolin (Cav)-1 is an integral membrane protein of caveolae playing a crucial role in various signal transduction pathways. Caveolae represent the sites for calcium entry and storage especially in smooth muscle cells (SMC) and interstitial cells of Cajal (ICC). Cav-1−/− mice lack caveolae and show abnormalities in pacing and contractile activity of the small intestine. Presently, we investigated, by transmission electron microscopy (TEM) and immunohistochemistry, whether the absence of Cav-1 in Cav-1−/− mouse small intestine affects ICC, SMC and neuronal morphology, the expression of NK1 and NK2 receptors, and of Ano1 (also called Dog1 or TMEM16A), an essential molecule for slow wave activity in gastrointestinal muscles. ICC were also labelled with c-Kit and tachykinergic neurons with Substance P (SP). In Cav-1−/− mice: (i) ICC were Ano1-negative but maintained c-Kit expression, (ii) NK1 and NK2 receptor immunoreactivity was more intense and, in the SMC, mainly intracytoplasmatic, (iii) SP-immunoreactivity was significantly reduced. Under TEM: (i) ICC, SMC and telocytes lacked typical caveolae but had few and large flask-shaped vesicles we called large-sized caveolae; (ii) SMC and ICC contained an extraordinary high number of mitochondria, (iii) neurons were unchanged. To maintain intestinal motility, loss of caveolae and reduced calcium availability in Cav-1–knockout mice seem to be balanced by a highly increased number of mitochondria in ICC and SMC. Loss of Ano-1 expression, decrease of SP content and consequently overexpression of NK receptors suggest that all these molecules are Cav-1–associated proteins.

Absence of caveolin-1 alters heat shock protein expression in spontaneous mammary tumors driven by Her-2/neu expression

“…Although significant, the changes were not dramatic, with small changes observed in Hsp70 and Hsp27 and even less in Gp96. While it is generally accepted that Cav-1 is essential for the formation of caveolae, a recent study has shown by electron microscopy that intestinal cells may still form large size caveolae in the absence of Cav-1 (Cipriani et al 2011), indicating that these cells have Fig. 2 Representative images of the levels of Hsp70, Hsp27, and Gp96 as revealed by IHC.…”

The Significance of Interstitial Cells in Neurogastroenterology

“…103,104 More recently, it has been shown that ICC are anoctamin-1 (ANO1) negative in mice that lack caveolae (caveolin-1 knockout mice). 105 ANO1 is a calcium activated chloride channel that is fundamental to the generation of slow waves, 106,107 again suggesting an important role for caveolae in pacemaker activity. An abundance of mitochondria has been observed in ICC and these organelles are in close apposition to the ER and the plasma membrane (PM).…”

Anoctamin 1 Positive Esophageal Interstitial Cajal Cells in Late Stage Human Embryos

“…Intracellular calcium oscillations periodically activate plasmalemmal channels, such as Ca 21 -activated Cl 2 channels (Takaki et al, 2010). Anoctamin 1 (Ano1, TMEM16A, DOG1) is a major component of the plasmalemmal Ca 21 -activated Cl 2 channels (CaCCs) (Ferrera et al, 2010;Cipriani et al, 2011;Kunzelmann et al, 2011;Shimizu et al, 2013;Simon et al, 2013). In this regard, the evidence of a sublayer of DOG1 positive ICC-MY is suggestive for a subpopulation of ICC-MY being qualified for pacemaking at this early developmental stage.…”