IGF-I and TGF-β1 have distinct effects on phenotype and proliferation of intestinal fibroblasts

Abstract

This study was designed to identify the single-channel properties and molecular entity of ATP-sensitive K(+) (K(ATP)) channels in guinea pig gastric myocytes with patch-clamp recording and RT-PCR. Pinacidil and diazoxide activated K(ATP) currents in a glibenclamide-sensitive manner. The open probability of channels was enhanced by the application of 10 microM pinacidil from 0.085 +/- 0.04 to 0.20 +/- 0.05 (n = 7) and was completely blocked by 10 microM glibenclamide. Single-channel conductance was 37.3 +/- 2.5 pS (n = 4) between -80 and -20 mV in symmetrical K(+) gradient conditions. In inside-out mode, K(ATP) channels showed no spontaneous openings and were activated by the application of nucleotide diphosphates to the cytoplasmic side. These single-channel properties are similar to those of the nucleotide diphosphate-dependent K(+) channels in vascular smooth muscle, which are composed of Kir6.1 and sulfonylurea receptor (SUR)2B. RT-PCR demonstrated the presence of Kir6.1, Kir6.2, and SUR2B in guinea pig stomach smooth muscle cells. These results suggest that K(ATP) channels in smooth muscle cells of the guinea pig stomach are composed of Kir6.1 and SUR2B.

Identification of Selective Basophil Chemoattractants in Human Nasal Polyps as Insulin-Like Growth Factor-1 and Insulin-Like Growth Factor-2

“…A major consequence of IGF-R1 activation is stimulation of cell growth, i.e., cell proliferation, differentiation, and survival. Fibroblasts are a significant source of IGFs, as well as being responsive to these growth factors in terms of proliferation and collagen production (41). IGF-1 is a growth and differentiation factor for myocytes and can also stimulate proliferation and chemotaxis of vascular and airway smooth muscle cells (42).…”

Epithelial Cells and Their Neighbors I. Role of intestinal myofibroblasts in development, repair, and cancer

“…In both intestinal inflammation (27) and neoplasia (adenomatous polyps) (1), there is an increased number of ␣-SMA(ϩ) MFs in the lamina propria (Fig. 2).…”

“…In the intestine, the most important PDGF agonists appear to be PDGF BB acting through receptors PDGF-R␤␤ and ␣␤ (22, 23). However, EGF, bFGF, IGF-I, and IGF-II, TGF-␤, and CTGF (a downstream mediator of TGF-␤ action) also play a role (11,27). IMFs also contract and become motile in response to endothelin and are relaxed by atrial natriuretic peptide (7).…”

Inflammation modulates fibronectin isoform expression in colonic lamina propria fibroblasts (CLPF)

“…TGF-β expression is upregulated in myofibroblasts at sites of fibrosis in experimental enterocolitis and in CD patients 49 .…”