Gene expression of connective tissue growth factor (CTGF/CCN2) in calcifying tissues of normal and cbfa1-null mutant mice in late stage of embryonic development

Abstract

Connective tissue growth factor (CTGF/CCN2), one of the most recently described growth factors, is produced by chondrocytes, vascular endothelial cells, and transforming growth factor (TGF)-beta-stimulated fibroblasts. CTGF was isolated from a chondrosarcoma-derived chondrocytic cell line, HCS-2/8, and found to be normally expressed in cartilage tissues, especially in hypertrophic chondrocytes, and also to stimulate both the proliferation and the differentiation of chondrocytes in vitro. Therefore, CTGF is thought to be one of the most important regulators of endochondral ossification in vivo. Herein we describe the expression pattern of the ctgf gene in the calcifying tissues of normal developing mouse embryos in comparison with that in core binding factor a1 (Cbfa1)-targeted mutant (cbfa1-null) mouse embryos, in which impaired development and growth were characteristically observed in the skeletal system. After 15 days of development (E15), the expression of ctgf was detected in the zone of hypertrophy and provisional calcification, in which ossification proceeds toward the epiphysis during the skeletal development of the mouse embryo. Furthermore, ctgf was expressed in developing molar and incisal tooth germs around the perinatal stage. However, no expression of the gene was found in the cbfa1-null mouse embryos. These results indicate that CTGF may have certain important roles in the development of the calcifying tissues in the mouse embryo.

<b>A systematic analysis for localization of predominant growth factors and their receptors involved in murine tooth germ differentiation using </b><i><b>in situ</b></i><b> hybridization </b><b>technique </b>

“…It was reported by a study employing in situ hybridization analysis that the predominant expression site of CTGF and Fisp12 was preameloblasts at the bell stage, and their expression decreased in intensity in secreting ameloblasts (22). Another in situ hybridization study of the mouse tooth germ reported that CTGF was expressed equally in ameloblasts and odontoblasts in the late developmental stage (29). However, in the present study, no significant expression of CTGF was found in either preameloblasts or ameloblasts.…”

Runx2/Smad3 Complex Negatively Regulates TGF-β-Induced Connective Tissue Growth Factor gene Expression in Vascular Smooth Muscle Cells

“…In fact, in situ hybridization studies demonstrated that CTGF expression is correlated with Runx2 expression during embryonic skeletal development; no CTGF mRNA was detected in Runx2 null mice in chondrocytes 38) . In this regard, it is interesting to note that, unlike in chondrocytes, Runx2 represses CTGF gene expression in VSMCs, and Runx2-positive cells scarcely express CTGF in atherosclerotic plaque.…”

Ectodysplasin has a dual role in ectodermal organogenesis: inhibition of Bmp activity and induction of Shh expression

“…Interestingly, follistatin is expressed in the tooth, hair and feather placodes (Ferguson et al, 1998;Patel et al, 1999;Nakamura et al, 2003), and is localized to the enamel knot of E14 molar teeth (Wang et al, 2004b). Also Ccn2, a modular multifunctional protein with known ability to inhibit Bmp signalling (Abreu et al, 2002), is expressed in the epithelium of developing teeth, and is localized to the enamel knot of the cap stage tooth and is found later in preameloblasts (Shimo et al, 2002;Friedrichsen et al, 2003;Yamaai et al, 2005). Although ectodin, a modulator of Bmp and Wnt pathways, is mainly epithelial, its expression domain does not significantly overlap with that of Edar (Laurikkala et al, 2003).…”