Id expression during mouse development: A role in morphogenesis

Abstract

We have characterized the spatial and temporal pattern of Id transcription during mouse embryogenesis. The Id gene encodes a helix-loophelix (HLH) protein which can heterodimerize with the ubiquitously expressed HLH protein products of the E2A gene, and prevent them from binding DNA either alone or as a heterodimer with tissue specific HLH transcription factors such as the muscle determination gene, MyoDl (Benezra et al., 1990 Cell 61:49-59). SinceId has been shown to be down-regulated during induced differentiation in several cell lines, it has been postulated that Id plays a general inhibitory role in cell differentiation (Benezra et al., 1990). In situ analysis of Id mRNA expression in the mouse embryo was performed in order to determine whether the pattern of Id expression is consistent with this postulate. A detailed study throughout the entirety of mouse postimplantation development reveals that Id is expressed upon gastrulation at very high levels in almost all regions of the mouse embryo and expression declines as embryogenesis proceeds. In skeletal muscle, in which the inhibitory action of Id has been established in tissue culture models (Benezra et al., 19901, Id and the HLH myogenic factors are expressed in a mutually exclusive manner suggesting that myogenic precursors do not express both types of HLH gene products. In addition, Id colocalizes both spatially and temporally with Hox-7.1, a murine homeobox gene which is associated with regions of high cell proliferation and positional fate assignment. 0 1992 Wiley-Liss, Inc.

Expression of M‐twist during postimplantation development of the mouse

“…From the initial expression analysis of M-twist (Wolf et al, 1991), it was concluded that the expression pattern is reminiscent to that of Id1 and Msxl, both of which are inhibitors of differentiation (Sassoon, 1993;Wang et al, 1992;Song et al, 1992). This more detailed investigation of M-twist expression confirms this assumption for some areas like the limb bud and the developing heart valves, where all three genes are expressed, and the somites, where Id1 and M-twist are colocalized .…”

Expression patterns of Id1, Id2, and Id3 are highly related but distinct from that of Id4 during mouse embryogenesis

“…The overall postgastrulational expression pattern of Id genes described in this study is as follows: Id1 (Wang et al, 1992;Duncan et al, 1992;Evans and O'Brien, 1993; this work), Id2 and Id3 are expressed in multiple tissues, and the expression patterns among them exhibit extensive overlap ( Fig. 1.1-4).…”

“…During axial skeleton development, Id1 (Wang et al, 1992;Evans and OBrien, 1993; this work), Id2, and Id3 signals are first observed in the 10.5 dpc somites. The somitic expression of these Id genes is mainly located in the sclerotome, and very weak signals appear in the dermatome.…”

“…The somitic expression of these Id genes is mainly located in the sclerotome, and very weak signals appear in the dermatome. The intervening myotome is devoid of any Id signals (data not shown) (for Idl, see Wang et al, 1992;Evans and OBrien, 1993;this work). In the 11.5 dpc sclerotome, the expression of all three Id genes appears in the rostral half which contains less cells ( Fig.…”

“…The embryonic expression pattern of Id1 has been determined by in situ hybridization analysis (Duncan et al, 1992(Duncan et al, , 1994Evans and O'Brien, 1993;Wang et al, 1992). Id1 expression appears in many tissues and its expression roughly correlates with the less differentiated state of the cells.…”