Expression of an engrailed‐like gene during development of the early embryonic chick nervous system

Abstract

The engrailed gene has been identified in Drosophila as an important developmental gene involved in the control of segmentation. Here we describe the embryonic expression of a chicken gene, ChickEn (Darnell et al.: J Cell Biol 103(5):311a, 1986), which contains homology to the Drosophila engrailed gene. Northern blots of early chick embryo tissue poly(A)+ RNA resulted in hybridization to at least three bands expressed predominantly in the brain/head region when probed with ChickEn genomic fragments. Eight cDNA clones generated from embryonic day 6 (stage 29-30) chick brain poly(A)+ RNA are identical in their nucleotide sequence with the ChickEn genomic clone. In situ hybridization to sections of 4-day (stage 24) embryos indicated that ChickEn transcripts were concentrated in the posterior mesencephalon and anterior metencephalon. In cultures of chick cranial neural crest cells (eight to nine somites; stage 9) ChickEn transcripts were localized in a subset (approx. 8%) of cells examined after 2 days in culture. A mouse monoclonal antibody, inv-4D9D4, made by Coleman and Kornberg recognizes the engrailed-like homeo domain of the engrailed and invected proteins (Martin-Blanco, Coleman, and Kornberg, personal communication). Patel, Coleman, Kornberg and Goodman (unpublished) have shown that this antibody binds to the hindbrain of 2-day-old chick embryos. We have confirmed these results and shown that this antibody binds to the same region of 4-day (stage 24) chick brains that in situ hybridization showed contained ChickEn transcripts. This antibody also recognizes a homeo domain-containing ChickEn peptide expressed as a beta-galactosidase fusion protein in Drosophila cell culture. We have not detected ChickEn protein in any tissue prior to eight to nine somites (stage 9). These results delineate the major expression pattern of the ChickEn gene during early (prior to stage 30) embryonic development in the chick.

Expression patterns of engrailed‐like proteins in the chick embryo

“…Because E n proteins also localize to cell nuclei, they may act as transcription factors (for reviews of homeodomain function see Levine and Hoey, 1988;Scott et al, 1989). For these reasons and because of their highly conserved patterns of expression during fish, amphibian, avian, and mammalian development it is thought that E n genes may play important roles during vertebrate embryogenesis Gardner et al, 1988;Davidson et al, 1988;Njolstad and Rose, 1988;Patel et al, 1989;Hemmati-Brivanlou and Harland, 1989;HemmatiBrivanlou et al, 1991;Hatta et al, 1991;Gardner and Barald, 1991).…”

“…We have previously reported the localization of chick En-2 mRNA by in situ hybridization (Gardner et al, 1988) and protein localization by antibody staining with the monoclonal antibody (MAb) 4 0 9 (Gardner et al, 1988. This antibody was developed by Coleman and Kornberg and its extensive species cross-reactivity was described by Patel et al (1989).…”

“…Previous work has led to proposals that chick En genes play a role in neurogenesis and the regionalization of the chick cranial neuroepithelium (Gardner et al, 1988;Pate1 et al, 1989;Martinez and AlvaradoMallart, 1990;Alvarado-Mallart et al, 1990;Martinez et al, 1991;Davis et al, 1991;Gardner and Barald, 1991). Based on our new observations we suggest that chick En protein may also be involved in inductive interactions between the germ layers, in the segmentation of the head mesenchyme, and in the behavior of cells within the somitic mesoderm.…”

Changes in dorsoventral but not rostrocaudal regionalization of the chick neural tube in the absence of cranial notochord, as revealed by expression of Engrailed‐2

“…Recent in vitro experiments in Xenopus have suggested that a subset of this mesoderm, the anterior notochord, can provide suf-0 1992 WILEY-LISS, INC. ficient positional information to the neuroectoderm to result in the expression of a spatially-restricted molecular marker, , in the mesencephalon and anterior metencephalon (Hemmati-Brivanlou et al, 1990). In a variety of vertebrate species, En-2 expression has been detected in this restricted region of the developing central nervous system beginning around the time of formation of the first somite (Davidson et al, 1988;Davis et al, 1988;Fjose et al, 1988;Gardner et al, 1988;Hemmati-Brivanlou and Harland, 1989;Patel et al, 1989). In avian embryos, normal expression of the En-2 protein has been demonstrated specifically in nuclei of the mesencephalon and cranial metencephalon (Gardner et al, 1988;Patel et al, 1989;Martinez and Alvarado-Mallart, 1990) and in a subset of adjacent neural crest cells (Gardner et al, 1988).…”

“…In a variety of vertebrate species, En-2 expression has been detected in this restricted region of the developing central nervous system beginning around the time of formation of the first somite (Davidson et al, 1988;Davis et al, 1988;Fjose et al, 1988;Gardner et al, 1988;Hemmati-Brivanlou and Harland, 1989;Patel et al, 1989). In avian embryos, normal expression of the En-2 protein has been demonstrated specifically in nuclei of the mesencephalon and cranial metencephalon (Gardner et al, 1988;Patel et al, 1989;Martinez and Alvarado-Mallart, 1990) and in a subset of adjacent neural crest cells (Gardner et al, 1988). We have also found En-2 expression in these regions as well as in the overlying surface ectoderm (Fig.…”