Sequence, Genomic Organization, and Expression of the Novel Homeobox Gene Hesx1

doi:10.1074/jbc.270.8.3869

Sequence, Genomic Organization, and Expression of the Novel Homeobox Gene Hesx1(*)

From the Department of Biochemistry, University of Adelaide, Adelaide, S. A. 5005, Australia

** To whom correspondence should be addressed. Tel.: 61-83035354; Fax: 61-83034348.

↵^¶ Present address: Dept. of Obstetrics and Gynaecology, Flinders Medical Centre, Flinders Dr., Bedford Park, S.A. 5042, Australia.

Abstract

Extensive analyses of homeobox gene expression and function during murine embryogenesis have demonstrated that homeobox gene products are key components in the establishment of pattern formation and regional identity during development. In this paper we report the molecular characterization and expression of a novel murine homeobox sequence, Hesx1, isolated from pluripotent embryonic stem cells. Hesx1 is expressed as two transcripts of 1.0 and 1.2 kilobases which encode an identical 185 amino acid open reading frame. The transcripts differ in the 3′-untranslated region due to the differential utilization of a weak splice donor site located immediately downstream of the translation termination codon. The Hesx1 homeodomain shared 80% identity with the Xenopus homeoprotein XANF-1 and was less than 50% related to other homeodomain sequences. Hesx1 and XANF-1 therefore constitute the founder members of a new homeodomain class. Hesx1 expression was down-regulated during embryonic stem cell differentiation and was detected in tissue-specific RNA samples derived from the embryonic liver, and at lower levels in viscera, amnion, and yolk sac. Expression in adult mice was not detected. These sites of expression are consistent with a role for Hesx1 in the regulation of developmental decisions in the early mouse embryo and during fetal hematopoiesis.

Footnotes

↵^§ Recipient of an Australian Postgraduate Research Award.
↵* This work was supported by an Australian Research Council Grant. The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore by hereby marked “advertisement” in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.

The nucleotide sequence(s) reported in this paper has been submitted to the GenBank(TM)/EMBL Data Bank with accession number(s) X80040[GenBank].
↵¹ The abbreviations used are:

ES

embryonic stem

bp

base pair(s)

MOPS

3-[N-morpholino]propanesulfonic acid

kb

kilobase(s).
↵²P. Q. Thomas and P. D. Rathjen, manuscript in preparation.
- Received July 1, 1994.
- Revision received November 22, 1994.