Male-specific transcription initiation of the C4-Slp gene in mouse liver follows activation of STAT5

Male-specific transcription initiation of the C4-Slp gene in mouse liver follows activation of STAT5

^*Unité d’Immunogénétique et Institut National de la Santé et de la Recherche Médicale, U. 276, Institut Pasteur, 25 rue du Docteur Roux, 75724 Paris Cedex 15, France; and ^§Department of Cell Genetics and ^‖Mammalian Genetics Laboratory, National Institute of Genetics, Yata-1111, Mishima 411, Japan

Communicated by Susumu Ohno, Beckman Research Institute of the City of Hope, Duarte, CA (received for review March 26, 1998)

Abstract

The mouse genes encoding the constitutively expressed complement component C4 and its closely related isoform C4-Slp (sex-limited protein), which is expressed only in male animals of several strains, provide a unique model to study sequence elements and trans-acting factors responsible for androgen responsiveness. Our previous studies have shown that hormonal induction of C4-Slp is mediated by a sex-specific pattern of growth hormone secretion. Promoter analyses in vitro have led to contradictory conclusions concerning the significance of C4-Slp-specific sequences in the 5′ flanking region. Mutant mice carrying the H-2 ^aw18 haplotype, which is characterized by a large deletion in the S region covering the C4 and 21-OHase A genes, permit the direct in vivo analysis of C4-Slp transcription, unhindered by the presence of C4. Run-on analysis of transcription in liver nuclei of males and females of this strain demonstrated a 100-fold higher transcriptional activity in males, essentially determined at the transcription initiation level. The androgen dependence of transcription initiation was confirmed by run-on analysis of testosterone-treated females, where transcriptional activity started after 6 days of androgen treatment and reached male levels after 20 days. Conversely, the growth hormone-regulated activity of transcription factor STAT5 was already detected in liver nuclei after 48 hr of androgen treatment. Furthermore, we demonstrate that activated STAT5 recognizes in vitro two upstream γ interferon-activated sequence (GAS) elements of the C4-Slp gene, centered at positions −1969 and −1831. We postulate that binding of STAT5 to these C4-Slp-specific GAS elements plays a crucial role in the chromatin remodelings that lead to transcriptional competence of the C4-Slp gene in the liver.

liver gene expression/growth hormone secretion/complement component C4/sexual dimorphism

Footnotes

↵ † Present address: Institut National de la Santé et de la Recherche Médicale, U.363, Institut Cochin de Genetique Moleculaire, Hôpital Cochin, 27 rue du Fg St. Jacques 75014 Paris, France.
↵ ‡ To whom reprint requests should be addressed. e-mail: mtosi{at}pasteur.fr.
↵ ¶ Present address: Laboratory of Molecular Pathology, Department of Immunology, National Institute of Animal Health, 3-1-1 Kannon-dai, Tsukuba, Ibaraki 305-0856, Japan.
↵ ** Present address: The Graduate University for Advanced Studies, Hayama, Kanagawa-ken, 240-0193, Japan.
↵ ‡‡ Deceased April 19, 1997.
ABBREVIATIONS:

C4-Slp,

sex-limited protein and isoform of the fourth component of mouse complement;

GAS,

γ interferon-activated sequence;

GH,

growth hormone