A Haploid Expressed Gene Cluster Exists as a Single Chromatin Domain in Human Sperm

doi:10.1074/jbc.270.15.8755

A Haploid Expressed Gene Cluster Exists as a Single Chromatin Domain in Human Sperm (*)

From the (1) Department of Obstetrics and Gynecology and Centers for
(2) Molecular Medicine and Genetics and
(3) Human Growth and Development, Wayne State University School of Medicine, and
(4) Department of Pathology, Harper Hospital, Detroit, Michigan 48201

^§§ To whom correspondence should be addressed:
Dept. of Obstetrics and Gynecology, Wayne State University School of Medicine, 253 CSMC, 275 E. Hancock Ave., Detroit, MI 48201.
Tel.: 313-577-6770; Fax: 313-577-8554; E-mail: steve{at}compbio.med.wayne.edu.

Abstract

Mammalian spermiogenesis is marked by the initial disruption of the nuclear-histone-DNA complex by the transition proteins for ultimate replacement with protamines. The genes for three of these low molecular weight basic nuclear proteins exist as a single linear array of PRM1, PRM2, and TNP2 on human chromosome 16p13.2. To begin to address the mechanism governing their transcriptional potentiation, a region of 40 kilobases of the human genome encompassing these genes was introduced into the germ line of mice. Fluorescence in situ hybridization and Southern analysis showed that this segment of the human genome integrated into independent chromosomal sites while maintaining its fidelity. Transcript analysis demonstrated that the expression of the endogenous mouse protamine Prm1 and Prm2 genes as well as the mouse transition protein Tnp2 gene were expressed along with their human transgene counterparts. The pattern of expression of these transgenic human genes within this multigenic cluster faithfully represented that observed in vivo. In addition, all members of this transgenic gene cluster were expressed in proportions similar to those in human testis. Copy number-dependent and position-independent expression of the transgenic construct demonstrated that the corresponding biological locus was contained within this segment of the human genome. Furthermore, DNase I sensitivity established that in sperm the human PRM1 PRM2 TNP2 genic domain was contained as an 28.5-kilobase contiguous segment bounded by an array of nuclear matrix associated topoisomerase II consensus sites. This is the first description of a multigenic male gamete-specific domain as a fundamental gene regulatory unit. A model of haploid-specific gene determination is presented.

Footnotes

↵^§ These authors contributed equally to this work.
↵^¶ Supported in part by the Dean's Postdoctoral Recruitment Award.
↵* This work was supported in part by Grant 1RO1HD285040A1 from the NICHD, Grant EDUD-US93015 from Sun Microsystems, and FMRE Grant 1064 from Wayne State University (to S. A. K.). 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.
↵¹ The abbreviations used are:

bp

base pair(s)

kb

kilobase(s)

LCR

locus control region

FISH

fluorescence in situ hybridization

SAR

scaffold attachment region

MAR

matrix attachment region

h

human.
↵²J. A. Kramer, S. M. Wykes, J. E. Nelson, and S. A. Krawetz, unpublished observations.