DAZ Family Proteins Exist Throughout Male Germ Cell Development and Transit from Nucleus to Cytoplasm at Meiosis in Humans and Mice1

Abstract

The human DAZ gene family is expressed in germ cells and consists of a cluster of nearly identical DAZ (deleted in azoospermia) genes on the Y chromosome and an autosomal homolog, DAZL (DAZ-like). Only the autosomal gene is found in mice. Y-chromosome deletions that encompass the DAZ genes are a common cause of spermatogenic failure in men, and autosomal homologs of DAZ are essential for testicular germ cell development in mice and Drosophila. Previous studies have reported that mouse DAZL protein is strictly cytoplasmic and that human DAZ protein is restricted to postmeiotic cells. By contrast, we report here that human DAZ and human and mouse DAZL proteins are present in both the nuclei and cytoplasm of fetal gonocytes and in spermatogonial nuclei. The proteins relocate to the cytoplasm during male meiosis. Further observations using human tissues indicate that, unlike DAZ, human DAZL protein persists in spermatids and even spermatozoa. These results, combined with findings in diverse species, suggest that DAZ family proteins function in multiple cellular compartments at multiple points in male germ cell development. They may act during meiosis and much earlier, when spermatogonial stem cell populations are established.

Differential expression of fertility genes boule and dazl in Chinese sturgeon (Acipenser sinensis), a basal fish

“…8). Such a protein expression pattern is found in frog (Mita and Yamashita 2000), mouse (Ruggiu et al 1997) and human (Reijo et al 2000;Xu et al 2001). In Chinese sturgeon, dazl expression is more similar to that of medaka, as opposed to trout, in which dazl persists in postmeiotic spermatids (Fig.…”

“…Such a protein expression pattern has been identified in frogs (Mita and Yamashita 2000), mice (Ruggiu et al 1997) and humans (Reijo et al 2000). Nonetheless, the post-meiotic DAZL protein expression in mammals is disputed (Reijo et al 2000;Vangompel and Xu 2011;Xu et al 2001). Finally, the expression pattern of the third family member boule varies according to species.…”

“…Generally, they are transcribed continuously from embryonic stem cells to primordial germ cell specification and into spermatogenesis up until round spermatids in males (Vangompel and Xu 2011) and in all the stages of oogenesis (Li et al 2011). Such a protein expression pattern has been identified in frogs (Mita and Yamashita 2000), mice (Ruggiu et al 1997) and humans (Reijo et al 2000). Nonetheless, the post-meiotic DAZL protein expression in mammals is disputed (Reijo et al 2000;Vangompel and Xu 2011;Xu et al 2001).…”

GDNF Signaling Regulates YBX1/mRNA Interactions in Mouse Spermatogonia.

“…The most common functions of these 14 genes are splicing and translational control. Included on the list are two known pan-germ cell markers DAZL and DDX4 (VASA), RNA binding proteins expressed exclusively by germ cells including SSCs, which are necessary for spermatogenesis [156,158,162,181]. These established germ cell markers serve as internal controls and help to validate the microarray experimental design.…”

Tracing of Xenopus tropicalis germ plasm and presumptive primordial germ cells with the Xenopus tropicalis DAZ‐like gene

“…In X. laevis, some genes expressed specifically in germ plasm have been isolated, including Xdazl (Houston et al, 1998), Xcat-2 (Mosquera et al, 1993), Xpat (Hudson and Woodland, 1998). Xdazl encodes an RNA-binding protein homologous to human autosomal DAZL (Deleted in Azoospermia-like; Saxena et al, 1996;Reijo et al, 2000). The DAZ gene family is implicated in the meiotic differentiation of pPGCs in a diversity of organisms from insects to mammals and has a highly conserved animo acid sequence among human, mouse (Cooke et al, 1996), X. laevis, zebrafish (Maegawa et al, 1999), and Drosophila (Eberhart et al, 1996).…”