Testis-Specific Histone H1t Gene Is Hypermethylated in Nongerminal Cells in the Mouse1

Abstract

The testis-specific histone H1t gene is expressed only in pachytene primary spermatocytes during spermatogenesis. There is a correlation between the specific binding of testis nuclear proteins to a rat histone H1t promoter sequence, designated the H1t/TE element, and the onset of transcription in primary spermatocytes. Our laboratory has shown that mice bearing the rat gene with a deletion of the TE promoter element and replacement with a heterologous stuffer DNA fragment fail to express the rat H1t transgene in any tissue. In this study we report that five CpGs located within the H1t proximal promoter, including two CpGs located within the essential TE promoter element, contain unmethylated cytosines in vivo in genomic DNA derived from primary spermatocytes where the H1t gene is expressed. All seven CpGs are hypermethylated in vivo in genomic DNA derived from liver cells where gene expression is repressed. Further, in vitro methylation of an H1t promoter-driven reporter plasmid markedly reduced expression in a transient transfection assay system. These results suggest that cytosine methylation may contribute to the transcriptional silencing of the testis-specific histone H1t gene in nonexpressing tissues such as liver.

Prostate cancer is characterized by epigenetic silencing of 14-3-3σ expression

“…Consistent with a role of gene repression mediated by CpG methylation in tumorigenesis, inactivation of MBD2 suppresses intestinal tumorigenesis in Apc min mice (Sansom et al, 2003). In PCa, CpG hypermethylation and subsequent loss of expression have been reported for a limited number of genes: for example, GSTP1 is silenced in B90%, RASSF1A in B63% and RARb2 in B79% of primary PCa (Nakayama et al, 2001;Singal et al, 2001;Kuzmin et al, 2002). CpG methylation of GSTP1 has proven useful for diagnosis of PCa cells in biopsies and body fluids (Harden et al, 2003).…”

“…A large number of genes were found to be induced after treatment with 5Aza-2 0 dC plus TSA vs TSA alone (Lodygin et al, 2002). GSTP1, a gene known to be hypermethylated in the majority of PCa (Singal et al, 2001), was induced 1.87-fold in LNCaP cells after combined treatment with 5Aza-2 0 dC and TSA. The demethylation and induction of GSTP1 were confirmed by MSP and RT-PCR analysis (Figure 1b and c).…”

Transcriptional regulation by the estrogen receptor of antioxidative stress enzymes and its functional implications

“…Thus, in cultured human breast cancer cell lines, GSTP1 is exclusively expressed in ER-negative cells but is undetectable in ERpositive cells. Epigenetic silencing through promoter hypermethylation of GST-Pi gene is associated with breast, prostate, and renal cancer (Esteller et al, 1998;Singal et al, 2001).…”

“…The reporter construct containing GST-Pi gene promoter region À242/ þ 85 has been previously described (Singal et al, 2001). The GST-Pi-1 and GST-Pi-2 gene promoter reporter constructs representing À124/À84 and À83/À33, respectively, were constructed using the following oligonucleotides: 5 0 -cgcgcagcggccgccggggctggggccggcgggagtccgcgggaccctccagaag-3 0 , 5 0 -cgcgagcggccggcgccgtgactcagcactggggcggagcggggcgggaccaccc-3 0 .…”

Frequent hypermethylation of the RASSF1A gene in prostate cancer

“…The most frequent genomic alteration, thus far detected, is hypermethylation of the GSTP1 promoter region (490%) in prostate carcinoma (Lee et al, 1994). It has been demonstrated that methylation of the GSTP1 promoter region results in loss of expression of GSTP1 in prostate cancer cells (Singal et al, 2001;Lin et al, 2001). The methylation status of GSTP1 is currently used in clinical trials to act as a promising diagnostic marker for prostate carcinoma in the United States (Goessl et al, 2001;Cairns et al, 2001).…”