Because androgen function is regulated by its receptors, androgen-androgen receptor signaling is crucial for regulating spermatogenesis. Androgen is mainly testosterone secreted by testis. Based on the results of early studies in goats, the administration of melatonin over an extended period of time increases steroid production, but the underlying mechanism remains unclear. Here, we report the expression of the melatonin membrane receptors MT1 and MT2 and the retinoic acid receptor-related orphan receptor-alpha (RORα) in the goat testis. An in vitro differentiation system using spermatogonial stem cells (SSCs) cultured in the presence of testicular somatic cells was able to support the formation of sperm-like cells with a single flagellum. The addition of 10-7 M melatonin to the in vitro culture system increased RORα expression and considerably improved the efficiency of haploid cell differentiation, and the addition of the RORα agonist CGP52608 significantly increased the testosterone concentration and expression of GATA binding factor 4 (GATA-4). Furthermore, inhibitors of melatonin membrane receptors and a RORα antagonist (T0901317) also led to a considerable reduction in the efficiency of haploid spermatid formation, which was coupled with the suppression of GATA-4 expression. Based on these results, RORα may play a crucial role in enhancing melatonin-regulated GATA-4 transcription and steroid hormone synthesis in the goat spermatogonial stem cell differentiation culture system.

Adult T-cell leukemia (ATL) caused by human T-cell leukemia virus type 1 (HTLV-1) infection, occurs in 2% to 4% of the HTLV-1 carriers with a long latent period, suggesting that additional alterations participate in the development of ATL. To characterize and identify novel markers of ATL, we examined the expression profiles of more than 12 000 genes in 8 cases of acute-type ATL using microarray. One hundred ninety-two genes containing interleukin 2 (IL-2) receptor ␣ were up-regulated more than 2-fold compared with CD4 ؉ and CD4 ؉ CD45RO ؉ T cells, and tumor suppressor in lung cancer 1 (TSLC1), caveolin 1, and prostaglandin D2 synthase showed increased expression of more than 30-fold.

We have identified a novel gene MEL1 (MDS1/EVI1-like gene 1) encoding a zinc finger protein near the breakpoint of t(1; 3)(p36;q21)-positive human acute myeloid leukemia (AML) cells. Here, we studied the structure, expression pattern, and function of MEL1 in leukemia cells. In this study, we have identified 3 transcription start sites, 1 in exon 1 and 2 in exon 2, and 2 kinds of translation products, 170 kDa (MEL1) and 150 kDa (MEL1S). Notably, the 150-kDa band of MEL1S was detected mainly in the t(1;3)(p36;q21)-positive AML cells. By immunoblot analysis and proteolytic mapping, it is suggested that the 150-kDa band of MEL1S in the leukemia cells is translated from the internal initiation codon ATG597 in exon 4 and is mostly lacking the amino-terminal PR domain of MEL1. By the cyclic amplification and selection of targets (CASTing) method for identifying consensus sequences, it was shown that the consensus sequences of MEL1 were included in 2 different consensus sequences for DNA-binding domain 1 and 2 (D1-CONS and D2-CONS) of EVI1. In reporter gene assays, MEL1S activated transcription via binding to D2-CONS; however, the fusion of MEL1 or MEL1S to GAL4 DNA-binding domain (DBD) made them GAL4 binding sitedependent transcriptional repressors. IntroductionThe PRDI-BF1-RIZ1 homologous (PR) domain is a newly recognized amino-terminal module 1 and was first noted for the homologous 100-amino acid region shared between positive regulatory domain I binding factor 1 (PRDI-BF1) (PRDM1) 2 and retinoblastoma-interacting zinc finger protein (RIZ) (PRDM2). 1 PR domain members (PRDMs) are also known to be in the suppressor of var, enhancer of zeste and trithorax (SET) domain superfamily. 3 RIZ is isolated by protein-protein interaction with the retinoblastoma tumor suppressor protein (Rb). 1 Consistent with a potential role in the Rb pathway, RIZ may play an important role in the pathogenesis of human cancer. Interestingly, RIZ produces 2 different gene products, a full-length RIZ1 and a short-form RIZ2 lacking a PR domain at the amino-terminus, which is generated by an alternative transcript derived from an internal promoter. 4 Both transcripts are widely expressed in many organs. However, recent study revealed that the expression rate of RIZ1 is decreased or several point mutations in the RIZ1 coding region exist in many kinds of tumors, suggesting that RIZ1 with a PR domain is a candidate tumor suppressor gene. 5,6 Murine ecotropic virus integration 1 site (Evi-1) zinc finger protein was isolated from common sites of viral integration in murine myeloid leukemia. 7 The human homolog, EVI1 at chromosomal position 3q26, is also transcriptionally activated by several recurrent chromosomal aberrations in acute myeloid leukemia (AML). 8 The most frequent rearrangements are t(3;3)(q21;q26) and inv(3)(q21q26) associated with AML (3q21q26 syndrome) and myelodysplastic syndrome (MDS). 8 A PR domain was later found in the MDS1/EVI1 gene product, which is derived from one of the EVI1 alternative transcripts. 9 The genomic region of ...

DNA methylation plays critical roles in the development and differentiation of mammalian cells, and its dysregulation has been implicated in oncogenesis. This study was designed to determine whether DNA hypomethylation-associated aberrant gene expression is involved in adult T-cell leukemia (ATL) leukemogenesis. We isolated hypomethylated DNA regions of ATL cells compared with peripheral blood mononuclear cells from a carrier by a methylated CpG-island amplification/representational difference analysis method. The DNA regions identified contained MEL1, CACNA1H, and Nogo receptor genes. Sequencing using sodium bisulfite-treated genomic DNAs revealed the decreased methylated CpG sites, confirming that this method detected hypomethylated DNA regions. Moreover, these hypomethylated genes were aberrantly transcribed. IntroductionAdult T-cell leukemia (ATL) is a neoplastic disease of CD4 ϩ T lymphocytes that is etiologically associated with human T-cell leukemia virus type I (HTLV-I). [1][2][3][4][5][6] After transmission, HTLV-I increases the number of infected cells through its viral proteins, including Tax. Tax encoded by the pX region between env and the 3Ј long terminal repeat (LTR) is an oncoprotein with pleiotropic actions, 7,8 including transactivation of the nuclear factor kappaB (NFB), serum responsive factor (SRF), and cyclic adenosine monophosphate (cAMP) response elementbinding protein (CREB) pathways; transrepression of genes, such as DNA polymerase ␤, lck, and p18 genes; and functional inactivation of p53, p16, and mitotic arrest-defective 1 (MAD1). 8,9 With these actions, Tax promotes the proliferation and inhibits apoptosis of infected cells, resulting in their clonal expansion and increased proviral load.The cumulative risk of developing ATL after HTLV-I infection was estimated to be 6% in men and 2% in women. 10 In addition, there is a long latent period before the onset of ATL, suggesting that additional factors other than viral proteins are implicated in leukemogenesis. Although somatic changes of genes, such as mutation of p53 11 or deletion of p16, 12 were reported in ATL, they were not so frequent in ATL cells and were predominantly observed in aggressive forms of ATL, such as acute and lymphoma types. This suggested that these genetic changes were implicated in the progression of ATL. In addition, it has been reported that DNA methylation of the p16 gene silenced its expression, indicating that epigenetic changes were also implicated in leukemogenesis. 13 Epigenetic changes include dysregulated DNA methylation in cancer cells, which consists of hypermethylation and hypomethylation of DNA. 14 Hypermethylation is frequently associated with gene silencing when hypermethylation occurs in the promoter region of genes. 15 The same mechanism is considered to regulate the transcriptional silencing of various tumor suppressor genes, including p16, 16 p15, 17 hMLH1, 18 BRCA1, 19 and GSTP1 genes. 20 From the perspective of the whole genome, genome-wide hypomethylation has been reported in cancer cells...