Role of NF-Y in In Vivo Regulation of the γ-Globin Gene

The solitary LTRs of ERV-9 human endogenous retrovirus are middle repetitive DNAs associated with 3,000 -4,000 human gene loci including the ␤-globin gene locus where the ERV-9 LTR is juxtaposed to the locus control region (␤-LCR) far upstream of the globin genes. The ERV-9 LTRs are conserved during primate evolution, but their function in the primate genomes is unknown. Here, we show that in transgenic zebrafish harboring the ␤-globin ERV-9 LTR coupled to the GFP gene, the LTR enhancer was active and initiated synthesis of GFP mRNA in oocytes but not in spermatozoa, and GFP expression in the embryos was maternally inherited. The LTR enhancer was active also in stem͞ progenitor cell regions of adult tissues of transgenic zebrafish. In human tissues, ERV-9 LTR enhancer was active also in oocytes and stem͞progenitor cells but not in spermatozoa and a number of differentiated, adult somatic cells. Transcriptional analyses of the human ␤-globin gene locus showed that the ␤-globin ERV-9 LTR enhancer initiated RNA synthesis from the LTR in the direction of the downstream ␤ locus control region and globin genes in ovary and erythroid progenitor cells. The findings suggest that, during oogenesis, ERV-9 LTR enhancers in the human genome could activate the cis-linked gene loci to synthesize maternal mRNAs required for early embryogenesis. Alternatively, the ERV-9 LTR enhancers, in initiating RNA syntheses into the downstream genomic DNAs, could transcriptionally potentiate and preset chromatin structure of the cis-linked gene loci in oocytes and adult stem͞progenitor cells.

Section: Discussionmentioning

confidence: 99%

The LTR enhancer of ERV-9 human endogenous retrovirus is active in oocytes and progenitor cells in transgenic zebrafish and humans

Yang

Wang

et al. 2004

“…To examine whether the V205M mutation reduces GATA-1 access to sites other than the ␤-major promoter, we examined HS2 and HS4 of the LCR, which, like HS3, are bound by GATA-1 in vivo (33)(34)(35). We found that although FOG-1 binding appears to be dispensable for GATA-1 access to HS4 (Fig.…”

Section: Fog-1 Requirement For Gata-1-er Occupancy At Erythroid Regulmentioning

confidence: 99%

Context-dependent regulation of GATA-1 by friend of GATA-1

Letting

Chen²,

Rakowski³

et al. 2003

126

134

The transcription factor GATA-1 and its cofactor, friend of GATA-1 (FOG-1), are essential for normal erythroid development. FOG-1 physically interacts with GATA-1 to augment or inhibit its activity. The mechanisms by which FOG-1 regulates GATA-1 function are unknown. By using an assay that is based on the phenotypic rescue of a GATA-1-null erythroid cell line, we found that a conditional form of GATA-1 (GATA-1-ER) strongly induced histone acetylation at the ␤-major globin promoter in vivo, consistent with previous results. In contrast, GATA-1 bearing a point mutation that impairs FOG-1 binding [GATA-1(V205M)-ER] failed to induce high levels of histone acetylation at this site. However, at DNase I-hypersensitive site (HS)3 of the ␤-globin locus control region, GATA-1-induced histone acetylation was FOG-1-independent. Because the V205M mutation does not disrupt GATA-1 binding to DNA templates in vitro, we were surprised to find that in vivo GATA-1(V205M)-ER fails to bind the ␤-globin promoter. However, at HS3, DNA binding by GATA-1 was FOG-1-independent, thus correlating histone acetylation with GATA-1 occupancy. Examination of additional GATA-1-dependent regulatory elements showed that the interaction with FOG-1 is required for GATA-1 occupancy at select sites, such as HS2, but is dispensable at others, including the FOG-1-independent GATA-1 target gene EKLF. Remarkably, at the GATA-2 gene, which is repressed by GATA-1, interaction with FOG-1 was dispensable for GATA-1 occupancy and was required for transcriptional inhibition and histone deacetylation. These results indicate that FOG-1 employs distinct mechanisms when cooperating with GATA-1 during transcriptional activation and repression.globin ͉ chromatin ͉ histones ͉ acetylation

“…ChIPs were performed as described (24,25) with minor modifications. One spleen, or brain, or six yolk sacs were used per condition.…”

Section: Methodsmentioning

confidence: 99%

Developmental specificity of recruitment of TBP to the TATA box of the human γ-globin gene

Duan

Fang

Rohde

et al. 2002

Self Cite

It is unclear whether the core promoter is involved in developmental regulation. To address this question, we mutated the TATA box of the human ␥-globin gene, produced transgenic mice, and examined the effect of the mutation during the course of mouse development. In our test system, the ␥-globin gene is expressed at similar levels in the embryonic and adult erythroid cells. The TATA box mutation dramatically reduced expression of the ␥-globin gene in the adult but not in embryonic erythroid cells. In addition, the disruption of the ␥ TATA box significantly reduced the recruitment of TATA box-binding protein (TBP) in the adult cells, but not in embryonic cells, suggesting that the recruitment of TBP to the ␥ gene promoter is developmentally specific. Similarly, the recruitment of transcription factor II B and RNA polymerase II to the ␥ promoter was affected in the adult but not in embryonic cells. The distinct effects of the TATA mutation in the embryonic and adult developmental stages suggest that the basal transcription apparatus can be recruited to a core promoter in a developmental stage-dependent manner. The TATA mutation resulted in a shift of transcription initiation site 6 bp or longer upstream to the cap site both in the embryonic and adult erythrocytes. We conclude that the TATA box determines the initiation site but not the efficiency of transcription of the ␥-globin gene.