Kirov N, Shtilbans A, Rushlow C
Department of Biology, New York University, 1009 Main Building, 100 Washington Square East, New York, NY 10003, USA.
Gene. 1998 Jun 8;212(2):323-32. doi: 10.1016/s0378-1119(98)00143-7.
The HIRA family of genes (named after yeast HIR genes; HIR is an acronym for 'histone regulator') includes the yeast HIR1 and HIR2 repressors of histone gene transcription in S. cerevisiae, human TUPLE-1/HIRA, chicken HIRA, and mouse HIRA. Here, we describe a new member of the HIRA family, Dhh, for the Drosophila homolog of HIRA . Northern analysis with poly (A)+ mRNA isolated from different developmental stages of Drosophila melanogaster shows hybridization with a single Dhh transcript of 4.1kb. Hybridization is strong in female adults, unfertilized eggs and 0-3-h-old embryos, then diminishes, but is still detectable, during later stages of development and in adult males. More specifically, in-situ hybridization shows that Dhh transcripts, which are initially detected in nurse cells during mid-oogenesis, become localized to the developing oocyte at high levels. Transcripts persist strongly during early blastoderm stages then fade dramatically by 3h of development. The Dhh cDNA encodes an open reading frame of 1061 amino acids with high similarity scores to the HIRA polypeptides, as well as two hypothetical polypeptides from C. elegans and S. pombe, in a protein database search. They all share three highly homologous regions: a WD-repeat cluster, a small domain with clustered positively charged amino acids, and a domain comprising two repeats with close resemblance to WD repeats plus a region with no homology outside of the family. The conservation of these homologous regions in HIRA-encoded proteins from evolutionary distant organisms suggests that they are important for the activity of the members of the family.
HIRA基因家族（以酵母HIR基因命名；HIR是“组蛋白调节因子”的首字母缩写）包括酿酒酵母中组蛋白基因转录的酵母HIR1和HIR2阻遏物、人类TUPLE-1/HIRA、鸡HIRA和小鼠HIRA。在此，我们描述了HIRA家族的一个新成员Dhh，它是果蝇中HIRA的同源物。用从黑腹果蝇不同发育阶段分离的聚腺苷酸加尾mRNA进行Northern分析，结果显示与一个4.1kb的单一Dhh转录本杂交。在成年雌性、未受精卵和0-3小时龄的胚胎中杂交信号很强，然后在发育后期和成年雄性中信号减弱，但仍可检测到。更具体地说，原位杂交显示，Dhh转录本最初在卵子发生中期的滋养细胞中被检测到，然后高水平地定位于发育中的卵母细胞。转录本在早期囊胚阶段持续强烈表达，然后在发育3小时后急剧消失。在蛋白质数据库搜索中，Dhh cDNA编码一个1061个氨基酸的开放阅读框，与HIRA多肽以及来自秀丽隐杆线虫和粟酒裂殖酵母的两个假定多肽具有高度相似性得分。它们都共享三个高度同源的区域：一个WD重复簇、一个带有成簇正电荷氨基酸的小结构域，以及一个包含两个与WD重复相似的重复序列加上一个家族外无同源性区域的结构域。这些同源区域在进化距离较远的生物体的HIRA编码蛋白中的保守性表明，它们对该家族成员的活性很重要。
