The KOX zinc finger genes: genome wide mapping of 368 ZNF PAC clones with zinc finger gene clusters predominantly in 23 chromosomal loci are confirmed by human sequences annotated in EnsEMBL

The chromosome locations of 368 human Kruppel-type zinc finger (ZNF) PAC clones were physically mapped by FISH to human chromosomes in support of recent efforts of assigning KOX cDNAs (KOX1-KOX32) to zinc finger gene clusters. Recent mapping results were validated and confirmed by sequence comparisons to zinc finger gene sequences automatically annotated in EnsEMBL. In toto, 799 Kruppel-type zinc finger genes have been annotated in EnsEMBL of which 290 genes are found to encode KRAB domains. Sequence homologies of the zinc finger domains were used to establish phylogenic trees of KOX zinc finger genes as well as of all KRAB containing human zinc finger and KOX genes documenting the evolution of KRAB zinc finger genes late in primate evolution. A list of 368 assigned ZNF PAC clones is available under http://www.pzr.uni-rostock.de/supplements.     

Isolation, characterization, and mapping of a novel human KRAB zinc finger protein encoding gene ZNF463

A novel human KRAB (Krüppel associated box) type zinc finger protein encoding gene, ZNF463, was obtained by mRNA differential display and RACE. It consists of 1904 nucleotides and encodes a protein of 463 amino acids with an amino-terminal KRAB domain and 12 carboxy-terminal C2H2 zinc finger units. The gene is mapped to chromosome 19q13.3 approximately 4 by FISH. As from Northern blot analysis ZNF463 is only expressed in testis, RT-PCR indicates that ZNF463 is expressed more highly in normal fertile adults than in fetus and azoospermic patients suggesting that it may play a role in human spermatogenesis.     

Assignment to chromosome 12q24.33, gene organization and splicing of the human KRAB/FPB containing zinc finger gene ZNF84

FISH analysis was used to assign the human ZNF84 gene to chromosome 12q24.33, a region associated with recurrent breakpoints and allelic loss in several human cancers. In this report we show that the ZNF84 coding region is organized in four exons; two are dedicated to encoding the KRAB/FPB-A and KRAB/FPB-B modules, the remaining exons encode the N-terminal amino acids and C-terminal array of zinc finger units, respectively.     

哺乳动物锌指蛋白家族中KRAB功能域的进化

KRAB锌指基因是哺乳动物中最大的转录调控因子家族,它的多数成员在基因组上成簇分布,具有五种不同的亚家族,在功能行使上承担着不同的作用。本文通过对人类、黑猩猩、小鼠、大鼠和狗五种哺乳动物全蛋白质组序列及mRNA组织表达谱分析,验证了C2H2锌指结构在单个KRAB蛋白质中出现的数目多于一般锌指蛋白质;KRAB功能域在各物种中分布显著不同且与分化时间不成正比,这表明KRAB相关功能域多样性在灵长类进化过程中潜在的适应性进化。同时,提出KRAB亚家族进化的路线：即KRAB—Aa为起始家族,Ba由Aa直接演变形成,而Ca,blonga和XRCC-Z种亚型可能经过Ba或直接从Aa演变形成;此外,锌指结构在单个蛋白质中出现个数伴随KRAB功能域自身的进化路线逐渐递增,反映了KRAB功能域在形成新转录调控因子方面的积极作用。     

Molecular cloning and preliminary functional analysis of two novel human KRAB zinc finger proteins, HKr18 and HKr19.

cDNA clones encoding two novel human KRAB zinc finger proteins, HKr18 and HKr19, were isolated from a human testis cDNA library. Their corresponding genes were later identified in sequences originating from chromosomes 19 and 7, respectively. On the basis of the collected information from gene and cDNA sequences, Hkr18 was found to be a protein of 94 kDa with 20 zinc finger motifs in its C terminus. The HKr19 is a smaller protein, with a molecular weight of 56 kDa containing 11 zinc finger motifs. Both HKr18 and HKr19 contained a KRAB A as well as a KRAB B domain in their N termini. Northern blot analysis showed expression of HKr18 in all human tissues tested, indicating a ubiquitous expression pattern. In contrast, HKr19 showed a more restricted tissue distribution, with detectable expression primarily in testis and fetal tissues. The HKr19 protein is a member of the large ZNF91 subfamily of KRAB zinc finger genes. A PCR-based analysis of the expression of HKr19 and other closely related genes showed that lymphoid, myeloid, and nonhematopoietic cells expressed different sets of these genes. This latter finding indicates that some members of the ZNF91 family may be involved in regulating lineage commitment during hematopoietic development. Transfection of various parts of HKr19 into human embryonic kidney cells (HEK 293 cells) showed that the entire protein and its zinc finger region were toxic to these cells when expressed at high levels. In contrast, the KRAB domain and the linker region seemed to be well tolerated.