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.     

A Novel Zinc Finger Gene ZNF468 with Two Co-Expressional Splice Variants, ZNF468.1 and ZNF468.2

A novel human zinc finger protein encoding gene ZNF468 was obtained from a fetal brain cDNA library. By BLAST-N analysis we found two different splice variants. We termed the two splice variants ZNF468.1 and ZNF468.2. By BLAST search against the human genome database, ZNF468 was mapped to 19q13.4. The ZNF468.1 cDNA has four exons, and the ZNF468.2 cDNA has one more, between the third and fourth exon. This extra exon creates a difference between the deduced protein N-termini of the two splice variants. The ZNF468.1 cDNA is 3906 bp in length, encoding a 522a a protein, and ZNF468.2 is 4024 bp, encoding a 469-aa-protein. Both proteins contain 11 C2H2-type zinc finger motifs at their C-termini. The N-terminus of the deduced protein of ZNF468.1 has a well-conserved Krüppel-associated box (KRAB) domain that consists of KRAB boxes A and B, whereas the protein of ZNF468.2 does not have the {KRAB} domain. Tissue distribution of the ZNF468 gene indicates that the two splice variants are widely expressed in normal human tissues, except in heart and brain, and they are also co-expressional.     

Characterization of two novel KRAB-domain-containing zinc finger genes, ZNF460 and ZNF461, on human chromosome 19q13.1-->q13.4

This study reports the cloning and characterization of two novel human zinc finger protein cDNAs (ZNF460 and ZNF461) from a fetal brain cDNA library. The ZNF460 cDNA is 3,135 bp in length encoding a 562-amino-acid polypeptide and the ZNF461 cDNA is 2,548 bp encoding a 563-amino-acid protein. Both of the proteins contain a KRAB A+B box and eleven C2H2 type zinc finger motifs. ZNF461 shows high similarity with the rat GIOT-1 gene (GIOT1). The ZNF460 gene mapped to 19q13.4 with 3 exons, and ZNF461 mapped to 19q13.1 with 6 exons. Both of the two genes are ubiquitously expressed in normal human tissues and the abundance of the ZNF460 mRNA is relatively low.     

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.     

Cloning and characterization of a novel Krüppel-like zinc finger gene, ZNF268, expressed in early human embryo

With the aim of identifying genes involved in early human embryonic development, we have isolated a cDNA clone representing a novel human zinc finger gene ZNF268 from 3 week old human embryo cDNA library using a differential hybridization strategy. The complete cDNA sequence of ZNF268 contained an open reading frame of 2841 nucleotides that encodes a 947 amino acid protein with an N-terminal Krüppel-associated box (KRAB) domain and 24 C-terminal zinc fingers. Northern blot analysis showed that ZNF268 mRNA is mainly expressed in 3-5 week old human embryos suggesting it could play certain roles in the embryogenesis. The gene consists of six exons spanning about 22 kb of genomic DNA. According to the genomic sequence from the HTGS database, the ZNF268 gene is assigned to human chromosome 5.     

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.     

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。