Structure and transcriptional regulation of human alpha-mannosidase IIX (alpha-mannosidase II isotype) gene.
Golgi alpha-mannosidase II is a key enzyme of N-glycan processing. Its genetic defect is associated with HEMPAS (hereditary erythroblastic multinuclearity with positive acidified serum lysis test). We previously cloned cDNAs of human alpha-mannosidase II (alpha-MII) and its isotype, alpha-mannosidase IIX [alpha-MIIX, Misago, M., Liao, Y. F., Eto, S., Mattei. M. G., Moremen. K. W. & Fukuda, M. N. (1995) Proc. Natl Acad. Sci. USA 92, 11766-11770]. Constitutive expressions of alpha-MII and alpha-MIIX mRNA were shown in various human tissues. To investigate the transcriptional regulation of alpha-MIIX gene, we characterized the cosmid clone of 40-kb that includes the 5'-flanking sequence. This clone contains at least eight exons which encode 396 amino acid residues of a total of 1139 amino acid residues of alpha-MIIX. Primer-extension analysis revealed multiple transcription-initiation sites in the range from -70 to -58 relative to the translation-initiation site. No canonical TATA or CAAT boxes were observed, but a (G + C)-rich region was found in close proximity to the transcription-initiation site. To localize the transcriptional regulatory region of this gene, various regions of the 5' sequences were fused to the luciferase gene, and transient-expression assays were conducted in human melanoma G-361 cells. These studies indicated that sequence from -12 to + 11 relative to the most distal 5'-transcription-initiation site was involved in the promoter function. Within this region, the sequence GGGCGT similar to the consensus sequence of the Sp1 binding site, is present at positions -12 to -7. Enhancer activities were found in the region upstream of this site, notably from -4300 to -252. Thus, the alpha-MIIX promoter located in a CpG island is also regulated by upstream elements, indicating the complexity of alpha-MIIX gene expression.
Ogawa
R
R
First Department of Internal Medicine, School of Medicine, University of Occupational and Environmental Health, Kitakyushu, Japan.
Misago
M
M
Fukuda
M N
MN
Kudo
S
S
Tsukada
J
J
Morimoto
I
I
Eto
S
S
D001482:Base Composition; D001483:Base Sequence; D002240:Carbohydrate Sequence; D015971:Gene Expression Regulation, Enzymologic; D005796:Genes; D006801:Humans; D008361:Mannosidases / Q000235:genetics*; D008969:Molecular Sequence Data; D011401:Promoter Regions, Genetic; D015183:Restriction Mapping; D014158:Transcription, Genetic; D014407:Tumor Cells, Cultured
D008361:Mannosidases; C038829:mannosyl-oligosaccharide 1,3 - 1,6-alpha-mannosidase