Nucleic Acids Research, Vol 24, Issue 19 3846-3857, Copyright © 1996 by Oxford University Press
C Haigermoser, M Fujimoto, SM Iguchi-Ariga and H Ariga
MSSP proteins have been identified by their binding to an upstream element
of c-myc. Independently, two different approaches yielded two cDNA clones
highly homologous to the MSSP cDNAs, suggesting an involvement of MSSP in
the regulation of the cell cycle (scr2) and in the repression of HIV-1 and
ILR2 alpha-promoter transcription (human YC1). Screening human genomic
libraries, we have isolated clones belonging to two different gene loci.
Whereas the human MSSP gene 1 turned out to be intronless, the organization
of the coding sequence within gene 2 is more complex. It spans more than 60
kb and contains 16 exons (including two alternative first exons), ranging
from 48 to 287 bp, respectively. The intron sizes vary from 0.1 to more
than 13 kb. Gene 1 has been completely sequenced. A deletion series of its
upstream region was conjugated to the luciferase gene, but the transfection
of the constructs did not display any promoter activity. Moreover, compared
with gene 2 and the cDNA sequences known so far, about 20 point mutations
as well as flanking direct repeats have been detected in the MSSP gene 1,
showing that it possesses all the characteristics of processed
retropseudogenes. Sequence analysis of a 1.7 kb fragment of the 5' flanking
region of the MSSP gene 2 revealed that the promoter of gene 2 lacks
consensus sequences for TATA and CCAAT boxes, is GC- rich, and contains
numerous potential transcription factor binding elements including an Sp1
binding site. DNase I footprinting experiments showed that the putative Sp1
site was bound by proteins. The results of primer extension and S1 mapping
analyses suggested the transcription of the gene starts at multiple
positions upstream from the initiator methionine codon. Luciferase assays
employing progressive deletions of the 1.7 kb promoter region allowed us to
define the minimal promoter region of 428 bp (-488/+) and revealed a
complex pattern of the transcriptional regulation the human MSSP gene 2.
Furthermore, it can be concluded that the MSSP gene 2 encodes both MSSP- 1
and MSSP-2, and moreover scr2 and human YC1.
ARTICLES
Cloning and characterization of the genomic DNA of the human MSSP genes
Faculty of Pharmaceutical Sciences, Hokkaido University, Sapporo, Japan.
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