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Alternative splicing of the Menkes Copper Atpase (Atp7a) gene; regulation during iron‐deficiency
Author(s) -
Collins James F.,
Hua Ping,
Ranganathan P. N.
Publication year - 2008
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.22.1_supplement.443.7
Subject(s) - atp7a , exon , alternative splicing , biology , gene , splice , menkes disease , microbiology and biotechnology , rna splicing , transmembrane domain , genetics , chemistry , transporter , rna , copper metabolism , organic chemistry , copper
Atp7a is strongly induced during iron‐deficiency in rat intestine. The Atp7a gene is also induced in iron‐deprived IEC‐6 cells; actinomycin D treatment abolished this induction indicating transcriptional regulation. We thus sought to characterize the rat Atp7a gene promoter. We first identified the 5’ end of the Atp7a transcript. Results revealed 3 splice variants present at the 5’ end of the gene. All clones began with a sequence that mapped ~60 kb upstream of the rat Atp7a gene, which was homologous to exon 1 in mouse and human. We found that exon 1 was spliced to exon 1A (a novel exon), to exon 2 and to exon 3. The first 2 splice variants would encode a full length Atp7a protein, but the ex1/ex3 splice variant would encode a protein that was truncated by 69 amino acids (missing metal binding domain 1). Preliminary studies also suggest that these splice variants exist in mouse and human. A qRT‐PCR strategy was devised that allowed quantification of all 3 variants; results revealed ~7‐fold induction of all splice variants in the intestine of iron‐deficient rats. We further developed specific antibodies against the extreme N‐terminus of the rat Atp7a protein and showed strong induction of protein expression in iron‐deficient rats and unique immunolocalization in IEC‐6 cells. Our studies have thus revealed a novel variant of Atp7a that may display altered trafficking and function that could be important during iron‐deficiency.