Characterization of Bombyx mori mitochondrial transcription factor A, a conserved regulator of mitochondrial DNA

In the present study, we initially cloned and characterized a mitochondrial transcription factor A (Tfam) homologue in the silkworm, Bombyx mori. Bombyx mori TFAM (BmTFAM) localized to mitochondria in cultured silkworm and human cells, and co-localized with mtDNA nucleoids in human HeLa cells. In an...

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Bibliographic Details
Published in:Gene 2017-04, Vol.608, p.103-113
Main Authors: Sumitani, Megumi, Kondo, Mari, Kasashima, Katsumi, Endo, Hitoshi, Nakamura, Kaoru, Misawa, Toshihiko, Tanaka, Hiromitsu, Sezutsu, Hideki
Format: Article
Language:English
Subjects:
Amino Acid Sequence
Animals
Bombyx - embryology
Bombyx - genetics
Bombyx mori
Cells, Cultured
Cloning, Molecular
DNA, Mitochondrial - genetics
DNA-Binding Proteins - genetics
DNA-Binding Proteins - physiology
Embryonic RNAi
Gene Expression Regulation, Developmental
HeLa Cells
Humans
Mitochondria
Mitochondrial Proteins - genetics
Mitochondrial Proteins - physiology
mtDNA
Nucleoid
Sequence Analysis, DNA
TFAM
Transcription Factors - genetics
Transcription Factors - physiology
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Summary:In the present study, we initially cloned and characterized a mitochondrial transcription factor A (Tfam) homologue in the silkworm, Bombyx mori. Bombyx mori TFAM (BmTFAM) localized to mitochondria in cultured silkworm and human cells, and co-localized with mtDNA nucleoids in human HeLa cells. In an immunoprecipitation analysis, BmTFAM was found to associate with human mtDNA in mitochondria, indicating its feature as a non-specific DNA-binding protein. In spite of the low identity between BmTFAM and human TFAM (26.5%), the expression of BmTFAM rescued mtDNA copy number reductions and enlarged mtDNA nucleoids in HeLa cells, which were induced by human Tfam knockdown. Thus, BmTFAM compensates for the function of human TFAM in HeLa cells, demonstrating that the mitochondrial function of TFAM is highly conserved between silkworms and humans. BmTfam mRNA was strongly expressed in early embryos. Through double-stranded RNA (dsRNA)-based RNA interference (RNAi) in silkworm embryos, we found that the knockdown of BmTFAM reduced the amount of mtDNA and induced growth retardation at the larval stage. Collectively, these results demonstrate that BmTFAM is a highly conserved mtDNA regulator and may be a good candidate for investigating and modulating mtDNA metabolism in this model organism.
ISSN:0378-1119
1879-0038
DOI:10.1016/j.gene.2016.12.021