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bioRxiv · 10.1101/2021.02.03.429653

hC9ORF78 localizes to kinetochores and is required for proper chromosome segregation.

Koranne, R.·Brown, K.·Vandenbroek, H.·Taylor, W. R.
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Abstract

C9ORF78 is a poorly characterized protein found in diverse eukaryotes. Previous work indicated overexpression of hC9ORF78 (aka HCA59) in malignant tissues indicating a possible involvement in growth regulatory pathways. Additional studies in fission yeast and humans uncover a potential function in regulating the spliceosome. In studies of GFP-tagged hC9ORF78 we observed a dramatic reduction in protein abundance in cells grown to confluence and/or deprived of serum growth factors. Serum stimulation induced synchronous re-expression of the protein in HeLa cells. This effect was also observed with the endogenous protein. Overexpressing either E2F1 or N-Myc resulted in elevated hC9ORF78 expression potentially explaining the serum-dependent upregulation of the protein. Immunofluorescence analysis indicates that hC9ORF78 localizes to nuclei in interphase but does not appear to concentrate in speckles as would be expected for a splicing protein. Surprisingly, a subpopulation of hC9ORF78 co-localizes with ACA, Mad1 and Hec1 in mitotic cells suggesting that this protein may associate with kinetochores or centromeres. Furthermore, knocking-down hC9ORF78 caused mis-alignment of chromosomes in mitosis. These studies uncover novel mitotic function and subcellular localization of cancer antigen hC9ORF78. SUMMARY STATEMENThC9ORF78 regulates chromosome segregation.

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Koranne, R., Brown, K., Vandenbroek, H., Taylor, W. R.. 2021-02-03. hC9ORF78 localizes to kinetochores and is required for proper chromosome segregation.. https://doi.org/10.1101/2021.02.03.429653

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