Department of Biochemistry, University of Iowa, Carver College of Medicine, Iowa City, IA 52242, USA.
Nucleic Acids Res. 2010 Jan;38(3):846-58. doi: 10.1093/nar/gkp1062. Epub 2009 Nov 26.
Replication Protein A (RPA) is a single-stranded DNA-binding protein essential for DNA replication, repair, recombination and cell-cycle regulation. A human homolog of the RPA2 subunit, called RPA4, was previously identified and shown to be expressed in colon mucosal and placental cells; however, the function of RPA4 was not determined. To examine the function of RPA4 in human cells, we carried out knockdown and replacement studies to determine whether RPA4 can substitute for RPA2 in the cell. Unlike RPA2, exogenous RPA4 expression did not support chromosomal DNA replication and lead to cell-cycle arrest in G2/M. In addition, RPA4 localized to sites of DNA repair and reduced gamma-H2AX caused by RPA2 depletion. These studies suggest that RPA4 cannot support cell proliferation but can support processes that maintain the genomic integrity of the cell.
复制蛋白 A（RPA）是一种单链 DNA 结合蛋白，对 DNA 复制、修复、重组和细胞周期调控至关重要。先前已经鉴定出 RPA2 亚基的人类同源物，称为 RPA4，并在结肠黏膜和胎盘细胞中表达；然而，RPA4 的功能尚未确定。为了研究 RPA4 在人类细胞中的功能，我们进行了敲低和替换研究，以确定 RPA4 是否可以替代细胞中的 RPA2。与 RPA2 不同，外源性 RPA4 的表达不能支持染色体 DNA 复制，并导致细胞周期停滞在 G2/M 期。此外，RPA4 定位于 DNA 修复部位，并减少了由 RPA2 耗竭引起的 γ-H2AX。这些研究表明，RPA4 不能支持细胞增殖，但可以支持维持细胞基因组完整性的过程。
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