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The cooperative roles of PHO 80‐like cyclins in regulating the G 1/ S transition and posterior cytoskeletal morphogenesis in T rypanosoma brucei
Author(s) -
Liu Yi,
Hu Huiqing,
Li Ziyin
Publication year - 2013
Publication title -
molecular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.857
H-Index - 247
eISSN - 1365-2958
pISSN - 0950-382X
DOI - 10.1111/mmi.12352
Subject(s) - biology , microbiology and biotechnology , cytoskeleton , morphogenesis , cell , biochemistry , gene
Summary Cyclins and cyclin‐dependent kinases ( CDKs ) represent the fundamental, crucial regulators of the cell division cycle in eukaryotes. T rypanosoma brucei expresses a large number of cyclins and C dc 2‐ r elated k inases ( CRKs ). However, how these cyclins and CRKs cooperate to regulate cell cycle progression remains poorly understood. Here, we carry out directional yeast two‐hybrid assays to identify the interactions between the 10 cyclins and the 11 CRKs and detect a total of 26 cyclin– CRK pairs, among which 20 pairs are new. Our current efforts are focused on four PHO 80‐like cyclins, CYC 2, CYC 4, CYC 5 and CYC 7, and their physical and functional interactions with CRK 1. Silencing of the four cyclins and CRK 1 leads to the increase of G 1 cells and defective DNA replication, suggesting their important roles in promoting the G 1/ S transition. Additionally, CYC 2‐, CYC 7‐ and CRK 1‐deficient cells possess an elongated posterior that is filled with newly assembled microtubules. Further, we show that the four cyclins display distinct subcellular localizations and half‐lives, suggesting that they likely undergo distinct regulation. Altogether, our results demonstrate the involvement of four CRK 1‐associated cyclins, CYC 2, CYC 4, CYC 5 and CYC 7, in promoting the G 1/ S transition and the requirement of CYC 2 and CYC 7 in maintaining posterior cytoskeletal morphogenesis during the G 1/ S transition.