Identification of a novel centrosome/microtubule-associated coiled-coil protein involved in cell-cycle progression and spindle organization.
Here we describe the identification of a novel vertebrate-specific centrosome/spindle pole-associated protein (CSPP) involved in cell-cycle regulation. The protein is predicted to have a tripartite domain structure, where the N- and C-terminal domains are linked through a coiled-coil mid-domain. Experimental analysis of the identified domains revealed that spindle association is dependent on the N-terminal and the coiled-coil mid domain. The expression of CSPP at the mRNA level was detected in all tested cell lines and in testis tissue. Ectopic expression of CSPP in HEK293T cells blocked cell-cycle progression in early G1 phase and in mitosis in a dose-dependent manner. Interestingly, mitosis-arrested cells contained aberrant spindles and showed impairment of chromosome congression. Inhibition of CSPP gene expression by small interfering RNAs induced cell-cycle arrest/delay in S phase. This phenotype was characterized by elevated levels of cyclin A, decreased levels of cyclin E and hyperphosphorylation of the S-phase checkpoint kinase Chk1. The activation of Chk1 may indicate a replication stress response due to an inappropriate G1/S-phase transition. Taken together, we demonstrate that CSPP is associated with centrosomes and microtubules and may play a role in the regulation of G(1)/S-phase progression and spindle assembly.
Patzke
Sebastian
S
Department of Immunology, The Norwegian Radium Hospital, Montebello, 0310 Oslo, Norway.
Hauge
Helena
H
Sioud
Mouldy
M
Finne
Eivind Farmen
EF
Sivertsen
Einar Andreas
EA
Delabie
Jan
J
Stokke
Trond
T
Aasheim
Hans-Christian
HC
D000595:Amino Acid Sequence; D000818:Animals; D002453:Cell Cycle / Q000235:genetics / Q000502:physiology*; D002460:Cell Line; D018385:Centrosome / Q000378:metabolism*; D005091:Exons / Q000235:genetics; D015870:Gene Expression; D006801:Humans; D008869:Microtubule-Associated Proteins / Q000032:analysis / Q000235:genetics / Q000502:physiology*; D008870:Microtubules / Q000737:chemistry / Q000378:metabolism; D008969:Molecular Sequence Data; D010766:Phosphorylation; D012333:RNA, Messenger / Q000032:analysis / Q000378:metabolism; D034741:RNA, Small Interfering / Q000235:genetics; D017386:Sequence Homology, Amino Acid; D012694:Serine / Q000378:metabolism; D008941:Spindle Apparatus / Q000378:metabolism* / Q000648:ultrastructure
D008869:Microtubule-Associated Proteins; D012333:RNA, Messenger; D034741:RNA, Small Interfering; D012694:Serine