Invariant mRNA and mitotic protein breakdown solves the Russian Doll problem of the cell cycle.
It has been proposed that cyclical gene expression occurs at a large number of different times during the cell cycle. The existence of a large number of cycle-specific variations in mRNA and protein during the eukaryotic cell cycle raises the problem of how cell-cycle variations are regulated. This is the "infinite regression" or Russian Doll problem where postulating a cell-cycle specific control element pushes the explanation of cell-cycle variation back one step to the problem of how that control element varies during the cell cycle. PCR studies on unperturbed cells indicate Cyclin mRNA content is invariant during the cell cycle. Furthermore, calculations reveal that variations in mRNA content do not account for observed protein variations. Continuous and constant gene expression during the cell cycle, continuous protein accumulation, and protein breakdown only within the mitotic window solves the Russian Doll problem or infinite regression problem. These results, and theoretical ideas support an alternative view of the cell cycle where many of the proposed control systems do not exist.
Cooper
Stephen
S
Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, Michigan 48109-0520, USA. Cooper@Umich.Edu
Shedden
Kerby
K
Vu-Phan
Dang
D
D000818:Animals; D002453:Cell Cycle / Q000235:genetics*; D018797:Cell Cycle Proteins / Q000096:biosynthesis* / Q000235:genetics; D002455:Cell Division; D002460:Cell Line; D016213:Cyclins / Q000235:genetics / Q000378:metabolism; D005786:Gene Expression Regulation; D051379:Mice; D008938:Mitosis; D012333:RNA, Messenger / Q000032:analysis / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013997:Time Factors
D018797:Cell Cycle Proteins; D016213:Cyclins; D012333:RNA, Messenger