title: The kinases LF4 and CNK2 control ciliary length by feedback regulation of assembly and disassembly rates.
abstract: BACKGROUND
  Many of the diverse functions of cilia depend upon tight control of their length. Steady-state length reflects a balance between rates of ciliary assembly and disassembly, two parameters likely controlled by a length sensor of unknown identity or mechanism.
  
  
  RESULTS
  A null mutation in Chlamydomonas CNK2, a member of the evolutionarily conserved family of NIMA-related kinases, reveals feedback regulation of assembly and disassembly rates. cnk2-1 mutant cells have a mild long-flagella (lf) phenotype as a consequence of reduced rates of flagellar disassembly. This is in contrast to the strong lf mutant lf4-7, which exhibits an aberrantly high rate of assembly. Cells carrying both mutations have even longer flagella than lf4-7 single mutants do. In addition to their high rate of assembly, lf4-7 mutants have a CNK2-dependent increase in disassembly rate. Finally, cnk2-1 cells have a decreased rate of turnover of flagellar subunits at the tip of the flagellum, demonstrating that the effects on disassembly are compensated by a reduced rate of assembly.
  
  
  CONCLUSIONS
  We propose a model wherein CNK2 and LF4 modulate rates of disassembly and assembly respectively in a feedback loop that is activated when flagella exceed optimal length.
authors.affiliation: Department of Molecular Biology and Biochemistry, Simon Fraser University, Burnaby, BC V5A 1S6, Canada.
authors.forename: Laura K
authors.initials: LK
authors.lastname: Hilton
authors.affiliation: Department of Molecular Biology and Biochemistry, Simon Fraser University, Burnaby, BC V5A 1S6, Canada.
authors.forename: Kavisha
authors.initials: K
authors.lastname: Gunawardane
authors.affiliation: Department of Molecular Biology and Biochemistry, Simon Fraser University, Burnaby, BC V5A 1S6, Canada.
authors.forename: Joo Wan
authors.initials: JW
authors.lastname: Kim
authors.affiliation: Department of Molecular Biology and Biochemistry, Simon Fraser University, Burnaby, BC V5A 1S6, Canada.
authors.forename: Marianne C
authors.initials: MC
authors.lastname: Schwarz
authors.affiliation: Department of Molecular Biology and Biochemistry, Simon Fraser University, Burnaby, BC V5A 1S6, Canada. Electronic address: quarmby@sfu.ca.
authors.forename: Lynne M
authors.initials: LM
authors.lastname: Quarmby
mesh_terms: D002696:Chlamydomonas / Q000166:cytology* / Q000235:genetics / Q000378:metabolism*; D002923:Cilia / Q000378:metabolism; D025461:Feedback, Physiological; D005407:Flagella / Q000235:genetics / Q000378:metabolism; D009154:Mutation; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D011494:Protein Kinases / Q000235:genetics / Q000378:metabolism*; D017346:Protein Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism*
chemical_list: D010940:Plant Proteins; D011494:Protein Kinases; C506116:Cnk2 protein, Chlamydomonas; D017346:Protein Serine-Threonine Kinases