Maintaining genome integrity at cell division
Cullin4A-RING E3 ubiquitin ligases (CRL4s) are protein complexes that play an important role during DNA replication, chromosome segregation and controlled protein breakdown to ensure genome integrity. During mitosis, post-translational modifications such as ubiquitination (addition of ubiquitin molecule fragments) play a key role in protein regulation and localisation. The project 'Function and regulation of CRL4s-based ubiquitin-dependent processes for mitotic progression' (JM_ETHZ_IEF_2009) was initiated to study how CRL4s regulate mitotic processes in our cells. In particular they looked at enzymes involved in the ubiquitination process. Researchers carried out automated high-content live cell imaging with RNAi-based screen using advanced microscopy. This permitted the monitoring of individual cells throughout the cell cycle and helped in the identification of CRL4 substrate adaptors. Two promising candidates were subjected to comprehensive functional and biochemical analysis. Study results revealed that one of these acted on motor proteins and helped regulate chromosome congression during mitosis. The other candidate ensured accurate chromosome alignment during kinetochore formation and establishment in mitosis. The kinetochore is a protein complex that acts as attachment sites for spindle microtubules during mitosis to properly align chromosomes. Project activities have demonstrated that CRL4s play an important role in regulating mitosis and ensuring error-free progression through ubiquitination of key proteins. Future research activities could focus on pinpointing the physiological substrates of these adaptors. This work would be of huge significance in diagnosing and developing gene-based therapies for diseases like cancer and genetic disorders.
Keywords
CRL4, genome integrity, mitotic, cell cycle, cancer, ubiquitin, chromosome, proteolysis, substrate adaptor, kinetochore, genetic disorder