Molecular control of centrosome copy number
Molecular control of centrosome copy number
Centrioles are microtubule-based structures that recruit a surrounding pericentriolar material to form the centrosome. Centrosomes nucleate the assembly of the microtubule cytoskeleton in interphase cells and form the poles of the mitotic spindle during cell division. Centriole duplication occurs once per cell cycle and is controlled by the conserved master regulator Polo-like kinase 4 (PLK4). Abnormal expression of PLK4 has been linked with tumorigenesis and drugs targeting PLK4 have recently entered clinical trials. Although significant progress has been made in understanding centriole composition, we do not understand how PLK4 activity controls specific steps in centriole formation. We showed that PLK4 kinase activity is controlled by binding to a protein called STIL that is found in the central part of the centriole. In addition, PLK4 phosphorylates its substrate STIL in two conserved regions to promote distinct binding interactions that together scaffold new centriole assembly. This provides a conceptual framework for understanding the control of centriole biogenesis and how this process can go awry in human tumors. Working with Andrew Goryachev’s lab, we incorporated what we learned from our studies on PLK4 to develop a mechanistic biophysical model for the initiation of centriole duplication.
Binding to Plk4 activated kinase activity to promote centriole duplication.
Moyer TC, Clutario KM, Lambrus BG, Daggubati V, Holland AJ. Journal of Cell Biology. 2015. Jun 22;209(6):863-78.
Autoamplification and competition drive symmetry breaking: Initiation of centriole duplication by the PLK4-STIL network.
Leda M, Holland AJ, Goryachev AB. iScience. 2018. Oct 11;8: 222-35.
Once and only once: mechanisms of centriole duplication and their deregulation in disease.
Nigg, E.A., Holland, A.J. Nature Reviews Molecular Cell Biology. 2018. 19(5): 297-312.
PLK4 promotes centriole duplication by phosphorylating STIL to link the procentriole to the microtubule wall.
Moyer, T.C. and Holland, A.J. eLIFE. 2019 8: e46054.
Mechanism and regulation of centriole and cilium biogenesis.
Breslow, D.K. and Holland, A.J. Ann Rev Biochem. 2019 88: 691-724.
WBP11 enables centriole biogenesis by mediating the splicing of TUBGCP6 pre-mRNA.
Park E, Scott PM, Clutario KM, Anglen T, Cassidy KB, Gerber SA, Holland AJ. Journal of Cell Biology. 2020. Jan 6:219.
centrosome amplification in cancer
The centrosome is the cell’s major microtubule-organizing center and plays an important role in mitosis, where it organizes the poles of the microtubule spindle apparatus that segregates the chromosomes. To maintain the fidelity of cell division, centrosome number must be strictly controlled. Cells begin the cycle with a single centrosome that duplicates only once to ensure cells have two copies of this organelle when they divide. This faithful control of centrosome number is deregulated in a wide array of tumor types, resulting in the acquisition of extra copies of centrosomes (referred to as centrosome amplification). Centrosome amplification causes mitotic errors in cultured cells that result in chromosome mis-segregation and chromosomal rearrangements. However, it remained untested whether supernumerary centrosomes actively drive tumorigenesis or whether they are simply a byproduct of cellular transformation. To address this important question in cancer biology, we created a mouse model in which centrosome amplification can be temporally induced at will. We showed that mice with extra centrosomes developed spontaneous tumors exhibiting widespread genomic instability, providing a causative link between centrosome amplification and tumorigenesis in mammals.
Centrosome amplification is sufficient to promote spontaneous tumorigenesis in mammals.
Levine, M.S., Bakker, B., Boeckx, B., Moyett, J., Lu, J., Vitre, B., Spierings, D.C., Lansdorp, P.M., Cleveland, D.W., Lambrechts, D., Foijer, F. and Holland, A.J. Developmental Cell. 2017. 40(3): 313-22.
The impact of mitotic errors on cell proliferation and tumorigenesis.
Levine, M.S., and Holland, A.J. Genes and Development. 2018. 32(9-10): 620-38.
The emerging link between centrosome aberrations and metastasis.
LoMastro, G.M. and Holland, A.J. Developmental Cell. 2019. 49(3): 325-31.
Targeting TRIM37-driven centrosome dysfunction in 17q23-amplified breast cancer.
Yeow, Z.Y.*, Lambrus, B.G.*, Marlow, R., Zhan, K.H., Durin, M., Evans, L.T., Scott, P.M., Phan, T., Park, E., Ruiz, L.A., Moralli, D., Knight, E.G., Badder, L.M., Novo, D., Haider, S., Green, C.M., Turr, A.N.J., Lord, C.J., Chapman, J.R.* and Holland, A.J.* Nature. 2020. 585(7824).
ANKRD26 recruits PIDD1 to distal appendages to activate the PIDDosome following centrosome amplification.
Evans, L.T., Anglen, T., Scott, P., Lukasik, K., Loncarek, J., Holland, A.J. EMBO J. In Press. 2020.
Centrosome defects in neural
Mitotic cells are susceptible to genomic alterations through the breakage or mis-segregation of chromosomes. Cells reduce the risk of these defects by carefully monitoring DNA integrity and chromosome attachments with quality-control checkpoints. Our recent identification of a signaling pathway that prevents proliferation following centrosome loss raised the question of how this pathway operates to preserve the integrity of mitosis. To address this question, we designed and executed a pooled genome-wide CRISPR-Cas9 screen to discover essential regulators of the cell cycle arrest caused by centrosome loss. This screen led to the identification of components of a new mitotic fail-safe, known as the mitotic surveillance pathway, which prevents the growth of cells in response to a prolonged mitosis. Importantly, centrosome loss activates this pathway by delaying spindle assembly and mitotic progression. We propose that an increased mitotic duration is recognized as a signal for the elimination of unfit cells that possess unresolved damage. Moreover, our recent work in this area shows that pathological activation of the mitotic surveillance pathway underlies the reduced brain growth in primary microcephaly, a neurodevelopmental disorder caused by mutations that affect centrosome function.
p53 protects against genome instability following centriole duplication failure.
Lambrus, B.G., Clutario, K.M., Daggubati, V., Snyder, M., Holland, A.J. Journal of Cell Biology. 2015. 210:63-77.
A USP28-53BP1-p53-p21 signaling axis arrests growth following centrosome loss or prolonged mitosis.
Lambrus, B.G., Daggubati, V., Uetake, Y., Scott, P.M., Clutario, K.M., Sluder, G., Holland, A.J. Journal of Cell Biology. 2016. 214:143-153.
Centrosome defects cause microcephaly by activating the mitotic surveillance pathway.
Phan, T., Maryniak, A., Boatwright, C.A., Lee, J., Atkins, A., Tijhuis, A., Spierings, D.C.J., Bazzi, H., Foijer, F., Jordan, P.W., Stracker, T.H., Holland, A.J. EMBO J. 2020. In Press.
CONTROL OF centriole number in multiciliated
Specialized multiciliated cells (MCCs) elaborate dense motile cilia that beat in a coordinated manner to drive fluid flow over epithelial surfaces. Defects in motile cilia formation or beating lead to fluid buildup in the brain, increased respiratory tract infections, and infertility. Centrioles reside at the base of each cilium and serve as a template for cilium assembly. In cycling cells, centriole formation is tightly controlled so that a single new procentriole forms adjacent to each of the two parent centrioles. However, MCCs deviate from this strict numerical control to produce hundreds of centrioles to serve as the foundation for building hundreds of motile cilia. Most of the centrioles amplified by MCCs develop on the surface of cell-type-specific organelles called deuterosomes, while a smaller number grow through the centriolar pathway in association with the two parent centrioles. The deuterosome organelle is thought to have evolved to control the massive production of centrioles.
We have interrogated the function of the deuterosome using a knockout mouse model. Surprisingly, our findings revealed that, in contrast to the current dogma, deuterosomes are dispensable for centriole amplification and multiciliogenesis. Moreover, MCCs lacking both parent centrioles and deuterosomes amplify the appropriatenumber of centrioles inside a cloud of pericentriolar material. This challenges the current thinking for how centriole amplification is controlled by showing that centriole number is set independently of their growing platforms in MCCs. We conclude that massive centriole production in MCCs is a robust process that relies on centriole self-assembly. While uncommon in mammals, this so-called de novo generation of centrioles has been observed in species such as the flatworm Planaria. We are now investigating how the centriole biogenesis machinery is tuned to control centriole assembly in MCCs.number of centrioles inside a cloud of pericentriolar material. This challenges the current thinking for how centriole amplification is controlled by showing that centriole number is set independently of their growing platforms in MCCs. We conclude that massive centriole production in MCCs is a robust process that relies on centriole self-assembly. While uncommon in mammals, this so-called de novo generation of centrioles has been observed in species such as the flatworm Planaria. We are now investigating how the centriole biogenesis machinery is tuned to control centriole assembly in MCCs.
Cell cycle proteins moonlight in multiciliogenesis.
Levine, M.S., and Holland, A.J. Science. 2017. 358(6364): 716-8.
Massive centriole production can occur in the absence of deuterosomes in multiciliated cells.
Mercey, O.*, Levine, M.S.*, LoMastro, G., Rostaing, P., Brotslaw, E., Gomez, V., Kumar, A., Spassky, N., Mitchell, B.J., Meunier, A.* and Holland, A.J.* Nature Cell Biology. 2019. 21: 1544-52. *equal contribution.