Doctor of Philosophy, Eidgenossische Technische Hochschule (ETH Zurich) (2011)
Master of Science, Eidgenossische Technische Hochschule (ETH Zurich) (2007)
Vordiplom, Philipps-Universitat Marburg/Lahn (2004)
Control of cell proliferation is a fundamental aspect of tissue formation in development and regeneration. Cells experience various spatial and mechanical constraints depending on their environmental context in the body, but we do not fully understand if and how such constraints influence cell cycle progression and thereby proliferation patterns in tissues. Here, we study the impact of mechanical manipulations on the cell cycle of individual cells within a mammalian model epithelium. By monitoring the response to experimentally applied forces, we find a checkpoint at the G1-S boundary that, in response to spatial constraints, controls cell cycle progression. This checkpoint prevents cells from entering S phase if the available space remains below a characteristic threshold because of crowding. Stretching the tissue results in fast cell cycle reactivation, whereas compression rapidly leads to cell cycle arrest. Our kinetic analysis of this response shows that cells have no memory of past constraints and allows us to formulate a biophysical model that predicts tissue growth in response to changes in spatial constraints in the environment. This characteristic biomechanical cell cycle response likely serves as a fundamental control mechanism to maintain tissue integrity and to ensure control of tissue growth during development and regeneration.
View details for DOI 10.1073/pnas.1323016111
View details for Web of Science ID 000334288600043
View details for PubMedID 24706777
The primary cilium is thought to be disassembled prior to mitosis, freeing the centrosomes to participate in the mitotic spindle. In this issue, Paridaen et al. demonstrate that a remnant of the ciliary membrane remains attached to the mother centriole and is asymmetrically inherited in the developing neocortex.
View details for DOI 10.1016/j.cell.2013.09.027
View details for PubMedID 24120128
Von Hippel-Lindau (VHL) tumor suppressor gene mutations predispose carriers to kidney cancer. The protein pVHL has been shown to interact with microtubules (MTs), which is critical to cilia maintenance and mitotic spindle orientation. However, the function for pVHL in the regulation of MT dynamics is unknown. We tracked MT growth via the plus end marker EB3 (end-binding protein 3)-GFP and inferred additional parameters of MT dynamics indirectly by spatiotemporal grouping of growth tracks from live cell imaging. Our data establish pVHL as a near-optimal MT-stabilizing protein: it attenuates tubulin turnover, both during MT growth and shrinkage, inhibits catastrophe, and enhances rescue frequencies. These functions are mediated, in part, by inhibition of tubulin guanosine triphosphatase activity in vitro and at MT plus ends and along the MT lattice in vivo. Mutants connected to the VHL cancer syndrome are differentially compromised in these activities. Thus, single cell-level analysis of pVHL MT regulatory function allows new predictions for genotype to phenotype associations that deviate from the coarser clinically defined mutant classifications.
View details for DOI 10.1083/jcb.201006059
View details for Web of Science ID 000282604600007
View details for PubMedID 20855504
Defects in the structure or function of the primary cilium, an antennae-like structure whose functional integrity has been linked to the suppression of uncontrolled kidney epithelial cell proliferation, are a common feature of genetic disorders characterized by kidney cysts. However, the mechanisms by which primary cilia are maintained remain poorly defined. von Hippel-Lindau (VHL) disease is characterized by the development of premalignant renal cysts and arises because of functional inactivation of the VHL tumour suppressor gene product, pVHL. Here, we show that pVHL and glycogen synthase kinase (GSK)3beta are key components of an interlinked signalling pathway that maintains the primary cilium. Although inactivation of either pVHL or GSK3beta alone did not affect cilia maintenance, their combined inactivation leads to loss of cilia. In VHL patients, GSK3beta is subjected to inhibitory phosphorylation in renal cysts, but not in early VHL mutant lesions, and these cysts exhibit reduced frequencies of primary cilia. We propose that pVHL and GSK3beta function together in a ciliary-maintenance signalling network, disruption of which enhances the vulnerability of cells to lose their cilia, thereby promoting cyst formation.
View details for DOI 10.1038/ncb1579
View details for Web of Science ID 000246181500018
View details for PubMedID 17450132