Biology subjects

van Breugel, M.

Publications and source records attributed to van Breugel, M..

3 recordsLinked to original sources

bioRxiv2026

Rotational asymmetry is required to position centrioles at the base of the primary cilium

The polarization of motile cilia requires that the centrioles, from which cilia are formed, display rotational asymmetry. This property is manifested in the presence of asymmetrically distributed appendages and relies on evolutionary conserved mechanisms. These mechanisms are also at play in cells that form primary cilia despite the lack of ciliary motility and asymmetric centriole appendages in this context. Here, we find that a complex consisting of CCDC61, KIAA1328 (K1328), and centlein (CNTLN) contributes to the establishment of centriole rotational asymmetry. In cells with a primary cilium, this complex is required for assembling a linker that repositions the daughter centriole close to and orthogonal to the proximal end of the mother centriole/basal body. The CCDC61/K1328/CNTLN complex also triggers the asymmetric recruitment of pericentriolar matrix components around newly assembled centrioles, which likely facilitates the later attachment of the basal body-daughter centriole linker. Overall, our results establish that rotational asymmetry relies on the coordinated recruitment of asymmetric landmarks along centrioles and is necessary for positioning the centrioles in a configuration that is widely conserved in ciliated cells.

cell biology↗

bioRxiv2024

Mesoscale regulation of MTOCs by the E3 ligase TRIM37

Centrosomes ensure accurate chromosome segregation during cell division. Although the regulation of centrosome number is well-established, less is known about the suppression of non-centrosomal MTOCs (ncMTOCs). The E3 ligase TRIM37, implicated in Mulibrey nanism and 17q23-amplified cancers, has emerged as a key regulator of both centrosomes and ncMTOCs. Yet, the mechanism by which TRIM37 achieves enzymatic activation to target these mesoscale structures had remained unknown. Here, we elucidate TRIM37s activation process, beginning with TRAF domain-directed substrate recognition, progressing through B-box domain-mediated oligomerization, and culminating in RING domain dimerization. Using optogenetics, we demonstrate that TRIM37s E3 activity is directly coupled to the assembly state of its substrates, activating only when centrosomal proteins cluster into higher-order assemblies resembling MTOCs. This regulatory framework provides a mechanistic basis for understanding TRIM37-driven pathologies and, by echoing TRIM5s restriction of the HIV capsid, unveils a conserved activation blueprint among TRIM proteins for controlling mesoscale assembly turnover.

molecular biology↗

bioRxiv2023

Tree demographic strategies largely overlap across succession in Neotropical wet and dry forest communities

Secondary tropical forests play an increasingly important role for carbon budgets and biodiversity conservation. Understanding successional trajectories is therefore imperative for guiding forest restoration and climate change mitigation efforts. Forest succession is driven by the demographic strategies - combinations of growth, mortality and recruitment rates - of the tree species in the community. However, our understanding of demographic diversity in tropical tree species stems almost exclusively from old-growth forests. Here, we assembled demographic information from repeated forest inventories along chronosequences in two wet (Costa Rica, Panama) and two dry (Mexico) Neotropical forests to assess whether the range of demographic strategies present in a community shifts across succession. We calculated demographic rates for >500 tree species while controlling for canopy status to compare demographic diversity in early successional (0-30 years), late successional (30-120 years) and old-growth forests. We quantified demographic diversity using two-dimensional hypervolumes of pairs of demographic rates and assessed whether shifts in demographic strategies were caused by intra-specific changes in demographic rates across succession or by species turnover. We expected that demographic strategies would shift from faster life-histories (fast growth, high mortality, high recruitment) in early successional forests to slower life histories (slow growth, low mortality, low recruitment) in old-growth forests and that shifts would be stronger in wet than in dry forests due to more pronounced differences in environmental conditions between early successional and old-growth forests. We also expected that demographic diversity would increase with succession. We found that demographic strategies largely overlapped across successional stages and that early successional stages already covered the full spectrum of demographic strategies found in old-growth forests. An exception was a group of species characterized by exceptionally high mortality rates that was confined to early successional stages in the two wet forests. Demographic diversity did not increase with succession. Our results suggest that current understanding of demographic strategies of tropical tree species, which has been generated mostly from long-term forest monitoring plots in old-growth forests, is largely representative of demographic diversity in general, and that demographic diversity recovers quickly during succession.

ecology↗