Opposites attract: Crosstalk between vimentin and microtubules - mechanical stability vs. dynamic adaptability

Project Information

CROSSTALK

Grant agreement ID: 101115795

DOI

10.3030/101115795

EC signature date 20 September 2023

Start date 1 January 2024

End date 31 December 2028

Funded under

• European Research Council (ERC)

Total cost

€ 1 499 990,00

EU contribution

€ 1 499 990,00

Coordinated by

UNIVERSITAT DES SAARLANDES
Germany

Periodic Reporting for period 1 - CROSSTALK (Opposites attract: Crosstalk between vimentin and microtubules - mechanical stability vs. dynamic adaptability)

Reporting period: 2024-01-01 to 2026-06-30

Summary of the context and overall objectives of the project

Living cells constantly face mechanical challenges. They change shape, migrate, divide, and withstand forces from their environment. To do this, they rely on an internal scaffold called the cytoskeleton. While two of its components — actin filaments and microtubules — have been extensively studied, much less is known about intermediate filaments, despite their crucial role in protecting cells from mechanically induced damage. Mutations in intermediate filament proteins are linked to human diseases, highlighting their physiological importance.
Among intermediate filaments, vimentin is the most widespread. It plays a key role in helping cells resist mechanical stress. However, we still lack a mechanistic understanding of how vimentin networks form, how they are organized inside cells, and how they cooperate with other cytoskeletal systems.
The project CROSSTALK addresses this knowledge gap. It is based on the hypothesis that vimentin and microtubules possess complementary mechanical and dynamic properties that together allow cells to combine two seemingly opposing features: mechanical stability and rapid adaptability. While microtubules are stiff and highly dynamic, vimentin filaments are soft and highly extensible. We propose that their coordinated organization enables cells to act both as resilient structures and as flexible, adaptive systems.
The overall objective of the project is to understand how the architecture of vimentin networks and their interaction with microtubules give rise to cellular mechanical resilience, while maintaining dynamic adaptability. To achieve this, the project investigates how composite filament networks are built, how they respond to mechanical stress, and how they reorganize, sustain damage, and recover.
Beyond advancing fundamental cytoskeletal research, the expected impact of this project is broader. Understanding how biological materials combine robustness with adaptability is a question that is relevant to a variety of biological systems across scales, where similar challenges arise, and thus points to a more general principle of living systems.

Work performed from the beginning of the project to the end of the period covered by the report and main results achieved so far

During the reporting period, CROSSTALK established experimental systems to investigate vimentin network formation and mechanics and to quantify microtubule responses to mechanical stress.
We developed a cell-extract-based reconstitution approach using multiple cell types and demonstrate that vimentin assembles into extended, cell-like networks in diverse mammalian extracts. Network architecture varies between cell types, while extracts from organisms lacking cytoplasmic intermediate filaments do not support network formation. These findings indicate that specific cytoplasmic components regulate vimentin assembly in a cell-type-dependent manner. In addition, we systematically linked network architecture to mechanical behavior by analyzing network fluctuations and varying filament length and density as well as availability of cytoplasmic components. Both structural parameters and cytoplasmic components modulate network mechanics, establishing a framework that connects organization with mechanics.
In parallel, we developed a controlled mechanical stress assay for microtubules using static bending and motor-driven buckling. This approach revealed substantial microtubule damage under sustained load and defined the limits of intrinsic self-repair, showing that microtubules require additional support structures to resist physiological mechanical stress. The assay provides an experimental platform to assess how different factors, such as a supporting vimentin network, influence microtubule mechanical stability.

Progress beyond the state of the art and expected potential impact (including the socio-economic impact and the wider societal implications of the project so far)

The results obtained so far suggest a conceptual shift in how intermediate filament networks are understood. Our observations indicate that vimentin network formation in cells may not be an autonomous self-assembly process driven solely by intrinsic filament properties. Instead, network architecture appears to be controlled by specific cytoplasmic co-factors that regulate filament assembly and organization.
Preliminary findings point to the existence of a regulatory layer in which accessory proteins influence filament formation and higher-order network structure. This suggests that cells may tune vimentin networks according to functional needs, rather than relying on passive self-organization. If confirmed, these findings would significantly expand the current view of intermediate filament biology, as vimentin networks would emerge as actively regulated, cell-type-specific systems. This would provide a mechanistic explanation for how cells adjust mechanical resilience and adaptability in different physiological contexts.
To ensure further progress, additional research is required to: (i) identify and characterize the regulatory factors involved; (ii) quantitatively link network architecture to mechanical performance depending on these factors; and (iii) integrate bottom-up reconstitution approaches with cell-based systems to validate physiological relevance.