The laminin–keratin link shields the nucleus from mechanical deformation and signalling

The mechanical properties of the extracellular matrix dictate tissue behaviour. In epithelial tissues, laminin is a very abundant extracellular matrix component and a key supporting element. Here we show that laminin hinders the mechanoresponses of breast epithelial cells by shielding the nucleus from mechanical deformation. Coating substrates with laminin-111—unlike fibronectin or collagen I—impairs cell response to substrate rigidity and YAP nuclear localization. Blocking the laminin-specific integrin β4 increases nuclear YAP ratios in a rigidity-dependent manner without affecting the cell forces or focal adhesions. By combining mechanical perturbations and mathematical modelling, we show that β4 integrins establish a mechanical linkage between the substrate and keratin cytoskeleton, which stiffens the network and shields the nucleus from actomyosin-mediated mechanical deformation. In turn, this affects the nuclear YAP mechanoresponses, chromatin methylation and cell invasion in three dimensions. Our results demonstrate a mechanism by which tissues can regulate their sensitivity to mechanical signals.

-Accession codes, unique identifiers, or web links for publicly available datasets -A description of any restrictions on data availability -For clinical datasets or third party data, please ensure that the statement adheres to our policy Values used to generate the graphs of this manuscript are available at https://doi.org/10.34810/data747Field-specific reporting Please select the one below that is the best fit for your research.If you are not sure, read the appropriate sections before making your selection.

Life sciences
Behavioural & social sciences Ecological, evolutionary & environmental sciences For a reference copy of the document with all sections, see nature.com/documents/nr-reporting-summary-flat.pdf

Life sciences study design
All studies must disclose on these points even when the disclosure is negative.

Sample size
Sample size was calculated based on previous experiments and pilot experiments.
Data exclusions No data were excluded.

Replication
Data were replicated at least 3 times for most experiments and 2 times for the ones listed in the manuscript, obtaining similar results.The number for the repeats is stated for each data set.
Randomization All allocations and measurements were random.
Blinding 2 people performed experiments and data analysis for integrin beta4 mutant versus control YAP nuclear ratios.No experiment was blinded, because the same investigator performed and analyzed the data.Analysis of TFM, AFM, optical tweezers, actin anisotropy, nuclear shapes, fluorescence intensity, actin-keratin distribution and flow experiments are not blinded since they cannot be influenced by the subjected judgment of the examiner.
Behavioural & social sciences study design All studies must disclose on these points even when the disclosure is negative.

Study description
Briefly describe the study type including whether data are quantitative, qualitative, or mixed-methods (e.g.qualitative cross-sectional, quantitative experimental, mixed-methods case study).

Research sample
State the research sample (e.g.Harvard university undergraduates, villagers in rural India) and provide relevant demographic information (e.g.age, sex) and indicate whether the sample is representative.Provide a rationale for the study sample chosen.For studies involving existing datasets, please describe the dataset and source.

Sampling strategy
Describe the sampling procedure (e.g. random, snowball, stratified, convenience).Describe the statistical methods that were used to predetermine sample size OR if no sample-size calculation was performed, describe how sample sizes were chosen and provide a rationale for why these sample sizes are sufficient.For qualitative data, please indicate whether data saturation was considered, and what criteria were used to decide that no further sampling was needed.

Data collection
Provide details about the data collection procedure, including the instruments or devices used to record the data (e.g.pen and paper, computer, eye tracker, video or audio equipment) whether anyone was present besides the participant(s) and the researcher, and whether the researcher was blind to experimental condition and/or the study hypothesis during data collection.

Timing
Indicate the start and stop dates of data collection.If there is a gap between collection periods, state the dates for each sample cohort.

Data exclusions
If no data were excluded from the analyses, state so OR if data were excluded, provide the exact number of exclusions and the rationale behind them, indicating whether exclusion criteria were pre-established.

Non-participation
State how many participants dropped out/declined participation and the reason(s) given OR provide response rate OR state that no participants dropped out/declined participation.

Ecological, evolutionary & environmental sciences study design
All studies must disclose on these points even when the disclosure is negative.

Study description
Briefly describe the study.For quantitative data include treatment factors and interactions, design structure (e.g.factorial, nested, hierarchical), nature and number of experimental units and replicates.

Sampling strategy
Note the sampling procedure.Describe the statistical methods that were used to predetermine sample size OR if no sample-size calculation was performed, describe how sample sizes were chosen and provide a rationale for why these sample sizes are sufficient.

Data collection
Describe the data collection procedure, including who recorded the data and how.
Timing and spatial scale Indicate the start and stop dates of data collection, noting the frequency and periodicity of sampling and providing a rationale for these choices.If there is a gap between collection periods, state the dates for each sample cohort.Specify the spatial scale from which the data are taken

Data exclusions
If no data were excluded from the analyses, state so OR if data were excluded, describe the exclusions and the rationale behind them, indicating whether exclusion criteria were pre-established.

Reproducibility
Describe the measures taken to verify the reproducibility of experimental findings.For each experiment, note whether any attempts to repeat the experiment failed OR state that all attempts to repeat the experiment were successful.

Randomization
Describe how samples/organisms/participants were allocated into groups.If allocation was not random, describe how covariates were controlled.If this is not relevant to your study, explain why.

Blinding
Describe the extent of blinding used during data acquisition and analysis.If blinding was not possible, describe why OR explain why blinding was not relevant to your study.

Did the study involve field work?
Yes No Field work, collection and transport

Field conditions
Describe the study conditions for field work, providing relevant parameters (e.g.temperature, rainfall).

Location
State the location of the sampling or experiment, providing relevant parameters (e.g.latitude and longitude, elevation, water depth).
Access & import/export Describe the efforts you have made to access habitats and to collect and import/export your samples in a responsible manner and in compliance with local, national and international laws, noting any permits that were obtained (give the name of the issuing authority, the date of issue, and any identifying information).

Disturbance
Describe any disturbance caused by the study and how it was minimized.

Reporting for specific materials, systems and methods
We require information from authors about some types of materials, experimental systems and methods used in many studies.Here, indicate whether each material, system or method listed is relevant to your study.If you are not sure if a list item applies to your research, read the appropriate section before selecting a response.