Nuclear Mechanics and Disease: Separate Lines of Evidence

This review retains descriptive findings from genetic case/family studies and defined mechanical cell models. The intact-cell lamin-A/C-null experiments connect lamins with nuclear deformation and selected signaling responses, while confined-migration imaging directly observes envelope rupture and repair. No clinical diagnostic or treatment conclusion is inferred. Lammerding et al. (2004); Denais et al. (2016).

Bonne et al. identified four LMNA variants co-segregating with autosomal-dominant Emery-Dreifuss muscular dystrophy in five families. Eriksson et al. reported recurrent LMNA G608G in 18 of 20 classical HGPS cases, activation of a cryptic splice site and a protein product lacking 50 amino acids. These findings are explicit in the primary abstracts; full pedigree and assay protocols were not appraised. Bonne et al. (1999); Eriksson et al. (2003).

The HGPS abstract also describes abnormal nuclear membranes in patient fibroblasts. That observation does not establish that every LMNA variant alters mechanics identically, or that a classical HGPS mechanism is the complete explanation for normal aging. Eriksson et al. (2003).

Lammerding et al. found increased deformation and fragility of lamin-A/C-null mouse fibroblast nuclei, with reduced viability under mechanical strain and altered induction of selected responsive genes. A complete-null mouse-cell comparison is not equivalent to every heterozygous human disease variant. Lammerding et al. (2004).

Stephens et al. separately found chromatin and lamin A/C contributions in different force-extension regimes of isolated nuclei. This supplies assay-specific component evidence, not a universal predictor of which patient tissue will fail. Stephens et al. (2017).

Denais et al. followed nuclear-localization reporters during confined migration in selected cancer-cell and skin-fibroblast models, with additional mouse-dermis xenograft imaging. Transient loss of nuclear compartmentalization and chromatin herniation were observed, and ESCRT-III machinery contributed to resealing. These are directly observed events in the tested settings. Denais et al. (2016).

The study also detected DNA-damage-associated signals during severe confinement. Such signals could appear without visible rupture, so the results do not establish rupture as the sole cause of damage or a universal explanation of human cancer progression. Denais et al. (2016).

In the lamin-A/C-null fibroblast experiments, strain-associated cell death and selected signaling defects were not accounted for solely by the small observed fraction of ruptured nuclei. Mechanical fragility and transcriptional response are related findings, but their co-occurrence does not resolve every tissue-specific laminopathy mechanism. Lammerding et al. (2004).

Familial LMNA co-segregation, patient fibroblast morphology and induced-confinement rupture have distinct samples and endpoints. Their combined relevance does not replace evidence connecting a particular human variant to a particular clinical outcome. Bonne et al. (1999); Eriksson et al. (2003); Denais et al. (2016).

The selected primary studies do not validate a mechanical screening test, diagnostic threshold or therapeutic effectiveness. Their supported contribution here is narrower: specified genetic findings, defined cell deformation/signaling phenotypes and observed rupture/repair during confinement. Bonne et al. (1999); Lammerding et al. (2004); Denais et al. (2016).

A disease-mechanism argument should keep human genetic evidence, preparation-specific mechanics, damage reporters and functional endpoints distinct. The checked studies establish important nuclear phenotypes in defined settings; they leave variant-specific causation and transfer to patient outcomes as questions requiring further evidence. Bonne et al. (1999); Eriksson et al. (2003); Lammerding et al. (2004); Denais et al. (2016).