Mechanics in human fibroblasts and progeria: Lamin A mutation E145K results in stiffening of nuclei

Abstract

The lamina is a filamentous meshwork beneath the inner nuclear membrane that confers mechanical stability to nuclei. The E145K mutation in lamin A causes Hutchinson-Gilford progeria syndrome (HGPS). It affects lamin filament assembly and induces profound changes in the nuclear architecture. Expression of wild-type and E145K lamin A in Xenopus oocytes followed by atomic force microscopy (AFM) probing of isolated oocyte nuclei has shown significant changes in the mechanical properties of the lamina. Nuclei of oocytes expressing E145K lamin A are stiffer than those expressing wild-type lamin A. Here we present mechanical measurements by AFM on dermal fibroblasts obtained from a 4-year-old progeria patient bearing the E145K lamin A mutation and compared it to fibroblasts obtained from 2 healthy donors of 10 and 61 years of age, respectively. The abnormal shape of nuclei expressing E145K lamin A was analyzed by fluorescence microscopy. Lamina thickness was measured using electron micrographs. Fluorescence microscopy showed alterations in the actin network of progeria cells. AFM probing of whole dermal fibroblasts did not demonstrate significant differences in the elastic moduli of nuclear and cytoplasmic cell regions. In contrast, AFM measurements of isolated nuclei showed that nuclei of progeria and old person's cells are significantly stiffer than those of the young person, indicating that the process of aging, be it natural or abnormal, increases nuclear stiffness. Our results corroborate AFM data obtained using Xenopus oocyte nuclei and prove that the presence of E145K lamin A abnormally increases nuclear stiffness.

Nonlinear mechanics of lamin filaments and the meshwork topology build an emergent nuclear lamina

“…It is therefore important to understand the underlying principles of lamin mechanics in health and disease 20,21 . Intact nuclei of X. laevis oocytes 22 and human fibroblasts were previously probed mechanically using the atomic force microscope (AFM) 23,24 to understand the role of lamina in nuclear mechanics. Micropipette aspiration has successfully provided deformation characteristics of nuclei and the NE 25, 26 .…”

Fifteen years of Servitude et Grandeur to the application of a biophysical technique in medicine: The tale of AFMBioMed

“…A virtual issue appeared in the Journal of Molecular Recognition in 2017 . Nine research articles composed this special issue . At the end of the conference, it was announced that the next one will be organized in Kraków, in 2017.…”

“…[48][49][50][51][52][53][54][55][56][57] The last change that was made during the 75 Nine research articles composed this special issue. [76][77][78][79][80][81][82][83][84] At the end of the conference, it was announced that the next one will…”

A Perspective on the Experimental Techniques for Studying Lamins

“…The E145K mutant form of lamin A, which is associated with the Hutchinson-Gilford progeria syndrome (HGPS) was shown to increase the nuclear stiffness not only in Xenopus oocytes [ 17 ], but also in dermal fibroblasts from a 4-year old HGPS patient, when compared to those from a 10-year old healthy donor [ 44 ]. In both cases, TEM imaging did not display significant differences in NE thickness between mutants and controls.…”