Desmin Mutation in the C-Terminal Domain Impairs Traction Force Generation in Myoblasts

Abstract

The cytoskeleton plays a key role in the ability of cells to both resist mechanical stress and generate force, but the precise involvement of intermediate filaments in these processes remains unclear. We focus here on desmin, a type III intermediate filament, which is specifically expressed in muscle cells and serves as a skeletal muscle differentiation marker. By using several complementary experimental techniques, we have investigated the impact of overexpressing desmin and expressing a mutant desmin on the passive and active mechanical properties of C2C12 myoblasts. We first show that the overexpression of wild-type-desmin increases the overall rigidity of the cells, whereas the expression of a mutated E413K desmin does not. This mutation in the desmin gene is one of those leading to desminopathies, a subgroup of myopathies associated with progressive muscular weakness that are characterized by the presence of desmin aggregates and a disorganization of sarcomeres. We show that the expression of this mutant desmin in C2C12 myoblasts induces desmin network disorganization, desmin aggregate formation, and a small decrease in the number and total length of stress fibers. We finally demonstrate that expression of the E413K mutant desmin also alters the traction forces generation of single myoblasts lacking organized sarcomeres.

The desmin network is a determinant of the cytoplasmic stiffness of myoblasts

“…About 30% of the cells contain both a network and cytoplasmic aggregates of desmin. The features of this aggregation are specific to the E413K desmin mutation as previously described [Levin et al., ; Chourbagi et al., ; Charrier et al., ]. The presence of aggregates does not correlate with a high GFP signal: some very fluorescent cells do not show aggregates, whereas less fluorescent ones display aggregates, pointing out that the aggregation of desmin‐E413K‐GFP is not related to its over‐expression but to its dominant negative properties.…”

“…We focus here on the E413K mutation of desmin, a point mutation located at the beginning of the C‐terminal domain of the protein that disturbs its assembly into filaments in vitro [Bär et al., ; Levin et al., ], and leads to skeletal muscle weakness in patients [Pruszczyk et al., ]. We have recently shown that the expression of E413K‐mutated desmin in cellulo at the early stage of myoblasts alters these cells ability to generate traction forces [Charrier et al., ]. We question here the impact of this mutation on the viscoelastic properties of myoblasts.…”

Exome Sequencing Identifies a Novel <b><i>DES</i></b> Mutation (R227C) in a Chinese Dilated Cardiomyopathy Family

“…Desmin has multiple critical roles in muscle cells [9,13]. Previous research has confirmed that desmin plays a significant role in the organization and assembly of sarcomeres [14]; the first discovery of the DES mutation was made in desmin-related myofibrillar myopathy patients exhibiting a skeletal-muscle-restricted phenotype [8].…”

“…Desmin is expressed early in cardiac development, it is the major muscle-specific intermediate filament protein, and it is highly expressed in heart tissue [8,9,13]. Mutations in DES are highly capable of leading to heart disorders.…”

Condensed desmin and actin cytoskeletal communication in lipid droplets

“…To begin to understand intercytoskeletal communications, we focused on muscle desmin and actin, which are involved in force‐related events and in the scaffolding of the complex muscle architecture (Charrier et al, ; Leccia et al, ; Palmisano et al, ). The interaction of desmin filaments with muscle proteins of nebulin and nebulette contributes to the organization of the Z‐disk structure, and the modulation of their affinity by desmin mutations can induce dysfunction of striated muscle cells (Baker et al, ; Hernandez et al, ).…”