Collagen VI Deficiency Impairs Tendon Fibroblasts Mechanoresponse in Ullrich Congenital Muscular Dystrophy.

The pericellular matrix (PCM) is a specialized extracellular matrix that surrounds cells. Interactions with the PCM enable the cells to sense and respond to mechanical signals, triggering a proper adaptive response. Collagen VI is a component of muscle and tendon PCM. Mutations in collagen VI genes cause a distinctive group of inherited skeletal muscle diseases, and Ullrich congenital muscular dystrophy (UCMD) is the most severe form. In addition to muscle weakness, UCMD patients show structural and functional changes of the tendon PCM. In this study, we investigated whether PCM alterations due to collagen VI mutations affect the response of tendon fibroblasts to mechanical stimulation. By taking advantage of human tendon cultures obtained from unaffected donors and from UCMD patients, we analyzed the morphological and functional properties of cellular mechanosensors. We found that the length of the primary cilia of UCMD cells was longer than that of controls. Unlike controls, in UCMD cells, both cilia prevalence and length were not recovered after mechanical stimulation. Accordingly, under the same experimental conditions, the activation of the Hedgehog signaling pathway, which is related to cilia activity, was impaired in UCMD cells. Finally, UCMD tendon cells exposed to mechanical stimuli showed altered focal adhesions, as well as impaired activation of Akt, ERK1/2, p38MAPK, and mechanoresponsive genes downstream of YAP. By exploring the response to mechanical stimulation, for the first time, our findings uncover novel unreported mechanistic aspects of the physiopathology of UCMD-derived tendon fibroblasts and point at a role for collagen VI in the modulation of mechanotransduction in tendons.

Molecular characterization of ANKRD1 in rhabdomyosarcoma cell lines: expression, localization, and proteasomal degradation.

Rhabdomyosarcoma (RMS) is the most common soft tissue malignancy in children and adolescents. Respecting the age of the patients and the tumor aggressiveness, investigation of the molecular mechanisms of RMS tumorigenesis is directed toward the identification of novel therapeutic targets. To contribute to a better understanding of the molecular pathology of RMS, we investigated ankyrin repeat domain 1 (ANKRD1), designated as a potential marker for differential diagnostics. In this study, we used three RMS cell lines (SJRH30, RD, and HS-729) to assess its expression profile, intracellular localization, and turnover. They express wild-type ANKRD1, as judged by the sequencing of the open reading frame. Each cell line expressed a different amount of ANKRD1 protein, although the transcript level was similar. According to western blot analysis, ANKRD1 protein was expressed at detectable levels in the SJRH30 and RD cells (SJRH30 > RD), but not in the HS-729, even after immunoprecipitation. Immunocytochemistry revealed nuclear and cytoplasmic localization of ANKRD1 in all examined cell lines. Moreover, the punctate pattern of ANKRD1 staining in the nuclei of RD and HS-729 cells overlapped with coilin, indicating its association with Cajal bodies. We have shown that RMS cells are not able to overexpress ANKRD1 protein, which can be attributed to its proteasomal degradation. The unsuccessful attempt to overexpress ANKRD1 in RMS cells indicates the possibility that its overexpression may have detrimental effects for RMS cells and opens a window for further research into its role in RMS pathogenesis and for potential therapeutic targeting.

Desmin and Plectin Recruitment to the Nucleus and Nuclei Orientation Are Lost in Emery-Dreifuss Muscular Dystrophy Myoblasts Subjected to Mechanical Stimulation.

In muscle cells subjected to mechanical stimulation, LINC complex and cytoskeletal proteins are basic to preserve cellular architecture and maintain nuclei orientation and positioning. In this context, the role of lamin A/C remains mostly elusive. This study demonstrates that in human myoblasts subjected to mechanical stretching, lamin A/C recruits desmin and plectin to the nuclear periphery, allowing a proper spatial orientation of the nuclei. Interestingly, in Emery-Dreifuss Muscular Dystrophy (EDMD2) myoblasts exposed to mechanical stretching, the recruitment of desmin and plectin to the nucleus and nuclear orientation were impaired, suggesting that a functional lamin A/C is crucial for the response to mechanical strain. While describing a new mechanism of action headed by lamin A/C, these findings show a structural alteration that could be involved in the onset of the muscle defects observed in muscular laminopathies.

Antitumor activity of natural pigment violacein against osteosarcoma and rhabdomyosarcoma cell lines.

PURPOSE: Sarcomas are rare and heterogenic tumors with unclear etiology. They develop in bone and connective tissue, mainly in pediatric patients. To increase efficacy of current therapeutic options, natural products showing selective toxicity to tumor cells are extensively investigated. Here, we evaluated antitumor activity of bacterial pigment violacein in osteosarcoma (OS) and rhabdomyosarcoma (RMS) cell lines. METHODS: The toxicity of violacein was assessed in vitro and in vivo, using MTT assay and FET test. The effect of violacein on cell migration was monitored by wound healing assay, cell death by flow cytometry, uptake of violacein by fluorescence microscopy, generation of reactive oxygen species (ROS) by DCFH-DA assay and lipid peroxidation by TBARS assay. RESULTS: Violacein IC50 values for OS and RMS cells were in a range from 0.35 to 0.88 µM. Its selectivity toward malignant phenotype was confirmed on non-cancer V79-4 cells, and it was safe in vivo, for zebrafish embryos in doses up to 1 µM. Violacein induced apoptosis and affected the migratory potential of OS and RMS cells. It was found on the surfaces of tested cells. Regarding the mechanism of action, violacein acted on OS and RMS cells independently of oxidative signaling, as judged by no increase in intracellular ROS generation and no lipid peroxidation. CONCLUSION: Our study provided further evidence that reinforces the potential of violacein as an anticancer agent and candidate to consider for improvement of the effectiveness of traditional OS and RMS therapies.

The Ni(II)-Binding Activity of the Intrinsically Disordered Region of Human NDRG1, a Protein Involved in Cancer Development.

Nickel exposure is associated with tumors of the respiratory tract such as lung and nasal cancers, acting through still-uncharacterized mechanisms. Understanding the molecular basis of nickel-induced carcinogenesis requires unraveling the mode and the effects of Ni(II) binding to its intracellular targets. A possible Ni(II)-binding protein and a potential focus for cancer treatment is hNDRG1, a protein induced by Ni(II) through the hypoxia response pathway, whose expression correlates with higher cancer aggressiveness and resistance to chemotherapy in lung tissue. The protein sequence contains a unique C-terminal sequence of 83 residues (hNDRG1*C), featuring a three-times-repeated decapeptide, involved in metal binding, lipid interaction and post-translational phosphorylation. In the present work, the biochemical and biophysical characterization of unmodified hNDRG1*C was performed. Bioinformatic analysis assigned it to the family of the intrinsically disordered regions and the absence of secondary and tertiary structure was experimentally proven by circular dichroism and NMR. Isothermal titration calorimetry revealed the occurrence of a Ni(II)-binding event with micromolar affinity. Detailed information on the Ni(II)-binding site and on the residues involved was obtained in an extensive NMR study, revealing an octahedral paramagnetic metal coordination that does not cause any major change of the protein backbone, which is coherent with CD analysis. hNDRG1*C was found in a monomeric form by light-scattering experiments, while the full-length hNDRG1 monomer was found in equilibrium between the dimer and tetramer, both in solution and in human cell lines. The results are the first essential step for understanding the cellular function of hNDRG1*C at the molecular level, with potential future applications to clarify its role and the role of Ni(II) in cancer development.

Combined Treatment with PI3K Inhibitors BYL-719 and CAL-101 Is a Promising Antiproliferative Strategy in Human Rhabdomyosarcoma Cells.

Rhabdomyosarcoma (RMS) is a highly malignant and metastatic pediatric cancer arising from skeletal muscle myogenic progenitors. Recent studies have shown an important role for AKT signaling in RMS progression. Aberrant activation of the PI3K/AKT axis is one of the most frequent events occurring in human cancers and serves to disconnect the control of cell growth, survival, and metabolism from exogenous growth stimuli. In the study reported here, a panel of five compounds targeting the catalytic subunits of the four class I PI3K isoforms (p110α, BYL-719 inhibitor; p110ß, TGX-221 inhibitor; p110γ, CZC24832; p110δ, CAL-101 inhibitor) and the dual p110α/p110δ, AZD8835 inhibitor, were tested on the RMS cell lines RD, A204, and SJCRH30. Cytotoxicity, cell cycle, apoptosis, and the activation of downstream targets were analyzed. Of the individual inhibitors, BYL-719 demonstrated the most anti-tumorgenic properties. BYL-719 treatment resulted in G1/G0 phase cell cycle arrest and apoptosis. When combined with CAL-101, BYL-719 decreased cell viability and induced apoptosis in a synergistic manner, equaling or surpassing results achieved with AZD8835. In conclusion, our findings indicate that BYL-719, either alone or in combination with the p110δ inhibitor, CAL-101, could represent an efficient treatment for human rhabdomyosarcoma presenting with aberrant upregulation of the PI3K signaling pathway.

Early Morphological Changes of the Rectus Femoris Muscle and Deep Fascia in Ullrich Congenital Muscular Dystrophy.

Ullrich congenital muscular dystrophy (UCMD) is a severe form of muscular dystrophy caused by the loss of function of collagen VI, a critical component of the muscle-tendon matrix. Magnetic resonance imaging of UCMD patients' muscles shows a peculiar rim of abnormal signal at the periphery of each muscle, and a relative sparing of the internal part. The mechanism/s involved in the early fat substitution of muscle fiber at the periphery of muscles remain elusive. We studied a muscle biopsy of the rectus femoris/deep fascia (DF) of a 3-year-old UCMD patient, with a homozygous mutation in the COL6A2 gene. By immunohistochemical and ultrastructural analysis, we found a marked fatty infiltration at the interface of the muscle with the epimysium/DF and an atrophic phenotype, primarily in fast-twitch fibers, which has never been reported before. An unexpected finding was the widespread increase of interstitial cells with long cytoplasmic processes, consistent with the telocyte phenotype. Our study documents for the first time in a muscle biopsy the peculiar pattern of outside-in muscle degeneration followed by fat substitution as already shown by muscle imaging, and an increase of telocytes in the interstitium of the deep fascia, which highlights a potential involvement of this structure in the pathogenesis of UCMD.

Revisiting the Role of GSK3, A Modulator of Innate Immunity, in Idiopathic Inclusion Body Myositis.

Idiopathic or sporadic inclusion body myositis (IBM) is the leading age-related (onset >50 years of age) autoimmune muscular pathology, resulting in significant debilitation in affected individuals. Once viewed as primarily a degenerative disorder, it is now evident that much like several other neuro-muscular degenerative disorders, IBM has a major autoinflammatory component resulting in chronic inflammation-induced muscle destruction. Thus, IBM is now considered primarily an inflammatory pathology. To date, there is no effective treatment for sporadic inclusion body myositis, and little is understood about the pathology at the molecular level, which would offer the best hopes of at least slowing down the degenerative process. Among the previously examined potential molecular players in IBM is glycogen synthase kinase (GSK)-3, whose role in promoting TAU phosphorylation and inclusion bodies in Alzheimer's disease is well known. This review looks to re-examine the role of GSK3 in IBM, not strictly as a promoter of TAU and Abeta inclusions, but as a novel player in the innate immune system, discussing some of the recent roles discovered for this well-studied kinase in inflammatory-mediated pathology.

Ectopic Expression of Ankrd2 Affects Proliferation, Motility and Clonogenic Potential of Human Osteosarcoma Cells.

Ankrd2 is a protein known for being mainly expressed in muscle fibers, where it participates in the mechanical stress response. Since both myocytes and osteoblasts are mesenchymal-derived cells, we were interested in examining the role of Ankrd2 in the progression of osteosarcoma which features a mechano-stress component. Although having been identified in many tumor-derived cell lines and -tissues, no study has yet described nor hypothesized any involvement for this protein in osteosarcoma tumorigenesis. In this paper, we report that Ankrd2 is expressed in cell lines obtained from human osteosarcoma and demonstrate a contribution by this protein in the pathogenesis of this insidious disease. Ankrd2 involvement in osteosarcoma development was evaluated in clones of Saos2, U2OS, HOS and MG63 cells stably expressing Ankrd2, through the investigation of hallmark processes of cancer cells. Interestingly, we found that exogenous expression of Ankrd2 influenced cellular growth, migration and clonogenicity in a cell line-dependent manner, whereas it was able to improve the formation of 3D spheroids in three out of four cellular models and enhanced matrix metalloproteinase (MMP) activity in all tested cell lines. Conversely, downregulation of Ankrd2 expression remarkably reduced proliferation and clonogenic potential of parental cells. As a whole, our data present Ankrd2 as a novel player in osteosarcoma development, opening up new therapeutic perspectives.

Interleukin-6 neutralization ameliorates symptoms in prematurely aged mice.

Hutchinson-Gilford progeria syndrome (HGPS) causes premature aging in children, with adipose tissue, skin and bone deterioration, and cardiovascular impairment. In HGPS cells and mouse models, high levels of interleukin-6, an inflammatory cytokine linked to aging processes, have been detected. Here, we show that inhibition of interleukin-6 activity by tocilizumab, a neutralizing antibody raised against interleukin-6 receptors, counteracts progeroid features in both HGPS fibroblasts and LmnaG609G/G609G progeroid mice. Tocilizumab treatment limits the accumulation of progerin, the toxic protein produced in HGPS cells, rescues nuclear envelope and chromatin abnormalities, and attenuates the hyperactivated DNA damage response. In vivo administration of tocilizumab reduces aortic lesions and adipose tissue dystrophy, delays the onset of lipodystrophy and kyphosis, avoids motor impairment, and preserves a good quality of life in progeroid mice. This work identifies tocilizumab as a valuable tool in HGPS therapy and, speculatively, in the treatment of a variety of aging-related disorders.

Protein aggregates and autophagy involvement in a family with a mutation in Z-band alternatively spliced PDZ-motif protein.

Z-band alternatively spliced PDZ-motif protein (ZASP) is a sarcomeric component expressed both in cardiac and skeletal muscles. Mutations in the LDB3/ZASP gene cause cardiomyopathy and myofibrillar myopathy. We describe a c.76C>T / p.[Pro26Ser] mutation in the PDZ motif of LDB3/ZASP in two siblings exhibiting late-onset myopathy with axial, proximal and distal muscles involvement and marked variability in clinical severity in the absence of a significant family history for neuromuscular disorders. Notably, we identified involvement of the psoas muscle on MRI and muscle CT, a feature not previously documented. Proband's muscle biopsy showed an increase of ZASP expression by western blotting. Muscle fibres morphological features included peculiar sarcolemmal invaginations, pathological aggregates positive to ZASP, ubiquitin, p62 and LC3 antibodies, and the accumulation of autophagic vacuoles, suggesting that protein aggregate formation and autophagy are involved in this additional case of zaspopathy.

PCAF Involvement in Lamin A/C-HDAC2 Interplay during the Early Phase of Muscle Differentiation.

Lamin A/C has been implicated in the epigenetic regulation of muscle gene expression through dynamic interaction with chromatin domains and epigenetic enzymes. We previously showed that lamin A/C interacts with histone deacetylase 2 (HDAC2). In this study, we deepened the relevance and regulation of lamin A/C-HDAC2 interaction in human muscle cells. We present evidence that HDAC2 binding to lamina A/C is related to HDAC2 acetylation on lysine 75 and expression of p300-CBP associated factor (PCAF), an acetyltransferase known to acetylate HDAC2. Our findings show that lamin A and farnesylated prelamin A promote PCAF recruitment to the nuclear lamina and lamin A/C binding in human myoblasts committed to myogenic differentiation, while protein interaction is decreased in differentiating myotubes. Interestingly, PCAF translocation to the nuclear envelope, as well as lamin A/C-PCAF interaction, are reduced by transient expression of lamin A mutated forms causing Emery Dreifuss muscular dystrophy. Consistent with this observation, lamin A/C interaction with both PCAF and HDAC2 is significantly reduced in Emery-Dreifuss muscular dystrophy myoblasts. Overall, these results support the view that, by recruiting PCAF and HDAC2 in a molecular platform, lamin A/C might contribute to regulate their epigenetic activity required in the early phase of muscle differentiation.

Emerin Phosphorylation during the Early Phase of the Oxidative Stress Response Influences Emerin-BAF Interaction and BAF Nuclear Localization.

Reactive Oxygen Species (ROS) are reactive molecules required for the maintenance of physiological functions. Oxidative stress arises when ROS production exceeds the cellular ability to eliminate such molecules. In this study, we showed that oxidative stress induces post-translational modification of the inner nuclear membrane protein emerin. In particular, emerin is phosphorylated at the early stages of the oxidative stress response, while protein phosphorylation is abolished upon recovery from stress. A finely tuned balance between emerin phosphorylation and O-GlcNAcylation seems to govern this dynamic and modulates emerin-BAF interaction and BAF nucleoplasmic localization during the oxidative stress response. Interestingly, emerin post-translational modifications, similar to those observed during the stress response, are detected in cells bearing LMNA gene mutations and are characterized by a free radical generating environment. On the other hand, under oxidative stress conditions, a delay in DNA damage repair and cell cycle progression is found in cells from Emery-Dreifuss Muscular Dystrophy type 1, which do not express emerin. These results suggest a role of the emerin-BAF protein platform in the DNA damage response aimed at counteracting the detrimental effects of elevated levels of ROS.

Lamin A involvement in ageing processes.

Lamin A, a main constituent of the nuclear lamina, is the major splicing product of the LMNA gene, which also encodes lamin C, lamin A delta 10 and lamin C2. Involvement of lamin A in the ageing process became clear after the discovery that a group of progeroid syndromes, currently referred to as progeroid laminopathies, are caused by mutations in LMNA gene. Progeroid laminopathies include Hutchinson-Gilford Progeria, Mandibuloacral Dysplasia, Atypical Progeria and atypical-Werner syndrome, disabling and life-threatening diseases with accelerated ageing, bone resorption, lipodystrophy, skin abnormalities and cardiovascular disorders. Defects in lamin A post-translational maturation occur in progeroid syndromes and accumulated prelamin A affects ageing-related processes, such as mTOR signaling, epigenetic modifications, stress response, inflammation, microRNA activation and mechanosignaling. In this review, we briefly describe the role of these pathways in physiological ageing and go in deep into lamin A-dependent mechanisms that accelerate the ageing process. Finally, we propose that lamin A acts as a sensor of cell intrinsic and environmental stress through transient prelamin A accumulation, which triggers stress response mechanisms. Exacerbation of lamin A sensor activity due to stably elevated prelamin A levels contributes to the onset of a permanent stress response condition, which triggers accelerated ageing.

Tendon Extracellular Matrix Remodeling and Defective Cell Polarization in the Presence of Collagen VI Mutations.

Mutations in collagen VI genes cause two major clinical myopathies, Bethlem myopathy (BM) and Ullrich congenital muscular dystrophy (UCMD), and the rarer myosclerosis myopathy. In addition to congenital muscle weakness, patients affected by collagen VI-related myopathies show axial and proximal joint contractures, and distal joint hypermobility, which suggest the involvement of tendon function. To gain further insight into the role of collagen VI in human tendon structure and function, we performed ultrastructural, biochemical, and RT-PCR analysis on tendon biopsies and on cell cultures derived from two patients affected with BM and UCMD. In vitro studies revealed striking alterations in the collagen VI network, associated with disruption of the collagen VI-NG2 (Collagen VI-neural/glial antigen 2) axis and defects in cell polarization and migration. The organization of extracellular matrix (ECM) components, as regards collagens I and XII, was also affected, along with an increase in the active form of metalloproteinase 2 (MMP2). In agreement with the in vitro alterations, tendon biopsies from collagen VI-related myopathy patients displayed striking changes in collagen fibril morphology and cell death. These data point to a critical role of collagen VI in tendon matrix organization and cell behavior. The remodeling of the tendon matrix may contribute to the muscle dysfunction observed in BM and UCMD patients.

Ankrd2 in Mechanotransduction and Oxidative Stress Response in Skeletal Muscle: New Cues for the Pathogenesis of Muscular Laminopathies.

Ankrd2 (ankyrin repeats containing domain 2) or Arpp (ankyrin repeat, PEST sequence, and proline-rich region) is a member of the muscle ankyrin repeat protein family. Ankrd2 is mostly expressed in skeletal muscle, where it plays an intriguing role in the transcriptional response to stress induced by mechanical stimulation as well as by cellular reactive oxygen species. Our studies in myoblasts from Emery-Dreifuss muscular dystrophy 2, a LMNA-linked disease affecting skeletal and cardiac muscles, demonstrated that Ankrd2 is a lamin A-binding protein and that mutated lamins found in Emery-Dreifuss muscular dystrophy change the dynamics of Ankrd2 nuclear import, thus affecting oxidative stress response. In this review, besides describing the latest advances related to Ankrd2 studies, including novel discoveries on Ankrd2 isoform-specific functions, we report the main findings on the relationship of Ankrd2 with A-type lamins and discuss known and potential mechanisms involving defective Ankrd2-lamin A interplay in the pathogenesis of muscular laminopathies.

The Cutting Edge: The Role of mTOR Signaling in Laminopathies.

The mechanistic target of rapamycin (mTOR) is a ubiquitous serine/threonine kinase that regulates anabolic and catabolic processes, in response to environmental inputs. The existence of mTOR in numerous cell compartments explains its specific ability to sense stress, execute growth signals, and regulate autophagy. mTOR signaling deregulation is closely related to aging and age-related disorders, among which progeroid laminopathies represent genetically characterized clinical entities with well-defined phenotypes. These diseases are caused by LMNA mutations and feature altered bone turnover, metabolic dysregulation, and mild to severe segmental progeria. Different LMNA mutations cause muscular, adipose tissue and nerve pathologies in the absence of major systemic involvement. This review explores recent advances on mTOR involvement in progeroid and tissue-specific laminopathies. Indeed, hyper-activation of protein kinase B (AKT)/mTOR signaling has been demonstrated in muscular laminopathies, and rescue of mTOR-regulated pathways increases lifespan in animal models of Emery-Dreifuss muscular dystrophy. Further, rapamycin, the best known mTOR inhibitor, has been used to elicit autophagy and degradation of mutated lamin A or progerin in progeroid cells. This review focuses on mTOR-dependent pathogenetic events identified in Emery-Dreifuss muscular dystrophy, LMNA-related cardiomyopathies, Hutchinson-Gilford Progeria, mandibuloacral dysplasia, and type 2 familial partial lipodystrophy. Pharmacological application of mTOR inhibitors in view of therapeutic strategies is also discussed.

Mandibuloacral dysplasia: A premature ageing disease with aspects of physiological ageing.

Mandibuloacral dysplasia (MAD) is a rare genetic condition characterized by bone abnormalities including localized osteolysis and generalized osteoporosis, skin pigmentation, lipodystrophic signs and mildly accelerated ageing. The molecular defects associated with MAD are mutations in LMNA or ZMPSTE24 (FACE1) gene, causing type A or type B MAD, respectively. Downstream of LMNA or ZMPSTE24 mutations, the lamin A precursor, prelamin A, is accumulated in cells and affects chromatin dynamics and stress response. A new form of mandibuloacral dysplasia has been recently associated with mutations in POLD1 gene, encoding DNA polymerase delta, a major player in DNA replication. Of note, involvement of prelamin A in chromatin dynamics and recruitment of DNA repair factors has been also determined under physiological conditions, at the border between stress response and cellular senescence. Here, we review current knowledge on MAD clinical and pathogenetic aspects and highlight aspects typical of physiological ageing.

Emery-Dreifuss Muscular Dystrophy-Associated Mutant Forms of Lamin A Recruit the Stress Responsive Protein Ankrd2 into the Nucleus, Affecting the Cellular Response to Oxidative Stress.

BACKGROUND: Ankrd2 is a stress responsive protein mainly expressed in muscle cells. Upon the application of oxidative stress, Ankrd2 translocates into the nucleus where it regulates the activity of genes involved in cellular response to stress. Emery-Dreifuss Muscular Dystrophy 2 (EDMD2) is a muscular disorder caused by mutations of the gene encoding lamin A, LMNA. As well as many phenotypic abnormalities, EDMD2 muscle cells also feature a permanent basal stress state, the underlying molecular mechanisms of which are currently unclear. METHODS: Experiments were performed in EDMD2-lamin A overexpressing cell lines and EDMD2-affected human myotubes. Oxidative stress was produced by H2O2 treatment. Co-immunoprecipitation, cellular subfractionation and immunofluorescence analysis were used to validate the relation between Ankrd2 and forms of lamin A; cellular sensibility to stress was monitored by the analysis of Reactive Oxygen Species (ROS) release and cell viability. RESULTS: Our data demonstrate that oxidative stress induces the formation of a complex between Ankrd2 and lamin A. However, EDMD2-lamin A mutants were able to bind and mislocalize Ankrd2 in the nucleus even under basal conditions. Nonetheless, cells co-expressing Ankrd2 and EDMD2-lamin A mutants were more sensitive to oxidative stress than the Ankrd2-wild type lamin A counterpart. CONCLUSIONS: For the first time, we present evidence that in muscle fibers from patients affected by EDMD2, Ankrd2 has an unusual nuclear localization. By introducing a plausible mechanism ruling this accumulation, our data hint at a novel function of Ankrd2 in the pathogenesis of EDMD2-affected cells.