During myogenic differentiation, the Microtubule-Organizing Center (MTOC) is relocated to the nuclear envelope by a molecular platform including Linker of Nucleoskeleton and Cytoskeleton (LINC) complex proteins, A Kinase Anchoring Proteins (AKAP9 and AKAP6) and Pericentriolar Material 1 (PCM-1). Here, we show that emerin is required for centrosomal protein recruitment to the nuclear periphery of myonuclei and microtubule dynamics. In fact, in type 1 Emery-Dreifuss Muscular Dystrophy (EDMD1), loss of emerin was associated with altered pericentrin recruitment to the nuclear envelope, LINC protein impairment at the nuclear poles of myonuclei and microtubule organization defects. As a consequence, dynein, mitochondrial distribution and nuclear alignment along the longitudinal axis of the myotubes were altered in EDMD1 myotubes. Moreover, reduced levels of AKAP6 and PKA were detected at the nuclear periphery of EDMD1 myotubes, possibly contributing to an aberrant nuclear localization of the mechanosensing factor YAP. Upon rescue of emerin expression by CRISPR correction of mutated EMD gene: SUN1/2, pericentrin, AKAP6 and PKA were restored at the nuclear envelope and a correct YAP localization was observed in EDMD1 muscle cells. These results show that emerin is required for Nuclear Envelope-MTOC (NE-MTOC) organization in differentiating skeletal muscle cells and suggest that disruption of such complex is a key pathogenetic event in Emery-Dreifuss Muscular Dystrophy.

Il tessuto adiposo è un organo complesso deputato all’immagazzinamento energetico (tessuto adiposo bianco), alla produzione di energia (tessuto adiposo bruno), alla protezione meccanica degli organi e al rilascio di ormoni e citochine. La caratteristica principale del tessuto adiposo è probabilmente la sua plasticità, dovuta alla capacità degli adipociti di passare da un fenotipo all’altro in processi noti come browning o whitening, nonché di aumentare o diminuire la propria massa attivando l’ipertrofia o la lipolisi. Ciò che accade nelle lipodistrofie è la progressiva perdita di tale plasticità e l’insorgenza di una condizione patogenetica che porta a una perdita di grasso progressiva e irreversibile. Tale perdita di grasso può verificarsi in tutto il corpo o può risparmiare alcuni depositi, come avviene nelle lipodistrofie parziali. Tuttavia, i meccanismi alla base della disfunzione del tessuto adiposo sono ancora poco noti. I nostri dati recenti mostrano che il differenziamento aberrante degli adipociti bruni verso la linea bianca è alla base dell’accumulo di tessuto adiposo nel collo nella lipodistrofia parziale familiare di tipo Dunnigan (tipo 2) e che il meccanismo è associato al reclutamento del recettore dei mineralcorticoidi nel nucleo dei preadipociti bruni, che tendono quindi a differenziarsi in modo aberrante verso la linea bianca. Questi risultati sono coerenti con il legame del recettore dei mineralcorticoidi alla lamina A, la proteina dell’involucro nucleare mutata nella lipodistrofia parziale familiare di tipo 2, e suggeriscono che l’antagonismo del recettore dei mineralcorticoidi possa rivelarsi utile nel trattamento dei pazienti. Tuttavia, suggeriamo che il problema centrale da affrontare nello studio delle lipodistrofie sia il disaccoppiamento del rimodellamento del tessuto adiposo dalle condizioni ambientali, inclusi stimoli ormonali, nutrizionali, meccanici e da freddo. La conoscenza di tale meccanismo potrebbe fornire strumenti terapeutici in grado di recuperare i depositi di tessuto adiposo persi nelle lipodistrofie.

Historically considered downstream effects of tumorigenesis-arising from changes in DNA content or chromatin organization-nuclear alterations have long been seen as mere prognostic markers within a genome-centric model of cancer. However, recent findings have placed the nuclear envelope (NE) at the forefront of tumor progression, highlighting its active role in mediating cellular responses to mechanical forces. Despite significant progress, the precise interplay between NE components and cancer progression remains under debate. In this review, we provide a comprehensive and up-to-date overview of how changes in NE composition affect nuclear mechanics and facilitate malignant transformation, grounded in the latest molecular and functional studies. We also review recent research that uses advanced technologies, including artificial intelligence, to predict malignancy risk and treatment outcomes by analyzing nuclear morphology. Finally, we discuss how progress in understanding nuclear mechanics has paved the way for mechanotherapy-a promising cancer treatment approach that exploits the mechanical differences between cancerous and healthy cells. Shifting the perspective on NE alterations from mere diagnostic markers to potential therapeutic targets, this review calls for further investigation into the evolving role of the NE in cancer, highlighting the potential for innovative strategies to transform conventional cancer therapies.

OBJECTIVE:Lipodystrophy syndromes comprise a group of rare diseases characterized by loss of adipose tissue without nutritional or catabolic causes. As the rarity of these conditions necessitates collaboration, the European Consortium of Lipodystrophies (ECLip) established an international, longitudinal registry for patients with all forms of lipodystrophy (excluding HIV-associated cases). METHODS:From December 2017 to November 2023, 19 centers from 13 countries recruited 631 patients into the ECLip Registry. Cross-sectional data were analyzed using descriptive statistics. RESULTS:Prospective data were available for 467 patients (82.7% female; 86.5% adults; median age 44.0 years). Familial partial lipodystrophy (FPLD) was the most common subtype (57.4%), especially FPLD2 (37.9%). However, in men, congenital generalized lipodystrophy was nearly as common as FPLD (33.3% vs. 35.8%). Symptoms at onset varied by subtype, with loss of adipose tissue being the most frequent. More than 70% of the patients suffered from metabolic complications, particularly dyslipidemia (59.0%) and diabetes (48.4%), but prevalence and severity varied between subtypes (prevalence of diabetes, eg, 76.9% in patients with acquired partial lipodystrophy vs. 8.7% in acquired localized lipodystrophy). Metreleptin, the only disease-specific treatment, was used by 11.6% of all patients. Thirty-four deaths were documented, primarily due to cardiovascular events and cancer. Patients with generalized forms of lipodystrophy died earlier compared to patients with partial forms (median age at death 27.0 vs. 72.0 years). CONCLUSION:This study describes the largest cohort of patients with lipodystrophy reported to date. The dataset offers a comprehensive view of the epidemiology, clinical presentation, and associated comorbidities of lipodystrophy.

Emery–Dreifuss muscular dystrophy (EDMD) is caused by mutations in EMD, LMNA, SYNE1, SYNE2, and other related genes. The disease is characterized by joint contractures, muscle weakening and wasting, and heart conduction defects associated with dilated cardiomyopathy. Previous studies demonstrated the activation of fibrogenic molecules such as TGFbeta 2 and CTGF in preclinical models of EDMD2 and increased secretion of TGFbeta 2 in patient serum. A wide screening of patient cells suggested fibrosis, metabolism, and myogenic signaling as the most affected pathways in various EDMD forms. In this study, we show that alpha-smooth muscle actin-positive myofibroblasts are overrepresented in patient fibroblast cultures carrying EMD, LMNA, or SYNE2 mutations, and profibrotic miRNA-21 is upregulated. Upon CRISPR/Cas correction of the mutated EMD or LMNA sequence in EDMD1 or EDMD2 fibroblasts, respectively, we observe a reduced expression of fibrogenic molecules. However, in patient myoblasts, neither fibrogenic proteins nor miRNA-21 were upregulated; instead, miRNA-21-5p was downregulated along with muscle-specific miRNA-133b and miRNA-206, which have a crucial role in muscle cell homeostasis. These observations suggest that the conversion of laminopathic fibroblasts into a profibrotic phenotype is a determinant of EDMD-associated muscle fibrosis, while miRNA-206-dependent defects of laminopathic myoblasts, including altered regulation of VEGF levels, contribute to muscle cell deterioration. Notably, our study provides a proof-of-principle for the application of gene correction to EDMD1 and EDMD2 and presents EDMD1 isogenic cells that exhibit an almost complete rescue of a disease-specific miRNA signature. These cells can be used as experimental models for studying muscular laminopathies.

Nesprins are a family of spectrin-repeat proteins located at the nuclear envelope which play an important role in nuclear morphology and mechano-transduction. Nesprin-1 and Nesprin-2, encoded by the synaptic nuclear envelope SYNE1 and SYNE2, are highly expressed in cardiac and skeletal muscle. Mutations in SYNE1 have been associated with the autosomal dominant Emery‐Dreifuss Muscular Dystrophy (EDMD) type 4, Congenital Muscular Dystrophy, and Arthrogryposis Multiplex Congenita while mutations in SYNE2 only with Emery‐Dreifuss muscular dystrophy type 5. In this study, we aimed at defining the clinical characteristics, histopathological features and molecular profile of 54 patients carrying single nucleotide variants in SYNE1 and SYNE2 genes. Multiple algorithms were used to predict the deleteriousness of the variants and only variants with Combined Annotation Dependent Depletion (CADD) scores ≥20 were selected. In our cohort 56% of patients were women; 60% of patients had late onset myopathy and 23% of patients presented with EDMD-like phenotype. In 80% of patients muscle biopsy showed myopathic signs, with dystrophic changes in the 28% of cases. The subcellular localization of Nesprin-1 and -2 and their co-localization with Emerin, an inner nuclear membrane protein, were evaluated by immunofluorescence in muscle tissue from 21 patients and neither reduced nuclear staining nor mislocalization of both nesprins were detected. Our data provide a further insight into the clinical phenotypes and muscle pathology associated with SYNE1 or SYNE2 mutations and suggest that immunohistochemistry does not represent a useful diagnostic tool.

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.

Cockayne syndrome (CS) and UV-sensitive syndrome (UVSS) are rare genetic disorders caused by mutation of the DNA repair and multifunctional CSA or CSB protein, but only CS patients display a progeroid and neurodegenerative phenotype, providing a unique conceptual and experimental paradigm. As DNA methylation (DNAm) remodelling is a major ageing marker, we performed genome-wide analysis of DNAm of fibroblasts from healthy, UVSS and CS individuals. Differential analysis highlighted a CS-specific epigenomic signature (progeroid-related; not present in UVSS) enriched in three categories: developmental transcription factors, ion/neurotransmitter membrane transporters and synaptic neuro-developmental genes. A large fraction of CS-specific DNAm changes were associated with expression changes in CS samples, including in previously reported post-mortem cerebella. The progeroid phenotype of CS was further supported by epigenomic hallmarks of ageing: the prediction of DNAm of repetitive elements suggested an hypomethylation of Alu sequences in CS, and the epigenetic clock returned a marked increase in CS biological age respect to healthy and UVSS cells. The epigenomic remodelling of accelerated ageing in CS displayed both commonalities and differences with other progeroid diseases and regular ageing. CS shared DNAm changes with normal ageing more than other progeroid diseases do, and included genes functionally validated for regular ageing. Collectively, our results support the existence of an epigenomic basis of accelerated ageing in CS and unveil new genes and pathways that are potentially associated with the progeroid/degenerative phenotype.

COL2A1 gene encodes the alpha-1 chain of type-II procollagen. Heterozygous pathogenic variants are associated with the broad clinical spectrum of genetic diseases known as type-II collagenopathies. We aimed to characterize the NM_001844.5:c.1330G>A;p.Gly444Ser variant detected in the COL2A1 gene through trio-based prenatal exome sequencing in a fetus presenting a severe skeletal phenotype at 31 Gestational Weeks and in his previously undisclosed mild-affected father. Functional studies on father's cutaneous fibroblasts, along with in silico protein modeling and in vitro chondrocytes differentiation, showed intracellular accumulation of collagen-II, its localization in external Golgi vesicles and nuclear morphological alterations. Extracellular matrix showed a disorganized fibronectin network. These results showed that p.Gly444Ser variant alters procollagen molecules processing and the assembly of mature type-II collagen fibrils, according to COL2A1-chain disorganization, displayed by protein modeling. Clinical assessment at 38 y.o., through a reverse-phenotyping approach, revealed limp gait, short and stocky appearance. X-Ray and MRI showed pelvis asymmetry with severe morpho-structural alterations of the femoral heads bilaterally, consistent with a mild form of type-II collagenopathy. This study shows how the fusion of genomics and clinical expertise can drive a diagnosis supported by cellular and bioinformatics studies to effectively establish variants pathogenicity.

Hutchinson–Gilford progeria syndrome (HGPS) is a rare genetic disease that causes premature aging symptoms, such as vascular diseases, lipodystrophy, loss of bone mineral density, and alopecia. HGPS is mostly linked to a heterozygous and de novo mutation in the LMNA gene (c.1824 C > T; p.G608G), resulting in the production of a truncated prelamin A protein called “progerin”. Progerin accumulation causes nuclear dysfunction, premature senescence, and apoptosis. Here, we examined the effects of baricitinib (Bar), an FDA-approved JAK/STAT inhibitor, and a combination of Bar and lonafarnib (FTI) treatment on adipogenesis using skin-derived precursors (SKPs). We analyzed the effect of these treatments on the differentiation potential of SKPs isolated from pre-established human primary fibroblast cultures. Compared to mock-treated HGPS SKPs, Bar and Bar + FTI treatments improved the differentiation of HGPS SKPs into adipocytes and lipid droplet formation. Similarly, Bar and Bar + FTI treatments improved the differentiation of SKPs derived from patients with two other lipodystrophic diseases: familial partial lipodystrophy type 2 (FPLD2) and mandibuloacral dysplasia type B (MADB). Overall, the results show that Bar treatment improves adipogenesis and lipid droplet formation in HGPS, FPLD2, and MADB, indicating that Bar + FTI treatment might further ameliorate HGPS pathologies compared to lonafarnib treatment alone.

Type-2 Familial Partial Lipodystrophy (FPLD2), a rare lipodystrophy caused by LMNA mutations, is characterized by a loss of subcutaneous fat from the trunk and limbs and excess accumulation of adipose tissue in the neck and face. Several studies have reported that the mineralocorticoid receptor (MR) plays an essential role in adipose tissue differentiation and functionality. We previously showed that brown preadipocytes isolated from a FPLD2 patient’s neck aberrantly differentiate towards the white lineage. As this condition may be related to MR activation, we suspected altered MR dynamics in FPLD2. Despite cytoplasmic MR localization in control brown adipocytes, retention of MR was observed in FPLD2 brown adipocyte nuclei. Moreover, overexpression of wild-type or mutated prelamin A caused GFP-MR recruitment to the nuclear envelope in HEK293 cells, while drug-induced prelamin A co-localized with endogenous MR in human preadipocytes. Based on in silico analysis and in situ protein ligation assays, we could suggest an interaction between prelamin A and MR, which appears to be inhibited by mineralocorticoid receptor antagonism. Importantly, the MR antagonist spironolactone redirected FPLD2 preadipocyte differentiation towards the brown lineage, avoiding the formation of enlarged and dysmorphic lipid droplets. Finally, beneficial effects on brown adipose tissue activity were observed in an FPLD2 patient undergoing spironolactone treatment. These findings identify MR as a new lamin A interactor and a new player in lamin A-linked lipodystrophies.

Little is known about how the observed fat-specific pattern of 3D-spatial genome organisation is established. Here we report that adipocyte-specific knockout of the gene encoding nuclear envelope transmembrane protein Tmem120a disrupts fat genome organisation, thus causing a lipodystrophy syndrome. Tmem120a deficiency broadly suppresses lipid metabolism pathway gene expression and induces myogenic gene expression by repositioning genes, enhancers and miRNA-encoding loci between the nuclear periphery and interior. Tmem120a −/− mice, particularly females, exhibit a lipodystrophy syndrome similar to human familial partial lipodystrophy FPLD2, with profound insulin resistance and metabolic defects that manifest upon exposure to an obesogenic diet. Interestingly, similar genome organisation defects occurred in cells from FPLD2 patients that harbour nuclear envelope protein encoding LMNA mutations. Our data indicate TMEM120A genome organisation functions affect many adipose functions and its loss may yield adiposity spectrum disorders, including a miRNA-based mechanism that could explain muscle hypertrophy in human lipodystrophy. Little is known how spatial genome organization is directed in fat; however, key proadipogenic genes reposition from the nuclear envelope (NE) to the interior during adipogenesis. Here the authors show that deletion of NE protein Tmem120a in adipocytes disrupts fat genome organization, which results in suppression of lipid metabolism pathways and induces myogenic gene expression.

Lamin A, a main constituent of the nuclear lamina, is involved in mechanosignaling and cell migration through dynamic interactions with the LINC complex, formed by the nuclear envelope proteins SUN1, SUN2 and the nesprins. Here, we investigated lamin A role in Ewing Sarcoma (EWS), an aggressive bone tumor affecting children and young adults. In patients affected by EWS, we found a significant inverse correlation between LMNA gene expression and tumor aggressiveness. Accordingly, in experimental in vitro models, low lamin A expression correlated with enhanced cell migration and invasiveness and, in vivo, with an increased metastatic load. At the molecular level, this condition was linked to altered expression and anchorage of nuclear envelope proteins and increased nuclear retention of YAP/TAZ, a mechanosignaling effector. Conversely, overexpression of lamin A rescued LINC complex organization, thus reducing YAP/TAZ nuclear recruitment and preventing cell invasiveness. These effects were also obtained through modulation of lamin A maturation by a statin-based pharmacological treatment that further elicited a more differentiated phenotype in EWS cells. These results demonstrate that drugs inducing nuclear envelope remodeling could be exploited to improve therapeutic strategies for EWS.

Cardiolaminopathies are a heterogeneous group of disorders which are due to mutations in the genes encoding for nuclear lamins or their binding proteins. The whole spectrum of cardiac manifestations encompasses atrial arrhythmias, conduction disturbances, progressive systolic dysfunction, and malignant ventricular arrhythmias. Despite the prognostic significance of cardiac involvement in this setting, the current recommendations lack strong evidence. The aim of our work was to systematically review the current data on the main cardiovascular outcomes in cardiolaminopathies. We searched PubMed/Embase for studies focusing on cardiovascular outcomes in LMNA mutation carriers (atrial arrhythmias, ventricular arrhythmias, sudden cardiac death, conduction disturbances, thromboembolic events, systolic dysfunction, heart transplantation, and all-cause and cardiovascular mortality). In total, 11 studies were included (1070 patients, mean age between 26–45 years, with follow-up periods ranging from 2.5 years up to 45 ± 12). When available, data on the EMD-mutated population were separately reported (40 patients). The incidence rates (IR) were individually assessed for the outcomes of interest. The IR for atrial fibrillation/atrial flutter/atrial tachycardia ranged between 6.1 and 13.9 events/100 pts–year. The IR of atrial standstill ranged between 0 and 2 events/100 pts-year. The IR for malignant ventricular arrhythmias reached 10.2 events/100 pts–year and 15.6 events/100 pts–year for appropriate implantable cardioverter–defibrillator (ICD) interventions. The IR for advanced conduction disturbances ranged between 3.2 and 7.7 events/100 pts–year. The IR of thromboembolic events reached up to 8.9 events/100 pts–year. Our results strengthen the need for periodic cardiological evaluation focusing on the early recognition of atrial arrhythmias, and possibly for the choice of preventive strategies for thromboembolic events. The frequent need for cardiac pacing due to advanced conduction disturbances should be counterbalanced with the high risk of malignant ventricular arrhythmias that would justify ICD over pacemaker implantation.

LMNA-related congenital muscular dystrophy (L-CMD) and LMNA-linked Emery-Dreifuss muscular dystrophy (EDMD2) with early onset (<5 years) may be considered a continuum phenotype. There is no cure for patients with these neuromuscular diseases. Literature data and ongoing clinical approaches suggest the use of steroids. Starting from the collaborative approach and the multidisciplinary effort of the Italian network for laminopathies, we are planning an open-label prospective cohort pilot study aimed to: 1) evaluate the effect of the treatment with deflazacort in a cohort of 20 L-CMD or EDMD2 patients with infantile onset, aged 3-30 years; 2) analyze the secretome profile at basal condition and during steroid treatment, to evaluate variations and establish a correlation between steroid treatment and clinical outcome; 3) validate selected cytokines as biomarkers for L-CMD and EDMD2. Study protocol: Patients will be monitored for a period of six months. Then, they will start therapy with Deflazacort for 12 months. After 12 months, the treatment will be stopped and the patients will continue to be clinically followed every 3 months until the end of the study. Overall, we expect to evaluate whether a 12-month-treatment with deflazacort is effective in improving clinical outcome measures in L-CMD patients. We also expect to identify a panel of cytokines altered in L-CMD that can be considered as biomarkers of disease. LMNA-related congenital muscular dystrophy (L-CMD) and LMNA-linked Emery-Dreifuss muscular dystrophy (EDMD2) with early onset (<5 years) may be considered a continuum phenotype. There is no cure for patients with these neuromuscular diseases. Literature data and ongoing clinical approaches suggest the use of steroids. Starting from the collaborative approach and the multidisciplinary effort of the Italian network for laminopathies, we are planning an open-label prospective cohort pilot study aimed to: 1) evaluate the effect of the treatment with deflazacort in a cohort of 20 L-CMD or EDMD2 patients with infantile onset, aged 3-30 years; 2) analyze the secretome profile at basal condition and during steroid treatment, to evaluate variations and establish a correlation between steroid treatment and clinical outcome; 3) validate selected cytokines as biomarkers for L-CMD and EDMD2. Study protocol: Patients will be monitored for a period of six months. Then, they will start therapy with Deflazacort for 12 months. After 12 months, the treatment will be stopped and the patients will continue to be clinically followed every 3 months until the end of the study. Overall, we expect to evaluate whether a 12-month-treatment with deflazacort is effective in improving clinical outcome measures in L-CMD patients. We also expect to identify a panel of cytokines altered in L-CMD that can be considered as biomarkers of disease.