Mesenchymal stem cells (MSCs) of placental origin hold great promise in tissue engineering and regenerative medicine for diseases affecting cartilage and bone. However, their utility has been limited by their tendency to undergo premature senescence and phenotypic drift into adipocytes. This study aimed to explore the potential involvement of a specific subset of aging and antiaging genes by measuring their expression prior to and following in vitro-induced differentiation of placental MSCs into chondrocytes and osteoblasts as opposed to adipocytes. The targeted genes of interest included the various LMNA/C transcript variants (lamin A, lamin C, and lamin A∆10), sirtuin 7 (SIRT7), and SM22α, along with the classic aging markers plasminogen activator inhibitor 1 (PAI-1), p53, and p16INK4a. MSCs were isolated from the decidua basalis of human term placentas, expanded, and then analyzed for phenotypic properties by flow cytometry and evaluated for colony-forming efficiency. The cells were then induced to differentiate in vitro into chondrocytes, osteocytes, and adipocytes following established protocols. The mRNA expression of the targeted genes was measured by RT-qPCR in the undifferentiated cells and those fully differentiated into the three cellular lineages. Compared to undifferentiated cells, the differentiated chondrocytes demonstrated decreased expression of SIRT7, along with decreased PAI-1, lamin A, and SM22α expression, but the expression of p16INK4a and p53 increased, suggesting their tendency to undergo premature senescence. Interestingly, the cells maintained the expression of lamin C, which indicates that it is the primary lamin variant influencing the mechanoelastic properties of the differentiated cells. Notably, the expression of all targeted genes did not differ from the undifferentiated cells following osteogenic differentiation. On the other hand, the differentiation of the cells into adipocytes was associated with decreased expression of lamin A and PAI-1. The distinct patterns of expression of aging and antiaging genes following in vitro-induced differentiation of MSCs into chondrocytes, osteocytes, and adipocytes potentially reflect specific roles for these genes during and following differentiation in the fully functional cells. Understanding these roles and the network of signaling molecules involved can open opportunities to improve the handling and utility of MSCs as cellular precursors for the treatment of cartilage and bone diseases.

Progerin, the protein that causes Hutchinson-Gilford progeria syndrome, triggers nuclear membrane (NM) ruptures and blebs, but the mechanisms are unclear. We suspected that the expression of progerin changes the overall structure of the nuclear lamina. High-resolution microscopy of smooth muscle cells (SMCs) revealed that lamin A and lamin B1 form independent meshworks with uniformly spaced openings (~0.085 µm2). The expression of progerin in SMCs resulted in the formation of an irregular meshwork with clusters of large openings (up to 1.4 µm2). The expression of progerin acted in a dominant-negative fashion to disrupt the morphology of the endogenous lamin B1 meshwork, triggering irregularities and large openings that closely resembled the irregularities and openings in the progerin meshwork. These abnormal meshworks were strongly associated with NM ruptures and blebs. Of note, the progerin meshwork was markedly abnormal in nuclear blebs that were deficient in lamin B1 (~50% of all blebs). That observation suggested that higher levels of lamin B1 expression might normalize the progerin meshwork and prevent NM ruptures and blebs. Indeed, increased lamin B1 expression reversed the morphological abnormalities in the progerin meshwork and markedly reduced the frequency of NM ruptures and blebs. Thus, progerin expression disrupts the overall structure of the nuclear lamina, but that effect-along with NM ruptures and blebs-can be abrogated by increased lamin B1 expression.

Pathogenic variants in LMNA have been associated with a wide spectrum of muscular conditions: the laminopathies. LMNA-related congenital muscular dystrophy is a laminopathy characterised by the early onset of symptoms and often leads to a fatal outcome at young ages. Children face a heightened risk of malignant arrhythmias. No established paediatric protocols for managing this condition are available. We review published cases and provide insights into disease progression in two twin sisters with LMNA-related muscular dystrophy. Our objective is to propose a cardiac surveillance and management plan tailored specifically for paediatric patients. We present a family of five members, including two twin sisters with LMNA-related muscular dystrophy. A comprehensive neuromuscular and cardiac work-up was performed in all family members. Genetic analysis using massive sequencing technology was performed in both twins. Clinical assessment showed that only the twins showed diagnoses of LMNA-related muscular dystrophy. Follow-up showed an early onset of symptoms and life-threatening arrhythmias, with differing disease progressions despite both twins passing away. Genetic analysis identified a de novo rare missense deleterious variant in the LMNA gene. Other additional rare variants were identified in genes associated with myasthenic syndrome. Early-onset neuromuscular symptoms could be related to a prognosis of worse life-threatening arrhythmias in LMNA related muscular dystrophy. Being a carrier of other rare variants may be a modifying factor in the progression of the phenotype, although further studies are needed. There is a pressing need for specific cardiac recommendations tailored to the paediatric population to mitigate the risk of malignant arrhythmias.

UNASSIGNED: There is a lack of information on the clinical and molecular presentation of familial partial lipodystrophy (FPLD), a rare genetic disorder characterized by partial subcutaneous fat loss.
UNASSIGNED: This study aimed to provide a comprehensive assessment of the clinical, metabolic, and genetic features of FPLD in the Brazilian population.
UNASSIGNED: In a multicenter cross-sectional investigation we evaluated patients with FPLD across five Brazilian reference centers for lipodystrophies. Diagnosis of FPLD was made by clinical evaluation and genetic confirmation. Data on genetic, clinical, and metabolic characteristics were captured. Statistical analysis involved the utilization of the Kruskal-Wallis test to identify differences.
UNASSIGNED: The study included 106 patients with genetic confirmation of FPLD. The mean age was 44 ± 15 years, and they were predominantly female (78.3%). LMNA pathogenic variants were identified in 85.8% of patients, PPARG in 10.4%, PLIN1 in 2.8%, and MFN2 in 0.9%. Diabetes mellitus (DM) was highly prevalent (57.5%), affecting 54 females (50.9%). Median triglycerides levels were 199 mg/dL (54-2724 mg/dL), severe hypertriglyceridemia (≥ 500 mg/dL) was found in 34.9% and pancreatitis in 8.5%. Metabolic-associated fatty liver disease (MAFLD) was observed in 56.6%, and cardiovascular disease in 10.4%. The overall mortality rate was 3.8%, due to cardiovascular events.
UNASSIGNED: This study presents an extensive cohort of Brazilian patients with FPLD, predominantly DM with several multisystem complications. A comprehensive characterization of lipodystrophy syndromes is crucial for effective patient management and care.

暂无摘要。

Lamin A/C gene (LMNA) mutations contribute to severe striated muscle laminopathies, affecting cardiac and skeletal muscles, with limited treatment options. In this study, we delve into the investigations of five distinct LMNA mutations, including three novel variants and two pathogenic variants identified in patients with muscular laminopathy. Our approach employs zebrafish models to comprehensively study these variants. Transgenic zebrafish expressing wild-type LMNA and each mutation undergo extensive morphological profiling, swimming behavior assessments, muscle endurance evaluations, heartbeat measurement, and histopathological analysis of skeletal muscles. Additionally, these models serve as platform for focused drug screening. We explore the transcriptomic landscape through qPCR and RNAseq to unveil altered gene expression profiles in muscle tissues. Larvae of LMNA(L35P), LMNA(E358K), and LMNA(R453W) transgenic fish exhibit reduced swim speed compared to LMNA(WT) measured by DanioVision. All LMNA transgenic adult fish exhibit reduced swim speed compared to LMNA(WT) in T-maze. Moreover, all LMNA transgenic adult fish, except LMNA(E358K), display weaker muscle endurance than LMNA(WT) measured by swimming tunnel. Histochemical staining reveals decreased fiber size in all LMNA mutations transgenic fish, excluding LMNA(WT) fish. Interestingly, LMNA(A539V) and LMNA(E358K) exhibited elevated heartbeats. We recognize potential limitations with transgene overexpression and conducted association calculations to explore its effects on zebrafish phenotypes. Our results suggest lamin A/C overexpression may not directly impact mutant phenotypes, such as impaired swim speed, increased heart rates, or decreased muscle fiber diameter. Utilizing LMNA zebrafish models for drug screening, we identify L-carnitine treatment rescuing muscle endurance in LMNA(L35P) and creatine treatment reversing muscle endurance in LMNA(R453W) zebrafish models. Creatine activates AMPK and mTOR pathways, improving muscle endurance and swim speed in LMNA(R453W) fish. Transcriptomic profiling reveals upstream regulators and affected genes contributing to motor dysfunction, cardiac anomalies, and ion flux dysregulation in LMNA mutant transgenic fish. These findings faithfully mimic clinical manifestations of muscular laminopathies, including dysmorphism, early mortality, decreased fiber size, and muscle dysfunction in zebrafish. Furthermore, our drug screening results suggest L-carnitine and creatine treatments as potential rescuers of muscle endurance in LMNA(L35P) and LMNA(R453W) zebrafish models. Our study offers valuable insights into the future development of potential treatments for LMNA-related muscular laminopathy.

OBJECTIVE: To report the case of a girl presenting a severe phenotype of mandibuloacral dysplasia type A (MADA) characterized by prominent osteolytic changes and ectodermal defects, associated with a rare homozygous LMNA missense mutation (c.1579C>T).
METHODS: A 6-year-old girl was evaluated during hospitalization exhibiting the following dysmorphic signs: subtotal alopecia, dysmorphic facies with prominent eyes, marked micrognathia and retrognathia, small beaked nose, teeth crowding and thin lips, generalized lipodystrophy, narrow and sloping shoulders, generalized joint stiffness and bone reabsorption in the terminal phalanges. In dermatological examination, atrophic skin, loss of cutaneous elasticity, hyperkeratosis, dermal calcinosis, and hyperpigmented and hypochromic patches were observed. Radiology exams performed showed bilateral absence of the mandibular condyles, clavicle resorption with local amorphous bone mass confluence with the scapulae, shoulder joints with subluxation and severe bone dysplasia, hip dysplasia, osteopenia and subcutaneous calcifications.
CONCLUSIONS: MADA is a rare autosomal recessive disease caused by mutations in LMNA gene. It is characterized by craniofacial deformities, skeletal anomalies, skin alterations, lipodystrophy in certain regions of the body and premature ageing. Typical MADA is caused by the p.R527H mutation in the LMNA gene. However, molecular analysis performed from oral epithelial cells obtained from the patient showed the rare mutation c.1579C>T, p. R527C in the exon 9 of LMNA. This is the sixth family identified with this mutation described in the literature.

Lipodystrophies are characterized by complete or selective loss of adipose tissue and can be acquired or inherited. Familial partial lipodystrophy (FPLD) is a hereditary lipodystrophy commonly caused by mutations in the LMNA gene. Herein, we report two cases of FPLD associated with podocytopathies. Patient 1 was diagnosed with FPLD associated with the heterozygous p.Arg482Trp variant in LMNA and had normal glucose tolerance and hyperinsulinemia. During follow-up, she developed nephroticrange proteinuria. Renal biopsy was consistent with minimal change disease. Patient 2 was diagnosed with FPLD associated with a de novo heterozygous p.Arg349Trp variant in LMNA. Microalbuminuria progressed to macroalbuminuria within 6 years and tonephrotic range proteinuria in the last year. He remained without diabetes and with hyperinsulinemia. Renal biopsy revealed focal segmental glomerulosclerosis not otherwise specified. This report provides further evidence of variable features of lipodystrophy associated with LMNA variants and the importance of long-term follow-up with evaluation of kidney dysfunction.

Mutations in the LMNA gene-encoding A-type lamins can cause Limb-Girdle muscular dystrophy Type 1B (LGMD1B). This disease presents with weakness and wasting of the proximal skeletal muscles and has a variable age of onset and disease severity. This variability has been attributed to genetic background differences among individuals; however, such variants have not been well characterized. To identify such variants, we investigated a multigeneration family in which affected individuals are diagnosed with LGMD1B. The primary genetic cause of LGMD1B in this family is a dominant mutation that activates a cryptic splice site, leading to a five-nucleotide deletion in the mature mRNA. This results in a frame shift and a premature stop in translation. Skeletal muscle biopsies from the family members showed dystrophic features of variable severity, with the muscle fibers of some family members possessing cores, regions of sarcomeric disruption, and a paucity of mitochondria, not commonly associated with LGMD1B. Using whole genome sequencing (WGS), we identified 21 DNA sequence variants that segregate with the family members possessing more profound dystrophic features and muscle cores. These include a relatively common variant in coiled-coil domain containing protein 78 (CCDC78). This variant was given priority because another mutation in CCDC78 causes autosomal dominant centronuclear myopathy-4, which causes cores in addition to centrally positioned nuclei. Therefore, we analyzed muscle biopsies from family members and discovered that those with both the LMNA mutation and the CCDC78 variant contain muscle cores that accumulated both CCDC78 and RyR1. Muscle cores containing mislocalized CCDC78 and RyR1 were absent in the less profoundly affected family members possessing only the LMNA mutation. Taken together, our findings suggest that a relatively common variant in CCDC78 can impart profound muscle pathology in combination with a LMNA mutation and accounts for variability in skeletal muscle disease phenotypes.

Abnormal nuclear enlargement is a diagnostic and physical hallmark of malignant tumors. Large nuclei are positively associated with an increased risk of developing metastasis; however, a large nucleus is inevitably more resistant to cell migration due to its size. The present study demonstrated that the nuclear size of primary colorectal cancer (CRC) cells at an advanced stage was larger than cells at an early stage. In addition, the nuclei of CRC liver metastases were larger than those of the corresponding primary CRC tissues. CRC cells were sorted into large-nucleated cells (LNCs) and small-nucleated cells (SNCs). Purified LNCs exhibited greater constricted migratory and metastatic capacity than SNCs in vitro and in vivo. Mechanistically, ErbB4 was highly expressed in LNCs, which phosphorylated lamin A/C at serine 22 via the ErbB4-Akt1 signaling pathway. Furthermore, the level of phosphorylated lamin A/C was a negative determinant of nuclear stiffness. Taken together, CRC LNCs possessed greater constricted migratory and metastatic potential than SNCs due to ErbB4-Akt1-mediated lamin A/C phosphorylation and nuclear softening. These results may provide a potential treatment strategy for tumor metastasis by targeting nuclear stiffness in patients with cancer, particularly CRC.