BACKGROUND: Muscular A-type lamin-interacting protein (MLIP) has a regulatory role in myoblast differentiation and organization of myonuclear positioning in skeletal muscle. It is ubiquitously expressed but abundantly in cardiac, skeletal, and smooth muscles. Recently, two studies confirmed the causation of biallelic pathogenic variants in the MLIP gene of a novel myopathy phenotype.
OBJECTIVE: Description of the phenotypic spectrum and features of MLIP-related myopathy.
METHODS: report a patient with biallelic variants in MLIP gene with the clinical features, and histomorphological findings of MLIP-related myopathy and provide a literature review of the previously reported 12 patients.
RESULTS: MLIP-related myopathy is characterized by episodes of rhabdomyolysis, myalgia triggered by mild to moderate exercise, mild muscle weakness, and sometimes cardiac involvement characterized by cardiomyopathy and cardiac rhythm abnormalities.
CONCLUSIONS: This report reviews and extends the clinical features of a novel myopathy caused by biallelic pathogenic variants in the MLIP gene.

In the last decades, atomic force microscopy (AFM) underwent a rapid and stunning development, especially for studying mechanical properties of biological samples. The numerous discoveries relying to this approach, have increased the credit of AFM as a versatile tool, and potentially eligible as a diagnostic equipment. Meanwhile, it has become strikingly evident that lamins are involved on the onset and development of certain diseases, including cancer, Hutchinson-Gilford progeria syndrome, cardiovascular pathologies, and muscular dystrophy. A new category of pathologies has been defined, the laminopathies, which are caused by mutations in the gene encoding for A-type lamins. As the majority of medical issues, lamins, and all their related aspects can be considered as a quite complex problem. Indeed, there are many facets to explore, and this definitely requires a multidisciplinary approach. One of the most intriguing aspects concerning lamins is their remarkable contribute to cells mechanics. Over the years, this has led to the speculation of the so-called \"structural hypothesis\", which attempts to elucidate the etiology and some features of the laminopathies. Among the various techniques tried to figure out the role of lamins in the cells mechanics, the AFM has been already successfully applied, proving its versatility. Therefore, the present work aims both to highlight the qualities of AFM and to review the most relevant knowledge about lamins, in order to promote the study of the latter, taking advantage from the former. Microsc. Res. Tech. 80:97-108, 2017. © 2016 Wiley Periodicals, Inc.

Our life span is genetically programmed and it is possible that a defect in produced proteins encoded by the longevity gene is a cause of aging. Progeria which is a rare, fatal genetic condition which affects between one in four million and one in eight million children of both sexes equally and characterized by premature and accelerated aging. The appearance and physiology of these children resembles to elderly people but they typically have life span to their mid teens. It is also known as the Hutchinson-Gilford syndrome, which was initially reported by Johnathan Hutchinson in 1886 and further described by Hastings Gilford in 1904. It is an autosomal recessive disorder, which means an individual has inherited a mutated gene from both parents. It is added to the expanding catalogue of laminopathies, diseases caused by mutations affecting nuclear lamina proteins known as lamin A (LMNA). In oral manifestation primary finding is micrognathia with delayed tooth eruption and incomplete formation of root of permanent tooth. Presently there are no known cures for this abnormality.

Nuclear margin irregularity is an important diagnostic feature of malignant cells. The exact cause of nuclear margin irregularity is not fully understood. The distortion of the nuclear envelope is probably the major factor in nuclear margin irregularity. Multiple proteins on the nuclear envelope, particularly nuclear lamin, are responsible for the distortion of the nuclear envelope. The extracellular matrix may also indirectly affect the nuclear position and shape by the closely connected network of actin-nespirin-SUN-lamin links. The alteration of nuclear matrix protein and RET-oncogene expression may play a role in nuclear envelope distortion and in margin irregularity. In this review, the probable causes and impact of nuclear margin irregularities are discussed.

Restrictive dermopathy (RD) is a rare, severe, lethal genodermatosis in which tautness of the skin causes fetal akinesia or hypokinesia deformation sequence. To date, about 60 cases of RD were described. The signs of the disease are very characteristic and include intrauterine growth retardation, thin, tightly adherent translucent skin, superficial vessels, typical facial dysmorphism as well as generalized joint contractures. The syndrome is caused in most cases by ZMPSTE24 autosomal recessive mutations, or, less frequently, by LMNA autosomal dominant mutations. We report on two brothers affected with RD, who died in the neonatal period. Molecular analyses were performed in the second child, for whom biological material was available, and both parents. Compound heterozygous frameshifting mutations were identified in exon 1 (c.50delA) and exon 5 (c.584_585delAT) of the ZMPSTE24 gene. The autosomal recessive inheritance was confirmed by the parents\' genomic analysis. Besides, a review of the mutations causing RD is made.

The nuclear lamins are members of the intermediate filament (IF) family of proteins. The lamins have an essential role in maintaining nuclear integrity, as do the other IF family members in the cytoplasm. Also like cytoplasmic IFs, the organization of lamins is dynamic. The lamins are found not only at the nuclear periphery but also in the interior of the nucleus, as distinct nucleoplasmic foci and possibly as a network throughout the nucleus. Nuclear processes such as DNA replication may be organized around these structures. In this review, we discuss changes in the structure and organization of the nuclear lamins during the cell cycle and during cell differentiation. These changes are correlated with changes in nuclear structure and function. For example, the interactions of lamins with chromatin and nuclear envelope components occur very early during nuclear assembly following mitosis. During S-phase, the lamins colocalize with markers of DNA replication, and proper lamin organization must be maintained for replication to proceed. When cells differentiate, the expression pattern of lamin isotypes changes. In addition, changes in lamin organization and expression patterns accompany the nuclear alterations observed in transformed cells. These lamin structures may modulate nuclear function in each of these processes.

The nuclear lamina is located between the inner nuclear membrane and the peripheral chromatin. It is composed of both peripheral and integral membrane proteins, including lamins and lamina-associated proteins. Lamins can interact with one another, with lamina-associated proteins, with nuclear scaffold proteins, and with chromatin. Likewise, most of the lamina-associated proteins are likely to interact directly with chromatin. The nuclear lamina is required for proper cell cycle regulation, chromatin organization, DNA replication, cell differentiation, and apoptosis. Mutations in proteins of the nuclear lamina can disrupt these activities and cause genetic diseases. The structure and assembly of the nuclear lamina proteins and their roles in chromatin organization and cell cycle regulation were recently reviewed. In this review, we discuss the roles of the nuclear lamina in DNA replication and apoptosis and analyze how mutations in nuclear lamina proteins might cause genetic diseases.

This review presents the current knowledge of the basic biology of intermediate filaments, including their phylogenetic distribution and their distribution within mammalian cells. The current understanding of their structure, recently described using recombinant DNA, peptide sequencing, and immunologic methods, is discussed in terms of a revised chemical classification that not only includes the acidic and neutral basic keratins, vimentin, glial fibrillary protein, desmin, and neurofilament, but also includes the more recently related nuclear lamins. This new structural knowledge allows a more rational approach to the diagnostic use and development of polyclonal and monoclonal anti-intermediate filament antibodies. Many of the problems encountered with fixation, cross-reactivity, and epitope masking can be related to these structural concepts.