Defects In Structural Proteins Research Articles

Impact of low-dose calcipotriol ointment on wound healing, pruritus and pain in patients with dystrophic epidermolysis bullosa: A randomized, double-blind, placebo-controlled trial

BackgroundWound management is a critical factor when treating patients with the inherited skin fragility disease dystrophic epidermolysis bullosa (DEB). Due to genetic defects in structural proteins, skin and mucous epithelia are prone to blistering and chronic wounding upon minor trauma. Furthermore, these wounds are commonly associated with excessive pruritus and predispose to the development of life-threatening squamous cell carcinomas, underscoring the unmet need for new therapeutic options to improve wound healing in this patient cohort. Vitamin D3 is acknowledged to play an important role in wound healing by modulating different cellular processes that impact epidermal homeostasis and immune responses. In this study, we evaluate the safety and efficacy of low-dose calcipotriol, a vitamin D3 analogue, in promoting wound healing and reducing itch and pain in patients with DEB.MethodsEligible DEB patients, aged ≥ 6 years and with a known mutation in the COL7A1 gene, were recruited to a placebo-controlled, randomized, double blind, cross-over phase II monocentric clinical trial. Patients were required to have at least two wounds with a minimum size of 6 cm2 per wound. The primary objective was to evaluate efficacy of daily topical application of a 0.05 µg/g calcipotriol ointment in reducing wound size within a 4-week treatment regimen. Secondary objectives were to assess safety, as well as the impact of treatment on pruritus, pain, and bacterial wound colonization in these patients.ResultsSix patients completed the clinical trial and were included into the final analysis. Topical low-dose calcipotriol treatment led to a significant reduction in wound area at day 14 compared to placebo (88.4% vs. 65.5%, P < 0.05). Patients also reported a significant reduction of pruritus with calcipotriol ointment compared to placebo over the entire course of the treatment as shown by itch scores of 3.16 vs 4.83 (P < 0.05) and 1.83 vs 5.52 (P < 0.0001) at days 14 and 28, respectively. Treatment with low-dose calcipotriol did not affect serum calcium levels and improved the species richness of the wound microbiome, albeit with no statistical significance.ConclusionsOur results show that topical treatment with low-dose calcipotriol can accelerate wound closure and significantly reduces itch, and can be considered a safe and readily-available option to improve local wound care in DEB patients.TrialRegistration EudraCT: 2016–001,967-35. Registered 28 June 2016, https://www.clinicaltrialsregister.eu/ctr-search/trial/2016-001967-35/AT

Congenital nephrotic syndrome associated with 22q11.2 duplication syndrome in a Chinese family and functional analysis of the intronic NPHS1 c. 3286 + 5G > A mutation

BackgroundCongenital nephrotic syndrome (CNS), which is defined as heavy proteinuria, hypoalbuminemia, hyperlipidemia and edema, is most caused by monogenic defects in structural proteins of the glomerular filtration barrier in the kidneys. 22q11.2 duplication syndrome was a chromosomal disease with variable clinical featuresranging from normal to mental retardation and with congenital defects. Co-occurrence of two genetic disorders in a single patient is rare.Case presentationThe proband was born at 36 weeks of gestational age spontaneously and weighed 2350 g at birth. Six days after birth, the proband was admitted to our hospital due to fever of 38.5 °C lasting for 6 h. Physical examination at admission time showed dysmorphic features of hypertelorism, palpebral edema, broad nose bridge, upturned nose, dysmorphic auricle, long philtrum, and a thin upper lip. Additionally, we found left wrist drop and bilateral strephexopodia, bilateral knee joint flexion contracture in this patient. A series of indicators were detected and showed abnormalities. Albumin was used to remit the hypoproteinemia and edema. However, the parents refused to accept further therapy and the boy died at age 3 months due to cachexy. To confirm the pathogenesis, genetic analysis were performed and revealed two mutations of NPHS1 gene: Exon18: c.2386G > C; p. (Gly796Arg) inherited from mother, and intron24: c.3286 + 5G > A; p.? inherited from father. And he also had a 22q11.2 duplication which was inherited from his mild affected mother. The pathogenesis of the intronic mutation has been further identified that it can defect alternative splicing of NPHS1.ConclusionsWe present a patient who was caught in congenital nephrotic syndrome and 22q11.2 duplication syndrome simultaneously, emphasizing the importance of new sequencing technology on diagnosis of different genetic disorders.

Mechanical Properties of Tandem-Repeat Proteins Are Governed by Network Defects.

Topological defects in highly repetitive structural proteins strongly affect their mechanical properties. However, there are no universal rules for structure-property prediction in structural proteins due to high diversity in their repetitive modules. Here, we studied the mechanical properties of tandem-repeat proteins inspired by squid ring teeth proteins using rheology and tensile experiments as well as spectroscopic and X-ray techniques. We also developed a network model based on entropic elasticity to predict structure-property relationships for these proteins. We demonstrated that shear modulus, elastic modulus, and toughness scale inversely with the number of repeats in these proteins. Through optimization of structural repeats, we obtained highly efficient protein network topologies with 42 MJ/m3 ultimate toughness that are capable of withstanding deformations up to 350% when hydrated. Investigation of topological network defects in structural proteins will improve the prediction of mechanical properties for designing novel protein-based materials.

The etiology of congenital nephrotic syndrome: current status and challenges.

Congenital nephrotic syndrome (CNS), defined as heavy proteinuria, hypoalbuminemia, hyperlipidemia and edema presenting in the first 0-3 months of life, may be caused by congenital syphilis, toxoplasmosis, or congenital viral infections (such as cytomegalovirus). However, the majority of CNS cases are caused by monogenic defects of structural proteins that form the glomerular filtration barrier in the kidneys. Since 1998, an increasing number of genetic defects have been identified for their involvements in the pathogenesis of CNS, including NPHS1, NPHS2, WT1, PLCE1, and LAMB2. We searched databases such as PubMed, Elsevier and Wanfang with the following key words: congenital nephrotic syndrome, proteinuria, infants, neonate, congenital infection, mechanism and treatment; and we selected those publications written in English that we judged to be relevant to the topic of this review. Based on the data present in the literature, we reviewed the following topics: 1) Infection associated CNS including congenital syphilis, congenital toxoplasmosis, and congenital cytomegalovirus infection; 2) genetic CNS including mutation of NPHS1 (Nephrin), NPHS2 (Podocin), WT1, LAMB2 (Laminin-β2), PLCE1 (NPHS3); 3) Other forms of CNS including maternal systemic lupus erythematosus, mercury poisoning, renal vein thrombosis, neonatal alloimmunization against neutral endopeptidase. At present, the main challenge in CNS is to identify the cause of disease for individual patients. To make a definitive diagnosis, with the exclusion of infection-related CNS and maternal-associated disorders, pathology, family history, inheritance mode, and other accompanying congenital malformations are sometimes, but not always, useful indicators for diagnosing genetic CNS. Next-generation sequencing would be a more effective method for diagnosing genetic CNS in some patients, however, there are still some challenges with next-generation sequencing that need to be resolved in the future.

A decade in search of myopia genes

Nearly half of visual impairment in the world is caused by uncorrected refractive errors, and myopia constitutes a significant proportion of this problem. Moreover, the prevalence of myopia is increasing, especially in Asian countries. Linkage studies have identified at least 18 possible loci (MYP) in 15 different chromosomes associated with myopia, although some of these remain to be confirmed. However, when studies have been carried out to identify specific candidate genes, it is apparent that these genes are often not part of MYP loci. In studying the expression of specific genes that might be responsible for myopia, we are learning that the involvement of various small leucine-rich repeat proteoglycans and growth factors is not a simple one. The emerging picture is one of complex interaction, in which mutations in several genes likely act in concert. The majority of myopia cases are not likely caused by defects in structural proteins, but in defects involving the control of structural proteins. The future of genetic research in this area will likely rely increasingly on microchip array technology.

Symposium S02: Muscle Disorders with Genetic Defects of Structural Proteins

Brain PathologyVolume 10, Issue 4 p. 498-499 Free to Read Symposium S02: Muscle Disorders with Genetic Defects of Structural Proteins First published: 05 April 2006 https://doi.org/10.1111/j.1750-3639.2000.tb00284.xAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat No abstract is available for this article. Volume10, Issue4October 2000Pages 498-499 RelatedInformation

Genes Help Unravel Marfan Pathology, Point Way to Potential New Therapies

MODERN GENETIC TECHNIQUES are providing new insights into the pathogenesis of Marfan syndrome, a genetic disorder that can cause skeletal malformations and abnormalities of the heart and other organs. In the process, these insights are challenging long-held beliefs about the disease and related disorders and raising hope for better treatments. Such hope counters the pessimism that accompanied the 1991 discovery that Marfan syndrome is caused by mutations in the gene that encodes fibrillin-1, a component of the extracellular matrix (Dietz et al. Nature. 1991; 352:337-339). After all, defects in structural proteins throughout the body would be nearly impossible to correct. But more recent discoveries suggest that fibrillin-1 regulates transforming growth factor(TGF) and show that excessive activity of this protein appears to play an integral role in the pathogenesis of Marfan syndrome and some related disorders. The finding regarding of TGF’s role in the disease also points to potential targets for future therapies. Peter H. Byers, MD, medical geneticist and professor in the departments of pathology and medicine at the University of Washington, in Seattle, said the discoveries mark a dramatic shift in the understanding of Marfan syndrome and bolster a long-standing theory that extracellular matrix proteins play a regulatory role as well as a structural one. “It has opened up the door to many new opportunities for therapeutic treatments,” said Josephine Grima, PhD, director of research and legislative affairs at the National Marfan Foundation, in Port Washington, NY. Marfan syndrome is an autosomal dominant disorder that affects an estimated 1 in 5000 people worldwide. Affected individuals are often, but not always, very tall, slender, and loose jointed, according to the Foundation. Limbs and digits may be disproportionally long and malformations of the sternum or scoliosis may be present. The disorder also affects the cardiovascular system, eyes, skin, and nervous system. If left untreated, individuals with Marfan syndrome may develop aortic dissections and many die before age 40. However, with early diagnosis and proper management, individuals can have nearly normal lifespans. Current therapies for Marfan syndrome aim to decrease stress on the aorta. Intervention strategies include the use of -blockers and certain exercise restrictions to reduce cardiovascular stress, said Harry C. Dietz, MD, director of the William S. Smilow Center for Marfan Syndrome Research at Johns Hopkins University School of Medicine, in Baltimore. Physicians also closely monitor the condition of the aortas of individuals with Marfan syndrome and make surgical corrections when there is a risk of rupture.

Correction of a mineralization defect by overexpression of a wild-type cDNA for COL1A1 in marrow stromal cells (MSCs) from a patient with osteogenesis imperfecta: a strategy for rescuing mutations that produce dominant-negative protein defects

Gene therapy for dominant-negative disorders presents a more difficult challenge than gene therapy for recessive disorders, since even partial replacement of a protein for a recessive disorder can reverse symptoms. Osteogenesis imperfecta (OI) has frequently served as a model disorder for dominant-negative defects of structural proteins. The disease is caused by mutations in type I collagen (COL1A1), the major structural component of bone, skin and other connective tissues. The severity of the phenotype is largely dependent on the ratio of normal to mutant type I procollagen synthesized by cells. Recently, attempts have been made to develop strategies for cell and gene therapies using the adult stem cells from bone marrow referred to as mesenchymal stem cells or marrow stromal cells (MSCs). In this study, we used MSCs from a patient with type III OI who was heterozygous for an IVS 41A+4C mutation in COL1A1. A hybrid genomic / cDNA construct of COL1A1 was transfected into the MSCs and the transfectants were expanded over a 200-fold. Transfected MSCs showed increased expression of the wild-type mRNA and protein. In vitro assays demonstrated that the transfected cells more efficiently differentiated into mineralizing cells. The results indicated that it is possible to overexpress COL1A1 cDNA in OI MSCs and thereby to correct partially the dominant-negative protein defect.

Defects in extracellular matrix structural proteins in the osteochondrodysplasias.

Mutations in the genes that encode structural proteins of the extracellular matrix affect one or more steps in the diverse set of coordinated events necessary for ordered skeletal development. Depending on the role of the gene product and the severity of the defect, disruption of endochondral ossification and linear growth, the structural integrity and stability of articular cartilage, and/or mineralization can occur. Several themes have emerged from the molecular dissection of these disorders; most of the osteochondrodysplasias that result from defects in structural proteins are inherited in an autosomal dominant fashion; a spectrum of related clinical phenotypes can be produced by distinct mutations in the same gene; haploinsufficiency for the gene product usually produces a milder clinical phenotype than do mutations resulting in synthesis of structurally abnormal proteins. For structural defects, a dominant-negative effect resulting from presence of the abnormal protein in the matrix appears to be the primary determinant of phenotype. Secondary effects on extracellular matrix protein structure can result from defects in post-translational maturation, including hydroxylation, sulfation and proteolytic cleavage, and produce distinct osteochondrodysplasias. Overall, the inherited disorders of skeletogenesis have revealed the exquisite sensitivity of the architecture of the extracellular matrix to the quantity and quality of matrix molecules.

Genetic diseases with rheumatic manifestations in children.

Many nonrheumatic diseases of childhood present with musculoskeletal abnormalities. A significant proportion of these disorders have a genetic basis, many involving defects in structural proteins of the connective tissue. Chief among these are collagen mutations resulting in spondyloepiphyseal dysplasias and Ehlers-Danlos syndrome, as well as fibrillin defects associated with Marfan's syndrome. A variety of other chromosomal anomalies are associated with musculoskeletal abnormalities, and may result from as yet unidentified connective tissue defects. In addition, metabolic diseases may result in findings of hyper- or hypomobility, or carpal tunnel syndrome. Helpful clinical clues to identify nonrheumatologic musculoskeletal disease, as well as recent advances in our understanding of the genetic basis of several of these disorders, are reviewed here.

The Childhood Muscular Dystrophies: Diseases Sharing a Common Pathogenesis of Membrane Instability

New observations demonstrate that several childhood forms of muscular dystrophy share a common pathogenesis. In muscle, dystrophin occurs as part of a membrane complex (dystrophin-glycoprotein) linking the cytoskeleton to the basal lamina. In Duchenne muscular dystrophy, dystrophin deficiency disrupts the linkage of the integral glycoproteins of the sarcolemma and leads to muscle fiber necrosis. In severe childhood autosomal recessive muscular dystrophy, a selective deficiency of adhalin (50-kd glycoprotein) also causes dysfunction of the dystrophin-glycoprotein complex. Most recently, a form of congenital muscular dystrophy demonstrates deficiency of laminin M (merosin) further demonstrating that sarcolemmal instability results from defects in structural proteins of the basal lamina. Animal models have been identified also demonstrating defects in specific proteins linking the subsarcolemmal cytoskeleton to the extracellular matrix. The mdx mouse has a defect in the gene encoding dystrophin. The cardiomyopathic hamster shows a specific deficiency of adhalin in skeletal muscle. The dy/dy mouse has been found deficient in merosin. These animal models will help researchers to understand their human counterparts and provide a system for testing therapeutic strategies.

Genetically Induced Abnormalities of Epidermal Differentiation and Ultrastructure in Ichthyoses and Epidermolyses: Pathogenesis, heterogeneity, Fetal Manifestation, and Prenatal Diagnosis

Comparative ultrastructural investigations on the pathomorphogenesis of inherited ichthyoses and epidermolyses have shown that such heterogeneous skin disorders may serve as model systems for genetic interactions with developmental processes, such as keratinization, or functional systems, such as dermal-epidermal junctional integrity. Most interesting from the morphologic point of view are dominantly inherited skin disorders in the ichthyosis and epidermolysis bullosa groups in which primary structural defects of structural proteins have been demonstrated that seem to be under the direct control of the mutant gene. Such structural abnormalities concern keratohyalin in autosomal-dominant ichthyosis vulgaris, the tonofilament system in hystrix-like ichthyoses, and the anchoring fibrils in dominant dystrophic epidermolyses. Taking bullous congenital ichthyosiform erythroderma (epidermolytic hyperkeratosis) as a central example, we discuss the stability of such structural defects, the heterogeneity in the ultrastructural abnormalities of clinically closely similar entities (ichthyosis hystrix Curth-Macklin, congenital reticulate ichthyosiform erythroderma), and, in the latter keratinization disorder, the presence of an unusual filament system of unknown biochemical composition in the abnormal keratinocytes. Expression of mutant genes during fetal life and fetal manifestation of such abnormalities are a precondition for the prenatal diagnosis of genetic skin disorders (bullous ichthyosiform erythroderma, epidermolysis bullosa dystrophica Hallopeau-Siemens, Herlitz syndrome). Finally, problems related to the differentiation of mutant keratinocytes and of amniotic fluid cells of fetuses at risk of genetic skin disorders under the in vitro conditions of primary cell cultures are briefly discussed.

Electron microscopy in the early diagnosis of genetic disorders of the skin.

Electron microscopy is shown to represent an effective tool in the early diagnosis of genetic disorders. On the basis of ultrastructural findings in various dominant and recessive types of ichthyoses and epidermolyses, defects of structural proteins of the skin proved to form the main intrinsic pathogenetic feature of some dominantly inherited types whereas quantitative impairments characterize their closely resembling recessive counterparts. Most of the diseases concerned severely disable the involved patients. Early diagnosis is therefore of high importance. In those cases where an exact diagnosis in newborn children is difficult or impossible with respect to their clinical features, electron microscopy provides the clinician with reliable and significant criteria to differentiate between closely resembling entities.

Viral Gene Functions Expressed and Detected by Temperature-sensitive Mutants of Herpes Simplex Virus

The expression of HSV-specific gene functions by 22 ts mutants of HSV-1 in 15 complementation groups and 8 ts mutants of HSV-2 in 7 complementation groups has been studied at the nonpermissive temperature. Four cistrons of HSV-1 and three cistrons of HSV-2 with defects in viral DNA and DAN polymerase synthesis were identified. DNA-mutants of HSV-1 revealed a greater alteration in HSV polypeptide synthesis and viral assembly than DNA- mutants of HSV-2. Mutants with apparent defects in structural proteins have been identified for both HSV-1 and HSV-2 as demonstrated by their increased themolability. The general organization of the provisional HSV-1 and HSV-2 linkage maps revealed a similarity in the arrangement of functionally related cistrons, with DNA- mutants being located on the left-hand side of each map and mutants with phenotypic properties similar to those of the wild-type virus, on the right-hand side. An early polypeptide of HSV (VP175, MW 175,000) was found to accumulate in cells infected at the nonpermissive temperature withts mutants of HSV-1 in complementation group B. The VP175 polypeptide was isolated from such cells by a combination of SDS-preparative and analytical disc gel electrophoresis. Antiserum prepared to this polypeptide was found to descriminate between HSV-1 and HSV-2 by immunofluorescence. On the other hand, type-specific gene functions of HSV-1 and HSV-2 were not demonstrated through intertypic complementation and recombination tests with heterologous mutant pairs, whereas mutually exchangeable or common gene functions were readily identified. Eight ts mutants of HSV-2 were used to detect functional HSV genes in hamster embryo cells transformed by HSV-2. Normal hamster cells and SV40-transformed hamster cells failed to support the replication of the mutants at the nonpermissive temperature. However, the replication of two mutants, defective in late functions, was significantly enhanced in two independently derived HSV-2-transformed cell lines. Thus functional HSV genetic information was detected in HSV-2-transformed cells through the use of ts mutants. Moreover, it appears that the information present in both cell lines is not only specific but involves late HSV functions.