Inborn errors of metabolism (IEMs) comprise a diverse group of monogenic disorders caused by enzyme deficiencies that result either in a toxic accumulation of metabolic intermediates or a shortage of ...essential end-products. Certain IEMs, like phenylketonuria (PKU), necessitate stringent dietary intervention that could lead to microbiome dysbiosis, thereby exacerbating the clinical phenotype. The objective of this systematic review was to examine the impact of PKU therapies on the intestinal microbiota. This research was conducted following the PRISMA Statement, with data from PubMed, Scopus, ScienceDirect, and Web of Science. A total of 18 articles meeting the inclusion criteria were published from 2011 to 2022. Significant reductions in several taxonomic groups in individuals with PKU when compared to the control group were detected in a quantitative analysis conducted across seven studies. The meta-analysis synthesis indicates a contrast in biodiversity between PKU subjects and the control population. Additionally, the meta-regression results, derived from the Bacillota/Bacteroidota ratio data, suggest a potential influence of diet in adult PKU populations (
= 0.004). It is worth noting that the limited number of studies calls for further research and analysis in this area. Our findings indicate the necessity of enhancing understanding of microbiota variability in reaction to treatments among PKU subjects to design tailored therapeutic and nutritional interventions to prevent complications resulting from microbiota disruption.
Hereditary sensory and autonomic neuropathies (HSAN) are clinically and genetically heterogeneous disorders, characterized by a progressive sensory neuropathy often complicated by ulcers and ...amputations, with variable motor and autonomic involvement. Several pathways have been implicated in the pathogenesis of neuronal degeneration in HSAN, while recent observations point to an emerging role of cytoskeleton organization and function. Here, we report novel biallelic mutations in the DST gene encoding dystonin, a large cytolinker protein of the plakin family, in an adult form of HSAN type VI. Affected individuals harbored the premature termination codon variant p.(Lys4330*) in trans with the p.(Ala203Glu) change affecting a highly conserved residue in an isoform‐specific N‐terminal region of dystonin. Functional studies showed defects in actin cytoskeleton organization and consequent delayed cell adhesion, spreading and migration, while recombinant p.Ala203Glu dystonin loses the ability to bind actin. Our data aid in the clinical and molecular delineation of HSAN‐VI and suggest a central role for cell‐motility and cytoskeletal defects in its pathogenesis possibly interfering with the neuronal outgrowth and guidance processes.
Dystonin (encoded by DST) is one of the largest proteins in humans and member of the plakin family of cytoskeleton linker protein.
Mutations affecting its neuronal isoforms have been so far reported in only 2 families with highly discordant phenotypes of Hereditary Sensory and Autonomic Neuropathy (HSAN type VI).
Here, we identified novel variants in DST as the genetic defects of HSAN‐VI and contribute to its clinical and molecular definition. Functional studies showed altered cell‐motility and cytoskeletal defects providing novel pathogenic mechanisms.
Lympho-epithelial Kazal-type-related inhibitor (LEKTI) is the defective protein of the ichthyosiform condition Netherton syndrome (NS). Strongly expressed in the most differentiated epidermal layers, ...LEKTI is a serine protease inhibitor synthesized as three different high-molecular-weight precursors, which are rapidly processed into shorter fragments and secreted extracellularly. LEKTI polypeptides interact with several proteases to regulate skin barrier homeostasis as well as inflammatory and/or immunoallergic responses. Here, by combining antibody mapping, N-terminal sequencing, and site-specific mutagenesis, we defined the amino-acid sequence of most of the LEKTI polypeptides physiologically generated in human epidermis. We also identified three processing intermediates not described so far. Hence, a proteolytic cascade model for LEKTI activation is proposed. We then pinpointed the most effective fragments against the desquamation-related kallikreins (KLKs) and we proved that LEKTI is involved in stratum corneum shedding as some of its polypeptides inhibit the KLK-mediated proteolysis of desmoglein-1. Finally, we quantified the individual LEKTI fragments in the uppermost epidermis, showing that the ratios between LEKTI polypeptides and active KLK5 are compatible with a fine-tuned inhibition. These findings are relevant both to the understanding of skin homeostasis regulation and to the design of novel therapeutic strategies for NS.
Measles is characterized by fever and a maculopapular skin rash, which is accompanied by immune clearance of measles virus (MV)-infected cells. Histopathological analyses of skin biopsies from humans ...and non-human primates (NHPs) with measles rash have identified MV-infected keratinocytes and mononuclear cells in the epidermis, around hair follicles and near sebaceous glands. Here, we address the pathogenesis of measles skin rash by combining data from experimentally infected NHPs, ex vivo infection of human skin sheets and in vitro infection of primary human keratinocytes. Analysis of NHP skin samples collected at different time points following MV inoculation demonstrated that infection in the skin precedes onset of rash by several days. MV infection was detected in lymphoid and myeloid cells in the dermis before dissemination to the epidermal leukocytes and keratinocytes. These data were in good concordance with ex vivo MV infections of human skin sheets, in which dermal cells were more targeted than the epidermal cells. To address viral dissemination to the epidermis and to determine whether the dissemination is receptor-dependent, we performed experimental infections of primary keratinocytes collected from healthy donors. These experiments demonstrated that MV infection of keratinocytes is mainly nectin-4-dependent, and differentiated keratinocytes, which express higher levels of nectin-4, are more susceptible to MV infection than proliferating keratinocytes. Based on these data, we propose a model to explain measles skin rash: migrating MV-infected lymphocytes initiate the infection of dermal skin-resident CD150+ immune cells. The infection is subsequently disseminated from the dermal papillae to nectin-4+ keratinocytes in the basal epidermis. Lateral spread of MV infection is observed in the superficial epidermis, most likely due to the higher level of nectin-4 expression on differentiated keratinocytes. Finally, MV-infected cells are cleared by infiltrating immune cells, causing hyperemia and edema, which give the appearance of morbilliform skin rash.
Regulation of Survivin Function by Hsp90 Fortugno, Paola; Beltrami, Elena; Plescia, Janet ...
Proceedings of the National Academy of Sciences - PNAS,
11/2003, Volume:
100, Issue:
24
Journal Article
Peer reviewed
Open access
Pathways controlling cell proliferation and cell survival require flexible adaptation to environmental stresses. These mechanisms are frequently exploited in cancer, allowing tumor cells to thrive in ...unfavorable milieus. Here, we show that Hsp90, a molecular chaperone that is central to the cellular stress response, associates with survivin, an apoptosis inhibitor and essential regulator of mitosis. This interaction involves the ATPase domain of Hsp90 and the survivin baculovirus inhibitor of apoptosis repeat. Global suppression of the Hsp90 chaperone function or targeted Ab-mediated disruption of the survivin-Hsp90 complex results in proteasomal degradation of survivin, mitochondrial-dependent apoptosis, and cell cycle arrest with mitotic defects. These data link the cellular stress response to an antiapoptotic and mitotic checkpoint maintained by survivin. Targeting the survivin-Hsp90 complex may provide a rational approach for cancer therapy.
Ectodermal dysplasias form a large disease family with more than 200 members. The combination of hair and tooth abnormalities, alopecia, and cutaneous syndactyly is characteristic of ectodermal ...dysplasia-syndactyly syndrome (EDSS). We used a homozygosity mapping approach to map the EDSS locus to 1q23 in a consanguineous Algerian family. By candidate gene analysis, we identified a homozygous mutation in the
PVRL4 gene that not only evoked an amino acid change but also led to exon skipping. In an Italian family with two siblings affected by EDSS, we further detected a missense and a frameshift mutation.
PVRL4 encodes for nectin-4, a cell adhesion molecule mainly implicated in the formation of cadherin-based adherens junctions. We demonstrated high nectin-4 expression in hair follicle structures, as well as in the separating digits of murine embryos, the tissues mainly affected by the EDSS phenotype. In patient keratinocytes, mutated nectin-4 lost its capability to bind nectin-1. Additionally, in discrete structures of the hair follicle, we found alterations of the membrane localization of nectin-afadin and cadherin-catenin complexes, which are essential for adherens junction formation, and we found reorganization of actin cytoskeleton. Together with cleft lip and/or palate ectodermal dysplasia (CLPED1, or Zlotogora-Ogur syndrome) due to an impaired function of nectin-1, EDSS is the second known “nectinopathy” caused by mutations in a nectin adhesion molecule.
Significance Despite exhibiting different phenotypes, the UV-sensitive syndromes trichothiodystrophy (TTD) and xeroderma pigmentosum (XP) result from the same mutated genes encoding specific subunits ...of the DNA-repair/transcription factor TFIIH. The widely accepted notion is that XP cancer proneness results from mutations interfering with DNA repair, whereas TTD clinical hallmarks (namely, hair anomalies, physical and mental retardation, and premature aging) are because of transcriptional alterations. The present study identifies a TTD-specific overexpression of matrix metalloproteinase 1 , leading to collagen I degradation in patient skin. This finding explains the clinical features distinguishing TTD from XP (i.e. bone alterations, pregnancy abnormalities and likely lack of skin cancer despite the accumulation of unrepaired DNA lesions) and the features that TTD shares with osteogenesis imperfecta caused by COL1 mutations.
Mutations in the XPD subunit of the DNA repair/transcription factor TFIIH result in distinct clinical entities, including the cancer-prone xeroderma pigmentosum (XP) and the multisystem disorder trichothiodystrophy (TTD), which share only cutaneous photosensitivity. Gene-expression profiles of primary dermal fibroblasts revealed overexpression of matrix metalloproteinase 1 ( MMP-1 ), the gene encoding the metalloproteinase that degrades the interstitial collagens of the extracellular matrix (ECM), in TTD patients mutated in XPD compared with their healthy parents. The defect is observed in TTD and not in XP and is specific for fibroblasts, which are the main producers of dermal ECM. MMP-1 transcriptional up-regulation in TTD is caused by an erroneous signaling mediated by retinoic acid receptors on the MMP-1 promoter and leads to hypersecretion of active MMP-1 enzyme and degradation of collagen type I in the ECM of cell/tissue systems and TTD patient skin. In agreement with the well-known role of ECM in eliciting signaling events controlling cell behavior and tissue homeostasis, ECM alterations in TTD were shown to impact on the migration and wound-healing properties of patient dermal fibroblasts. The presence of a specific inhibitor of MMP activity was sufficient to restore normal cell migration, thus providing a potential approach for therapeutic strategies. This study highlights the relevance of ECM anomalies in TTD pathogenesis and in the phenotypic differences between TTD and XP.
Variably reduced expression of the basement membrane component laminin-332 (α3aβ3γ2) causes junctional epidermolysis bullosa generalized intermediate (JEB-GI), a skin fragility disorder with an ...increased susceptibility to squamous cell carcinoma (SCC) development in adulthood. Laminin-332 is highly expressed in several types of epithelial tumors and is central to signaling pathways that promote SCC tumorigenesis. However, laminin-332 mutations and expression in individuals affected by JEB-GI and suffering from recurrent SCCs have been poorly characterized. We studied a JEB-GI patient who developed over a hundred primary cutaneous SCCs. Molecular analysis combined with gene expression studies in patient skin and primary keratinocytes revealed that the patient is a functional hemizygous for the p.Cys1171* mutant allele which is transcribed in a stable mRNA encoding for a β3 chain shortened of the last two C-terminal amino acids (Cys1171-Lys1172). The lack of the Cys1171 residue involved in the C-terminal disulphide bond to γ2 chain did not prevent assembly, secretion, and proteolytic processing of the heterotrimeric molecule. Immunohistochemistry of SCC specimens revealed accumulation of mutant laminin-332 at the epithelial-stromal interface of invasive front. We conclude that the C-terminal disulphide bond is a structural element crucial for laminin-332 adhesion function in-vivo. By saving laminin-332 amount, processing, and signaling role the p.Cys1171* mutation may allow intrinsic pro-tumorigenic properties of the protein to be conveyed, thus contributing to invasiveness and recurrence of SCCs in this patient.
Circulating anti-type VII collagen autoantibodies are frequently detected in patients with recessive dystrophic epidermolysis bullosa (RDEB). However, evidence supporting their pathogenic role in ...inducing epidermolysis bullosa acquisita (EBA) has been provided for only one individual with dominant dystrophic epidermolysis bullosa (DDEB). We describe here a patient who presented with dystrophic toenails since early childhood and developed trauma-induced skin blisters and oral erosions at age 26 years. Direct immunofluorescence showed IgG deposits with a u-serrated pattern along the cutaneous basement membrane zone, while no change in the expression of collagen VII could be detected by antigen mapping. High-titre anti-collagen VII antibodies were detected by enzyme-linked immunoassay (ELISA). In parallel, sequencing of epidermolysis bullosa (EB) genes identified compound heterozygous COL7A1 missense c.410G>A (p.Arg137Gln) and splicing c.3674C>T (p.Ala1225_Gln1241del) mutations, previously unrecognized in dystrophic epidermolysis bullosa (DEB). Thus, our patient had RDEB "nails-only" and developed mechanobullous EBA in adulthood. These data support a pathogenic role of circulating autoantibodies to collagen VII in inducing EBA in selected patients with DEB. Unforeseen worsening of skin symptoms in DEB should prompt laboratory investigations for EBA.
Nectins are immunoglobulin‐like cell adhesion molecules mainly localized in adherens junctions. The transcription factor p63 is a master regulator of gene expression in stratified epithelia and ...controls several molecular processes. As mutations in the Pvrl1 and Pvrl4 genes encoding for nectins cause genetic disorders with phenotypes similar to p63‐related syndromes, we investigated whether these proteins might be under p63 transcriptional control. Here, we show that in p63‐null skin, Pvrl1 gene expression is strongly reduced, whereas Pvrl4 expression is unaffected. In human and mouse primary keratinocytes p63 depletion leads to a specific downregulation of the Pvrl1 gene. Consistent with a direct regulation, chromatin immunoprecipitation experiments (ChIP) indicate that p63 binds to two conserved intronic Pvrl1 enhancer regions. Ankyloblepharon–ectodermal defects–cleft lip/palate (AEC) syndrome is a rare autosomal dominant disorder, caused by mutations in p63 gene, mainly characterized by skin fragility. To test whether nectins may be affected in AEC syndrome, their expression was measured in keratinocytes obtained from patients with AEC or from a conditional mouse model for AEC syndrome. Pvrl1 expression was reduced in AEC keratinocytes, consistent with impaired p63 function. Surprisingly, Pvrl4 expression was similarly affected, in parallel with decreased expression of the transcription factor Irf6. Consistent with the well‐characterized role of Irf6 in keratinocyte differentiation and its strong downregulation in AEC syndrome, Irf6 depletion caused reduced expression of Pvrl4 in wild‐type keratinocytes. Taken together, our results indicate that Pvrl1 is a bona fide target gene of the transcription factor p63, whereas Pvrl4 regulation is linked to epidermal differentiation and is under Irf6 control.
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