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Biomedical subjects

J Uitto

Publications and source records attributed to J Uitto.

At least 55 records · Page 3Linked to original sources
PubMed2000

The alpha 5 chain of type IV collagen is the target of IgG autoantibodies in a novel autoimmune disease with subepidermal blisters and renal insufficiency.

We describe a novel autoimmune disease characterized by severe subepidermal bullous eruptions and renal insufficiency with IgG autoantibodies directed against the NC1 domain of the alpha5(IV) collagen chain. In vivo deposits of IgG and C3 were found along the dermal-epidermal junction of skin lesions. The identity of the target antigen was determined by immunochemical analyses of candidate antigens using the patients' autoantibodies. The patients' IgG autoantibodies reacted with a 185-kDa polypeptide that was distinguished from the known autoantigens of the extracellular matrix including type XVII collagen, type VII collagen, or the alpha3, beta3, and gamma2 chains of laminin 5. Preincubation of the serum with recombinant alpha5(IV)NC1 domain of type IV collagen abolished immunoreactivity with the 185-kDa antigen. The serum reacted specifically with the alpha5(IV)NC1, among the six NC1 domains of type IV collagen, by Western blot and enzyme-linked immunosorbent assay analyses. The patients' autoantibodies reacted with normal skin and renal glomerulus but not with skin and glomerulus of a patient with Alport syndrome in which the basement membranes are devoid of the alpha5(IV) collagen chain. This study provided for the first time unambiguous evidence for the alpha5(IV) collagen chain as the target antigen in a novel autoimmune disease characterized by skin and renal involvement.

Autoantibodies↗
PubMed2000

Pseudoxanthoma elasticum: mutations in the MRP6 gene encoding a transmembrane ATP-binding cassette (ABC) transporter.

Pseudoxanthoma elasticum (PXE), the prototypic heritable connective tissue disorder affecting the elastic structures in the body, manifests with cutaneous, ophthalmologic, and cardiovascular findings, with considerable morbidity and mortality. The molecular basis of PXE has remained unknown, but the disease locus has recently been mapped to an approximately 500-kb interval on chromosome 16p13.1, without evidence for locus heterogeneity. In this study, we report pathogenetic mutations in MRP6, a member of the ABC transporter gene family, in eight kindreds with PXE. The mutation detection strategy consisted of heteroduplex scanning of coding sequences in the MRP6 gene, which were amplified by PCR by using genomic DNA as template, followed by direct nucleotide sequencing. A total of 13 mutant MRP6 alleles were disclosed in the eight probands with PXE. These genetic lesions consisted of either single base pair substitutions resulting in missense, nonsense, or splice site mutations, or large deletions resulting in allelic loss of the MRP6 locus. Examination of clinically unaffected family members in four multiplex families identified heterozygous carriers, consistent with an autosomal recessive inheritance pattern. Collectively, identification of mutations in the MRP6 gene provides the basis to examine the pathomechanisms of PXE and allows development of DNA-based carrier detection, prenatal testing, and preimplantation genetic diagnosis in families with a history of this disease.

ATP-Binding Cassette Transporters↗
PubMed2000

Ubinuclein, a novel nuclear protein interacting with cellular and viral transcription factors.

The major target tissues for Epstein-Barr virus (EBV) infection are B lymphocytes and epithelial cells of the oropharyngeal zone. The product of the EBV BZLF1 early gene, EB1, a member of the basic leucine-zipper family of transcription factors, interacts with both viral and cellular promoters and transcription factors, modulating the reactivation of latent EBV infection. Here, we characterize a novel cellular protein interacting with the basic domains of EB1 and c-Jun, and competing of their binding to the AP1 consensus site. The transcript is present in a wide variety of human adult, fetal, and tumor tissues, and the protein is detected in the nuclei throughout the human epidermis and as either grainy or punctuate nuclear staining in the cultured keratinocytes. The overexpression of tagged cDNA constructs in keratinocytes revealed that the NH(2) terminus is essential for the nuclear localization, while the central domain is responsible for the interaction with EB1 and for the phenotype of transfected keratinocytes similar to terminal differentiation. The gene was identified in tail-to-tail orientation with the periplakin gene (PPL) in human chromosome 16p13.3 and in a syntenic region in mouse chromosome 16. We designated this novel ubiquitously expressed nuclear protein as ubinuclein and the corresponding gene as UBN1.

Adult↗
PubMed2000

The protein core of the proteoglycan perlecan binds specifically to fibroblast growth factor-7.

Perlecan is a multifaceted heparan sulfate proteoglycan that is expressed not only as an intrinsic constituent of basement membranes but also as a cell-surface and pericellular proteoglycan. Perlecan functions as a ligand reservoir for various growth factors that become stabilized against misfolding or proteolysis and acts as a co-receptor for basic fibroblast growth factor by augmenting high affinity binding and receptor activation. These biological properties are mediated by the heparan sulfate moiety. Rather little is known about the protein core's mediation of functions. We have recently discovered that fibroblast growth factor-7 (FGF7) binds to perlecan protein core and that exogenous perlecan efficiently reconstitutes FGF7 mitogenic activity in perlecan-deficient cells. In this report we examined the specific binding of FGF7 to various domains and subdomains of perlecan protein core. Using several experimental approaches including overlay protein assays, radioligand binding experiments, and the yeast two-hybrid system, we demonstrate that FGF7 binds specifically to the N-terminal half of domain III and to a lesser extent to domain V, with affinity constants in the range of 60 nM. Thus, perlecan protein core should be considered a novel biological ligand for FGF7, an interaction that could influence cancer growth and tissue remodeling.

Cells, Cultured↗
PubMed2000

Molecular genetics of Meesmann's corneal dystrophy: ancestral and novel mutations in keratin 12 (K12) and complete sequence of the human KRT12 gene.

Recently, we identified the first mutations in corneal keratins K3 and K12 in families with Meesmann's corneal dystrophy (MCD). Here, we sequenced all regions of the human K12 gene, to enable mutation detection for all exons using genomic DNA as a template. The human K12 genomic sequence spans 5919 bp and consists of eight exons. A microsatellite dinucleotide repeat was identified within intron 3, which was highly polymorphic and which we developed for use in genotype analysis. In addition, two mutations in the helix initiation motif of K12 were found in families with MCD. A novel mutation was detected in an American kindred, 410T-->C, which predicts the amino acid substitution M129T. In a German family, mutation 428G-->C was identified, predicting amino acid change R135T. The latter mutation was identical to that which we identified in the original kindred described by Meesmann. Using the intragenic microsatellite polymorphism in K12 and additional flanking markers, we were able to show that this family shares a common haplotype with the original Meesmann kindred. These results strongly imply that R135T represents an ancestral mutation in the German population. Both mutations occur in the highly conserved helix initiation motif of the K12 polypeptide. A total of eight mutations have now been reported in the K12 gene.

Corneal Dystrophies, Hereditary↗
PubMed2000

A 500-kb region on chromosome 16p13.1 contains the pseudoxanthoma elasticum locus: high-resolution mapping and genomic structure.

We have recently mapped the genetic defect underlying pseudoxanthoma elasticum (PXE), an inherited disorder characterized by progressive calcification of elastic fibers in skin, eye, and cardiovascular system, to chromosome 16p 13.1. Here we report further data on the fine-mapping and genomic structure of this locus. Haplotype analysis of informative PXE families narrowed the locus to an interval of less than 500 kb located between markers D16B9621 and D16S764. Three overlapping YAC clones were found to cover this region through YAC-STS content mapping. An overlapping BAC contig was then constructed to cover this interval and the surrounding region. About 80% of this chromosomal region has been fully sequenced using the BAC shotgun technique. Gene content and sequence analysis predicted four genes (MRP1, MRP6, PM5, and a novel transcript) and two pseudogenes (ARA and PKDI) within this interval. By screening a somatic cell hybrid panel we were able to precision-map the breakpoint of Cy185 and the starting point of a chromosomal duplication within 20 kb of BAC A962B4. The present data further refine the localization of PXE, provide additional physical cloning resources, and will aid in the eventual identification of the genetic defect causing PXE.

Adult↗
PubMed2000

A de novo glycine substitution mutation in the collagenous domain of COL7A1 in dominant dystrophic epidermolysis bullosa.

Dystrophic epidermolysis bullosa (DEB) is a hereditary mechanobullous disorder characterized by fragility of the skin and mucous membrane due to abnormalities of anchoring fibrils. Both dominant and recessive DEB have been shown to be caused by mutations in COL7A1, the gene encoding type VII collagen which is the major component of anchoring fibrils. De novo mutation in dominant DEB is rare. In this study, we report a novel de novo glycine substitution mutation in COL7A1 in a Chinese female patient presenting with mild DEB. In search of the mutation, we scanned the entire COL7A1 using polymerase chain reaction (PCR) amplification of all exons of COL7A1, followed by heteroduplex analysis and direct sequencing of the PCR products that exhibited heteroduplex pattern. A G-to-A transition at nucleotide position 6082 within exon 73 of COL7Al was detected. The mutation converted a glycine to an arginine (G2028R) within the triple-helical domain of type VII collagen. It was confirmed that the mutation was present only in the proband. Haplotype analyses suggested that the case arose as a de novo occurrence of autosomal dominant DEB.

Alleles↗
PubMed2000

The spectrum of mutations in erythrokeratodermias--novel and de novo mutations in GJB3.

Intercellular channels in skin are a complex and functionally diverse system formed by at least eight connexins (Cx). Our recent molecular studies implicating Cx defects in inherited skin disorders emphasize the critical role of this signaling pathway in epidermal differentiation. Erythrokeratodermia variabilis (EKV) is an autosomal dominant genodermatosis with a striking phenotype characterized by the independent occurrence of transient localized erythema and hyperkeratosis. The disease maps to 1p34-p35, and recently we identified the causative gene GJB3 encoding Cx31. We have now investigated GJB3 in two families and three sporadic cases with EKV, and report three new heterozygous mutations. In a sporadic case, we detected a mutation leading to substitution of a conserved phenylalanine (F137L) in the third transmembrane domain, which likely interferes with the proper assembly or gating properties of connexons. In another family, all three affected individuals carried two distinct mutations on the same GJB3 allele. However, only a de novo heterozygous missense mutation replacing arginine 42 with proline (R42P) co-segregated with the disease, while a 12 bp deletion predicted to eliminate four amino acid residues in the variable carboxy terminal domain of Cx31 was also found in clinically unaffected relatives but not in 90 unaffected controls. Including the previously published mutations, in toto, five different missense mutations have now been detected in 6 out of 17 families investigated by our laboratory, all of which presumably affect the cytoplasmic amino terminal and transmembrane domains of Cx31. In contrast, two mutations linked to progressive high-tone hearing impairment were located in the second extracellular domain, suggesting that the character and position of Cx mutations determine their phenotypic expression in different tissues. However, the phenotypic spectrum of GJB3 mutations seems not to include progressive symmetric erythrokeratodermia, another dominant genodermatosis with overlapping features, since no mutations were found in six unrelated families tested.

Connexins↗
PubMed2000

Lichen planus pemphigoides with IgG autoantibodies to the 180 kd bullous pemphigoid antigen (type XVII collagen).

We describe a 75-year-old patient with pruritic papules on her trunk and extremities, typical of lichen planus, who later experienced subepidermal blisters. These clinical features are consistent with lichen planus pemphigoides. Immunofluorescence of perilesional skin showed linear deposits of C3 along the dermoepidermal junction. Circulating IgG autoantibodies were found to be directed against an epidermal component of the dermoepidermal junction because the patient's serum labeled the epidermal side of 1 mol/L NaCl-split skin. The patient's IgG autoantibodies were directed exclusively against the 180 kd bullous pemphigoid antigen (BPAg2, type XVII collagen) detected in human keratinocyte lysate by Western blot assay. No reactivity was found against the 230 kd bullous pemphigoid antigen, type VII collagen, or the laminin-5 subunits. This study demonstrates that BPAg2 is recognized, not only by bullous pemphigoid sera, but also by lichen planus pemphigoides sera. Our findings attest to the similarity of immunopathology in these two subepidermal blistering skin diseases.

Aged↗
PubMed2000

Cutaneous gene therapy. Principles and prospects.

As investigators continue to close the gap between basic research and clinical science, gene therapy is becoming of increasing interest to the dermatologist. Most notably, recent advances in gene-based cancer therapy, DNA vaccination, and molecular pharmacology have opened new avenues for investigation beyond those of the traditional gene replacement applications. Different gene delivery systems are currently being tested, each with specific advantages and disadvantages. This article summarizes some of the principles of gene therapy and its applications to cutaneous diseases.

Genetic Therapy↗
PubMed2000

Cytokine modulation of extracellular matrix gene expression: relevance to fibrotic skin diseases.

Fibrotic skin diseases demonstrate a spectrum of phenotypic manifestations with a unifying histopathologic hallmark, i.e. the accumulation of collagen in the lesional skin. Mechanistically, collagen deposition could result either from enhanced biosynthetic activity or reduced rate of degradation, thus leading to an imbalance in physiological turnover of collagen in the dermis. This overview summarizes the mechanisms of regulation of collagen gene expression in fibroblasts as exemplified by cytokine modulation. This summary also provides evidence in support of the notion that transcriptional activation of collagen gene expression is the underlying mechanism leading to development of fibrotic cutaneous lesions, as documented in keloids, a prototypic example of cutaneous fibrosis.

Animals↗
PubMed2000

Novel keratin 16 mutations and protein expression studies in pachyonychia congenita type 1 and focal palmoplantar keratoderma.

Pachyonychia congenita type 1 (PC-1) is an autosomal dominant ectodermal dysplasia characterized by nail dystrophy, focal non-epidermolytic palmoplantar keratoderma (FNEPPK) and oral lesions. We have previously shown that mutations in keratin 16 (K16) cause fragility of specific epithelia resulting in phenotypes of PC-1 or FNEPPK alone. Here, we report 2 novel mutations in K16 causing distinct phenotypes. A heterozygous missense mutation (L124R) was detected in a kindred with PC-1. In a family where mild FNEPPK was the only phenotype, a 23 bp deletion and a separate 1 bp deletion downstream were found in exon 6: [1244-1266del; 1270delG]. At the protein level, these mutations remove 8 residues and substitute 2 residues in the helix termination motif (HTM) of the K16 polypeptide. The HTM sequence is conserved in all known intermediate filament proteins and for convenience, this complex mutation was designated deltaHTM. Transient expression of K16 cDNAs carrying either the L124R or the deltaHTM mutation in epithelial cell line PtK2 produced aggregation of the keratin cytoskeleton. However, the aggregates observed with the deltaHTM mutation were morphologically different and appeared to be less disruptive to the endogenous cytoskeleton. Therefore, loss of the HTM sequence may render this mutant K16 less capable of contributing to filament assembly and decrease its dominant-negative effect, resulting in the milder FNEPPK phenotype.

Base Sequence↗
PubMed2000

Cloning of the mouse desmoglein 3 gene (Dsg3): interspecies conservation within the cadherin superfamily.

Desmoglein 3 is a cadherin-like calcium-dependent cell adhesion molecule expressed primarily in suprabasal keratinocytes of the epidermis. In this study, we have cloned the full-length cDNA and characterized the entire gene structure for the mouse desmoglein 3 gene (Dsg3). Isolation of overlapping cDNA clones, together with 5' and 3' rapid amplification of cDNA ends (RACE), allowed delineation of the entire coding sequence. The transcriptional initiation site was confirmed by primer extension and reverse transcription polymerase chain reaction analysis. The entire cDNA consisted of 6407 bp with an open reading frame of 2979 bp, and the deduced polypeptide contained 993 amino acids. Comparison of mouse and human desmoglein 3 amino acid sequences demonstrated 85.6% homology. Computer analysis suggested the presence of a transmembrane segment, 5 potential calcium binding sites, and a RAL motif which corresponds to the HAV motif, the potential site for homophilic interaction of typical cadherins. The mouse desmoglein 3 gene consisted of 15 exons in chromosome 18. Comparison of the intron-exon organization of Dsg3 with various cadherins from different species revealed remarkable conservation. This relatively high level of conservation both at the protein and genomic level suggests that desmoglein 3 plays an important role in keratinocyte cell-cell adhesion.

Amino Acid Sequence↗
PubMed2000

Mutation report: complete paternal uniparental isodisomy of chromosome 1: a novel mechanism for Herlitz junctional epidermolysis bullosa.

Uniparental disomy denotes a situation when an individual has inherited two copies of a specific chromosome from a single parent. Uniparental disomy has been demonstrated to be involved in the pathogenesis of recessively inherited diseases in rare cases. Here we report a patient of Japanese origin with Herlitz junctional epidermolysis bullosa (OMIM no. 226700), who died at the age of 8 mo from complications of the disease. The mutation analysis revealed that the proband was homozygous for a nonsense mutation C553X in the LAMC2 gene encoding the gamma2 chain of laminin 5. The father was a heterozygous carrier of this mutation whereas the mother had two normal alleles of this gene. The patient showed homozygosity for 15 known intragenic polymorphisms in the LAMC2 gene. Furthermore, genotype analysis, performed from the parents and the proband, using 16 microsatellite markers spanning the entire chromosome 1, revealed that the patient was homozygous for all markers tested, and that these alleles originated from the father. Among the 16 markers, eight were fully informative for the absence of the maternal chromosome 1 in the proband, suggesting that the patient had complete paternal isodisomy of this chromosome. Thus, the Herlitz junctional epidermolysis bullosa phenotype in this patient is caused by homozygous LAMC2 mutation C553X that is of paternal origin and results from nondisjunction and uniparental disomy involving monosomy rescue. This is a novel mechanism resulting in Herlitz junctional epidermolysis bullosa and has implications for assessment of the risk in subsequent pregnancies.

Base Sequence↗
PubMed2000

Herlitz junctional epidermolysis bullosa: novel and recurrent mutations in the LAMB3 gene and the population carrier frequency.

Herlitz junctional epidermolysis bullosa is a heritable bullous disease caused by mutations found primarily in the b3 chain of laminin 5 (LAMB3). In this study, we examined the LAMB3 gene for mutations in 22 Herlitz junctional epidermolysis bullosa families, and identified 15 distinct mutations, eight of them previously unreported, bringing the total number of distinct Herlitz junctional epidermolysis bullosa mutations in LAMB3 to 35. Examination of the mutation database revealed several recurrent mutations that have been reported, as well as six previously unreported. All recurrent mutations may be readily detected by polymerase chain reaction of genomic DNA and restriction endonuclease digestion. Mutation screening and prenatal diagnosis of families at risk may be expedited by molecular testing for these recurrent mutations prior to screening the entire gene. Finally, the U.S. population carrier risk for Herlitz junctional epidermolysis bullosa and all variants of junctional epidermolysis bullosa was calculated to be one in 781 and one in 350, respectively, while the overall epidermolysis bullosa carrier frequency was calculated to be one in 113. These data allow accurate testing, counseling, and risk calculation for nuclear families, as well as extended family members at risk for junctional epidermolysis bullosa.

Alleles↗