Biomedical subjects

Jouni Uitto

Publications and source records attributed to Jouni Uitto.

At least 19 recordsLinked to original sources

PubMed2007

Advocacy groups as research organizations: the PXE International example.

Advocacy organizations for genetic diseases are increasingly becoming involved in biomedical research, particularly translational research, in order to meet the needs of the individuals that they serve. PXE International, an advocacy organization for the disease pseudoxanthoma elasticum, provides an example of how research can be accelerated by these groups. It has adopted methods that were pioneered by other advocacy organizations, and has integrated these along with new approaches into franchizable elements. The model has been followed for other conditions and has led to the establishment of a common infrastructure to enable advocacy groups to initiate, conduct and accelerate research.

Biomedical Research↗

PubMed2007

IL-6 signaling pathway in keloids: a target for pharmacologic intervention?

Keloids are cosmetically devastating lesions with considerable morbidity. Ghazizadeh et al. document enhanced expression of IL-6 and its receptors in keloid fibroblasts, with a concomitant increase in collagen biosynthesis. Anti-IL-6 antibodies or blocking the IL-6 receptors elicits reduced collagen synthesis, suggesting a role for IL-6 in the regulation of collagen gene expression. These observations imply the feasibility of a pharmacologic platform, based on the targeting of the IL-6 signaling pathway, in keloids.

Collagen↗

PubMed2006

Epidermolysis bullosa. II. Type VII collagen mutations and phenotype-genotype correlations in the dystrophic subtypes.

BACKGROUND: The dystrophic forms of epidermolysis bullosa (DEB), a group of heritable blistering disorders, show considerable phenotypic variability, and both autosomal dominant and autosomal recessive inheritance can be recognised. DEB is derived from mutations in the type VII collagen gene (COL7A1), encoding a large collagenous protein that is the predominant, if not exclusive, component of the anchoring fibrils at the dermal-epidermal junction. METHODS: The Dystrophic Epidermolysis Bullosa Research Association Molecular Diagnostics Laboratory (Philadelphia, Pennsylvania, USA), established in 1996, has analysed more than 1000 families with different forms of epidermolysis bullosa, among them 332 families with DEB. DNA specimens were subjected to mutation analysis by polymerase chain reaction (PCR) amplification of all 118 exons and flanking intronic sequences of COL7A1, followed either by heteroduplex scanning and sequencing of the PCR products demonstrating heteroduplexes or by direct nucleotide sequencing. RESULTS: 355 mutant alleles out of the anticipated 438 (81.1%) were disclosed. Among these mutations, a total of 242 mutations were distinct and 138 were novel, previously unreported mutations. No evidence of mutations in any other gene was obtained. DISCUSSION: Examination of the mutation database suggested phenotype-genotype correlations, contributing to the improved subclassification of DEB with prognostic implications. The mutation information also forms the basis for accurate genetic counselling and prenatal diagnosis in families at risk for recurrence.

Alleles↗

PubMed2006

Naegeli-Franceschetti-Jadassohn syndrome and dermatopathia pigmentosa reticularis: two allelic ectodermal dysplasias caused by dominant mutations in KRT14.

Naegeli-Franceschetti-Jadassohn syndrome (NFJS) and dermatopathia pigmentosa reticularis (DPR) are two closely related autosomal dominant ectodermal dysplasia syndromes that clinically share complete absence of dermatoglyphics (fingerprint lines), a reticulate pattern of skin hyperpigmentation, thickening of the palms and soles (palmoplantar keratoderma), abnormal sweating, and other subtle developmental anomalies of the teeth, hair, and skin. To decipher the molecular basis of these disorders, we studied one family with DPR and four families with NFJS. We initially reassessed linkage of NFJS/DPR to a previously established locus on 17q11.2-q21. Combined multipoint analysis generated a maximal LOD score of 8.3 at marker D17S800 at a recombination fraction of 0. The disease interval was found to harbor 230 genes, including a large cluster of keratin genes. Heterozygous nonsense or frameshift mutations in KRT14 were found to segregate with the disease trait in all five families. In contrast with KRT14 mutations affecting the central alpha -helical rod domain of keratin 14, which are known to cause epidermolysis bullosa simplex, NFJS/DPR-associated mutations were found in a region of the gene encoding the nonhelical head (E1/V1) domain and are predicted to result in very early termination of translation. These data suggest that KRT14 plays an important role during ontogenesis of dermatoglyphics and sweat glands. Among other functions, the N-terminal part of keratin molecules has been shown to confer protection against proapoptotic signals. Ultrastructural examination of patient skin biopsy specimens provided evidence for increased apoptotic activity in the basal cell layer where KRT14 is expressed, suggesting that apoptosis is an important mechanism in the pathogenesis of NFJS/DPR.

Apoptosis↗

PubMed2006

A deleterious mutation in SAMD9 causes normophosphatemic familial tumoral calcinosis.

Familial tumoral calcinosis (FTC) is a rare autosomal recessive disorder characterized by the progressive deposition of calcified masses in cutaneous and subcutaneous tissues, which results in painful ulcerative lesions and severe skin and bone infections. Two major types of FTC have been recognized: hyperphosphatemic FTC (HFTC) and normophosphatemic FTC (NFTC). HFTC was recently shown to result from mutations in two different genes: GALNT3, which codes for a glycosyltransferase, and FGF23, which codes for a potent phosphaturic protein. To determine the molecular cause of NFTC, we performed homozygosity mapping in five affected families of Jewish Yemenite origin and mapped NFTC to 7q21-7q21.3. Mutation analysis revealed a homozygous mutation in the SAMD9 gene (K1495E), which was found to segregate with the disease in all families and to interfere with the protein expression. Our data suggest that SAMD9 is involved in the regulation of extraosseous calcification, a process of considerable importance in a wide range of diseases as common as atherosclerosis and autoimmune disorders.

Amino Acid Sequence↗

PubMed2006

High-affinity binding of the NC1 domain of collagen VII to laminin 5 and collagen IV.

Anchoring functions of collagen VII depend on its ability to form homotypic fibrils and to bind to other macromolecules to form heterotypic complexes. Biosensor-based binding assays were employed to analyze the kinetics of the NC1 domain-mediated binding of collagen VII to laminin 5, collagen IV, and collagen I. We showed that collagen VII interacts with laminin 5 and collagen IV with a Kd value of 10(-9) M. In contrast, the NC1-mediated binding to collagen I was weak with a Kd value of 10(-6) M. Binding assays also showed that the NC1 domain utilizes the same region to bind to both laminin 5 and collagen IV. We postulate that the ability of the NC1 domains to bind with high affinities to laminin 5 and collagen IV facilitates stabilization of the structure of the basement membrane itself and that the NC1-collagen I interaction may be less important for stabilization of the dermal-epidermal junction.

Binding Sites↗

PubMed2006

Lung development in laminin gamma2 deficiency: abnormal tracheal hemidesmosomes with normal branching morphogenesis and epithelial differentiation.

BACKGROUND: Laminin gamma2 (Lamc2), one of the polypeptides in laminin-332 (laminin-5), is prominent in the basement membrane of alveolar walls and airways of developing and adult lung. Laminins are important for lung morphogenesis and based on its localization, a function for laminin gamma2 in lung development has been hypothesized. Targeted deletion of the laminin gamma2 gene in mice results in skin blistering and neonatal death at 3-5 days after birth due to failure to thrive. METHODS: Examination of lung development in Lamc2-/- mice through 1-2 days postnatal was accomplished by morphometric analysis, lung bud culture, electron microscopy, immunohistochemical and immunofluorescence staining. RESULTS: Compared to littermate controls, Lamc2-/- lungs were similar in morphology during embryonic life. At post-natal day 1-2, distal saccules were mildly dilated by chord length measurements. Epithelial differentiation as evaluated by immunohistochemical staining for markers of ciliated cells, Clara cells, alveolar type I cells and alveolar type II cells did not reveal a difference between Lamc2-/- and littermate control lungs. Likewise, vascular development, smooth muscle cell differentiation, and elastic fiber formation looked similar, as did airway basement membrane ultrastructure. Branching morphogenesis by lung bud culture was similar in Lamc2-/- and littermate control lungs. Since laminin-332 is important for hemidesmosome formation, we examined the structure of tracheal hemidesmosomes by transmission electron microscopy. Compared to littermate controls, Lamc2-/- tracheal hemidesmosomes were less organized and lacked the increased electron density associated with the basement membrane abutting the hemidesmosome. CONCLUSION: These findings indicate that laminin gamma2 and laminin-332, despite their prominence in the lung, have a minimal role in lung development through the saccular stage.

Animals↗

PubMed2006

Transcriptional regulation and characterization of the promoter region of the human ABCC6 gene.

ABCC6, a member of the adenosine 5'-triphosphate-binding cassette family of genes, encodes multidrug resistance-associated protein 6, a putative transmembrane transporter expressed primarily in the liver and to a significantly lower extent in other tissues. Mutations in ABCC6 result in pseudoxanthoma elasticum, a multi-system heritable connective tissue disorder with variable phenotypic expression. To examine the transcriptional regulation and tissue-specific expression of this gene, we cloned 2.6 kb of human ABCC6 promoter and developed a series of 5'-deletion constructs linked to luciferase reporter gene. Transient transfections in a number of cultured cell lines of diverse origin identified a specific NF-kappaB-like sequence (-235/-226), which conferred high level of expression in HepG2 hepatoma cells, inferring liver specificity. The functionality of the promoter fragments was confirmed in vivo by tail vein injection followed by luciferase reporter assay. Testing of selected cytokines revealed that transforming growth factor (TGF)-beta upregulated, while tumor necrosis factor (TNF)-alpha and interferon (IFN)-gamma downregulated the promoter activity in HepG2 cells. The responsiveness to TGF-beta was shown to reside primarily within an Sp1/Sp3 cognate-binding site at -58 to -49. The expression of the ABCC6 promoter was also shown to be markedly enhanced by Sp1 protein, as demonstrated by cotransfection of ABCC6 promoter-luciferase constructs and an Sp1 expression vector in Drosophila SL2 cells, which are devoid of endogenous Sp1. Furthermore, four additional transcription factors, with their cognate-binding sequences present in DNA, were shown to bind the 2.6-kb promoter fragment by protein/DNA array. Collectively, the results indicate that human ABCC6 displays tissue-specific gene expression, which can be modulated by proinflammatory cytokines. These findings may have implications for phenotypic expression of heritable and acquired diseases involving abnormality in the ABCC6 gene.

Animals↗

PubMed2006

Pseudoxanthoma elasticum is a recessive disease characterized by compound heterozygosity.

Pseudoxanthoma elasticum (PXE) is caused by mutations in the ABCC6 gene. Historically, PXE has been suggested to be inherited either in an autosomal dominant or autosomal recessive manner. To determine the exact mode of inheritance of PXE and to address the question of phenotypic expression in mutation carriers, we identified seven pedigrees with affected individuals in two different generations and sequenced the entire coding region of ABCC6 in affected individuals, presumed carriers with a limited phenotype and unaffected family members. Two allelic mutations were identified in each individual with unambiguous diagnosis of PXE, as well as in those with only minimal clinical signs suggestive of PXE but with positive skin biopsy. Missense mutations were frequently detected in the latter cases. In conclusion, PXE is inherited in an autosomal recessive manner and presence of disease in two generations is due to pseudodominance.

DNA Mutational Analysis↗

PubMed2006

Molecular epidemiology of hereditary epidermolysis bullosa in a Middle Eastern population.

Epidermolysis bullosa (EB) encompasses a large group of inherited blistering skin disorders caused by mutations in at least 10 genes. Numerous studies, mainly performed in European and US families with EB, have revealed a number of characteristic epidemiological and genetic features, which form the basis for current diagnostic and counseling strategies. However, little is currently known about the molecular epidemiology of EB in Middle East populations. In the present study, we assessed 55 EB families for pathogenic sequence alterations in the 10 genes known to be associated with EB. Our results show unique EB subtype distribution and patterns of inheritance in our cohort. We also failed to detect recurrent mutations frequently encountered in Europe and the US, and did not consistently observe genotype-phenotype correlations formerly established in Western populations. Thus, the molecular epidemiology of EB in the Middle East is significantly different from that previously delineated in Europe and the US. Our data raise the possibility that similar differences may also be found in other genetically heterogeneous groups of disorders, and indicate the need for population-specific diagnostic and management approaches.

Asian People↗

PubMed2006

Pseudoxanthoma elasticum: a metabolic disease?

Pseudoxanthoma elasticum (PXE), a pleiotropic multisystem disorder affecting the skin, eyes, and cardiovascular system, is caused by mutations in the ABCC6/MRP6 expressed primarily in the liver. A question has arisen regarding the pathomechanism of PXE, particularly the "metabolic" versus the "PXE cell" hypotheses. Le Saux et al. have now provided partial support for the notion that PXE is primarily a metabolic disorder.

Elastic Tissue↗

PubMed2006

Interferon-gamma down-regulates expression of the 230-kDa bullous pemphigoid antigen gene (BPAG1) in epidermal keratinocytes via novel chimeric sequences of ISRE and GAS.

The 230-kDa bullous pemphigoid antigen (BPAG1) is an integral component of hemidesmosomes. We have previously reported that interferon-gamma (IFNgamma) inhibits the transcription of the BPAG1 gene (1). Here we investigated the target sequences of IFNgamma-signal transduction pathway in the BPAG1 promoter in epidermal keratinocytes. Transient transfections with 5'-deletion constructs of BPAG1 promoter-luciferase reporter gene plasmids in cultured normal human epidermal keratinocytes (NHEK) allowed us to narrow the DNA region containing IFNgamma inhibitory element (IGIE) to between -1 and -89, upstream from the transcription initiation site (+1). Homology search in this region identified a chimeric sequence, consisting of IFN-stimulated responsive element (ISRE) with a partial 7-bp sequence of IFNgamma activation site (GAS), as identified in the guanylate-binding protein (GBP) gene, inserted at its center. Functional analysis of IGIE, inserted in front of the heterologous thymidine kinase promoter, indicated that IGIE acts as a down-regulatory element of the promoter through IFNgamma-dependent signal pathway. Transient transfection studies with BPAG1 promoter-reporter gene constructs containing mutated IGIE (with TT to GG transversions in the region of 5'ISRE, GAS, and 3'ISRE) demonstrated that disruption of the ISRE sequences, but not GAS, markedly suppressed the BPAG1 basal promoter activity and resulted in attenuated IFNgamma response in keratinocytes. Our findings provide novel insight into the mechanism of IFNgamma regulation in keratinocyte differentiation and proliferation.

Base Sequence↗

PubMed2006

Extracellular matrix protein 1 inhibits the activity of matrix metalloproteinase 9 through high-affinity protein/protein interactions.

Extracellular matrix protein 1 (ECM1), an approximately 85-kDa glycoprotein with broad tissue distribution, harbors mutations in lipoid proteinosis (LP), a heritable disease characterized by reduplication of basement membranes and hyalinization of dermis, associated with neurologic disorders. The mechanisms leading from ECM1 mutations to LP phenotype are unknown. In this study, we explored ECM1 protein-protein interactions utilizing yeast two-hybrid genetic screen of human placental library, which identified nine interacting proteins, including matrix metalloproteinase 9 (MMP9). The interactions were confirmed by beta-galactosidase assay with isolated clones and by co-immunoprecipitation which narrowed the interacting segment in ECM1 to the C-terminal tandem repeat 2 (amino acids 236-361). This peptide segment also inhibited MMP9 activity in a gelatin-based ELISA assay. We propose that ECM1-mediated reduction in MMP9 proteolytic activity may have relevance to pathogenesis of LP.

Biosensing Techniques↗

PubMed2005

Nephrotic syndrome and aberrant expression of laminin isoforms in glomerular basement membranes for an infant with Herlitz junctional epidermolysis bullosa.

Herlitz junctional epidermolysis bullosa (H-JEB) is a hereditary bullous disease caused by absent expression of laminin-5, a component of anchoring filaments within the dermal-epidermal basement membrane zone. Affected individuals usually die during the first 1 year of life. We studied an infant with H-JEB who presented with nephrotic syndrome, a previously unreported complication that may contribute to early death in this disease. DNA analysis revealed a compound heterozygote for mutations 2379delG and Q995X in the LAMB3 gene. The patient had massive albuminuria, attributable to failure of the glomerular filtration barrier, and high urinary N-acetylglucosaminidase levels, indicating renal tubular involvement. Electron-microscopic examination of the renal tissue revealed diffuse fusion of the foot processes, irregular swelling of the lamina rara interna, and disappearance of endothelial cell fenestrations. Immunohistopathologic analysis of the patient's renal tissue revealed compositional changes in laminin isoforms of the glomerular basement membrane and no detectable laminin-5 in the renal tubular basement membrane, which suggests that laminin-5 may play an important role in renal function. Our findings strongly suggest that H-JEB should be considered in the spectrum of congenital nephrotic syndromes. Combination therapy with meticulous skin care and treatment strategies established for congenital nephrotic syndromes may rescue patients with this disease.

Basement Membrane↗

PubMed2005

Extracellular matrix protein 1 interacts with the domain III of fibulin-1C and 1D variants through its central tandem repeat 2.

Extracellular matrix protein 1 (ECM1), a widely expressed glycoprotein, has been shown to harbor mutations in lipoid proteinosis (LP), an autosomal recessive disorder characterized by profound alterations in the extracellular matrix of connective tissue. The biological function of ECM1 and its role in the pathomechanisms of LP are unknown. Fibulins comprise a family of extracellular matrix components, and the prototype of this family, fibulin-1, is expressed in various connective tissues and plays a role in developmental and pathologic processes. In this study, we demonstrate that ECM1, and specifically the second tandem repeat domain which is alternatively spliced, interacts with the C-terminal segments of fibulins 1C and 1D splice variants which differ in their C-terminal domain III. The interactions were detected by yeast two-hybrid genetic system and confirmed by co-immunoprecipitations. Kinetics of the binding between ECM1 and fibulin-1D, measured by biosensor assay, revealed a K(d) of 5.71 x 10(-8) M, indicating a strong protein-protein interaction. Since distinct splice variants of ECM1 and fibulin-1 have been shown to be co-expressed in tissues affected in LP, we propose that altered ECM1/fibulin-1 interactions may play a role in the pathogenesis of this disease as well as in a number of processes involving the extracellular matrix of connective tissues.

Amino Acid Substitution↗

PubMed2005

A simplified laminin nomenclature.

A simplification of the laminin nomenclature is presented. Laminins are multidomain heterotrimers composed of alpha, beta and gamma chains. Previously, laminin trimers were numbered with Arabic numerals in the order discovered, that is laminins-1 to -5. We introduce a new identification system for a trimer using three Arabic numerals, based on the alpha, beta and gamma chain numbers. For example, the laminin with the chain composition alpha5beta1gamma1 is termed laminin-511, and not laminin-10. The current practice is also to mix two overlapping domain and module nomenclatures. Instead of the older Roman numeral nomenclature and mixed nomenclature, all modules are now called domains. Some domains are renamed or renumbered. Laminin epidermal growth factor-like (LE) domains are renumbered starting at the N-termini, to be consistent with general protein nomenclature. Domain IVb of alpha chains is named laminin 4a (L4a), domain IVa of alpha chains is named L4b, domain IV of gamma chains is named L4, and domain IV of beta chains is named laminin four (LF). The two coiled-coil domains I and II are now considered one laminin coiled-coil domain (LCC). The interruption in the coiled-coil of beta chains is named laminin beta-knob (Lbeta) domain. The chain origin of a domain is specified by the chain nomenclature, such as alpha1L4a. The abbreviation LM is suggested for laminin. Otherwise, the nomenclature remains unaltered.

Animals↗

PubMed2005

The gene family of ABC transporters--novel mutations, new phenotypes.

Members of the ABC (ATP-binding cassette) superfamily of genes encode transmembrane proteins that are involved in the transport of a variety of substrates both in and out of the cells, in addition to across intracellular membranes. Recently, mutations in two ABC-transporter genes, ABCC6 and ABCA12, have been demonstrated to underlie phenotypically different diseases affecting the skin (pseudoxanthoma elasticum and harlequin ichthyosis, respectively), attesting to the spectrum of ABC gene mutations in human diseases. These findings have a major impact on the molecular genetics of these devastating disorders in terms of DNA-based prenatal testing and pre-implantation genetic diagnosis.

ATP-Binding Cassette Transporters↗

PubMed2005

Breaking the connection: caspase 6 disconnects intermediate filament-binding domain of periplakin from its actin-binding N-terminal region.

Periplakin is a member of the plakin family of cytolinkers that connect cytoskeletal networks to each other as well as to the cell junctional complexes. Here, we demonstrate a direct molecular interaction between actin and periplakin. Furthermore, the oligomerization state of periplakin was shown to determine specificity of its binding to intermediate filaments (IF) in vitro. Both the filament association and the cell membrane localization of periplakin were confirmed in the cells overexpressing human periplakin. Double labeling of the N- and C-terminally tagged periplakin revealed unexpected lack of co-localization of periplakin ends in a confluent culture, and separation of the periplakin ends was even more pronounced in apoptotic cells. Western analysis revealed that after induction of apoptosis, periplakin becomes cleaved close to its C-terminal tail. Only the distinct cleavage products, but not the full-length periplakin, were present in the cells detached from the solid support during the apoptotic process. We show that caspase 6 cleaves periplakin at an unconventional recognition site, amino acid sequence TVAD. Thus, the separation of periplakin ends disconnects the actin-binding head-rod domain from the IF-binding C-terminal domain. We show that specific cleavage products co-exist with the full-length periplakin in cells, suggesting physiological consequences due to their altered binding specificities.

Actins↗