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‣ Missense mutations in an infectious human immunodeficiency viral genome: functional mapping of tat and identification of the rev splice acceptor.

Sadaie, M R; Rappaport, J; Benter, T; Josephs, S F; Willis, R; Wong-Staal, F
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /12/1988 Português
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Single nucleotide alterations were introduced into an infectious clone of human immunodeficiency virus type 1 to create a series of missense mutants in the tat coding region. Although mutations in a proline-rich region and a basic lysine-arginine-rich region resulted in wild-type phenotypes, five of six mutations in a cysteine-rich domain completely abolished tat activity and virus replication. One cysteine mutant retained tat activity but was negative for virus expression. Surprisingly, this mutant could not be complemented by tat, and virus expression was restored only by cotransfection with a plasmid expressing the rev gene. Another mutant with an alteration toward the C-terminal region showed significantly reduced tat activity and required complementation by a combination of tat and rev for virus replication. Further analysis revealed that a previously unrecognized splice acceptor site within this region, apparently used to generate the rev mRNA, had been altered. We provide evidence suggesting that tat and rev proteins are encoded by distinct mRNA species.

‣ Dominant missense mutations in a novel yeast protein related to mammalian phosphatidylinositol 3-kinase and VPS34 abrogate rapamycin cytotoxicity.

Cafferkey, R; Young, P R; McLaughlin, M M; Bergsma, D J; Koltin, Y; Sathe, G M; Faucette, L; Eng, W K; Johnson, R K; Livi, G P
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /10/1993 Português
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Rapamycin is a macrolide antifungal agent that exhibits potent immunosuppressive properties. In Saccharomyces cerevisiae, rapamycin sensitivity is mediated by a specific cytoplasmic receptor which is a homolog of human FKBP12 (hFKBP12). Deletion of the gene for yeast FKBP12 (RBP1) results in recessive drug resistance, and expression of hFKBP12 restores rapamycin sensitivity. These data support the idea that FKBP12 and rapamycin form a toxic complex that corrupts the function of other cellular proteins. To identify such proteins, we isolated dominant rapamycin-resistant mutants both in wild-type haploid and diploid cells and in haploid rbp1::URA3 cells engineered to express hFKBP12. Genetic analysis indicated that the dominant mutations are nonallelic to mutations in RBP1 and define two genes, designated DRR1 and DRR2 (for dominant rapamycin resistance). Mutant copies of DRR1 and DRR2 were cloned from genomic YCp50 libraries by their ability to confer drug resistance in wild-type cells. DNA sequence analysis of a mutant drr1 allele revealed a long open reading frame predicting a novel 2470-amino-acid protein with several motifs suggesting an involvement in intracellular signal transduction, including a leucine zipper near the N terminus...

‣ Chronic Infantile Neurological Cutaneous and Articular Syndrome Is Caused by Mutations in CIAS1, a Gene Highly Expressed in Polymorphonuclear Cells and Chondrocytes

Feldmann, Jérôme; Prieur, Anne-Marie; Quartier, Pierre; Berquin, Patrick; Certain, Stéphanie; Cortis, Elisabetta; Teillac-Hamel, Dominique; Fischer, Alain; Basile, Geneviève de Saint
Fonte: The American Society of Human Genetics Publicador: The American Society of Human Genetics
Tipo: Artigo de Revista Científica
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Chronic infantile neurological cutaneous and articular (CINCA) syndrome is a severe chronic inflammatory disease of early onset, characterized by cutaneous symptoms, central-nervous-system involvement, and arthropathy. In the present study, we report, in seven unrelated patients with CINCA syndrome, distinct missense mutations within the nucleotide-binding site of CIAS1, a gene encoding cryopyrin and previously shown to cause Muckle-Wells syndrome and familial cold urticaria. Because of the severe cartilage overgrowth observed in some patients with CINCA syndrome and the implications of polymorphonuclear cell infiltration in the cutaneous and neurological manifestations of this syndrome, the tissue-specific expression of CIAS1 was evaluated. A high level of expression of CIAS1 was found to be restricted to polymorphonuclear cells and chondrocytes. These findings demonstrate that CIAS1 missense mutations can result in distinct phenotypes with only a few overlapping symptoms and suggest that this gene may function as a potential inducer of apoptosis.

‣ Mutations in the Small GTP-ase Late Endosomal Protein RAB7 Cause Charcot-Marie-Tooth Type 2B Neuropathy

Verhoeven, Kristien; De Jonghe, Peter; Coen, Katrien; Verpoorten, Nathalie; Auer-Grumbach, Michaela; Kwon, Jennifer M.; FitzPatrick, David; Schmedding, Eric; De Vriendt, Els; Jacobs, An; Van Gerwen, Veerle; Wagner, Klaus; Hartung, Hans-Peter; Timmerman
Fonte: The American Society of Human Genetics Publicador: The American Society of Human Genetics
Tipo: Artigo de Revista Científica
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Charcot-Marie-Tooth type 2B (CMT2B) is clinically characterized by marked distal muscle weakness and wasting and a high frequency of foot ulcers, infections, and amputations of the toes because of recurrent infections. CMT2B maps to chromosome 3q13-q22. We refined the CMT2B locus to a 2.5-cM region and report two missense mutations (Leu129Phe and Val162Met) in the small GTP-ase late endosomal protein RAB7 which causes the CMT2B phenotype in three extended families and in three patients with a positive family history. The alignment of RAB7 orthologs shows that both missense mutations target highly conserved amino acid residues. RAB7 is ubiquitously expressed, and we found expression in sensory and motor neurons.

‣ Missense Mutations in the Homeodomain of HOXD13 Are Associated with Brachydactyly Types D and E

Johnson, David; Kan, Shih-hsin; Oldridge, Michael; Trembath, Richard C.; Roche, Philippe; Esnouf, Robert M.; Giele, Henk; Wilkie, Andrew O. M.
Fonte: The American Society of Human Genetics Publicador: The American Society of Human Genetics
Tipo: Artigo de Revista Científica
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HOXD13, the most 5′ gene of the HOXD cluster, encodes a homeodomain transcription factor with important functions in limb patterning and growth. Heterozygous mutations of human HOXD13, encoding polyalanine expansions or frameshifts, are believed to act by dominant negative or haploinsufficiency mechanisms and are predominantly associated with synpolydactyly phenotypes. Here, we describe two mutations of HOXD13 (923C→G encoding Ser308Cys and 940A→C encoding Ile314Leu) that cause missense substitutions within the homeodomain. Both are associated with distinctive limb phenotypes in which brachydactyly of specific metacarpals, metatarsals, and phalangeal bones is the most constant feature, exhibiting overlap with brachydactyly types D and E. We investigated the binding of synthetic mutant proteins to double-stranded DNA targets in vitro. No consistent differences were found for the Ser308Cys mutation compared with the wild type, but the Ile314Leu mutation (which resides at the 47th position of the homeodomain) exhibited increased affinity for a target containing the core recognition sequence 5′-TTAC-3′ but decreased affinity for a 5′-TTAT-3′ target. Molecular modeling of the Ile314Leu mutation indicates that this mixed gain and loss of affinity may be accounted for by the relative positions of methyl groups in the amino acid side chain and target base.

‣ Amerindian pyruvate carboxylase deficiency is associated with two distinct missense mutations.

Carbone, M A; MacKay, N; Ling, M; Cole, D E; Douglas, C; Rigat, B; Feigenbaum, A; Clarke, J T; Haworth, J C; Greenberg, C R; Seargeant, L; Robinson, B H
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /06/1998 Português
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We characterized the pyruvate carboxylase (PC) gene by PCR amplification, subcloning, and sequencing. The coding region has 19 exons and 18 introns spanning approximately 16 kb of genomic DNA. Screening both the cDNA and the gene of individuals with the simple A form of PC deficiency revealed an 1828G-->A missense mutation in 11 Ojibwa and 2 Cree patients and a 2229G-->T transversion mutation in 2 brothers of Micmac origin. Carrier frequency may be as high as 1/10 in some groupings. The two point mutations are located in a region of homology conserved among yeast, rat, and human PC, in the vicinity of the carboxylation domain of the enzyme. These data provide the first characterization of the human PC gene structure, the identification of common pathogenic mutations, and the demonstration of a founder effect in the Ojibwa and Cree patients.

‣ Molecular characterization of two galactosemia mutations: correlation of mutations with highly conserved domains in galactose-1-phosphate uridyl transferase.

Reichardt, J K; Packman, S; Woo, S L
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /10/1991 Português
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Galactosemia is an autosomal recessive disorder of human galactose metabolism caused by deficiency of the enzyme galactose-1-phosphate uridyl transferase (GALT). The molecular basis of this disorder is at present not well understood. We report here two missense mutations which result in low or undetectable enzymatic activity. First, we identified at nucleotide 591 a transition which substitutes glutamine 188 by arginine. The mutated glutamine is not only highly conserved in evolution (conserved also in Escherichia coli and Saccharomyces cerevisiae), but is also two amino acid residues downstream from the active site histidine-proline-histidine triad and results in about 10% of normal enzymatic activity. The arginine 188 mutation is the most common galactosemia mutation characterized to date. It accounts for one-fourth of the galactosemia alleles studied. Second, we report the substitution of arginine 333 by tryptophan, caused by a transition at nucleotide 1025. The area surrounding this missense mutation is the most highly conserved domain in the homologous enzymes from E. coli, yeast, and humans, and this mutation results in undetectable enzymatic activity, suggesting that this is a severe mutation. This second mutation appears to be rare...

‣ Homozygosity Mapping Reveals PDE6C Mutations in Patients with Early-Onset Cone Photoreceptor Disorders

Thiadens, Alberta A.H.J.; den Hollander, Anneke I.; Roosing, Susanne; Nabuurs, Sander B.; Zekveld-Vroon, Renate C.; Collin, Rob W.J.; De Baere, Elfride; Koenekoop, Robert K.; van Schooneveld, Mary J.; Strom, Tim M.; van Lith-Verhoeven, Janneke J.C.; Loter
Fonte: Elsevier Publicador: Elsevier
Tipo: Artigo de Revista Científica
Publicado em 14/08/2009 Português
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Cone photoreceptor disorders form a clinical spectrum of diseases that include progressive cone dystrophy (CD) and complete and incomplete achromatopsia (ACHM). The underlying disease mechanisms of autosomal recessive (ar)CD are largely unknown. Our aim was to identify causative genes for these disorders by genome-wide homozygosity mapping. We investigated 75 ACHM, 97 arCD, and 20 early-onset arCD probands and excluded the involvement of known genes for ACHM and arCD. Subsequently, we performed high-resolution SNP analysis and identified large homozygous regions spanning the PDE6C gene in one sibling pair with early-onset arCD and one sibling pair with incomplete ACHM. The PDE6C gene encodes the cone α subunit of cyclic guanosine monophosphate (cGMP) phosphodiesterase, which converts cGMP to 5′-GMP, and thereby plays an essential role in cone phototransduction. Sequence analysis of the coding region of PDE6C revealed homozygous missense mutations (p.R29W, p.Y323N) in both sibling pairs. Sequence analysis of 104 probands with arCD and 10 probands with ACHM revealed compound heterozygous PDE6C mutations in three complete ACHM patients from two families. One patient had a frameshift mutation and a splice defect; the other two had a splice defect and a missense variant (p.M455V). Cross-sectional retinal imaging via optical coherence tomography revealed a more pronounced absence of cone photoreceptors in patients with ACHM compared to patients with early-onset arCD. Our findings identify PDE6C as a gene for cone photoreceptor disorders and show that arCD and ACHM constitute genetically and clinically overlapping phenotypes.

‣ Familial Hemophagocytic Lymphohistiocytosis Type 5 (FHL-5) Is Caused by Mutations in Munc18-2 and Impaired Binding to Syntaxin 11

zur Stadt, Udo; Rohr, Jan; Seifert, Wenke; Koch, Florian; Grieve, Samantha; Pagel, Julia; Strauß, Julia; Kasper, Brigitte; Nürnberg, Gudrun; Becker, Christian; Maul-Pavicic, Andrea; Beutel, Karin; Janka, Gritta; Griffiths, Gillian; Ehl, Stephan; Hennies
Fonte: Elsevier Publicador: Elsevier
Tipo: Artigo de Revista Científica
Publicado em 09/10/2009 Português
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Rapid intracellular transport and secretion of cytotoxic granules through the immunological synapse requires a balanced interaction of several proteins. Disturbance of this highly regulated process underlies familial hemophagocytic lymphohistiocytosis (FHL), a genetically heterogeneous autosomal-recessive disorder characterized by a severe hyperinflammatory phenotype. Here, we have assigned FHL-5 to a 1 Mb region on chromosome 19p by using high-resolution SNP genotyping in eight unrelated FHL patients from consanguineous families. Subsequently, we found nine different mutations, either truncating or missense, in STXBP2 in twelve patients from Turkey, Saudi Arabia, and Central Europe. STXBP2 encodes syntaxin binding protein 2 (Munc18-2), involved in the regulation of vesicle transport to the plasma membrane. We have identified syntaxin 11, a SNARE protein mutated in FHL-4, as an interaction partner of STXBP2. This interaction is eliminated by the missense mutations found in our FHL-5 patients, which leads to a decreased stability of both proteins, as shown in patient lymphocytes. Activity of natural killer and cytotoxic T cells was markedly reduced or absent, as determined by CD107 degranulation. Our findings thus identify a key role for STXBP2 in lytic granule exocytosis.

‣ Mice Lacking Dystrophin or α Sarcoglycan Spontaneously Develop Embryonal Rhabdomyosarcoma with Cancer-Associated p53 Mutations and Alternatively Spliced or Mutant Mdm2 Transcripts

Fernandez, Karen; Serinagaoglu, Yelda; Hammond, Sue; Martin, Laura T.; Martin, Paul T.
Fonte: American Society for Investigative Pathology Publicador: American Society for Investigative Pathology
Tipo: Artigo de Revista Científica
Publicado em /01/2010 Português
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Altered expression of proteins in the dystrophin-associated glycoprotein complex results in muscular dystrophy and has more recently been implicated in a number of forms of cancer. Here we show that loss of either of two members of this complex, dystrophin in mdx mice or α sarcoglycan in Sgca−/− mice, results in the spontaneous development of muscle-derived embryonal rhabdomyosarcoma (RMS) after 1 year of age. Many mdx and Sgca−/− tumors showed increased expression of insulin-like growth factor 2, retinoblastoma protein, and phosphorylated Akt and decreased expression of phosphatase and tensin homolog gene, much as is found in a human RMS. Further, all mdx and Sgca−/− RMS analyzed had increased expression of p53 and murine double minute (mdm)2 protein and contained missense p53 mutations previously identified in human cancers. The mdx RMS also contained missense mutations in Mdm2 or alternatively spliced Mdm2 transcripts that lacked an exon encoding a portion of the p53-binding domain. No Pax3:Fkhr or Pax7:Fkhr translocation mRNA products were evident in any tumor. Expression of natively glycosylated α dystroglycan and α sarcoglycan was reduced in mdx RMS, whereas dystrophin expression was absent in almost all human RMS...

‣ Mutations in the Bacillus subtilis β Clamp That Separate Its Roles in DNA Replication from Mismatch Repair▿

Dupes, Nicole M.; Walsh, Brian W.; Klocko, Andrew D.; Lenhart, Justin S.; Peterson, Heather L.; Gessert, David A.; Pavlick, Cassie E.; Simmons, Lyle A.
Fonte: American Society for Microbiology (ASM) Publicador: American Society for Microbiology (ASM)
Tipo: Artigo de Revista Científica
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The β clamp is an essential replication sliding clamp required for processive DNA synthesis. The β clamp is also critical for several additional aspects of DNA metabolism, including DNA mismatch repair (MMR). The dnaN5 allele of Bacillus subtilis encodes a mutant form of β clamp containing the G73R substitution. Cells with the dnaN5 allele are temperature sensitive for growth due to a defect in DNA replication at 49°C, and they show an increase in mutation frequency caused by a partial defect in MMR at permissive temperatures. We selected for intragenic suppressors of dnaN5 that rescued viability at 49°C to determine if the DNA replication defect could be separated from the MMR defect. We isolated three intragenic suppressors of dnaN5 that restored growth at the nonpermissive temperature while maintaining an increase in mutation frequency. All three dnaN alleles encoded the G73R substitution along with one of three novel missense mutations. The missense mutations isolated were S22P, S181G, and E346K. Of these, S181G and E346K are located near the hydrophobic cleft of the β clamp, a common site occupied by proteins that bind the β clamp. Using several methods, we show that the increase in mutation frequency resulting from each dnaN allele is linked to a defect in MMR. Moreover...

‣ Compound heterozygosity for KLF1 mutations associated with remarkable increase of fetal hemoglobin and red cell protoporphyrin

Satta, Stefania; Perseu, Lucia; Moi, Paolo; Asunis, Isadora; Cabriolu, Annalisa; Maccioni, Liliana; Demartis, Franca Rosa; Manunza, Laura; Cao, Antonio; Galanello, Renzo
Fonte: Ferrata Storti Foundation Publicador: Ferrata Storti Foundation
Tipo: Artigo de Revista Científica
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The persistence of high fetal hemoglobin level in adults may ameliorate the clinical phenotype of beta-thalassemia and sickle cell anemia. Several genetic variants responsible for hereditary persistence of fetal hemoglobin, linked and not linked to the beta globin gene cluster, have been identified in patients and in normal individuals. Monoallelic loss of KLF1, a gene with a key role in erythropoiesis, has been recently reported to be responsible for persistence of high levels of fetal hemoglobin. In a Sardinian family, high levels of HbF (22.1–30.9%) were present only in compound heterozygotes for the S270X nonsense and K332Q missense mutations, while the isolated S270X nonsense (haploinsufficiency) or K332Q missense mutation were associated with normal HbF levels (<1.5%). Functionally, the K332Q Klf1 mutation impairs binding to the BCl11A gene and activation of the γ- and β-globin promoters. Moreover, we report for the first time the association of KLF1 mutations with very high levels of zinc protoporphyrin.

‣ Mutations in Frizzled 6 Cause Isolated Autosomal-Recessive Nail Dysplasia

Fröjmark, Anne-Sophie; Schuster, Jens; Sobol, Maria; Entesarian, Miriam; Kilander, Michaela B.C.; Gabrikova, Dana; Nawaz, Sadia; Baig, Shahid M.; Schulte, Gunnar; Klar, Joakim; Dahl, Niklas
Fonte: Elsevier Publicador: Elsevier
Tipo: Artigo de Revista Científica
Publicado em 10/06/2011 Português
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Inherited and isolated nail malformations are rare and heterogeneous conditions. We identified two consanguineous pedigrees in which some family members were affected by isolated nail dysplasia that suggested an autosomal-recessive inheritance pattern and was characterized by claw-shaped nails, onychauxis, and onycholysis. Genome-wide SNP array analysis of affected individuals from both families showed an overlapping and homozygous region of 800 kb on the long arm of chromosome 8. The candidate region spans eight genes, and DNA sequence analysis revealed homozygous nonsense and missense mutations in FZD6, the gene encoding Frizzled 6. FZD6 belongs to a family of highly conserved membrane-bound WNT receptors involved in developmental processes and differentiation through several signaling pathways. We expressed the FZD6 missense mutation and observed a quantitative shift in subcellular distribution from the plasma membrane to the lysosomes, where the receptor is inaccessible for signaling and presumably degraded. Analysis of human fibroblasts homozygous for the nonsense mutation showed an aberrant response to both WNT-3A and WNT-5A stimulation; this response was consistent with an effect on both canonical and noncanonical WNT-FZD signaling. A detailed analysis of the Fzd6−/− mice...

‣ Mutations in C8orf37, Encoding a Ciliary Protein, are Associated with Autosomal-Recessive Retinal Dystrophies with Early Macular Involvement

Estrada-Cuzcano, Alejandro; Neveling, Kornelia; Kohl, Susanne; Banin, Eyal; Rotenstreich, Ygal; Sharon, Dror; Falik-Zaccai, Tzipora C.; Hipp, Stephanie; Roepman, Ronald; Wissinger, Bernd; Letteboer, Stef J.F.; Mans, Dorus A.; Blokland, Ellen A.W.; Kwi
Fonte: Elsevier Publicador: Elsevier
Tipo: Artigo de Revista Científica
Publicado em 13/01/2012 Português
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Cone-rod dystrophy (CRD) and retinitis pigmentosa (RP) are clinically and genetically overlapping heterogeneous retinal dystrophies. By using homozygosity mapping in an individual with autosomal-recessive (ar) RP from a consanguineous family, we identified three sizeable homozygous regions, together encompassing 46 Mb. Next-generation sequencing of all exons, flanking intron sequences, microRNAs, and other highly conserved genomic elements in these three regions revealed a homozygous nonsense mutation (c.497T>A [p.Leu166∗]) in C8orf37, located on chromosome 8q22.1. This mutation was not present in 150 ethnically matched control individuals, single-nucleotide polymorphism databases, or the 1000 Genomes database. Immunohistochemical studies revealed C8orf37 localization at the base of the primary cilium of human retinal pigment epithelium cells and at the base of connecting cilia of mouse photoreceptors. C8orf37 sequence analysis of individuals who had retinal dystrophy and carried conspicuously large homozygous regions encompassing C8orf37 revealed a homozygous splice-site mutation (c.156−2A>G) in two siblings of a consanguineous family and homozygous missense mutations (c.529C>T [p.Arg177Trp]; c.545A>G [p.Gln182Arg]) in siblings of two other consanguineous families. The missense mutations affect highly conserved amino acids...

‣ Exome Sequencing Reveals Mutations in TRPV3 as a Cause of Olmsted Syndrome

Lin, Zhimiao; Chen, Quan; Lee, Mingyang; Cao, Xu; Zhang, Jie; Ma, Donglai; Chen, Long; Hu, Xiaoping; Wang, Huijun; Wang, Xiaowen; Zhang, Peng; Liu, Xuanzhu; Guan, Liping; Tang, Yiquan; Yang, Haizhen; Tu, Ping; Bu, Dingfang; Zhu, Xuejun; Wang, KeWei; Li, R
Fonte: Elsevier Publicador: Elsevier
Tipo: Artigo de Revista Científica
Publicado em 09/03/2012 Português
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Olmsted syndrome (OS) is a rare congenital disorder characterized by palmoplantar and periorificial keratoderma, alopecia in most cases, and severe itching. The genetic basis for OS remained unidentified. Using whole-exome sequencing of case-parents trios, we have identified a de novo missense mutation in TRPV3 that produces p.Gly573Ser in an individual with OS. Nucleotide sequencing of five additional affected individuals also revealed missense mutations in TRPV3 (which produced p.Gly573Ser in three cases and p.Gly573Cys and p.Trp692Gly in one case each). Encoding a transient receptor potential vanilloid-3 cation channel, TRPV3 is primarily expressed in the skin, hair follicles, brain, and spinal cord. In transfected HEK293 cells expressing TRPV3 mutants, much larger inward currents were recorded, probably because of the constitutive opening of the mutants. These gain-of-function mutations might lead to elevated apoptosis of keratinocytes and consequent skin hyperkeratosis in the affected individuals. Our findings suggest that TRPV3 plays essential roles in skin keratinization, hair growth, and possibly itching sensation in humans and selectively targeting TRPV3 could provide therapeutic potential for keratinization or itching-related skin disorders.

‣ Specific Missense Alleles of the Arabidopsis Jasmonic Acid Co-Receptor COI1 Regulate Innate Immune Receptor Accumulation and Function

He, Yijian; Chung, Eui-Hwan; Hubert, David A.; Tornero, Pablo; Dangl, Jeffery L.
Fonte: Public Library of Science Publicador: Public Library of Science
Tipo: Artigo de Revista Científica
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Plants utilize proteins containing nucleotide binding site (NB) and leucine-rich repeat (LRR) domains as intracellular innate immune receptors to recognize pathogens and initiate defense responses. Since mis-activation of defense responses can lead to tissue damage and even developmental arrest, proper regulation of NB–LRR protein signaling is critical. RAR1, SGT1, and HSP90 act as regulatory chaperones of pre-activation NB–LRR steady-state proteins. We extended our analysis of mutants derived from a rar1 suppressor screen and present two allelic rar1 suppressor (rsp) mutations of Arabidopsis COI1. Like all other coi1 mutations, coi1rsp missense mutations impair Jasmonic Acid (JA) signaling resulting in JA–insensitivity. However, unlike previously identified coi1 alleles, both coi1rsp alleles lack a male sterile phenotype. The coi1rsp mutants express two sets of disease resistance phenotypes. The first, also observed in coi1-1 null allele, includes enhanced basal defense against the virulent bacterial pathogen Pto DC3000 and enhanced effector-triggered immunity (ETI) mediated by the NB–LRR RPM1 protein in both rar1 and wild-type backgrounds. These enhanced disease resistance phenotypes depend on the JA signaling function of COI1. Additionally...

‣ Mutations in WNT1 Cause Different Forms of Bone Fragility

Keupp, Katharina; Beleggia, Filippo; Kayserili, Hülya; Barnes, Aileen M.; Steiner, Magdalena; Semler, Oliver; Fischer, Björn; Yigit, Gökhan; Janda, Claudia Y.; Becker, Jutta; Breer, Stefan; Altunoglu, Umut; Grünhagen, Johannes; Krawitz, Peter; Hecht
Fonte: Elsevier Publicador: Elsevier
Tipo: Artigo de Revista Científica
Publicado em 04/04/2013 Português
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We report that hypofunctional alleles of WNT1 cause autosomal-recessive osteogenesis imperfecta, a congenital disorder characterized by reduced bone mass and recurrent fractures. In consanguineous families, we identified five homozygous mutations in WNT1: one frameshift mutation, two missense mutations, one splice-site mutation, and one nonsense mutation. In addition, in a family affected by dominantly inherited early-onset osteoporosis, a heterozygous WNT1 missense mutation was identified in affected individuals. Initial functional analysis revealed that altered WNT1 proteins fail to activate canonical LRP5-mediated WNT-regulated β-catenin signaling. Furthermore, osteoblasts cultured in vitro showed enhanced Wnt1 expression with advancing differentiation, indicating a role of WNT1 in osteoblast function and bone development. Our finding that homozygous and heterozygous variants in WNT1 predispose to low-bone-mass phenotypes might advance the development of more effective therapeutic strategies for congenital forms of bone fragility, as well as for common forms of age-related osteoporosis.

‣ A Novel Missense (M206K) STAT3 Mutation in Diffuse Large B Cell Lymphoma Deregulates STAT3 Signaling

Hu, Guangzhen; Witzig, Thomas E.; Gupta, Mamta
Fonte: Public Library of Science Publicador: Public Library of Science
Tipo: Artigo de Revista Científica
Publicado em 04/07/2013 Português
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Persistent STAT3 activation has been found in activated B-cell like diffuse large B cell tumors (DLBCL). To investigate whether genetic mutations play a role in aberrant STAT3 signaling in DLBCL, we bi-directionally sequenced all 24 exons of the STAT3 gene in DLBCL tumors (n = 40). We identified 2 novel point mutations in 2 separate (2/40; 5%) patients at exon 7 and 24. Point mutation 2552G>A was a silent mutation in the stop codon. Another heterozygous mutation 857T>A encoded a methionine substitution by lysine at codon 206 (M206K) in the coiled-coil domain of STAT3. We performed site directed mutagenesis to mutate wild type (WT) STAT3α and STAT3β at codon 206 and constructed stable cell lines by lentiviral transfection of STAT3αWT, STAT3αM206K, STAT3βWT and STAT3βM206K plasmids. The mutation was found to increase STAT3 phosphorylation in STAT3α mutant cell lines with no effect on the STAT3β mutant cell line. Transcriptional activation was also increased in the STAT3α mutant cells compared with STAT3α WT cells as detected by a luciferase reporter assay. Moreover, STAT3αM206K mutant cells were resistant to JAK2 pathway inhibition compared to STAT3α WT cells. These results indicate that missense mutations in STAT3 increase signaling through the JAK/STAT pathway. JAK2 inhibitors may be useful in the patient with this STAT3 mutation as well as those with pathway activation by other mechanisms.

‣ An RNA-seq Protocol to Identify mRNA Expression Changes in Mouse Diaphyseal Bone: Applications in Mice with Bone Property Altering Lrp5 Mutations

Ayturk, Ugur M.; Jacobsen, Christina M.; Christodoulou, Danos C.; Gorham, Joshua; Seidman, Jonathan G.; Seidman, Christine E.; Robling, Alexander G.; Warman, Matthew L.
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /10/2013 Português
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Loss-of-function and certain missense mutations in the Wnt co-receptor LRP5 significantly decrease or increase bone mass, respectively. These human skeletal phenotypes have been recapitulated in mice harboring Lrp5 knockout and knockin mutations. We hypothesized that measuring mRNA expression in diaphyseal bone from mice with Lrp5 wild-type (Lrp5+/+), knockout (Lrp5−/−), and high bone mass (HBM)-causing (Lrp5p.A214V/+) alleles could identify genes and pathways that regulate or are regulated by LRP5 activity. We performed RNA-seq on pairs of tibial diaphyseal bones from four 16-week-old mice with each of the aforementioned genotypes. We then evaluated different methods for controlling for contaminating non-skeletal tissue (i.e., blood, bone marrow, and skeletal muscle) in our data. These methods included pre-digestion of diaphyseal bone with collagenase and separate transcriptional profiling of blood, skeletal muscle and bone marrow. We found that collagenase digestion reduced contamination, but also altered gene expression in the remaining cells. In contrast, in silico filtering of the diaphyseal bone RNA-seq data for highly expressed blood, skeletal muscle, and bone marrow transcripts significantly increased the correlation between RNA-seq data from an animal’s right and left tibiae and from animals with the same Lrp5 genotype. We conclude that reliable and reproducible RNA-seq data can be obtained from mouse diaphyseal bone and that lack of LRP5 has a more pronounced effect on gene expression than the HBM-causing LRP5 missense mutation. We identified 84 differentially expressed protein-coding transcripts between LRP5 “sufficient” (i.e....

‣ NR2F1 Mutations Cause Optic Atrophy with Intellectual Disability

Bosch, Daniëlle G.M.; Boonstra, F. Nienke; Gonzaga-Jauregui, Claudia; Xu, Mafei; de Ligt, Joep; Jhangiani, Shalini; Wiszniewski, Wojciech; Muzny, Donna M.; Yntema, Helger G.; Pfundt, Rolph; Vissers, Lisenka E.L.M.; Spruijt, Liesbeth; Blokland, Elle
Fonte: Elsevier Publicador: Elsevier
Tipo: Artigo de Revista Científica
Publicado em 06/02/2014 Português
Relevância na Pesquisa
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Optic nerve atrophy and hypoplasia can be primary disorders or can result from trans-synaptic degeneration arising from cerebral visual impairment (CVI). Here we report six individuals with CVI and/or optic nerve abnormalities, born after an uneventful pregnancy and delivery, who have either de novo heterozygous missense mutations in NR2F1, also known as COUP-TFI, or deletions encompassing NR2F1. All affected individuals show mild to moderate intellectual impairment. NR2F1 encodes a nuclear receptor protein that regulates transcription. A reporter assay showed that missense mutations in the zinc-finger DNA-binding domain and the putative ligand-binding domain decrease NR2F1 transcriptional activity. These findings indicate that NR2F1 plays an important role in the neurodevelopment of the visual system and that its disruption can lead to optic atrophy with intellectual disability.