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PubMed2025

A small cationic probe for accurate, punctate discovery of RNA tertiary structure.

RNA molecules fold into intricate three-dimensional tertiary structures that are central to their biological functions. Yet reliably discovering new motifs that form true tertiary interactions remains a major challenge. Here we show that RNA tertiary folding occasionally generates electronegative motifs that react selectively with the small, positively-charged probe trimethyloxonium (TMO). Sites with enhanced reactivity to TMO, compared with the neutral reagent dimethyl sulfate (DMS), are indicative of tertiary structure and define T-sites. These positions share a structural signature in which a reactive nucleobase is adjacent to non-bridging phosphate oxygens, creating localized regions of negative charge. T-sites consistently map to the cores of higher-order structural interactions and functional centers across diverse RNAs, including distinct states in conformational ensembles. In the 10,723-nt dengue virus genome, three strong T-sites were detected, each within a complex structure required for viral replication. Cation-based covalent chemistry enables high-confidence discovery and analysis of functional RNA tertiary motifs across long and complex RNAs, opening new opportunities for transcriptome-wide structural analysis.

RNA electrostatics↗

PubMed2002

Functional analysis of an Arabidopsis T-DNA "knockout" of the high-affinity NH4(+) transporter AtAMT1;1.

NH(4)(+) acquisition by plant roots is thought to involve members of the NH(4)(+) transporter family (AMT) found in plants, yeast, bacteria, and mammals. In Arabidopsis, there are six AMT genes of which AtAMT1;1 demonstrates the highest affinity for NH(4)(+). Ammonium influx into roots and AtAMT1;1 mRNA expression levels are highly correlated diurnally and when plant nitrogen (N) status is varied. To further investigate the involvement of AtAMT1;1 in high-affinity NH(4)(+) influx, we identified a homozygous T-DNA mutant with disrupted AtAMT1;1 activity. Contrary to expectation, high-affinity (13)NH(4)(+) influx in the amt1;1:T-DNA mutant was similar to the wild type when grown with adequate N. Removal of N to increase AtAMT1;1 expression decreased high-affinity (13)NH(4)(+) influx in the mutant by 30% compared with wild-type plants, whereas low-affinity (13)NH(4)(+) influx (250 microM-10 mM NH(4)(+)) exceeded that of wild-type plants. In these N-deprived plants, mRNA copy numbers of root AtAMT1;3 and AtAMT2;1 mRNA were significantly more increased in the mutant than in wild-type plants. Under most growth conditions, amt1;1:T-DNA plants were indistinguishable from the wild type, however, leaf morphology was altered. However, when grown with NH(4)(+) and sucrose, the mutant grew poorly and died. Our results are the first in planta evidence that AtAMT1;1 is a root NH(4)(+) transporter and that redundancies within the AMT family may allow compensation for the loss of AtAMT1;1.

Ammonium Sulfate↗

PubMed2006

Generation of a flanking sequence-tag database for activation-tagging lines in japonica rice.

We have generated 47,932 T-DNA tag lines in japonica rice using activation-tagging vectors that contain tetramerized 35S enhancer sequences. To facilitate use of those lines, we isolated the genomic sequences flanking the inserted T-DNA via inverse polymerase chain reaction. For most of the lines, we performed four sets of amplifications using two different restriction enzymes toward both directions. In analyzing 41,234 lines, we obtained 27,621 flanking sequence tags (FSTs), among which 12,505 were integrated into genic regions and 15,116 into intergenic regions. Mapping of the FSTs on chromosomes revealed that T-DNA integration frequency was generally proportional to chromosome size. However, T-DNA insertions were non-uniformly distributed on each chromosome: higher at the distal ends and lower in regions close to the centromeres. In addition, several regions showed extreme peaks and valleys of insertion frequency, suggesting hot and cold spots for T-DNA integration. The density of insertion events was somewhat correlated with expressed, rather than predicted, gene density along each chromosome. Analyses of expression patterns near the inserted enhancer showed that at least half the test lines displayed greater expression of the tagged genes. Whereas in most of the increased lines expression patterns after activation were similar to those in the wild type, thereby maintaining the endogenous patterns, the remaining lines showed changes in expression in the activation tagged lines. In this case, ectopic expression was most frequently observed in mature leaves. Currently, the database can be searched with the gene locus number or location on the chromosome at http://www.postech.ac.kr/life/pfg/risd. On request, seeds of the T(1) or T(2) plants will be provided to the scientific community.

Chromosome Mapping↗

PubMed2006

Ultrastructural characteristics of tau filaments in tauopathies: immuno-electron microscopic demonstration of tau filaments in tauopathies.

The microtubule-associated protein tau aggregates into filaments in the form of neurofibrillary tangles, neuropil threads and argyrophilic grains in neurons, in the form of variable astrocytic tangles in astrocytes and in the form of coiled bodies and argyrophilic threads in oligodendrocytes. These tau filaments may be classified into two types, straight filaments or tubules with 9-18 nm diameters and "twisted ribbons" composed of two parallel aligned components. In the same disease, the fine structure of tau filaments in glial cells roughly resembles that in neurons. In sporadic tauopathies, individual tau filaments show characteristic sizes, shapes and arrangements, and therefore contribute to neuropathologic differential diagnosis. In frontotemporal dementias caused by tau gene mutations, variable filamentous profiles were observed in association with mutation sites and insoluble tau isoforms, including straight filaments or tubules, paired helical filament-like filaments, and twisted ribbons. Pre-embedding immunoelectron microscopic studies were carried out using anti-3-repeat tau and anti-4-repeat tau specific antibodies, RD3 and RD4. Straight tubules in neuronal and astrocytic Pick bodies were immunolabeled by the anti-3-repeat tau antibody. The anti-4-repeat tau antibody recognized abnormal tubules comprising neurofibrillary tangles, coiled bodies and argyrophilic threads in progressive supranuclear palsy (PSP) and corticobasal degeneration. In the pre-embedding immunoelectron microscopic study using the phosphorylated tau AT8 antibody, tuft-shaped astrocytes of PSP were found to be composed of bundles of abnormal tubules in processes and perikarya of protoplasmic astrocytes. In this study, the 3-repeat tau or 4-repeat tau epitope was detected in situ at the ultrastructural level in abnormal tubules in representative pathological lesions in Pick's disease, PSP and corticobasal degeneration.

Astrocytes↗

PubMed2005

Proposed function of the accumulation of plasma membrane-type Ca2+-ATPase mRNA in resting cysts of the ciliate Sterkiella histriomuscorum.

From an mRNA differential-display analysis of the encystment-excystment cycle of the ciliate Sterkiella histriomuscorum, we have isolated an expressed sequence tag encoding a plasma membrane-type Ca2+-ATPase (PMCA). PMCAs are located either in the plasma membranes or in the membranes of intracellular organelles, and their function is to pump calcium either out of the cell or into the intracellular calcium stores, respectively. The S. histriomuscorum macronuclear PMCA gene (ShPMCA) and its corresponding cDNA were cloned; it is the first member of the Ca2+-ATPase family identified in Sterkiella. The predicted protein of 1,065 amino acids exhibits 37% identity with PMCAs of diverse organisms. A phylogenetic analysis showed its relatedness to homologs of two alveolates: the ciliate Paramecium tetraurelia and the apicomplexan Toxoplasma gondii. Overexpression of the protein ShPMCA failed to rescue the wild-type phenotype of three Ca2+-ATPase-defective mutant strains of Saccharomyces cerevisiae; this failure contrasts with the reported ability of the PMCAs of parasites to complement defects in yeast. ShPMCA mRNA is markedly accumulated during encystment and in resting cysts, suggesting a function during excystment. To address the possibility of a signaling role for calcium at excystment, the capacity of calcium to induce excystment was examined.

Animals↗

PubMed2005

Generation and molecular characterization of head and neck squamous cell lines of fanconi anemia patients.

Patients with Fanconi anemia (FA) are prone to develop malignancies at an early age. Besides hematologic malignancies, squamous cell carcinomas in the anogenital region and head and neck are also frequently found in these patients. The aim of this study was to generate a panel of head and neck squamous cell carcinoma (HNSCC) cell lines and xenografts of FA HNSCC, and to characterize these cell lines in comparison with a panel of seven cell lines from patients with sporadic HNSCC. Analyses have been done on sensitivity to DNA cross-linking agents, loss of heterozygosity profile, TP53 mutations, TP53 polymorphisms and the presence of human papillomavirus. Four FA HNSCC cell lines were established. Sensitivity to DNA cross-linking agents (cisplatin) in the FA HNSCC cell lines was on average 10 times higher as compared with the sporadic HNSCC cell lines. Human papillomavirus was not detected in any of the FA or sporadic cell lines. No differences were found in loss of heterozygosity pattern, TP53 mutation frequency and TP53 polymorphism between FA and sporadic HNSCC cell lines. This is the first report on the generation of squamous cell lines of FA patients. The FA HNSCC cell lines we have generated may be utilized for future studies and might aid in the development of new preventive therapies for FA patients. The genetic characteristics of these cell lines suggest that FA HNSCC are not very different from sporadic HNSCC, except for the sensitivity to cisplatin which is consistent with the known cellular FA phenotype.

Adult↗

PubMed2005

Prevalence, clinical profile, and prognosis of NPM mutations in AML with normal karyotype.

Mutation of the nucleophosmin (NPM) gene has been reported as the most frequent mutation in acute myeloid leukemia (AML), especially in the presence of a normal karyotype. In this subgroup of intermediate-risk AML, the identification of other gene mutations (eg, FLT3, CCAAT/enhancer-binding protein-alpha [CEBPA]) has helped to refine the prognosis. This study explored the prevalence and the prognostic impact of NPM mutations in a cohort of 106 patients with normal-karyotype AML. NPM exon 12 mutations were detected by polymerase chain reaction (PCR) and fragment analysis for the insertion/deletion globally resulting in a 4-bp insertion. NPM mutations were detected in 47% of patients and were associated with a high white blood cell count, involvement of the monocytic lineage (M4/M5), and a decreased prevalence of CEBPA mutations. Complete remission rate and long-term outcome did not differ between NPM-mutated and -nonmutated patients. Prospective studies are needed to confirm the definitive place of NPM mutation detection to predict AML response to therapy.

Adolescent↗

PubMed2001

Mechanisms of MHC class I-restricted antigen presentation.

The vertebrate immune system monitors whether an organism is invaded by pathogens. Therefore, each cell has to prove itself as healthy. This is achieved by presenting fragments of intracellular protein degradation products on the surface, i.e., each cell displays peptides on specialised proteins known as major histocompatibility complex (MHC) class I proteins. A displayed peptide has to pass certain constraints before its presentation: It has to be excised out of a protein, translocated into the endoplasmic reticulum (ER) and fit into the binding groove of a MHC molecule. In theory, alteration of the cellular protein profile by mutation or infection should force pathogen-specific T-cells to take action via recognition of foreign peptide bound to MHC class I molecules on the cell surface. Unfortunately, pathogens and tumours have evolved many ways to affect antigen presentation and to escape from immune response. Understanding the exact mechanisms of antigen presentation, i.e., protein cleavage and peptide binding by MHC molecules, would allow their manipulation by drugs and lead to the re-establishment of the correct antigen presentation pathway. This review will summarise current knowledge of the mechanisms of antigen presentation and discuss putative targets for therapeutic treatment as well as for vaccination strategies.

Journal Article↗

PubMed2006

Mechanisms inactivating the gene for E-cadherin in sporadic gastric carcinomas.

AIM: To study the role of CDH1/E-cadherin (E-cad) gene alteration profiles including mutation, loss of heterozygosity (LOH), promoter polymorphism and hypermethylation in mechanisms of CDH1 inactivation in gastric carcinoma (GC). METHODS: Specimens were collected surgically from 70 patients with GC. Allelotyping PCR and detection of LOH, denaturing high pressure liquid chromatography and DNA sequencing, restriction fragment length polymorphism analysis, methylation specific PCR, and immunohistochemical staining were used. RESULTS: Promoter polymorphism was not a major mechanism of E-cad inactivation. Only one truncating mutation was found in a diffuse type tumor (3%). Both LOH and promoter hypermethylation were major mechanisms of E-cad inactivation, but interestingly, there was a negative association between the fraction of allelic loss (LOH) in tumors and hypermethylation of CDH1. Therefore LOH and hypermethylation were two different tumorigenic pathways involved in GC. CONCLUSION: Given the findings that somatic mutation was extremely low and the relationship between LOH and hypermethylation was inverse, any two combinations of these three factors cannot fulfill the classical two-hit hypothesis of CDH1 inactivation. Thus, other mechanisms operating at the transcriptional level or at the post-translational level might be required to induce E-cadherin inactivation.

Adult↗

PubMed2000

Thyroid carcinomas with mixed follicular and C-cell differentiation patterns.

Divergent endocrine-neuroendocrine differentiation in thyroid carcinoma occurs in mixed medullary-follicular carcinomas (MMFC). Less than 40 cases of MMFC have been reported having highly heterogeneous patterns of growth. Classical medullary carcinoma areas may be intermingled with follicles or papillae or even oxyphilic and solid areas. Calcitonin and thyroglobulin are expressed in different cell populations. Presence of the latter suggests a potential usefulness of radioiodine treatment. The clinical behavior of MMFC does not differ from that of ordinary medullary carcinoma. The histogenesis of MMFC is controversial. The genetic analysis of the 2 neoplastic components showed that they are not derived from a common precursor, but rather display remarkable differences in the genetic profile (RET mutations and allelic losses). In addition, in some cases the follicular component was found to be oligo/polyclonal and therefore possibly hyperplastic rather than neoplastic. The follicular cells may have grown into the medullary carcinoma, after acquiring some molecular defect, being "hostage" of the true neoplastic (medullary) component.

Adenocarcinoma, Follicular↗

PubMed2002

Recombinase-directed plant transformation for the post-genomic era.

Plant genomics promises to accelerate genetic discoveries for plant improvements. Machine-driven technologies are ushering in gene structural and expressional data at an unprecedented rate. Potential bottlenecks in this crop improvement process are steps involving plant transformation. With few exceptions, genetic transformation is an obligatory final step by which useful traits are engineered into plants. In addition, transgenesis is most often needed to confirm gene function, after deductions made through comparative genomics, expression profiles, and mutation analysis. This article reviews the use of recombinase systems to deliver DNA more efficiently into the plant genome.

Base Sequence↗

PubMed2002

[From cytogenetics to cytogenomics of bladder cancers].

Bladder cancers are classified as: transitional cell carcinoma (TCC), the most frequent in Europe/USA, squamous cell carcinoma (SCC), more frequent in the Middle East and in Africa, adenocarcinoma and small cell carcinoma, rare. TCC exhibit pseudo diploid karyotypes with only a few anomalies in early stages, evolving towards pseudo-tetraploides complexes karyotypes. Partial or complete monosomy 9 (-9) is an early event, found in half cases. Deletion (11p) or -11 is found in 20-50% of cases, more often in high grade and invasive tumours. Del(13q) is found in 25% of cases and correlated with high grade/stage; tumours with Rb alterations are invasives. Del(17p) is a late event, found in 40% of cases; P53 alterations are correlated with grade and stage, tumour progression, and a worse prognosis. Del(1p), i(5q), +7, and many other rearrangements - more often deletions than duplications - are frequently found. These losses of heterozygocity point to a multistep complex process involving tumor suppressor genes. In SCC, monosomy 9 is also an early event, even more frequent than in TCC; homozygous deletion of P16 is frequent. Trisomy 7 seems to be more frequent than in TCC. Chromosome 17 is often implicated, especially in high grades/stages; the profile of mutations of P53 is different from what is found in TCC. Allelic losses of 3p, 8p, 9p, 9q, 17p are frequent. The karyotype is more complex in advanced grades/stages, as in TCC.

Carcinoma, Small Cell↗

PubMed2026

Lung Squamous Cell Carcinoma Harbouring a Novel PAX8::PPARγ Fusion and a FGFR2 Exon 7 Missense Mutation.

Comprehensive molecular profiling is now routinely performed in newly diagnosed non-small cell lung carcinomas (NSCLCs) to identify actionable genomic alterations. Although numerous molecular abnormalities have been described in lung carcinomas, rare and unexpected gene fusions may create significant diagnostic challenges, particularly when they are characteristically associated with tumours of different lineages. To our knowledge, this is the first reported case of a primary lung squamous cell carcinoma harbouring an in-frame PAX8::PPARγ fusion with a concurrent FGFR2 exon 7 missense mutation (p.W290C). An 80-year-old man with a smoking history exceeding 50 years presented with a rapidly enlarging PET-avid right upper lobe pulmonary mass. Bronchial brushing cytology demonstrated a hypercellular malignant neoplasm composed of pleomorphic squamoid cells with hyperchromatic nuclei, dense cytoplasm and extensive necrosis. Cell block material showed squamous morphology and diffuse p40 positivity, supporting squamous differentiation. Reflex next-generation sequencing identified an FGFR2 exon 7 missense mutation (p.W290C; c.870G>C) and targeted RNA fusion analysis demonstrated an in-frame PAX8::PPARγ fusion resulting from a t(2;3)(q13;p25.2) translocation. Because PAX8::PPARγ rearrangements are strongly associated with follicular thyroid neoplasms, extensive clinicoradiologic and immunohistochemical correlation was performed to exclude metastatic thyroid carcinoma. Imaging studies showed no thyroid lesion or residual thyroid tissue, and tumour cells were negative for thyroglobulin, TTF-1 and PAX8. Correlation of the clinical history, radiologic findings, cytomorphology, immunophenotype and molecular profile supported the diagnosis of primary lung squamous cell carcinoma. This case expands the molecular spectrum of lung squamous cell carcinoma and highlights the importance of integrated cytopathologic, immunohistochemical, molecular and radiologic evaluation when unexpected gene fusions are identified in cytology specimens.

FGFR2 exon 7 missense mutation↗

PubMed2006

Mutation and genomic deletion status of ataxia telangiectasia mutated (ATM) and p53 confer specific gene expression profiles in mantle cell lymphoma.

Although mantle cell lymphoma (MCL) frequently harbors inactivated ataxia telangiectasia mutated (ATM) and p53 alleles, little is known about the molecular phenotypes caused by these genetic changes. We identified point mutations and genomic deletions in these genes in a series of cyclin D1-positive MCL cases and correlated genotype with gene expression profiles and overall survival. Mutated and/or deleted ATM and p53 alleles were found in 56% (40/72) and 26% (21/82) of the cases examined, respectively. Although MCL patients with inactive p53 alleles showed a significant reduction in median overall survival, aberrant ATM status did not predict for survival. Nevertheless, specific gene expression signatures indicative of the mutation and genomic deletion status of each gene were identified that were different from wild-type cases. These signatures were comprised of a select group of genes related to apoptosis, stress responses, and cell cycle regulation that are relevant to ATM or p53 function. Importantly, we found the molecular signatures are different between cases with mutations and deletions, because the latter are characterized by loss of genes colocalized in the same chromosome region of ATM or p53. This information on molecular phenotypes may provide new areas of investigation for ATM function or may be exploited by designing specific therapies for MCL cases with p53 aberrations.

Apoptosis↗

PubMed2005

CFTR DeltaF508 mutation has minimal effect on the gene expression profile of differentiated human airway epithelia.

Cystic fibrosis (CF) is caused by mutations in the cystic fibrosis transmembrane conductance regulator (CFTR), an epithelial chloride channel regulated by phosphorylation. Most of the disease-associated morbidity is the consequence of chronic lung infection with progressive tissue destruction. As an approach to investigate the cellular effects of CFTR mutations, we used large-scale microarray hybridization to contrast the gene expression profiles of well-differentiated primary cultures of human CF and non-CF airway epithelia grown under resting culture conditions. We surveyed the expression profiles for 10 non-CF and 10 DeltaF508 homozygote samples. Of the 22,283 genes represented on the Affymetrix U133A GeneChip, we found evidence of significant changes in expression in 24 genes by two-sample t-test (P < 0.00001). A second, three-filter method of comparative analysis found no significant differences between the groups. The levels of CFTR mRNA were comparable in both groups. There were no significant differences in the gene expression patterns between male and female CF specimens. There were 18 genes with significant increases and 6 genes with decreases in CF relative to non-CF samples. Although the function of many of the differentially expressed genes is unknown, one transcript that was elevated in CF, the KCl cotransporter (KCC4), is a candidate for further study. Overall, the results indicate that CFTR dysfunction has little direct impact on airway epithelial gene expression in samples grown under these conditions.

Cell Differentiation↗

PubMed1999

Development of the child's voice: premutation, mutation.

Voice range profile (VRP) measurement was used to evaluate the vocal capabilities of 180 children aged between 4 and 12 years without voice pathology. There were 10 boys and 10 girls in each age group. Using an automatic VRP measurement system, F0 and SPL dB (lin) were determined and displayed two-dimensionally in real time. The speaking voice, the shouting voice and the singing voice were investigated. The results show that vocal capabilities grow with advancing age, but not continuously. The lowering of the habitual pitch of the speaking voice as well as of the entire speaking pitch range occurs for girls between the ages of 7 and 8, for boys between 8 and 9. A temporary restriction of the minimum vocal intensity of the speaking voice (the ability to speak softly) as well as of the singing voice occurs for girls and for boys at the age of 7-8. A decrease of the maximum speech intensity is found for girls at the age of between 7 and 8, for boys between 8 and 9. A lowering of the pitch as well as of the intensity of the shouting voice occurs for both sexes from the age of 10. In contrast to earlier general opinion we note for girls a stage of premutation (between the age of 7 and 8) with essentially the same changes seen among boys, but 1 year earlier. The beginning of the mutation can be fixed at the age of 10-11 years.

Child↗

PubMed2006

Genotyping of five chinese patients with 17alpha-hydroxylase deficiency diagnosed through high-performance liquid chromatography serum adrenal profile: identification of two novel CYP17 mutations.

CONTEXT: 17alpha-Hydroxylase deficiency is a rare form of congenital adrenal hyperplasia caused by CYP17 gene mutations. OBJECTIVE: Five Chinese patients with 17alpha-hydroxylase deficiency were genotyped. PATIENTS: The five patients derived from four families living in Shandong Province, China. The diagnosis of 17alpha-hydroxylase deficiency was initially established through HPLC serum adrenal profiles in Qilu Hospital, China, from 1983-1993. RESULTS: Three CYP17 gene mutations were identified from these patients. Among them, V311fs and Y329fs are two novel frame-shifting mutations. V311fs is an 8-bp nucleotide (TTAAATGG) deletion in exon 5. Y329fs is a deletion-insertion combined mutation (TAC-->AA) at codon 329 in exon 6. Two homozygotes for Y329fs and one compound heterozygote for Y329fs and V311fs were identified from three different families. Two homozygous sisters for the D487_S488_F489 deletion were identified. CONCLUSION: The results confirmed the diagnostic value of the HPLC serum adrenal profile for 17alpha-hydroxylase deficiency. The D487_S488_F489 deletion had been identified in two previously genotyped Chinese families. In our present study, a third Chinese family with this mutation was identified, suggesting that this mutation is a prevalent CYP17 mutation in the Chinese population. The identification of Y329fs mutation in addition to three previously identified mutations at codon 329 suggests that codon 329 is an unstable point of the CYP17 gene. The mutations identified from our five patients appear to be random, but the recurrence of the Y329fs mutation may be attributed to a founder effect. Our studies suggest that 17alpha-hydroxylase deficiency may not be rare in the Chinese population.

Adolescent↗

PubMed2025

Unusual relapse dynamics in EGFR-mutated lung adenocarcinoma uncovered by genomic profiling: Insights from a case report.

Synchronous or metachronous multiple NSCLCs challenge clinical practice, particularly in distinguishing multiple separate primary lung cancers (SPLC) from intrapulmonary metastasis (IPM) for accurate staging and management. Here, we present a unique case of three resected lung adenocarcinomas (LUAD) from a single patient collected at different time points, all harboring the same EGFR p.L858R somatic driver mutation but exhibiting distinct clonal trajectories. Whole exome sequencing (WES) analysis revealed that the first tumor was an independent primary tumor, while the latter two tumors were clonally related. Our findings highlight the complexity of tumor progression and provide insights into clonal heterogeneity. This report underscores the importance of genomic profiling for discriminating SPLC from IPM and emphasizes that the detection of a single shared driver mutation is not sufficient to prove metastasis.

Humans↗