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Normal variants of human mitochondrial DNA and translation products: the building of a reference data base.

A good standard reference for the highly polymorphic human mitochondrial DNA (mtDNA) sequence is essential for studies of normal and disease-related nucleotide variants in the mitochondrial genome. A consensus sequence for the human mitochondrial genome has been derived from thirteen unrelated mtDNA sequences. We report 128 nucleotide variants of the human mtDNA sequence, and 62 amino acid variants of the human mitochondrial translation products, observed in the coding region of these mtDNA sequences.

Amino Acid Sequence↗

Preliminary data suggest that mutations in the CgRP pathway are not involved in human sporadic cryptorchidism.

In testicular descent to the scrotum, a multistep process, many anatomical and hormonal factors play a role. Cryptorchidism occurs in about 1-2% of males and may cause secondary degeneration of the testes. Animal models have shown that abnormalities, in the calcitonin gene-related peptide (CgRP) activity, could be relevant in the pathogenesis of cryptorchidism. We performed a mutation screening by PCR exon amplification, single-strand conformation polymorphism (SSCP) and sequencing in four candidate genes, CgRPs (alphaCgRP, betaCgRP), their receptor (CgRPR) and the receptor component protein (CgRP-RCP), in 90 selected cases of idiopathic unilateral or bilateral cryptorchidism. Mutation screening of the coding regions and intron-exon boundaries revealed some polymorphic variants but no pathogenic sequence changes. These preliminary data suggest that these genes are not major factors for cryptorchidism in humans.

Adult↗

A novel mutation, Arg71Thr, in the delta-sarcoglycan gene is associated with dilated cardiomyopathy.

Approximately 20-35% of cases of idiopathic dilated cardiomyopathy are familial. DCM-associated mutations have been reported in 13 genes including the desmin, delta-sarcoglycan, and metavinculin genes. This study screened for variants in these genes in Finnish patients with DCM. All coding regions of the desmin and delta-sarcoglycan genes and the metavinculin-specific exon of the vinculin gene were screened in 52 DCM patients from eastern Finland by PCR-SSCP. We detected a novel mutation, Arg71Thr, in the delta-sarcoglycan gene in two members of a small DCM family. One of the mutation carriers fulfills diagnostic criteria for DCM and is also symptomatic. The other mutation carrier has slightly dilated left ventricle and well preserved systolic function. Therefore carriers of the Arg71Thr mutation had a relatively mild phenotype and a late onset of the disease. Disease-associated mutations were not found in the desmin gene or the metavinculin-specific exon of the vinculin gene. We conclude that the desmin and delta-sarcoglycan genes are not predominant disease-causing genes in patients with DCM in eastern Finland.

Adolescent↗

Isolation, characterisation and organisation of histone H1 genes in African trypanosomes.

A tandemly arranged gene family coding for histone H1 in African trypanosomes is described. Many variants, differing by some substitutions and/or deletions in their monotone and repetitive amino acid sequences, are found. The different variants can be sorted into three subtypes using their N-terminal region. PCR amplification experiments with primers specific to these three H1 subtypes suggest that the genes may be separated into two transcriptional units. Heterogeneity among species, subspecies and even strains was found. The transcripts are polyadenylated and the trans-splicing site is located very closely to the start codon. The intergenic regions are typical when compared to other polycistronic clusters described in trypanosomes. Amino acid sequence motifs may explain differences seen in chromatin compaction patterns between African and American trypanosomes.

Amino Acid Sequence↗

Alternative splicing model for the synthesis and secretion of the 20 kilodalton form of rat growth hormone.

The characterization of a 20 kilodalton (20 kD) variant of rat growth hormone is reported. The 20 kD variant from rat pituitary gland extracts was identified on Western immunoblots of polyacrylamide gels. It was also shown that pituitary tissue maintained in culture secretes the 20 kD form. A rat growth hormone cDNA fragment was used as a probe in S1 nuclease mapping experiments of rat pituitary poly (A) mRNA to detect the presence of two growth hormone mRNAs in the rat pituitary gland. The protected mRNAs correspond to the predicted sizes that would encode the 22 kD and 20 kD forms of growth hormone. The site of variation between the mRNAs maps to a potential alternative 3' splice site in the 5' end of exon 3 of the coding sequence. The results support the hypothesis that the 20 kD variant in rat is the product of an mRNA alternatively spliced in exon 3, as is the case for the human growth hormone.

Animals↗

The activation of RNA synthesis by somatic nuclei injected into amphibian oocytes.

Previous work has shown that nuclei of cultured cells or erythrocytes are transcriptionally activated when injected into the germinal vesicle of Xenopus oocytes. We now find that the total amount of stable RNA synthesized by an oocyte with injected nuclei is about twice that of an uninjected oocyte (approximately 15 ng/day). At least half of the RNA transcribed by the injected nuclei is low-molecular-weight RNA of discrete sizes, and is transcribed by RNA polymerase III. Part of this is attributable to a new class of gene (referred to as OAX) which makes a transcript about 180 nucleotides long, and which is activated by at least 50-fold in somatic nuclei injected into oocytes. OAX RNA is not a degradation or processing variant of ribosomal or 5 S RNA, and is not coded by mitochondrial DNA. It enters oocyte cytoplasm, but turns over with a half-life of less than 3 hr, as judged by the culture of enucleate oocyte cytoplasms for several days during which 4 and 5 S RNAs are stable. OAX RNA synthesis is not detected by labelling cultured cells or their nuclei. The results emphasize the selectivity with which components of an oocyte germinal vesicle activate genes in injected somatic nuclei.

Animals↗

Novel human BTB/POZ domain-containing zinc finger protein ZNF295 is directly associated with ZFP161.

Human ZNF295 protein harbors a BTB/POZ domain and multiple krüppel (C(2)H(2)) type zinc finger domains, and thus belongs to a family of POK (POZ and krüppel) transcription factor. We have identified many transcript variants generated by the alternative splicing in 5' non-coding exons, an intra-exonic splicing in a coding region, and the use of three polyadenylation signals in the 3' UTR. The intra-exonic splicing removes 603-bp coding sequence, and thus ZNF295 gene produces two protein isoforms: ZNF295L with 1066 amino acid residues and ZNF295S with 865 amino acid residues, containing 9 and 5 zinc finger domains, respectively. ZNF295 is ubiquitously expressed in human fetal and adult tissues. Analysis of transcription activity of ZNF295 using various promoter-reporters demonstrated that ZNF295 acts as a transcription repressor, and contains two separate regions for repression activity: the BTB/POZ domain and the central region between BTB/POZ and ZF domains. Both ZNF295L and ZNF295S could interact not only with themselves and each other, but also with another POK protein ZFP161 known to function as a transcription repressor and an activator. We postulated that ZNF295 may be involved in the bi-directional control of gene expression in concert with ZFP161.

Amino Acid Sequence↗

Germline alterations in the 53BP1 gene in breast and ovarian cancer families.

The conserved TP53-binding protein 1 (53BP1) is a central mediator of the DNA damage checkpoint and appears to be one of the sensors of DNA double-strand breaks (DSBs). Improper processing of DSBs can result in loss or rearrangement of genetic information, leading to cell death or tumorigenesis. 53BP1 interacts with both TP53 and ATM, key proteins involved in the monitoring of genomic integrity and regulation of apoptosis. 53BP1 is also required for the formation of BRCA1 foci and the C-terminal part of these two proteins display significant homology. Based on its biological function, the 53BP1 gene is a good candidate for being involved in cancer susceptibility. Consequently, in the current study patients belonging to 126 breast and/or ovarian cancer families were screened for germline mutations in the entire coding region of the 53BP1 gene. A number of sequence variants were found, but none of them appeared to associate with cancer predisposition. To our knowledge this is the first comprehensive screening of 53BP1 mutations in familial breast and ovarian cancer cases.

Breast Neoplasms↗

A novel myosin heavy chain gene in human chromosome 19q13.3.

A human myosin heavy chain gene was identified in chromosome 19q13 by computational sequence analysis, RT-PCR and DNA sequencing of the cDNA. The complete cDNA has a length of 6786 bp and comprises 41 exons (40 coding) included in 108 kb of genomic sequence. Alternative splicing variants were also identified. The gene is expressed in a multitude of tissues, but mainly in small intestine, colon and skeletal muscle. The putative protein (228 kDa) carries the common myosin domains and presents high homology with the non-muscle myosin heavy chains (MYH9 and MYH10) as well as the smooth muscle myosin heavy chain MYH11. Nevertheless, phylogenetic analysis indicated that these homologous proteins are more related among themselves than to MYH14, suggesting that possibly this myosin heavy chain should be classified in a new myosin-subfamily.

Blotting, Northern↗

Identification of the PPARA locus on chromosome 22q13.3 as a modifier gene in familial combined hyperlipidemia.

Familial combined hyperlipidemia (FCHL) is a common genetic lipid disorder that is present in 10% of patients with premature coronary artery disease (CAD). It was the objective of the present study to evaluate the possible involvement of the PPARA locus in the pathophysiology of FCHL. Mutation detection analyses of the six coding PPARA exons resulted in the identification of four novel variants, [C/T] intron 3, S234G, [G/A] intron 5, and [C/A] 3(') UTR in three FCHL probands, whereas no novel variants were identified in spouses. In a case-control study, markers D22S275 and D22S928 were shown not to be associated with FCHL. However, D22S928, mapped within 1Mb of the PPARA gene, was shown to have a modifying effect on plasma apoCIII concentrations (P=0.011) and the combined hyperlipidemic FCHL phenotype (P=0.038). In addition two PPARA polymorphisms in intron 2 and 7 were studied, but these were not associated with FCHL. The frequency of the L162V variant was less in FCHL probands (1.98%) compared to that in spouses (4.84%). These results clearly demonstrate the genetically complex nature of FCHL and identify the PPARA gene as a modifier of the FCHL phenotype.

Case-Control Studies↗

Genotype dependent QSAR for HIV-1 protease inhibition.

The development of drug-resistant viruses limits the therapeutic success of anti-HIV therapies. Some of these genetic HIV-variants display complex mutational patterns in their pol gene that codes for protease and reverse transcriptase, the most investigated molecular targets for antiretroviral therapy. In this paper, we present a computational structure-based approach to predict the resistance of a HIV-1 protease strain to amprenavir by calculating the interaction energy of the drug with HIV-1 protease. By considering the interaction energy per residue, we can identify what residue mutations contribute to drug-resistance. This approach is presented here as a structure-based tool for the prediction of resistance of HIV-1 protease toward amprenavir, with a view to use the drug-protein interaction-energy pattern in a lead-optimization procedure for the discovery of new anti-HIV drugs.

Carbamates↗

Structural characteristics of two wheat histone H2A genes encoding distinct types of variants and functional differences in their promoter activity.

To investigate the regulation of plant histone H2A gene expression, we isolated two H2A genes (TH254 and TH274) from wheat, which encode two variants of H2A. Both genes had an intron in the coding region. In the promoters, some characteristic sequences, such as Oct and Nona motifs, which are conserved among plant histone genes, were located in a short region (about 120 bp) upstream from the putative TATA box. Transient expression analyses of promoter activity with H2A-GUS fusion genes using tobacco protoplasts revealed novel types of positive cis-acting sequences in the TH254 promoter: a direct repeat of a 13 bp sequence (AGTTACATTATTG) and a stretch composed of an AT-rich sequence (ATATAGAAAATTAAAA) and a G-box (CACGTG). Quantitative S1 assay of the mRNA amounts from the TH254/GUS and TH274/GUS chimeric genes in stably transformed and cell cycle-synchronized tobacco cell lines showed that the promoters of both genes contained at least one cis-acting element responsible for S phase-specific expression. Histochemical analysis of transgenic tobacco plants carrying the chimeric genes showed that the promoters of the two H2A genes were active in developing seedlings and flower organs but were regulated in a different manner.

Amino Acid Sequence↗

Cloning and expression of human placental L-Dopa decarboxylase.

L-Dopa decarboxylase (DDC) is a pyridoxal 5-phosphate (PLP)-dependent enzyme that catalyses the decarboxylation of L-Dopa to dopamine. In this study we show the expression of DDC in human placental tissue and present data on the molecular cloning and in vitro expression of the active recombinant enzyme. Our analyses indicated the presence of both alternative DDC mRNA splice variants (neuronal and nonneuronal) in human placenta. Cloning of the coding region of the DDC cDNA into the pTrcHisA expression vector led to the production of the enzymatically active recombinant protein. The obtained recombinant enzyme specific activity values were in good agreement with the results obtained for the purified enzyme from human kidney. The availability of active recombinant human DDC could provide information leading to the better understanding of the enzyme's structure and substrate specificity, as well as its regulation and involvement in pathological conditions.

5' Untranslated Regions↗

Genome-wide annotation of human multi-nucleotide variants reveals widespread functional differences from single nucleotide variants.

Multi-nucleotide variants (MNVs) represent a crucial yet underexplored category of genetic variation. Despite previous studies highlighting the prevalence and potential biological impact of MNVs in populations, comprehensive identification and detailed functional annotation of MNVs remain challenging. Here, we develop MNVAnno, a toolbox for rapid identification and annotation of complex MNVs, and utilize it to identify 3,984,258 MNVs from 700,134 human samples, expanding the human MNV list to 8,199,654. Our analysis reveals that MNVs can not only lead to distinct amino acid changes from their constituent single-nucleotide variants, but also significantly impact the function of non-coding regions. Furthermore, through genome-wide association studies, we identify some MNVs associated with multiple cancers, and establish the Human MNV Database to facilitate MNV research. Our study emphasizes the importance of MNV annotation, broadens the human MNV landscape, and opens avenues for exploring genetic variation in phenotypes and diseases.

Humans↗

Sequence variations in the 5' upstream regions of the FBN1 gene associated with Marfan syndrome.

Marfan syndrome (MFS; OMIM#154700) is a connective tissue disorder characterized by manifestations in the ocular, skeletal and cardiovascular systems. MFS is caused by mutation in the fibrillin-1 gene (FBN1; OMIM#134797) and more than 550 mutations have been identified so far. FBN1 is approximately 230 kb in size and contains three evolutionarily conserved alternatively spliced exons B, A and C at the 5'end. In a first systematic attempt to associate sequence variations in the FBN1 5' alternatively spliced exons with MFS, we investigated 41 individuals fulfilling the diagnostic criteria of Ghent nosology or with features of MFS including at least one major criterion or involvement of two organ systems but not fulfilling a strict interpretation of the Ghent nosology, and known to be negative for mutations in the FBN1 exons 1-65 as well as the TGFBR2 and TGFBR1 coding regions. We identified five novel and one previously reported variants in the six unrelated probands and provide preliminary evidence for their role in pathogenesis.

5' Flanking Region↗

Characterisation, mutation detection, and association analysis of alternative promoters and 5' UTRs of the human dopamine D3 receptor gene in schizophrenia.

The dopamine D(3) receptor gene (DRD3) is a candidate for a number of psychiatric conditions including schizophrenia, bipolar disorder and alcohol and drug abuse. Previous studies have reported associations between polymorphisms in DRD3 and these disorders, but these findings may have reflected linkage disequilibrium with pathogenic variants that are further upstream. We have isolated and sequenced approximately 9 kb of genomic sequence upstream of the human DRD3 translational start site. Using 5' RACE, we have identified within this region three additional exons and two putative promoter regions which show promoter activity in three different cell lines. A 5' UTR identified only in lymphoblasts is spread over three exons and is 353 bp long. A second 5' UTR, found in adult and fetal brain, lymphocytes, kidney and placenta is spread over two exons and is 516 bp long. A 260-bp sequence within this 9 kb corresponds to a previously reported EST, but corresponding mRNA could not be found in the tissues above. The EST, 5' UTRs and putative promoter regions have been analysed for polymorphisms, revealing 10 single nucleotide polymorphisms, seven of which were tested for association in a large sample of unrelated patients with schizophrenia and matched controls. No associations were observed with schizophrenia. In addition we failed to replicate previous findings of association with homozygosity of the Ser9Gly variant. The results from this study imply that neither the coding nor the regulatory region of DRD3 plays a major role in predisposition to schizophrenia.

5' Untranslated Regions↗

A missense variation in human casein kinase I epsilon gene that induces functional alteration and shows an inverse association with circadian rhythm sleep disorders.

Recent studies have shown that functional variations in clock genes, which generate circadian rhythms through interactive positive/negative feedback loops, contribute to the development of circadian rhythm sleep disorders in humans. Another potential candidate for rhythm disorder susceptibility is casein kinase I epsilon (CKIepsilon), which phosphorylates clock proteins and plays a pivotal role in the circadian clock. To determine whether variations in CKIepsilon induce vulnerability to human circadian rhythm sleep disorders, such as delayed sleep phase syndrome (DSPS) and non-24-h sleep-wake syndrome (N-24), we analyzed all of the coding exons of the human CKIepsilon gene. One of the variants identified encoded an amino-acid substitution S408N, eliminating one of the putative autophosphorylation sites in the carboxyl-terminal extension of CKIepsilon. The N408 allele was less common in both DSPS (p = 0.028) and N-24 patients (p = 0.035) compared to controls. When DSPS and N-24 subjects were combined, based on an a priori prediction of a common mechanism underlying both DSPS and N-24, the inverse association between the N408 allele and rhythm disorders was highly significant (p = 0.0067, odds ratio = 0.42, 95% confidence interval: 0.22-0.79). In vitro kinase assay revealed that CKIepsilon with the S408N variation was approximately 1.8-fold more active than wild-type CKIepsilon. These results indicate that the N408 allele in CKIepsilon plays a protective role in the development of DSPS and N-24 through alteration of the enzyme activity.

Adult↗

Synthesis and expression in Escherichia coli of the gene encoding monocyte-derived neutrophil-activating factor: biological equivalence between natural and recombinant neutrophil-activating factor.

The neutrophil-activating factor (NAF) purified from the conditioned medium of lipopolysaccharide-stimulated human monocytes was sequenced and found to consist of 72 amino acids: SAKELRCQCIKTYSKPFHPKFIKELRVIESGPHCANTEIIVKLSDGRELCLDPKENWVQRVVEKFLKRA ENS. Purified preparations of natural NAF contained, in addition to this main form, minor amounts of three amino-terminal variants with 77 (+AVLPR), 70, and 69 residues. A gene coding for the 72-amino acid NAF was synthesized, cloned, and expressed in Escherichia coli. Western (immunologic) blot analysis of crude bacterial extracts, with an antiserum raised against natural NAF, revealed a single band that comigrated with natural NAF. Recombinant NAF purified to homogeneity had identical amino- and carboxyl-terminal sequences to the 72-amino acid natural NAF. Recombinant NAF was tested on human neutrophils and had the same activity and potency as natural NAF in inducing chemotaxis, rapidly increasing cytosolic free Ca2+, activating the respiratory burst, and releasing specific and azurophilic granular contents.

Amino Acid Sequence↗