[Blood protein changes in the nephrotic syndrome due to an intrinsic disease of the kidney. Description of the histological picture obtained by renal biopsy].
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Adolescent↗
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Results for “Intrinsically disordered protein”
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[Vitamin B12 and transcobalamin in chronic myeloproliferative disorders].
Although vitamin B12 is an essential coenzyme for DNA synthesis, humans, like other mammals, are incapable of synthesizing it. The role of intrinsic factor (IF) in B12 absorption is widely known, but, in fact there exists a much more intricate and complex mechanism for the effective assimilation of this important trace element in humans. B12 binding proteins play important roles in all stages of vitamin B12 metabolism. They are involved not only in its absorption, but also in its transport in serum, uptake to cells, storage in organs, enterohepatic circulation, and elimination of its analogues. Besides IF, well-known as a vitamin B12 binding protein found in gastric juice, there are other kinds of binding proteins found in human serum which are composed to transcobalamin (TC) I, II and III. Elevation of the vitamin B12 level in chronic myelogenous leukemia was first reported in the 1950s. Since then, B12 elevation has been found to occur in other kinds of chronic myeloproliferative disorders (CMPDs) as well and to be caused by an increase of serum TC. In CMPDs, either TCI or TCIII increases, but, the degree of elevation and the type of TC involved differs for each disorder. This article describes the changes in TC of CMPD patients. With the induction of the developed radioimmunoassay for R-type B12 binding protein, many cases have been examined. In addition, detailed qualitative analysis using DEAE cellulose column chromatography has been included for conditions not previously reported.(ABSTRACT TRUNCATED AT 250 WORDS)
Blast Crisis↗
Detection and characterisation of two missense mutations at a cleavage site in the factor VIII light chain.
Haemophilia A is an X-linked bleeding disorder caused by a deficiency of factor VIII. As an essential cofactor in the intrinsic clotting cascade, factor VIII is activated and subsequently inactivated by proteolytic cleavages involving factor IIa (thrombin), factor Xa and activated protein C (APC). Investigation of the thrombin cleavage sites at amino acids 372 and 1689 of the factor VIII protein by oligonucleotide screening, DNA amplification and direct sequencing, enabled us to identify two missense mutations in 441 unrelated haemophiliacs. A C-to-T transition, which leads to the substitution of cysteine for arginine at position 1689, was found in a severely affected patient and a previously undescribed G-to-A substitution, causing replacement of arginine1689 with histidine, was found in a patient with mild disease.
Base Sequence↗
An intrinsic neuronal defect operates in dystonia musculorum: a study of dt/dt<==>+/+ chimeras.
In the mouse mutant dystonia musculorum (dt), peripheral and central sensory axons develop focal swellings and degenerate. To identify the primary cellular target of the mutation, we have analyzed the spinal cords of dt/dt<==>+/+ aggregation chimeras. In these chimeras, characteristic swellings appeared only on the axons of mutant genotype neurons; the axons of wild-type neurons, identified by their expression of a transgene-encoded human neurofilament protein, were normal. This direct correlation of genotype and phenotype indicates that the dt mutation acts via a mechanism intrinsic to affected neurons. In addition, we show here that the dt mutation leads to a disorder of neurofilament processing in which phosphorylated neurofilament epitopes accumulate inappropriately in neuronal perikarya.
Animals↗
Loss of CBP acetyltransferase activity by PHD finger mutations in Rubinstein-Taybi syndrome.
Disruption of one copy of the human CREB binding protein (CBP or CREBBP) gene leads to the Rubinstein-Taybi syndrome (RTS), a developmental disorder characterized by retarded growth and mental functions, broad thumbs, broad big toes and typical facial abnormalities. The CREB binding protein (CBP) is an essential transcriptional coactivator for many different transcription factors. CBP has the intrinsic ability to acetylate histones and other proteins, which is regarded as an important step in transcription activation. In vitro studies have shown that this enzymatic activity critically depends on the integrity of a plant homeodomain (PHD)-type zinc finger in the HAT domain of CBP. We therefore investigated whether PHD finger mutations are present in RTS patients. Mutational analysis of 39 patients revealed eight novel heterozygous mutations in the HAT domain of CBP, one of which alters a conserved PHD finger amino acid (E1278K), while a second mutation deletes exon 22, which encodes the central region of the PHD finger. Functional analysis of these RTS-associated PHD finger mutants showed that they lacked in vitro acetyltransferase activity towards histones and CBP itself and displayed reduced coactivator function for the transcription factor CREB. Importantly, in EBV-transformed lymphoblastoid cells from the exon 22 deletion patient we found approximately 50% less endogenous CBP HAT activity. These findings therefore underscore the functional importance of the PHD finger in vivo and imply that reduction of CBP HAT activity, as exemplified here by disruption of the PHD finger, is sufficient to cause RTS.
Acetyltransferases↗
Studies of the inflammatory process and malignant potential of oral mucosal lichen planus.
Oral mucosal lichen planus (OMLP) is a well recognized mucosal disease with unknown aetiology. Considerable controversy exists as to whether OMLP is intrinsically premalignant, or if the disorder facilitates the development of oral mucosal squamous cell carcinoma (OMSCC) by external factors. The aim of the present studies was to investigate the expression of c-erbB-2 protein in the keratinocytes of the initial biopsies of oral mucosal disorders diagnosed as OMLP with no evidence of epithelial dysplasia and to compare the results with the expression of c-erbB-2 protein in subsequent biopsies obtained from the same patients. These results were compared with the findings from another 26 biopsies from patients with OMLP and control groups (patients with dysplasia with no evidence of OMLP, patients with OMSCC with no evidence of OMLP and normal oral mucosa). The expression of the c-erbB-2 protein was evaluated by immunohistochemical staining of the gene product with the avidin-biotin-complex method using both fresh frozen and paraffin-embedded tissue sections. Five of the initial biopsies from patients with OMLP expressed the c-erbB-2 protein and one did not. None of the OMLP cases that subsequently showed evidence of dysplasia expressed the c-erbB-2 protein and of the OMSCC specimens from the patients with OMLP, 2 were negative and 1 expressed c-erbB-2 protein. Within the other group of OMLP specimens 3 (3/26) were negative for c-erbB-2 staining. The specimens from the control groups all expressed the c-erbB-2 protein. The results indicated the probability of the absence of c-erbB-2 staining being an indication of a potential for neoplastic transformation in OMLP with dysplastic changes.
Carcinoma, Squamous Cell↗
Reversible adsorption and nonreversible insertion of Escherichia coli alpha-hemolysin into lipid bilayers.
Alpha-Hemolysin is an extracellular protein toxin (107 kDa) produced by some pathogenic strains of Escherichia coli. Although stable in aqueous medium, it can bind to lipid bilayers and produce membrane disruption in model and cell membranes. Previous studies had shown that toxin binding to the bilayer did not always lead to membrane lysis. In this paper, we find that alpha-hemolysin may bind the membranes in at least two ways, a reversible adsorption and an irreversible insertion. Reversibility is detected by the ability of liposome-bound toxin to induce hemolysis of added horse erythrocytes; insertion is accompanied by an increase in the protein intrinsic fluorescence. Toxin insertion does not necessarily lead to membrane lysis. Studies of alpha-hemolysin insertion into bilayers formed from a variety of single phospholipids, or binary mixtures of phospholipids, or of phospholipid and cholesterol, reveal that irreversible insertion is favored by fluid over gel states, by low over high cholesterol concentrations, by disordered liquid phases over gel or ordered liquid phases, and by gel over ordered liquid phases. These results are relevant to the mechanism of action of alpha-hemolysin and provide new insights into the membrane insertion of large proteins.
1,2-Dipalmitoylphosphatidylcholine↗
Growth hormone (GH) regulation of submandibular gland structure and function in the GH-deficient rat: upregulation of haptocorrin.
Based on localization studies of the GH receptor/binding protein (BP) in the gastrointestinal tract, we have recently demonstrated growth hormone regulation of gastric intrinsic factor. In order to define the role of GH in the submandibular gland (SMG) we have investigated the effect of GH on SMG structure and function with particular reference to haptocorrin. Bovine GH (65 micrograms/100 g body weight) was administered twice daily to adult male dwarf rats for 6 days (DW+) while control animals received vehicle (DW-). Administration of GH produced a significant increase in body weight (P < 0.001) and allometric increase in SMG weight (P = 0). There was no change in RNA or protein content per g SMG and GH administration produced a small decrease in DNA content normalized to SMG weight. Morphometric analysis of the SMG revealed a significant increase in the percentage area of the gland occupied by tubular (GH receptor/BP expressing) structures and a significant increase in the diameter of both the intralobular striated and granular convoluted tubules. The effect of GH on cellular proliferation in the ductular and acinar components was determined by the immunohistochemical detection of nuclear 5'-bromo-2'-deoxyuridine (BrdU) incorporated during a 2-h pulse of BrdU. GH treatment induced a 5.5-fold increase in the labelling index of tubular cells whereas the acinar cell labelling index increased only 3.3-fold. Soluble extracts of SMG were prepared for estimation of 57Co-cyanocobalamin (vitamin B12) binding. GH administration resulted in an increase in total 57Co-cyanocobalamin (CBL) binding per mg SMG protein. To determine the contribution of haptocorrin (R-protein) the amount of cobinamide dicyanide (CD) displaceable binding was calculated. GH administration produced a 70% increase in CD displaceable CBL binding per mg SMG indicating GH regulation of haptocorrin. A comparison of total SMG CBL binding and CD displaceable CBL binding between male and female rats detected no sex difference. Therefore sex-specific GH secretory profiles are unlikely to be of importance in the regulation of haptocorrin. In conclusion we have demonstrated that GH stimulates hypertrophy and hyperplasia of components of the SMG in the dwarf rat. The observed upregulation of haptocorrin may synergize with the GH-stimulated increase in intrinsic factor to facilitate absorption of CBL during the anabolic state.
Animals↗
Degradation of mutant proteins, underlying "loss of function" phenotypes, plays a major role in genetic disease.
Many Mendelian monogenic disorders are caused by loss of the function of a single protein. This can result from rapid degradation of the mutant protein by cellular proteases, which reduces the steady-state concentration of the protein within the cell. The susceptibility of a protein to such proteolytic breakdown depends upon its kinetics of monomer folding and oligomer assembly and upon the intrinsic (thermodynamic) stability of its functional native-state conformation. Other cellular proteins, notably molecular chaperones, promote correct protein folding and assembly and thus provide some protection against degradation. An accumulation of recent evidence indicates that premature or accelerated degradation of mutant proteins, provoked by aberrations in their conformation, occurs in various subcellular compartments and represents a significant and prevalent pathogenic mechanism underlying genetic diseases. Inter-individual variability in proteolytic and folding systems can in part explain why "simple monogenic diseases" often display inconsistent genotype-phenotype correlations which show these disorders to be in reality quite complex. Protein folding and degradation may also be modulated artificially using exogenous small molecules. The identification or design of compounds which can interact specifically with particular target proteins, and which in so doing can exert beneficial effects on protein folding, assembly and/or stability, is beginning to open up a new and remarkably promising avenue for the treatment of diverse genetic disorders.
Genetic Diseases, Inborn↗
Expression of B7 costimulatory molecules by salivary gland epithelial cells in patients with Sjögren's syndrome.
OBJECTIVE: To investigate the expression of B7 costimulatory molecules in the lymphoepithelial lesions of salivary gland (SG) biopsy tissues and in SG epithelial cell lines derived from patients with Sjögren's syndrome (SS). METHODS: B7.1 and B7.2 protein expression was studied by immunohistochemistry in minor SGs obtained from 11 patients with SS and 10 disease control patients with nonspecific sialadenitis and in cultured SG epithelial cell lines obtained from minor SGs from 15 SS patients and 15 control patients. B7.1 and B7.2 messenger RNA (mRNA) expression by SG epithelial cell lines was examined by reverse transcription-polymerase chain reaction (RT-PCR). RESULTS: In biopsy tissues from SS patients, but not control patients, ductal and acinar epithelial cells showed increased expression of both B7.1 and B7.2. Intense spontaneous B7.1 protein expression (as well as HLA-ABC, but not B7.2 or HLA-DR) was also found in 73% of SG epithelial cell lines from SS patients versus 13% of those from control patients (P < 0.01). Interferon-y treatment induced, or up-regulated, B7.1, B7.2, and HLA-DR expression in all SG epithelial cell lines tested. B7.1 and B7.2 expression by SG epithelial cell lines was also verified at the mRNA level by RT-PCR. CONCLUSION: Human SG epithelia are intrinsically capable of expressing B7 proteins upon activation. In SS patients, the expression of B7 molecules by SG epithelial tissues and by SG epithelial cell lines indicates the activated status of SG epithelial cells in this disorder and, possibly, their capacity for presenting antigens to T cells.
Adolescent↗
The human androgen receptor AF1 transactivation domain: interactions with transcription factor IIF and molten-globule-like structural characteristics.
The AR (androgen receptor) is a ligand-activated transcription factor and member of the steroid receptor superfamily. The AR responds to the ligands testosterone and dihydrotestosterone and activates multiple downstream genes required in development and reproduction. During the events of transactivation, the AR makes specific protein-protein interactions with several basal transcription factors such as TBP (TATA-box-binding protein) and TFIIF (transcription factor IIF). These interactions occur predominantly within a defined region termed AF1 (activation function-1) located within the highly disordered N-terminal domain of the receptor. Our focus is on the structural aspects of AF1 and how this flexible and disordered domain generates functional interactions with regulators of transcription. Our working hypothesis is that AR-AF1 domain exhibits induced folding when contacted by transcription regulators (such as TFIIF) into a more compact and 'active' conformation, enabling further co-regulator recruitment and ultimately transcription. Structural flexibility and intrinsic disorder of AR-AF1 were studied using predictive algorithms and fluorescence spectroscopy under different experimental conditions and the results revealed this domain retains characteristics indicative of molten-globule or pre-molten-globule-like structures. We hypothesize that this partially folded intermediate state is important for, and enables the AF1 domain to make, multiple protein-protein interactions. The structural aspects of AR-AF1 and interactions with TFIIF are discussed.
Amino Acid Sequence↗
Editorial: Congenital disorders of vitamin B12 transport and their contribution to concepts.
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Anemia, Macrocytic↗
Electron paramagnetic resonance measurements of the hydration of Mn(II) in ternary complexes with GDP and ras p21 proteins.
Electron paramagnetic resonance (EPR) spectroscopy has been used to determine the hydration numbers of Mn(II) in complexes with GDP and three forms of ras p21. EPR signals of Mn(II) in the GDP complex with viral-Harvey p21pRAS1 (Arg 12, Thr 59), p21EC (Gly 12, Thr 59), and p21EJ (Val 12, Thr 59) have narrow line-widths that permit ready observation of inhomogeneous broadening from unresolved superhyperfine coupling with the nuclear spin of 17O of directly coordinated oxygen ligands. Quantitative analysis of the lineshapes for the samples in H2 17O-enriched water indicates that four water ligands coordinate to the metal ion in the GDP complexes with all three proteins. The four solvent ligands, together with an oxygen from the beta-phosphate group of GDP, leave space for only one ligand from the protein. An X-ray diffraction-derived model for the MgII beta-gamma-imidoguanosine-5'-triphosphate complex with p21 shows coordination of Mg(II) to the beta- and gamma-phosphate groups of the nucleotide as well as to the hydroxyl groups of Thr 35 and Ser 17 (Pai, E.F., Kabusch, W., Krengel, U., Holmes, K. H., John, J., and Wittinghofer, A., 1989, Nature (London) 341, 209-214). Thus, upon conversion of the nucleotide from a triphosphate to a diphosphate, solvent replaces both the gamma-phosphate of the nucleotide and one of the protein ligands. The EPR results are consistent with a recent X-ray crystallographic model for the p21-MgIIGDP complex (Milburn, M. V., Tong, L., DeVos, A. M., Brunger, A., Yamaizumi, Z., Nishimura, S., and Kim, S.-H., 1990, Science 247, 939-945). EPR spectra of complexes with the three forms of ras p21 differ with respect to the intrinsic linewidths of the EPR signals. These subtle differences in linewidth appear to originate from slight differences in local disorder near the metal-nucleotide binding site.
Electron Spin Resonance Spectroscopy↗
Proliferating cell nuclear antigen (PCNA) expression in chronic lymphocytic leukemia (CLL).
Chronic Lymphocytic Leukemia (CLL) is usually an indolent disorder which in some patients assumes an aggressive clinical course. In order to assess at presentation the prognosis of a given patient, several staging systems and prognostic variables have been proposed including the expression of the Proliferating Cell Nuclear Antigen (PCNA). PCNA is a 36 kd nuclear protein, the regulation of which is cell cycle-dependent. In CLL, PCNA levels correlate with cell proliferation, clinical stage and the lymphocyte doubling time (LDT). Furthermore, preliminary data suggests that PCNA expression may also predict response to Fludarabine-based chemotherapy. Since PCNA is a cofactor for Delta DNA polymerase, PCNA overexpression in CLL may also reflect the intrinsic DNA repair activity of the leukemic cells and thus their resistance to chemotherapy. Further studies aiming at modulation of PCNA expression in CLL cells may clarify this issue and may offer a future new therapeutic strategy with which to treat this disorder.
Antigens, Neoplasm↗
Coupling endoplasmic reticulum stress to the cell death program.
The endoplasmic reticulum (ER) regulates protein synthesis, protein folding and trafficking, cellular responses to stress and intracellular calcium (Ca(2+)) levels. Alterations in Ca(2+) homeostasis and accumulation of misfolded proteins in the ER cause ER stress that ultimately leads to apoptosis. Prolonged ER stress is linked to the pathogenesis of several different neurodegenerative disorders. Apoptosis is a form of cell death that involves the concerted action of a number of intracellular signaling pathways including members of the caspase family of cysteine proteases. The two main apoptotic pathways, the death receptor ('extrinsic') and mitochondrial ('intrinsic') pathways, are activated by caspase-8 and -9, respectively, both of which are found in the cytoplasm. Recent studies point to the ER as a third subcellular compartment implicated in apoptotic execution. Here, we review evidence for the contribution of various cellular molecules that contribute to ER stress and subsequent cellular death. It is hoped that dissection of the molecular components and pathways that alter ER structure and function and ultimately promote cellular death will provide a framework for understanding degenerative disorders that feature misfolded proteins.
Apoptosis↗
Protein imperfections: separating intrinsic from extrinsic variation of torsion angles.
In this paper, the variation of the values of dihedral angles in proteins is divided into two categories by analyzing distributions in a database of structures determined at a resolution of 1.8 A or better [Lovell et al. (2003), Proteins Struct. Funct. Genet. 50, 437-450]. The first analysis uses the torsion angle for the Calpha-Cbeta bond (chi1) of all Gln, Glu, Arg and Lys residues ('unbranched set'). Plateaued values at low B values imply a root-mean-square deviation (RMSD) of just 9 degrees for chi1 related to intrinsic structural differences between proteins. Extrapolation to high resolution gives a value of 11 degrees , while over the entire database the RMSD is 13.4 degrees . The assumption that the deviations arise from independent intrinsic and extrinsic sources gives approximately 10 degrees as the RMSD for chi1 of these unbranched side chains arising from all disorder and error over the entire set. It is also found that the decrease in chi1 deviation that is correlated with higher resolution structures is almost entirely a consequence of the higher percentage of low-B-value side chains in those structures and furthermore that the crystal temperature at which diffraction data are collected has a negligible effect on intrinsic deviation. Those intrinsic aspects of the distributions not related to statistical or other errors, data incompleteness or disorder correlate with energies of model compounds computed with high-level quantum mechanics. Mean side-chain torsion angles for specific rotamers correlate well with local energy minima of Ace-Leu-Nme, Ace-Ile-Nme and Ace-Met-Nme. Intrinsic RMSD values in examples with B < or = 20 A2 correlate inversely with calculated values for the relevant rotational energy barriers: from a low of 6.5 degrees for chi1 of some rotamers of Ile to a high of 14 degrees for some Met chi3 for fully tetrahedral angles and much higher for chi angles around bonds that are tetrahedral at one end and planar at the other (e.g. 30 degrees for chi2 of the gauche- rotamer of Phe). For the lower barrier Met chi3 rotations there are relatively more well validated cases near eclipsed values and calculated torques from the rest of the protein structure either confine or force the Cepsilon atom into the strained position. These results can be used to evaluate the variability and accuracy of chi angles in crystal structures and also to decide whether to restrain side-chain angles in refinement as a function of the resolution and atomic B values, depending on whether one aims for a realistic distribution of values or a spread that is statistically suitable to the probable data-set errors.
Carbon↗
Abnormal transglutaminase 1 expression pattern in a subset of patients with erythrodermic autosomal recessive ichthyosis.
An autosomal recessive ichthyosis characterized by collodian membrane at birth followed by generalized skin redness and fine, light-colored scales has been termed nonbullous congenital ichthyosiform erythroderma (CIE). CIE has often been classified together with the other major form of recessive ichthyosis without internal organ involvement, lamellar ichthyosis, which is characterized by minimal erythema and a coarser, darker scale pattern. Recently, autosomal recessive ichthyosis has been associated with keratinocyte transglutaminase (TGase1) defects in some patients. This group of diseases, however, is genetically heterogeneous and TGase1 abnormalities in CIE have not been clearly described. Therefore we examined TGase1 expression in five patients with CIE and three with classic lamellar ichthyosis. Although lamellar ichthyosis patients displayed no TGase1 expression, an abnormal intracellular accumulation of TGase1 was observed in four of five CIE patients. This finding was specific and was not observed in other skin disorders characterized by erythema and abnormal cornification, including erythrodermic psoriasis, atopic dermatitis, epidermolytic hyperkeratosis, and Netherton's syndrome. CIE keratinocytes with abnormal TGase1 localization expressed full-length TGase1 mRNA and protein but demonstrated transglutaminase activity intermediate between normal and the minimal activity seen in lamellar ichthyosis patient cells. The abnormal TGase1 expression pattern and CIE clinical features were recapitulated in epidermis regenerated in vivo on immune deficient mice from CIE patient keratinocytes. These studies describe a specific abnormality in TGase1 intrinsic to keratinocytes in a subset of CIE patients and suggest that this abnormality may be involved in the disordered epidermal differentiation seen in this disorder.
Humans↗
Characterization of a mutant form of SecA that alleviates a SecY defect at low temperature and shows a synthetic defect with SecY alteration at high temperature.
The secY205 mutant is cold-sensitive for protein export, with an in vitro defect in supporting ATP- and preprotein-dependent insertion of SecA into the membrane. We characterized SecA81 with a Gly516 to Asp substitution near the minor ATP-binding region, which suppresses the secY205 defect at low temperature and exhibits an allele-specific synthetic defect with the same SecY alteration at 42 degrees C. The overproduced SecA81 aggregated in vivo at temperatures above 37 degrees C. Purified SecA81 exhibited markedly enhanced intrinsic and membrane ATPase activities at 30 degrees C, while it was totally inactive at 42 degrees C. The trypsin digestion patterns indicated that SecA81 has some disorder in the central region of SecA, which encompasses residues 421-575. This conformational abnormality may result in unregulated ATPase at low temperature as well as the thermosensitivity of the mutant protein. In the presence of both proOmpA and the wild-type membrane vesicles, however, the thermosensitivity was alleviated, and SecA81 was able to catalyze significant levels of proOmpA-stimulated ATP hydrolysis as well as proOmpA translocation at 42 degrees C. While SecA81 was able to overcome the SecY205 defect at low temperature, the SecY205 membrane vesicles could not significantly support the translocation ATPase or the proOmpA translocation activity of SecA81 at 42 degrees C. The inactivated SecA81 molecules seemed to jam the translocase since it interfered with translocase functions at 42 degrees C. Based on these results, we propose that under preprotein-translocating conditions, the SecYEG channel can stabilize and activate SecA, and that this aspect is defective for the SecA81-SecY205 combination. The data also suggest that the conformation of the central region of SecA is important for the regulation of ATP hydrolysis and for the productive interaction of SecA with SecY.
ATP-Binding Cassette Transporters↗