RESUMEN
Mice fed a chemically defined diet devoid of pyrroloquinoline quinone (PQQ) grew poorly, failed to reproduce, and became osteolathyritic. Moreover, severely affected mice had friable skin, skin collagen that was readily extractable into neutral salt solutions, and decreased lysyl oxidase. The identification of functional defects in connective tissue and the growth retardation associated with PQQ deprivation suggest that PQQ plays a fundamental role as a growth factor or vitamin.
Asunto(s)
Coenzimas/fisiología , Quinolonas/fisiología , Animales , Colágeno/metabolismo , Femenino , Sustancias de Crecimiento/fisiología , Ratones , Fenómenos Fisiológicos de la Nutrición , Cofactor PQQ , Quinolonas/deficiencia , Piel/metabolismoRESUMEN
Pyrroloquinoline quinone (PQQ) added to purified diets devoid of PQQ improves indices of perinatal development in rats and mice. Herein, PQQ nutritional status and lysine metabolism are described, prompted by a report that PQQ functions as a vitamin-like enzymatic cofactor important in lysine metabolism (Nature 422 [2003] 832). Alternatively, we propose that PQQ influences lysine metabolism, but by mechanisms that more likely involve changes in mitochondrial content. PQQ deprivation in both rats and mice resulted in a decrease in mitochondrial content. In rats, alpha-aminoadipic acid (alphaAA), which is derived from alpha-aminoadipic semialdehyde (alphaAAS) and made from lysine in mitochondria, and the plasma levels of amino acids known to be oxidized in mitochondria (e.g., Thr, Ser, and Gly) were correlated with changes in the liver mitochondrial content of PQQ-deprived rats, but not PQQ-supplemented rats. In contrast, the levels of NAD dependent alpha-aminoadipate-delta-semialdehyde dehydrogenase (AASDH), a cytosolic enzyme important to alphaAA production from alphaAAS, was not influenced by PQQ dietary status. Moreover, the levels of U26 mRNA were not significantly changed even when diets differed markedly in PQQ and dietary lysine content. U26 mRNA levels were measured, because of U26's proposed, albeit questionable role as a PQQ-dependent enzyme involved in alphaAA formation.
Asunto(s)
ADN Mitocondrial/metabolismo , Lisina/metabolismo , Cofactor PQQ/farmacología , Ácido 2-Aminoadípico/sangre , Ácido 2-Aminoadípico/metabolismo , Animales , Femenino , L-Aminoadipato-Semialdehído Deshidrogenasa/genética , L-Aminoadipato-Semialdehído Deshidrogenasa/metabolismo , Ratones , Estado Nutricional , Cofactor PQQ/sangre , Embarazo , Proteínas/genética , Proteínas/metabolismo , ARN Mensajero/metabolismo , Ratas , Ratas Sprague-DawleyRESUMEN
The turnover and degradation of mature elastin from the aortae of Japanese quail were estimated following injection with L-[U-14C]lysine by measuring the changes in specific activity of L-[U-14C]lysine and 14C-labelled desmosine and isodesmosine (crosslinking amino acids derived from lysyl residues) in elastin over a 39-week period. Only 5% of the variation in radioactivity could be attributed to changes in time. Therefore, it was concluded that the best estimates of mature elastin turnover are only quantifiable in years. Dietary cholesterol in amounts sufficient to induce plaque formatioin and fragmentation of the elastic lamina in the aorta did not significantly influence turnover time. It would appear that once the total pool of elastin in aorta is stabilized as mature fibers it is not subject to proteolysis or resynthesis of sufficient magnitude to result in measurable turnover.
Asunto(s)
Aorta/metabolismo , Coturnix/metabolismo , Elastina/metabolismo , Hipercolesterolemia/metabolismo , Animales , Radioisótopos de Carbono , Colesterol en la Dieta/farmacología , Desmosina/metabolismo , Femenino , Lisina/metabolismo , MasculinoRESUMEN
We have previously demonstrated that aorta elastin, a highly crosslinked protein, does not undergo turnover that is easily measured in vivo. Therefore, it was hypothesized that when proteolysis of elastin occurs, a positive increase in N-terminal amino acids should result. Such an increase would represent elastin-derived fragments held covalently in situ. A cyanate carbamylation procedure was used to estimate the changes in N-terminal amino acids in aorta elastin. To provide tissue for the studies, Japanese quail (3 weeks old) were fed diets with or without the addition of 1% cholesterol. It was found that, in normal birds, the number of N-terminal amino acid residues increased from two to approximately three residues per 800 total residues (or mole of tropoelastin) throughout sexual development (3 to 8 weeks, post-hatching), with little increase thereafter. In hypercholesterolemic birds, the rate of appearance of new N-terminal residues, particularly glutamine or glutamic acid, appeared enhanced throughout early development, but by sexual maturity the number of N-terminal amino acid residues in aorta elastin from cholesterol-fed birds was similar to that for the control birds. For each of the elastin samples analyzed, approximately one residue of glycine was recovered per 800 total residues. Other amino acids that predominated as N-terminal residues were serine, aspartic and glutamic acids.
Asunto(s)
Arterias/crecimiento & desarrollo , Colesterol en la Dieta/farmacología , Elastina/metabolismo , Envejecimiento , Animales , Aorta/crecimiento & desarrollo , Arterias/efectos de los fármacos , Coturnix , Elastina/aislamiento & purificación , Femenino , Masculino , Factores SexualesRESUMEN
In the growing chick a marked stimulation in soluble and mature arterial elastin synthesis occurs 2 and 5 weeks after hatching. Measurement of [3H]valine and [3H]proline incorporation into arterial soluble protein during this period indicated that most of the label is found in a 70 000 dalton protein subunit. The labeled soluble subunit had the characteristics of native soluble elastin or tropoelastin. During the period in which the greatest percentage increase in mature elastin occurs, the highest specific activities of soluble [3H]valine-labeled protein were observed. These changes were striking and suggest a developmental period for the growing chick in which factors related to elastin metabolism may be more easily studied.
Asunto(s)
Aorta Torácica/metabolismo , Pollos/metabolismo , Elastina/biosíntesis , Envejecimiento , Animales , ADN/metabolismo , Peso Molecular , Músculos/metabolismo , Miocardio/metabolismo , Prolina/metabolismo , Valina/metabolismoRESUMEN
The sulfation of ascorbic acid by an ascorbic acid sulphotransferase was investigated using rat liver and colon homogenates. When Na2 35 SO4 or 3'-phosphoadenylyl [35S]sulfate (P-Ado-P-35S) and ascorbic acid were used as substrates, chromatographic behavior of the reaction products on thin-layer cellulose suggested that ascorbic acid 2-[35S]sulfate was formed. With Na2 35SO4 as the source of radioactive sulfate in the assay system, ATP was found to be an obligatory cofactor. Incorporation of [35S]sulfate frofrom Na2 35SO4 into ascorbic acid 2-[35S]sulfate was also decreased when ATP sulfurylase inhibitors were added to the system. P-Ado-O35S alone in the assay without ATP was an extemely effective sulfating agent. In addition, liver and colon homogenates from vitamin A deficient and sufficient rats were used in one of the studies. Vitamin A deficiency appeared to have little effect on ascorbic acid 2-sulfate formation.
Asunto(s)
Ácido Ascórbico/metabolismo , Colon/metabolismo , Hígado/metabolismo , Ácidos Sulfúricos/metabolismo , Sulfurtransferasas/metabolismo , Deficiencia de Vitamina A/metabolismo , Animales , Cinética , Especificidad de Órganos , RatasRESUMEN
Radiochemical forms of pyrroloquinoline quinone (PQQ) are of utility in studies to determine the metabolic role and fate of PQQ in biological systems. Accordingly, we have synthesized [(14)C]PQQ using a tyrosine auxotrophic strain of Escherichia coli (AT2471). A construct containing the six genes required for PQQ synthesis from Klebsiella pneumoniae was used to transform the auxotrophic strain of E. coli. E. coli were then grown in minimal M9 medium containing 3.7x10(9) Bq/mmol [(14)C]tyrosine. At confluence, the medium was collected and applied to a DEAE A-25 anionic exchange column; [(14)C]PQQ was eluted using a KCl gradient (0-2 M in 0.1 M potassium phosphate buffer, pH 7.0). Radioactivity co-eluting as PQQ was next pooled, acidified and passed through a C-18 column; [(14)C]PQQ was eluted with a phosphate buffer (0.1 M, pH 7.0). Reverse phase HPLC (C-18) using either the ion-pairing agent trifluoroacetic acid (0. 1%) and an acetonitrile gradient or phosphoric acid and a methanol gradient were used to isolate [(14)C]PQQ. Fractions were collected and analyzed by liquid scintillation counting. (14)C-labelled compounds isolated from the medium eluted corresponding to the elution of various tyrosine-derived products or PQQ. The radioactive compound corresponding to PQQ was also reacted with acetone to form 5-acetonyl-PQQ, which co-eluted with a 5-acetonyl-PQQ standard, as a validation of [(14)C]PQQ synthesis. The specific activity of synthesized [(14)C]PQQ was 3.7x10(9) Bq/mmol [(14)C]PQQ, equal to that of [U-(14)C]tyrosine initially added to the medium.
Asunto(s)
Coenzimas/biosíntesis , Escherichia coli/genética , Genes Bacterianos , Klebsiella pneumoniae/genética , Quinolonas/metabolismo , Quinonas/metabolismo , Radioisótopos de Carbono , Cromatografía Líquida de Alta Presión , Coenzimas/genética , Escherichia coli/metabolismo , Klebsiella pneumoniae/metabolismo , Cofactor PQQ , PlásmidosRESUMEN
The rate of soluble elastin synthesis was estimated in lung explants from rats of differing ages to better define periods in lung development important to the deposition of lung elastin. Lungs from rat pups at days 1, 3, 7, 9, 12, 15, and 21 post-parturition and from adult rats were incubated in a defined medium containing L-[3H]valine. Following incubation, labelled soluble elastin (tropoelastin) was separated from other soluble proteins by coacervation and electrophoresis on polyacrylamide gels containing sodium dodecyl sulfate. The tropoelastin synthetic rate was then estimated after correcting for differences in recovery of radioactivity as tropoelastin and lung tissue L-[3H]valine specific activity. Maximal rates of elastin synthesis were observed in lung explants from 7-12-day-old rats. The rate of elastin synthesis during this period was 5-8-times the rate observed in adult rat lung (expressed per g of fresh lung) and represented approx. 2% of the total protein synthesis. Moreover, the values derived from lung explant culture for elastin synthesis were consistent with values for lung elastin deposition in the perinatal rat (5-10 micrograms elastin/h per g lung).
Asunto(s)
Elastina/biosíntesis , Pulmón/metabolismo , Envejecimiento , Animales , Pollos , Técnicas In Vitro , Pulmón/crecimiento & desarrollo , Músculo Liso Vascular/metabolismo , Ratas , Solubilidad , Tropoelastina/biosíntesis , Valina/metabolismoRESUMEN
Data from the in vivo incorporation of [3H]valine into fractions of elastin obtained from rat or mouse lung suggest that postnatal lung elastin synthesis occurs predominantly in the first 1 to 2 weeks of life. Very little [3H]valine was incorporated into lung elastin obtained from adult animals. When lung elastin from neonatal mice was radiochemically labelled with [14C]lysine as a single pulse, it was observed that the specific activity of the elastin expressed as the total dpm values as 14C per mg was not significantly altered over a 6 month period. Elastin appears to turn over very slowly in mouse lung with half-life best estimated in years.
Asunto(s)
Elastina/metabolismo , Pulmón/metabolismo , Animales , Animales Recién Nacidos , Elastina/biosíntesis , Semivida , Pulmón/crecimiento & desarrollo , Ratones , Ratas , Valina/metabolismoRESUMEN
Connective tissue matrix components were investigated using skin fibroblasts from normal or inbred scoliotic lines of chickens. Specifically, the fibroblasts were obtained from either an isogenic line or a backcross, derived by crossing the isogenic line with a pure line of scoliotic birds. From the backcross, both affected (35-45%) and non-affected (55-65%) progeny were produced. The affected birds had spinal curves greater than 20 degrees. Several abnormalities of connective tissue were observed when cells from scoliotic chicks were grown in culture: increased collagen extractability, decreased aggregatability of proteoglycans under associative conditions and lower than normal levels of hyaluronic acid. There was also less collagen deposited in the cell layer with proportionately increased amounts of collagen secreted into the culture media by cells from scoliotic versus normal chick fibroblasts. Values for collagen matrix stability, as estimated by extractability and net deposition, were intermediate for cells from the backcrossed, but non-affected, birds. Moreover, hyaluronidase, an enzyme that degrades hyaluronic acid, was abnormally elevated in the fibroblast cultures from scoliotic chicks. It is proposed that the increase in hyaluronidase contributes to the abnormalities observed in extracellular matrix components and may be a factor in the expression of scoliosis in susceptible birds.
Asunto(s)
Colágeno/metabolismo , Fibroblastos/metabolismo , Hialuronoglucosaminidasa/metabolismo , Proteoglicanos/metabolismo , Escoliosis/metabolismo , Animales , Células Cultivadas , Pollos , Matriz Extracelular/metabolismo , Ácido Hialurónico/metabolismo , Sustancias Macromoleculares , Proteína-Lisina 6-Oxidasa/metabolismoRESUMEN
Chick plasma contains inhibitor(s) against trypsin and elastase which also appear to retard the degradation of tropoelastin by arterial tissue extracts. Chick aorta extracts also contain similar inhibitors against elastase and trypsin. Both levels of the plasma inhibitor(s) and inhibitor(s) extracted from thoracic aorta increase during early stages of growth and maturation. There is a three- to four-fold increase in the levels of the inhibitor(s) in chick plasma and aorta between one to four weeks after hatching. Of particular interest are the observations that the presence of the inhibitor(s) retards the conversion of soluble elastin (tropoelastin) to smaller elastin peptides. Subsequently, it is speculated that in addition to other vital roles, such proteinase inhibitors may also act in regulating elastogenesis and elastin fiber formation.
Asunto(s)
Pollos/metabolismo , Elastina/análogos & derivados , Elastasa Pancreática/antagonistas & inhibidores , Tropoelastina/metabolismo , Inhibidores de Tripsina/metabolismo , Animales , Aorta Torácica/crecimiento & desarrollo , Aorta Torácica/metabolismo , Pollos/crecimiento & desarrollo , Elastina/metabolismo , Inhibidores Enzimáticos/sangre , Elastasa Pancreática/metabolismo , Inhibidores de Tripsina/sangreRESUMEN
Young rats weighing 150 g (initial weight) were fed diets sufficient or deficient in vitamin A. Postweaning rats were used in order to retard the rapid onset of vitamin A deficiency. The effects of the deficiency were studied with respect to impairment of hematopoietic function and anemia. Values for hemoglobin and hematocrit provided evidence of anemia before the signs of severe vitamin A deficiency became apparent. These included alopecia, ocular lesions, and low levels of retinol in plasma and liver. At the point where liver stores of vitamin A were virtually depleted, however, estimates for serum iron, hematocrit, and hemoglobin were elevated to control levels. The latter phenomenon appeared to result from hemoconcentration. These data suggest that anemia may be a component of vitamin A deficiency, but might be masked by the dehydration that accompanies severe depletion of vitamin A.
Asunto(s)
Anemia/etiología , Hematopoyesis , Deficiencia de Vitamina A/complicaciones , Alopecia/complicaciones , Animales , Deshidratación/complicaciones , Recuento de Eritrocitos , Eritrocitos Anormales/ultraestructura , Oftalmopatías/complicaciones , Hematócrito , Hemoglobinas/metabolismo , Hierro/sangre , Hígado/metabolismo , Ratas , Vitamina A/metabolismoRESUMEN
Recent studies of experimental vitamin A deficiency in man led the authors to conclude that anemia may result from lack of vitamin A. A review of numerous nutrition surveys in underdeveloped countries enhanced the suspicion that deficiency of vitamin A does contribute to the prevalence of anemia. Preliminary studies of vitamin A-deficient rats confirmed previous observations that anemia may result from lack of this vitamin. The livers of these animals had very low concentrations of vitamin A but normal or increased concentrations of iron. The finding of anemia is in contrast with other reports that vitamin A deficiency may cause elevated values for hemoglobin and hematocrit. The authors suggest that loss of taste and smell as a result of deficiency may account for refusal of experimental animals to eat and drink enough to prevent inanitation and dehydration. The resulting hemoconcentration may mask the true hematological picture, which is one of anemia.
Asunto(s)
Anemia/etiología , Hematopoyesis , Hemoglobinas/metabolismo , Deficiencia de Vitamina A/sangre , Adolescente , Adulto , Anemia/tratamiento farmacológico , Animales , Países en Desarrollo , Femenino , Compuestos Ferrosos/uso terapéutico , Humanos , Masculino , Persona de Mediana Edad , Ratas , Vitamina A/metabolismo , Vitamina A/uso terapéutico , Deficiencia de Vitamina A/complicaciones , Deficiencia de Vitamina A/tratamiento farmacológicoRESUMEN
Copper deficiency during embryonic and fetal development can result in numerous gross structural and biochemical abnormalities. Such a deficiency can arise through a variety of mechanisms, including low maternal dietary copper intake, disease-induced or drug-induced changes in maternal and conceptus copper metabolism, or both. These issues are discussed in this article along with the use of in vitro embryo culture models to study the mechanisms underlying copper deficiency-induced teratogenesis. Current data suggest that changes in free radical defense mechanisms, connective tissue metabolism, and energy production can all contribute to the dysmorphogenesis associated with developmental copper deficiency.
Asunto(s)
Anomalías Congénitas/etiología , Cobre/deficiencia , Cobre/fisiología , Desarrollo Embrionario y Fetal/efectos de los fármacos , Animales , Femenino , Enfermedades Genéticas Congénitas , Humanos , Embarazo , Resultado del Embarazo/genética , Especificidad de la EspecieRESUMEN
Protein-lysine 6-oxidase (lysyl oxidase) is a cuproenzyme that is essential for stabilization of extracellular matrixes, specifically the enzymatic cross-linking of collagen and elastin. A hypothesis is proposed that links dietary copper levels to dynamic and proportional changes in lysyl oxidase activity in connective tissue. Although nutritional copper status does not influence the accumulation of lysyl oxidase as protein or lysyl oxidase steady state messenger RNA concentrations, the direct influence of dietary copper on the functional activity of lysyl oxidase is clear. The hypothesis is based on the possibility that copper efflux and lysyl oxidase secretion from cells may share a common pathway. The change in functional activity is most likely the result of posttranslational processing of lysyl oxidase. Copper is essential for organic cofactor formation in amine oxidases such as lysyl oxidase. Copper-containing amine oxidases have peptidyl 2,4,5 tri(oxo)phenylalanine (TOPA) at their active centers. TOPA is formed by copper-catalyzed oxidation of tyrosine, which takes place as part of Golgi or trans-Golgi processing. For lysyl oxidase, recent evidence (Science 1996;273:1078-84) indicates that as an additional step, a lysyl group at the active center of lysyl oxidase reacts with TOPA or its precursor to form lysyl tyrosylquinone.
Asunto(s)
Cobre/metabolismo , Proteínas de la Matriz Extracelular/metabolismo , Proteína-Lisina 6-Oxidasa/metabolismo , Animales , Proteínas de la Matriz Extracelular/química , Aparato de Golgi/metabolismo , Humanos , Proteína-Lisina 6-Oxidasa/biosíntesis , Proteína-Lisina 6-Oxidasa/químicaRESUMEN
The Watanabe hereditary hyperlipidemic (WHHL) rabbit is an animal model that resembles humans with familial hyperlipidemia. In the thoracic aortae, there is also morphologic evidence of marked destruction of medial lamellar elastin fibers. Herein is provided the chemical evidence of elastolytic degradation. The levels of lysyl oxidase (L.Ox.), soluble elastin (SE) and insoluble elastin (IE) were estimated in thoracic aortae samples from New Zealand white (NZW) and WHHL rabbits at 6 months of age or 5 WHHL rabbits at 2.5 years of age. Enzyme-linked immunosorption assays (ELISA) were used in the L.Ox. and SE measurements. IE was measured following alkali extraction of aortae. There was a decrease in IE in thoracic aortae from Watanabe rabbits compared to NZW controls at 6 months of age (P < 0.1), and a further loss of IE in aortae from 2.5-year-old WHHL rabbits relative to the values at 6 months (P < 0.05). Average values for IE were: 130 mg/g for 6-month-old NZW, 100 mg/g for 6-month-old WHHL, and 60 mg/g for 2.5-year-old WHHL rabbits. Moreover, SE was only observed in aorta extracts from the older WHHL rabbits, a sign of elastolytic damage. There was also a five- to sixfold decrease in L.Ox. in the older vs. younger rabbits.
Asunto(s)
Aorta/metabolismo , Elastina/metabolismo , Hiperlipidemias/metabolismo , Envejecimiento/metabolismo , Animales , Modelos Animales de Enfermedad , Ensayo de Inmunoadsorción Enzimática , Hiperlipidemias/genética , Proteína-Lisina 6-Oxidasa/metabolismo , Conejos , SolubilidadRESUMEN
The mechanical integrity of bone is dependent on the bone matrix, which is believed to account for the plastic deformation of the tissue, and the mineral, which is believed to account for the elastic deformation. The validity of this model is shown in this study based on analysis of the bones of vitamin B6-deficient and vitamin B6-replete chick bones. In this model, when B6-deficient and control animals are compared, vitamin B6 deficiency has no effect on the mineral content or composition of cortical bone as measured by ash weight (63 +/- 6 vs. 58 +/- 3); mineral to matrix ratio of the FTIR spectra (4.2 +/- 0.6 vs. 4.5 +/- 0.2), line-broadening analyses of the X-ray diffraction 002 peak (beta 002 = 0.50 +/- 0.1 vs. 0.49 +/- 0.01), or other features of the infrared spectra. In contrast, collagen was significantly more extractable from vitamin B6-deficient chick bones (20 +/- 2% of total hydroxyproline extracted vs. 10 +/- 3% p < or = 0.001). The B6-deficient bones also contained an increased amount of the reducible cross-links DHLNL, dehydro-dihydroxylysinonorleucine, (1.03 +/- 0.07 vs. 0.84 +/- 0.13 p < or = 0.001); and a nonsignificant increase in HLNL, dehydro-hydroxylysinonorleucine, (0.51 +/- 0.03 vs. 0.43 +/- 0.03, p < or = 0.10). There were no significant changes in bone length, bone diameter, or area moment of inertia. In four-point bending, no significant changes in elastic modulus, stiffness, offset yield deflection, or fracture deflection were detected. However, fracture load in the B6-deficient animals was decreased from 203 +/- 35 MPa to 151 +/- 23 MPa, p < or = 0.01, and offset yield load was decreased from 165 +/- 9 MPa to 125 +/- 14 MPa, p < or = 0.05. Since earlier histomorphometric studies had demonstrated that the B6-deficient bones were osteopenic, these data suggest that although proper cortical bone mineralization occurred, the alterations of the collagen resulted in changes to bone mechanical performance.
Asunto(s)
Densidad Ósea/fisiología , Tibia/patología , Deficiencia de Vitamina B 6/patología , Animales , Fenómenos Biomecánicos , Pollos , Colágeno/metabolismo , Dipéptidos/metabolismo , Elasticidad , Hidroxiprolina/orina , Masculino , Fosfato de Piridoxal/sangre , Radiografía , Espectroscopía Infrarroja por Transformada de Fourier , Tibia/diagnóstico por imagen , Difracción de Rayos XRESUMEN
We used an antibody to rat Clara cell 10 KD secretory protein (CC10) to compare the abundance of CC10 in non-ciliated epithelium of bronchioles and bronchi by immunohistochemistry and laser scanning confocal microscopy (LSCM) in the reflectance mode. Three zones of reflectance intensity (high, medium, low), directly related to CC10 content, were used to distinguish subcellular compartments of differing densities. Two major compartments contained CC10: granules and endoplasmic reticulum. Bronchiolar cell granules had relatively even reflectance, a high CC10 concentration (0.92 mg/ml), and occupied 7.5% of the cell volume. Bronchial cell granules were bi-zonal, lower in CC10 concentration (0.83 mg/ml), and occupied less cell volume (2.3%). Low-reflecting endoplasmic reticulum occupied a greater cell volume in bronchioles than in bronchi (32.8% and 22.1%, respectively). An intermediate-density zone consisted of endoplasmic reticulum close to granules. CC10 abundance, expressed as ng stored per unit surface area of epithelial basal lamina, was more than three times greater in bronchioles than in proximal bronchi (1.50 ng/mm2 vs 0.42 ng/mm2). These data demonstrate that the process of CC10 secretion differs markedly in non-ciliated epithelium of bronchi and bronchioles. Identifiable mucous-goblet cells did not contain CC10. The LSCM provides a method for quantifying intracellular CC10 pools in intact lung cells and has the potential for quantifying other proteins in subcellular compartments.
Asunto(s)
Bronquios/química , Proteínas/análisis , Uteroglobina , Animales , Bronquios/citología , Gránulos Citoplasmáticos/química , Inmunohistoquímica , Rayos Láser , Masculino , Microscopía , Peso Molecular , Ratas , Ratas Sprague-DawleyRESUMEN
Elastic fibers are important for elasticity and extensibility of lung tissue. In the developing lung, elastic fibers appear in greatest numbers during the process or period of alveolarization . A variety of mesenchymal cells in lung appear responsible for elastin synthesis. Elastin is a novel protein both from the standpoint of its processing into elastic fibers and chemical properties. For example, elastin undergoes posttranslational modification before its assembly into fibers. These steps include limited proteolysis, hydroxylation of prolyl residues and the oxidative deamination of lysyl residues prior to their incorporation into the crosslinks that covalently bond together polypeptide chains of elastin. The crosslinking amino acids include lysinonorleucine , merodesmosine and desmosine isomers. A key enzyme that controls this process is lysyl oxidase. Lysyl oxidase is a copper metalloprotein whose activity is responsive to and modulated by environmental insults, nutrition deficiencies and the administration of various pharmacological agents. Regarding chemical properties, elastin is one of the most apolar proteins secreted by mammalian cells. Moreover, elastin is one of the most long-lived proteins secreted into the extracellular matrix. In relationship to its processing into elastic fibers and chemical properties, details related to major aspects of elastin metabolism as well as speculation on its potential as a factor in lung development and disease are discussed.
Asunto(s)
Elastina/metabolismo , Pulmón/crecimiento & desarrollo , Aminoácidos/metabolismo , Animales , Biotransformación , Aves/metabolismo , Fenómenos Químicos , Química , Humanos , Pulmón/metabolismo , Mamíferos/metabolismo , Pleura/metabolismo , Biosíntesis de Proteínas , Especificidad de la EspecieRESUMEN
Interstitial pulmonary fibrosis induced by intratracheal instillation of bleomycin (BL) involves an excess production of reactive oxygen species, unavailability of adequate levels of NAD and ATP to repair the injured pulmonary epithelium, and an overexuberant lung collagen reactivity followed by deposition of highly cross-linked mature collagen fibrils resistant to enzymatic degradation. In the present study, we have demonstrated that dietary supplementation with taurine and niacin offered almost complete protection against the lung fibrosis in a multidose BL hamster model. The mechanisms for the protective effect of taurine and niacin are multifaceted. These include the ability of taurine to scavenge HOCl and stabilize the biomembrane; niacin's ability to replenish the BL-induced depletion of NAD and ATP; and the combined effect of taurine and niacin to suppress all aspects of BL-induced increases in the lung collagen reactivity, a hallmark of interstitial pulmonary fibrosis. It was concluded from the data presented at this Conference that the combined treatment with taurine and niacin, which offers a multipronged approach, will have great therapeutic potential in the intervention of the development of chemically induced interstitial lung fibrosis in animals and humans.