scholarly journals Synthesis and degradation rates of collagens in vivo in whole skin of rats, studied with 18O2 labelling

1986 ◽  
Vol 240 (2) ◽  
pp. 431-435 ◽  
Author(s):  
J A Molnar ◽  
N Alpert ◽  
J F Burke ◽  
V R Young
Keyword(s):  
Gas Chromatography Mass Spectrometry ◽  
Collagen Turnover ◽  
Growing Rats ◽  
Soluble Collagen ◽  
Insoluble Collagen ◽  
Degradation Rates ◽  
Labelling Procedure ◽  
Skin Biopsies ◽  
Synthesis And Degradation

Rats of synthesis and degradation in vivo of collagens in 0.5 M-acetic acid-soluble and -insoluble extracts from skins of three growing rats were determined by using a labelling procedure involving exposure of the animals to an atmosphere of 18O2 for 36 h. For comparison, rats also received injections of [2H]proline. Serial skin biopsies were taken at frequent intervals over 392 days. Enrichment of 18O and 2H in the hydroxyproline of the collagen fractions was determined by gas chromatography-mass spectrometry. Changes in size of the soluble and insoluble collagen pools were considered in the evaluation of isotope kinetic data. The insoluble collagen fraction showed no degradation. The efflux (mean +/- S.D., expressed as mumol of hydroxyproline) from the soluble collagen pool was estimated to be 59.9 +/- 1.9 per day from the 18O data, and 25.5 +/- 7.5 per day from the 2H results. The finding indicates significant reutilization of 2H-radiolabelled proline for hydroxyproline synthesis. From these isotope data and estimates of size of the collagen pools it was determined that 55% of the collagen disappearing from the soluble pool was due to maturation into insoluble collagens and 45% of the disappearance was a result of actual degradation of soluble collagen. These results confirm the utility of 18O2 as a non-reutilizable label for studies of collagen turnover in vivo.

scholarly journals Synthesis and degradation of collagens in skin of healthy and protein-malnourished rats in vivo, studied by 18O2 labelling

1988 ◽  
Vol 250 (1) ◽  
pp. 71-76 ◽  
Author(s):  
J A Molnar ◽  
N M Alpert ◽  
D A Wagner ◽  
S Miyatani ◽  
J F Burke ◽  
...  
Keyword(s):  
Collagen Synthesis ◽  
Collagen Turnover ◽  
Sprague Dawley ◽  
Growing Rats ◽  
Soluble Collagen ◽  
Insoluble Collagen ◽  
Sprague Dawley Rats ◽  
Skin Biopsies ◽  
Synthesis And Degradation

To explore the effects of growth retardation, caused by restricted protein intake, on collagen turnover in the whole skin, Sprague-Dawley rats (n = 20) were labelled with 18O2 and fed on either an adequate (18%) or a low (3%) lactalbumin diet. Skin biopsies were obtained at intervals during the following 6 months. Independent groups of animals (n = 186) were used to determine the size of the 0.5 M-acetic acid-soluble and -insoluble collagen pools in the entire skin of healthy and malnourished rats. Collagen was estimated by measurement of hydroxyproline. Soluble-collagen synthesis rates were equivalent to 99 +/- 8 mumol of hydroxyproline/day in healthy animals and 11 +/- 2 mumol/day in malnourished rats. Insoluble-collagen synthesis rates were 32 and 5 mumol of hydroxyproline/day in the healthy and protein-depleted rats respectively. The degradation of soluble collagen amounted to 37 +/- 8 and 6 +/- 2 mumol of hydroxyproline/day in the healthy and malnourished groups respectively. Efflux of collagen from the soluble collagen, defined as the sum of the rate of soluble collagen that is degraded plus that which matures into insoluble collagen, was 70 +/- 8 and 11 +/- 2 mumol of hydroxyproline/day in the healthy and malnourished groups respectively. Insoluble collagen was not degraded in either group. The fraction of soluble collagen leaving the pool that was converted into insoluble collagen was 0.46 in both diet groups. It is concluded that the turnover of soluble collagen is markedly decreased with malnutrition, but degradation and conversion into insoluble collagen account for the same proportions of efflux from the soluble-collagen pool as in rapidly growing rats.

scholarly journals Chemical changes associated with aging of collagen in vivo and in vitro

1969 ◽  
Vol 112 (4) ◽  
pp. 397-405 ◽  
Author(s):  
Kalindi Deshmukh ◽  
Marcel E. Nimni
Keyword(s):  
Absorption Spectrum ◽  
Neutral Salt ◽  
Unsaturated Aldehyde ◽  
Salt Solutions ◽  
Rat Skin ◽  
Soluble Collagen ◽  
Insoluble Collagen ◽  
Cross Links

Collagen extracted from rat skin by neutral-salt solutions contains less aldehydes than the more insoluble collagen fractions. The concentration of aldehydes in collagen is directly related to its capacity to form stable cross-linked gels, which do not redissolve on cooling and become more insoluble in a variety of reagents. Whereas the absorption spectrum of neutral-salt-soluble collagen treated with N-methylbenzothiazolone hydrazone resembles that of acetaldehyde, the more insoluble collagen fractions show increasing amounts of a component that behaves like an αβ-unsaturated aldehyde. The ratio between α- and β-sub-units present in a particular fraction of soluble collagen seems to be constant and independent of the age of the animal. Neutral-salt-soluble collagen, which has a low concentration of β-components, will generate intramolecular bonds if gelled at 37°. These intramolecular bonds seem to precede the formation of stable intermolecular cross-links, since these gels can redissolve when cooled to yield a soluble collagen with a higher content of β-components of intramolecular origin.

scholarly journals Effect of hypophysectomy on the rates of protein synthesis and degradation in rat liver

1979 ◽  
Vol 178 (3) ◽  
pp. 725-731 ◽  
Author(s):  
R D Conde
Keyword(s):  
Protein Synthesis ◽  
Protein Degradation ◽  
Rat Liver ◽  
Protein Metabolism ◽  
Plasma Proteins ◽  
Degradation Rates ◽  
Hypophysectomized Rats ◽  
Protein Synthesis And Degradation ◽  
Synthesis And Degradation

The effect of hypophysectomy on the protein metabolism of the liver in vivo was studied. Fractional rates of protein synthesis and degradation were determined in the livers of normal and hypophysectomized rats. Synthesis was measured after the injection of massive amounts of radioactive leucine. Degradation was estimated either as the balance between synthesis and accumulation of stable liver proteins or from the disappearance of radioactivity from the proteins previously labelled by the injection of NaH14CO3. The results indicate that: (1) hypophysectomy diminishes the capacity of the liver to synthesize proteins in vivo, mainly of those that are exported as plasma proteins; (2) livers of both normal and hypophysectomized rats show identical protein-degradation rates, whereas plasma proteins are degraded slowly after hypophysectomy.

Extensive changes in collagen synthesis and degradation during compensatory lung growth

1988 ◽  
Vol 255 (6) ◽  
pp. C754-C759 ◽  
Author(s):  
R. J. McAnulty ◽  
L. H. Staple ◽  
D. Guerreiro ◽  
G. J. Laurent
Keyword(s):  
Protein Synthesis ◽  
Collagen Synthesis ◽  
Collagen Degradation ◽  
Lung Growth ◽  
Compensatory Lung Growth ◽  
Fractional Rate ◽  
Degradation Rates ◽  
Protein Synthesis And Degradation ◽  
Synthesis And Degradation

Unilateral pneumonectomy in rats causes compensatory growth of the remaining lung. This growth involves rapid production of collagen and noncollagen proteins, but the mechanisms for these changes have not been fully investigated. Rates of collagen metabolism were measured using previously validated in vivo methods. Six days after pneumonectomy, a threefold increase in the fractional rate of collagen synthesis was observed (control 11.8 +/- 0.9%/day, pneumonectomy 30.0 +/- 4.6%/day). Collagen degradation rates also increased but returned to normal more rapidly than the synthesis rates. These changes in synthesis and degradation resulted in a 75% increase in collagen content by 28 days. Although degradation of extracellular collagens was apparently increased, the fraction degraded intracellularly decreased by approximately 30%. Noncollagen protein synthesis and degradation rates both increased by approximately 80% (control 44.3 +/- 3.4%/day, pneumonectomy 80.3 +/- 10.2%/day) with a slightly greater increase in synthesis that led to an 85% increase in noncollagen protein content 28 days after pneumonectomy. The data obtained show dramatic changes in protein synthesis and degradation during compensatory lung growth and indicate extensive remodeling of structural elements in lung tissue. The changes for intracellular collagen degradation provide further evidence that this pathway may have an important role in regulating collagen deposition.

scholarly journals A comparison of rates of protein turnover in rat diaphragm in vivo and in vitro

1986 ◽  
Vol 233 (1) ◽  
pp. 279-282 ◽  
Author(s):  
V R Preedy ◽  
D M Smith ◽  
P H Sugden
Keyword(s):  
Protein Synthesis ◽  
Protein Turnover ◽  
Rat Diaphragm ◽  
Degradation Rates ◽  
Protein Synthesis And Degradation ◽  
Synthesis And Degradation

Protein synthesis and degradation rates in diaphragms from fed or starved rats were compared in vivo and in vitro. For fed rats, synthesis rates in vivo were approximately twice those in vitro, but for starved rats rates were similar. Degradation rates were less in vivo than in vitro in diaphragms from either fed or starved rats.

scholarly journals Thyroid hormones and muscle protein turnover. The effect of thyroid-hormone deficiency and replacement in thryoidectomized and hypophysectomized rats

1981 ◽  
Vol 194 (3) ◽  
pp. 771-782 ◽  
Author(s):  
J G Brown ◽  
P C Bates ◽  
M A Holliday ◽  
D J Millward
Keyword(s):  
Protein Synthesis ◽  
Muscle Protein ◽  
Hormone Deficiency ◽  
Growing Rats ◽  
Hypophysectomized Rats ◽  
Ad Libitum ◽  
Protein Synthesis And Degradation ◽  
Rna Concentration ◽  
Synthesis And Degradation

We have investigated the effects of thyroidectomy, hypophysectomy and 3,3′,5-tri-iodothyronine replacement on protein synthesis and degradation in skeletal muscle in vivo. Thyroidectomy resulted in a decrease in the rate of protein synthesis as a result of a loss of RNA. However, RNA activity, the rate of protein synthesis per unit of RNA, was not decreased. This was the case in both young growing rats and mature nongrowing rats. Tri-iodothyronine treatment of thyroidectomized rats increased protein synthesis by increasing RNA concentration without changes in RNA activity, and this occurred even when food intake was restricted to prevent any increase in growth. The rate of protein degradation was decreased by thyroidectomy and increased by tri-iodo-thyronine replacement in both animals fed ad libitum and food-restricted animals. Hypophysectomy decreased protein synthesis by decreasing both RNA concentration and activity. these changes were reversed by tri-iodothyronine treatment even in the presence of persistent marked hypoinsulinaemia. This indicates that tri-iodothyronine can activate athe translational phase of protein synthesis in muscle in the absence of significant quantities of insulin. However, tri-iodothyronine does not seem to be obligatory for the maintenance of normal RNA activity in muscle, since in the thyroidectomized rat, in which plasma insulin concentrations are normal, RNA activity is maintained. From a consideration of the magnitude of changes in RNA activity observed in these experiments, it would appear that alterations in rates of elongation as well as initiation are involved in the changes in RNA activity.

scholarly journals Defects in autophagy lead to selective in vivo changes in turnover of cytosolic and organelle proteins in Arabidopsis

2021 ◽  
Author(s):  
Lei Li ◽  
Chun Pong Lee ◽  
Akila Wijerathna-Yapa ◽  
Martyna Broda ◽  
Marisa S. Otegui ◽  
...  
Keyword(s):  
Protein Synthesis ◽  
Protein Degradation ◽  
Degradation Rate ◽  
T Complex ◽  
Autophagy Induction ◽  
Degradation Rates ◽  
Specific Proteins ◽  
Protein Degradation Rate ◽  
Synthesis And Degradation

AbstractIdentification of autophagic protein cargo in plants by their abundance in autophagy related genes (ATG) mutants is complicated by changes in both protein synthesis and protein degradation. To detect autophagic cargo, we measured protein degradation rate in shoots and roots of Arabidopsis atg5 and atg11 mutant plants. These data show that less than a quarter of proteins changing in abundance are probable cargo and revealed roles of ATG11 and ATG5 in degradation of specific cytosol, chloroplast and ER-resident proteins, and a specialized role for ATG11 in degradation of proteins from mitochondria and chloroplasts. Our data support a role for autophagy in degrading glycolytic enzymes and the chaperonin containing T-complex polypeptide-1 complex. Autophagy induction by Pi limitation changed metabolic profiles and the protein synthesis and degradation rates of atg5 and atg11 plants. A general decrease in the abundance of amino acids and increase in several secondary metabolites in autophagy mutants was consistent with altered catabolism and changes in energy conversion caused by reduced degradation rate of specific proteins. Combining measures of changes in protein abundance and degradation rates, we also identify ATG11 and ATG5 associated protein cargo of low Pi induced autophagy in chloroplasts and ER-resident proteins involved in secondary metabolism.Single Sentence SummaryProtein cargo of autophagy in plants can be discovered by identifying proteins that increase in abundance and decrease in degradation rate in mutants deficient in autophagy machinery

scholarly journals Synthesis and degradation of collagen in the developing corium of the chick embryo

1968 ◽  
Vol 110 (3) ◽  
pp. 435-440 ◽  
Author(s):  
Robert J. Boucek ◽  
Vladimira Hlavackova
Keyword(s):  
Chick Embryo ◽  
Collagen Synthesis ◽  
Collagen Degradation ◽  
Collagen Metabolism ◽  
Collagen Turnover ◽  
Synthesis And Degradation

1. Indices of collagen synthesis and degradation were developed in a chick corium system in vitro. 2. These indices were determined by quantitatively measuring non-diffusible and diffusible hydroxy[14C]proline in the tissues after a standard period of incubation. 3. Under these incubation conditions collagen metabolism of the corium appears to be stable for at least 180min. 4. The indices of collagen synthesis and degradation seem to reflect the conditions of collagen metabolism in vivo. 5. A rapid collagen turnover occurs in the corium of the 13–14-day embryo owing to an accelerated collagen degradation at that period. 6. Epidermal elements may influence the synthesis as well as the degradation of collagen.

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