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Fuchs M, Gerlach J, Unger J, Encke J, Smith M, Neuhaus P, Nündel M, Riedel E. α-Keto acid metabolism by hepatocytes cultured in a hybrid liver support bioreactor. Int J Artif Organs 2018. [DOI: 10.1177/039139889401701008] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Isolated pig liver cells cultured using a perfusion technique were analyzed over 39 days to test their ability to change the perfusate α-keto acid profile. While the pyruvate concentration in the culture medium decreased as of the first day, the α-ketoglutarate (KG), α-ketoisocaproate (KIC), α-ketoisovalerate (KIV) and α-ketoβ-methyl-n-valerate (KMV) were synthesized immediately and released by the liver cells. The metabolic capacity of the cell culture system increased up to day 10, decreased during the following 5 days and reached a steady state beyond day 15, which was maintained for at least 30 days. The branched chain α-keto acid release, in particular α-ketoisocaproate, reflects an effective transamination capacity of the newly developed culture system and shows an intact protein biosynthesis for at least 30 days in vitro.
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Affiliation(s)
- M. Fuchs
- Institut für Biochemie, Freie Universität Berlin, Berlin - Germany
| | - J. Gerlach
- Klinikum Rudolf Virchow, Chirurgische Klinik, Freie Universität Berlin, Berlin - Germany
| | - J. Unger
- Klinikum Rudolf Virchow, Chirurgische Klinik, Freie Universität Berlin, Berlin - Germany
| | - J. Encke
- Klinikum Rudolf Virchow, Chirurgische Klinik, Freie Universität Berlin, Berlin - Germany
| | - M. Smith
- Bioengineering Unit, University of Strathclyde, Glasgow - UK
| | - P. Neuhaus
- Klinikum Rudolf Virchow, Chirurgische Klinik, Freie Universität Berlin, Berlin - Germany
| | - M. Nündel
- Institut für Biochemie, Freie Universität Berlin, Berlin - Germany
| | - E. Riedel
- Institut für Biochemie, Freie Universität Berlin, Berlin - Germany
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Chen W, Smeekens JM, Wu R. Systematic study of the dynamics and half-lives of newly synthesized proteins in human cells. Chem Sci 2016; 7:1393-1400. [PMID: 29910897 PMCID: PMC5975921 DOI: 10.1039/c5sc03826j] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2015] [Accepted: 11/15/2015] [Indexed: 12/22/2022] Open
Abstract
Protein dynamics are essential in regulating nearly every cellular event, and aberrant proteostasis is the source of many diseases. It is extraordinarily difficult to globally study protein dynamics and accurately measure their half-lives. Here we have developed a chemical proteomics method integrating protein labeling, click chemistry and multiplexed proteomics, which overcomes current challenges with existing methods. Labeling with both azidohomoalanine (AHA) and heavy lysine allows us to selectively enrich newly synthesized proteins, clearly distinguish them from existing proteins, and reduce the impact of heavy amino acid recycling. Moreover, multiplexed proteomics enables us to quantify proteins at multiple time points simultaneously, thus increasing the accuracy of measuring protein abundance changes and their half-lives. Systematic investigation of newly synthesized protein dynamics will provide insight into proteostasis and the molecular mechanisms of disease.
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Affiliation(s)
- Weixuan Chen
- School of Chemistry and Biochemistry and the Petit Institute for Bioengineering and Bioscience , Georgia Institute of Technology , Atlanta , Georgia 30332 , USA . ; ; Tel: +1-404-385-1515
| | - Johanna M Smeekens
- School of Chemistry and Biochemistry and the Petit Institute for Bioengineering and Bioscience , Georgia Institute of Technology , Atlanta , Georgia 30332 , USA . ; ; Tel: +1-404-385-1515
| | - Ronghu Wu
- School of Chemistry and Biochemistry and the Petit Institute for Bioengineering and Bioscience , Georgia Institute of Technology , Atlanta , Georgia 30332 , USA . ; ; Tel: +1-404-385-1515
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3
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Caballero VJ, Mendieta JR, Lombardo D, Saceda M, Ferragut JA, Conde RD, Giudici AM. Liver damage and caspase-dependent apoptosis is related to protein malnutrition in mice: effect of methionine. Acta Histochem 2015; 117:126-35. [PMID: 25575574 DOI: 10.1016/j.acthis.2014.11.012] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2014] [Revised: 11/28/2014] [Accepted: 11/29/2014] [Indexed: 01/18/2023]
Abstract
This study aimed to determine whether the effects on the mouse liver caused by three periods of feeding a protein-free diet for 5 days followed by a normal complete diet for 5 days (3PFD-CD) are prevented by a constant methionine supply (3PFD+Met-CD). The expressions of carbonic anhydrase III (CAIII), fatty acid synthase (FAS), glyceraldehyde 3-phosphate dehydrogenase (GAPDH) and glutathione S-transferase P1 (GSTP1) were assessed by proteomics and reverse transcriptase-polymerase chain reactions. The liver redox status was examined by measuring the activities of superoxide dismutase (SOD) and catalase (CAT), as well as protein carbonylation. Because oxidative stress can result in apoptosis, the activity and content of caspase-3, as well as the x-linked inhibitor of the apoptosis protein (XIAP) and mitochondrial caspase-independent apoptosis inducing factor (AIF) contents were assessed. In addition, the liver histomorphology was examined. Compared to the controls fed a normal complete diet throughout, feeding with 3PFD-CD increased the FAS content, decreased the CAIII content, decreased both the SOD and CAT activities, and increased protein carbonylation. It also activated caspase-3, decreased the XIAP content, decreased the AIF content, increased the number of GSTP1-positive foci and caspase-3-positive cells, and caused fatty livers. Conversely, the changes were lessened to varying degrees in mice fed 3PFD+Met-CD. The present results indicate that a regular Met supply lessens the biochemical changes, damage, and caspase-dependent apoptosis provoked by recurrent dietary amino acid deprivation in the mouse liver.
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Affiliation(s)
- Verónica J Caballero
- Biological Research Institute, Faculty of Natural Sciences, National University of Mar del Plata - CONICET, CC 1245, CP 7600 Mar del Plata, Argentina
| | - Julieta R Mendieta
- Biological Research Institute, Faculty of Natural Sciences, National University of Mar del Plata - CONICET, CC 1245, CP 7600 Mar del Plata, Argentina
| | - Daniel Lombardo
- Institute of Research and Technology in Animal Reproduction (INITRA), Faculty of Veterinary Science. University of Buenos Aires, Av. Chorroarín 280, C1427CWO Buenos Aires, Argentina
| | - Miguel Saceda
- Institute of Molecular and Cellular Biology, University Miguel Hernandez, Building Torregaitán, Avda de la Universidad s/n, 03202, Elche, Spain
| | - José Antonio Ferragut
- Institute of Molecular and Cellular Biology, University Miguel Hernandez, Building Torregaitán, Avda de la Universidad s/n, 03202, Elche, Spain
| | - Rubén D Conde
- Biological Research Institute, Faculty of Natural Sciences, National University of Mar del Plata - CONICET, CC 1245, CP 7600 Mar del Plata, Argentina
| | - Ana M Giudici
- Biological Research Institute, Faculty of Natural Sciences, National University of Mar del Plata - CONICET, CC 1245, CP 7600 Mar del Plata, Argentina.
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4
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Neufeld TP. Autophagy and cell growth--the yin and yang of nutrient responses. J Cell Sci 2012; 125:2359-68. [PMID: 22649254 DOI: 10.1242/jcs.103333] [Citation(s) in RCA: 72] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
As a response to nutrient deprivation and other cell stresses, autophagy is often induced in the context of reduced or arrested cell growth. A plethora of signaling molecules and pathways have been shown to have opposing effects on cell growth and autophagy, and results of recent functional screens on a genomic scale support the idea that these processes might represent mutually exclusive cell fates. Understanding the ways in which autophagy and cell growth relate to one another is becoming increasingly important, as new roles for autophagy in tumorigenesis and other growth-related phenomena are uncovered. This Commentary highlights recent findings that link autophagy and cell growth, and explores the mechanisms underlying these connections and their implications for cell physiology and survival. Autophagy and cell growth can inhibit one another through a variety of direct and indirect mechanisms, and can be independently regulated by common signaling pathways. The central role of the mammalian target of rapamycin (mTOR) pathway in regulating both autophagy and cell growth exemplifies one such mechanism. In addition, mTOR-independent signaling and other more direct connections between autophagy and cell growth will also be discussed.
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Affiliation(s)
- Thomas P Neufeld
- Department of Genetics, Cell Biology and Development, University of Minnesota, Minneapolis, MN 55455, USA.
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5
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Caballero VJ, Mendieta JR, Giudici AM, Crupkin AC, Barbeito CG, Ronchi VP, Chisari AN, Conde RD. Alternation between dietary protein depletion and normal feeding cause liver damage in mouse. J Physiol Biochem 2010; 67:43-52. [PMID: 20878513 DOI: 10.1007/s13105-010-0047-1] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2010] [Accepted: 09/15/2010] [Indexed: 01/12/2023]
Abstract
The effect of frequent protein malnutrition on liver function has not been intensively examined. Thus, the effects of alternating 5 days of a protein and amino acid-free diet followed by 5 days of a complete diet repeated three times (3 PFD-CD) on female mouse liver were examined. The expression of carbonic anhydrase III (CAIII), fatty acid synthase (FAS), glyceraldehyde 3-phosphate dehydrogenase (GAPDH) and glutathione S-transferase P1 (GSTP1) in liver were assessed by proteomics, reverse transcriptase-polymerase chain reaction and Northern blotting. The activities of liver GSTs, glutathione reductase (GR) and catalase (CAT), as well as serum glutamic-oxaloacetic transaminase (SGOT) and glutamic-pyruvic transaminase (SGPT) were also tested. Additionally, oxidative damage was examined by measuring of protein carbonylation and lipid peroxidation. Liver histology was examined by light and electron microscopy. Compared with control mice, 3 PFD-CD increased the content of FAS protein (+90%) and FAS mRNA (+30%), while the levels of CAIII and CAIII mRNAs were decreased (-48% and -64%, respectively). In addition, 3 PFD-CD did not significantly change the content of GSTP1 but produced an increase in its mRNA level (+20%), while it decreased the activities of both CAT (-66%) and GSTs (-26%). After 3 PFD-CD, liver protein carbonylation and lipid peroxidation were increased by +55% and +95%, respectively. In serum, 3 PFD-CD increased the activities of both SGOT (+30%) and SGPT (+61%). In addition, 3 PFD-CD showed a histological pattern characteristic of hepatic damage. All together, these data suggest that frequent dietary amino acid deprivation causes hepatic metabolic and ultrastructural changes in a fashion similar to precancerous or cancerous conditions.
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Affiliation(s)
- Veronica J Caballero
- Instituto de Investigaciones Biológicas, Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Mar del Plata-CONICET, Funes 3250 4º Nivel, CP 7600, Mar del Plata, Argentina
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6
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Abstract
The last 10 years have seen a significant expansion in the scope of attempts to manipulate the growth of animals (Buttery, Lindsay and Haynes, 1986). The expansion of interest has been driven by a number of factors, both economic and theoretical. At the economic level the need to develop energetically and economically efficient strategies of animal production has been coupled with a renewed awareness of the implications for human health of excessive intakes of saturated fats. Emphasis then has switched from the maximization of weight gain as an end in itself towards a need to promote protein deposition at any given intake and, at the same time, to reduce the fat content of meat and meat products. These twin objectives might be achieved by one of three strategies: the promotion of protein deposition alone, because at any given rate of weight gain this will tend to minimize the rate of fat deposition (the so-called repartitioning effect); the reduction of fat gain (an approach that has received particularly close attention by those concerned primarily with human obesity); or ideally the simultaneous promotion of protein accretion and depression of that of fat.
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7
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Oxidative stress in mouse liver caused by dietary amino acid deprivation: protective effect of methionine. J Physiol Biochem 2010; 66:93-103. [PMID: 20577846 DOI: 10.1007/s13105-010-0014-x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2009] [Accepted: 03/30/2010] [Indexed: 01/24/2023]
Abstract
The aim of this work was to evaluate the effects of a diet depleted of amino acids (protein-free diet, or PFD), as well as the supplementation with methionine (PFD+Met), on the antioxidant status of the female mouse liver. With this purpose, cytosolic protein spots from two-dimensional non-equilibrium pH gel electrophoresis were identified by several procedures, such as mass spectrometry, Western blot, gel matching and enzymatic activity. PFD decreased the contents of catalase (CAT), peroxiredoxin I (Prx-I), and glutathione peroxidase (GPx) by 67%, 37% and 45%, respectively. Gene expression analyses showed that PFD caused a decrease in CAT (-20%) and GPx (-30%) mRNA levels but did not change that of Prx-I. It was also found that, when compared to a normal diet, PFD increased the liver contents of both reactive oxygen species (+50%) and oxidized protein (+88%) and decreased that of glutathione (-45%). Supplementation of PFD with Met prevented these latter effects to varying degrees, whereas CAT, Prx-I and GPx mRNA levels resulted unmodified. Present results suggest that dietary amino acid deprivation deranges the liver antioxidant defences, and this can be, in part, overcome by supplementation with Met.
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9
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Mortimore GE, Schworer CM. Application of liver perfusion as an in vitro model in studies of intracellular protein degradation. CIBA FOUNDATION SYMPOSIUM 2008:281-305. [PMID: 399892 DOI: 10.1002/9780470720585.ch17] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Amino acids appear to be prime regulators of autophagy and proteolysis in liver. They both attain a maximum rapidly when livers from fed rats are perfused in the single-pass mode without amino acids and are suppressed to basal levels by amino acid additions. The fact that their greatest responsiveness to amino acids occurs slightly below normal plasma levels suggests that these cellular processes could play a role in regulating plasma amino acid concentrations in vivo. Autophagy and proteolysis are also inhibited by insulin and stimulated by glucagon. In the latter instance the hormonal action is not direct but mediated indirectly by depletion of intracellular glutamine, probably as a consequence of enhanced gluconeogenesis. Close correlations among (1) rates of intracellular proteolysis, (2) the aggregate volume of lysosomal elements, and (3) estimates of degradable protein internalized within lysosomes indicate that lysosomal function can explain total intracellular protein degradation (with the possible exception of rapidly turning over fractions) over the full range of proteolysis from maximum down to and including the basal state. Since ratios of degradable intralysosomal protein to corresponding rates of proteolysis in intact liver are constant over this range, protein internalization may be the rate-limiting step in lysosomal proteolysis.
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Ronchi VP, Conde RD, Guillemot JC, Sanllorenti PM. The mouse liver content of carbonic anhydrase III and glutathione S-tranferases A3 and P1 depend on dietary supply of methionine and cysteine. Int J Biochem Cell Biol 2005; 36:1993-2004. [PMID: 15203113 DOI: 10.1016/j.biocel.2004.02.019] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2003] [Revised: 02/20/2004] [Accepted: 02/25/2004] [Indexed: 11/23/2022]
Abstract
The contents of glutathione S-transferase (GST) subunits, carbonic anhydrase III (CAIII), glyceraldehyde-3-phosphate dehydrogenase (GAPDH) and a 230 kDa protein are affected by protein deprivation in mouse liver. In order to know if particular amino acids control these contents, the effects of feeding for 5 days with diets containing different amino acids were examined. After an exploration using SDS-PAGE analysis, the action of selected diets was further examined by distinct techniques. The 230 kDa protein was identified as fatty acid synthase (FAS) by both mass spectrometry and amino acid sequence analyses. Dietary tests showed that: (1) a protein-free diet (PFD) increased the content of glutathione S-transferases P1 and M1, and glyceraldehyde-3-phosphate dehydrogenase, while the content of glutathione S-transferase A3, fatty acid synthase and carbonic anhydrase III decreased; (2) a protein-free diet having either methionine or cysteine preserved the normal contents of glutathione S-transferases P1, A3, M1 and carbonic anydrase III; (3) a protein-free diet having threonine preserved partially the normal contents of glutathione S-transferases P1, A3, M1 and carbonic anhydrase III; (4) a protein-free diet having methionine, threonine and cysteine prevented in part the loss of fatty acid synthase; and (5) the glyceraldehyde-3-phosphate dehydrogenase content was controlled by increased carbohydrate level and/or by lower amino acid content of diets, but not by any specific amino acid. These data indicate that methionine and cysteine exert a main role on the control of liver glutathione S-transferases A3 and P1, and carbonic anhydrase III. Thus, they emerge necessary to prevent unsafe alterations of liver metabolism caused by protein deprivation.
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Affiliation(s)
- Virginia Paola Ronchi
- Facultad de Ciencias Exactas y Naturales, Instituto de Investigaciones Biológicas, Universidad Nacional de Mar del Plata, C.C. 1245, B7600GTQ Mar del Plata, Argentina.
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11
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12
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Sanllorenti PM, Rosenfeld J, Ronchi VP, Ferrara P, Conde RD. Two dimensional non equilibrium pH gel electrophoresis mapping of cytosolic protein changes caused by dietary protein depletion in mouse liver. Mol Cell Biochem 2001; 220:49-56. [PMID: 11451382 DOI: 10.1023/a:1010853719232] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Two-dimensional non-equilibrium pH gel electrophoresis (2D-NEPHGE) analysis was used to evaluate the effects of dietary protein depletion on the protein composition of mouse liver cytosol. Analysing the cytosol from both normal and protein depleted liver, the position in gels of more than three hundred protein spots was determined. After 5 days of protein depletion, about 20% of the spots either increased or decreased more than 2 fold. Five spots of glyceraldehyde-3-phosphate dehydrogenase (GAPDH) were recognised by specific antibodies. The glutathione S-transferase (GSTs) subunits Ybl, Yc and Yf were identified by the simultaneous analysis of both glutathione-binding cytosolic proteins and the corresponding standards. As estimated by internal optical density (IOD) of spots, the changes caused by protein depletion in GAPDH and GST subunit contents were similar to those obtained by other methods. By means of mass spectrometric analysis of tryptic peptides generated from spots and/or comparison of two-dimensional gel electrophoretic patterns, carbonic anhydrase III (CAIII), Cu, Zn superoxide dismutase (CuZnSOD) and a cytochrome P450 cytosolic protein (cyt P450) were identified. These three proteins, as well as GSTs, are related with intracellular detoxification and free radical scavenging systems. Their contents were regulated by dietary protein restriction in a manner indicative of diminished liver defence against oxidising agents.
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Affiliation(s)
- P M Sanllorenti
- Instituto de Investigaciones Biológicas, Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Mar del Plata, Argentina
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Peragón J, Barroso JB, García-Salguero L, de la Higuera M, Lupiáñez JA. Dietary alterations in protein, carbohydrates and fat increase liver protein-turnover rate and decrease overall growth rate in the rainbow trout (Oncorhynchus mykiss). Mol Cell Biochem 2000; 209:97-104. [PMID: 10942206 DOI: 10.1023/a:1007130906365] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
We have determined the protein-turnover rates and nucleic-acid concentrations in the liver of trout (Oncorhynchus mykiss) fed on two different isocaloric diets: low-protein/high-fat and non-carbohydrate/high-fat. Compared to controls, the partial replacement of protein with fat significantly decreased the protein accumulation rate and protein-retention efficiency in the liver whilst increasing the fractional protein-synthesis and protein-degradation rates as well as protein-synthesis efficiency. The complete replacement of carbohydrates with fat significantly lowered the protein-accumulation rate and protein-retention efficiency, but enhanced both the protein-synthesis and protein-degradation rates as well as protein-synthesis capacity. The protein:DNA and RNA:DNA ratios decreased considerably on both diets. Total DNA decreased in fish on a low-protein/high-fat diet but did not change in those on a non-carbohydrate/high-fat diet. The absolute protein-synthesis rate registered no significant change under any of the nutritional conditions. Both the experimental diets did however raise the fractional protein-synthesis rate significantly, due to enhanced protein-synthesis efficiency when protein was partially replaced with fat and to enhanced protein-synthesis capacity when carbohydrates were completely replaced with fat. Our results show the capacity of the liver to adapt its turnover rates and conform to different nutritional conditions. They also point to the possibility of controlling fish growth by dietary means.
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Affiliation(s)
- J Peragón
- Department of Experimental Biology, Biochemistry and Molecular Biology Section, Faculty of Experimental Sciences, University of Jaen, Spain
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García-Mata R, Conde RD, Sanllorenti PM. Contribution of breakdown in the regulation of mouse liver glutathione S-transferase subunits during protein depletion and re-feeding. BIOCHIMICA ET BIOPHYSICA ACTA 1998; 1448:46-50. [PMID: 9824665 DOI: 10.1016/s0167-4889(98)00117-7] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The in vivo radioactivity decay of glutathione S-transferase (GST) was observed in livers of normal-fed (N), protein-depleted (D), and re-fed mice (R), labelled with [35S]methionine. Half-lives in days at N, D and R, respectively, were: total GST, 1.7, 1.4, 4.3; Yb1-subunit, 2.0, 1.8, 3.3; Yc-subunit, 2.4, 1.0, 4.2; Yf-subunit, 1. 1, 2.1, 5.0. These findings, together with the fact that the proportions of GST-subunits depend on dietary protein, show that breakdown contributes differentially to control the content of each GST subunit. Data also indicate that GSTs are long-life proteins.
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Affiliation(s)
- R García-Mata
- Instituto de Investigaciones Biologicas, Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Mar del Plata, cc 1245, 7600 Mar Del Plata, Argentina
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15
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Scornik OA, Howell SK, Botbol V. Protein depletion and replenishment in mice: different roles of muscle and liver. THE AMERICAN JOURNAL OF PHYSIOLOGY 1997; 273:E1158-67. [PMID: 9435532 DOI: 10.1152/ajpendo.1997.273.6.e1158] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Fully grown male CD-1 mice, fed a protein-free diet for 3 days, received 1 g of starch with or without 300 mg casein by intragastric intubation. We surveyed the acute effects of these nutrients on protein synthesis in all tissues (by extrapolating to infinity the incorporation of radioactive leucine after its injection in massive doses) and protein degradation in skeletal muscle and liver (by the accumulation of bestatin-induced peptide intermediates). Muscle proteolysis was the major source of N during depletion. Compared with postabsorptive animals, starch suppressed muscle protein loss (synthesis +21%, degradation -24%, P < 0.01) and stimulated hepatic proteolysis (degradation +28%, P < 0.01). Addition of casein to the starch was anabolic in liver (synthesis +41%, degradation -33%, P < 0.01), gastrointestinal tract, pancreas, and skin (synthesis +38, +69 and +38%, respectively, P < 0.01) but had no effect on muscle. Protein turnover proved uniquely sensitive to the dietary supply of carbohydrates in muscle and to the endogenous or exogenous supply of amino acids in liver.
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Affiliation(s)
- O A Scornik
- Department of Biochemistry, Dartmouth Medical School, Hanover, New Hampshire 03755-3844, USA
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16
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Barle H, Nyberg B, Andersson K, Essén P, McNurlan MA, Wernerman J, Garlick PJ. The effects of short-term parenteral nutrition on human liver protein and amino acid metabolism during laparoscopic surgery. JPEN J Parenter Enteral Nutr 1997; 21:330-5. [PMID: 9406129 DOI: 10.1177/0148607197021006330] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
BACKGROUND This study was undertaken to elucidate the specific effects of short-term artificial nutrition on human liver protein metabolism. METHODS Thirty patients undergoing elective laparoscopic cholecystectomy were studied: a control group (n = 16) and a group that received total parenteral nutrition (TPN; n = 14). The nutrition consisted of a balanced i.v. solution of nutrients (17.5 nonprotein kcal/kg body wt, 50% fat, 50% carbohydrates, and 0.1 gN/kg) that was discontinued when the investigation was finished, after a total infusion time of 8.6 +/- 1.0 hours. A liver biopsy specimen was taken as soon as possible after surgery was started, for the determination of the free hepatic amino acid concentrations. In 16 of the patients, L[2H5]phenylalanine was given by i.v. to determine the fractional synthesis rate of total liver protein in a second liver biopsy specimen taken approximately 30 minutes later. RESULTS The fractional synthesis rate of total liver protein was 15.2% +/- 4.7%/d in the TPN group (n = 7), which was not different from that of the control group (17.7% +/- 3.8%/d, n = 9). However, the free hepatic concentrations of alanine (p < .05) and the essential amino acids increased (p < .001) in the TPN group, whereas the total hepatic amino acid concentrations were comparable between the groups. CONCLUSION Thus short-term TPN induced specific changes of the free hepatic amino acid concentrations, whereas total liver protein synthesis remained unaffected by the nutrition.
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Affiliation(s)
- H Barle
- Department of Anesthesiology and Intensive Care, Huddinge University Hospital, Karolinska Institute, Stockholm
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García-Mata R, Capdevielle J, Guillemot JC, Ferrara P, Conde RD, Sanllorenti PM. Protein depletion and refeeding change the proportion of mouse liver glutathione S-transferase subunits. BIOCHIMICA ET BIOPHYSICA ACTA 1997; 1357:272-80. [PMID: 9268051 DOI: 10.1016/s0167-4889(97)00036-0] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
The effect of protein depletion followed by refeeding with a normal diet on the content of mouse liver cytosolic proteins was studied. By peptide-mass fingerprinting and N-terminal sequencing, three polypeptides whose contents changed with dietary protein level were identified as glutathione S-transferases (GST) Yb1, Yc and Yf subunits. Five days of depletion caused the increase of Yb1 and Yf (21.6% and 78.5%, respectively) and the decrease of Yc (31.2%). After two days of refeeding, Yb1 and Yc were practically restored, while the neoplastic marker Yf remained higher (63.4%). None of the nutritional conditions tested induced new GSTs. While protein depletion-refeeding altered the ratios between the constitutive GST subunits, total liver GST content and activity were unaffected by depletion and slightly increased by refeeding. The increased amounts of Yb1 and Yf, and the maintenance of total GST content, indicate that during protein depletion, the GST subunits levels are controlled by mechanisms different from the majority of cytosolic proteins.
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Affiliation(s)
- R García-Mata
- Instituto de Investigaciones Biológicas, Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Mar del Plata, Argentina
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18
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Gerlach JC, Fuchs M, Smith MD, Bornemann R, Encke J, Neuhaus P, Riedel E. Is a clinical application of hybrid liver support systems limited by an initial disorder in cellular amino acid and alpha-keto acid metabolism, rather than by later gradual loss of primary hepatocyte function? Transplantation 1996; 62:224-8. [PMID: 8755820 DOI: 10.1097/00007890-199607270-00013] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
The in-vitro amino acid (AA) and alpha-keto acid (KA) metabolism of bioreactors initially seeded with 2.5 x 10(9) pig hepatocytes was investigated with a perfusion technique. Considerable changes in the culture medium concentrations of AA and KA were measured during the first days in culture. This is indicative of dynamic cellular metabolism in the initial phase. While the concentration of pyruvate decreased starting on the first day, alpha-ketoglutarate, alpha-ketoisocaproate, alpha-ketoisovalerate, and alpha-keto-beta-methyl-n-valerate were synthesized. The long term use of hepatocyte cultures in bioreactors and thus a desirable clinical hybrid liver support therapy appears to be possible since the hepatocytes switched, after 15 days in culture, to steady-state conditions with a stable amino acid turnover featuring general AA uptake accompanied by KA release. The release of branched chain KA, in particular that of alpha-ketoisocaproate, reflects an effective transamination activity in the bioreactor system. Primary pig hepatocytes cultivated in hybrid liver support systems for therapy of acute liver failure or as devices for bridging to liver transplantation can sustain amino acid metabolism for at least 30 days in vitro. However, an initial disorder following the cell isolation that is demonstrated may limit immediate utilization of the systems prior to the reorganisation of the cells to tissue-like structures in bioreactors.
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Affiliation(s)
- J C Gerlach
- Virchow Klinikum, Chirurgische Klinik, Humboldt Universität, Berlin, Germany
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19
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Affiliation(s)
- G E Mortimore
- Department of Cellular and Molecular Physiology, Hershey Medical Center, Pennsylvania State University, Hershey 17033, USA
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20
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Garlick PJ, McNurlan MA, Essén P, Wernerman J. Measurement of tissue protein synthesis rates in vivo: a critical analysis of contrasting methods. THE AMERICAN JOURNAL OF PHYSIOLOGY 1994; 266:E287-97. [PMID: 8166249 DOI: 10.1152/ajpendo.1994.266.3.e287] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
The extension of the flooding method for measuring the rate of protein synthesis, from animal to human tissues, has led to criticism. This is based on the observation that in human muscle, unlike animal tissues, the rate of synthesis in the fasting state measured with constant infusion is lower than that obtained with the flooding technique. Moreover, incorporation of infused tracer can be enhanced with a simultaneous flood, although an inhibition of incorporation has also been reported. Explanations for these observed discrepancies are explored. Evidence from studies in human muscle both with flooding and with a nonisotopic technique have given no indication of a stimulation of protein synthesis during flooding. It is therefore concluded that the most likely explanation for the discrepancy between methods is that changes in the isotopic enrichment of the precursor amino acid, which are minimized by the flooding procedure, are not adequately accounted for with the constant infusion method.
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Affiliation(s)
- P J Garlick
- Rowett Research Institute, Bucksburn, Aberdeen, United Kingdom
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21
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Nikolić J, Bjelaković G, Kocić G. Effects of folic acid and methotrexate on arginase activity in regenerating rat liver tissue. ARCHIVES INTERNATIONALES DE PHYSIOLOGIE, DE BIOCHIMIE ET DE BIOPHYSIQUE 1993; 101:271-273. [PMID: 7508284 DOI: 10.3109/13813459309003923] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
Arginase (L-arginine-ureidohydrolase, EC 3.5.3.1) catalyses the hydrolysis of arginine to ornithine and urea. Its primary metabolic role is to remove the excess of ammonia through synthesis of urea. Ornithine, as a product of arginase reaction can be used for synthesis of polyamines. Rapid tissue growth after partial hepatectomy is accompanied by an increase in biosynthesis of polyamines. The aim of this study was to examine the importance of arginase in regenerating liver after partial hepatectomy and to investigate the influence of folic acid and methotrexate on arginase activity on this model of compensatory growth. It was established that arginase activity was significantly reduced in regenerating rat liver tissue at different time intervals after partial hepatectomy. Administration of folic acid to hepatectomized rats led to inhibition of arginase activity. Administration of methotrexate after hepatectomy increased the arginase activity.
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Affiliation(s)
- J Nikolić
- Institute of Biochemistry, Faculty of Medicine, University of Nis, Yugoslavia
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22
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Sanllorenti PM, Tardivo DB, Conde RD. Dietary level of protein regulates glyceraldehyde-3-phosphate dehydrogenase content and synthesis rate in mouse liver cytosol. Mol Cell Biochem 1992; 115:117-28. [PMID: 1448056 DOI: 10.1007/bf00230321] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
The content of liver cytosolic proteins was studied in mice subjected to protein depletion followed by refeeding with a normal diet. Depletion elicited either the accumulation or the decrease of several polypeptides, being the early increase of a M(r) 36,000 polypeptide the most pronounced change observed. The refeeding with a normal diet for 2 days caused a return of the cytosol protein composition to that of normally fed animals. The M(r) 36,000 polypeptide was identified as glyceraldehyde-3-phosphate dehydrogenase (GAPDH). Its molecular weight, the sequence of its first twenty amino acid residues, its amino acid composition and its antigenic properties were found to be similar with those of GAPDH from different mammalian cells. During the first 2 days of protein depletion, both the GAPDH polypeptide content and activity increased. Thereafter, the enzymatic activity of GAPDH decreased, whereas GAPDH protein mass decreased in a lesser extent. The accumulation of GAPDH and other particular polypeptides in the cytosols of protein depleted mice was associated with an increased synthesis. The refeeding with a normal diet caused an immediate return to the synthesis pattern of normal livers.
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Affiliation(s)
- P M Sanllorenti
- Instituto de Investigaciones Biologicas, Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Mar del Plata, Agentina
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23
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Abstract
The organochlorine compound mirex (dodecachloro-octahydro-1,3,4-metheno-2H-cyclobuta-CD- pentalene) induces an adaptive liver growth dependent on the hormonal status of the experimental animal. In the intact laboratory rat, mirex induces liver growth that is an expression of both cellular hyperplasia and hypertrophy. However, in rats subjected to adrenalectomy, mirex induces liver growth that is essentially hyperplastic. Corticosterone supplements given to rats subjected to adrenalectomy and treated with mirex restore the hypertrophic component of liver growth. Therefore it appears that the expression of the hypertrophic component of mirex-induced liver growth is corticosterone dependent. To further explore the hormonal modulation of the expression of mirex-induced adaptive liver growth, rats subjected to thyroidectomy were studied. In male rats subjected to thyroidectomy, a single oral dose of mirex (100 mg/kg body wt) increased relative liver weight (liver wt/body wt x 100) by 62% within 72-hr after mirex administration. Liver growth occurred in the absence of [3H]thymidine incorporation into liver DNA. Thus the observed liver growth was totally hypertrophic. However, in mirex-dosed rats subjected to thyroidectomy given twice-daily subcutaneous injections of thyroxine (5 mg/kg body wt), relative liver weight was increased by 204% of the control value within 72-hr after mirex administration, and there was a peak of [3H]thymidine incorporation into liver DNA 54 hr after mirex administration. These studies suggest that the expression of hyperplasia in mirex-induced adaptive liver growth is thyroxine dependent.
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Affiliation(s)
- J D Yarbrough
- Department of Biology, University of Alabama, Tuscaloosa 35487
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24
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Role of Autophagy in Hepatic Macromolecular Turnover. ACTA ACUST UNITED AC 1992. [DOI: 10.1016/s1569-2558(08)60179-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
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25
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Pérez-Sala D, Calleja TR, Parrilla R, Ayuso MS. Effect of alanine supply on hepatic protein synthesis in animals maintained on a protein free diet. Mol Cell Biochem 1991; 108:105-12. [PMID: 1779957 DOI: 10.1007/bf00233114] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
In contrast to what it is observed during starvation, animals maintained on a protein-free isocaloric diet showed an increase in the rate of hepatic peptide chain elongation as determined by measuring the ribosomal transit time in vivo. The loss of body nitrogen per se is insufficient to generate the signal(s) which arrests hepatic peptide chain elongation. This observation suggests that it is an increase in gluconeogenic demand, and not the negative nitrogen balance, which is implicated in determining reciprocal changes in the rate of protein synthesis. The rate of protein synthesis, as expressed per mg of DNA, does not change in protein deprived animals, while the RNA to DNA ratio decreased. These data also agree with a higher ribosomal efficiency at the elongation step. The animals maintained on a protein-free diet have a decreased hepatic content of protein and an increased concentration of valine, indicating an increased proteolysis. The enhanced rate of polypeptide elongation observed in animals kept on a protein-free diet was accompanied by decreases in the state of aggregation of polyribosomes and in the ability of liver extracts to form eIF-2 catalyzed ternary complexes. These observations suggest that the activity of the hepatic initiation factor in vivo may not be rate limiting. The administration of alanine in vivo to animals maintained on a protein-free diet showed a preferential effect in reaggregating polyribosomes. This action was neither accompanied by detectable effects on the rate of eIF-2 catalyzed ternary complexes formation nor by significant changes in the rate of elongation.(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- D Pérez-Sala
- Endocrine Physiology Unit, Centro de Investigaciones Biológicas, C.S.I.C., Madrid, Spain
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26
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Botbol V, Scornik OA. Measurement of instant rates of protein degradation in the livers of intact mice by the accumulation of bestatin-induced peptides. J Biol Chem 1991. [DOI: 10.1016/s0021-9258(18)52222-5] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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27
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Silva SV, Mercer JR. The effect of protein intake on the potential activity of the lysosomal vacuolar system in the cat. COMPARATIVE BIOCHEMISTRY AND PHYSIOLOGY. A, COMPARATIVE PHYSIOLOGY 1991; 98:551-8. [PMID: 1674461 DOI: 10.1016/0300-9629(91)90445-i] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
1. Experiments were conducted to examine the relationship between protein intake and protein degradation in the liver of cats. 2. The cats were fed either a low protein/high carbohydrate diet (LP) or a high protein diet devoid of carbohydrate (HP). 3. The potential proteolytic activity of the lysosomal vacuolar system in the liver was assessed by both indirect (osmotic fragility of hepatic lysosomes) and direct (stereological measurement of lysosomal volume) methods. 4. The results from both tests indicated a significantly lower autophagic activity of the lysosomal system in the LP fed animals than in the HP fed cats. 5. This suppression of lysosomal protein degradation may represent an important mechanism for the conservation of proteins by the cat when low protein diets are fed.
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Affiliation(s)
- S V Silva
- Department of Pathology, Ontario Veterinary College, University of Guelph, Canada
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28
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Amino acid control of proteolysis in perfused livers of synchronously fed rats. Mechanism and specificity of alanine co-regulation. J Biol Chem 1991. [DOI: 10.1016/s0021-9258(17)35277-8] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
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29
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McNurlan MA, Garlick PJ. Influence of nutrient intake on protein turnover. DIABETES/METABOLISM REVIEWS 1989; 5:165-89. [PMID: 2647434 DOI: 10.1002/dmr.5610050206] [Citation(s) in RCA: 57] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Affiliation(s)
- M A McNurlan
- Rowett Research Institute, Bucksburn, Aberdeen, Scotland, United Kingdom
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30
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Mortimore GE, Pösö AR, Lardeux BR. Mechanism and regulation of protein degradation in liver. DIABETES/METABOLISM REVIEWS 1989; 5:49-70. [PMID: 2649336 DOI: 10.1002/dmr.5610050105] [Citation(s) in RCA: 160] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
The degradation of intracellular protein and other cytoplasmic macromolecules in liver is an ongoing process that regulates cytoplasmic mass and provides amino acids for energy and other metabolic uses early in starvation. Cellular proteins are conveniently divided into two general classes according to readily discernable differences in average rates of turnover. A short-lived class, having a half-life of approximately 10 min, comprises about 0.6% of total protein. Its degradation is not physiologically controlled, and the mechanism is probably nonlysosomal in nature. The second or long-lived group, with an average half-life 250 times greater, constitutes more than 99% of the cell's protein. By contrast, its breakdown is strongly regulated, and the site of catabolism is believed to be the vacuolar-lysosomal system. Cytoplasmic sequestration by lysosomes can be divided into two categories; macro- and microautophagy. The first is induced by amino acid and/or insulin deprivation. Amino acids are considered to be primary regulators, since they can control this process over the full range of induced proteolysis in the absence of hormones. Glucagon, cyclic AMP, and beta-agonists also stimulate macroautophagy in hepatocytes but have opposite effects in myocytes. Micrautophagy differs from the former in that the cytoplasmic "bite" is smaller and the uptake process is not acutely regulated. However, the latter does decrease during starvation in parallel with basal proteolysis, effects that might be linked to the loss of endoplasmic reticulum. The primary control of macroautophagy is accomplished through a small group of direct regulators (Leu, Tyr/Phe, Gln, Pro, Met, His, and Trp) and a specific coregulatory action of alanine. As a group, regulatory amino acids produce direct inhibitory responses in the perfused rat liver that are identical to those of the complete amino acid mixture at 0.5x and 4x (times) normal plasma concentrations. However, they lose effectiveness almost completely within a narrow zone centered at normal levels, a loss that can be abolished by the addition of alanine at its normal plasma concentration (0.5 mM). At this level, alanine does not inhibit directly. Interestingly, this zonal loss is also eliminated by insulin. Glucagon, though, specifically blocks the initial inhibition evoked by 0.5x amino acid mixtures and thus induces maximal rates of protein degradation at normal amino acid concentrations.(ABSTRACT TRUNCATED AT 400 WORDS)
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Affiliation(s)
- G E Mortimore
- Department of Physiology, College of Medicine, Pennsylvania State University, Hershey 17033
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31
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Lardeux BR, Heydrick SJ, Mortimore GE. Rates of rat liver RNA degradation in vivo as determined from cytidine release during brief cyclic perfusion in situ. Biochem J 1988; 252:363-7. [PMID: 2458100 PMCID: PMC1149153 DOI: 10.1042/bj2520363] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
The breakdown of RNA and of long-lived proteins in rat liver is believed to occur largely within the lysosomal-vacuolar system. Both processes are induced by amino acid lack and suppressed by insulin, and in all circumstances a consistent lag of 15-20 min was observed between the introduction of a physiological regulator and onset of the degradative response. This lag has allowed us to determine rates of liver RNA degradation in vivo during brief cyclic perfusions, as was done previously for long-lived-protein breakdown [Hutson & Mortimore (1982) J. Biol. Chem. 257, 9548-9554]. Degradation was measured from the release of [14C]cytidine in livers of rats previously labelled in vivo with [6-14C]orotic acid. Release was linear and unaffected by physiological regulators between 2 and 12 min of perfusion. In contrast with protein breakdown, no short-lived component was observed. In animals trained to feed between 16:00 and 20:00 h, the content of liver RNA fell at an average rate of 0.26 mg/h per 100 g initial body wt. between 07:00 and 16:00 h, a loss that was within 9% of that predicted from the net release (total release minus reutilization) of cytidine in vivo. In addition, the total rate of RNA degradation determined at the end of the meal was only 12% of that at the start of the post-absorptive period 14 h later (2.1 versus 17.1%/day). This finding is fully consistent with a lysosomal mechanism for RNA degradation, since autophagy is strongly suppressed by food intake. This approach provides a comparatively simple means of approximating moment-to-moment rates of RNA degradation in the rat liver in vivo.
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Affiliation(s)
- B R Lardeux
- Department of Physiology, Milton S. Hershey Medical Center, Pennsylvania State University, Hershey 17033
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32
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Mortimore GE, Lardeux BR, Adams CE. Regulation of microautophagy and basal protein turnover in rat liver. Effects of short-term starvation. J Biol Chem 1988. [DOI: 10.1016/s0021-9258(18)69235-x] [Citation(s) in RCA: 100] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
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33
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34
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Kwiatkowska-Patzer B, Zalewska T. Effect of propranolol upon protein and proteolytic synthesis activity in hypertrophic myocardium. Basic Res Cardiol 1988; 83:43-7. [PMID: 2967691 DOI: 10.1007/bf01907103] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
The aim of the study was to investigate the effect of propranolol upon protein synthesis and degradation processes in cell-free subfractions of rat myocardium in experimental cardiac hypertrophy induced by aortic stenosis. It was found that hypertrophy stimulates incorporation of 3H-amino acids by the postmitochondrial supernatant (PMS) by 17 +/- 4% (mean +/- SE). Propranolol 10 6M inhibited protein synthesis in the control and experimental groups by 37 +/- 5% and 34 +/- 7%, respectively. At a concentration of 5 X 10 6M, propranolol-induced inhibition in each group was 74 +/- 4% and 58 +/- 5%, respectively. The activity of neutral proteases in PMS of hypertrophic hearts increased up to 255 +/- 29 IU in comparison to 154 +/- 10 IU in controls; in the cytosol it was unchanged. Propranolol had no effect upon the activity of proteases in both fractions. Activity of calcium-activated neutral proteases (CANP) remained at the same level in control and hypertrophic hearts and was unaffected by propranolol.
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35
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Abstract
Protein synthesis and degradation are particularly sensitive to malnutrition and catabolic states. Intracellular protein degradation is determined by the conformation, molecular weight, isoelectric point, and carbohydrate content of the proteins. ATP-stimulated endoproteases appear to catalyse the rate-limiting steps. In the liver, proteolysis is reduced by amino acids and/or insulin, whereas glucagon stimulates protein degradation, probably due to depletion of intracellular gluconeogenic amino acids. In the muscle, protein degradation is promoted by interleukin-1 and inhibited by Ep-475, which specifically inactivates cathepsin B,H, and L. Myofibrillar alkaline proteinase activity increases postoperatively and in patients suffering from malignant tumors, whereas normal proteinase values were observed in these patients following total parenteral nutrition. Increased alkaline proteinase activity is also observed in diabetes mellitus and is normalized by insulin. Extracellular proteolysis has been reported in patients with hypercatabolic acute renal failure and in patients with sepsis or acute pancreatitis. Plasma fractions obtained from hypercatabolic patients with postoperative acute renal failure were proteolytic. Plasma proteinase activity decreases during hemodialysis due to elimination of a metallo-proteinase. Plasma alpha 2-macroglobulin decreases in patients with acute renal failure and also during acute pancreatitis. Proteolytic degradation of parathyroid hormone by sera obtained from patients with acute pancreatitis has been observed. Also, there is a decrease of high molecular weight kininogen during experimental acute pancreatitis. Granulocyte elastase increases postoperatively, mainly in patients with sepsis. Sepsis also causes increased proteolytic activity in the urine. In conclusion, intracellular protein degradation can supply important precursors for hepatic and renal gluconeogenesis during malnutrition.(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- W H Hörl
- Department of Medicine, University of Freiburg, FRG
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36
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Merry BJ, Holehan AM, Lewis SE, Goldspink DF. The effects of ageing and chronic dietary restriction on in vivo hepatic protein synthesis in the rat. Mech Ageing Dev 1987; 39:189-99. [PMID: 2442570 DOI: 10.1016/0047-6374(87)90008-x] [Citation(s) in RCA: 33] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Hepatic growth and protein synthesis in vivo was studied with age in ad libitum-fed and dietary restricted rats in which the mean and maximum lifespan was significantly extended. Livers from underfed rats showed significantly lower DNA, RNA and protein contents, and total protein synthesis. The fractional rate of synthesis although initially depressed by restricted feeding, showed no consistent trend with age when compared with control values. The lower fractional rate of synthesis observed in livers from dietary restricted rats at 7 weeks of age is attributable to a significant decrease in ribosomal capacity, with no effect on ribosomal activity being evident. Liver tissue from rats fed ad libitum demonstrated a progressive loss of translational efficiency with age which was delayed by chronic dietary restriction.
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37
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Shroyer KR, Nakane PK. Immunohistochemical localization of albumin and in situ hybridization of albumin mRNA. Cell Biochem Funct 1987; 5:195-210. [PMID: 3301049 DOI: 10.1002/cbf.290050307] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Hepatocytes actively involved in albumin synthesis were identified by immunohistochemical method. In sections of perioidate-lysine-2 per cent (w/v) paraformaldehyde fixed normal rat liver, albumin was detected in all hepatocytes. At the ultrastructural level, albumin was localized in the rough endoplasmic reticulum and in Golgi complexes located near the nucleus in only a small subpopulation of hepatocytes, while all other hepatocytes contained albumin only in Golgi complexes located near the bile canaliculi. Stimulation of albumin synthesis by puromycin aminonucleoside-induced nephrosis resulted in an altered intracellular distribution of albumin at the light microscopic level. When examined at the ultrastructural level, albumin was localized in the rough endoplasmic reticulum as well as in Golgi complexes located near the nucleus in nearly all these hepatocytes. Hepatocytes with the potential to synthesize albumin were identified by in situ hybridization of albumin mRNA. In sections of 0.1 per cent (v/v) glutaraldehyde perfusion fixed normal rat liver, albumin mRNA was detected in the cytoplasm of only a few hepatocytes scattered throughout the lobule. Following stimulation of albumin synthesis by the induction of nephrosis, albumin mRNA was detected in the cytoplasm of the hepatocytes. The source of albumin in those hepatocytes which lacked albumin mRNA was identified in analbuminemic rats injected with rat albumin. At 6 h post injection, the light microscopic distribution of albumin in the liver of these animals was virtually indistinguishable from that in normal rat liver. At the ultrastructural level, injected albumin was localized in lysosomes and in Golgi complexes located near the bile canaliculi.
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38
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Iapalucci-Espinoza S, Haim-Muchnik L, Franze-Fernández MT. Transcription of liver ribosomal RNA: differential effect of 5-fluorouracil depending on the nutritional state of mice. BIOCHEMICAL MEDICINE AND METABOLIC BIOLOGY 1987; 37:287-94. [PMID: 3606890 DOI: 10.1016/0885-4505(87)90039-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
The effect of 5-fluorouracil (5-FUra) on RNA transcription in mice liver cells was studied using animals exposed to different nutritional conditions as a model of normal, nondividing cells. There are two levels of rRNA transcription in mouse liver: a basal level found in mice fed on a complete diet (control mice) and a higher level, two- to three-fold increased over the basal, found in mice fed on a protein-depleting diet for about 3 days and refed on a complete diet for at least 5 hr (refed mice). The rRNA transcription was measured as the activity of RNA polymerase I in isolated liver nuclei. It was found that the intraperitoneal administration of 5-FUra (30 mg/kg body wt) to refed mice rapidly decreases the higher level of rRNA transcription towards the basal level. This is accomplished through a decrease of the initiation frequency of rRNA chains by RNA polymerase I. 5-FUra however, does not affect the basal level of rRNA transcription in liver from mice fed on a complete diet. Under this condition the drug does not affect the initiation frequency of rRNA chains. The effect of 5-FUra on rRNA transcription in refed mice is not mediated by an inhibition of protein synthesis.
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39
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Tessitore L, Bonelli G, Baccino FM. Early development of protein metabolic perturbations in the liver and skeletal muscle of tumour-bearing rats. A model system for cancer cachexia. Biochem J 1987; 241:153-9. [PMID: 3566707 PMCID: PMC1147537 DOI: 10.1042/bj2410153] [Citation(s) in RCA: 115] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
In rats into which a fast-growing ascites hepatoma (Yoshida AH-130) had been transplanted, tumour growth elicited a marked loss of body weight until the animal's death in about 2 weeks. Overall tissue protein metabolism was simultaneously studied in vivo in the gastrocnemius muscle and liver after labelling with [14C]bicarbonate. Early and progressive atrophy developed in the gastrocnemius muscle, the underlying metabolic imbalance being expressed by an elevation in the apparent protein-degradation rate, with no changes in the apparent synthesis rate. A transient hyperplastic response preceded waste in the liver, both states being associated with alterations in protein-degradation rate: an initial decrease during liver growth, then an acceleration as liver regressed. Protein-synthesis rates, virtually unchanged during liver growth, were elevated in the subsequent phase, although not sufficient to balance the enhanced breakdown. Thus, in the tumour host tissues examined, altered states of protein turnover appeared to result mostly from changes in rates of protein breakdown. In sharp contrast with the negative protein balance in the host, the ascites hepatoma cells had the ability to grow or at least, in advanced stages, to maintain a stationary state.
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40
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Abstract
Body proteins in cats were prelabelled with [14C]valine, and protein degradation was studied in isolated hepatocytes. Amino acids appeared to have a direct inhibitory effect on protein degradation, but the effects were generally smaller than those previously shown in the rat. The amino acid control of protein degradation in the cat differs from that in the rat, as shown by the lack of effects of glutamine, asparagine, arginine or methionine in cat hepatocytes. This may be related to the unique features of protein metabolism of this species. NH4Cl, leupeptin and amino acids, which suppress lysosomal protein degradation by different mechanisms, caused less than 30% inhibition of protein degradation when used at the optimum concentrations reported for the rat. The ability of the lysosomal system to respond to nutritional deprivation is apparently lower in the cat than in the rat.
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41
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Müller J, Pfeifer U, Dämmrich J. Inhibited autophagic degradation during ACTH-stimulated growth of rat adrenal zona fasciculata. VIRCHOWS ARCHIV. B, CELL PATHOLOGY INCLUDING MOLECULAR PATHOLOGY 1986; 52:429-41. [PMID: 2883765 DOI: 10.1007/bf02889983] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Autophagic vacuoles (AVs) in adrenal parenchymal cells of the outer part of the zona fasciculata were investigated by means of electron microscopic morphometry in 40 adult male Sprague Dawley rats. Four test groups and four control groups received twice daily subcutaneous injections of ACTH (12.5 U/kg body weight) or physiological saline, respectively, for 3, 6, 9 and 12 days. At 12 days the total dry weight of the adrenals was increased in ACTH-treated animals from 17.2 to 71.0 mg (about fourfold) and the average volume of zona fasciculata cells from 1,500 to 5,100 microns3 (about threefold). The relatively larger increase in total mass reflects mitotic activity in the growing adrenal tissue. The calculated growth rate of total tissue expressed as the percentage increase in dry weight per day was 12% at day 3 and decreased to 4.6% at day 12 of ACTH stimulation. During the time interval investigated the cytoplasmic volume fraction of autophagic vacuoles was significantly reduced from 10 X 10(-5) in controls to 1 X 10(-5) in ACTH-treated animals (p less than 0.001). Assuming a half-life for AVs of 7.9 min (Papadopoulos and Pfeifer 1986), autophagic degradation of cytoplasm can be calculated as 1.3%/day in controls, but only 0.15%/day in ACTH-treated animals. Thus growth of 1.15%/day can be attributed to inhibition of autophagic degradation. Although this is only part of total growth, it is evident from the present results that anticatabolic growth induction is utilized nearly to its maximum in adrenocortical fasciculata cells under the influence of ACTH.
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Berger JJ, Dice JF. Proteolysis in cultured cells during prolonged serum deprivation and replacement. THE AMERICAN JOURNAL OF PHYSIOLOGY 1986; 251:C748-53. [PMID: 3535530 DOI: 10.1152/ajpcell.1986.251.5.c748] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Cells in culture show a series of changes in intracellular protein degradation in response to serum deprivation and replacement that are similar to alterations in degradation in tissues of starved and refed animals. Rates of intracellular protein degradation are increased in confluent cultures of IMR-90 human diploid fibroblasts when deprived of serum, but this enhanced proteolysis is transient. By 24-48 h, rates of protein degradation decline to values comparable to or below those for cells incubated in the presence of serum. Longer serum deprivation leads to further reductions in proteolysis. The reduced proteolysis after long-term deprivation cannot be explained by experimental artifacts or by gradual depletion of glucocorticoids or thyroid hormones from cells. Readdition of serum to deprived cells that are still in the enhanced phase of proteolysis restores degradation rates to values comparable to those in nondeprived cells. However, in cells deprived of serum for 24-48 h or longer, readdition of serum to the medium results in a marked reduction in proteolysis to rates below those observed in nondeprived cells. These responses of cultured cells to long-term serum deprivation and readdition may be of considerable physiological importance in that the proteolytic responses of tissues in starved and refed animals may be at least partially due to mechanisms operating at the cellular level.
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Gooderham NJ, Mannering GJ. Depression of cytochrome P-450 and alterations of protein metabolism in mice treated with the interferon inducer polyriboinosinic acid X polyribocytidylic acid. Arch Biochem Biophys 1986; 250:418-25. [PMID: 2430524 DOI: 10.1016/0003-9861(86)90744-7] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Treatment of mice with the interferon inducer polyriboinosinic acid X polyribocytidylic acid [poly(IC)] results in the depression of several hepatic proteins. In this study we examined synthesis and degradation of the proteins of liver cell organelles in mice treated with poly(IC). Effects on synthesis were determined by using [14C]- and L-[3H]leucine incorporation into control and poly(IC)-treated mice, respectively. At selected times after poly(IC) treatment the 3H/14C ratio was established for preparations of nuclei, mitochondria, lysosomes, smooth endoplasmic reticulum, rough endoplasmic reticulum, and 105,000g supernatant (cytosol). Time-dependent alterations in de novo protein synthesis were greatest in lysosomal and rough endoplasmic reticular fractions; both were depressed 9 h after treatment. The effects of poly(IC) on protein degradation were determined with [14C]bicarbonate. Poly(IC) treatment decreased the time required for disappearance of 50% of 14C-labeled protein (t1/2) of smooth and rough endoplasmic reticula. Examination of endoplasmic reticulum marker enzymes showed depression of cytochromes P-450 and b5 from 9 h onward after poly(IC) administration. Tyrosine aminotransferase activity was elevated 6 h after treatment with poly(IC), and then depressed after 9 h. The other organelle marker enzymes were not affected significantly. We conclude that poly(IC) decreases the content of proteins of the hepatic endoplasmic reticulum, including certain cytochrome P-450 isozymes, by decreasing rates of protein synthesis and increasing rates of protein degradation.
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Ashford AJ, Pain VM. Insulin stimulation of growth in diabetic rats. Synthesis and degradation of ribosomes and total tissue protein in skeletal muscle and heart. J Biol Chem 1986. [DOI: 10.1016/s0021-9258(17)35622-3] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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James J, Bosch KS, Fronik GM, Houtkooper JM. Naphthol-yellow-S protein content of individual rat hepatocytes as related to food intake and short-term starvation. Cell Tissue Res 1986; 243:165-9. [PMID: 3943120 DOI: 10.1007/bf00221865] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
With regard to the protein content, as analysed cytophotometrically, of hepatocytes from rats kept under a 12L 12D photoperiod (photophase 7:00-19:00), the following facts have been established: 1) Hepatocytes of different classes of ploidy all demonstrate, more or less equally, daily variations in protein content and also its reduction after 24-h fasting. 2) With computer analysis of data obtained at eight time points during a period of 24 h, a sinusoidal curve of the protein content of individual mononuclear tetraploid hepatocytes throughout the day could be demonstrated with a maximum at 6:20 and a minimum at 18:20. 3) Animals, fed with meals via a dispensing machine from 23:00 to 24:00 only, show a similar sinusoidal curve but with higher amplitude, and a virtually identical mean value as those fed ad libitum. The maximum was found at 10:40, revealing a time lag of 12 h after food intake, the minimum at 22:40. 4) Trained animals deprived of food during the standardized feeding time revealed a moderate reduction of their hepatocyte protein content in the first 6 h, then a 6-h period with a steep fall followed by a slower reduction. After 24 h, the mean hepatocyte protein mass had decreased to 72% of that at the commencement of fasting at 23:00.
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Mortimore GE, Pösö AR. The lysosomal pathway of intracellular proteolysis in liver: regulation by amino acids. ADVANCES IN ENZYME REGULATION 1986; 25:257-76. [PMID: 3492868 DOI: 10.1016/0065-2571(86)90018-x] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
The bulk of cellular protein in hepatocytes is sequestered and degraded by two classes of autophagy, (a) an overt or macro form, and (b) microautophagy. Macroautophagy is rapidly induced by amino acid deprivation and the administration of glucagon and suppressed by amino acids and insulin. Amino acids appear to be its primary regulator since liver perfusion studies have shown that it can be inhibited almost completely and proteolysis decreased from maximal (4.5% hr) to basal rates (1.7%/hr) by 4 times normal plasma amino acid concentrations. The resulting alterations in the aggregate volume of autophagic vacuoles are associated with proportional changes in the amount of cytoplasmic protein sequestered and in rates of protein degradation. Since the apparent turnover of autophagic vacuoles is 0.087 min-1, the pools of sequestered protein at all levels of macroautophagic stimulation are sufficient to account fully for the observed rates of accelerated rate of proteolysis. Microautophagy differs from the former in that the cytoplasmic 'bite' is smaller and it is not subject to acute physiological regulation. It is, however, dramatically decreased to near zero during refeeding after prior starvation. These and other findings indicate that it is adaptively regulated, possibly as a consequence of alterations in the amount of smooth endoplasmic reticulum. The amino acid control of accelerated protein degradation appears to involve direct inhibition by a small group of amino acids (Leu, Tyr/Phe, Gln, Pro, Met, Trp, and His) and the permissive action of alanine. Of unusual interest is the fact that, whereas the inhibitory amino acid group evokes responses identical to a complete amino acid mixture at 0.5x and 4x normal amino acid concentrations, it loses its effectiveness at normal levels; similar responses have been shown for leucine alone. The loss of effectiveness at normal concentrations is abolished by the addition of 0.5 mM alanine which by itself is not directly inhibitory. No other amino acid can replace alanine. These findings suggest a novel role for alanine that could be of importance in linking energy demands to proteolysis. A hypothetical model for proteolytic regulation by leucine and the other inhibitory amino acids is presented.
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Regoeczi E, Charlwood PA, Chindemi PA. The effects of cytotropic compounds on the resialylation of human asialotransferrin type 3 in the rat. Exp Cell Res 1985; 157:495-503. [PMID: 2858398 DOI: 10.1016/0014-4827(85)90134-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Effects of chloroquine, colchicine, leupeptin, taxol and vinblastine on the resialylation and degradation of human [125I]asialotransferrin type 3 were studied in rats. An improved experimental technique was applied that permitted the quantification of resialylated ligand produced by individual animals over 3 h by using deconvolution. All three microtubule inhibitors increased the proportion of the dose undergoing resialylation by 35-39%. In addition, colchicine, and, especially, vinblastine enhanced the overall recovery of the dose as protein-bound 125I. The dose recovery was also augmented by leupeptin without any concomitant change in resialylation. Chloroquine suppressed resialylation and this effect could only be partially lifted by the administration of colchicine. The blood of colchicine-treated rats possessed no resialylating activity toward the ligand even when supplemented with additional alkaloid in vitro. The observations support the view that the respective fractions of the ligand destined for resialylation and degradation can, to a certain extent, be varied independently of each other. The effects of short-term starvation (20 h) and refeeding (4 h) on these processes are also presented.
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Abstract
Castration increased liver alcohol dehydrogenase activity and enzyme protein in male rats. The turnover of alcohol dehydrogenase determined from the decline in radioactivity present in immunoprecipitated enzyme after injection of NaH14CO3 was decreased after castration. The fractional rate of degradation (Kd) for the enzyme was 0.11 . day-1 in the castrated as compared with 0.13 . day-1 in the control animals (P less than 0.05). The fractional rate of synthesis (Ks) of the enzyme was not affected by castration, while the absolute rate of synthesis was increased slightly. This study shows that a decrease in the rate of degradation is the principal cause for the increase in liver alcohol dehydrogenase following castration.
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Mortimore GE, Surmacz CA. Liver perfusion: an in vitro technique for the study of intracellular protein turnover and its regulation in vivo. Proc Nutr Soc 1984; 43:161-77. [PMID: 6382268 DOI: 10.1079/pns19840039] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
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Laurent BC, Moldawer LL, Young VR, Bistrian BR, Blackburn GL. Whole-body leucine and muscle protein kinetics in rats fed varying protein intakes. THE AMERICAN JOURNAL OF PHYSIOLOGY 1984; 246:E444-51. [PMID: 6426316 DOI: 10.1152/ajpendo.1984.246.5.e444] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Whole-body leucine kinetics and rectus muscle synthetic rates were evaluated in postabsorptive rats fed semipurified diets that varied in the casein content. Rats were allowed to consume ad libitum a 2% casein diet or were pair-fed or ad libitum-fed 6, 20, or 40% casein diets for 14 days. After overnight starvation, rates of whole-body leucine kinetics and rectus muscle synthetic rates were determined with a 2-h constant intravenous infusion of L-[1-14C]leucine. The postabsorptive response to inadequate protein intakes included a significant reduction in the release of leucine from whole-body protein degradation as well as subsequent reutilization for protein synthesis. In contrast, dietary protein intake at levels greater than required for maximal growth were not associated with any increases in leucine incorporation into whole-body protein or muscle fractional synthetic rates. Rates of whole-body leucine oxidation based on plasma leucine specific radioactivities underestimated total oxidation by 22-27%, and this was relatively constant as the protein component of the diet was varied. In addition, the muscle acid-soluble leucine specific radioactivity was similar to the plasma alpha-ketoisocaproate enrichment, regardless of dietary protein intake.
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