Reviews |
From the Department of Histology and Molecular Cell Biology, Institute of Anatomy and Histology, University of Innsbruck, Austria.
Correspondence to Lukas A. Huber, Institute of Anatomy and Histology, Department of Histology and Molecular Cell Biology, University of Innsbruck, 6020 Innsbruck, Austria. E-mail Lukas.A.Huber{at}uibk.ac.at
Jennifer E. Van Eyk Guest Editor This Review is part of a thematic series on Proteomics, which includes the following articles:Cardiovascular Proteomics: Evolution and PotentialApplied Proteomics: Mitochondrial Proteins and Effect on FunctionOrganelle Proteomics: Implications for Subcellular Fractionation in ProteomicsProteomics in the Cardiomyopathies and Heart Failure: A Step Beyond GenomicsGlycosylation of Apolipoprotein EPosttranslational ModificationsIdentification of Novel Signaling Complexes, Modules, and Binding Partners in Cardioprotection: A FunctionalProteomic Approach
| Abstract |
|---|
|
|
|---|
Key Words: proteomics subcellular fractionation organelle
| Introduction |
|---|
|
|
|---|
The most commonly used technology for monitoring changes in the expression of complex protein mixtures is still 2D gel electrophoresis.2,3 Usually this is followed by computer analysis to reveal patterns of protein expression. Proteins of interest are then cut out from the gel one by one, enzymatically digested into fragments, and analyzed by a mass spectrometer to generate a mass spectrometric fingerprint of the proteins fragments. From this fingerprint, the likely combination of masses comprising the protein can be predicted, and this information can then be compared with the information within a genomic database to identify the corresponding DNA sequence.
Although 2D gels were invented in 1975,2,3 the technology is still tedious and difficult to apply. The crucial question is how to relate the changes in expression levels of proteins on 2D-gels to the biology of a system when we can see only a minor fraction of all the proteins present. Because of the limited resolution power of separation technologies presently applied in proteomics research, additional fractionation steps upstream of 2D gel electrophoresis and mass spectrometry are required. Therefore, proteomics research has become increasingly aware of techniques for analyzing subcellular proteomes of reduced complexity.4 Only after applying additional technologies, such as subcellular fractionation,5 affinity purification of samples,6 or zoom gels,7 which are used in 2D electrophoresis to cover narrow pH ranges and give higher resolution as well as sensitivity, could low copy number proteins have been detected.
Subcellular fractionation, allowing the separation of organelles based on their physical properties, was initially applied to separate organelles derived from rat liver.810 Subcellular fractionation consists of two major steps, disruption of the cellular organization (homogenization) and fractionation of the homogenate to separate the different populations of organelles. Such a homogenate can then be resolved by differential centrifugation into several fractions containing mainly (1) nuclei, heavy mitochondria, cytoskeletal networks, and plasma membrane; (2) light mitochondria, lysosomes, and peroxisomes; (3) Golgi apparatus, endosomes and microsomes, and endoplasmic reticulum (ER); and (4) cytosol. Each population of organelles is characterized by size, density, charge, and other properties on which the separation relies.5
However, two major problems have impeded the development of standardized and ready-to-go procedures for subcellular fractionation. First, differential subcellular compartments share similar physical properties and cofractionate at least to some extent in conventional gradients. Second, tissue culture cells are now more commonly used for fractionation, because cells can be manipulated in a manner impossible to achieve in animal-derived tissue. However, after homogenization, tissue culture cells are more difficult to fractionate than most tissues, presumably because of differences in the cytoskeletal organization. It is essential to point out that complete purification is, with few exceptions, hardly possible. However, it is still very powerful, and many laboratories began to apply traditional subcellular fractionation procedures within proteome studies.4
The objective of this review was to highlight simple but very useful subcellular fractionation techniques that can be easily combined with proteomics technologies. We will discuss how to assess the quality of such preparations and their limitations and advantages.
| How To Get Started |
|---|
|
|
|---|
First, cells are cooled down on ice and scraped gently with a soft rubber policeman into Ca2+/Mg2+-containing PBS to prevent cell breakage (Figure 1, step 1). Cells are then collected by a low-speed centrifugation step and mechanically homogenized (Figure 1, step 2). The quality of the homogenization should be assessed by morphological means; eg, by phase-contrast microscopy, it is possible to assess the extent of cellular disruption, ie, the appearance of unbroken nuclei and the absence of large aggregates11 or intact cells. Taking these precautions into consideration, one can assume that after homogenization, the nuclei are totally removed by a low-speed centrifugation step (Figure 1, step 3), together with cell debris, unbroken cells, and some larger subcellular components (Figure 2A). For additional analysis, nuclei can be purified from the pellet fraction (Figure 2B). The postnuclear supernatant (PNS) contains the cytosol and the other organelles in free suspension, which can be subsequently separated by gradient centrifugation or other techniques. Detailed experimental protocols can be found as a free download from our Web site (http://www2.uibk.ac.at/ahe/histologie-molekulare-zellbiologie/).
|
|
| Fractionation by Centrifugation |
|---|
|
|
|---|
PNS obtained in the first centrifugation step after the homogenization of cells can be additionally fractionated by different means. A very simple and rapid fractionation protocol represents high-speed sedimentation/centrifugation (100 000g), which separates the total membrane fraction from all soluble proteins (Figure 1, steps 4 and 5).12 This method is very robust and can also be used with small sample volumes in so-called tabletop ultracentrifuges or even in mini-rotors with a conventional airfuge.13 This simple protocol allows fractionation of cells into three major constituents, membranes, cytosol, and nuclei. It is suitable for the overall analysis of quantitative changes of proteins as well as for identification of their posttranslational modifications brought about by growth, differentiation, senescence, environmental changes, genetic manipulation, or other events. This analytical step is performed with already less-complex subproteomes, where rare protein species get enriched. In addition, proteins that shuttle between these three major subcellular compartments can be identified rather easily.
Alternatively, the PNS can be additionally fractionated by density gradient centrifugation (Figure 1, steps 6 and 7).14 The position of membrane particles in density gradients is determined mainly by the ratio of their lipid to protein content; eg, mitochondrial inner membranes are protein-rich and thus have a high density, whereas endosomal membranes are lipid-rich and are of low density.5,14 Other parameters that determine density include the contents of vesicles. For example, secretory low-density lipoproteins contained within Golgi vesicles render them more buoyant, whereas the protein contents of secretory granules increases their density (eg, pituitary secretory vesicles). The presence of attached components (eg, ribosomes on rough-ER membranes and clathrin on coated vesicles) also affects the density of membranes.5,14
Although differences in composition of subcellular components affect relative densities of fractions, the degree of separation obtained also depends on the nature of the gradient medium used. Although sucrose is the most commonly used gradient medium, there are many other alternatives, eg, Ficoll, Percoll, Nycodenz, or Metrizamide.8,15 Discontinuous gradients as well as step gradients have been applied successfully for the separation of early from late endosomes.11 Similar gradients were also applied for the purification of intact Golgi stacks10,16 as well as Golgi-derived transport vesicles.17
For better resolution, equilibrium separations with continuous gradients are the method of choice. After centrifugation to equilibrium, membranes distribute throughout the entire gradient according to their specific densities.14,18 A drawback of continuous gradients can be the low enrichment of organelles, resulting in rather diluted fractions.
| Quality Control |
|---|
|
|
|---|
|
| Protein Fractionation |
|---|
|
|
|---|
| Organelle Proteome Analysis |
|---|
|
|
|---|
| Some Successful Examples |
|---|
|
|
|---|
A comprehensive proteomics analysis of human nucleoli was recently performed.29 The authors of this study identified 271 proteins in the nucleoli and showed that nucleoli have a surprisingly large protein complexity. The fact that many novel factors and separate classes of proteins were identified supports the view that the nucleolus might perform additional functions beyond its known role in ribosome subunit biogenesis. This extensive proteomics analysis also demonstrated for the first time that the protein composition of nucleoli is not static and can alter significantly in response to the metabolic state of the cell.
Starting from a classical subcellular fractionation approach combined with high-resolution 2D gel electrophoresis and mass spectrometry analysis, the proteome of endosomes was investigated.14 In continuation of this work, the authors have identified a novel adapter molecule, named p14, for a mitogen-activated protein kinase scaffolding complex on the cytoplasmic face of late endosomes.19 Finally, reconstitution of this multiprotein signaling complex and depletion of endogenous levels of the involved proteins by RNAi (RNA interference) revealed that the late endosomal localization of the p14mitogen-activated protein kinase scaffold complex is essential for signal transduction.30,31
| Subcellular Fractionation and Protein Identification in Cardiac Research |
|---|
|
|
|---|
B-crystallin, and myotonic dystrophy kinase binding protein (MKBP) were predominantly in cytosolic fractions. Chromatography with molecular sieving columns revealed that HSP20 and
B-crystallin were associated in an aggregate of
200 kDa, and the phosphorylation of HSP20 was determined by 2D gel electrophoresis and immunoblotting.33 Signal transduction protein complexes and their activation, eg, protein kinase C activation, were analyzed as described above by subcellular fractionation, detergent extraction, and Western blotting in cultures of neonatal rat ventricular myocytes after electric stimulation.34
Caveolae are plasma membrane invaginations that are enriched in cholesterol, sphingolipids, and the marker protein caveolin. Muscle cell caveolae may function as specialized membrane microdomains in which the dystrophin-glycoprotein complex and cellular signaling molecules reside. These fractions were prepared directly from hearts from wild-type and caeolin-3 knockout animals35 with very similar protocols as used, for example, for cultured epithelial cells.36 Proteomic analysis of rabbit ventricular myocytes after detergent extraction revealed a novel posttranslational modification to myosin light chain 1.37 Specialized detergent extraction protocols in combination with subcellular fractionation allowed solubilization and mapping of cardiac sarcoplasmic reticulum proteins.38 Recently, mitochondria were purified from bovine heart by a combination of detergent extraction and sucrose gradient centrifugation as described above and finally separated on high-resolution 2D gels.39 In another study, sucrose gradient centrifugation was used to partially resolve mitochondrial protein complexes whose individual protein components were separated by one-dimensional PAGE. Total in-gel processing and subsequent detection by mass spectrometry and rigorous bioinformatic analysis yielded a total of 615 distinct protein identifications.40
| Concluding Remarks |
|---|
|
|
|---|
| Acknowledgments |
|---|
Received February 10, 2003; revision received April 3, 2003; accepted April 3, 2003.
| References |
|---|
|
|
|---|
2. Klose J. Protein mapping by combined isoelectric focusing and electrophoresis of mouse tissues: a novel approach to testing for induced point mutations in mammals. Humangenetik. 1975; 26: 231243.[Medline] [Order article via Infotrieve]
3. OFarrell PH. High resolution two-dimensional electrophoresis of proteins. J Biol Chem. 1975; 250: 40074021.
4. Huber LA. Opinion: is proteomics heading in the wrong direction? Nat Rev Mol Cell Biol. 2003; 4: 7480.[CrossRef][Medline] [Order article via Infotrieve]
5. Pasquali C, Fialka I, Huber LA. Subcellular fractionation, electromigration analysis and mapping of organelles. J Chromatogr B Biomed Sci Appl. 1999; 722: 89102.[CrossRef][Medline] [Order article via Infotrieve]
6. Gavin AC, Bosche M, Krause R, Grandi P, Marzioch M, Bauer A, Schultz J, Rick JM, Michon AM, Cruciat CM, Remor M, Hofert C, Schelder M, Brajenovic M, Ruffner H, Merino A, Klein K, Hudak M, Dickson D, Rudi T, Gnau V, Bauch A, Bastuck S, Huhse B, Leutwein C, Heurtier MA, Copley RR, Edelmann A, Querfurth E, Rybin V, Drewes G, Raida M, Bouwmeester T, Bork P, Seraphin B, Kuster B, Neubauer G, Superti-Furga G. Functional organization of the yeast proteome by systematic analysis of protein complexes. Nature. 2002; 415: 141147.[CrossRef][Medline] [Order article via Infotrieve]
7. Gorg A, Obermaier C, Boguth G, Harder A, Scheibe B, Wildgruber R, Weiss W. The current state of two-dimensional electrophoresis with immobilized pH gradients. Electrophoresis. 2000; 21: 10371053.[CrossRef][Medline] [Order article via Infotrieve]
8. Fleischer S, Kervina M. Subcellular fractionation of rat liver. Methods Enzymol. 1974; 31: 641.[Medline] [Order article via Infotrieve]
9. Palade GE. Cell fractionation: importance to cell-free systems development. Prog Clin Biol Res. 1988; 270: xixxx.[Medline] [Order article via Infotrieve]
10. Howell KE, Devaney E, Gruenberg J. Subcellular fractionation of tissue culture cells. Trends Biochem Sci. 1989; 14: 4447.[CrossRef][Medline] [Order article via Infotrieve]
11. Gruenberg J, Howell KE. Fusion in the endocytic pathway reconstituted in a cell-free system using immuno-isolated fractions. Prog Clin Biol Res. 1988; 270: 317331.[Medline] [Order article via Infotrieve]
12. Pasquali C, Fialka I, Huber LA. Preparative two-dimensional gel electrophoresis of membrane proteins. Electrophoresis. 1997; 18: 25732581.[CrossRef][Medline] [Order article via Infotrieve]
13. Li EL, Perdue JF. An airfuge centrifugation procedure for the measurement of ligand binding to membrane-associated and detergent-solubilized plasma membrane receptors. J Biochem Biophys Methods. 1980; 3: 207217.[CrossRef][Medline] [Order article via Infotrieve]
14. Fialka I, Pasquali C, Lottspeich F, Ahorn H, Huber LA. Subcellular fractionation of polarized epithelial cells and identification of organelle-specific proteins by two-dimensional gel electrophoresis. Electrophoresis. 1997; 18: 25822590.[CrossRef][Medline] [Order article via Infotrieve]
15. Fleischer B, Zambrano F, Fleischer S. Biochemical characterization of the Golgi complex of mammalian cells. J Supramol Struct. 1974; 2: 737750.[CrossRef][Medline] [Order article via Infotrieve]
16. Taylor RS, Fialka I, Jones SM, Huber LA, Howell KE. Two-dimensional mapping of the endogenous proteins of the rat hepatocyte Golgi complex cleared of proteins in transit. Electrophoresis. 1997; 18: 26012612.[CrossRef][Medline] [Order article via Infotrieve]
17. Wandinger-Ness A, Bennett MK, Antony C, Simons K. Distinct transport vesicles mediate the delivery of plasma membrane proteins to the apical and basolateral domains of MDCK cells. J Cell Biol. 1990; 111: 9871000.
18. Fialka I, Steinlein P, Ahorn H, Bock G, Burbelo PD, Haberfellner M, Lottspeich F, Paiha K, Pasquali C, Huber LA. Identification of syntenin as a protein of the apical early endocytic compartment in Madin-Darby canine kidney cells. J Biol Chem. 1999; 274: 2623326239.
19. Wunderlich W, Fialka I, Teis D, Alpi A, Pfeifer A, Parton RG, Lottspeich F, Huber LA. A novel 14-kilodalton protein interacts with the mitogen-activated protein kinase scaffold mp1 on a late endosomal/lysosomal compartment. J Cell Biol. 2001; 152: 765776.
20. Huber LA, Fialka I, Paiha K, Hunziker W, Sacks DB, Bahler M, Way M, Gagescu R, Gruenberg J. Both calmodulin and the unconventional myosin Myr4 regulate membrane trafficking along the recycling pathway of MDCK cells. Traffic. 2000; 1: 494503.[CrossRef][Medline] [Order article via Infotrieve]
21. Gagescu R, Demaurex N, Parton RG, Hunziker W, Huber LA, Gruenberg J. The recycling endosome of Madin-Darby canine kidney cells is a mildly acidic compartment rich in raft components. Mol Biol Cell. 2000; 11: 27752791.
22. Howell KE, Gruenberg J, Ito A, Palade GE. Immuno-isolation of subcellular components. Prog Clin Biol Res. 1988; 270: 7790.[Medline] [Order article via Infotrieve]
23. Fujiki Y, Hubbard AL, Fowler S, Lazarow PB. Isolation of intracellular membranes by means of sodium carbonate treatment: application to endoplasmic reticulum. J Cell Biol. 1982; 93: 97102.
24. Burkhardt J, Huber LA, Dieplinger H, Blocker A, Griffiths G, Desjardins M. Gaining insight into a complex organelle, the phagosome, using two-dimensional gel electrophoresis. Electrophoresis. 1995; 16: 22492257.[CrossRef][Medline] [Order article via Infotrieve]
25. Fialka I, Pasquali C, Kurzbauer R, Lottspeich F, Huber LA. Loss of epithelial polarity is accompanied by differential association of proteins with intracellular membranes. Electrophoresis. 1999; 20: 331343.[CrossRef][Medline] [Order article via Infotrieve]
26. Gygi SP, Rist B, Gerber SA, Turecek F, Gelb MH, Aebersold R. Quantitative analysis of complex protein mixtures using isotope-coded affinity tags. Nat Biotechnol. 1999; 17: 994999.[CrossRef][Medline] [Order article via Infotrieve]
27. Garin J, Diez R, Kieffer S, Dermine JF, Duclos S, Gagnon E, Sadoul R, Rondeau C, Desjardins M. The phagosome proteome: insight into phagosome functions. J Cell Biol. 2001; 152: 165180.
28. Gagnon E, Duclos S, Rondeau C, Chevet E, Cameron PH, Steele-Mortimer O, Paiement J, Bergeron JJ, Desjardins M. Endoplasmic reticulum-mediated phagocytosis is a mechanism of entry into macrophages. Cell. 2002; 110: 119131.[CrossRef][Medline] [Order article via Infotrieve]
29. Andersen JS, Lyon CE, Fox AH, Leung AK, Lam YW, Steen H, Mann M, Lamond AI. Directed proteomic analysis of the human nucleolus. Curr Biol. 2002; 12: 111.[CrossRef][Medline] [Order article via Infotrieve]
30. Teis D, Wunderlich W, Huber LA. Localization of the MP1-MAPK scaffold complex to endosomes is mediated by p14 and required for signal transduction. Dev Cell. 2002; 3: 803814.[CrossRef][Medline] [Order article via Infotrieve]
31. Felberbaum-Corti M, Gruenberg J. Signaling from the far side. Mol Cell. 2002; 10: 12591260.[CrossRef][Medline] [Order article via Infotrieve]
32. Bunger R, Soboll S. Cytosolic adenylates and adenosine release in perfused working heart: comparison of whole tissue with cytosolic non-aqueous fractionation analyses. Eur J Biochem. 1986; 159: 203213.[Medline] [Order article via Infotrieve]
33. Pipkin W, Johnson JA, Creazzo TL, Burch J, Komalavilas P, Brophy C. Localization, macromolecular associations, and function of the small heat shock-related protein HSP20 in rat heart. Circulation. 2003; 107: 469476.
34. Strait JB, Samarel AM. Isoenzyme-specific protein kinase C and c-Jun N-terminal kinase activation by electrically stimulated contraction of neonatal rat ventricular myocytes. J Mol Cell Cardiol. 2000; 32: 15531566.[CrossRef][Medline] [Order article via Infotrieve]
35. Woodman SE, Park DS, Cohen AW, Cheung MW, Chandra M, Shirani J, Tang B, Jelicks LA, Kitsis RN, Christ GJ, Factor SM, Tanowitz HB, Lisanti MP. Caveolin-3 knock-out mice develop a progressive cardiomyopathy and show hyperactivation of the p42/44 MAPK cascade. J Biol Chem. 2002; 277: 3898838997.
36. Oliferenko S, Paiha K, Harder T, Gerke V, Schwarzler C, Schwarz H, Beug H, Gunthert U, Huber LA. Analysis of CD44-containing lipid rafts: recruitment of annexin II and stabilization by the actin cytoskeleton. J Cell Biol. 1999; 146: 843854.
37. Arrell DK, Neverova I, Fraser H, Marban E, Van Eyk JE. Proteomic analysis of pharmacologically preconditioned cardiomyocytes reveals novel phosphorylation of myosin light chain 1. Circ Res. 2001; 89: 480487.
38. Macri J, McGee B, Thomas JN, Du P, Stevenson TI, Kilby GW, Rapundalo ST. Cardiac sarcoplasmic reticulum and sarcolemmal proteins separated by two-dimensional electrophoresis: surfactant effects on membrane solubilization. Electrophoresis. 2000; 21: 16851693.[CrossRef][Medline] [Order article via Infotrieve]
39. Hanson BJ, Schulenberg B, Patton WF, Capaldi RA. A novel subfractionation approach for mitochondrial proteins: a three-dimensional mitochondrial proteome map. Electrophoresis. 2001; 22: 950959.[CrossRef][Medline] [Order article via Infotrieve]
40. Taylor SW, Fahy E, Zhang B, Glenn GM, Warnock DE, Wiley S, Murphy AN, Gaucher SP, Capaldi RA, Gibson BW, Ghosh SS. Characterization of the human heart mitochondrial proteome. Nat Biotechnol. 2003; 21: 281286.[CrossRef][Medline] [Order article via Infotrieve]
This article has been cited by other articles:
![]() |
A. Hryniewicz-Jankowska, P. K. Choudhary, L. P. Ammann, C. T. Quinn, and S. R. Goodman Monocyte Protein Signatures of Disease Severity in Sickle Cell Anemia Experimental Biology and Medicine, February 1, 2009; 234(2): 210 - 221. [Abstract] [Full Text] [PDF] |
||||
![]() |
A. J. Groen, S. C. de Vries, and K. S. Lilley A Proteomics Approach to Membrane Trafficking Plant Physiology, August 1, 2008; 147(4): 1584 - 1589. [Full Text] [PDF] |
||||
![]() |
A. Hryniewicz-Jankowska, P. K. Choudhary, and S. R. Goodman Variation in the Monocyte Proteome Experimental Biology and Medicine, July 1, 2007; 232(7): 967 - 976. [Abstract] [Full Text] [PDF] |
||||
![]() |
T. Stasyk, N. Schiefermeier, S. Skvortsov, H. Zwierzina, J. Peranen, G. K. Bonn, and L. A. Huber Identification of Endosomal Epidermal Growth Factor Receptor Signaling Targets by Functional Organelle Proteomics Mol. Cell. Proteomics, May 1, 2007; 6(5): 908 - 922. [Abstract] [Full Text] [PDF] |
||||
![]() |
M.-J. Han and S. Y. Lee The Escherichia coli Proteome: Past, Present, and Future Prospects Microbiol. Mol. Biol. Rev., June 1, 2006; 70(2): 362 - 439. [Abstract] [Full Text] [PDF] |
||||
![]() |
T. Sparre, M. R. Larsen, P. E. Heding, A. E. Karlsen, O. N. Jensen, and F. Pociot Unraveling the Pathogenesis of Type 1 Diabetes with Proteomics: Present And Future Directions Mol. Cell. Proteomics, April 1, 2005; 4(4): 441 - 457. [Abstract] [Full Text] [PDF] |
||||
![]() |
C. C. Wu, M. J. MacCoss, G. Mardones, C. Finnigan, S. Mogelsvang, J. R. Yates III, and K. E. Howell Organellar Proteomics Reveals Golgi Arginine Dimethylation Mol. Biol. Cell, June 1, 2004; 15(6): 2907 - 2919. [Abstract] [Full Text] [PDF] |
||||
![]() |
M. Mayr, R. Siow, Y.-L. Chung, U. Mayr, J. R. Griffiths, and Q. Xu Proteomic and Metabolomic Analysis of Vascular Smooth Muscle Cells: Role of PKC{delta} Circ. Res., May 28, 2004; 94(10): e87 - e96. [Abstract] [Full Text] [PDF] |
||||
![]() |
I. M. Cristea, S. J. Gaskell, and A. D. Whetton Proteomics techniques and their application to hematology Blood, May 15, 2004; 103(10): 3624 - 3634. [Abstract] [Full Text] [PDF] |
||||
![]() |
J. W. Zolg and H. Langen How Industry Is Approaching the Search for New Diagnostic Markers and Biomarkers Mol. Cell. Proteomics, April 1, 2004; 3(4): 345 - 354. [Abstract] [Full Text] [PDF] |
||||
![]() |
P. Ping Identification of Novel Signaling Complexes by Functional Proteomics Circ. Res., October 3, 2003; 93(7): 595 - 603. [Abstract] [Full Text] [PDF] |
||||
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
|
Circulation Research Home | Subscriptions | Archives | Feedback | Authors | Help | AHA Journals Home | Search Copyright © 2003 American Heart Association, Inc. All rights reserved. Unauthorized use prohibited. |