doi:10.1369/jhc.7A7195.2007
Volume 55 (8): 805-812, 2007 Copyright ©The Histochemical Society, Inc. Effects of Detergents on the Redistribution of Gangliosides and GPI-anchored Proteins in Brain Tissue Sections
Department of Medical Biology (MH-L,KV) and Department of Chemistry and Biochemistry (BV,GL), University of Osijek School of Medicine, Osijek, Croatia; Departments of Pharmacology and Neurosciences, The Johns Hopkins University School of Medicine, Baltimore, Maryland (RLS); and Department of Biochemistry and Molecular Biology, Faculty of Pharmacy and Biochemistry, University of Zagreb, Zagreb, Croatia (GL) Correspondence to: Dr Gordan Lauc, Department of Chemistry and Biochemistry, University of Osijek School of Medicine, J. Huttlera 4, 31000, Osijek, Croatia. E-mail: glauc{at}pharma.hr
Gangliosides and glycosylphosphatidylinositol (GPI)-anchored proteins contain lipid tails that tether them to the outer side of the cell membrane. This mode of association with the cell membrane enables them to take part in the organization of lipid rafts, but it also permits gangliosides and GPI-anchored proteins to be actively released from one cell and inserted into the membrane of another cell. Recently, we reported that under conditions of lipid raft isolation, Triton X-100 causes significant redistribution of both gangliosides and GPI-anchored proteins. Aiming to find a less disruptive detergent, we evaluated the effects of CHAPS, Saponin, deoxycholic acid, Trappsol, Tween 20, Triton X-100, Brij 96V, Brij 98, and SDS on brain tissue sections. At room temperature, all detergents (1% concentration) extracted significant amounts of both gangliosides and Thy-1. At 4C, the extraction was weaker, but Triton X-100, CHAPS, and deoxycholic acid caused significant redistribution of GD1a and Thy-1 from gray matter into the white matter. Both redistribution and extraction were significantly augmented when sections were incubated with detergents in the presence of primary antibodies. Of the nine tested detergents, none is the ideal choice. However, Brij 96V appears to be able to sufficiently reveal myelin epitopes while causing the least amount of artifacts. This manuscript contains online supplemental material at http://www.jhc.org. Please visit this article online to view these materials. (J Histochem Cytochem 55:805812, 2007)
Key Words: gangliosides glycosylphosphatidylinositol-anchored proteins immunochemical analysis brain detergents lipid rafts
GANGLIOSIDES AND GLYCOSYLPHOSPHATIDYLINOSITOL (GPI)-anchored proteins arise from different biochemical pathways, but have the same general assembly plan: they both have lipid anchors that tether them to the cell membrane and relatively large hydrophilic domains that protrude into the extracellular space. This type of attachment to the cell membrane enables gangliosides and GPI-anchored proteins to take part in the organization of lipid rafts, but it also allows them to be released from the membrane of one cell and inserted into the membrane of another cell in a regulated manner (Lauc and Heffer-Lauc 2006
Patterns of ganglioside expression change with cell growth and differentiation, viral transformation, ontogenesis, and oncogenesis (Hakomori 1981
Triton X-100 is among the most commonly used detergents for the analysis of membrane antigens, but we recently reported that its presence during an immunostaining procedure caused significant redistribution of gangliosides and GPI-anchored proteins (Heffer-Lauc et al. 2005
Materials Mice lacking complex brain gangliosides (including GM1 and GD1a) were generated by disrupting B4 galnt1 (previously known as Galgt1), the gene that encodes UDP-GalNAc:GM3/GD3 N-acetylgalactosaminyltransferase (B4 galnt1-null mice) (Liu et al. 1999
Immunohistochemical Analysis
Primary antibodies were incubated overnight in blocking solution. Anti-GM1 and anti-GD1a were produced as described previously (Schnaar et al. 2002 Lipid extraction for the visualization of MAG was performed by dehydration in gradient of ethanol, chloroform/methanol extraction, and subsequent rehydration in gradient of ethanol prior to immunohistochemistry. All tissue sections for one experiment were incubated for exactly the same time in all steps, and all images were collected using the same settings; thus, the differences in the intensity of staining reflect differences in the amount of bound antibody.
In an effort to enable concurrent immunohistochemical analysis of myelin membrane receptors (like MAG) and gangliosides, we analyzed the effects of different detergents: CHAPS, saponin, deoxycholic acid, Trappsol, Tween 20, Triton X-100, Brij 96V, Brij 98, SDS, and glycerol. Published protocols reported use of these detergents in concentrations from 0.1% to 10% (Bo et al. 1995 Effects on the distribution of GD1a ganglioside of 2-hr pretreatment of brain sections with detergents at room temperature are shown in Figure 1 . When immunostaining was performed without any detergents, GD1a was located primarily on neuronal bodies, with practically no staining of the white matter. All detergents, to some extent, significantly extracted GD1a from the gray matter. CHAPS, deoxycholic acid, Triton X-100, Brij 96V, and SDS were particularly detrimental and removed nearly all GD1a from the tissue.
Fluidity of membranes is much lower at lower temperatures, and as shown in Figure 2 , we found that detergents were much less efficient in extracting GD1a when used at 4C. Previously, we reported that at this temperature, Triton X-100 causes redistribution of GD1a from gray matter into the white matter of cerebellum (Heffer-Lauc et al. 2005
Thy-1 is a GPI-anchored protein with a relatively large hydrophilic area that is tethered to the membrane by a relatively small lipid portion of the molecule. We have previously shown that Triton X-100 causes a redistribution of Thy-1 very similar to that of GD1a. We repeated the same experiments as shown in Figures 1 and 2 for GD1a with antibodies against Thy-1 and obtained similar results as for GD1a (presented in supplementary Figures 1 and 2). Unlike GD1a and Thy-1, which are located mainly in the gray matter, GM1 is found predominately in the hydrophobic myelin sheets of the cerebellar white matter. In our previous study, we did not observe any redistribution of GM1 with Triton X-100. As shown in Figure 3 , at 4C, none of the studied detergents caused redistribution of GM1 from white matter into the gray matter. However, some of the detergents (particularly SDS and deoxycholic acid) extracted significant amounts of GM1 from tissue sections, resulting in markedly reduced GM1 staining. This effect was even more prominent when the incubation with detergents was performed at room temperature (see supplementary Figure 3).
In the experiments presented above, tissue sections were treated with detergents for 2 hr before the blocking step and all other steps were performed at 4C (from blocking up to development with the substrate). However, in some published protocols, detergents are present in blocking and also during the incubation with primary antibodies. This not only prolongs the incubation in the presence of detergents, but also adds the effect of antibodies, which act as a large bulky handle that can pull lipid-anchored antigens out of the membrane. Aiming to evaluate the effects of this prolonged incubation with detergents in the presence of primary antibodies, we designed and performed the following experiment (presented in Figure 4 ).
Tissue sections of cerebellum and medulla from wild-type mice were coincubated for 16 hr with sections of spinal cord from B4 galnt1-null mice (lacking complex gangliosides, including GD1a) in 300 µl blocking solution containing antibodies against GD1a. When there was no detergent in the blocking solution, GD1a was found to be located primarily in the gray matter of cerebellum. There was no GD1a staining in B4 galnt1-null mice. However, when CHAPS, deoxycholic acid, or Triton X-100 was included in the blocking solution and solution of primary antibody, GD1a redistributed into the white matter of wild-type mouse cerebellum and also into the white matter of B4 galnt1-null mice spinal cord. Although it could be speculated that these detergents only revealed previously cryptic GD1a in the white matter of wild-type mouse cerebellum, the appearance of GD1a in B4 galnt1-null mice could only be explained by its redistribution from wild-type mouse cerebellum into B4 galnt1-null mice spinal cord during their coincubation in the presence of detergents. Interestingly, other detergents studied did not cause this type of redistribution.
Immunohistochemical analysis is a common basic method that is a prerequisite for subsequent functional studies and in vivo imaging. However, antibodies are bulky molecules that need a significant amount of space to be able to bind to corresponding epitopes. Many molecules are either packed too close together or masked by other molecules, and the analysis of these structures is possible only when detergents are used to enable access of antibodies to the studied epitopes. Triton X-100 is one of the detergents most commonly used for the immunohistochemical analysis of membrane antigens and the isolation of membrane rafts (Edidin 2003
At room temperature, nearly all detergents studied extracted a significant amount of lipid-anchored antigens from the tissues (Figure 1 and supplementary Figures 1 and 3). Depending on the type of detergent and the volume of buffer, extracted gangliosides and GPI-anchored proteins either remained in the solution or entered other tissues, primarily highly hydrophobic sheets of myelin. The only exception was GM1, which is physiologically located predominantly in myelin; detergents only extracted GM1 from the tissue, and it never entered any other tissue (Figure 3 and supplementary Figure 3). This observation is consistent with our previously reported results (Heffer-Lauc et al. 2005 In conclusion, the use of detergents has significant adverse affects on the immunochemical analysis of gangliosides and GPI-anchored proteins. Different detergents and detergent concentrations, and varying time and temperature, were found to affect lipid-anchored molecules, leading to immunohistochemical localization artifacts. Triton X-100 is used in most protocols for brain tissue staining and isolation of lipid rafts, but its use is associated with significant redistribution of lipid-anchored molecules, both within and between tissue sections. Although this might not be a problem in some studies, when gangliosides and GPI-anchored protein molecules are being examined, Triton X-100 should be avoided because it might significantly compromise obtained results. The same is true for CHAPS and deoxycholic acid. Use at room temperature of any of the detergents studied will cause significant extraction of lipid-anchored molecules, especially GPI-anchored proteins. For concurrent immunohistochemical localization of lipid-anchored molecules and myelin proteins, the length of exposure to detergents should be reduced to a minimum, and all steps of the immunostaining procedure should be performed at 4C, because this significantly reduces detergent-induced artifacts. None of the nine detergents studied seems to be the perfect solution. Saponin, Trappsol, Tween 20, and Brij 98 caused less redistribution than other detergents, but their downside was that they were also not efficient in revealing cryptic epitopes like MAG. Brij 96V appears to be the least distorting choice of detergent; when used at 4C, it caused the least amount of redistribution but still sufficiently revealed myelin epitopes (Table 1 ). However, the behavior of lipid-linked epitopes varies, and other detergents might be optimal for other systems. In any case, it is very important to keep in mind that numerous control experiments are needed to avoid artifacts when lipid-linked molecules are studied in the presence of detergents.
This work was supported by grants 219-0061194-2158 and 219-0061194-2023 from the Croatian Ministry of Science, Education, and Sport and by Grant 2R37NS037096-24 from the National Institutes of Health.
Received for publication January 21, 2007; accepted March 19, 2007
Bo L, Quarles RH, Fujita N, Bartoszewicz Z, Sato S, Trapp BD (1995) Endocytic depletion of L-MAG from CNS myelin in quaking mice. J Cell Biol 131:18111820 Edidin M (2003) The state of lipid rafts: from model membranes to cells. Annu Rev Biophys Biomol Struct 32:257283[CrossRef][Medline] Hakomori S (1981) Glycosphingolipids in cellular interaction, differentiation, and oncogenesis. Annu Rev Biochem 50:733764[CrossRef][Medline] Heffer-Lauc M, Cacic M, Judas M, Muthing J (1996) Anti-GM3 (II3Neu5Ac-lactosylceramide) ganglioside antibody labels human fetal Purkinje neurons during the critical stage of cerebellar development. Neurosci Lett 213:9194[CrossRef][Medline] Heffer-Lauc M, Cacic M, Serman D (1998) C-series polysialogangliosides are expressed on stellate neurons of adult human cerebellum. Glycoconj J 15:423426[CrossRef][Medline] Heffer-Lauc M, Lauc G, Nimrichter L, Fromholt SE, Schnaar RL (2005) Membrane redistribution of gangliosides and glycosylphosphatidylinositol-anchored proteins in brain tissue sections under conditions of lipid raft isolation. Biochim Biophys Acta 1686:200208 Kawashima I, Nakamura O, Tai T (1992) Antibody responses to ganglio-series gangliosides in different strains of inbred mice. Mol Immunol 29:625632[CrossRef][Medline] Kloppel TM, Keenan TW, Freeman MJ, Morre DJ (1977) Glycolipid-bound sialic acid in serum: increased levels in mice and humans bearing mammary carcinomas. Proc Natl Acad Sci USA 74:30113013 Kotani M, Kawashima I, Ozawa H, Terashima T, Tai T (1993) Differential distribution of major gangliosides in rat central nervous system detected by specific monoclonal antibodies. Glycobiology 3:137146 Kotani M, Terashima T, Tai T (1995) Developmental changes of ganglioside expressions in postnatal rat cerebellar cortex. Brain Res 700:4058[CrossRef][Medline] Ladisch S, Gillard B, Wong C, Ulsh L (1983) Shedding and immunoregulatory activity of YAC-1 lymphoma cell gangliosides. Cancer Res 43:38083813 Lauc G, Heffer-Lauc M (2006) Shedding and uptake of gangliosides and glycosylphosphatidylinositol-anchored proteins. Biochim Biophys Acta 1760:584602[Medline] Letinic K, Heffer-Lauc M, Rosner H, Kostovic I (1998) C-pathway polysialogangliosides are transiently expressed in the human cerebrum during fetal development. Neuroscience 86:15[CrossRef][Medline] Liu Y, Wada R, Kawai H, Sango K, Deng C, Tai T, McDonald MP, et al. (1999) A genetic model of substrate deprivation therapy for a glycosphingolipid storage disorder. J Clin Invest 103:497505[Medline] Lunn MP, Johnson LA, Fromholt SE, Itonori S, Huang J, Vyas AA, Hildreth JE, et al. (2000) High-affinity anti-ganglioside IgG antibodies raised in complex ganglioside knockout mice: reexamination of GD1a immunolocalization. J Neurochem 75:404412[CrossRef][Medline] Masserini M, Freire E (1987) Kinetics of ganglioside transfer between liposomal and synaptosomal membranes. Biochemistry 26:237242[CrossRef][Medline] Palestini P, Pitto M, Sonnino S, Omodeo-Sale MF, Masserini M (1995) Spontaneous transfer of GM3 ganglioside between vesicles. Chem Phys Lipids 77:253260[CrossRef][Medline] Portoukalian J (2000) Immunogenicity of glycolipids. Clin Rev Allergy Immunol 19:7378[CrossRef][Medline] Portoukalian J, Zwingelstein G, Abdul-Malak N, Dore JF (1978) Alteration of gangliosides in plasma and red cells of humans bearing melanoma tumors. Biochem Biophys Res Commun 85:916920[Medline] Rösner H (1993) Developmental expression of gangliosides in vivo and in vitro. In Roth J, Rutishauser U, Troy FA, eds. Polysialic Acid. Basel, Birkhäuser Verlag, 279297 Rösner H (2003) Developmental expression and possible roles of gangliosides in brain development. Prog Mol Subcell Biol 32:4973[Medline] Schnaar RL, Fromholt SE, Gong Y, Vyas AA, Laroy W, Wayman DM, Heffer-Lauc M, et al. (2002) Immunoglobulin G-class mouse monoclonal antibodies to major brain gangliosides. Anal Biochem 302:276284[CrossRef][Medline] Schwarz A, Futerman AH (1996) The localization of gangliosides in neurons of the central nervous system: the use of anti-ganglioside antibodies. Biochim Biophys Acta 1286:247267[Medline] Sheikh KA, Sun J, Liu Y, Kawai H, Crawford TO, Proia RL, Griffin JW, et al. (1999) Mice lacking complex gangliosides develop Wallerian degeneration and myelination defects. Proc Natl Acad Sci USA 96:75327537 Wang X, Chun SJ, Treloar H, Vartanian T, Greer CA, Strittmatter SM (2002) Localization of Nogo-A and Nogo-66 receptor proteins at sites of axon-myelin and synaptic contact. J Neurosci 22:55055515
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