Endocytosis

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Forms of endocytosis

The endocytosis is a cellular process in which by invagination of areas of the cell membrane from the vicinity of the cell fluid and particles are taken. It also regulates the composition of the cell membrane and mediates the transport of receptors from the cell membrane. It occurs in all eukaryotes .

properties

Endocytosis occurs in eukaryotes via four mechanisms, via clathrin , via caveolae , via phagocytosis or via macropinocytosis . A vesicle on the inside of the cell membrane is pinched off into the cell interior. The vesicles then fuse with endosomes and lysosomes in the endomembrane system . In yeast , endocytosis begins in certain areas of the cell membrane (on one of the 50 to 100 Eisosomes on the cell surface), which contain the proteins Pil1 , Lsp1 , Sur7 , Eis1 , Seg1 and Ygr130C . The opposite process of fusing vesicles with the cell membrane is known as exocytosis . Endocytosis and exocytosis are regulatory mechanisms for the homeostasis of the cell membrane, ie both processes control the composition and expansion of the cell membrane.

Clathrin

Receptor-mediated endocytosis via clathrin

Clathrin is located in the clathrin-coated pits ( clathrin-coated wells ) of the cell membrane. This mechanism is the main mechanism of endocytosis in most cells. Over 50 proteins are involved in this.

Caveolae

Caveolae are membrane areas of around 50 nm that are not found on all cells in an organism. They come more often on cell membranes of the smooth muscles , type I pneumocytes , fibroblasts , adipocytes and endothelial cells and can take up up to a third of the cell membrane. They are a form of lipid rafts . They often contain caveolins , cavins , cholesterol and sphingolipids . Presumably the caveolae have an additional role as sensors for mechanical stress.

Phagocytosis

During phagocytosis, vesicles with a diameter of 750 nm are pinched off which contain particles from the environment, e.g. B. Dust particles, cell debris from apoptosis and necrosis and pathogens . Transport takes place along the actin cytoskeleton. Phagocytosis can be divided into four phases: a resting phase, the formation of a depression in the cell membrane, the formation of pseudopodia and active transport along the actin cytoskeleton including reorganization, and the restoration of the actin cytoskeleton. Phagocytosis is initiated by activating PAMP receptors . As secondary messenger substances, phosphoinositides are involved in the transmission of signals during phagocytosis. The signaling flows into the calcineurin - NFAT signaling pathway. Phagocytosis is an important mechanism of the immune response , e.g. B. macrophages and other professional antigen presenting cells invade pathogens and then amplify an immune response. Every day around 200 to 300 billion cells die in the adult human body, the fragments of which are phagocytosed and broken down.

Macropinocytosis

In macropinocytosis, pleated areas of the membrane are inversed, resulting in significantly larger vesicle diameters ( macropinosomes ), which absorb larger volumes of the surrounding fluid in an unspecific manner .

literature

Individual evidence

  1. Pierre J. Courtoy: Endocytosis. Springer Science & Business Media, 2013, ISBN 978-3-642-84295-5 . Preface.
  2. ^ Marsh, Mark: Endocytosis . Oxford University Press, 2001, ISBN 978-0-19-963851-2 .
  3. C. Deng, X. Xiong, AN Krutchinsky: Unifying fluorescence microscopy and mass spectrometry for studying protein complexes in cells. In: Molecular & cellular proteomics: MCP. Volume 8, number 6, June 2009, pp. 1413-1423, doi : 10.1074 / mcp.M800397-MCP200 , PMID 19269952 , PMC 2690482 (free full text).
  4. A. Gauthier-Kemper, M. Kahms, J. Klingauf: Restoring synaptic vesicles during compensatory endocytosis. In: Essays in biochemistry. Volume 57, 2015, pp. 121-134, doi : 10.1042 / bse0570121 , PMID 25658349 .
  5. V. Bitsikas, IR Corrêa, BJ Nichols: clathrin-independent pathways do not contribute to Significantly endocytic flux. In: eLife. Volume 3, 2014, p. E03970, doi : 10.7554 / eLife.03970 , PMID 25232658 , PMC 4185422 (free full text).
  6. T. Kirchhausen, D. Owen, SC Harrison: Molecular Structure, Function, and Dynamics of Clathrin-Mediated Membrane Traffic. In: Cold Spring Harbor Perspectives in Biology. 6, 2014, p. A016725, doi : 10.1101 / cshperspect.a016725 .
  7. BL Goode, JA Eskin, B. Wendland: Actin and endocytosis in budding yeast. In: Genetics. Volume 199, number 2, February 2015, pp. 315-358, doi : 10.1534 / genetics.112.145540 , PMID 25657349 , PMC 4317646 (free full text).
  8. CJ Merrifield, M. Kaksonen: Endocytic accessory factors and regulation of clathrin-mediated endocytosis. In: Cold Spring Harbor perspectives in biology. Volume 6, Number 11, November 2014, p. A016733, doi : 10.1101 / cshperspect.a016733 , PMID 25280766 .
  9. UE Martinez-Outschoorn, F. Sotgia, MP Lisanti: caveolae and signaling in cancer. In: Nature Reviews Cancer . Volume 15, Number 4, April 2015, pp. 225-237, doi : 10.1038 / nrc3915 , PMID 25801618 .
  10. ^ RG Parton, K. Simons: The multiple faces of caveolae. In: Nature reviews. Molecular cell biology. Volume 8, Number 3, March 2007, pp. 185-194, doi : 10.1038 / nrm2122 , PMID 17318224 (review).
  11. VL Reeves, CM Thomas, EJ Smart: Lipid rafts, caveolae and GPI-linked proteins. In: Advances in Experimental Medicine and Biology . Volume 729, 2012, pp. 3-13, doi : 10.1007 / 978-1-4614-1222-9_1 , PMID 22411310 .
  12. O. Kovtun, VA tillu, N. Ariotti, RG Parton, BM Collins: Cavin family proteins and the assembly of caveolae. In: Journal of cell science. Volume 128, number 7, April 2015, pp. 1269-1278, doi : 10.1242 / jcs.167866 , PMID 25829513 , PMC 4379724 (free full text).
  13. P. NASSOY, C. Lamaze: Stressing caveolae new role in cell mechanics. In: Trends in cell biology. Volume 22, Number 7, July 2012, pp. 381-389, doi : 10.1016 / j.tcb.2012.04.007 , PMID 22613354 .
  14. RG Parton, MA del Pozo: Caveolae as plasma membrane sensors, protectors and organizers. In: Nature reviews. Molecular cell biology. Volume 14, Number 2, February 2013, pp. 98-112, doi : 10.1038 / nrm3512 , PMID 23340574 .
  15. A. Echarri, MA Del Pozo: Caveolae - mechanosensitive membrane invaginations linked to actin filaments. In: Journal of cell science. Volume 128, Number 15, August 2015, pp. 2747-2758, doi : 10.1242 / jcs.153940 , PMID 26159735 .
  16. a b S. A. Freeman, S. Grinstein: Phagocytosis: receptors, signal integration, and the cytoskeleton. In: Immunological reviews. Volume 262, Number 1, November 2014, pp. 193-215, doi : 10.1111 / imr.12212 , PMID 25319336 .
  17. J. Moretti, JM Blander: Insights into phagocytosis-coupled activation of pattern recognition receptors and inflammasomes. In: Current opinion in immunology. Volume 26, February 2014, pp. 100–110, doi : 10.1016 / j.coi.2013.11.003 , PMID 24556406 , PMC 3932007 (free full text).
  18. ^ R. Levin, S. Grinstein, D. Schlam: Phosphoinositides in phagocytosis and macropinocytosis. In: Biochimica et Biophysica Acta . Volume 1851, Number 6, June 2015, pp. 805-823, doi : 10.1016 / j.bbalip.2014.09.005 , PMID 25238964 .
  19. Jump up J. Fric, T. Zelante, P. Ricciardi-Castagnoli: Phagocytosis of Particulate Antigens - All Roads Lead to Calcineurin / NFAT Signaling Pathway. In: Frontiers in immunology. Volume 4, 2014, p. 513, doi : 10.3389 / fimmu.2013.00513 , PMID 24409187 , PMC 3885923 (free full text).
  20. ^ S. Gordon: Phagocytosis: An Immunobiologic Process. In: Immunity. Volume 44, Number 3, March 2016, pp. 463-475, doi : 10.1016 / j.immuni.2016.02.026 , PMID 26982354 .
  21. ^ V. Heinrich: Controlled One-on-One Encounters between Immune Cells and Microbes Reveal Mechanisms of Phagocytosis. In: Biophysical Journal. Volume 109, number 3, August 2015, pp. 469-476, doi : 10.1016 / j.bpj.2015.06.042 , PMID 26244729 , PMC 4572503 (free full text).
  22. ^ S. Arandjelovic, KS Ravichandran: Phagocytosis of apoptotic cells in homeostasis. In: Nature immunology. Volume 16, Number 9, September 2015, pp. 907-917, doi : 10.1038 / ni.3253 , PMID 26287597 .