Kai Simons

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Kai Simons
Prof Kai Simons 2014 (cropped).jpg
Born
Helsinki, Finland
Nationality Finnish
Education University of Helsinki (MD), Rockefeller University (postdoctoral fellowship)
Known for lipid rafts, trans-Golgi network
SpouseCarola Simons
Children3; Mikael, Katja, Matias
Scientific career
Fields biochemistry, cell biology
Institutions Rockefeller University, University of Helsinki, EMBL, MPI-CBG, Lipotype GmbH
Academic advisorsLennard Philipson, John Tooze, James Watson, Linus Pauling
Website http://www.lipotype.com

Kai Simons is a Finnish professor of biochemistry and cell biology and physician, living and working in Germany. He introduced the concept of lipid rafts, and coined the term trans-Golgi network . He is the co-founder and co-organizer of the European Molecular Biology Laboratory and European Molecular Biology Organization, and initiated the foundation of Max Planck Institute of Molecular Cell Biology and Genetics.

Contents

Early life and education

Kai Simons is the son of a physics professor. His father convinced him to study medicine, though he originally wanted to study physics. [1] While studying at the University of Helsinki, Simons spent a summer internship in the Stockholm laboratory of Bengt Samuelsson [2] There, he studied mechanisms of vitamin B12 absorption. [1] He worked with other students to organize a campaign to fight taeniasis, a disease common in eastern Finland where eating raw fish is popular. [2]

After completing his MD in 1964, he began a postdoctoral fellowship at Rockefeller University in New York City, where he worked between 1966 and 1967 on blood serum protein polymorphism. [1]

Career

Simons returned to Helsinki in 1967, where he began working as a junior investigator for the Finnish Medical Research Council at the University of Helsinki. [2] [3] He became a group leader in 1972 and was a biochemistry professor in 1971–79 at the medical faculty of this university [3] At first, he continued his work on serum proteins. Next, together with Leevi Kääriäinen and Ossi Renkonen, he started a research team – later joined by Ari Helenius, his first PhD student and later a post doctoral researcher who became Simons' brother-in-law. After a one-month stay in MRC Laboratory for Molecular Biology in Cambridge, the group started investigating a Semliki Forest virus, introduced to Simons by Kääriäinen. [1]

In 1975 Simons went to Heidelberg, Germany, as one of the EMBL group leaders. Together with Ari Helenius he helped to develop EMBL, headed at this time by John Kendrew. [1] In years 1982–1998 Simons was a coordinator of the Cell Biology Program there. [3] During this time he for the first time he introduced the concept of lipid rafts, [4] as well as coined the term trans-Golgi network and proposed its role in protein and lipid sorting. [5]

In 1999 he took part in setting up ELSO (later incorporated into EMBO), which later he presided over. [6]

He was one of the initiators of establishing and building Max Planck Institute of Molecular Cell Biology and Genetics in Dresden (Germany), where he moved. Formally from 1998 (beginning of MPI-CBG construction) and from 2000 he was one of five institute's directors and also a group leader there. [1] He was a director (1998–2006) and a group leader (until 2012). [7] [8] Since 2006 he is a "director emeritus". [7]

He is the co-founder and co-owner of Lipotype GmbH. [9] >

In 2012 he started-up a biotech company Lipotype GmbH, where he is a CEO. [9]

Research

Early in his career, Simons pursued research in the field of medical biochemistry. Both his master's thesis and postgraduate research focused on vitamin B12 absorption. [1] [10] [11] After returning from his post-doc scholarship he continued research on vitamin B12 as well as on blood plasma proteins, but soon started investigating Semliki Forest virus, focusing on its membrane and its lipid composition and their role in the virus budding and its transport, as the model for lipid and protein secretion. [1] [12] [13] [14] [15] During this period, Simons also investigated the application of detergents in biochemistry with a special attention to their role in biological membrane research. [16]

The virus lifecycle and how it uses components of vesicular pathways while shuttling to the cell surface, turned Simons' attention toward vesicular transport pathways and cell polarization. Applying epithelial model cells – MDCK (Madin-Darby canine kidney), he investigated lipid transport, protein sorting and their role in polarizing cells. [1] [17] [18]

In these studies, he described the role of the trans-Golgi network (TGN) in protein and lipid sorting according to their destination. [5] [1] In his works from 1988, together with Gerit van Meer, [19] [20] Simons proposed the existence of lipid microdomains in cell membranes for the first time. [1] Such microdomains differ in their composition from the surrounding membrane and have special functions. Simons coined the term 'lipid rafts' to describe these microdomains. This concept was developed over the years to be presented more fully in 1997 in Nature journal by Simons and Ikonen. [4] This paper became one of the most frequently cited works in the field of membrane research. Other Simons' paper, on role of lipid rafts in the signal transduction [21] is second highest cited work and Simons is fourth highest cited scientist in the field of signal transduction. Kai Simons was also recognized by ISI Web of Knowledge, as one of the most cited scientist ever.

In subsequent years, Simons continued to work on the role of lipid rafts, and more generally lipids, in cell polarization and protein sorting. [22] He was interested also in the role of lipids and protein sorting in neurodegenerative diseases, especially in Alzheimer's disease. [23] [24]

His scientific record includes more than 350 scientific articles, mostly in the field of biochemistry, molecular organization of the cell, and biochemistry and physiology of a cell membrane.

Considering his work from years 1996–2007 tracked until May 2009, Simons was 12. in the list of the most frequently cited scientists in the field cell biology with 90 articles and 16,299 citations. [25]

Honours and awards

Kai Simons honours and awards include: [3] [26]

Kai Simons was and is also a member of numerous societies, committees and organisations, as well as an editor for several scientific journals. [3]

Personal life

He is married to Carola Simons and a father of three. [2]

Related Research Articles

<span class="mw-page-title-main">Endomembrane system</span> Membranes in the cytoplasm of a eukaryotic cell

The endomembrane system is composed of the different membranes (endomembranes) that are suspended in the cytoplasm within a eukaryotic cell. These membranes divide the cell into functional and structural compartments, or organelles. In eukaryotes the organelles of the endomembrane system include: the nuclear membrane, the endoplasmic reticulum, the Golgi apparatus, lysosomes, vesicles, endosomes, and plasma (cell) membrane among others. The system is defined more accurately as the set of membranes that forms a single functional and developmental unit, either being connected directly, or exchanging material through vesicle transport. Importantly, the endomembrane system does not include the membranes of plastids or mitochondria, but might have evolved partially from the actions of the latter.

<span class="mw-page-title-main">Endocytosis</span> Cellular process

Endocytosis is a cellular process in which substances are brought into the cell. The material to be internalized is surrounded by an area of cell membrane, which then buds off inside the cell to form a vesicle containing the ingested materials. Endocytosis includes pinocytosis and phagocytosis. It is a form of active transport.

<span class="mw-page-title-main">Vesicle (biology and chemistry)</span> Any small, fluid-filled, spherical organelle enclosed by a membrane

In cell biology, a vesicle is a structure within or outside a cell, consisting of liquid or cytoplasm enclosed by a lipid bilayer. Vesicles form naturally during the processes of secretion (exocytosis), uptake (endocytosis), and the transport of materials within the plasma membrane. Alternatively, they may be prepared artificially, in which case they are called liposomes. If there is only one phospholipid bilayer, the vesicles are called unilamellar liposomes; otherwise they are called multilamellar liposomes. The membrane enclosing the vesicle is also a lamellar phase, similar to that of the plasma membrane, and intracellular vesicles can fuse with the plasma membrane to release their contents outside the cell. Vesicles can also fuse with other organelles within the cell. A vesicle released from the cell is known as an extracellular vesicle.

<span class="mw-page-title-main">Lipid-anchored protein</span> Membrane protein

Lipid-anchored proteins are proteins located on the surface of the cell membrane that are covalently attached to lipids embedded within the cell membrane. These proteins insert and assume a place in the bilayer structure of the membrane alongside the similar fatty acid tails. The lipid-anchored protein can be located on either side of the cell membrane. Thus, the lipid serves to anchor the protein to the cell membrane. They are a type of proteolipids.

In biology, caveolae, which are a special type of lipid raft, are small invaginations of the plasma membrane in the cells of many vertebrates. They are the most abundant surface feature of many vertebrate cell types, especially endothelial cells, adipocytes and embryonic notochord cells. They were originally discovered by E. Yamada in 1955.

<span class="mw-page-title-main">Oligosaccharide</span> Saccharide polymer

An oligosaccharide is a saccharide polymer containing a small number of monosaccharides. Oligosaccharides can have many functions including cell recognition and cell adhesion.

<span class="mw-page-title-main">Endosome</span> Vacuole to which materials ingested by endocytosis are delivered

Endosomes are a collection of intracellular sorting organelles in eukaryotic cells. They are parts of the endocytic membrane transport pathway originating from the trans Golgi network. Molecules or ligands internalized from the plasma membrane can follow this pathway all the way to lysosomes for degradation or can be recycled back to the cell membrane in the endocytic cycle. Molecules are also transported to endosomes from the trans Golgi network and either continue to lysosomes or recycle back to the Golgi apparatus.

<span class="mw-page-title-main">Lipid raft</span> Combination in the membranes of cells

The plasma membranes of cells contain combinations of glycosphingolipids, cholesterol and protein receptors organised in glycolipoprotein lipid microdomains termed lipid rafts. Their existence in cellular membranes remains controversial. Indeed, Kervin and Overduin imply that lipid rafts are misconstrued protein islands, which they propose form through a proteolipid code. Nonetheless, it has been proposed that they are specialized membrane microdomains which compartmentalize cellular processes by serving as organising centers for the assembly of signaling molecules, allowing a closer interaction of protein receptors and their effectors to promote kinetically favorable interactions necessary for the signal transduction. Lipid rafts influence membrane fluidity and membrane protein trafficking, thereby regulating neurotransmission and receptor trafficking. Lipid rafts are more ordered and tightly packed than the surrounding bilayer, but float freely within the membrane bilayer. Although more common in the cell membrane, lipid rafts have also been reported in other parts of the cell, such as the Golgi apparatus and lysosomes.

<span class="mw-page-title-main">Sphingomyelin</span> Class of chemical compounds

Sphingomyelin is a type of sphingolipid found in animal cell membranes, especially in the membranous myelin sheath that surrounds some nerve cell axons. It usually consists of phosphocholine and ceramide, or a phosphoethanolamine head group; therefore, sphingomyelins can also be classified as sphingophospholipids. In humans, SPH represents ~85% of all sphingolipids, and typically make up 10–20 mol % of plasma membrane lipids.

<i>Semliki Forest virus</i> Species of virus

The Semliki Forest virus is an alphavirus found in central, eastern, and southern Africa. It was first isolated from mosquitoes in the Semliki Forest, Uganda by the Uganda Virus Research Institute in 1942 and described by Smithburn and Haddow. It is known to cause disease in animals and humans.

<span class="mw-page-title-main">Max Planck Institute of Molecular Cell Biology and Genetics</span> Research institute in Germany

The Max Planck Institute of Molecular Cell Biology and Genetics (MPI-CBG) is a biology research institute located in Dresden, Germany. It was founded in 1998 and was fully operational in 2001. Research groups in the institute work in molecular biology, cell biology, developmental biology, biophysics, systems biology, and mathematics supported by various facilities.

Phospholipase D (EC 3.1.4.4, lipophosphodiesterase II, lecithinase D, choline phosphatase, PLD; systematic name phosphatidylcholine phosphatidohydrolase) is an enzyme of the phospholipase superfamily that catalyses the following reaction

<span class="mw-page-title-main">Vesicular transport adaptor protein</span>

Vesicular transport adaptor proteins are proteins involved in forming complexes that function in the trafficking of molecules from one subcellular location to another. These complexes concentrate the correct cargo molecules in vesicles that bud or extrude off of one organelle and travel to another location, where the cargo is delivered. While some of the details of how these adaptor proteins achieve their trafficking specificity has been worked out, there is still much to be learned.

<span class="mw-page-title-main">Monensin</span> Chemical compound

Monensin is a polyether antibiotic isolated from Streptomyces cinnamonensis. It is widely used in ruminant animal feeds.

<span class="mw-page-title-main">PI4KB</span> Protein-coding gene in the species Homo sapiens

Phosphatidylinositol 4-kinase beta is an enzyme that in humans is encoded by the PI4KB gene.

<span class="mw-page-title-main">VAPA</span> Protein-coding gene in humans

VAMP-Associated Protein A is a protein that in humans is encoded by the VAPA gene. Together with VAPB and VAPC it forms the VAP protein family. They are integral endoplasmic reticulum membrane proteins of the type II and are ubiquitous among eukaryotes.

<span class="mw-page-title-main">Scott D. Emr</span> American cell biologist

Scott D. Emr is an American cell biologist and the founding and current Director of the Weill Institute for Cell and Molecular Biology at Cornell University, where he is also a Frank H.T. Rhodes Class of 1956 Professor at the Department of Molecular Biology and Genetics.

Hydrophobic mismatch is the difference between the thicknesses of hydrophobic regions of a transmembrane protein and of the biological membrane it spans. In order to avoid unfavorable exposure of hydrophobic surfaces to water, the hydrophobic regions of transmembrane proteins are expected to have approximately the same thickness as the hydrophobic region of the surrounding lipid bilayer. Nevertheless, the same membrane protein can be encountered in bilayers of different thickness. In eukaryotic cells, the plasma membrane is thicker than the membranes of the endoplasmic reticulum. Yet all proteins that are abundant in the plasma membrane are initially integrated into the endoplasmic reticulum upon synthesis on ribosomes. Transmembrane peptides or proteins and surrounding lipids can adapt to the hydrophobic mismatch by different means.

<span class="mw-page-title-main">Sec14</span>

Sec14 is a cytosolic protein found in yeast which plays a role in the regulation of several cellular functions, specifically those related to intracellular transport. Encoded by the Sec14 gene, Sec14p may transport phosphatidylinositol and phosphatidylcholine produced in the endoplasmic reticulum and the Golgi body to other cellular membranes. Additionally, Sec14p potentially plays a role in the localization of lipid raft proteins. Sec14p is an essential gene in yeast, and is homologous in function to phosphatidylinositol transfer protein in mammals. A conditional mutant with non-functional Sec14p presents with Berkeley bodies and deficiencies in protein secretion.

<span class="mw-page-title-main">Cell membrane</span> Biological membrane that separates the interior of a cell from its outside environment

The cell membrane is a biological membrane that separates and protects the interior of a cell from the outside environment. The cell membrane consists of a lipid bilayer, made up of two layers of phospholipids with cholesterols interspersed between them, maintaining appropriate membrane fluidity at various temperatures. The membrane also contains membrane proteins, including integral proteins that span the membrane and serve as membrane transporters, and peripheral proteins that loosely attach to the outer (peripheral) side of the cell membrane, acting as enzymes to facilitate interaction with the cell's environment. Glycolipids embedded in the outer lipid layer serve a similar purpose.

References

  1. 1 2 3 4 5 6 7 8 9 10 11 Simons, Kai (29 December 2008). "Kai Simons: membrane master". The Journal of Cell Biology. 183 (7): 1180–1181. doi:10.1083/jcb.1837pi. ISSN   1540-8140. PMC   2606959 . PMID   19114590.
  2. 1 2 3 4 "ASCB Members Profile Archives – Kai Simons". The American Society for Cell Biology. 13 August 2009. Archived from the original on 15 July 2007. Retrieved 27 July 2016.
  3. 1 2 3 4 5 "Kai Simons". MPI CBG Research Group -: Group Leader. Max Planck Institute of Molecular Cell Biology and Genetics. Archived from the original on 27 September 2016. Retrieved 28 July 2016.
  4. 1 2 Simons K, Ikonen E (1997). "Functional rafts in cell membranes". Nature. 387 (6633): 569–72. Bibcode:1997Natur.387..569S. doi:10.1038/42408. PMID   9177342. S2CID   4359503.
  5. 1 2 Griffiths G, Simons K (1986). "The trans Golgi network: sorting at the exit site of the Golgi complex". Science. 234 (4775): 438–43. Bibcode:1986Sci...234..438G. doi:10.1126/science.2945253. PMID   2945253.
  6. ↑ Gransalke, Kathleen (2014). "There Are No Easy Solutions" (PDF). Lab Times. 4: 34–37. ISSN   1864-2381. Archived from the original (PDF) on 6 August 2016. Retrieved 27 July 2016.
  7. 1 2 "MPI-CBG: Directors". Max Planck Institute of Molecular Cell Biology and Genetics. Retrieved 26 July 2016.
  8. ↑ "MPI-CBG: Alumni". Max Planck Institute of Molecular Cell Biology and Genetics. Retrieved 26 July 2016.
  9. 1 2 "Everything you should know ABOUT US". Lipotype GmbH. Retrieved 26 July 2016.
  10. ↑ Grasbeck, R.; Runeberg, L.; Simons, K. (12 December 1959). "Intrinsic factor and radiovitamin B12 excretion in rats". Acta Physiologica Scandinavica. 47: 370–374. ISSN   0001-6772. PMID   13828995.
  11. ↑ Grasbeck, R.; Simons, K.; Sinkkonen, I. (1 January 1962). "Purification of intrinsic factor and vitamin B12 binders from human gastric juice". Annales Medicinae Experimentalis et Biologiae Fenniae. 40(Suppl 6): 1–24. ISSN   0003-4479. PMID   13949889.
  12. ↑ Renkonen O, Gahmberg CG, Kaariainen L, Simons K (1972). "Envelope of Semliki Forest virus as membrane model". Biochem. J. 128 (1): 20P–21P. doi:10.1042/bj1280020pb. PMC   1173622 . PMID   5085567.
  13. ↑ Renkonen O, Kääriäinen L, Gahmberg CG, Simons K (1972). "Lipids of Semliki Forest virus and of host cell membranes". Biochem. Soc. Symp. (35): 407–22. PMID   4614812.
  14. ↑ Simons K, Garoff H (1980). "The budding mechanisms of enveloped animal viruses". J. Gen. Virol. 50 (1): 1–21. doi: 10.1099/0022-1317-50-1-1 . PMID   6255080.
  15. ↑ Simons K, Warren G (1984). "Semliki Forest virus: a probe for membrane traffic in the animal cell". Adv. Protein Chem. Advances in Protein Chemistry. 36: 79–132. doi:10.1016/S0065-3233(08)60296-X. ISBN   9780120342365. PMC   7173159 . PMID   6382965.
  16. ↑ Helenius A, Simons K (1975). "Solubilization of membranes by detergents". Biochim. Biophys. Acta. 415 (1): 29–79. doi:10.1016/0304-4157(75)90016-7. PMID   1091302.
  17. ↑ Simons K, Fuller SD (1985). "Cell surface polarity in epithelia". Annu. Rev. Cell Biol. 1: 243–88. doi:10.1146/annurev.cb.01.110185.001331. PMID   3939606.
  18. ↑ Simons K (1987). "Membrane traffic in an epithelial cell line derived from the dog kidney". Kidney Int. Suppl. 23: S201–10. PMID   2831424.
  19. ↑ van Meer G, Simons K (1988). "Lipid polarity and sorting in epithelial cells". J. Cell. Biochem. 36 (1): 51–8. doi:10.1002/jcb.240360106. hdl: 1874/294292 . PMID   3277985. S2CID   32086669.
  20. ↑ Simons K, van Meer G (1988). "Lipid sorting in epithelial cells". Biochemistry. 27 (17): 6197–202. doi:10.1021/bi00417a001. hdl: 1874/293951 . PMID   3064805.
  21. ↑ Simons, K.; Toomre, D. (1 October 2000). "Lipid rafts and signal transduction". Nature Reviews. Molecular Cell Biology. 1 (1): 31–39. doi:10.1038/35036052. ISSN   1471-0072. PMID   11413487. S2CID   10914632.
  22. ↑ Klemm, Robin W.; Ejsing, Christer S.; Surma, Michal A.; Kaiser, Hermann-Josef; Gerl, Mathias J.; Sampaio, Julio L.; de Robillard, Quentin; Ferguson, Charles; Proszynski, Tomasz J. (18 May 2009). "Segregation of sphingolipids and sterols during formation of secretory vesicles at the trans-Golgi network" (PDF). The Journal of Cell Biology. 185 (4): 601–612. doi:10.1083/jcb.200901145. ISSN   1540-8140. PMC   2711577 . PMID   19433450.
  23. ↑ Rajendran, Lawrence; Honsho, Masanori; Zahn, Tobias R.; Keller, Patrick; Geiger, Kathrin D.; Verkade, Paul; Simons, Kai (25 July 2006). "Alzheimer's disease beta-amyloid peptides are released in association with exosomes". Proceedings of the National Academy of Sciences of the United States of America. 103 (30): 11172–11177. Bibcode:2006PNAS..10311172R. doi: 10.1073/pnas.0603838103 . ISSN   0027-8424. PMC   1544060 . PMID   16837572.
  24. ↑ Rajendran, Lawrence; Schneider, Anja; Schlechtingen, Georg; Weidlich, Sebastian; Ries, Jonas; Braxmeier, Tobias; Schwille, Petra; Schulz, Jörg B.; Schroeder, Cornelia (25 April 2008). "Efficient inhibition of the Alzheimer's disease beta-secretase by membrane targeting". Science. 320 (5875): 520–523. Bibcode:2008Sci...320..520R. doi:10.1126/science.1156609. ISSN   1095-9203. PMID   18436784. S2CID   5500387.
  25. ↑ Neumann, Ralf (2009). "Publication Analysis 1996–2007. Cell Biology" (PDF). Lab Times. 5: 42–44. ISSN   1864-2381 . Retrieved 27 July 2016.
  26. ↑ "Academy of Europe: Simons, Kai". Academia Europaea. Retrieved 26 July 2016.
  27. ↑ "Kai Simons. Robert Koch Gold Medal 2016". Robert Koch Gold Medal 2016. Robert-Koch-Stiftung. 2016. Retrieved 26 July 2016.
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