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Howard Riezman

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Howard Riezman
OBJECTIVE
Recent and Selected Publications

Howard Riezman

Howard Riezman received a Ph.D. in Botany from the University of Wisconsin-Madison in 1980 where he studied enyzmes of the glyoxylate cycle with Wayne M. Becker. He worked on mitochondrial biogenesis as a postdoctoral fellow at the Biozentrum of the University of Basel with Gottfried (Jeff) Schatz until 1983, when he became group leader at the Swiss Institute for Experimental Cancer Research (Epalinges, Switzerland). There he pioneered studies of endocytosis in the yeast Saccharomyces cerevisiae. He joined the Biozentrum again in 1988, this time as a Full Professor, and was Biochemistry Division Chairman (1993-1995 and 1999-2001), and Vice-Chairman of the Biozentrum (2000-2001). He continued studies on endocytosis, but also began working on GPI-anchored protein synthesis and transport. He was elected a member of EMBO in 1997. He moved to Geneva in 2002 as a Full Professor. Among his other duties he has served as a member of the Research Council of the Swiss National Science Foundation, Division of Biology and Medicine, from 2001-2008, on several prestigious editorial boards, and is currently chairman of the Biochemistry Department. Howard Riezman received a Ph.D. in Botany from the University of Wisconsin-Madison in 1980 where he studied enyzmes of the glyoxylate cycle with Wayne M. Becker. He worked on mitochondrial biogenesis as a postdoctoral fellow at the Biozentrum of the University of Basel with Gottfried (Jeff) Schatz until 1983, when he became group leader at the Swiss Institute for Experimental Cancer Research (Epalinges, Switzerland). There he pioneered studies of endocytosis in the yeast Saccharomyces cerevisiae. He joined the Biozentrum again in 1988, this time as a Full Professor, and was Biochemistry Division Chairman (1993-1995 and 1999-2001), and Vice-Chairman of the Biozentrum (2000-2001). He continued studies on endocytosis, but also began working on GPI-anchored protein synthesis and transport. He was elected a member of EMBO in 1997. He moved to Geneva in 2002 as a Full Professor. Among his other duties he has served as a member of the Research Council of the Swiss National Science Foundation, Division of Biology and Medicine, from 2001-2008, on several prestigious editorial boards, and is currently chairman of the Biochemistry Department.

OBJECTIVE

Our initial studies focused on the mechanisms of membrane trafficking, in particular, concerning two pathways, endocytosis and GPI-anchored protein transport. We made several important findings in the endocytosis field where we discovered roles for actin, ubiquitination, sphingolipid biosynthesis and sterols. Concerning GPI-anchored protein transport we showed that GPI-anchored proteins are transported from the ER to the Golgi compartment in yeast in different vesicles than many other secretory cargoes. We have developed a unique biochemical assay capable of measuring cargo protein sorting into different vesicle populations. Another important discovery was that ongoing ceramide synthesis is required for ER to Golgi transport of GPI-anchored proteins. Using genetic and biochemical approaches we have found evidence that both sphingolipids and sterols are required for efficient membrane trafficking in yeast and have generated a series of isogenic yeast strains with a variety of sterol and sphingolipid mutations.

We have recently changed our focus somewhat. Our most recent work centers on the role of lipids in cell biology. There is a great heterogeneity of lipid structures. This diversity is not only present among organisms, but between cell types, between organelles within the cell, and between the two leaflets of the lipid bilayer. The reasons behind this heterogeneity and the precise roles of lipids in cells are one of the great open frontiers in cell biology. Our current focus is precisely on these issues. We are using a combination of genetics, biochemistry, lipidomics, genetic engineering and genomics to study this problem. Understanding the roles of lipids in cells will also undoubtedly require interdisciplinary approaches and we are also active on this front and have collaborations with chemists and theoretical physicists. Most of our work uses the yeast, Saccharomyces cerevisiae, because it is an excellent eukaryotic model system to get to the heart of the problem, discovering mechanisms. In addition, we have approaches that have important implications in biotechnology, by modification of yeast lipid composition to make it a suitable host for expression of heterologous proteins and other functions. We also have collaboration with groups working with worms, flies, fish and vertebrates in three continents.

Our current work on lipids centers on sphingolipids and sterols, two lipid classes that are almost exclusively found in eukaryotes and are postulated to be major components of membrane microdomains, called rafts. We have convincing biochemical and genetic evidence that these two lipid classes function together to carry out many cellular functions and are now exploring how they do this. We have several mechanistic leads as well as possible methods to identify the mechanism whereby membranes sense their sterol composition. Our work also has evolutionary implications, predicting that sterols and sphingolipids have co-evolved, which could help to explain the correlative changes in sphingolipid species that are found in kingdoms that have different sterols.

Recent and Selected Publications

>140 total, >9000 citations, average 59.42 citations/article, h-index = 60, use PubMed for a complete listing

Some recent articles, reviews and classics

  • Mukhopadhyay, D. and H. Riezman (2007) Proteasome-independent functions of ubiquitin in endocytosis and signaling. Science, 315, 201-205.
  • Kageyama-Yahara, N. and H. Riezman (2006) Transmembrane topology of ceramide synthase in yeast. Biochem J. 398, 585-593.
  • Grosshans, B.L., H. Grotsch, D. Mukhopadhyay, I.M. Fernandez, J. Pfannstiel, F.Z. Idrissi, J. Lechner, H. Riezman and M.I. Geli (2006) TEDS site phosphorylation of the yeast myosins I is required for ligand-induced but not for constitutive endocytosis of the G protein-coupled receptor Ste2p. J. Biol. Chem. 281, 11104-11114.
  • Meier, K.D., O. Deloche, K. Kajiwara, K. Funato and H. Riezman (2006) Sphingoid base is required for translation initiation during heat stress in Saccharomyces cerevisiae. Mol. Biol. Cell, 17, 1164-1175.
  • Futerman, A. H. and H. Riezman (2005) The ins and outs of Sphingolipid synthesis. Trends Cell Biol. 15, 312-218.
  • Vallée, B. and H. Riezman (2005) Lip1p: a novel subunit of acyl-CoA ceramide synthase. EMBO J., 24, 730-741.
  • Mayor, S. and H. Riezman (2004) Sorting GPI-anchored proteins. Nature Rev. Mol. Cell Biol. 5, 110-120.
  • Funato, K., R. Lombardi, B. Vallée and H. Riezman (2002) Lcb4p is a Key Regulator of Ceramide Synthesis from Exogenous Long Chain Sphingoid Base in Saccharomyces cerevisiae. J. Biol. Chem., 278, 7325-7534.
  • Watanabe, R., K. Funato, K. Venkataraman, A.H. Futerman and H. Riezman (2002) Sphingolipids are required for the stable membrane association of glycosylphosphatidylinositol-anchored proteins in yeast. J. Biol. Chem., 277, 49538-49544.
  • Heese-Peck, A., H. Pichler, B. Zanolari, R. Watanabe, G. Daum, and H. Riezman (2002) Multiple functions of sterols in yeast endocytosis. Mol. Biol. Cell, 13, 2664-2680.
  • Morsomme, P. and H. Riezman (2002) The Rab GTPase Ypt1p and tethering factors couple protein sorting at the ER to vesicle targeting to the Golgi apparatus. Dev. Cell 2, 307-317.
  • Funato, K. and H. Riezman (2001) Vesicular and non-vesicular transport of ceramide from ER to the Golgi apparatus in yeast.
  • Friant, S., R. Lombardi, T. Schmelzle, M.N. Hall, and H. Riezman (2001) Sphingosine signalling via PKH kinases is required for endocytosis in yeast. EMBO J., 20, 6783-6792.
  • Muñiz, M., P. Morsomme, and H. Riezman (2001) Protein sorting upon exit from the endoplasmic reticulum. Cell, 104, 313-320.
  • Zanolari, B., S. Friant, K. Funato, C. Sütterlin, B. J. Stevenson and H. Riezman (2000) Sphingoid base synthesis requirement for endocytosis in Saccharomyces cerevisiae. EMBO J., 19, 2824-2833.
  • Muñiz, M., C. Nuoffer, H.P. Hauri and H. Riezman (2000) The Emp24p complex recruits a specific cargo molecule into ER-derived vesicles. J. Cell Biol., 148, 925-930.
  • Munn, A.L., A. Heese-Peck, B.J. Stevenson, H. Pichler, and H. Riezman (1999) Specific sterols required for the internalization step of endocytosis in yeast. Mol. Biol. Cell, 10, 3943-3957.
  • Geli, M.I. and H. Riezman (1996) Role of myosins I in receptor mediated endocytosis in yeast. Science, 272, 533-535.
  • Hicke, L. and H. Riezman (1996) Ubiquitination of a yeast plasma membrane receptor signals its ligand-stimulated endocytosis. Cell, 84, 277-288.
  • Hamburger, D., M. Egerton and H. Riezman (1995) Yeast Gaa1p is required for attachment of a completed GPI anchor onto proteins. J. Cell Biol., 129, 629-639.
  • Horvath, A., C. Sütterlin, U. Manning-Krieg, N.R. Movva and H. Riezman (1994) Ceramide synthesis enhances transport of GPI-anchored proteins to the Golgi apparatus in yeast. EMBO J. 13, 3687-3695.
  • Munn, A. and H. Riezman (1994) Endocytosis is required for growth of vacuolar acidification-defective yeast. J. Cell Biol., 127, 373-386.
  • Kübler, E., and H. Riezman (1993) Actin and fimbrin are required for the internalization step of endocytosis in yeast. EMBO J. 12, 2855-2862.
  • Riezman, H. (1985) Endocytosis in yeast: Several of the yeast secretory mutants are defective in endocytosis. Cell 40, 1001-1009.
  • Riezman, H., R. Hay, C. Witte, N. Nelson and G. Schatz (1983) Yeast mitochondrial outer membrane specifically binds cytoplasmically-synthesized precursors of mitochondrial proteins. EMBO J. 2, 1113-1118.
  • Riezman, H., E.M. Weir, C.J. Leaver, D.E. Titus and W.M. Becker (1980) Regulation of glyoxysomal enzymes during germination of cucumber. 3. In vitro translation and characterization of four glyoxysomal enzymes. Plant Physiol. 65, 40-46.
  • Kennell, D. and H. Riezman (1977) Transcription and translation initiation frequencies of the Escherichia coli lac operon. J. Mol. Biol. 114, 1-21.
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