Abstract

The long term goals of this proposal are to examine the factors which influence the regulation, structure, and function of enzymes involved in the biosynthesis and catabolism of mammalian N-linked glycans. These enzymes determine the fate of the oligosaccharides on newly synthesized glycoproteins by determining the extent of processing from high mannose- type to complex-type structures. Little is known about the structure or regulation of the enzymes in this pathway. To address these problems the cDNAs encoding several of the processing and catabolic alpha-mannosidases have been isolated and have been organized into two multigene classes. This collection of alpha-mannosidase cDNAs offer several unique experimental systems for the study of the structure, function, and regulation of these enzymes as models for the regulation of glycoprotein biosynthesis and catabolism.
Four specific aims are addressed in this proposal. The first specific aim is to complete the isolation of cDNA and genomic clones encoding the mammalian alpha-mannosidases. The second specific aim is to examine the structure, regulation, and function of the mammalian alpha-mannosidase family members. Heterologous expression, purification, determination of substrate specificity, and determination of in vivo tissue and cell- specific expression patterns will be compared among the enzymes in order to define the respective functions of each of members of the various enzyme classes. Enzymes from mammalian and non-mammalian sources will also be isolated for structure, function, and expression pattern studies. An additional focus of the cloning and sequencing studies on the mannosidases will be the characterization of the molecular basis of human genetic diseases characterized by a deficiency in either Golgi Man II or the lysosomal alpha-mannosidase. This is the third specific aim of the grant. The fourth specific aim will be the generation and characterization of murine models for deficiencies in the various processing and catabolic alpha-mannosidases by murine gene ablation techniques. These mouse knockout models will provide a direct demonstration of the in vivo roles of each of the multi-gene family members and generate an animal model for the eventual testing of therapeutic strategies for the lysosomal storage disease, alpha- mannosidosis.

  Funding Agency

Agency
National Institute of Health (NIH)
Institute
National Institute of General Medical Sciences (NIGMS)
Type
Research Project (R01)
Project #
2R01GM047533-06
Application #
2022582
Study Section
Physiological Chemistry Study Section (PC)
Project Start
1992-05-01
Project End
2001-04-30
Budget Start
1997-05-01
Budget End
1998-04-30
Support Year
6
Fiscal Year
1997
Total Cost
Indirect Cost

  Institution

Name
University of Georgia
Department
Type
Organized Research Units
DUNS #
City
Athens
State
GA
Country
United States
Zip Code
30602

  Publications

Xiang, Yong; Karaveg, Khanita; Moremen, Kelley W (2016) Substrate recognition and catalysis by GH47 ?-mannosidases involved in Asn-linked glycan maturation in the mammalian secretory pathway. Proc Natl Acad Sci U S A 113:E7890-E7899
Zhou, Tao; Frabutt, Dylan A; Moremen, Kelley W et al. (2015) ERManI (Endoplasmic Reticulum Class I ?-Mannosidase) Is Required for HIV-1 Envelope Glycoprotein Degradation via Endoplasmic Reticulum-associated Protein Degradation Pathway. J Biol Chem 290:22184-92
Moremen, Kelley W; Tiemeyer, Michael; Nairn, Alison V (2012) Vertebrate protein glycosylation: diversity, synthesis and function. Nat Rev Mol Cell Biol 13:448-62
Rafiq, Muhammad Arshad; Kuss, Andreas W; Puettmann, Lucia et al. (2011) Mutations in the alpha 1,2-mannosidase gene, MAN1B1, cause autosomal-recessive intellectual disability. Am J Hum Genet 89:176-82
Zhu, Yanping; Suits, Michael D L; Thompson, Andrew J et al. (2010) Mechanistic insights into a Ca2+-dependent family of alpha-mannosidases in a human gut symbiont. Nat Chem Biol 6:125-32
Termine, Daniel J; Moremen, Kelley W; Sifers, Richard N (2009) The mammalian UPR boosts glycoprotein ERAD by suppressing the proteolytic downregulation of ER mannosidase I. J Cell Sci 122:976-84
Zhong, Wei; Kuntz, Douglas A; Ember, Brian et al. (2008) Probing the substrate specificity of Golgi alpha-mannosidase II by use of synthetic oligosaccharides and a catalytic nucleophile mutant. J Am Chem Soc 130:8975-83
Akama, Tomoya O; Nakagawa, Hiroaki; Wong, Nyet Kui et al. (2006) Essential and mutually compensatory roles of {alpha}-mannosidase II and {alpha}-mannosidase IIx in N-glycan processing in vivo in mice. Proc Natl Acad Sci U S A 103:8983-8
Park, Chaeho; Meng, Lu; Stanton, Leslie H et al. (2005) Characterization of a human core-specific lysosomal {alpha}1,6-mannosidase involved in N-glycan catabolism. J Biol Chem 280:37204-16
Moremen, K W; Trimble, R B; Herscovics, A (1994) Glycosidases of the asparagine-linked oligosaccharide processing pathway. Glycobiology 4:113-25

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