title: Altered N-glycosylation modulates TgrB1- and TgrC1-mediated development but not allorecognition in Dictyostelium.
abstract: Cell surface adhesion receptors play diverse functions in multicellular development. In Dictyostelium, two immunoglobulin-like adhesion proteins, TgrB1 and TgrC1, are essential components with dual roles in morphogenesis and allorecognition during development. TgrB1 and TgrC1 form a heterophilic adhesion complex during cell contact and mediate intercellular communication. The underlying signaling pathways, however, have not been characterized. Here, we report on a mutation that suppresses the tgrB-tgrC1-defective developmental arrest. The mutated gene alg9 encodes a putative mannosyl transferase that participates in N-linked protein glycosylation. We show that alteration in N-linked glycosylation, caused by an alg9 mutation with a plasmid insertion (alg9(ins)) or tunicamycin treatment, can partially suppress the developmental phenotypes caused by tgrC1 deletion or replacement with an incompatible allele. The alg9(ins) mutation also preferentially primed cells toward a stalk-cell fate. Despite its effect on development, we found that altered N-linked glycosylation had no discernable effect on TgrB1-TgrC1-mediated allorecognition. Our results show that N-linked protein glycosylation can modulate developmental processes without disturbing cell-cell recognition, suggesting that tgrB1 and tgrC1 have distinct effects in the two processes.
authors.affiliation: Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA.
authors.forename: Cheng-Lin Frank
authors.initials: CL
authors.lastname: Li
authors.affiliation: Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX 77030, USA.
authors.forename: Gong
authors.initials: G
authors.lastname: Chen
authors.affiliation: Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA.
authors.forename: Amanda Nicole
authors.initials: AN
authors.lastname: Webb
authors.affiliation: Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA gadi@bcm.edu.
authors.forename: Gad
authors.initials: G
authors.lastname: Shaulsky
mesh_terms: D004023:Dictyostelium / Q000378:metabolism*; D006031:Glycosylation; D015800:Protozoan Proteins / Q000378:metabolism*; D053773:Transforming Growth Factor beta1 / Q000378:metabolism*
chemical_list: D015800:Protozoan Proteins; D053773:Transforming Growth Factor beta1
keywords: Allorecognition; Development; Dictyostelium; Genetic suppression; N-glycosylation