The Caenorhabditis elegans UDP-Glc:glycoprotein glucosyltransferase homologue CeUGGT-2 is an essential protein that does not function as a glycoprotein conformation sensor

BUZZI, LUCILA INÉS; SIMONETTA, SERGIO H.; PARODI, ARMANDO; CASTRO, OLGA A.

Los Angeles

Congreso; 19th International C elegans Meeting; 2013

Genetic Society of America GSA

The UDP-Glc:glycoprotein glucosyltransferase (UGGT) is the key component of the glycoprotein folding quality control mechanism that takes place in the endoplasmic reticulum (ER). It behaves as a sensor of glycoprotein conformation as it exclusively glucosylates glycoproteins not displaying their native conformations. The addition of this glucose residue enables the interaction of folding intermediates with Calnexin/Calreticulin. An enzymatically active UGT is encoded by a single gene in Schizosaccharomyces pombe, Drosophila melanogaster, Trypanosoma cruzi and plants. There are two homologues coding for UGT-like proteins in Euteleostomi and in the genus Caenorhabditis. Both UGGT homologues (HUGT1 and HUGT2) are expressed in human cells, the former but not the latter displayed UGGTactivity and was upregulated under ER stress conditions. Bioinformatics analysis showed that inC.elegans there are two open reading frames (F48E3.3 and F26H9.8 hereinafter referred to as C. elegans uggt-1 and uggt-2 genes respectively) coding for UGGT homologues. .We have previously reported that C. elegans expresses an active UGGT protein localized in the ER (CeUGGT1) that is expressedduring the entire C. elegans life cycle and is upregulated under ER stress. .Here we report that CeUGGT-2 expression is essential for normal development, we analyzed the progenie of the heterozygous uggt-2(ok2510) worms chromosome balanced withhT2 (I; III), a GFP-marked translocation and found that more of 50% of the eggs homozygous uggt-2 deletion mutants arrest development at L1 stage which look very sick. uggt-1 and uggt-2 expresses during the entire nematode life cycle but at very different levels, being uggt-2expression at most 3 % of uggt-1. Depletion of UGGT-1 by RNA interference resulted in a reduced lifespan and that of UGGT-1 and UGGT-2 in a delay in development. We found that both CeUGGT-1 and CeUGGT-2 play a protecting role under ER stress conditions since worms arrested at L2/L3 stages, in conditions that produce the accumulation of unfolded glycoproteins.