Publicação
Exploring the role of O-Mannosylation in the modulation of E-Cadherin function in Gastric Cancer cell line models
| Resumo: | The establishment of stable adherens junctions by the action of the E-Cadherin (E-Cad)-catenins complex is essential for epithelial tissue architecture and mechanical integrity, contributing effectively for tumor suppression. Therefore, E-Cad impairment is often associated with loss of adhesive properties of epithelial cells, invasiveness and metastasis. As E-Cad is a glycoprotein, it can be modified by N- and O-glycans, specifically O-mannose (O-Man) glycans. N-glycosylation and O-mannosylation initiate at the endoplasmic reticulum (ER), carry on in the Golgi compartment, and terminate when the glycoprotein is released to the cytoplasm or liberated in vesicles for the cellular membrane. The initial monosaccharide residues can be further extended in the several compartments of the Golgi apparatus by the action of several glycosyltransferases: in the case of N-glycosylation, N-acetylglucosamyniltransferases (GnTs) III and V (GnT-III and GnT-V) are often involved in the modification of the glycan structure by the addition of a bisecting N-acetylglucosamine (GlcNAc) or β-1,6 GlcNAc branching residue, respectively. While the formation of bisecting GlcNAc N-glycans by GnT-III has been proven to be tumor suppressor, high levels of β-1,6 GlcNAc branching N-glycans formed by the action of GnT-V are usually associated with highly metastatic tumors. Work by our group allowed us to describe the impact of the activity of these two enzymes in E-Cad expression and regulation, specifically in a gastric cancer (GC) context that cannot be explained solely by genetic or epigenetic alterations. Recently, O-mannosylation gained interest relating to E-Cad, as it was described that E-Cad presents several available O-mannosylation sites, and that the O-Man glycans present on E-Cad contribute to its biological functions, namely cell-cell adhesion. This work aims to understand how O-mannosylation modulates E-Cad functions in tumor development and progression, and to figure out the interplay between O-mannosylation and N-glycosylation in this context. Our results clearly indicate that the gaining of differentiation status of a cell line is accompanied by an increase in the cellular overall O-mannosylation profile, and that E-Cad presents higher levels of O-Man glycans attached to it in that case. On the other hand, we observed that the increase in O-Man glycans and the decrease of branched GlcNAc N-glycans attached to E-Cad is related to a more stable phenotype. These results support the idea that O-mannosylation of E-Cad is essential for its biological functions, and that the absence of this post-translational modification (PTM) may be one of the key elements for the impairment of this glycoprotein, which leads to tumor development and progression. Globally, the main goal of this project is to further clarify the molecular mechanisms behind E-Cad dysfunction in GC that are important in the setting up of human adenocarcinomas, having in mind potential new applications in the clinic. The work that is present here was developed as part of a comprehensive project that aims to explore the O-mannosylation profile of E-Cadherin in Gastric Cancer, carried out by me and Sandra Carvalho (PhD Student that co-supervised this work), which will culminate in the preparation of a manuscript to be submitted for publication. |
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| Autores principais: | Oliveira, Tiago Manuel Fontes |
| Assunto: | Ciências Médicas::Outras Ciências Médicas Ciências Naturais::Ciências Biológicas |
| Ano: | 2015 |
| País: | Portugal |
| Tipo de documento: | dissertação de mestrado |
| Tipo de acesso: | acesso aberto |
| Instituição associada: | Universidade do Minho |
| Idioma: | inglês |
| Origem: | RepositóriUM - Universidade do Minho |
| Resumo: | The establishment of stable adherens junctions by the action of the E-Cadherin (E-Cad)-catenins complex is essential for epithelial tissue architecture and mechanical integrity, contributing effectively for tumor suppression. Therefore, E-Cad impairment is often associated with loss of adhesive properties of epithelial cells, invasiveness and metastasis. As E-Cad is a glycoprotein, it can be modified by N- and O-glycans, specifically O-mannose (O-Man) glycans. N-glycosylation and O-mannosylation initiate at the endoplasmic reticulum (ER), carry on in the Golgi compartment, and terminate when the glycoprotein is released to the cytoplasm or liberated in vesicles for the cellular membrane. The initial monosaccharide residues can be further extended in the several compartments of the Golgi apparatus by the action of several glycosyltransferases: in the case of N-glycosylation, N-acetylglucosamyniltransferases (GnTs) III and V (GnT-III and GnT-V) are often involved in the modification of the glycan structure by the addition of a bisecting N-acetylglucosamine (GlcNAc) or β-1,6 GlcNAc branching residue, respectively. While the formation of bisecting GlcNAc N-glycans by GnT-III has been proven to be tumor suppressor, high levels of β-1,6 GlcNAc branching N-glycans formed by the action of GnT-V are usually associated with highly metastatic tumors. Work by our group allowed us to describe the impact of the activity of these two enzymes in E-Cad expression and regulation, specifically in a gastric cancer (GC) context that cannot be explained solely by genetic or epigenetic alterations. Recently, O-mannosylation gained interest relating to E-Cad, as it was described that E-Cad presents several available O-mannosylation sites, and that the O-Man glycans present on E-Cad contribute to its biological functions, namely cell-cell adhesion. This work aims to understand how O-mannosylation modulates E-Cad functions in tumor development and progression, and to figure out the interplay between O-mannosylation and N-glycosylation in this context. Our results clearly indicate that the gaining of differentiation status of a cell line is accompanied by an increase in the cellular overall O-mannosylation profile, and that E-Cad presents higher levels of O-Man glycans attached to it in that case. On the other hand, we observed that the increase in O-Man glycans and the decrease of branched GlcNAc N-glycans attached to E-Cad is related to a more stable phenotype. These results support the idea that O-mannosylation of E-Cad is essential for its biological functions, and that the absence of this post-translational modification (PTM) may be one of the key elements for the impairment of this glycoprotein, which leads to tumor development and progression. Globally, the main goal of this project is to further clarify the molecular mechanisms behind E-Cad dysfunction in GC that are important in the setting up of human adenocarcinomas, having in mind potential new applications in the clinic. The work that is present here was developed as part of a comprehensive project that aims to explore the O-mannosylation profile of E-Cadherin in Gastric Cancer, carried out by me and Sandra Carvalho (PhD Student that co-supervised this work), which will culminate in the preparation of a manuscript to be submitted for publication. |
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