Attenuation of N-glycosylation causes polarity and adhesion defects in the C. elegans embryo
1Biozentrum, University of Basel, Klingelbergstrasse 70, Basel CH-4056, Switzerland.
Insights
N-glycosylation impacts cell polarity in C. elegans embryos by affecting cell division size and adhesion. Reduced N-glycosylation disrupts cell-cell adhesion, highlighting its role in maintaining plasma membrane organization.
Area of Science:
- Developmental Biology
- Cell Biology
- Molecular Biology
Background:
- The early Caenorhabditis elegans embryo exhibits high polarization, necessitating the localization of cytoplasmic factors to the plasma membrane.
- This plasma membrane compartmentalization is crucial for the asymmetric distribution of cellular components, influencing daughter cell fates.
- Glycosylation, a common modification of plasma membrane proteins, prompted an investigation into its role in polarity.
Purpose of the Study:
- To investigate the effect of attenuating N-glycosylation on cell polarity establishment and maintenance in the C. elegans early embryo.
- To determine if N-glycosylation influences key aspects of early embryonic development, including cell division, spindle orientation, and cell-cell adhesion.
Main Methods:
- RNA interference (RNAi) was used to reduce N-glycosylation in C. elegans embryos (ribo-1(RNAi)).
- Phenotypic analysis focused on cell size variation during the first cell division, spindle orientation, and cell-cell adhesion at the two-cell stage.
- Genetic manipulation was employed to assess the interplay between polarity establishment factors (e.g., PAR-2) and N-glycosylation's effects.
Main Results:
- While initial polarity establishment remained unaffected, embryos with reduced N-glycosylation showed increased variability in cell size during the first division.
- Defects in spindle orientation were observed in two-cell stage embryos with attenuated N-glycosylation.
- A specific loss of cell-cell adhesion was noted at the two-cell stage, which could be rescued by disrupting polarity establishment.
- Reduced plasma membrane levels of E-cadherin and MAGI-1 were observed and restored when PAR-2 function was absent.
Conclusions:
- N-glycosylation plays a significant role in maintaining plasma membrane compartmentalization and cell polarity in the C. elegans early embryo.
- The findings suggest that N-glycosylation is essential for proper cell-cell adhesion and potentially influences the fidelity of cell division.
- Polarity establishment mechanisms appear to enforce plasma membrane compartmentalization, with N-glycosylation being a key contributor to this process.
Abstract:
The Caenorhabditiselegans early embryo is highly polarized, requiring sequestration of cytoplasmic polarity factors at the plasma membrane. This compartmentalization aids asymmetric distribution of lipids and proteins, which is partially responsible for the fates of the daughter cells. Since most plasma membrane proteins are glycosylated, we determined the effect of attenuation of N-glycosylation on cell polarity. While polarity establishment was not perturbed, the size difference between the two cells formed in first cell division (AB and P1) was more variable in embryos with reduced N-glycosylation than in the mock-treated embryos. In addition, among other deficiencies, we observed spindle orientation defects in two-cell embryos. Moreover, cell-cell adhesion was specifically lost at the two-cell stage when N-glycosylation was reduced. This loss-of-adhesion phenotype was rescued by interfering with polarity establishment, indicating that polarity establishment enforces plasma membrane compartmentalization. Consistent with this idea, the decreased plasma membrane levels of the adhesion proteins E-cadherin and MAGI-1 in ribo-1(RNAi) embryos were restored in the absence of functional PAR-2. Our data suggest a general role for N-glycosylation in plasma membrane compartmentalization and cell polarity.
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