Abstract

A distinctive feature of polarized epithelial cells is their specialized junctions, which contribute to cell integrity and provide platforms to orchestrate cell shape changes. This chapter discusses the composition, assembly and remodeling of C. elegans cell-cell (CeAJ) and hemidesmosome-like cell-extracellular matrix junctions (CeHD), proteins that anchor the cytoskeleton, and mechanisms involved in establishing epithelial polarity. Major recent progress in this area has come from the analysis of mechanisms that maintain cell polarity, which involve lipids and trafficking, and on the impact of mechanical forces on junction remodeling. This chapter focuses on cellular, rather than developmental, aspects of epithelial cells.

Highlights

  • Two seemingly opposite features characterize epithelial cells

  • We introduce the actin, intermediate filaments (IFs), and microtubule cytoskeleton and discuss the crosstalk between cell adhesion and cytoskeleton dynamics

  • We introduce the hemidesmosome-like cell-extracellular matrix junctions that provide a link between muscles and the cuticle, and discuss the dynamic aspects of hemidesmosome remodeling

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Summary

Introduction

Two seemingly opposite features characterize epithelial cells On one hand, their cell-cell adhesion junctions organize epithelial tissues as strong barriers; on the other hand, cell-cell junctions need to be remodeled through cytoskeleton-generated forces during embryonic morphogenesis. We introduce the hemidesmosome-like cell-extracellular matrix junctions that provide a link between muscles and the cuticle, and discuss the dynamic aspects of hemidesmosome remodeling. As in Epithelial junctions and attachments, we will focus on cellular aspects of epithelial junctions, and will refer the reader to recent reviews for a more comprehensive discussion of the topic (Zhang and Labouesse, 2010; Baum and Georgiou, 2011; Loveless and Hardin, 2012), to other WormBook chapters for morphogenetic aspects (Epidermal morphogenesis; The C. elegans pharynx: a model for organogenesis; The C. elegans intestine), or for a discussion of extracellular matrix components (Basement membranes; The cuticle). The status of sensory neuron support cells is hybrid, they are often considered as glial (Bacaj et al, 2008), yet they make cell-cell junctions including CeAJ markers discussed below

Approaches and tools to characterize junctional and cytoskeletal components
Establishment and maintenance of epithelial polarity
Establishment of epithelial cell polarity
PAR proteins
Basolateral proteins required for CeAJ compaction and positioning
Junctions and polarity
CeAJ dynamics during the establishment of new contacts
Mechanical tension and the maintenance of CeAJs
Epithelial cytoskeleton
Actin anchoring
Spectrin network
Fibrous organelles resemble hemidesmosomes
Mechanotransduction and the reorganization of CeHDs
Conclusions and future directions
Table 1
10. References
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