CUTI-1: A Novel Tetraspan Protein Involved in C. elegans CUTicle Formation and Epithelial Integrity

Julie-Anne Fritz,Carolyn A Behm

doi:10.1371/journal.pone.0005117

Abstract

The nematode cuticle is a tough extracellular matrix composed primarily of cross-linked collagens and non-collagenous cuticulins. It is required for nematode motility and protection from the external environment. Little is known about how the complex process of cuticle formation has been adapted to the specialized requirements of the nematode cuticle, which is structurally and compositionally unique from other organisms. The C. elegans gene cuti-1 (CUTicle and epithelial Integrity) encodes a nematode-specific protein. We have shown that CUTI-1 is expressed in the epithelia and in seam cells. Within these tissues the expression of cuti-1 mRNA cycles throughout development in line with the molting cycle, a process that involves synthesis of a new cuticle. In addition, knockdown of cuti-1 by RNA interference (RNAi) results in worms that display post-embryonic phenotypes related to cuticle dysfunction and defects in epithelial integrity. This is one of the first reports of a nematode-specific protein involved in extracellular matrix formation. It provides further insight into how novel ways have evolved to regulate the formation of the cuticle, which is the primary protective barrier and skeletal component of nematodes.

Highlights

The cuticle of the free-living nematode, Caenorhabditis elegans, is a tough extracellular matrix (ECM) composed primarily of crosslinked collagens and non-collagenous cuticulins [1,2,3]
We have demonstrated that CUTI-1 plays an important role in formation of the nematode cuticle
Consistent with this, CUTI-1 is present in the hypodermis and seam cells, the main sites of cuticle synthesis

Summary

Introduction

The cuticle of the free-living nematode, Caenorhabditis elegans, is a tough extracellular matrix (ECM) composed primarily of crosslinked collagens and non-collagenous cuticulins [1,2,3] It is important for providing body form to the worm and protecting it from the external environment. The first cuticle is laid down during embryogenesis and re-synthesized underneath the old cuticle at each of the four larval molts During this time, the seam cells, and to a lesser extent the hypodermal cells, accumulate large Golgi bodies and vesicles containing densely packed material. The seam cells, and to a lesser extent the hypodermal cells, accumulate large Golgi bodies and vesicles containing densely packed material This is consistent with high levels of protein synthesis [6]. Consistent with the cyclical nature of cuticle formation and molting, the rate of synthesis of cuticular components and proteins involved in the assembly of the cuticle is high prior to molting and low between molts [8]

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Conclusion