Meisosomes, folded membrane platforms, link the epidermis to the cuticle in C. elegans

Abstract

AbstractApical extracellular matrices (aECMs) form a physical barrier to the environment. In C. elegans, the epidermal aECM is the cuticle, composed mainly of different types of collagen, associated in circumferential ridges separated by furrows. Damage to the cuticle causes stress responses in the underlying epidermis by a process that is poorly understood. Here, we focus on structures connecting the cuticle to the epidermis, that we term “meisosomes”. We show that meisosomes are composed of stacked parallel folds of the epidermal plasma membrane, filled with cuticle. Before moulting, meisosomes align with the underlying cytoskeleton in between furrows. In mutants lacking furrows, that exhibit a constitutive damage response in the epidermis, meisosomes are smaller and fail to align. A loss of connection between the epidermis and the cuticle is also observed in these mutants, as well as a modification of the biomechanical properties of the skin. Meisosomes are therefore an essential component of the skin, serving as attachment platforms between the cuticle and epidermis. They could also be involved in relaying tensile information from the cuticle to the underlying epidermis as part of an integrated stress response to injury and infection.