Lasp-1 Regulates Podosome Function

Miriam Stölting,Vanessa Van Vliet,Stefan Linder,Joachim Kremerskothen,Hermann Pavenstädt,Elke Butt,Christiane Wiesner

doi:10.1371/journal.pone.0035340

Abstract

Eukaryotic cells form a variety of adhesive structures to connect with their environment and to regulate cell motility. In contrast to classical focal adhesions, podosomes, highly dynamic structures of different cell types, are actively engaged in matrix remodelling and degradation. Podosomes are composed of an actin-rich core region surrounded by a ring-like structure containing signalling molecules, motor proteins as well as cytoskeleton-associated proteins.Lasp-1 is a ubiquitously expressed, actin-binding protein that is known to regulate cytoskeleton architecture and cell migration. This multidomain protein is predominantely present at focal adhesions, however, a second pool of Lasp-1 molecules is also found at lamellipodia and vesicle-like microdomains in the cytosol.In this report, we show that Lasp-1 is a novel component and regulator of podosomes. Immunofluorescence studies reveal a localization of Lasp-1 in the podosome ring structure, where it colocalizes with zyxin and vinculin. Life cell imaging experiments demonstrate that Lasp-1 is recruited in early steps of podosome assembly. A siRNA-mediated Lasp-1 knockdown in human macrophages affects podosome dynamics as well as their matrix degradation capacity. In summary, our data indicate that Lasp-1 is a novel component of podosomes and is involved in the regulation of podosomal function.

Highlights

Podosomes are highly dynamic adhesion structures that are constitutively formed in monocytic cells such as macrophages, dendritic cells, or osteoclasts, [1,2,3]
Lasp-1 tagged with the enhanced green fluorescent protein (EGFP-Lasp-1) colocalized with endogenous vinculin at the ring structure of podosomes surrounding the actin core (Fig. 1A)
Similar results were obtained with macrophages encoding vinculin-tagged enhanced yellow fluorescent protein (EYFP) and stained for endogenous Lasp-1 and F-actin (Fig. 1B)

Summary

Introduction

Podosomes are highly dynamic adhesion structures that are constitutively formed in monocytic cells such as macrophages, dendritic cells, or osteoclasts, [1,2,3]. Endothelial cells, smooth muscle cells, as well as glomerular podocytes, have been shown to form podosomes upon stimulation with cytokines, growth factors or phorbol esters [4,5,6,7,8]. Recent studies have shown that the formation of podosomes occurs very rapidly and starts with a clustering of podosome initiation factors. In these cell type a recruitment of the actin polymerization machinery and a later maturation of podosomes occur [11,12,13]

Methods

Results

Conclusion