Integrin-Linked Kinase (ILK) Plays an Important Role in the Laminin-Dependent Development of Dorsal Root Ganglia during Chicken Embryogenesis

Ewa Mrówczyńska,Antonina Joanna Mazur

doi:10.3390/cells10071666

Abstract

Integrin-linked kinase (ILK) is mainly localized in focal adhesions where it interacts and modulates the downstream signaling of integrins affecting cell migration, adhesion, and survival. The interaction of dorsal root ganglia (DRG) cells, being part of the peripheral nervous system (PNS), with the extracellular matrix (ECM) via integrins is crucial for proper PNS development. A few studies have focused on ILK’s role in PNS development, but none of these have focused on chicken. Therefore, we decided to investigate ILK’s role in the development of Gallus gallus domesticus’s DRG. First, using RT-PCR, Western blotting, and in situ hybridization, we show that ILK is expressed in DRG. Next, by immunocytochemistry, we show ILK’s localization both intracellularly and on the cell membrane of DRG neurons and Schwann cell precursors (SCPs). Finally, we describe ILK’s involvement in multiple aspects of DRG development by performing functional experiments in vitro. IgG-mediated interruption of ILK’s action improved DRG neurite outgrowth, modulated their directionality, stimulated SCPs migration, and impacted growth cone morphology in the presence of laminin-1 or laminin-1 mimicking peptide IKVAV. Taken together, our results show that ILK is important for chicken PNS development, probably via its exposure to the ECM.

Highlights

Dorsal root ganglia (DRG) are indispensable components of the peripheral nervous system (PNS), transferring neural messages from skin, muscles, and internal organs to the spinal cord and brain [1,2]
Considering that laminin-integrin interactions are critical during PNS development and that Integrin-linked kinase (ILK) is associated with integrins, our study aims to deepen the knowledge about ILK’s role in PNS formation at the stage of DRG, as there are still gaps in understanding its function in this area, especially that no work addressing this topic has so far been done in chicken embryos
ILK Is Expressed in Chicken Embryo’s Dorsal Root Ganglia at mRNA and Protein Level, but It Is Not Secreted by DRG Cells

Summary

Introduction

Dorsal root ganglia (DRG) are indispensable components of the peripheral nervous system (PNS), transferring neural messages from skin, muscles, and internal organs to the spinal cord and brain [1,2]. Laminins are large glycoproteins consisting of three chains α, β, and γ, which include various binding sites for the cell receptors [5,6]. They are responsible for the modulation of laminins’ biological activities, such as cell adhesion, growth, differentiation, and migration [7,8,9]. Integrins, being the receptors for ECM proteins, are responsible for the transduction of ECM-cell signals, thereby triggering signal transduction and modulating motility, adhesion, proliferation, differentiation, and survival, which is crucial for proper PNS development [14]. IKVAV, as a laminin-derived peptide, binds directly to the α3β1, α4β1, and α6β1 integrins [15,16]

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