The Extracellular Matrix in the Evolution of Cortical Development and Folding.

Víctor Borrell,Salma Amin

doi:10.3389/fcell.2020.604448

Abstract

The evolution of the mammalian cerebral cortex leading to humans involved a remarkable sophistication of developmental mechanisms. Specific adaptations of progenitor cell proliferation and neuronal migration mechanisms have been proposed to play major roles in this evolution of neocortical development. One of the central elements influencing neocortex development is the extracellular matrix (ECM). The ECM provides both a structural framework during tissue formation and to present signaling molecules to cells, which directly influences cell behavior and movement. Here we review recent advances in the understanding of the role of ECM molecules on progenitor cell proliferation and neuronal migration, and how these contribute to cerebral cortex expansion and folding. We discuss how transcriptomic studies in human, ferret and mouse identify components of ECM as being candidate key players in cortex expansion during development and evolution. Then we focus on recent functional studies showing that ECM components regulate cortical progenitor cell proliferation, neuron migration and the mechanical properties of the developing cortex. Finally, we discuss how these features differ between lissencephalic and gyrencephalic species, and how the molecular evolution of ECM components and their expression profiles may have been fundamental in the emergence and evolution of cortex folding across mammalian phylogeny.

Highlights

The largest part of our brain is the cerebral cortex, or neocortex, which is considered the seat for our higher cognitive abilities and complex reasoning
Recent major breakthroughs in transcriptomic and functional analysis of cortical development in both lissencephalic and gyrencephalic species have identified extracellular matrix (ECM) components as key factors regulating the proliferation of specific types of cortical progenitors, with a direct impact on the expansion and folding of the cerebral cortex (Fietz et al, 2012; Florio and Huttner, 2014; Florio et al, 2017; Long et al, 2018; Long and Huttner, 2019)
By comparing the transcriptomic profile of the cortical germinal zones prospectively forming the Splenial Gyrus and the Lateral Sulcus in the ferret visual cortex, we discovered a large number of genes differentially expressed between these two regions, including genes that encode for cell adhesion molecules and ECM components (De Juan Romero et al, 2015)

Summary

Introduction

The largest part of our brain is the cerebral cortex, or neocortex, which is considered the seat for our higher cognitive abilities and complex reasoning. Recent major breakthroughs in transcriptomic and functional analysis of cortical development in both lissencephalic and gyrencephalic species have identified ECM components as key factors regulating the proliferation of specific types of cortical progenitors, with a direct impact on the expansion and folding of the cerebral cortex (Fietz et al, 2012; Florio and Huttner, 2014; Florio et al, 2017; Long et al, 2018; Long and Huttner, 2019).

Results

Conclusion