Lgl1 controls NG2 endocytic pathway to regulate oligodendrocyte differentiation and asymmetric cell division and gliomagenesis

Mathieu Daynac,Jianqin Niu,Claudia K Petritsch,Malek Chouchane,Hannah Y Collins,Nicole E Murphy,Stephen P J Fancy,William B Stallcup,Noemi Andor

doi:10.1038/s41467-018-05099-3

Abstract

Oligodendrocyte progenitor cells (OPC) undergo asymmetric cell division (ACD) to generate one OPC and one differentiating oligodendrocyte (OL) progeny. Loss of pro-mitotic proteoglycan and OPC marker NG2 in the OL progeny is the earliest immunophenotypic change of unknown mechanism that indicates differentiation commitment. Here, we report that expression of the mouse homolog of Drosophila tumor suppressor Lethal giant larvae 1 (Lgl1) is induced during OL differentiation. Lgl1 conditional knockout OPC progeny retain NG2 and show reduced OL differentiation, while undergoing more symmetric self-renewing divisions at the expense of asymmetric divisions. Moreover, Lgl1 and hemizygous Ink4a/Arf knockouts in OPC synergistically induce gliomagenesis. Time lapse and total internal reflection microscopy reveals a critical role for Lgl1 in NG2 endocytic routing and links aberrant NG2 recycling to failed differentiation. These data establish Lgl1 as a suppressor of gliomagenesis and positive regulator of asymmetric division and differentiation in the healthy and demyelinated murine brain.

Highlights

Oligodendrocyte progenitor cells (OPC) undergo asymmetric cell division (ACD) to generate one OPC and one differentiating oligodendrocyte (OL) progeny
We noticed a four-fold increase of lethal giant larvae (Lgl)[1] (Llgl1) transcript in newly formed OL versus OPC, suggesting that Llgl[1] expression is increased upon OL differentiation
To directly test this notion, OPC were isolated from the white matter area of the corpus callosum (CC) of postnatal days 30–60 (P30–P60) mice and cultured in parallel under proliferation and differentiation conditions (Fig. 1a)

Summary

Introduction

Oligodendrocyte progenitor cells (OPC) undergo asymmetric cell division (ACD) to generate one OPC and one differentiating oligodendrocyte (OL) progeny. Time lapse and total internal reflection microscopy reveals a critical role for Lgl[1] in NG2 endocytic routing and links aberrant NG2 recycling to failed differentiation These data establish Lgl[1] as a suppressor of gliomagenesis and positive regulator of asymmetric division and differentiation in the healthy and demyelinated murine brain. ACD balances OPC proliferation with differentiation in the normal brain and generates OL in demyelinated lesions to contribute to remyelination[2,3,9,10] It is unclear how the downregulation of NG2 protein is achieved in the differentiating oligodendrocyte. OPC show higher rates of symmetric self-renewing divisions at the expense of ACD2 These data suggest that downregulation of NG2 in OPC progeny is critical for ACD, differentiation, and attenuation of tumorigenesis[2]. A tumor suppressive role for Lgl[1] in OPC has not been investigated yet

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