Cdc42 regulates cell polarization and contractile actomyosin rings during terminal differentiation of human erythroblasts

Kumi Ubukawa,Tatsufumi Goto,Yumi Sasaki,Ken Asanuma,Kenichi Sawada,Isuzu Kobayashi,Hideki Wakui,Yong-Mei Guo,Naoto Takahashi

doi:10.1038/s41598-020-68799-1

Kumi Ubukawa, Tatsufumi Goto + Show 7 more

Open Access

https://doi.org/10.1038/s41598-020-68799-1

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Abstract

The molecular mechanisms involved in the terminal differentiation of erythroblasts have been elucidated by comparing enucleation and cell division. Although various similarities and differences between erythroblast enucleation and cytokinesis have been reported, the mechanisms that control enucleation remain unclear. We previously reported that dynein and microtubule-organizing centers mediated the polarization of nuclei in human erythroblasts. Moreover, the accumulation of F-actin was noted during the enucleation of erythroblasts. Therefore, during enucleation, upstream effectors in the signal transduction pathway regulating dynein or actin, such as cell division control protein 42 homolog (Cdc42), may be crucial. We herein investigated the effects of the Cdc42 inhibitor, CASIN, on cytokinesis and enucleation in colony-forming units-erythroid (CFU-Es) and mature erythroblasts (day 10). CASIN blocked the proliferation of CFU-Es and their enucleation in a dose-dependent manner. Dynein adopted an island-like distribution in the cytoplasm of non-treated CFU-Es, but was concentrated near the nucleus as a dot and co-localized with γ-tubulin in CASIN-treated cells. CASIN blocked the accumulation of F-actin in CFU-Es and day 10 cells. These results demonstrated that Cdc42 plays an important role in cytokinesis, nuclear polarization and nuclear extrusion through a relationship with dynein and actin filament organization during the terminal differentiation of erythroblasts.

Highlights

The molecular mechanisms involved in the terminal differentiation of erythroblasts have been elucidated by comparing enucleation and cell division
Ji et al showed that mammalian diaphanous-related formin (mDia)[2] plays a significant role in enucleation by affecting the formation of the contractile actomyosin ring in mouse e rythroblasts[7]. These findings indicate that Cdc[42] regulates the enucleation of human erythroblasts mediated by mDia[2]
The expression of CD71 decreased in DMSO-treated cells, but not in CASIN-treated cells, which was similar to the expression of CD71 in cells at 0 h (Fig. 2E). These results showed that the inhibition of Cdc[42] by CASIN blocked the proliferation and differentiation of CFU-Es

Summary

Introduction

The molecular mechanisms involved in the terminal differentiation of erythroblasts have been elucidated by comparing enucleation and cell division. CASIN blocked the accumulation of F-actin in CFU-Es and day 10 cells These results demonstrated that Cdc[42] plays an important role in cytokinesis, nuclear polarization and nuclear extrusion through a relationship with dynein and actin filament organization during the terminal differentiation of erythroblasts. A number of crucial signal transduction effectors, including phosphatidylinositol-3-kinase (PI3K)[6], have been shown to play a role in the enucleation process, mainly through phosphorylation events These findings strongly support a signal transduction system governing cell polarity, dynein accumulation, and the reorganization of actin filaments through mammalian diaphanous-related formin (mDia) 2, the signal transduction pathway involved has not yet been identified[1,7]. F-actin and non-muscle myosin IIB are involved in the enucleation of erythroblasts, enucleation and cytokinesis are not the same phenomenon

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