Loss of MYO5B expression deregulates late endosome size which hinders mitotic spindle orientation

Abstract

MYO5B; Epithelial architecture; Recycling endosomes

MYO5B; Arquitectura epitelial; Reciclaje de endosomas

MYO5B; Arquitectura epitelial; Reciclatge d'endosomes

Recycling endosomes regulate plasma membrane recycling. Recently, recycling endosome–associated proteins have been implicated in the positioning and orientation of the mitotic spindle and cytokinesis. Loss of MYO5B, encoding the recycling endosome–associated myosin Vb, is associated with tumor development and tissue architecture defects in the gastrointestinal tract. Whether loss of MYO5B expression affects mitosis is not known. Here, we demonstrate that loss of MYO5B expression delayed cytokinesis, perturbed mitotic spindle orientation, led to the misorientation of the plane of cell division during the course of mitosis, and resulted in the delamination of epithelial cells. Remarkably, the effects on spindle orientation, but not cytokinesis, were a direct consequence of physical hindrance by giant late endosomes, which were formed in a chloride channel–sensitive manner concomitant with a redistribution of chloride channels from the cell periphery to late endosomes upon loss of MYO5B. Rab7 availability was identified as a limiting factor for the development of giant late endosomes. In accordance, increasing rab7 availability corrected mitotic spindle misorientation and cell delamination in cells lacking MYO5B expression. In conclusion, we identified a novel role for MYO5B in the regulation of late endosome size control and identify the inability to control late endosome size as an unexpected novel mechanism underlying defects in cell division orientation and epithelial architecture.

AD: Association for International Cancer Research (AICR13-0245), https://www.aicr.org AD: European Regional Development Fund (ERDF; PI16/00540 and AC15/00066), https://ec.europa.eu/regional_policy/en/funding/erdf AD: Spanish Association Against Cancer (AECC GCA15152966ARAN), https://www.uicc.org AD: the Instituto de Salud Carlos III, https://www.isciii.es/Paginas/Inicio.aspx IZ: The Dutch Research Council, Domain Applied and Engineering Sciences, https://www.nwo.nl/en JK: The Netherlands Organisation for Health Research and Development, 91111.006, https://www.zonmw.nl/en/ JK: The Dutch Research Council, 175-010-2009-023, https://www.nwo.nl/en CK: Chinese Scholarship Council, https://www.chinesescholarshipcouncil.com/ QL: Chinese Scholarship Council, https://www.chinesescholarshipcouncil.com/ YC: Chinese Scholarship Council, https://www.chinesescholarshipcouncil.com/