Journal Article

PTEN controls glandular morphogenesis through a juxtamembrane β-Arrestin1/ARHGAP21 scaffolding complex

Javadi, Arman, Blondel-Tepaz, Elodie, Deevi, Ravi K, Baillie, George S, Scott, Mark GH, Campbell, Frederick C, Evergren, Emma

2017

Overview

PTEN controls three-dimensional (3D) glandular morphogenesis by coupling juxtamembrane signaling to mitotic spindle machinery. While molecular mechanisms remain unclear, PTEN interacts through its C2 membrane-binding domain with the scaffold protein β-Arrestin1. Because β-Arrestin1 binds and suppresses the Cdc42 GTPase-activating protein ARHGAP21, we hypothesize that PTEN controls Cdc42 -dependent morphogenic processes through a β-Arrestin1-ARHGAP21 complex. Here, we show that PTEN knockdown (KD) impairs β-Arrestin1 membrane localization, β-Arrestin1-ARHGAP21 interactions, Cdc42 activation, mitotic spindle orientation and 3D glandular morphogenesis. Effects of PTEN deficiency were phenocopied by β-Arrestin1 KD or inhibition of β-Arrestin1-ARHGAP21 interactions. Conversely, silencing of ARHGAP21 enhanced Cdc42 activation and rescued aberrant morphogenic processes of PTEN-deficient cultures. Expression of the PTEN C2 domain mimicked effects of full-length PTEN but a membrane-binding defective mutant of the C2 domain abrogated these properties. Our results show that PTEN controls multicellular assembly through a membrane-associated regulatory protein complex composed of β-Arrestin1, ARHGAP21 and Cdc42. The protein PTEN helps to organize cells in the body to form complex structures. In particular, it collects signals from a cells’ surroundings and changes where cells divide so new cells are produced in the right places. The control of cell division by PTEN is also thought to help limit the progression and spread of cancer. PTEN can interact with another protein called β-Arrestin1, which behaves as a so-called scaffolding protein – in other words, one that helps groups of proteins to interact with each other. β-Arrestin1 has been found to control cell division via a series of other proteins, including ARHGAP21 and Cdc42. The relationship between PTEN and these other proteins in dividing cells is still not fully understood. Javadi, Deevi et al. studied PTEN in human cells grown in the laboratory to show that a part of PTEN known as the C2 domain allows it to help organize cells by moving β-Arrestin1 to the outer edge of the cell – the cell membrane. This relocation allows β-Arrestin1 to interact with ARHGAP21 and Cdc42, and control cell division. Active Cdc42 changes the orientation of cell division, allowing cells to organize into single layers of regular cells and similar tightly controlled structures. Further experiments revealed that these proteins are important to form tubes inside the glands of the gut. The C2 region of PTEN also helps to detect signals carried by fat molecules in the cell membrane, so these results provide a direct link between signaling and cell organization via PTEN. The work of Javadi, Deevi et al. provides new understanding of how PTEN links nutrient availability to cell organization during development and may also lead to new insights into the role of PTEN in limiting the growth of tumors.

• Publisher: eLife Sciences Publications Ltd,eLife Sciences Publications, Ltd
• Subject: Animals / ARHGAP21 / Arrestin / beta-Arrestin 1 - antagonists & inhibitors / beta-Arrestin 1 - genetics / beta-Arrestin 1 - metabolism / Binding Sites / Caco-2 Cells / Cancer / Cancer Biology / cdc42 GTP-Binding Protein - genetics / cdc42 GTP-Binding Protein - metabolism / Cdc42 protein / Cell Biology / Cell division / Cell Membrane - metabolism / Cell Membrane - ultrastructure / Defective mutant / Gene Expression Regulation / GTPase-activating protein / GTPase-Activating Proteins - antagonists & inhibitors / GTPase-Activating Proteins - genetics / GTPase-Activating Proteins - metabolism / Guanosine triphosphatases / HCT116 Cells / HEK293 Cells / Humans / Immunoglobulins / Kinases / Localization / Membrane proteins / Mice / Mice, Inbred C57BL / Microscopy / Molecular modelling / Morphogenesis / Organoids - cytology / Organoids - metabolism / Organoids - ultrastructure / Phosphatase / Protein Binding / Proteins / PTEN / PTEN Phosphohydrolase - antagonists & inhibitors / PTEN Phosphohydrolase - genetics / PTEN Phosphohydrolase - metabolism / PTEN protein / RNA, Small Interfering - genetics / RNA, Small Interfering - metabolism / Signal Transduction / Software / Spindle Apparatus - metabolism / Spindle Apparatus - ultrastructure / Tissue Culture Techniques