Meru couples planar cell polarity with apical-basal polarity during asymmetric cell division

Abstract

Polarity is a shared feature of most cells. In epithelia, apical-basal polarity often coexists, and sometimes intersects with planar cell polarity (PCP), which orients cells in the epithelial plane. From a limited set of core building blocks (e.g. the Par complexes for apical-basal polarity and the Frizzled/Dishevelled complex for PCP), a diverse array of polarized cells and tissues are generated. This suggests the existence of little-studied tissue-specific factors that rewire the core polarity modules to the appropriate conformation. In Drosophila sensory organ precursors (SOPs), the core PCP components initiate the planar polarization of apical-basal determinants, ensuring asymmetric division into daughter cells of different fates. We show that Meru, a RASSF9/RASSF10 homologue, is expressed specifically in SOPs, recruited to the posterior cortex by Frizzled/Dishevelled, and in turn polarizes the apical-basal polarity factor Bazooka (Par3). Thus, Meru belongs to a class of proteins that act cell/tissue-specifically to remodel the core polarity machinery.DOI: http://dx.doi.org/10.7554/eLife.25014.001

An RNAi Screen Identifies New Genes Required for Normal Morphogenesis of Larval Chordotonal Organs

“…The meru gene was identified by Reeves and Posakony ( Reeves and Posakony 2005 ) as a direct target of the proneural genes and was implicated in the sensory perception of pain by ( Neely et al 2010 ). More recently, ( Banerjee et al 2017 ) have identified Meru as a modulator of cell polarity that connects planar cell polarity with apical-basal polarity during asymmetric cell divisions within the external sensory organ lineage. The identification of meru in the current screen points to a possible role of meru in the ChO lineage as well.…”

Regulated Activation of the PAR Polarity Network Ensures a Timely and Specific Response to Spatial Cues

“…Temporal shifts in the behavior of polarity networks are widespread in developmental systems, as polarity components are rewired and repurposed in different cell types or through the cell cycle (e.g [49, 50, 51]). Mitotic entry directly regulates polarity network activity in many common models, including Drosophila neuroblasts [31, 32, 48] and S. cerevisiae [52, 53].…”

Par3 interacts with Prickle3 to generate apical PCP complexes in the vertebrate neural plate

“…Whereas the mechanism responsible for this planar polarization is not known, the same biochemical or mechanical signals that affect core PCP proteins ( Chien et al, 2015 ; Chu and Sokol, 2016 ) ( Kim et al, 2018 ) are likely to regulate Par3. One possibility is that the association of core PCP protein complexes with Par3 may directly contribute to Par3 enrichment at specific locations ( Banerjee et al, 2017 ; Besson et al, 2015 ). In contrast to Xenopus Par3, fly Bazooka/Par3 is enriched at dorsoventral but not anteroposterior boundaries of intercalating cells during germ-band extension along the anteroposterior axis ( Simões et al, 2010 ).…”

“…Bazooka/Par3 and its associated proteins have been functionally linked to PCP in specific Drosophila tissues ( Beati et al, 2018 ; Blankenship et al, 2006 ; Djiane et al, 2005 ; Harris and Peifer, 2007 ; Simões et al, 2010 ; Wasserscheid et al, 2007 ; Zallen and Wieschaus, 2004 ). Additionally, the effects of core PCP components on Par3 localization have been demonstrated in fly photoreceptor cells and sensor organ progenitors ( Aigouy and Le Bivic, 2016 ; Banerjee et al, 2017 ; Bellaïche et al, 2004 ; Besson et al, 2015 ). In vertebrates, a recent study also suggested a link between Par3 and PCP ( Lin and Yue, 2018 ), but whether Par3 itself is planar polarized, and how it modulates the activity of core PCP proteins has not been investigated.…”