Drosophila Wash and the Wash regulatory complex function in nuclear envelope budding

Abstract

Nuclear envelope budding is a recently described phenomenon wherein large macromolecular complexes are packaged inside the nucleus and extruded through the nuclear membranes. While a general outline of the cellular events occurring during NE-budding is now in place, little is yet known about the molecular machinery and mechanisms underlying the physical aspects of NE-bud formation. Using a multidisciplinary approach, we identify Wash, its regulatory complex (SHRC), capping protein, and Arp2/3 as new molecular components involved in the physical aspects of NE-bud formation. Interestingly, Wash affects NE-budding in two ways: indirectly through general nuclear lamina disruption via an SHRC-independent interaction with Lamin B leading to inefficient NE-bud formation, and directly blocking NE-bud formation along with its SHRC, capping protein, and Arp2/3. In addition to NE-budding emerging as an important cellular process, it shares many similarities with herpesvirus nuclear egress mechanisms suggesting new avenues for exploration in both normal and disease biology.

Nuclear envelope budding is a response to cellular stress

“…However, herpes simplex virus replicates in the nucleoplasm and is released into the cytosol via an outwards budding of the nuclear envelope (10)(11)(12)(13). This demonstrates another pathway for nuclear export and there have been several observations suggesting that nuclear envelope budding (NEB) also occurs in healthy cells, with different interpretations of this mechanism being suggested (14)(15)(16)(17)(18)(19)(20)(21)(22)(23)(24)(25)(26)(27). These observations were made in a diverse set of organisms but primarily using cells that are under differentiation (embryonic cells) and various terminologies were given to describe the NEB process (Supplementary Table 1).…”

Drosophila Keap1 oxidative/xenobiotic response factor interacts with B-type lamin to regulate nuclear lamina and heterochromatin

“…Several other mis-localized lamin phenotypes have been reported. In Drosophila , reduction of a WAS family protein wash in salivary gland cells results in reduced nuclear envelope budding and patternless strands of Lamin throughout the nucleoplasm (Verboon et al , 2020). Overexpression of an inner nuclear membrane protein Kugelkern in Drosophila embryos and mouse fibroblasts results in infoldings of the nuclear membrane and “blebs” of the nuclear envelope, respectively (Polychronidou et al , 2010).…”

Deliver on Time or Pay the Fine: Scheduling in Membrane Trafficking

“…Retromer subunits recognize two distinct signals localizing at t endosome membrane surface: phosphatidylinositol-3-phosphate (PtdIns(3)P), a phosph inositide-derived lipid, and hydrophobic signal peptides encoded on the cytoplasmic ta of transmembrane protein cargoes (e.g., sorting motifs or bipartite sorting motifs) [66,6 The dimeric subunit binds the endosomal-enriched lipid PtdIns(3)P, whereas sorting m tifs such as e NPXY or YXXØ are recognized by the Vps35p, Vps29p Vps26p trimeric com plex [68]. Once recruited and assembled, the Retromer complex guides creation of fi mentous actin (F-actin)-enriched domains, through association with the Wiskott-Aldri syndrome and SCAR homologue (WASH) complex [69,70]. At the molecular level, t WASH complex is composed of WASH1, FAM21, SWIP (Strumpellin and WASH-int acting protein), Strumpellin, and CCDC53 (coiled coil domain containing protein 53) [7 FAM21 binds to Vps35, the Retromer subunit, thereby connecting the actin machinery In parallel, ESCRT complexes recognize and direct ubiquitylated protein towards the lysosome for degradation.…”

“…The dimeric subunit binds the endosomal-enriched lipid PtdIns(3)P, whereas sorting motifs such as e NPXY or YXXØ are recognized by the Vps35p, Vps29p Vps26p trimeric complex [68]. Once recruited and assembled, the Retromer complex guides creation of filamentous actin (F-actin)-enriched domains, through association with the Wiskott-Aldrich syndrome and SCAR homologue (WASH) complex [69,70]. At the molecular level, the WASH complex is composed of WASH1, FAM21, SWIP (Strumpellin and WASH-interacting protein), Strumpellin, and CCDC53 (coiled coil domain containing protein 53) [71].…”