B-type nuclear lamin and the nuclear pore complex Nup107-160 influences maintenance of the spindle envelope required for cytokinesis inDrosophilamale meiosis

Abstract

In higher eukaryotes, nuclear envelope (NE) disassembly allows chromatin to condense and spindle microtubules to access kinetochores. The nuclear lamina, which strengthens the NE, is composed of a polymer meshwork made of A- and B-type lamins. We found that the B-type lamin (Lam) is not fully disassembled and continues to localize along the spindle envelope structure during Drosophila male meiosis I, while the A-type lamin (LamC) is completely dispersed throughout the cytoplasm. Among the nuclear pore complex proteins, Nup107 co-localized with Lam during this meiotic division. Surprisingly, Lam depletion resulted in a higher frequency of cytokinesis failure in male meiosis. We also observed the similar meiotic phenotype in Nup107-depleted cells. Abnormal localization of Lam was found in the Nup-depleted cells at premeiotic and meiotic stages. The central spindle microtubules became abnormal and recruitment of a contractile ring component to the cleavage sites was disrupted in Lam-depleted cells and Nup107-depleted cells. Therefore, we speculate that both proteins are required for a reinforcement of the spindle envelope, which supports the formation of central spindle microtubules essential for cytokinesis in Drosophila male meiosis.

Microtubule Assembly and Pole Coalescence: Early Steps in C. elegans Oocyte Meiosis I Spindle Assembly

“…Some or all of these defects could be indirectly due to disruptions in the nuclear import of factors required for a fully functional spindle to assemble, and we did detect variable and sometimes lower levels of some kinetochore proteins after LMN-1 knockdown (data not shown). Nevertheless, our results indicate that the nuclear lamina plays an important role in C. elegans oocyte meiotic spindle assembly, and roles for lamins in spindle assembly have also been reported in Xenopus extracts and during Drosophila male meiosis(Goodman et al, 2010; Hayashi et al, 2016; Tsai et al, 2006).…”

Genomic Instability Is Induced by Persistent Proliferation of Cells Undergoing Epithelial-to-Mesenchymal Transition

“…To further validate the contribution of compromised NE integrity to the mitotic phenotypes induced by TGFβ, we selected LaminB1, a major determinant of nuclear shape and size with a dual role in regulating cytokinesis, spindle matrix and chromatin condensation (Gruenbaum and Foisner, 2015; Guttinger et al, 2009; Hayashi et al, 2016; Martin et al, 2010; Tsai et al, 2006; Verstraeten et al, 2011), for more detailed analysis. TGFβ suppressed Lamins A and B1 proteins in MCF10A, SKBR3 as well as CDβgeo cells, whereas its removal restored the levels of Lamins (Fig.…”

“…Specifically, LaminB1, suppressed by TGFβ and SNAIL, plays an important role in cytokinesis, spindle assembly and chromatin condensation (Funkhouser et al, 2013; Hayashi et al, 2016; Martin et al, 2010; Tsai et al, 2006; Verstraeten et al, 2011). Disruption of LaminB1 causes cause nuclear blebbing (Funkhouser et al, 2013), and cytokinesis failure leading to BN and MN cells (Funkhouser et al, 2013; Hayashi et al, 2016; Martin et al, 2010; Tsai et al, 2006; Verstraeten et al, 2011), thus, phenocopying the effects of TGFβ. Accordingly, restoring LaminB1 partially rescues the mitotic abnormalities induced by TGFβ suggesting that additional NE components suppressed by TGFβ are also likely to contribute to the cytokinesis and mitotic defects observed in cells undergoing EMT.…”

Nuclear Export of Cyclin B Mediated by the Nup62 Complex Is Required for Meiotic Initiation in Drosophila Males

“…FG-Nups bind to proteins that shuttle between the nucleus and cytoplasm [10,11]. The FG-barrier constructed by the FG-Nups allows the selective transport of these proteins [12][13][14].As most of the Nups are well-conserved in Drosophila, we decided to investigate the role of the NPC in spermatogenesis using this model animal that allows well-advanced genetic analyses [15][16][17]. A previous study using spermatocyte-specific RNAi experiments investigated whether the depletion of the 30 Nups affected the progression of premeiotic cells through meiosis [17].…”

HiPLA: High-throughput imaging Proximity Ligation Assay

“…Since its original inception to detail the levels of platelet-derived growth factor in solution [28], the PLA has been optimized for in situ detection of the interaction between two proteins of interest using antibodies of different originating species [8,25]. This approach has been successfully utilized to probe a variety of cellular interactions including those of the lamin proteins with the polycomb complex [29], DNA damage foci [30], the E3 ubiquitin ligase Smurf2 [31,32], and the protein phosphatase 2A protein CIP2A [33], as well lamin interactions with other nuclear membraneassociated proteins [34,35]. Given the demonstrated utility of PLA in probing lamin function and the drastic changes observed in the organization of the nuclear lamina in the presence of the diseasecausing progerin protein, we sought to develop the PLA in a high-throughput format, referred to as HiPLA, and applied it as proof-of-principle to comprehensively probe the lamin interactome in a model of HGPS.…”