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Beachum, A. N.

Publications and source records attributed to Beachum, A. N..

2 recordsLinked to original sources

Glia multitask to compensate for neighboring glial cell dysfunction

As glia mature, they undergo glial tiling to abut one another without invading each others boundaries. Upon the loss of the secreted neurotrophin Spatzle3 (Spz3), Drosophila cortex glia transform morphologically and lose their intricate interactions with neurons and surrounding glial subtypes. Here, we reveal that all neighboring glial cell types (astrocytes, ensheathing glia, and subperineurial glia) react by extending processes into the previous cortex glial territory to compensate for lost cortex glial function and reduce the buildup of neuronal debris. However, the loss of Spz3 alone is not sufficient for glia to cross their natural borders, as blocking CNS growth via nutrient-restriction blocks the aberrant infiltration induced by the loss of Spz3. Surprisingly, even when these neighboring glia divert their cellular resources beyond their typical borders to take on new compensatory roles, they are able to multitask to continue to preserve their own normal functions to maintain CNS homeostasis. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=136 SRC="FIGDIR/small/611719v1_ufig1.gif" ALT="Figure 1"> View larger version (53K): org.highwire.dtl.DTLVardef@1a1a884org.highwire.dtl.DTLVardef@3ea222org.highwire.dtl.DTLVardef@676b7org.highwire.dtl.DTLVardef@5c21d6_HPS_FORMAT_FIGEXP M_FIG C_FIG

neuroscience↗

β-importins Tnpo-SR and Cadmus and the small GTPase Ran promote ovarian cyst formation in Drosophila

Germ cells undergo mitotic expansion via incomplete cytokinesis, forming cysts of undifferentiated cells that remain interconnected prior to meiotic initiation, through mechanisms that are not well-defined. In somatic cells, Ras-related nuclear protein (Ran) spatiotemporally regulates mitotic spindle assembly, cleavage furrow formation and abscission. Here, we identify Ran and {beta}-importins as critical regulators of cyst development in the Drosophila ovary. Depletion of Ran or the {beta}-importins Tnpo-SR and cadmus disrupts oocyte selection and results in egg chambers with variable numbers of germ cells, suggesting abnormal cyst development and cyst fragmentation. We demonstrate that Ran, Tnpo-SR, and Cadmus regulate key cellular processes during cyst formation, including cell cycle dynamics, fusome biogenesis, and ring canal stability, yet do so independently of mitotic spindle assembly. Further, Tnpo-SR and Cadmus control cyclin accumulation and suppress cytokinesis independent of Ran-GTP, suggesting that {beta}-importins sequester protein cargos that normally promote the mitotic-to-meiotic transition. Our data demonstrates that Ran and {beta}-importins are critical for germ cell cyst formation, a role that is likely conserved in other organisms. SUMMARY STATEMENTRan and two {beta}-importins function coordinately to promote oocyte selection and cyst development in the Drosophila ovary.

developmental biology↗