The Interplanar Amida Network (IPAN)
comprises microtubule vertical projections interlinked by lateral
filopodia-like structures. Credit: The EMBO Journal (2024). DOI: 10.1038/s44318-023-00025-w
Animal
development requires successive changes in cell and tissue structures. To form
complex 3D organs, cell shapes must adapt to support tissue morphogenesis.
However, our understanding of how cellular structure changes are coupled with
dynamic tissue morphogenesis is limited, largely due to reliance on studies of
fixed tissues and cultured cells. Real-time observation of cell shape changes
during morphogenesis is therefore crucial.
Researchers from the University of
Tartu, Estonia, and the University of Helsinki, Finland, have introduced a 5D
in vivo live-imaging protocol to observe 3D tissue dynamics with high
resolution. They discovered that dorsal and ventral cells in the fruit fly
Drosophila melanogaster's pupal wing form a cellular network, the Interplanar Amida Network (IPAN), through basal
microtubule (MT) protrusions.
This network sustains cellular
connections during early inflation stages and supports 3D tissue growth by
allowing MTs to reorganize into mitotic spindles following programmed
disassembly of cell-cell contacts. The findings are published in The
EMBO Journal.
A representative cluster of cells with
microtubule (MT) protrusions comprises the early interplanar amida network
(IPAN). The inset on the left provides an apical view of a subset of the cells
shown in a lateral view on the right. Cells with MT protrusions are connected
to each other via lateral actin-based filopodia and undergo bundling as some of
their MTs disassemble.The MT subunits generated from disassembly of protrusion
MTs are thought to contribute to the formation of the mitotic spindle within the
dividing cell. Credit: The animation was created by Erich Brutus.
This study not only reveals the physiological significance of the IPAN but also provides insights into the challenges of live-imaging and genetic manipulation of protrusions. The findings suggest that the loss of cell-cell contacts functions as a key regulator of coordinated mitoses, a mechanism that may be applicable to 3D morphogenesis in multicellular organisms. The use of powerful Drosophila genetics tools in combination with multi-colored fluorescent in vivo live-imaging offers a comprehensive system to address questions about cell shape changes impacting tissue morphogenesis.
by Estonian Research Council
Source: Live imaging reveals key cell dynamics in 3D organ formation in Drosophila (phys.org)
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