RT Journal Article
SR Electronic
T1 An ancestral apical brain region contributes to the central complex under the control of <em>foxQ2</em> in the beetle <em>Tribolium castaneum</em>
JF bioRxiv
FD Cold Spring Harbor Laboratory
SP 661199
DO 10.1101/661199
A1 Bicheng He
A1 Marita Buescher
A1 Max Stephen Farnworth
A1 Frederic Strobl
A1 Ernst Stelzer
A1 Nikolaus Dieter Bernhard Koniszewski
A1 Dominik Mühlen
A1 Gregor Bucher
YR 2019
UL http://biorxiv.org/content/early/2019/06/06/661199.abstract
AB The genetic control of anterior brain development is highly conserved throughout animals. For instance, a conserved anterior gene regulatory network specifies the ancestral neuroendocrine center of animals and the apical organ of marine organisms. However, its contribution to the brain in non-marine animals has remained elusive. Here, we study the function of the Tc-foxQ2 forkhead transcription factor, a key regulator of the anterior gene regulatory network of insects. We characterized four distinct types of Tc-foxQ2 positive neural progenitor cells based on differential co-expression with Tc-six3/optix, Tc-six4, Tc-chx/vsx, Tc-nkx2.1/scro, Tc-ey, Tc-rx and Tc-fez1. An enhancer trap line built by genome editing marked Tc-foxQ2 positive neurons, which projected through the primary brain commissure and later through a subset of commissural fascicles. Eventually, they contributed to the central complex. Strikingly, in Tc-foxQ2 RNAi knock-down embryos the primary brain commissure did not split and subsequent development of midline brain structures stalled. Our work establishes foxQ2 as a key regulator of brain midline structures, which distinguish the protocerebrum from segmental ganglia. Unexpectedly, our data suggest that the central complex evolved by integrating neural cells from an ancestral anterior neuroendocrine center.Summary statement An ancestral neuroendocrine center contributes to the evolution of the central complex. foxQ2 is a gene required for the development of midline structures of the insect brain, which distinguish protocerebrum from segmental ganglia.