Meeting Abstract

P1.154  Saturday, Jan. 4 15:30  Appendage remodeling during metamorphosis and regeneration is characterized by a switch in Hedgehog signaling activity in the flour beetle, Tribolium castaneum DARAKANANDA, K*; VILLARREAL, C.M.; SUZUKI, Y; Wellesley College, Wellesley, MA; Wellesley College, Wellesley, MA; Wellesley College, Wellesley, MA kdarakan@wellesley.edu

One of the key innovations in insect evolution is holometaboly or complete metamorphosis. Insects that undergo complete metamorphosis typically undergo three morphologically distinct phases: the larval, the pupa, and the adult stages. In particular, appendage morphology changes during dramatically during metamorphosis. This transition is known to be mediated by a key hormone called juvenile hormone (JH). Yet, how the specific genetic and hormonal components regulate maintenance and regeneration of larval structures, and the transition from the larval to the adult morphology remains poorly understood. To identify signaling pathways that might interact with JH, an RNA-Seq screen was conducted. Hedgehog (Hh) pathway was identified as a candidate pathway that becomes activated during metamorphosis. Using the red flour beetle, Tribolium castaneum, the role of Hh and its antagonist, the receptor Patched (Ptc), were examined using RNA interference. Downregulation of Hh resulted in disrupted limb patterning during metamorphosis and inhibition of larval limb regeneration. In contrast, the absence of Ptc led to over-proliferation of cells and ectopic outgrowths in larval limbs. Thus, during larval phase, Hh signaling is actively suppressed by Ptc but becomes activated during metamorphosis, indicating a potential interaction between Hh signaling and JH. In addition, given that Sonic hedgehog is also necessary for vertebrate regeneration, our results suggest a possible conserved role for Hh signaling during regeneration across metazoans.