Nakamura Taro, Mito Taro, Miyawaki Katsuyuki, Ohuchi Hideyo, Noji Sumihare
Department of Life Systems, Institute of Technology and Science, The University of Tokushima, 2-1 Minami-Jyosanjima-cho, Tokushima 770-8506, Japan.
Dev Biol. 2008 Jul 1;319(1):46-55. doi: 10.1016/j.ydbio.2008.04.002. Epub 2008 Apr 15.
Nymphs of hemimetabolous insects, such as cockroaches and crickets, possess functional legs with a remarkable capacity for epimorphic regeneration. In this study, we have focused on the role of epidermal growth factor receptor (EGFR) signaling in regeneration of a nymphal leg in the cricket Gryllus bimaculatus. We performed loss-of-function analyses with a Gryllus Egfr homolog (Gb'Egfr) and nymphal RNA interference (RNAi). After injection of double-stranded RNA for Gb'Egfr in the body cavity of the third instar cricket nymph, amputation of the leg at the distal tibia resulted in defects of normal distal regeneration. The regenerated leg lacked the distal tarsus and pretarsus. This result indicates that EGFR signaling is required for distal leg patterning in regeneration during the nymphal stage of the cricket. Furthermore, we demonstrated that EGFR signaling acts downstream of the canonical Wnt/Wg signaling and regulates appendage proximodistal (PD) patterning genes aristaless and dachshund during regeneration. Our results suggest that EGFR signaling influences positional information along the PD axis in distal leg patterning of insects, regardless of the leg formation mode.
半变态昆虫的若虫，如蟑螂和蟋蟀，拥有功能健全的腿，具有显著的残肢再生能力。在本研究中，我们聚焦于表皮生长因子受体（EGFR）信号通路在双斑蟋若虫腿部再生中的作用。我们利用双斑蟋EGFR同源基因（Gb'Egfr）和若虫RNA干扰（RNAi）进行了功能丧失分析。在向三龄若虫的体腔注射针对Gb'Egfr的双链RNA后，在胫节远端截肢会导致正常远端再生出现缺陷。再生的腿缺少远端跗节和前跗节。这一结果表明，EGFR信号通路是蟋蟀若虫阶段腿部再生过程中远端腿部模式形成所必需的。此外，我们证明了EGFR信号通路在经典Wnt/Wg信号通路的下游起作用，并在再生过程中调节附肢近远轴（PD）模式形成基因无触角和腊肠基因。我们的结果表明，EGFR信号通路影响昆虫远端腿部模式形成中沿PD轴的位置信息，而与腿部形成模式无关。
