Relationship between Rab and insulin-like proteins in the nervous system of Bombyx mori

Tomohide Uno,Yusuke Ozakiya,Yuichi Uno,Kengo Kanamaru,Mako Sasao,Yasuo Yamauchi,Katsuhiko Sakamoto,Akira Mizoguchi

doi:10.14411/eje.2021.031

Abstract

Rab proteins are small GTP-binding proteins and are the largest family in the Ras GTPase superfamily and mediate vesicular transport in cells. Diverse insulin-like peptides, such as bombyxin, are synthesized in the brain and secreted into the haemolymph by the corpus allatum (CA). In the brain of Bombyx mori, Rabs are expressed in a specific area; however, which Rabs actually link the secretion of bombyxin remains unknown. A double-staining analysis of nine Rabs (Rab1, 3, 6, 7, 14, 21, 26, 39 and X4) and bombyxin indicated that Rab3-, Rab7-, Rab39- and RabX4-immunohistochemical reactivity (ir) areas overlapped with bombyxin-ir in the brain and CA in B. mori, while Rab6-, Rab14- and Rab21-irs partially overlapped in the CA. Rab1-ir occurred in the other immunopositive areas in CA. Rab26-ir did not occur in the brain. Rab39-ir occurred in UNC104, Rab39- effector, -immunopositive neurons in the brain and CA. Thus, Rab3, 7, 39 and X4 may regulate the exocytosis of bombyxin.

Highlights

Rab proteins belong to a large family of small GTPases that direct intracellular vesicular trafficking (Barr, 2013; Li & Marlin, 2015; Pfeffer, 2017)
Atnti-Rab39 and anti-Rab3 detected a restricted area in a set of neurons in the pars intercerebralis (PI), (Fig. 2d and 3j)
Rab proteins are master mediators of vesicular membrane trafficking of endocytic and exocytic pathways, primarily recruiting proteins and lipids required for vesicle formation, docking and fusion (Pereira-Leal & Seabra, 2001; Schwartz et al, 2007; Stenmark, 2009)

Summary

Introduction

Rab proteins belong to a large family of small GTPases that direct intracellular vesicular trafficking (Barr, 2013; Li & Marlin, 2015; Pfeffer, 2017). About 70 Rab GTPases are encoded in the human genome, up to 31 in Drosophila melanogaster and 11 in yeast (Brighouse et al, 2010). Active GTP-bound Rab proteins, recruit their cognate Rab effectors to the membrane surfaces, and, thereby, cooperate with the effectors to mediate diverse processes in intracellular membrane trafficking, including vesicle formation, vesicular transport, membrane tethering and fusion to target compartments (Pfeffer, 2013). UNC104 interacted with Rab and is a kinesin-related protein (ATPase, the Drosophila ortholog of the kinesin-3 KIF1A), which is a motor protein (Gillingham et al, 2014). Rab proteins participate in important cellular processes, such as the immune response, autophagy, neurotransmitter release, phagocytosis, development, fertility and oogenesis (Lighthouse et al, 2008; Uytterhoeven et al, 2011; Ye et al, 2012; Garg & Wu, 2014; Fujita et al, 2017; Elmogy et al, 2018; Caviglia et al, 2019)

Methods

Results

Conclusion