Neuropeptide Bursicon: Signaling Pathways from Cuticle Tanning, Stem Cell Proliferation to Immune Regulation
Shiheng An1, Shengzhang Dong2, Hongwei Zhang3 and Qisheng Song*3
1. Department of Entomology, Henan Agricultural University, Zhengzhou, Henan, China
2. Department of Molecular Microbiology and Immunology, Johns Hopkins University, Baltimore, MD 21218, USA
3. Molecular Insect Physiology Laboratory，Division of Plant Sciences, University of Missouri, Columbia, MO 65211, USA
Bursicon is a neuropeptide hormone consisting of two cystine-knot proteins (burs α and burs β) and could form heterodimer and homodimer to regulate different biological functions. Bursicon heterodimer acts via a specific Drosophila leucine-rich G protein-coupled receptor 2 to mediate the tanning (hardening and darkening) of newly formed cuticle after each molt. However, bursicon homodimer’s function remained unclear until very recently. We found that bursicon homodimer regulates the expression of antimicrobial peptides in Drosophila melanogaster and Aedes aegypti via the IMD pathway by activating transcription factor NFkB. It also activated the JAK/STAT pathway via STAT92E phosphorylation. Interestingly, bursicon α homodimer was also expressed in the posterior midgut cells. RNAi knockdown of burs α in midgut cells led to significant increase in midgut length, suggesting the expression of burs α in midgut is necessary to maintain midgut homeostasis. The roles of key components in the IMD and JAK/STAT pathways as well as stem cell proliferation regulated by bursicon homodimers will be discussed.
Key Words: Bursicon homodimer, neuropeptide, antimicrobial peptide, IMD, JAK/STAT, NFkB, STAT92E, phosphorylation, signal transduction
Shiheng An1, Shengzhang Dong2, Hongwei Zhang3 and Qisheng Song*3
1. Department of Entomology, Henan Agricultural University, Zhengzhou, Henan, China
2. Department of Molecular Microbiology and Immunology, Johns Hopkins University, Baltimore, MD 21218, USA
3. Molecular Insect Physiology Laboratory，Division of Plant Sciences, University of Missouri, Columbia, MO 65211, USA
Bursicon is a neuropeptide hormone consisting of two cystine-knot proteins (burs α and burs β) and could form heterodimer and homodimer to regulate different biological functions. Bursicon heterodimer acts via a specific Drosophila leucine-rich G protein-coupled receptor 2 to mediate the tanning (hardening and darkening) of newly formed cuticle after each molt. However, bursicon homodimer’s function remained unclear until very recently. We found that bursicon homodimer regulates the expression of antimicrobial peptides in Drosophila melanogaster and Aedes aegypti via the IMD pathway by activating transcription factor NFkB. It also activated the JAK/STAT pathway via STAT92E phosphorylation. Interestingly, bursicon α homodimer was also expressed in the posterior midgut cells. RNAi knockdown of burs α in midgut cells led to significant increase in midgut length, suggesting the expression of burs α in midgut is necessary to maintain midgut homeostasis. The roles of key components in the IMD and JAK/STAT pathways as well as stem cell proliferation regulated by bursicon homodimers will be discussed.
Key Words: Bursicon homodimer, neuropeptide, antimicrobial peptide, IMD, JAK/STAT, NFkB, STAT92E, phosphorylation, signal transduction