Tisheng Shan, Yang Wang, Neal T Dittmer, Michael R Kanost, Haobo Jiang
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引用次数: 2
Abstract
The melanization and Toll pathways, regulated by a network of serine proteases and noncatalytic serine protease homologs (SPHs), have been investigated mostly in adult and larval insects. However, how these innate immune reactions are regulated in insect eggs remains unclear. Here we present evidence from transcriptome and proteome analyses that extra-embryonic tissues (yolk and serosa) of early-stage Manduca sexta eggs are immune competent, with expression of immune effector genes including prophenoloxidase and antimicrobial peptides. We identified gene products of the melanization and Toll pathways in M. sexta eggs. Through in vitro reconstitution experiments, we demonstrated that constitutive and infection-induced serine protease cascade modules that stimulate immune responses exist in the extra-embryonic tissues of M. sexta eggs. The constitutive module (HP14b-SP144-GP6) may promote rapid early immune signaling by forming a cascade activating the cytokine Spätzle and regulating melanization by activating prophenoloxidase (proPO). The inducible module (HP14a-HP21-HP5) may trigger enhanced activation of Spätzle and proPO at a later phase of infection. Crosstalk between the two modules may occur in transition from the constitutive to the induced response in eggs inoculated with bacteria. Examination of data from two other well-studied insect species, Tribolium castaneum and Drosophila melanogaster, supports a role for a serosa-dependent constitutive protease cascade in protecting early embryos against invading pathogens.
期刊介绍:
The ''Journal of Innate Immunity'' is a bimonthly journal covering all aspects within the area of innate immunity, including evolution of the immune system, molecular biology of cells involved in innate immunity, pattern recognition and signals of ‘danger’, microbial corruption, host response and inflammation, mucosal immunity, complement and coagulation, sepsis and septic shock, molecular genomics, and development of immunotherapies. The journal publishes original research articles, short communications, reviews, commentaries and letters to the editors. In addition to regular papers, some issues feature a special section with a thematic focus.