Function Of The Cathepsin D In Tissue Remodeling Of The Cotton Bollworm,Helicoverpa Armigera

Backgrounds and research progressInsect development is a highly coordinated process regulated by hormones,which regulates the expression of specific proteins.The expressed proteins then function to complete the development of insects.Holometabolous insects undergo egg,larva,pupa and adult stage during their life cycle.In the process of larvae to pupae,insects undergo programmed cell death(PCD),the larva tissue degradate.During the PCD process,a variety of proteases was shown to be involved in it,cathepsin B,cathepsin L,cathepsin F and cathepsin D.According to the active sites diversity,cathepsins are categorized into cysteine cathepsins(B,C,H,F,K,L,O,S,V,W),aspartic acid cathepsins(D,E)and serine cathepsins(A,G).Our research focused on function of cathepsin D in midgut during PCD,to provide target genes for pest control.Scientific questionWhile researches have shown that during larval midgut PCD,mRNA expression of CathD was increased,but little was known about its change of proenzyme form to mature form.Its localization during midgut reconstruction process isn't clear too.Its function in PCD still needs investigation.Research results1.CathD expression has tissue specificity;it was detected in midgut and integument,but not in fat body.And its mature form was found in midgut,proenzyme was found in integument.2.CathD was localized in larval midgut which undergoes PCD.3.Knockdown of CathD by RNAi delayed larval pupation and blocked larval midgut PCDInnovation and importance of this researchWe first discovered that CathD has tissue specific distruction,the mature form was found in midgut but the proenzyme form was found in integument.The mature form in midgut plays a role in larval midgut PCD,while the function of proenzyme in integument needs further investigation.