Genome-wide investigation and functional analysis of 20S proteasome subunits in Locusta migratoria

The 20S proteasome is a core component of the ubiquitin-proteasome system, participating in various biological processes such as cell cycle regulation, signal transduction, apoptosis, and protein homeostasis. However, its roles in mammals are well-documented, its function in the insect intestine remains largely unexplored. In this study, we identified 14 20S proteasome subunits, including 7 α-subunits and 7 β-subunits in Locusta migratoria, a worldwide agricultural pest. Phylogenetic tree revealed conservation of amino acid sequences among different species. While the conserved domains and motifs analysis exhibited both conservation and divergence among 20S proteasome subunits. The expression pattern of 20S proteasome subunits found that these subunits were expressed in all growth phases. Notably, a large number of 20S proteasome subunits were found to be expressed in ovary and midgut tissues. We further demonstrated that, except for increased expression of proteasome α7 and β5, other proteasome subunits were significantly reduced under 3 % dextran sulphate sodium condition. Additionally, the expression of 8 of 14 proteasome subunits were down-regulated after malathion treatment. However, the expression of most proteasome β subunits decreased significantly after deltamethrin treatment. RNAi targeting 20S proteasome subunits resulted in complete mortality in fifth-instar nymphs, midgut and gastric cecum atrophy, and significant reductions in body length and weight. Moreover, silencing of 20S proteasome subunits impaired ovarian growth. Furthermore, 20S proteasome subunits are also potential target genes for RNAi-based pest control strategies.