Vacuolar protein sorting 4 is required for silkworm metamorphosis

Area of Science:

• Cell Biology
• Developmental Biology
• Insect Science

Background:

• Vacuolar protein sorting 4 (Vps4) has known roles in the multivesicular body (MVB) pathway and other cellular processes.
• Its physiological functions at the organism level are not well understood.
• Homologues of Vps4 and its regulator Vta1 were identified in the silkworm, Bombyx mori.

Purpose of the Study:

• To characterize the transcriptional and protein expression profiles of BmVps4 and BmVta1 during silkworm development and in various tissues.
• To investigate the physiological roles of BmVps4 at the organism level in Bombyx mori.

Main Methods:

• Fluorescence quantitative real-time PCR to analyze gene transcription.
• Western blot to assess protein expression.
• RNA interference (RNAi) to knock down BmVps4 expression.

Main Results:

• BmVps4 and BmVta1 expression levels were significantly up-regulated during metamorphosis, adulthood, and embryogenesis compared to larval stages.
• BmVps4 transcription showed dynamic changes during the fifth instar, peaking during pupation and decreasing in adulthood.
• Knockdown of BmVps4 resulted in inhibited silk gland growth, shortened spinning duration, prolonged pupation, reduced pupal size and weight, and increased moth wing defects.

Conclusions:

• BmVps4 plays a critical and multifaceted role in silkworm metamorphosis.
• The study demonstrates essential organism-level functions of Vps4 in insect development beyond its known cellular roles.