Retrotransposon 3S18 forms self-protective aggregates and prolongs mid-oogenesis

Area of Science:

• Genetics
• Developmental Biology
• Molecular Biology

Background:

• Transposons are mobile genetic elements found in most genomes.
• Transposon products can impact host cells even before genomic integration.
• Oogenesis is a critical developmental process susceptible to cellular disruptions.

Purpose of the Study:

• To investigate the impact of transposon activation on Drosophila oogenesis.
• To identify specific transposons and their mechanisms affecting host development.
• To understand how transposon products influence cellular processes and propagation.

Main Methods:

• Analysis of transposon-induced phenotypes in Drosophila oocytes.
• Identification and characterization of specific long terminal repeat (LTR) retrotransposons.
• Microscopy and live imaging to observe ribonucleoprotein (RNP) aggregate formation and dynamics.
• Genetic screening to identify suppressors of RNP aggregate formation.

Main Results:

• Transposon activation leads to smaller mid-stage oocytes and prolonged mid-oogenesis in Drosophila.
• The LTR retrotransposon 3S18 is a primary contributor to these observed phenotypes.
• 3S18 mRNA and integrase form large RNP aggregates at cell-cell bridges.
• Suppression of 3S18 RNP aggregates reduces 3S18 mRNA levels, indicating a protective role.
• These RNP aggregates obstruct material transport, prolonging oogenesis and enhancing 3S18 propagation.

Conclusions:

• The 3S18 retrotransposon utilizes RNP aggregate formation to impact host oogenesis and promote its own replication.
• 3S18 aggregates interfere with host cellular transport, creating a more favorable environment for its propagation.
• This study reveals a novel mechanism of parasitic element interaction with host development, with implications for understanding viruses and other mobile elements.