Co-evolving infectivity and expression patterns drive the diversification of endogenous retroviruses

Area of Science:

• Molecular Biology
• Evolutionary Biology
• Genetics

Background:

• Transposable elements significantly impact host genome evolution.
• Mechanisms driving transposable element diversification are not fully understood.
• Endogenous retroviruses (ERVs) are infectious LTR-retrotransposons encoding an Envelope protein.

Purpose of the Study:

• To elucidate the evolutionary principles governing insect ERV diversification.
• To investigate the co-evolution of ERV infectivity and spatiotemporal expression.
• To understand the molecular basis of ERV adaptation and loss of infectivity.

Main Methods:

• Comparative genomic analyses across Drosophila species.
• Experimental studies of transposon replication cycles.
• Investigation of the piRNA pathway and its interaction with ERVs.

Main Results:

• ERVs possess cis-regulatory sequences enabling function across ovarian cell types.
• Infectious ERVs express in somatic cells to infect the germline; non-infectious ERVs express only in the germline.
• Co-evolutionary changes in the piRNA pathway reflect ERV expression niches and functional significance.

Conclusions:

• ERV infectivity and spatiotemporal expression are tightly co-evolving traits.
• The piRNA pathway plays a crucial role in integrating ERV sequence and expression information.
• Fundamental mechanisms driving ERV-host co-evolution and LTR sequence diversification have been uncovered.