MxB inhibits long interspersed element type 1 retrotransposition

Area of Science:

• Genetics
• Molecular Biology
• Cellular Biology

Background:

• Long interspersed element type 1 (LINE-1) is an autonomous transposable element in the human genome.
• LINE-1 insertions can disrupt gene function, leading to genetic diseases.
• Cells possess mechanisms to control LINE-1 activity.

Purpose of the Study:

• To investigate the role of myxovirus resistance protein B (MxB) in controlling LINE-1 mobilization.
• To elucidate the molecular mechanisms by which MxB restricts LINE-1 activity.

Main Methods:

• Assessed MxB's requirement for LINE-1 restriction using its N-terminal nuclear localization signal, GTPase activity, and oligomerization ability.
• Investigated the association between MxB and LINE-1 ORF1p.
• Examined the role of G3BP1 and TIA1 in MxB-mediated LINE-1 inhibition through knockdown experiments.

Main Results:

• MxB restricts LINE-1 mobilization, dependent on its N-terminal nuclear localization signal, GTPase activity, and oligomerization.
• MxB associates with LINE-1 ORF1p.
• MxB sequesters ORF1p into G3BP1-containing cytoplasmic granules, a process dependent on stress granule components like G3BP1 and TIA1.

Conclusions:

• MxB utilizes stress granule components to sequester LINE-1 proteins in cytoplasmic granules.
• This sequestration mechanism effectively prevents LINE-1 from accessing the nucleus for retrotransposition.
• MxB represents a cellular mechanism for controlling retroelement mobility.