Telomere Function and the G-Quadruplex Formation are Regulated by hnRNP U

Area of Science:

• Molecular Biology
• Genetics
• Biochemistry

Background:

• Telomeric G-quadruplexes are well-characterized in vitro.
• Their in vivo function and protein interactions in mammalian cells remain unclear.
• Heterogeneous ribonucleoprotein U (hnRNP U) is a potential G-quadruplex binding protein.

Purpose of the Study:

• To investigate the role of hnRNP U as a G-quadruplex binding protein in human cell lines.
• To determine if hnRNP U associates with telomeres and its potential telomere-related functions.
• To elucidate the in vivo interactions and functions of hnRNP U at telomeres.

Main Methods:

• Immunoprecipitation
• DNA pull-down assays
• Binding assays
• Western blots

Main Results:

• hnRNP U was identified as a G-quadruplex binding protein.
• Endogenous hnRNP U was found to associate with telomeres.
• The C-terminus of hnRNP U specifically binds telomeric G-quadruplexes.
• hnRNP U binding to telomeric oligonucleotides is influenced by telomere repeat containing RNA (TERRA).
• hnRNP U prevents replication protein A (RPA) accumulation at telomeres.

Conclusions:

• hnRNP U is a G-quadruplex binding protein that interacts with telomeres in vivo.
• hnRNP U plays a role in regulating telomere accessibility.
• The interaction of hnRNP U with telomeres suggests a G-quadruplex-mediated regulation mechanism.
• hnRNP U has significant functions in telomere biology.