The many faces of the helicase RTEL1 at telomeres and beyond

Regulator of telomere elongation 1 (RTEL1) is known as a DNA helicase that is important for telomeres and genome integrity. However, the diverse phenotypes of RTEL1 dysfunction, the wide spectrum of symptoms caused by germline RTEL1 mutations, and the association of RTEL1 mutations with cancers suggest that RTEL1 is a complex machine that interacts with DNA, RNA, and proteins, and functions in diverse cellular pathways. We summarize the proposed functions of RTEL1 and discuss their implications for telomere maintenance. Studying RTEL1 is crucial for understanding the complex interplay between telomere maintenance and other nuclear pathways, and how compromising these pathways causes telomere biology diseases, various aging-associated pathologies, and cancer.