Biological dark matter - ‘junk DNA’ involved in aging and tumorigenesis

A group of scientists at Washington State University (PNAS June 29, 2021 118 (26) e2019043118), identified the involvement of an intronic variable number tandem repeat sequence (VNTR), VNTR2-1 required for the transcription of the human telomerase reverse transcriptase (hTERT) gene. The unique role of telomerase enzyme in producing telomeres protects the DNA ends during cell division. But this is also the reason for uncontrolled cancer proliferation. Reduced telomerase activity could result in telomere shortening and cellular senescence. Positive regulation of hTERT gene by VNTR2-1 points out the importance of telomerase activity in aging and cancer. They reported that genomic deletion of VNTR2-1 in MelJuSo melanoma cells reduced hTERT transcription thereby leading to cellular senescence and impairment of xenograft tumor growth. Their findings inferred this polymorphic element to be a missing link in telomere homeostasis and age-related diseases.