DNAm control of telomere length
Telomeric regions, comprising telomeres and subtelomeres, are typically embedded in constitutive heterochromatin. In Arabidopsis thaliana, however, telomeres lack DNA methylation and other repressive marks, while adjacent subtelomeres are heterochromatic and heavily methylated. This bimodal chromatin organization challenges the classical view of uniformly heterochromatic telomeres and suggests a distinct regulatory architecture. Notably, Arabidopsis mutants defective in DNA methylation exhibit telomere shortening, implicating chromatin state in telomere maintenance. However, we show here that these mutants do not display defects in telomere recombination control, indicating that telomere shortening does not necessarily lead to telomere dysfunction. We also demonstrate that targeted demethylation of the chromosome arm 1L subtelomere using the SunTag-TET1 system specifically shortens the 1L telomere, without affecting others. This effect is abolished when a catalytically inactive TET1 is used, confirming a causal role for DNA methylation. These findings provide direct evidence that subtelomeric DNA methylation regulates telomere length, revealing a previously uncharacterized epigenetic mechanism of telomere control.
Telomeric regions, comprising telomeres and subtelomeres, are typically embedded in constitutive heterochromatin. In Arabidopsis thaliana, however, telomeres lack DNA methylation and other repressive marks, while adjacent subtelomeres are heterochromatic and heavily methylated. This bimodal chromatin organization challenges the classical view of uniformly heterochromatic telomeres and suggests a distinct regulatory architecture. Notably, Arabidopsis mutants defective in DNA methylation exhibit telomere shortening, implicating chromatin state in telomere maintenance. However, we show here that these mutants do not display defects in telomere recombination control, indicating that telomere shortening does not necessarily lead to telomere dysfunction. We also demonstrate that targeted demethylation of the chromosome arm 1L subtelomere using the SunTag-TET1 system specifically shortens the 1L telomere, without affecting others. This effect is abolished when a catalytically inactive TET1 is used, confirming a causal role for DNA methylation. These findings provide direct evidence that subtelomeric DNA methylation regulates telomere length, revealing a previously uncharacterized epigenetic mechanism of telomere control.
Institute of Vegetal Biochemistry and Photosynthesis