Search research articles

ABOUT JoVE

Overview Leadership Blog JoVE Help Center

AUTHORS

Publishing Process Editorial Board Scope & Policies Peer Review FAQ Submit

LIBRARIANS

Testimonials Subscriptions Access Resources Library Advisory Board FAQ

RESEARCH

JoVE Journal Methods Collections JoVE Encyclopedia of Experiments Archive

EDUCATION

JoVE Core JoVE Business JoVE Science Education JoVE Lab Manual Faculty Resource Center Faculty Site

Terms & Conditions of Use

Related Concept Videos

Telomeres and Telomerase

Telomeres and Telomerase

In eukaryotic DNA replication, a single-stranded DNA fragment remains at the end of a chromosome after the removal of the final primer. This section of DNA cannot be replicated in the same manner as the rest of the strand because there is no 3’ end to which the newly synthesized DNA can attach. This non-replicated fragment results in gradual loss of the chromosomal DNA during each cell duplication. Additionally, it can induce a DNA damage response by enzymes that recognize single-stranded...

Telomeres and Telomerase

Telomeres and Telomerase

Chromosome Structure

Chromosome Structure

A functional eukaryotic chromosome must contain three elements: a centromere, telomeres, and numerous origins of replication.
The centromere is a DNA sequence that links sister chromatids. This is also where kinetochores, protein complexes to which spindle microtubules attach, are constructed after the chromosome is replicated. The kinetochores allow the spindle microtubules to move the chromosomes within the cell during cell division.
Telomeres consist of non-coding repetitive nucleotide...

Chromosome Structure

Chromosome Structure

Chromosome Replication

Chromosome Replication

Before a cell can divide, it must accurately replicate all of its chromosomes, including the DNA and its associated histone and non-histone proteins. This process begins at numerous origins of replication during the S phase of the cell cycle in each of a cell’s chromosomes simultaneously. Certain nucleotides can act as origins of replication, but these sequences are not well defined - especially in complex, multi-cellular, eukaryotic species. The length of DNA that spans an origin...

Lampbrush Chromosomes

Lampbrush Chromosomes

In 1882, Flemming observed lampbrush chromosomes (LBC) in salamander eggs. Later in 1892, Rückert observed LBCs in shark egg cells and coined the term "lampbrush chromosomes" because they looked like brushes used to clean kerosene lamps.
LBCs are made up of two pairs of conjugating homologous chromatids. Each chromatid consists of alternatively positioned regions of condensed-inactive chromatin and loosely placed-active side loops, which can be contracted and extended. The loops...

You might also read

Related Articles

Articles linked to this work by shared authors, journal, and citation graph.

Sort by

Same author

Distinct ATRX functions cooperate with 9-1-1 and CST complexes to safeguard replication and telomere integrity.

Nature structural & molecular biology·2026

Same author

Regulation of olfactory chloride and cyclic nucleotide-gated channels by cholesterol.

The Journal of general physiology·2026

Same author

Telomere heterochromatin-mediated compartmentalization: Where ALT begins.

Trends in cell biology·2026

Same author

T-loop dynamics: telomere structure shapes cell fate decisions.

Trends in cell biology·2026

Same author

Correction: Targeted Therapy of TERT-Rearranged Neuroblastoma with BET Bromodomain Inhibitor and Proteasome Inhibitor Combination Therapy.

Clinical cancer research : an official journal of the American Association for Cancer Research·2026

Same author

Telomeres and Telomerase.

Cold Spring Harbor perspectives in biology·2026

Search research articles

Related Experiment Video

Updated: Feb 7, 2026

Fluorescence In Situ Hybridization on DNA Halo Preparations to Reveal Whole Chromosomes, Telomeres and Gene Loci

Fluorescence In Situ Hybridization on DNA Halo Preparations to Reveal Whole Chromosomes, Telomeres and Gene Loci

Published on: March 4, 2021

Telomere Loop Dynamics in Chromosome End Protection.

David Van Ly¹, Ronnie Ren Jie Low², Sonja Frölich²

¹Genome Integrity Unit, Children's Medical Research Institute, University of Sydney, Westmead, NSW 2145, Australia; School of Medicine, The University of Notre Dame Australia, Sydney, NSW 2010, Australia.

|July 24, 2018

Summary

Telomere loops (t-loops) regulate ATM activation, a key factor in cell aging and tumor suppression. Structural changes from t-loops to linear telomeres trigger ATM, independent of DNA repair pathways like NHEJ.

Keywords:

ATM Aurora B kinase DNA damage response TRF2 mitosis non-homologous end joining super-resolution microscopy telomere loops telomere protection telomeres

More Related Videos

Examination of the Telomere G-overhang Structure in Trypanosoma brucei

Examination of the Telomere G-overhang Structure in Trypanosoma brucei

Published on: January 26, 2011

Chemical Dimerization-Induced Protein Condensates on Telomeres

Chemical Dimerization-Induced Protein Condensates on Telomeres

Published on: April 12, 2021

Related Experiment Videos

Last Updated: Feb 7, 2026

Fluorescence In Situ Hybridization on DNA Halo Preparations to Reveal Whole Chromosomes, Telomeres and Gene Loci

Fluorescence In Situ Hybridization on DNA Halo Preparations to Reveal Whole Chromosomes, Telomeres and Gene Loci

Published on: March 4, 2021

Examination of the Telomere G-overhang Structure in Trypanosoma brucei

Examination of the Telomere G-overhang Structure in Trypanosoma brucei

Published on: January 26, 2011

Chemical Dimerization-Induced Protein Condensates on Telomeres

Chemical Dimerization-Induced Protein Condensates on Telomeres

Published on: April 12, 2021

Area of Science:

Cellular biology
Molecular genetics
Genomics

Background:

Telomeres protect chromosome ends and are crucial for cellular aging and tumor suppression.
ATM (Ataxia-Telangiectasia Mutated) is a critical kinase in the DNA damage response (DDR).
The structural organization of telomeres, including telomere loops (t-loops), influences DDR and DNA repair, particularly non-homologous end joining (NHEJ).

Purpose of the Study:

To investigate how telomere macromolecular structure impacts ATM regulation.
To determine if ATM activation is linked to telomere fusion via NHEJ.
To elucidate the role of t-loops and TRF2 in controlling ATM activity and telomere stability.

Main Methods:

Super-resolution microscopy to visualize telomere structure and ATM activation.
Genetic manipulation of TRF2 to study its role in t-loop formation and ATM suppression.
Cell cycle arrest (G1) to assess telomere fusion resistance during active NHEJ.

Main Results:

ATM activation at telomeres correlates with a structural transition from t-loops to linearized telomeres.
The TRFH domain of TRF2 is essential for t-loop formation and suppresses ATM activity.
ATM activation and telomere linearization are separable from NHEJ-mediated telomere fusion.
Linear, DDR-positive telomeres can resist fusion even when NHEJ is active.

Conclusions:

Telomere loops (t-loops) function as conformational switches regulating ATM activation independently of telomere fusion mechanisms.
TRF2's TRFH domain plays a critical role in maintaining t-loops and suppressing ATM.
These findings reveal a novel mechanism by which telomere structure controls DDR signaling and inhibits NHEJ, impacting cell aging and cancer.