Inherent instability of simple DNA repeats shapes an evolutionarily stable distribution of repeat lengths.

Using the Telomere-to-Telomere reference, we assembled the distribution of simple repeat lengths present in the human genome. Analyzing over two hundred mammalian genomes, we found remarkable consistency in the shape of the distribution across evolutionary epochs. All observed genomes harbor an excess of long repeats, which are prone to developing into repeat expansion disorders.

Triplex H-DNA structure: the long and winding road from the discovery to its role in human disease.

H-DNA is an intramolecular DNA triplex formed by homopurine/homopyrimidine mirror repeats. Since its discovery, the field has advanced from characterizing the structure to discovering its existence and role . H-DNA interacts with cellular machinery in unique ways, stalling DNA and RNA polymerases and causing genome instability.

Stabilization of expandable DNA repeats by the replication factor Mcm10 promotes cell viability.

Trinucleotide repeats, including Friedreich's ataxia (GAA) repeats, become pathogenic upon expansions during DNA replication and repair. Here, we show that deficiency of the essential replisome component Mcm10 dramatically elevates (GAA) repeat instability in a budding yeast model by loss of proper CMG helicase interaction. Supporting this conclusion, live-cell microscopy experiments reveal increased replication fork stalling at the repeat in mcm10-1 cells.

Electrophoretic Analysis of Replication Through Structure-Prone DNA Repeats Within the SV40-Based Human Episome.

Two-dimensional neutral/neutral gel-electrophoresis (2DGE) emerged as a benchmark technique to analyze DNA replication through natural impediments. This protocol describes how to analyze replication fork progression through structure-prone, expandable DNA repeats within the simian virus 40 (SV40)-based episome in human cells. In brief, upon plasmid transfection into human cells, replication intermediates are isolated by the modified Hirt protocol and treated with the DpnI restriction enzyme to remove non-replicated DNA.