[Mouse centromeric tandem repeats in silico and in situ]

Area of Science:

• Genomics
• Molecular Biology
• Epigenetics

Context:

• Centromeres are critical for chromosome segregation during cell division.
• Satellite DNA, including mouse minor satellite (MiSat) and major satellite (MaSat), forms the bulk of centromeric and pericentromeric heterochromatin.
• The composition and organization of centromeric DNA, particularly the role of repetitive elements, are not fully understood.

Purpose:

• To identify and characterize novel sequence elements associated with mouse centromeric (CEN) and pericentromeric (peri-CEN) regions.
• To investigate the interactions between satellite DNA (MiSat, MaSat) and other repetitive elements, such as retroelements (LINE, IAP).
• To explore the potential role of retroelements in centromere structure and function.

Summary:

• Searched whole genome shotgun (WGS) database for mouse MiSat and MaSat sequences, identifying monotonous arrays and transitions.
• Discovered novel contacts between MiSat and LINE/IAP retroelements, and MaSat and other tandem repeats.
• Experimental validation using fluorescence in situ hybridization (FISH) on extended chromatin fibers (fiberFISH) confirmed MiSat/IAP associations with centromeres and chromosome arms, suggesting retroelements are integral to centromere composition.

Impact:

• Provides new insights into the complex genomic architecture of centromeres.
• Suggests that retroelements, previously considered junk DNA, are essential components of higher eukaryotic centromeres.
• Opens avenues for further research into the functional significance of retroelement-centromere interactions in genome stability and evolution.