Methylation imprinting was observed of mouse mo-2 macrosatellite on the pseudoautosomal region but not on chromosome 9

Abstract

Mouse mo-2 macrosatellites consisting of 31-bp tandem repeat units are mainly located at two loci in the C57BL/6 genome, one being at the centromere-distal telomeric region of chromosome 9 and the other at the pseudoautosomal (PA) region of chromosomes X and Y. The two clusters constitute approximately 300 kb and 150 kb, respectively. Southern analysis of a methylation-sensitive enzyme, HpaII-digested DNA showed that the mo-2 macrosatellites are detected as more than 30 polymorphic bands. Comparison of those bands between reciprocally crossed F1 mice revealed that approximately 20% of the allele-specific fragments exhibit different band intensities depending on the sex of the parent of origin. The differential methylation is observed in the mo-2 macrosatellite on the PA region but not in that on chromosome 9. Several fragments including the 3.4-kb fragment without internal HpaII site are more clearly detected when paternally derived, suggesting that the male-derived macrosatellite is undermethylated. Interestingly, the difference is much more remarkable in inter-subspecific F1 mice between C57BL/6 and MSM than F1 between C57BL/6 and C3H/He. This suggests the presence of a modifier(s) that affect(s) the methylation of mo-2 in the MSM genome.

Ensuring meiotic DNA break formation in the mouse pseudoautosomal region

“…BLAST searches detected additional mo-2 clusters at the noncentromeric ends of chr9 and chr13 in the mm10 genome assembly and chr4 from the Celera assembly (Fig. 3A), matching the reported distribution (36,37). Although these autosomal clusters are only 2 to 8 kb in the assemblies, their copy number is likely underrepresented because they lie adjacent to gaps.…”

“…Self-aligning the PARb probe sequence illustrated its highly repetitive nature, including a central ~20-kb tandem array of a minisatellite called mo-2, with a 31-bp GC-rich repeat (36,37) (Fig. 3A).…”

“…If so, we reasoned that reducing mo-2 copy number might reduce the amount of RMMAI proteins. To test this prediction, we took advantage of a natural experiment afforded by mouse strain diversity, namely, the fact that the Mus musculus molossinus subspecies has substantially lower mo-2 copy number on the PAR and autosomes (37). The wild-derived M. m. molossinus strain MSM/MsJ (hereafter MSM) showed less hybridization signal with the mo-2 FISH probe as expected, but importantly also gave lower intensity of REC114 immunostaining in blobs compared to B6 ( fig.…”

“…Mo-2 oligonucleotide probes were synthetized by Integrated DNA Technologies, with 6-FAM or TYE™ 665 fluorophores added to both 5¢ and 3¢ ends of the oligonucleotide. The DNA sequence was designed based on the previously defined consensus sequence (37), and the probe was used at a final concentration of 10 pmol/µl in hybridization buffer without Cot-1 DNA. The Y-chromosome paint probe was purchased from IDLabs and used at 1:30 dilution in hybridization buffer without Cot-1 DNA.…”

Unstable transmission of the RS447 human megasatellite tandem repetitive sequence that contains the USP17 deubiquitinating enzyme gene

“…Various types of repetitive sequences have been reported and categorized according to (in addition to the primary sequence) repeat-unit length, the number of repeats, and their mapping in the genome. The headto-tail tandem repetitive sequences, such as microsatellite (Litt and Luty 1989), minisatellite (Jeffreys et al 1985), or variable number of tandem repeat (Nakamura et al 1987), macrosatellite (Kodama et al 1987;Epstein et al 1987;Zhu et al 1990; Giacalone et al 1992; van Deutekom et al 1993;Lopez et al 1994;Takahashi et al 1994), and megasatellite DNA (Gondo et al 1998), are highly polymorphic, repetitive DNA sequences postulated as making a substantial contribution to genomic instability because of their high mutation frequencies. Several hypothetical mutation models for repetitive DNA have been proposed following the extensive analyses of micro-or minisatellite DNA sequences.…”