Homologous Association of Oppositely Imprinted Chromosomal Domains

Abstract

Human chromosome 15q11-q13 encompasses the Prader-Willi syndrome (PWS) and the Angelman syndrome (AS) loci, which are subject to parental imprinting, a process that marks the parental origin of certain chromosomal subregions. A temporal and spatial association between maternal and paternal chromosomes 15 was observed in human T lymphocytes by three-dimensional fluorescence in situ hybridization. This association occurred specifically at the imprinted 15q11-q13 regions only during the late S phase of the cell cycle. Cells from PWS and AS patients were deficient in association, which suggests that normal imprinting involves mutual recognition and preferential association of maternal and paternal chromosomes 15.

Epigenetic reprogramming of the human H19 gene in mouse embryonic cells does not erase the primary parental imprint

“…It has been reported that a temporal association of homologous chromosomes occurs specifically at imprinted loci in human somatic cells, suggesting that allelic interaction may have a role in the allele-specific expression of imprinted genes (LaSalle & Lalande 1996). Our study is based on human mono-chromosomal hybrids, and therefore demonstrates that the imprint mark can function effectively without both human alleles.…”

Intergenic transcription and transinduction of the human β-globin locus

“…The two brown alleles are paired and the heterochromatin insertion in one causes both alleles to associate with the heterochromatic centromere, suppressing brown expression (Csink and Henikoff 1996;Dernburg et al 1996). Transient pairing of mammalian chromosomes has also been described (LaSalle and Lalande 1996), although it remains to be determined whether such pairing between chromosomal loci is used to regulate transcription.…”

Micrococcal nuclease (endonuclease) digestion causes apoptosis and mitotic catastrophe with interphase chromosome condensation in human Chang liver cells

“…Figure 6C-E show interphasic chromosome condensation forms. Figure 6C shows condensed chromosomes in parallel alignment typical of homologous chromosome pairing in interphase cells (LaSalle and Lalande, 1996), and a common feature in premature chromosome condensations of interphase cells induced by mitotic-interphase cell fusions (Rao, 1977;Ibid, 1990). Interphasic chromosome condensations are also characterized by their tendency to surround nucleolar areas producing ringformations, and shown in Figure 6C) (arrowed).…”