Visualization of interphase chromosomes in postmitotic cells of the human brain by multicolour banding (MCB)

Abstract

Molecular cytogenetics offers the unique possibility of investigating numerical and structural chromosomal aberrations in interphase nuclei of somatic cells. Previous fluorescence in-situ hybridization (FISH) investigations gave hints of numerical chromosomal imbalances in the human brain, present as low-level mosaicism. However, as precise identification of aneuploidy rates in somatic tissues faces major difficulties due to the limitations of FISH using whole chromosome painting or centromeric probes, in this study low-level mosaicism in the human brain was addressed for the first time using microdissection-based multicolour banding (MCB) probe sets. We demonstrated that MCB is suitable for this application and leads to more reliable results than the use of centromeric probes in parallel on the same samples. Autosomes and the active X chromosome appear as discrete metaphase chromosome-like structures, while the inactive X chromosome is condensed in more than 95% of interphase nuclei. The frequency of stochastic aneuploidy was found to be 0.2-0.5% (mean 0.35%) per autosome pair, 2% for the X chromosome in the female brain, and 0.4% in the male brain, giving a cumulative frequency of aneuploidy of approximately 10% in the adult brain. Moreover, MCB as well as multi-probe FISH using centromeric probes revealed associated signals in a large proportion of brain cells (10-40%). While co-localized signals could not be discriminated from numerical chromosome imbalances after FISH using centromeric probes, interphase MCB allows such differentiation. In summary, MCB is the only approach available at present that provides the possibility of characterizing the chromosomal integrity of arbitrary interphase cell populations. Thus, cytogenetics is no longer limited in its application to dividing cells, which is a great step forward for brain research.

Chromosome distribution in human sperm – a 3D multicolor banding-study

“…However, our own multicolor banding (MCB) based studies [8] showed, that the chromosome shape is not lost in the interphase nucleus and one can even identify interphase chromosomes instead of only chromosome territory [9][10][11]. MCB is the only approach available at present that provides the possibility of characterizing the chromosomal integrity of arbitrary interphase cell populations [12,13]. It is still a matter of discussion what influences more the nuclear position of chromosomes: chromosome size or gene density.…”

“…It is still a matter of discussion what influences more the nuclear position of chromosomes: chromosome size or gene density. It has been repeatedly shown that small chromosomes preferentially locate close to the center of the nucleus, while large chromosomes can be found in the nuclear periphery of human fibroblasts [11][12][13][14][15]. Nonetheless, also evidence for a gene density-correlated radial arrangement of chromosomes in the nucleus was provided [16].…”

To see an interphase chromosome or: How a disease can be associated with specific nuclear genome organization

“…Its application allows the analysis of chromosome (chromosomal loci) positioning in interphase and chromosomal associations at "subchromosomal" resolution in a given nucleus (for more details see [4][5][6][7][8][9]). Evidently, analyzing each chromosomal region is likely to provide more reliable information in contrast to analyzing homogenously painted chromosomes or a single chromosomal region.…”

“…To solve this problem, a technique providing for simultaneous visualization of the whole chromosome and its regions in a given nucleus has appeared to be required [3]. The development of interphase chromosome-specific multicolor banding (ICS-MCB) has led the way towards the high-resolution interphase cytogenetic analysis for Visualization of interphase chromosomes studying chromosomal numbers, structure and spatial arrangement within the nucleus [4][5][6][7]. Using ICS-MCB, chromosome architecture was evaluated in some tissues at "subchromosomal" resolution and specific positioning of chromosomal loci was shown to be linked to generation and behavior of rearranged chromosomes in interphase [8][9][10].…”

Genomic Instability in the Brain: Etiology, Pathogenesis and New Biological Markers of Psychiatric Disorders

“…После рождения уровень CIN в клетках головного мозга значительно снижается, по-видимому, за счет запрограм-мированной смерти аномальных клеток с хромосомными и геномными нарушениями. Это приводит, по крайней мере, к тройному уменьшению уровня нестабильности (анеуплоидии) в клетках ЦНС после рождения [6,[9][10][11]. Однако, сохраняясь благодаря ошибкам при клеточном (митотическом) делении и последующем отборе нормальных и пораженных (анеуплоидных) клеток, такая нестабильность может дать начало различным патоло-гическим состояниям.…”