Segmental trisomy of chromosome 17: a mouse model of human aneuploidy syndromes.
Triplication of whole autosomes or large autosomal segments is detrimental to the development of a mammalian embryo. The trisomy of human chromosome (Chr) 21, known as Down's syndrome, is regularly associated with mental retardation and a variable set of other developmental anomalies. Several mouse models of Down's syndrome, triplicating 33-104 genes of Chr16, were designed in an attempt to analyze the contribution of specific orthologous genes to particular developmental features. However, a recent study challenged the concept of dosage-sensitive genes as a primary cause of an abnormal phenotype. To distinguish between the specific effects of dosage-sensitive genes and nonspecific effects of a large number of arbitrary genes, we revisited the mouse Ts43H/Ph segmental trisomy. It encompasses >310 known genes triplicated within the proximal 30 megabases (Mb) of Chr17. We refined the distal border of the trisomic segment to the interval bounded by bacterial artificial chromosomes RP23-277B13 (location 29.0 Mb) and Cbs gene (location 30.2 Mb). The Ts43H mice, viable on a mixed genetic background, exhibited spatial learning deficits analogous to those observed in Ts65Dn mice with unrelated trisomy. Quantitative analysis of the brain expression of 20 genes inside the trisomic interval and 12 genes lying outside on Chr17 revealed 1.2-fold average increase of mRNA steady-state levels of triplicated genes and 0.9-fold average down-regulation of genes beyond the border of trisomy. We propose that systemic comparisons of unrelated segmental trisomies, such as Ts65Dn and Ts43H, will elucidate the pathways leading from the triplicated sequences to the complex developmental traits.
Vacík
Tomás
T
Institutes of Molecular Genetics and Physiology, Academy of Sciences of the Czech Republic, 14220 Prague, Czech Republic.
Ort
Michael
M
Gregorová
Sona
S
Strnad
Petr
P
Blatny
Radek
R
Conte
Nathalie
N
Bradley
Allan
A
Bures
Jan
J
Forejt
Jirí
J
D000782:Aneuploidy; D000818:Animals; D001921:Brain / Q000378:metabolism; D019457:Chromosome Breakage / Q000235:genetics; D025063:Chromosome Disorders / Q000235:genetics* / Q000378:metabolism / Q000523:psychology; D022202:Chromosomes, Artificial, Bacterial / Q000235:genetics; D004195:Disease Models, Animal; D004314:Down Syndrome / Q000235:genetics; D018628:Gene Dosage; D015870:Gene Expression; D006801:Humans; D018782:Maze Learning; D051379:Mice; D008815:Mice, Inbred Strains; D008817:Mice, Mutant Strains; D010641:Phenotype; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D013577:Syndrome; D014178:Translocation, Genetic; D014314:Trisomy
D012333:RNA, Messenger