Se. Quaggin et al., ANTISENSE OLIGONUCLEOTIDES TO CUX-1, A CUT-RELATED HOMEOBOX GENE, CAUSE INCREASED APOPTOSIS IN MOUSE EMBRYONIC KIDNEY CULTURES, The Journal of clinical investigation, 99(4), 1997, pp. 718-724
Cux-1 is a murine homeobox gene that is highly and transiently express
ed in the developing kidney. To further evaluate the role of Cux-1 in
mammalian kidney development, organotypic cultures of embryonic mouse
kidney were incubated with phosphorothioate-coupled antisense Cux-1 ol
igonucleotides (ODNs) in the presence of cationic liposomes. Inhibitio
n of Cux-1 expression by antisense ODNs was verified by reverse transc
ription-PCR. Metanephroi that were incubated with antisense Cu-l ODNs
were 23% smaller than metanephroi that were incubated with sense Cux-1
ODNs. Morphologic analysis of metanephroi that were treated with anti
sense Cux-1 ODNs revealed that ureteric buds and induced epithelial st
ructures were present. However, extensive areas of cell. death contain
ing shrunken cells with pyknotic nuclei were also evident. The presenc
e of increased apoptosis was verified by ultrastructural and terminal
transferase-mediated dUTP nick end labeling analyses. Two different an
tisense Cux-1 ODNs targeting either the translation start codon or the
homeobox produced increased apoptosis. In contrast, metanephroi incub
ated with sense ODNs exhibited only occasional apoptotic cells. We con
clude that the presence of antisense Cux-1 ODNs does not block nephron
induction, but results instead in increased apoptosis. Proper regulat
ion of Cux-1 expression may be necessary for normal kidney development
.