Kwon HJ and Chung HM (2003), Yin Yang 1, a vertebrate polycomb group gene, r...

XB-ART-5108

Biochem Biophys Res Commun 2003 Jul 11;3064:1008-13. doi: 10.1016/s0006-291x(03)01071-4.

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Yin Yang 1, a vertebrate polycomb group gene, regulates antero-posterior neural patterning.

Kwon HJ , Chung HM .

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Polycomb group (PcG) genes are required for the stable repression of the homeotic genes and other developmentally regulated genes. Yin Yang 1 (YY1), a vertebrate homolog of the Drosophila PcG pleiohomeotic (Pho), is a multifunctional protein that can act as a repressor or activator of transcription. Xenopus YY1 (XYY1) protein was localized in the central nervous system (CNS), particularly anterior neural tube of tailbud stage embryos. To elucidate the role of endogenous XYY1, loss-of-function studies were performed using XYY1 antisense morpholino oligonucleotide (XYY1 MO). Inhibition of XYY1 function resulted in embryos with antero-posterior axial patterning defects and reduction of head structures. XYY1 MO also reduced the expression of En2, a midbrain/hindbrain junction marker, which was rescued by co-injection of XYY1 mRNA. However, XYY1 MO-injection did not affect the expression of HoxB9, a spinal cord marker. These results suggest that YY1 controls antero-posterior patterning of the CNS during Xenopus embryonic development.

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Species referenced: Xenopus laevis
Genes referenced: egr2 en2 hoxb9 ncam1 otx2 yy1
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	Fig. 1. Spatial distribution of YY1 protein in Xenopus embryo. XYY1 proteins were analyzed by immunostaining. (A,C) Lateral views of late tailbud stage embryos (stage 32 (A) and 36 (C)). (B) Neural tube (top) and notochord (bottom) isolated from (A). Both are oriented anterior to posterior, left to right. There is strong staining in the anterior region of the neural tube and eye. (D) Tailbud stage embryo stained with MZ15, notochord specific antibody. (E) Neural tube and notochord isolated from (D). (F) No primary antibody as a negative control. nt, neural tube; nc, notochord; ev, eye vesicle.
	Fig. 2. Phenotypic effects of loss-of-XYY1 function. Embryos were injected at the two-cell stage into each blastomere with the control morpholino (Control MO; A, C, E) or XYY1-specific antisense morpholino oligonucleotide (YY1 MO; B, D, F) Injected embryos were fixed when sibling embryos reached stage 12.5 (A,B), stage 32 (C,D), and stage 41 (E,F). At 14.5 h post-fertilization, control MO-injected embryo was at stage 12.5, small yolk plug stage (A), while XYY1 MO-injected embryo resembled normal embryos at stage 12, medium yolk plug stage (B). (D,F) XYY1 MO injection severely affects head structures and A-P axis patterning.
	Fig. 3. Effects of the XYY1 MO-injection on the expression of neural markers. (A,B) Molecular analysis of control MO (lane 1), XYY1 MO-injected embryos (lane 2), and uninjected embryos (lane 4) by quantitative RT-PCR assay at stage 13.5 (A) and stage 19 (B). XYY1 MO was injected into both blastomeres at the two-cell stage (3.8 ng/cell). Minus RT ()RT) indicates PCR amplification without reverse transcriptase as a negative control. The constitutively expressed ornithine decarboxylase (ODC) transcript was used for normalizing results (n ¼ 3 independent experiments; error bars, SEM).
	Fig. 4. Rescue of XYY1-MO induced effects by the injection of XYY1 mRNA. (A,B) XYY1 MO (38 ng) was rescued by coinjection with XYY1 mRNA (1 ng). Lateral views of standard control MO-, XYY1 MO+XYY1 mRNA-injected embryos at stage 32 (A) and stage 41 (B). (C) RT-PCR analysis of stage 13.5 embryo samples. Note the restored expression of En2 gene in embryos injected with 7.6 ng XYY1 MO and 500 pg XYY1 mRNA (lane 3) compared with XYY1 MO-injected embryos (lane 2).