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Dual functions of ASCIZ in the DNA base damage response and pulmonary organogenesis.

Jurado S, Smyth I, van Denderen B, Tenis N, Hammet A, Hewitt K, Ng JL, McNees CJ, Kozlov SV, Oka H, Kobayashi M, Conlan LA, Cole TJ, Yamamoto K, Taniguchi Y, Takeda S, Lavin MF, Heierhorst J - PLoS Genet. (2010)

Bottom Line: Unexpectedly, Asciz-deficient embryos also exhibit severe respiratory tract defects with complete pulmonary agenesis and severe tracheal atresia.Comparison of phenotypes suggests that ASCIZ functions between Wnt2-2b/ß-catenin and FGF10/FGF-receptor 2b signaling pathways in the mesodermal/endodermal crosstalk regulating early respiratory development.We also find that ASCIZ can activate expression of reporter genes via its SQ/TQ-cluster domain in vitro, suggesting that it may exert its developmental functions as a transcription factor.

View Article: PubMed Central - PubMed

Affiliation: St. Vincent's Institute of Medical Research, Fitzroy, Australia.

ABSTRACT
Zn²(+)-finger proteins comprise one of the largest protein superfamilies with diverse biological functions. The ATM substrate Chk2-interacting Zn²(+)-finger protein (ASCIZ; also known as ATMIN and ZNF822) was originally linked to functions in the DNA base damage response and has also been proposed to be an essential cofactor of the ATM kinase. Here we show that absence of ASCIZ leads to p53-independent late-embryonic lethality in mice. Asciz-deficient primary fibroblasts exhibit increased sensitivity to DNA base damaging agents MMS and H2O2, but Asciz deletion knock-down does not affect ATM levels and activation in mouse, chicken, or human cells. Unexpectedly, Asciz-deficient embryos also exhibit severe respiratory tract defects with complete pulmonary agenesis and severe tracheal atresia. Nkx2.1-expressing respiratory precursors are still specified in the absence of ASCIZ, but fail to segregate properly within the ventral foregut, and as a consequence lung buds never form and separation of the trachea from the oesophagus stalls early. Comparison of phenotypes suggests that ASCIZ functions between Wnt2-2b/ß-catenin and FGF10/FGF-receptor 2b signaling pathways in the mesodermal/endodermal crosstalk regulating early respiratory development. We also find that ASCIZ can activate expression of reporter genes via its SQ/TQ-cluster domain in vitro, suggesting that it may exert its developmental functions as a transcription factor. Altogether, the data indicate that, in addition to its role in the DNA base damage response, ASCIZ has separate developmental functions as an essential regulator of respiratory organogenesis.

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Late gestational growth defect of Asciz-deficient embryos.(A) Embryo weights of WT, heterozygotes and Asciz-deficient embryos at the indicated times post-conception. Data are the mean ± standard error; 22–55 embryos were analysed per timepoint (KOs: n = 8 (E12.5), 12 (E14.5), 8 (E15.5), 11 (E16.5), and 4 (E18.5). (B) Crown-rump length of embryos determined by histomorphometry. Data are mean ± standard error, n = 3–9 per data point. *p<0.05, **p<0.01, ***p<0.001.
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pgen-1001170-g002: Late gestational growth defect of Asciz-deficient embryos.(A) Embryo weights of WT, heterozygotes and Asciz-deficient embryos at the indicated times post-conception. Data are the mean ± standard error; 22–55 embryos were analysed per timepoint (KOs: n = 8 (E12.5), 12 (E14.5), 8 (E15.5), 11 (E16.5), and 4 (E18.5). (B) Crown-rump length of embryos determined by histomorphometry. Data are mean ± standard error, n = 3–9 per data point. *p<0.05, **p<0.01, ***p<0.001.

Mentions: The absence of homozygous Asciz−/− mice at weaning prompted us to investigate the development of ASCIZ-deficient embryos in more detail. Asciz−/− embryos were recovered at near-Mendelian ratios at all time points analysed (Table 1). Based on peripheral circulation scored during uterine dissections, Asciz−/− embryos appeared to lose viability around embryonic day 16.5 post conception (E16.5) (Table 1), at which point they were considerably growth-retarded compared to littermates (Figure 2A, 2B). Embryonic lethality due to DNA damage response gene deletions can often be suppressed by p53 deletion [6]. To test if p53 status affects the essential requirement for Asciz, we intercrossed compound Asciz+/−/p53+/− heterozygous mice. However, we could again not detect any viable Asciz−/− mice amongst >300 genotyped offspring at weaning (Table 2). Altogether, these data indicate that absence of Asciz leads to progressively impaired development during late gestation and becomes absolutely incompatible with life a few days before term.


Dual functions of ASCIZ in the DNA base damage response and pulmonary organogenesis.

Jurado S, Smyth I, van Denderen B, Tenis N, Hammet A, Hewitt K, Ng JL, McNees CJ, Kozlov SV, Oka H, Kobayashi M, Conlan LA, Cole TJ, Yamamoto K, Taniguchi Y, Takeda S, Lavin MF, Heierhorst J - PLoS Genet. (2010)

Late gestational growth defect of Asciz-deficient embryos.(A) Embryo weights of WT, heterozygotes and Asciz-deficient embryos at the indicated times post-conception. Data are the mean ± standard error; 22–55 embryos were analysed per timepoint (KOs: n = 8 (E12.5), 12 (E14.5), 8 (E15.5), 11 (E16.5), and 4 (E18.5). (B) Crown-rump length of embryos determined by histomorphometry. Data are mean ± standard error, n = 3–9 per data point. *p<0.05, **p<0.01, ***p<0.001.
© Copyright Policy
Related In: Results  -  Collection

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getmorefigures.php?uid=PMC2958817&req=5

pgen-1001170-g002: Late gestational growth defect of Asciz-deficient embryos.(A) Embryo weights of WT, heterozygotes and Asciz-deficient embryos at the indicated times post-conception. Data are the mean ± standard error; 22–55 embryos were analysed per timepoint (KOs: n = 8 (E12.5), 12 (E14.5), 8 (E15.5), 11 (E16.5), and 4 (E18.5). (B) Crown-rump length of embryos determined by histomorphometry. Data are mean ± standard error, n = 3–9 per data point. *p<0.05, **p<0.01, ***p<0.001.
Mentions: The absence of homozygous Asciz−/− mice at weaning prompted us to investigate the development of ASCIZ-deficient embryos in more detail. Asciz−/− embryos were recovered at near-Mendelian ratios at all time points analysed (Table 1). Based on peripheral circulation scored during uterine dissections, Asciz−/− embryos appeared to lose viability around embryonic day 16.5 post conception (E16.5) (Table 1), at which point they were considerably growth-retarded compared to littermates (Figure 2A, 2B). Embryonic lethality due to DNA damage response gene deletions can often be suppressed by p53 deletion [6]. To test if p53 status affects the essential requirement for Asciz, we intercrossed compound Asciz+/−/p53+/− heterozygous mice. However, we could again not detect any viable Asciz−/− mice amongst >300 genotyped offspring at weaning (Table 2). Altogether, these data indicate that absence of Asciz leads to progressively impaired development during late gestation and becomes absolutely incompatible with life a few days before term.

Bottom Line: Unexpectedly, Asciz-deficient embryos also exhibit severe respiratory tract defects with complete pulmonary agenesis and severe tracheal atresia.Comparison of phenotypes suggests that ASCIZ functions between Wnt2-2b/ß-catenin and FGF10/FGF-receptor 2b signaling pathways in the mesodermal/endodermal crosstalk regulating early respiratory development.We also find that ASCIZ can activate expression of reporter genes via its SQ/TQ-cluster domain in vitro, suggesting that it may exert its developmental functions as a transcription factor.

View Article: PubMed Central - PubMed

Affiliation: St. Vincent's Institute of Medical Research, Fitzroy, Australia.

ABSTRACT
Zn²(+)-finger proteins comprise one of the largest protein superfamilies with diverse biological functions. The ATM substrate Chk2-interacting Zn²(+)-finger protein (ASCIZ; also known as ATMIN and ZNF822) was originally linked to functions in the DNA base damage response and has also been proposed to be an essential cofactor of the ATM kinase. Here we show that absence of ASCIZ leads to p53-independent late-embryonic lethality in mice. Asciz-deficient primary fibroblasts exhibit increased sensitivity to DNA base damaging agents MMS and H2O2, but Asciz deletion knock-down does not affect ATM levels and activation in mouse, chicken, or human cells. Unexpectedly, Asciz-deficient embryos also exhibit severe respiratory tract defects with complete pulmonary agenesis and severe tracheal atresia. Nkx2.1-expressing respiratory precursors are still specified in the absence of ASCIZ, but fail to segregate properly within the ventral foregut, and as a consequence lung buds never form and separation of the trachea from the oesophagus stalls early. Comparison of phenotypes suggests that ASCIZ functions between Wnt2-2b/ß-catenin and FGF10/FGF-receptor 2b signaling pathways in the mesodermal/endodermal crosstalk regulating early respiratory development. We also find that ASCIZ can activate expression of reporter genes via its SQ/TQ-cluster domain in vitro, suggesting that it may exert its developmental functions as a transcription factor. Altogether, the data indicate that, in addition to its role in the DNA base damage response, ASCIZ has separate developmental functions as an essential regulator of respiratory organogenesis.

Show MeSH
Related in: MedlinePlus