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Keratin 8 protection of placental barrier function.

Jaquemar D, Kupriyanov S, Wankell M, Avis J, Benirschke K, Baribault H, Oshima RG - J. Cell Biol. (2003)

Bottom Line: The ConA-induced failure of the trophoblast giant cell barrier results in hematoma formation between the trophoblast giant cell layer and the embryonic yolk sac in a phenocopy of dying K8-deficient concepti in a sensitive genetic background.We conclude the lethality of K8-/- embryos is due to a TNF-sensitive failure of trophoblast giant cell barrier function.The keratin-dependent protection of trophoblast giant cells from a maternal TNF-dependent apoptotic challenge may be a key function of simple epithelial keratins.

View Article: PubMed Central - PubMed

Affiliation: The Burnham Institute, La Jolla, CA 92037, USA.

ABSTRACT
The intermediate filament protein keratin 8 (K8) is critical for the development of most mouse embryos beyond midgestation. We find that 68% of K8-/- embryos, in a sensitive genetic background, are rescued from placental bleeding and subsequent death by cellular complementation with wild-type tetraploid extraembryonic cells. This indicates that the primary defect responsible for K8-/- lethality is trophoblast giant cell layer failure. Furthermore, the genetic absence of maternal but not paternal TNF doubles the number of viable K8-/- embryos. Finally, we show that K8-/- concepti are more sensitive to a TNF-dependent epithelial apoptosis induced by the administration of concanavalin A (ConA) to pregnant mothers. The ConA-induced failure of the trophoblast giant cell barrier results in hematoma formation between the trophoblast giant cell layer and the embryonic yolk sac in a phenocopy of dying K8-deficient concepti in a sensitive genetic background. We conclude the lethality of K8-/- embryos is due to a TNF-sensitive failure of trophoblast giant cell barrier function. The keratin-dependent protection of trophoblast giant cells from a maternal TNF-dependent apoptotic challenge may be a key function of simple epithelial keratins.

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More K8−/− mice are recovered in the absence of maternal TNFR2. The same strategy shown in Fig. 2 was used for the K8 × TNFR2 crosses except that cross C2 was not performed. (A) The number of mice obtained from the K8 × TNFR2 cross as determined by tail DNA PCR. (B) The observed number of K8 wild-type, K8 heterozygote, and K8 knockout mice from crosses C1 are compared with the percentage of recovery from cross C3 as standard using the Chi squared analysis. (C) Graphic representation of the recovery of K8 genotypes to that expected for Mendelian inheritance.
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fig4: More K8−/− mice are recovered in the absence of maternal TNFR2. The same strategy shown in Fig. 2 was used for the K8 × TNFR2 crosses except that cross C2 was not performed. (A) The number of mice obtained from the K8 × TNFR2 cross as determined by tail DNA PCR. (B) The observed number of K8 wild-type, K8 heterozygote, and K8 knockout mice from crosses C1 are compared with the percentage of recovery from cross C3 as standard using the Chi squared analysis. (C) Graphic representation of the recovery of K8 genotypes to that expected for Mendelian inheritance.

Mentions: We also tested the influence of TNFR2 deficiency on K8−/− viability. K8+/−(FVB/N) mice were bred with TNFR2−/− (B6;129), and progeny were backcrossed with TNFR2−/−(B6;129) to generate K8+/−;TNFR2−/− males and either K8+/−;TNFR2−/− or K8+/−;TNFR2+/− mothers (analogous to C1 and C3 crosses of Fig. 2 A). The absence of TNFR2 in mothers resulted in a more than fourfold increase in the frequency of K8−/− progeny (Fig. 4 A). The difference between the recoveries of K8−/− progeny was statistically significant (Fig. 4 B). However, TNFR2 deficiency also failed to completely rescue K8−/− lethality (Fig. 4 C). TNFR2-deficient embryos were found as frequently as TNFR2 heterozygotes. Thus, both embryonic TNFR2 and TNF are dispensable for embryonic development. In the presence of maternal TNFR2, K8−/− embryos with an absence of TNFR2 were not recovered more frequently than K8−/− embryos with TNFR2 (Fig. 3 A, C3). Thus, the possible modulation of TNFR2 signaling by K8/K18 is not sufficient to ensure embryo survival. The recovery of K8+/+ and K8+/− animals was statistically not distinguishable from the expected number based on Mendelian inheritance (Fig. 3 C). The lower recovery of K8−/− embryos from the C3 cross with TNFR2− compared with the analogous C3 cross with TNF− may be due to differences in the contributions of the B6 and 129 genetic backgrounds in the TNF−/− and TNFR2−/− mouse strains. These results indicate that maternal TNFR2 contributes to the death of K8−/− embryos but provides no support for a role for embryonic TNFR2 in the death of K8−/− embryos.


Keratin 8 protection of placental barrier function.

Jaquemar D, Kupriyanov S, Wankell M, Avis J, Benirschke K, Baribault H, Oshima RG - J. Cell Biol. (2003)

More K8−/− mice are recovered in the absence of maternal TNFR2. The same strategy shown in Fig. 2 was used for the K8 × TNFR2 crosses except that cross C2 was not performed. (A) The number of mice obtained from the K8 × TNFR2 cross as determined by tail DNA PCR. (B) The observed number of K8 wild-type, K8 heterozygote, and K8 knockout mice from crosses C1 are compared with the percentage of recovery from cross C3 as standard using the Chi squared analysis. (C) Graphic representation of the recovery of K8 genotypes to that expected for Mendelian inheritance.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2199358&req=5

fig4: More K8−/− mice are recovered in the absence of maternal TNFR2. The same strategy shown in Fig. 2 was used for the K8 × TNFR2 crosses except that cross C2 was not performed. (A) The number of mice obtained from the K8 × TNFR2 cross as determined by tail DNA PCR. (B) The observed number of K8 wild-type, K8 heterozygote, and K8 knockout mice from crosses C1 are compared with the percentage of recovery from cross C3 as standard using the Chi squared analysis. (C) Graphic representation of the recovery of K8 genotypes to that expected for Mendelian inheritance.
Mentions: We also tested the influence of TNFR2 deficiency on K8−/− viability. K8+/−(FVB/N) mice were bred with TNFR2−/− (B6;129), and progeny were backcrossed with TNFR2−/−(B6;129) to generate K8+/−;TNFR2−/− males and either K8+/−;TNFR2−/− or K8+/−;TNFR2+/− mothers (analogous to C1 and C3 crosses of Fig. 2 A). The absence of TNFR2 in mothers resulted in a more than fourfold increase in the frequency of K8−/− progeny (Fig. 4 A). The difference between the recoveries of K8−/− progeny was statistically significant (Fig. 4 B). However, TNFR2 deficiency also failed to completely rescue K8−/− lethality (Fig. 4 C). TNFR2-deficient embryos were found as frequently as TNFR2 heterozygotes. Thus, both embryonic TNFR2 and TNF are dispensable for embryonic development. In the presence of maternal TNFR2, K8−/− embryos with an absence of TNFR2 were not recovered more frequently than K8−/− embryos with TNFR2 (Fig. 3 A, C3). Thus, the possible modulation of TNFR2 signaling by K8/K18 is not sufficient to ensure embryo survival. The recovery of K8+/+ and K8+/− animals was statistically not distinguishable from the expected number based on Mendelian inheritance (Fig. 3 C). The lower recovery of K8−/− embryos from the C3 cross with TNFR2− compared with the analogous C3 cross with TNF− may be due to differences in the contributions of the B6 and 129 genetic backgrounds in the TNF−/− and TNFR2−/− mouse strains. These results indicate that maternal TNFR2 contributes to the death of K8−/− embryos but provides no support for a role for embryonic TNFR2 in the death of K8−/− embryos.

Bottom Line: The ConA-induced failure of the trophoblast giant cell barrier results in hematoma formation between the trophoblast giant cell layer and the embryonic yolk sac in a phenocopy of dying K8-deficient concepti in a sensitive genetic background.We conclude the lethality of K8-/- embryos is due to a TNF-sensitive failure of trophoblast giant cell barrier function.The keratin-dependent protection of trophoblast giant cells from a maternal TNF-dependent apoptotic challenge may be a key function of simple epithelial keratins.

View Article: PubMed Central - PubMed

Affiliation: The Burnham Institute, La Jolla, CA 92037, USA.

ABSTRACT
The intermediate filament protein keratin 8 (K8) is critical for the development of most mouse embryos beyond midgestation. We find that 68% of K8-/- embryos, in a sensitive genetic background, are rescued from placental bleeding and subsequent death by cellular complementation with wild-type tetraploid extraembryonic cells. This indicates that the primary defect responsible for K8-/- lethality is trophoblast giant cell layer failure. Furthermore, the genetic absence of maternal but not paternal TNF doubles the number of viable K8-/- embryos. Finally, we show that K8-/- concepti are more sensitive to a TNF-dependent epithelial apoptosis induced by the administration of concanavalin A (ConA) to pregnant mothers. The ConA-induced failure of the trophoblast giant cell barrier results in hematoma formation between the trophoblast giant cell layer and the embryonic yolk sac in a phenocopy of dying K8-deficient concepti in a sensitive genetic background. We conclude the lethality of K8-/- embryos is due to a TNF-sensitive failure of trophoblast giant cell barrier function. The keratin-dependent protection of trophoblast giant cells from a maternal TNF-dependent apoptotic challenge may be a key function of simple epithelial keratins.

Show MeSH
Related in: MedlinePlus