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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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Breeding strategy to test the influence of TNF on K8−/− survival. Two rounds of matings (G1 and G2) were performed to obtain the mouse genotypes needed for the experimental matings (G3) that produced offspring of experimental matings C1, C2, and C3. All parents were K8+/−.
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fig2: Breeding strategy to test the influence of TNF on K8−/− survival. Two rounds of matings (G1 and G2) were performed to obtain the mouse genotypes needed for the experimental matings (G3) that produced offspring of experimental matings C1, C2, and C3. All parents were K8+/−.

Mentions: Some K8−/− epithelial cell lines are 100-fold more sensitive to TNF-induced apoptosis (Caulin et al., 2000). To test genetically whether TNF may contribute to the death of K8−/− embryos, we combined the K8 deficiency (FVB/N) with TNF deficiency (C57Bl/6;129). The FVB/N genetic background was chosen for the K8−/− mice to efficiently obtain adequate numbers of progeny for statistical analysis. Interbreeding of the two targeted alleles resulted in mixed background (FVB/N;B6;129) K8+/− parents with either TNF+/− or TNF−/− (Fig. 2, G3). The recovery of K8−/− progeny from three different crosses was measured. If TNF and the maternal immune system participated in the death of K8−/− embryos, a maternal dependence on TNF was expected. Approximately twice as many K8−/− progeny were recovered when the mother was TNF−/− (C1 and C2) than when the mother was TNF+/− (Fig. 3, A and B). The difference in K8−/− recovery from the C1 cross was significantly different from the reciprocal C3 cross in which the father, rather than the mother, was TNF+/− (Fig. 3 B). TNF deficiency of both the mother and father did not yield greater recovery of K8−/− progeny than when only the mother was deficient. Combining the results of both crosses in which the mothers were TNF−/− (C1 and C2) further reinforced the conclusion. However, a full recovery of K8−/− mice was not obtained. The recovery of K8−/− mice increased from ∼25% to >50% of the number expected for Mendelian inheritance (Fig. 2 C). The recovery of K8+/+ and K8+/− mice did not differ significantly from the expected number. Survival of TNF+/− and TNF−/− progeny in the C2 and C3 crosses were not statistically different (46 TNF+/− versus 51 TNF−/−). Thus, TNF deficiency of the embryo does not influence survival. These data indicate that maternally expressed TNF is deleterious to the survival 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)

Breeding strategy to test the influence of TNF on K8−/− survival. Two rounds of matings (G1 and G2) were performed to obtain the mouse genotypes needed for the experimental matings (G3) that produced offspring of experimental matings C1, C2, and C3. All parents were K8+/−.
© Copyright Policy
Related In: Results  -  Collection

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

fig2: Breeding strategy to test the influence of TNF on K8−/− survival. Two rounds of matings (G1 and G2) were performed to obtain the mouse genotypes needed for the experimental matings (G3) that produced offspring of experimental matings C1, C2, and C3. All parents were K8+/−.
Mentions: Some K8−/− epithelial cell lines are 100-fold more sensitive to TNF-induced apoptosis (Caulin et al., 2000). To test genetically whether TNF may contribute to the death of K8−/− embryos, we combined the K8 deficiency (FVB/N) with TNF deficiency (C57Bl/6;129). The FVB/N genetic background was chosen for the K8−/− mice to efficiently obtain adequate numbers of progeny for statistical analysis. Interbreeding of the two targeted alleles resulted in mixed background (FVB/N;B6;129) K8+/− parents with either TNF+/− or TNF−/− (Fig. 2, G3). The recovery of K8−/− progeny from three different crosses was measured. If TNF and the maternal immune system participated in the death of K8−/− embryos, a maternal dependence on TNF was expected. Approximately twice as many K8−/− progeny were recovered when the mother was TNF−/− (C1 and C2) than when the mother was TNF+/− (Fig. 3, A and B). The difference in K8−/− recovery from the C1 cross was significantly different from the reciprocal C3 cross in which the father, rather than the mother, was TNF+/− (Fig. 3 B). TNF deficiency of both the mother and father did not yield greater recovery of K8−/− progeny than when only the mother was deficient. Combining the results of both crosses in which the mothers were TNF−/− (C1 and C2) further reinforced the conclusion. However, a full recovery of K8−/− mice was not obtained. The recovery of K8−/− mice increased from ∼25% to >50% of the number expected for Mendelian inheritance (Fig. 2 C). The recovery of K8+/+ and K8+/− mice did not differ significantly from the expected number. Survival of TNF+/− and TNF−/− progeny in the C2 and C3 crosses were not statistically different (46 TNF+/− versus 51 TNF−/−). Thus, TNF deficiency of the embryo does not influence survival. These data indicate that maternally expressed TNF is deleterious to the survival 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