Placental expression of matriptase restores survival in PAR-2 and matriptase double-deficient embryos.

<p>(<b>A</b>). Schematic depiction of the strategy used to assess contribution of placental matriptase to the survival of the <i>F2rl1^−/−;St14^−/−</i> embryos. <i>Meox2-Cre</i> allele that drives the expression of Cre recombinase to the embryonic but not placental tissues was introduced into the mice carrying one null and one conditional allele of matriptase gene (<i>St14^−/fl</i>). The resulting mice retain expression of matriptase in the placenta but not in any of the embryonic tissues. Both the embryo and the placenta are also PAR-2-deficient (<i>F2rl1^−/−</i>). (<b>B</b>). Western blot analysis of matriptase expression in the embryo (top) and the placenta (bottom) of the E13.5 <i>Meox2-Cre;St14^−/fl</i> (lanes 1–3), and their <i>St14^+/fl</i> (lanes 4–6) and <i>St14^−/−</i> (lane 7) littermate control animals. Both the embryos and the placentas of the control mice showed detectable levels of matriptase protein (arrowheads on the right), whereas only placental tissue retained matriptase expression in the <i>Meox2-Cre;St14^−/fl</i> embryos. No matriptase expression was detected in either embryos or placentas of animals carrying two knockout alleles of matriptase (<i>St14^−/−</i>). GAPDH signal is shown to indicate equal loading. Positions of molecular weight markers (kDa) are shown on left. (<b>C</b>). Allele distribution of the <i>F2rl1</i> gene among newborn matriptase-deficient offspring from interbred <i>F2rl1^+/−;St14^+/−</i>×<i>F2rl1</i>^+/−;<i>St14^+/−</i> (<i>St14^−/−</i>, left panels) or <i>Meox2-Cre;F2rl1^+/−;St14^+/−</i>×<i>F2rl1^+/−;St14^−/fl</i> (<i>Meox2-Cre;St14^−/fl</i>, right panels) breeder mice. Placental expression of matriptase restores embryonic survival of the PAR-2 and matriptase double-deficient mice. (<b>D, E</b>). Macroscopic appearance of the head of control (<b>D</b>) or <i>Meox2-Cre;F2rl1^−/−;St14^−/fl</i> (<b>E</b>) mice at birth. The <i>Meox2-Cre;F2rl1^−/−;St14^−/fl</i> newborns reproduce phenotypes of mice with complete matriptase deficiency, including the lack of whiskers. (<b>F</b>). Western blot analysis of matriptase expression in two <i>Meox2-Cre;F2rl1^−/−;St14^−/fl</i> (lanes 1–2) and two littermate control (lanes 3–4) newborn mice. No residual expression of matriptase protein (arrowhead on the right) was detected in the <i>Meox2-Cre;F2rl1^−/−;St14^−/fl</i> mice. Positions of molecular weight markers (kDa) are shown on left.