Plac1 (placenta-specific 1) is essential for normal placental and embryonic development.
Plac1 is a recently identified, X-linked gene whose expression is restricted primarily to cells of the trophoblast lineage. It localizes to a chromosomal locus previously implicated in placental growth. We therefore sought to determine if Plac1 is necessary for placental and embryonic development by examining a mutant mouse model. Plac1 ablation resulted in placentomegaly and mild intrauterine growth retardation (IUGR). At E16.5, knockout (KO) and heterozygous (Het) placentae of the Plac1-null allele inherited from the mother (X(m-) X) weighed approximately 100% more than wildtype (WT) placentae, whereas the corresponding embryos weighed 7-12% less. Histologically, Plac1 mutants exhibited an expanded spongiotrophoblast layer that invaded the labyrinth. By contrast, Het placentae that inherited the null allele from the father (XX(p-) ) exhibited normal growth and were histologically indistinguishable from WT placentae, consistent with paternal imprinting of Plac1. When examined across gestation, WT and X(m-) X placental weights peaked at E16.5 and decreased slightly thereafter. KO placentae (X(m-) X(p-) and X(m-) Y), however, continued to increase in weight after E16.5, consistent with a functional role for the paternal Plac1 allele. Subsequent analysis confirmed that the paternal allele partially escapes complete X-inactivation and thus contributes to placental growth regulation. Additionally, although male Plac1 KO mice can survive, they exhibit decreased viability as a consequence of events occurring late in gestation or shortly after birth. Thus, Plac1 is a paternally imprinted, X-linked gene essential for normal placental and embryonic development.
Department of Pediatrics, University of South Florida Morsani College of Medicine, Tampa, FL, USA.
Suzanne M
SM
Jackman
Xiaoyuan
X
Kong
Michael E
ME
Fant
D000483:Alleles; D000818:Animals; D033481:Chromosomes, Mammalian / Q000235:genetics / Q000378:metabolism; D004622:Embryo, Mammalian / Q000166:cytology / Q000378:metabolism*; D047108:Embryonic Development / Q000502:physiology*; D005260:Female; D050172:Genes, X-Linked; D018392:Genomic Imprinting / Q000502:physiology*; D006579:Heterozygote; D008297:Male; D051379:Mice; D018345:Mice, Knockout; D010920:Placenta / Q000166:cytology / Q000196:embryology*; D011247:Pregnancy / Q000502:physiology*; D011257:Pregnancy Proteins / Q000235:genetics / Q000378:metabolism*; D014960:X Chromosome / Q000235:genetics / Q000378:metabolism
D011257:Pregnancy Proteins