title: Biparental expression of ESX1L gene in placentas from normal and intrauterine growth-restricted pregnancies.
abstract: Equivalent levels of X-linked gene products between males and females are reached by means of X chromosome inactivation (XCI). In the human and murine embryonic tissues, both the paternally and maternally derived X chromosomes (X(P) and X(M)) may be inactivated. In murine extra-embryonic tissues, X(P) is imprinted and always silenced; humans, unlike mice, can inactivate the X(M) in extra-embryonic lineages without an adverse outcome. This difference is probably due to the presence of imprinted placental genes on the murine X chromosome, but not on the human homologue, essential for placental development and function. An example is the paternally imprinted Esx1 gene; mice with a null maternally derived Esx1 allele show intrauterine growth restriction (IUGR) because of placental insufficiency. We investigated the imprinting status of the human orthologous Esx1 gene (ESX1L) in placental samples of four normal full-term and 13 IUGR female fetuses, in which we determined the XCI pattern. Our findings demonstrated that IUGR as well as normal placentas display XCI heterogeneity, thus indicating that the IUGR phenotype is not correlated with a preferential pattern of XCI in placentas. Moreover, ESX1L is equally expressed in IUGR and normal placentas, and shows the same methylation pattern in the presence of both random and skewed XCI. These findings provide evidence that ESX1L is not imprinted in human third-trimester placentas and there is no parent-of-origin effect of chromosome X associated with placental insufficiency.
authors.affiliation: Dipartimento di Medicina, Chirurgia ed Odontoiatria, Università di Milano, Milano, Italy.
authors.forename: Francesca R
authors.initials: FR
authors.lastname: Grati
authors.forename: Silvia M
authors.initials: SM
authors.lastname: Sirchia
authors.forename: Barbara
authors.initials: B
authors.lastname: Gentilin
authors.forename: Franca
authors.initials: F
authors.lastname: Rossella
authors.forename: Lisetta
authors.initials: L
authors.lastname: Ramoscelli
authors.forename: Patrizio
authors.initials: P
authors.lastname: Antonazzo
authors.forename: Ugo
authors.initials: U
authors.lastname: Cavallari
authors.forename: Gaetano
authors.initials: G
authors.lastname: Bulfamante
authors.forename: Irene
authors.initials: I
authors.lastname: Cetin
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Simoni
authors.forename: Monica
authors.initials: M
authors.lastname: Miozzo
mesh_terms: D001483:Base Sequence; D019175:DNA Methylation; D017931:DNA Primers; D004303:Dosage Compensation, Genetic; D005260:Female; D005317:Fetal Growth Retardation / Q000378:metabolism*; D018392:Genomic Imprinting; D018398:Homeodomain Proteins / Q000235:genetics*; D006801:Humans; D008297:Male; D010920:Placenta / Q000378:metabolism*; D011247:Pregnancy
chemical_list: D017931:DNA Primers; C432969:ESX1 protein, human; D018398:Homeodomain Proteins