title: The double life of MULE in preeclamptic and IUGR placentae.
abstract: The E3 ubiquitin ligase MULE (Mcl-1 Ubiquitin Ligases E3) targets myeloid cell leukemia factor 1 (Mcl-1) and tumor suppressor p53 for proteasomal degradation. Although Mcl-1 and p53 have been implicated in trophoblast cell death in preeclampsia (PE) and intrauterine growth restriction (IUGR), the mechanisms regulating their expression in the human placenta remains elusive. Herein, we investigated MULE's involvement in regulating Mcl-1 and p53 degradation during normal and abnormal (PE, IUGR) placental development. MULE expression peaked at 5-7 weeks of gestation, when oxygen tension is low and inversely correlated with that of Mcl-1 and p53. MULE efficiently bound to Mcl-1 and p53 and regulated their ubiquitination during placental development. Exposure of first trimester villous explants to 3% O(2) resulted in elevated MULE expression compared with 20% O(2). Low-oxygen-induced MULE expression in JEG3 choriocarcinoma cells was abolished by hypoxia-inducible factor (HIF)-1α siRNA. MULE was overexpressed in both PE and IUGR placentae. In PE, MULE preferentially targeted p53 for degradation, allowing accumulation of pro-apoptotic Mcl-1 isoforms. In IUGR, however, MULE targeted pro-survival Mcl-1, allowing p53 to accumulate and exert its apoptotic function. These data demonstrate that oxygen regulates Mcl-1 and p53 stability during placentation via HIF-1-controlled MULE expression. The different preferential targets of MULE in PE and IUGR placentae classify early-onset PE and IUGR as distinct molecular pathologies.
authors.affiliation: Samuel Lunenfeld Research Institute, Mount Sinai Hospital, Toronto, Ontario, Canada.
authors.forename: A
authors.initials: A
authors.lastname: Rolfo
authors.forename: J
authors.initials: J
authors.lastname: Garcia
authors.forename: T
authors.initials: T
authors.lastname: Todros
authors.forename: M
authors.initials: M
authors.lastname: Post
authors.forename: I
authors.initials: I
authors.lastname: Caniggia
mesh_terms: D045744:Cell Line, Tumor; D005260:Female; D005317:Fetal Growth Retardation / Q000378:metabolism* / Q000473:pathology; D005865:Gestational Age; D057809:HEK293 Cells; D006801:Humans; D051795:Hypoxia-Inducible Factor 1, alpha Subunit / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D064549:Myeloid Cell Leukemia Sequence 1 Protein; D010100:Oxygen / Q000378:metabolism; D010920:Placenta / Q000378:metabolism*; D010929:Placentation; D011225:Pre-Eclampsia / Q000378:metabolism* / Q000473:pathology; D011247:Pregnancy; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000235:genetics / Q000378:metabolism; D034622:RNA Interference; D034741:RNA, Small Interfering / Q000378:metabolism; D016159:Tumor Suppressor Protein p53 / Q000235:genetics / Q000378:metabolism; D025521:Tumor Suppressor Proteins; D044767:Ubiquitin-Protein Ligases / Q000378:metabolism*; D054875:Ubiquitination
chemical_list: D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D064549:Myeloid Cell Leukemia Sequence 1 Protein; D019253:Proto-Oncogene Proteins c-bcl-2; D034741:RNA, Small Interfering; D016159:Tumor Suppressor Protein p53; D025521:Tumor Suppressor Proteins; C502830:HUWE1 protein, human; D044767:Ubiquitin-Protein Ligases; D010100:Oxygen