MIRI PI PhD Mary Wallingford, who will attend at the 22nd International Vascular Biology Meeting on October 13-17, 2022 in Oakland, California, had three abstracts accepted for presentation.
“Advancing Knowledge on the Effects and Pathogenesis of Hereditary Hemorrhagic Telangiectasia in Pregnancy,” Mathew M, Mei A, Mann M, Jayarman N, Joe A, O’Tierney-Ginn P, Alvarez F, Bhave SA, Hirschi K, Kapur N, Good ME, Wallingford MC. Oral Presentation: Hereditary hemorrhagic telangiectasia (HHT) is a genetic disease distinguished by malformed vasculature. During pregnancy, undiagnosed HHT confers an increased risk for maternal mortality from vascular complications, although the underlying mechanism remains unknown. This study aims to evaluate placental expression of HHT-associated genes including ENG, ALK1, SMAD4, BMP9, and to explore placental vascular health and pathogenesis in HHT. Immunofluorescence, proteomics, and in silico approaches were used to test the hypothesis that HHT gene expression in placenta is required for vascular integrity and gap junction formation, specifically connexin (CX43) expression. Morphology of placental vessels was evaluated in clinical biopsies and Eng and Alk1 knock-out (KO) placenta. Our results confirmed that HHT proteins were detected throughout development in the placenta. Furthermore, endothelial disruption and cellular disorganization were observed in HHT-affected human placental vessels. Alk1 and Eng KO mice resulted in embryonic lethality as expected at embryonic day (E)11.5, and placental health was evaluated at earlier stages and demonstrated hemorrhage, dilated vessels, and structural impairments. Additionally, Eng KO placenta showed loss of CX43 expression. In conclusion, placental vascular abnormalities in preclinical models and in HHT-affected clinical tissues suggest a role for HHT pathways in the regulation placental vascular development. Finally, loss of CX43 in Eng KO mice supports our hypothesis that gap junction dysregulation may contribute to the pathological mechanism of HHT.
“Interaction of Inorganic Phosphate and Unfolded Protein Response (UPR) in Placenta,” Branco A, Joe A, Hinderer EW, Jayaraman N, Kashpur O, Blaser MC, Higashi H, Kuraoka S, Mahmoud T, O’Tierney-Ginn T, Singh SA, Aikawa E, Wallingford MC. Poster Presentation: Inorganic phosphate (Pi) performs critical functions during embryonic development, but chronic exposure to Pi is detrimental to vascular health. In this study we evaluated the role of Pi in placental vascular health at the molecular level. Our previous work identified Slc20a2 as a sodium-dependent placental Pi transporter that protects against ectopic placental calcification. In this study, we used a global, unbiased proteomics approach to compare Slc20a2 WT and KO mouse placenta collected before (E13.5) and after (E17.5) calcification onset. After filtering and normalization, a total of 3,050 unique proteins were identified. Proteins with altered abundance patterns were analyzed with STRINGdb, and revealed a cluster of endoplasmic reticulum, Golgi and mitochondria proteins. Clinically, expression of placental Slc20a2 is decreased in early preeclampsia (PE) while the homeostatic endoplasmic stress unfolded protein response (UPRER) is dysregulated. We used molecular approaches to the hypothesis that Slc20a2 protects the placenta from ectopic calcification by maintaining homeostatic Pi levels in balance with UPRER. Western blotting and immunofluorescence revealed that Slc20a2 loss significantly increases eukaryotic translation initiation factor 2A (eIF2α) and its downstream target protein disulfide isomerase (PDI). We now propose that Slc20a2 protects the placenta from ectopic calcification by maintaining homeostatic Pi levels in balance with UPRER. Future work aims to determine whether this molecular relationship is conserved in preeclamptic placenta tissue and will evaluate attenuation of Slc20a2 expression and eIF2α-mediated PDI activation in trophoblasts.
“Mouse Placenta Proteome Dynamics Support the Critical Significance of Timing in Placenta Research,” Kashpur O, Mei A, Kuraoka S, Higashi H, Aikawa E, Singh SA, Wallingford MC. Poster Presentation: The placenta is critical for maternal and fetal health. Abnormal placentation is associated with adverse clinical outcomes, e.g. preeclampsia, fetal growth restriction, preterm birth. This study aimed to define developmental stage-specific placental protein networks. Allantois, chorion and placenta were collected at 12h intervals between E8.5-E12.5 and 24h intervals between E12.5-E17.5 (N=45). Proteomes differed significantly with gestational age, permitting the detailed delineation of temporal abundance patterns. Functional enrichment analyses identified processes coinciding with: differentiation of E8.5 progenitors, chorioallantoic fusion, phases of placental development, and placental maturation/aging. Cellular compartment mapping revealed a stark contrast between allantois and chorion. Focal adhesions, cell-substrate interactions, and collagen were enriched in allantois. Metabolic processes and transmembrane transport were enriched in chorion. In placenta, 1401 proteins were differentially abundant between early (E8.5-E10.5) and late (E11.0-E13.5) developmental phases (q<0.01). Vascular processes and regulation of gene expression were enriched in early development. Transport, adhesion, and trophoblast genes were enriched in later stages. The transition to placental aging was marked by 1174 differentially abundant proteins (q<0.01) involved in metabolic processes, cell-matrix adhesion, and death receptor signaling. Further studies are needed to determine which of these novel stage-specific molecular networks are critical for placental health. Study supported by: NIH R00HD090198 and AHA 19CDA34660038 to MCW, NIH R01HL136431 and R01HL147095 to EA, and the Susan Saltonstall and Herbert J. Levine foundations.
Read more about Dr. Wallingford’s research here.