Browsing by Author "Souzeau, Emmanuelle"

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    Angiopoietin receptor TEK mutations underlie primary congenital glaucoma with variable expressivity.
    (The Journal of clinical investigation, 2016-07) Souma, Tomokazu; Tompson, Stuart W; Thomson, Benjamin R; Siggs, Owen M; Kizhatil, Krishnakumar; Yamaguchi, Shinji; Feng, Liang; Limviphuvadh, Vachiranee; Whisenhunt, Kristina N; Maurer-Stroh, Sebastian; Yanovitch, Tammy L; Kalaydjieva, Luba; Azmanov, Dimitar N; Finzi, Simone; Mauri, Lucia; Javadiyan, Shahrbanou; Souzeau, Emmanuelle; Zhou, Tiger; Hewitt, Alex W; Kloss, Bethany; Burdon, Kathryn P; Mackey, David A; Allen, Keri F; Ruddle, Jonathan B; Lim, Sing-Hui; Rozen, Steve; Tran-Viet, Khanh-Nhat; Liu, Xiaorong; John, Simon; Wiggs, Janey L; Pasutto, Francesca; Craig, Jamie E; Jin, Jing; Quaggin, Susan E; Young, Terri L
    Primary congenital glaucoma (PCG) is a devastating eye disease and an important cause of childhood blindness worldwide. In PCG, defects in the anterior chamber aqueous humor outflow structures of the eye result in elevated intraocular pressure (IOP); however, the genes and molecular mechanisms involved in the etiology of these defects have not been fully characterized. Previously, we observed PCG-like phenotypes in transgenic mice that lack functional angiopoietin-TEK signaling. Herein, we identified rare TEK variants in 10 of 189 unrelated PCG families and demonstrated that each mutation results in haploinsufficiency due to protein loss of function. Multiple cellular mechanisms were responsible for the loss of protein function resulting from individual TEK variants, including an absence of normal protein production, protein aggregate formation, enhanced proteasomal degradation, altered subcellular localization, and reduced responsiveness to ligand stimulation. Further, in mice, hemizygosity for Tek led to the formation of severely hypomorphic Schlemm's canal and trabecular meshwork, as well as elevated IOP, demonstrating that anterior chamber vascular development is sensitive to Tek gene dosage and the resulting decrease in angiopoietin-TEK signaling. Collectively, these results identify TEK mutations in patients with PCG that likely underlie disease and are transmitted in an autosomal dominant pattern with variable expressivity.
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    Angiopoietin-1 is required for Schlemm's canal development in mice and humans.
    (The Journal of clinical investigation, 2017-12) Thomson, Benjamin R; Souma, Tomokazu; Tompson, Stuart W; Onay, Tuncer; Kizhatil, Krishnakumar; Siggs, Owen M; Feng, Liang; Whisenhunt, Kristina N; Yanovitch, Tammy L; Kalaydjieva, Luba; Azmanov, Dimitar N; Finzi, Simone; Tanna, Christine E; Hewitt, Alex W; Mackey, David A; Bradfield, Yasmin S; Souzeau, Emmanuelle; Javadiyan, Shari; Wiggs, Janey L; Pasutto, Francesca; Liu, Xiaorong; John, Simon Wm; Craig, Jamie E; Jin, Jing; Young, Terri L; Quaggin, Susan E
    Primary congenital glaucoma (PCG) is a leading cause of blindness in children worldwide and is caused by developmental defects in 2 aqueous humor outflow structures, Schlemm's canal (SC) and the trabecular meshwork. We previously identified loss-of-function mutations in the angiopoietin (ANGPT) receptor TEK in families with PCG and showed that ANGPT/TEK signaling is essential for SC development. Here, we describe roles for the major ANGPT ligands in the development of the aqueous outflow pathway. We determined that ANGPT1 is essential for SC development, and that Angpt1-knockout mice form a severely hypomorphic canal with elevated intraocular pressure. By contrast, ANGPT2 was dispensable, although mice deficient in both Angpt1 and Angpt2 completely lacked SC, indicating that ANGPT2 compensates for the loss of ANGPT1. In addition, we identified 3 human subjects with rare ANGPT1 variants within an international cohort of 284 PCG patients. Loss of function in 2 of the 3 patient alleles was observed by functional analysis of ANGPT1 variants in a combined in silico, in vitro, and in vivo approach, supporting a causative role for ANGPT1 in disease. By linking ANGPT1 with PCG, these results highlight the importance of ANGPT/TEK signaling in glaucoma pathogenesis and identify a candidate target for therapeutic development.
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    SVEP1 as a Genetic Modifier of TEK-Related Primary Congenital Glaucoma.
    (Investigative ophthalmology & visual science, 2020-10) Young, Terri L; Whisenhunt, Kristina N; Jin, Jing; LaMartina, Sarah M; Martin, Sean M; Souma, Tomokazu; Limviphuvadh, Vachiranee; Suri, Fatemeh; Souzeau, Emmanuelle; Zhang, Xue; Dan, Yongwook; Anagnos, Evie; Carmona, Susana; Jody, Nicole M; Stangel, Nickie; Higuchi, Emily C; Huang, Samuel J; Siggs, Owen M; Simões, Maria José; Lawson, Brendan M; Martin, Jacob S; Elahi, Elahe; Narooie-Nejad, Mehrnaz; Motlagh, Behzad Fallahi; Quaggin, Susan E; Potter, Heather D; Silva, Eduardo D; Craig, Jamie E; Egas, Conceição; Maroofian, Reza; Maurer-Stroh, Sebastian; Bradfield, Yasmin S; Tompson, Stuart W
    Purpose:Affecting children by age 3, primary congenital glaucoma (PCG) can cause debilitating vision loss by the developmental impairment of aqueous drainage resulting in high intraocular pressure (IOP), globe enlargement, and optic neuropathy. TEK haploinsufficiency accounts for 5% of PCG in diverse populations, with low penetrance explained by variable dysgenesis of Schlemm's canal (SC) in mice. We report eight families with TEK-related PCG, and provide evidence for SVEP1 as a disease modifier in family 8 with a higher penetrance and severity. Methods:Exome sequencing identified coding/splice site variants with an allele frequency less than 0.0001 (gnomAD). TEK variant effects were assayed in construct-transfected HEK293 cells via detection of autophosphorylated (active) TEK protein. An enucleated eye from an affected member of family 8 was examined via histology. SVEP1 expression in developing outflow tissues was detected by immunofluorescent staining of 7-day mouse anterior segments. SVEP1 stimulation of TEK expression in human umbilical vascular endothelial cells (HUVECs) was measured by TaqMan quantitative PCR. Results:Heterozygous TEK loss-of-function alleles were identified in eight PCG families, with parent-child disease transmission observed in two pedigrees. Family 8 exhibited greater disease penetrance and severity, histology revealed absence of SC in one eye, and SVEP1:p.R997C was identified in four of the five affected individuals. During SC development, SVEP1 is secreted by surrounding tissues. SVEP1:p.R997C abrogates stimulation of TEK expression by HUVECs. Conclusions:We provide further evidence for PCG caused by TEK haploinsufficiency, affirm autosomal dominant inheritance in two pedigrees, and propose SVEP1 as a modifier of TEK expression during SC development, affecting disease penetrance and severity.