Angiopoietin receptor TEK mutations underlie primary congenital glaucoma with variable expressivity
Tomokazu Souma, … , Susan E. Quaggin, Terri L. Young
Tomokazu Souma, … , Susan E. Quaggin, Terri L. Young
Published June 6, 2016
Citation Information: J Clin Invest. 2016;126(7):2575-2587. https://doi.org/10.1172/JCI85830.
View: Text | PDF
Research Article Ophthalmology

Angiopoietin receptor TEK mutations underlie primary congenital glaucoma with variable expressivity

Abstract

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.

Authors

Tomokazu Souma, Stuart W. Tompson, Benjamin R. Thomson, Owen M. Siggs, Krishnakumar Kizhatil, Shinji Yamaguchi, Liang Feng, Vachiranee Limviphuvadh, Kristina N. Whisenhunt, Sebastian Maurer-Stroh, Tammy L. Yanovitch, Luba Kalaydjieva, Dimitar N. Azmanov, Simone Finzi, Lucia Mauri, Shahrbanou Javadiyan, Emmanuelle Souzeau, Tiger Zhou, Alex W. Hewitt, Bethany Kloss, Kathryn P. Burdon, David A. Mackey, Keri F. Allen, Jonathan B. Ruddle, Sing-Hui Lim, Steve Rozen, Khanh-Nhat Tran-Viet, Xiaorong Liu, Simon John, Janey L. Wiggs, Francesca Pasutto, Jamie E. Craig, Jing Jin, Susan E. Quaggin, Terri L. Young

×

Figure 4

Splice donor site mutations lead to cryptic splice site use or exon skipping.

Options: View larger image (or click on image) Download as PowerPoint
Splice donor site mutations lead to cryptic splice site use or exon skip...
(A and B) Splicing construct minigenes were generated by incorporating genomic regions of the TEK gene into the pSPL3 vector via XhoI and BamHI restriction sites. Vector exons, V1 and V2, are depicted as black boxes and TEK exons 5, 6, and 22 are in gray. WT and mutant splicing products, with included exon sizes in base pairs, are indicated by dashed lines above and below the construct, respectively. The locations of the splice site mutations are shown (*). (A) WT (WT-5) and mutant (M-5) genomic fragments containing TEK exons 5 and 6 were used to model the c.760+2T>C mutation from family 7. (B) WT (WT-22) and mutant (M-22) genomic fragments containing TEK exon 22 were used to model the c.760+2T>C mutation from family 8. (C) Gel electrophoresis of RT-PCR products from transfected Cos-7 cells. Vector exon-specific primers are indicated by arrows in A and B. TF -ve, cells transfected with PBS only; PCR -ve, PCR-negative control. WT and mutant transcript content, determined by Sanger sequencing, is depicted to the right of the gel image. The additional 21 bp of intron 5 sequence identified within the M5 transcript is shown incorporating a premature termination codon between exons 5 and 6.