The waved with open eyelids (woe) Locus Is a Hypomorphic Mouse Mutation in Adam17

Abstract

The waved with open eyes (woe) locus is a spontaneous recessive mouse mutation that exhibits wavy fur, eyelids open at birth, and enlarged heart and esophagus. In this study, we confirmed the previously identified woe phenotypes and additionally identified anterior eye segment defects, absence of the meibomian glands, and defects in the semilunar cardiac valves. Positional cloning identified a C794T substitution in the Adam17 gene that ablates a putative exonic splicing enhancer (ESE) sequence in exon 7 resulting in aberrant Adam17 splicing. The predominant woe transcript, Adam17 Dexon7, lacks exon 7 resulting in an in-frame deletion of 90 bp and a putative Adam17 D252-281 protein lacking residues 252-281 from the metalloprotease domain. Western blot analysis in woe identified only the precursor form of Adam17 D252-281 protein. Absence of cleavage of the prodomain renders Adam17 D252-281 functionally inactive; however, constitutive and stimulated shedding of Adam17 substrates was detected in woe at significantly reduced levels. This residual Adam17 shedding activity in woe most likely originates from full-length Adam17 T265M encoded by the Adam17 C794T transcript identified expressed at severely reduced levels. These results show that even small amounts of functional Adam17 allow woe mice to survive into adulthood. In contrast to Adam17 À/À mice that die at birth, the viability of woe mice provides an excellent opportunity for studying the role of Adam17 throughout postnatal development and homeostasis.

Genetic variants of Adam17 differentially regulate TGFβ signaling to modify vascular pathology in mice and humans

“…In fact, the p.Ileu613Val variant is located within the cysteine-rich substrate recognition domain (43); thus, variation in Adam17 p.Asn113-Val613 may preferentially affect TβRI signaling over that of other substrates, such as TNFα. If the C57 ADAM17 variant reduced activation of EGFR, TGFα or TNFα processing, wild-type C57 mice might be expected to present with dramatic phenotypes, such as perinatal lethality (44) or inflammatory skin and bowel disease (45), observed in mice or humans lacking functional ADAM17, or with wavey fur and open eyelids, as observed in a more severe murine ADAM17 hypomorph (46), which is clearly not the case.…”

ADAM17 Transactivates EGFR Signaling during Embryonic Eyelid Closure

“…6 Dsk5 mice were provided by David Threadgill, PhD, from the University of North Carolina. All mice were used with strict adherence to the guidelines set forth in the ARVO Statement for the Use of Animals in Ophthalmic and Vision Research.…”

“…4,5 Recently, an Adam17 c.C794T substitution was identified in a mouse termed waved with open eyelids (woe) that resulted in aberrant Adam17 splicing and severely reduced ADAM17 sheddase activity. 6 Although severely reduced, the ADAM17 sheddase activity was sufficient to reduce the severity of cardiac valve phenotypes associated with the absence of ADAM17 function, thus allowing woe mice to survive into adulthood. [4][5][6] In addition to mild cardiac abnormalities, woe mice exhibit EOB and wavy fur phenotypes 6 similar to those of Adam17 À/À mice.…”

“…6 Although severely reduced, the ADAM17 sheddase activity was sufficient to reduce the severity of cardiac valve phenotypes associated with the absence of ADAM17 function, thus allowing woe mice to survive into adulthood. [4][5][6] In addition to mild cardiac abnormalities, woe mice exhibit EOB and wavy fur phenotypes 6 similar to those of Adam17 À/À mice. 4,5 The survival of woe mice into adulthood facilitated the identification of previously unknown phenotypes associated with ADAM17 deficiency such as ocular anterior segment abnormalities and the absence of meibomian glands.…”

“…4,5 The survival of woe mice into adulthood facilitated the identification of previously unknown phenotypes associated with ADAM17 deficiency such as ocular anterior segment abnormalities and the absence of meibomian glands. 6 The presence of the EOB phenotype in woe and Adam17 À/À mice provided convincing evidence that ADAM17 is critical for proper embryonic eyelid closure; however, the precise role of ADAM17 during this process has not yet been established. Embryonic eyelid closure is common to all mammals where, following formation, eyelids migrate across the cornea, fuse together, and ultimately reopen.…”