Blind sterile 2 (bs2), a hypomorphic mutation in Agps, results in cataracts and male sterility in mice.

Blind sterile 2 (bs2) is a spontaneous autosomal recessive mouse mutation exhibiting cataracts and male sterility. Detailed clinical and histological evaluation revealed that bs2 mice have cataracts resulting from severely disrupted lens fiber cells. Analysis of bs2 testes revealed the absence of mature sperm and the presence of large multinucleate cells within the lumens of seminiferous tubules. Linkage analysis mapped the bs2 locus to mouse chromosome 2, approximately 45cM distal from the centromere. Fine mapping established a 3.1Mb bs2 critical region containing 19 candidate genes. Sequence analysis of alkylglycerone-phosphate synthase (Agps), a gene within the bs2 critical region, revealed a G to A substitution at the +5 position of intron 14. This mutation results in two abundantly expressed aberrantly spliced Agps transcripts: Agps(∆exon14) lacking exon 14 or Agps(exon∆13-14) lacking both exons 13 and 14 as well as full-length Agps transcript. Agps is a peroxisomal enzyme which catalyzes the formation of the ether bond during the synthesis of ether lipids. Both aberrantly spliced Agps(∆exon14) and Agps(exon∆13-14) transcripts led to a frame shift, premature stop and putative proteins lacking the enzymatic FAD domain. We present evidence that bs2 mice have significantly decreased levels of ether lipids. Human mutations in Agps result in rhizomelic chondrodysplasia punctata type 3 (RCDP3), a disease for which bs2 is the only genetic model. Thus, bs2 is a hypomorphic mutation in Agps, and represents a useful model for investigation of the tissue specificity of ether lipid requirements which will be particularly valuable for elucidating the mechanism of disease phenotypes resulting from ether lipid depletion.

The waved with open eyelids (woe) locus is a hypomorphic mouse mutation in Adam17.

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(Delta)(exon7), lacks exon 7 resulting in an in-frame deletion of 90 bp and a putative Adam17(Delta252-281) protein lacking residues 252-281 from the metalloprotease domain. Western blot analysis in woe identified only the precursor form of Adam17(Delta252-281) protein. Absence of cleavage of the prodomain renders Adam17(Delta252-281) 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(-/-) 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.