Exome sequencing identifies a nonsense mutation in Fam46a associated with bone abnormalities in a new mouse model for skeletal dysplasia.

We performed exome sequencing for mutation discovery of an ENU (N-ethyl-N-nitrosourea)-derived mouse model characterized by significant elevated plasma alkaline phosphatase (ALP) activities in female and male mutant mice, originally named BAP014 (bone screen alkaline phosphatase #14). We identified a novel loss-of-function mutation within the Fam46a (family with sequence similarity 46, member A) gene (NM_001160378.1:c.469G>T, NP_001153850.1:p.Glu157*). Heterozygous mice of this mouse line (renamed Fam46a (E157*Mhda)) had significantly high ALP activities and apparently no other differences in morphology compared to wild-type mice. In contrast, homozygous Fam46a (E157*Mhda) mice showed severe morphological and skeletal abnormalities including short stature along with limb, rib, pelvis, and skull deformities with minimal trabecular bone and reduced cortical bone thickness in long bones. ALP activities of homozygous mutants were almost two-fold higher than in heterozygous mice. Fam46a is weakly expressed in most adult and embryonic tissues with a strong expression in mineralized tissues as calvaria and femur. The FAM46A protein is computationally predicted as a new member of the superfamily of nucleotidyltransferase fold proteins, but little is known about its function. Fam46a (E157*Mhda) mice are the first mouse model for a mutation within the Fam46a gene.

Engineering of Conditional Class I Hdac Knockout Mice and Generation of a Time-Spatial Knockout by a Dual Recombination System.

The protein sequences of class I HDACs in mice and humans are 96-99 % identical. These highly conserved proteins have crucial roles in biological processes, such as proliferation and development, which is reflected in the lethality that occurs in conventional whole body knockout mice. Therefore, conditional knockouts are inevitable to investigate the functions of class I HDACs in mice. Here, we describe the generation of conditional class I Hdac knockout mice, using Hdac1 as an example. We explain a relatively quick procedure to generate the necessary target vectors by recombination-mediated genetic engineering and gateway techniques. Furthermore, we show how to culture, target, and screen for positively recombined ES cells. Additionally, we present a dual recombination system, which allows the deletion of class I Hdacs at any time by a tamoxifen inducible Cre.