RXR gamma null mice are apparently normal and compound RXR alpha +/-/RXR beta -/-/RXR gamma -/- mutant mice are viable.

The RXR gamma (RXR, retinoid X receptor) gene was disrupted in the mouse. Homozygous mutant mice developed normally and were indistinguishable from their RXR gamma +/- or wild-type littermates with respect to growth, fertility, viability, and apparent behavior in the animal facility. Moreover, RXR alpha -/-/RXR gamma -/- and RXR beta -/-/RXR gamma -/- mutant phenotypes were indistinguishable from those of RXR alpha -/- and RXR beta -/- mutants, respectively. Strikingly, RXR alpha +/-/RXR beta -/-/RXR gamma -/- triple mutants were viable. Thus, it appears that RXR gamma does not exert any essential function that cannot be performed by RXR alpha or RXR beta, and one copy of RXR alpha is sufficient to perform most of the functions of the RXRs. IMAGES:

本研究在小鼠模型中对类视黄醇X受体γ（RXR gamma，RXR为retinoid X receptor的缩写）基因进行了功能敲除。纯合突变小鼠发育正常，在生长、生育能力、生存活力以及动物饲养设施内的表观行为方面，均与RXRγ杂合（RXR gamma +/-）或野生型同窝仔鼠无明显差异。此外，RXRα-/-/RXRγ-/-双突变体的表型与RXRα-/-单突变体完全一致，RXRβ-/-/RXRγ-/-双突变体的表型亦与RXRβ-/-单突变体无差异。值得注意的是，RXRα+/-/RXRβ-/-/RXRγ-/-三突变体仍可存活。综上，类视黄醇X受体γ（RXR gamma）并不具备无法由RXRα或RXRβ替代的必需功能；且单拷贝的RXRα即可完成类视黄醇X受体家族的绝大多数功能。图片：