Rxrb-flox Mouse

Rxrb, encoding Retinoid X receptor beta, is a member of the retinoid X receptor family of nuclear receptors involved in mediating retinoic acid effects [5]. It can form heterodimers with peroxisome proliferator-activated receptors (PPARs) and is crucial for cholesterol homeostasis, spermiation, and chromatin remodeling [3,4].

In Sertoli cells, somatic targeted inactivation of Rxrb (Rxrb(Ser-/-) mutants) leads to failure of spermatid release and cholesterol ester accumulation, causing testis degeneration, indicating its key role in male reproduction [4]. In systemic sclerosis, exome sequencing identified rs17847931 in RXRB as a susceptibility variant, suggesting its involvement in antifibrotic activity in skin and chromatin remodeling [1]. In cancer, the RAB39A-RXRB axis was found to be important for cancer development and stemness, with RXRB being a major effector of RAB39A [2].

In conclusion, Rxrb plays essential roles in male reproduction, is associated with disease susceptibilities like systemic sclerosis, and is involved in cancer-related processes. Mouse models, such as the Rxrb(Ser-/-) mutants, have been instrumental in revealing its functions in male reproductive pathophysiology, while human-based genetic studies have shed light on its role in autoimmune and cancer-related conditions.