The UPK2 gene encodes Uroplakin II, a 15-kDa integral membrane protein that is a key component of the asymmetric unit membrane (AUM) found in urothelial cells. This highly specialized biomembrane forms apical plaques, primarily in the urothelium lining the bladder, ureters, and renal pelvis, where it strengthens the urothelium and prevents cell rupture during bladder distention, contributing to the permeability barrier ^[1]. UPK2 expression is highly specific to urothelial cells, making it a valuable diagnostic marker, particularly for urothelial carcinoma (UC), where it is frequently expressed in both non-invasive and invasive forms and can be detected in the peripheral blood of bladder cancer patients. Associated diseases include transitional cell carcinoma (a type of bladder cancer), and mutations or altered expression have been linked to congenital urinary tract anomalies and interstitial cystitis/bladder pain syndrome (IC/BPS) in some studies ^[2-3]. Upk2-Cre mice are generated via transgenic (TG) genome editing, carrying the Cre recombinase gene cassette driven by the endogenous promoter of the mouse Upk2 gene. When crossed with mice containing loxP sites, Cre-mediated recombination between loxP sites is expected to occur in the bladder urothelium and Upk2-positive cells of the offspring.

Upk2 is located on chromosome 9 of mice. SgRNA and ssDNA will be designed using Nuclease Technology; Upk2 conditional knockout mice will be obtained by high-throughput electroporation of fertilized eggs. After sexual maturity, sperm will be collected for cryopreservation.