[Uroplakins as markers of diseases of the urinary system]

An unique element of bladder urothelium is a multilayer membrane, which extends from the renal pelvis to the urethra. Urotelial membrane covers more than 90% of the inner portion of the bladder and is in direct contact with urine. Urothelium is composed of characteristic two-dimensional, asymmetric plaques, composed of uroplakins (UP), differentiated, hexagonally arranged proteins. The unique structure of the urothelial plaques determines the tightness, integrity and strength of the urothelium, prevent rupture of the walls of the bladder during the build-up of urine in the bladder and protects against the toxic ingredients. Uroplakins are tissue-specific, heterogeneous glycoproteins whose oligosaccharide part plays a specific role in the structure and function of urothelium. Disorders of normal expression of uroplakins are highly associated with the pathogenesis in infection and urinary tract malignancies, primary vesico-urinary reflux, hydronephrosis and renal impairment. The emergence of uroplakins in urine and / or plasma may have a potential role in the early detection of bladder tumors. In this paper, the structure and function of uroplakins types Ia, Ib, II, IIIa, their natural oligomerization into heterodimers, tetramers and hexamers, and the role in the construction of asymmetric and flexible urothelial epithelium is presented. We discuss the potential role of uroplakins in laboratory diagnosis of umbrella cell differentiation and in the screening analysis of urinary bladder disorders. The possibilities of using the knowledge of uroplakins in clinical settings as well as in modern strategies for treatment of infectious diseases and cancer of the urinary tract are highlighted.