Intact protein core structure is essential for protein-binding, mononuclear cell proliferating, and neutrophil phagocytosis-enhancing activities of normal human urinary Tamm-Horsfall glycoprotein.
Tamm-Horsfall glycoprotein (THP) is synthesized in the particular sites of renal tubules acting as a defense molecule in the urinary system. In the present study, we found that THP contained high amount of Siaalpha(2,3)Gal/GalNAc, moderate amount of beta(1,4)GlcNAc oligomers and GlcNAc/branched mannose, and low amount of mannose residues, but no Siaalpha(2,6)Gal/GalNAc, in the side-chains of the molecule. THP exhibited high binding affinity with human TNF-alpha, IgG, C1q and BSA, moderate binding affinity with IL-8, and low binding affinity with IL-6 and IFN-gamma. For exploring the role of carbohydrate side-chains and protein core in the protein-binding and cell-stimulating activities, THP was enzyme-digested with carbohydrate-specific [neuraminidase (Nase), beta-galactosidase (Gase)], protein-specific [V8 protease (V8), proteinase K (PaseK)] and glycoconjugate-specific [carboxypeptidase Y (Case), O-sialoglycoprotein endopeptidase (Oase)] degrading enzymes. We found that THP digested with V8, Oase, and PaseK, significantly reduced its protein-binding, mononuclear cell proliferating, and neutrophil phagocytosis-enhancing activities. These results suggest that the intact protein core structure, but not carbohydrate side-chains, is essential for pleotropic functions of THP molecule.
Wu
Tsai-Hung
TH
Institute of Clinical Medicine and Section of Nephrology, National Yang-Ming University College of Medicine, Taipei, Taiwan.
Hsieh
Song-Chou
SC
Yu
Chih-Yao
CY
Lee
Yi-Fang
YF
Tsai
Chang-Youh
CY
Yu
Chia-Li
CL
D000818:Animals; D002240:Carbohydrate Sequence; D002417:Cattle; D049109:Cell Proliferation; D006031:Glycosylation; D006801:Humans; D007963:Leukocytes, Mononuclear / Q000166:cytology* / Q000201:enzymology; D008969:Molecular Sequence Data; D009088:Mucoproteins / Q000737:chemistry* / Q000378:metabolism / Q000502:physiology* / Q000652:urine; D009504:Neutrophils / Q000201:enzymology / Q000502:physiology*; D010587:Phagocytosis / Q000502:physiology*; D011485:Protein Binding / Q000502:physiology; D058949:Uromodulin
D009088:Mucoproteins; C548612:UMOD protein, human; D058949:Uromodulin