The platinum-carbon replica technique was applied to rat hepatocyte monolayers to visualize the distribution of the receptor responsible for the clearance of asialoglycoproteins. In a first series of experiments, hepatocytes were mildly fixed, either immediately after transfer to 4 degrees C, or after up to 24 h of incubation at 4 degrees C in the presence or absence of soluble asialofetuin (ASF). The asialoglycoprotein receptors were then immunolabeled by a rabbit antiserum followed by protein A-gold complexes. Average labeling was 41 +/- 2 particles x microns -2 (mean +/- SEM, n = 50), corresponding to an efficiency of about 25% as compared to radioligand binding data. Nearest neighbor analysis of gold particles showed an almost random distribution on cells incubated without asialofetuin, but significant clustering after exposure to the ligand. In a second series of experiments, hepatocytes were incubated at 4 degrees C for 2 or 24 h with asialofetuin adsorbed onto 15-nm gold particles (2 x 10(12) particles x ml-1, 32 molecules x particle-1), then fixed. On average, 20 +/- 2 (n = 14) and 38 +/- 6 (n = 19) particles x microns -2 were observed after 2 and 24 h, respectively. By comparison to control preparations, clustering of particles was found at both time intervals, although no significant difference could be detected between 2 and 24 h using the Kolmogorov-Smirnov test when the abundance of particles was taken into consideration. Summarizing, (1) in absence of ligand, the asialoglycoprotein receptor is almost randomly distributed on rat hepatocytes, (2) both soluble ASF and ASF-gold complexes induce receptor clustering, (3) even at 4 degrees C, the plasma membrane remains sufficiently fluid for receptor clustering.
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Pharmaceutics
January 2025
Department of Pharmaceutical Bioscience, Translational Drug Discovery and Development, Uppsala University, SE-75124 Uppsala, Sweden.
: N-acetyl-galactosamine small interfering RNAs (GalNAc-siRNA) are an emerging class of drugs due to their durable knockdown of disease-related proteins. Direct conjugation of GalNAc onto the siRNA enables targeted uptake into hepatocytes via GalNAc recognition of the Asialoglycoprotein Receptor (ASGPR). With a transient plasma exposure combined with a prolonged liver half-life, GalNAc-siRNA exhibits distinct disposition characteristics.
View Article and Find Full Text PDFEng Life Sci
January 2025
Analytical Development & Analytical Attribute Science in Biologics Bristol Myers Squibb Devens Massachusetts USA.
This study emphasizes the critical importance of closely monitoring and controlling the sialic acid content in therapeutic glycoproteins, including EPO, interferon-γ, Orencia, Enbrel, and others, as the level of sialylation directly impacts their pharmacokinetics (PK), immunogenicity, potency, and overall clinical performance due to its influence on protein clearance via hepatic asialoglycoprotein receptors (ASGPR). The ASGPR recognizes and binds to glycoproteins exposed to terminal galactose or N-acetylgalactosamine residues, leading to receptor-mediated endocytosis. Recent studies have demonstrated that sialylation of O-linked glycan plays a role in protecting against macrophage galactose lectin (MGL)-mediated clearance.
View Article and Find Full Text PDFFront Pharmacol
January 2025
Hubei Shizhen Laboratory, Wuhan, China.
Introduction: The mortality rate for liver cancer is extremely high but clinical treatments have not made much progress, so it is necessary to develop anticancer agents with lower toxicities and more effective liver-targeting drug delivery systems (LTDDSs). At present, LTDDSs mediated by the asialoglycoprotein receptor (ASGPR) show excellent effects at improving the liver-targeting and antitumor effects of drugs. However, the galactosyl ligands are typically prepared by chemical synthesis and have some shortcomings.
View Article and Find Full Text PDFJ Med Chem
January 2025
Department of Ophthalmology, Tianjin Medical University General Hospital, International Joint Laboratory of Ocular Diseases (Ministry of Education), Tianjin Key Laboratory of Ocular Trauma, Tianjin Institute of Eye Health and Eye Diseases, China-U.K. "Belt and Road" Ophthalmology Joint Laboratory, Laboratory of Molecular Ophthalmology, The Province and Ministry Co-sponsored Collaborative Innovation Center for Medical Epigenetics, Tianjin Medical University, Tianjin 300070, China.
Hepatitis C virus (HCV) infection is a major cause of chronic liver disease. Although interferon-free direct-acting antivirals have led to significant advancements in the treatment of HCV infection, the high genetic variability of the virus and the emergence of acquired drug resistance pose potential threats to their effectiveness. In this study, we develop a broad-spectrum aptamer-based proteolysis targeting chimera, designated dNS5B, which effectively degrades both pan-genotypic NS5B polymerase and drug-resistant mutants through ubiquitin proteasome system.
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Stem Cells Technology Research Center, Shiraz University of Medical Sciences, Shiraz, Iran; Department of Epidemiology, West Kazakhstan Marat Ospanov Medical University, Aktobe, Kazakhstan; Department of Natural Sciences, West Kazakhstan Marat Ospanov Medical University, Aktobe, Kazakhstan. Electronic address:
Microplastics (MPs) are known as substantial environmental and health threats because of their pervasive existence and potential function in human diseases. This study is the first research in which a comprehensive analysis of various impacts of MPs on cancer cells is performed through pharmacological and in silico approaches. Moreover, our results demonstrate that MPs have both promotive and suppressive impacts on cancer cells, changing some of the important features of these kinds of cells including cellular viability, migration, metastasis, and apoptosis.
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