Biomaterial Database

Effect of galactose on binding and endocytosis of asialoglycoprotein in cultured rat hepatocytes. 1998

S Hata, and K Ishii

Second Department of Internal Medicine, Toho University School of Medicine, Tokyo, Japan.

BACKGROUND 99mTc-diethylenetriaminepentaacetic acid-galactosyl-human serum albumin (99mTc-GSA) has been applied clinically in scintigraphy to estimate functioning liver mass, but it is not so sensitive in differentiating mild liver injury from normal liver. 99mTc-GSA is thought to bind to the asialoglycoprotein receptor (ASGP-R) and is then internalized and degraded in the hepatocytes. The aim of this study is to know whether D-galactose inhibits GSA binding or internalization to hepatocyes because ASGP-R recognizes galactose residues of ligands. METHODS Isolated rat hepatocytes were obtained by collagenase perfusion, pre-cultured for 2 h after plating, and then cultured for 16 to 18 h until use. The effect of galactose on GSA binding and internalization into cells was investigated by using cultured hepatocytes. RESULTS Galactose non-competitively inhibited GSA binding to cultured hepatocytes, but its Ki value was quite high (505 +/- 38 mM). Galactose significantly inhibited GSA internalization into hepatocytes at 27 mM. CONCLUSIONS It was clarified that D-galactose inhibited GSA internalization rather than binding at a low concentration. Further in vivo studies in rats are needed to know whether an administration of galactose prior to performing 99mTc-GSA scintigraphy can brake it possible to estimate the functioning mass in mild liver injury.

UI	MeSH Term	Description	Entries
D008099	Liver	A large lobed glandular organ in the abdomen of vertebrates that is responsible for detoxification, metabolism, synthesis and storage of various substances.	Livers
D008297	Male		Males
D011956	Receptors, Cell Surface	Cell surface proteins that bind signalling molecules external to the cell with high affinity and convert this extracellular event into one or more intracellular signals that alter the behavior of the target cell (From Alberts, Molecular Biology of the Cell, 2nd ed, pp693-5). Cell surface receptors, unlike enzymes, do not chemically alter their ligands.	Cell Surface Receptor,Cell Surface Receptors,Hormone Receptors, Cell Surface,Receptors, Endogenous Substances,Cell Surface Hormone Receptors,Endogenous Substances Receptors,Receptor, Cell Surface,Surface Receptor, Cell
D002478	Cells, Cultured	Cells propagated in vitro in special media conducive to their growth. Cultured cells are used to study developmental, morphologic, metabolic, physiologic, and genetic processes, among others.	Cultured Cells,Cell, Cultured,Cultured Cell
D004705	Endocytosis	Cellular uptake of extracellular materials within membrane-limited vacuoles or microvesicles. ENDOSOMES play a central role in endocytosis.	Endocytoses
D005690	Galactose	An aldohexose that occurs naturally in the D-form in lactose, cerebrosides, gangliosides, and mucoproteins. Deficiency of galactosyl-1-phosphate uridyltransferase (GALACTOSE-1-PHOSPHATE URIDYL-TRANSFERASE DEFICIENCY DISEASE) causes an error in galactose metabolism called GALACTOSEMIA, resulting in elevations of galactose in the blood.	D-Galactose,Galactopyranose,Galactopyranoside,D Galactose
D006801	Humans	Members of the species Homo sapiens.	Homo sapiens,Man (Taxonomy),Human,Man, Modern,Modern Man
D000818	Animals	Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA.	Animal,Metazoa,Animalia
D001212	Asialoglycoproteins	Endogenous glycoproteins from which SIALIC ACID has been removed by the action of sialidases. They bind tightly to the ASIALOGLYCOPROTEIN RECEPTOR which is located on hepatocyte plasma membranes. After internalization by adsorptive ENDOCYTOSIS they are delivered to LYSOSOMES for degradation. Therefore receptor-mediated clearance of asialoglycoproteins is an important aspect of the turnover of plasma glycoproteins. They are elevated in serum of patients with HEPATIC CIRRHOSIS or HEPATITIS.	Asialoglycoprotein,Desialylated Glycoproteins,Glycoproteins, Desialylated
D013668	Technetium Tc 99m Aggregated Albumin	A gamma-emitting radionuclide imaging agent used for the diagnosis of diseases in many tissues, particularly in cardiovascular and cerebral circulation.	Tc 99m-Albumin,Tc 99m-Albumin Colloid,99m-Tc-HSA,99mTc-Albures,99mTc-HSA,99mTc-Human Serum Albumin,Tc-99m-HAM,Tc-99m-MAA,Tc-99m-Microalbumin,Tc-HAMM,Tc99m-Albumin,Technetium-99m Albumin Colloid,99mTc Albures,99mTc Human Serum Albumin,99mTcAlbures,Albumin Colloid, Technetium-99m,Albumin, 99mTc-Human Serum,Colloid, Tc 99m-Albumin,Colloid, Technetium-99m Albumin,Serum Albumin, 99mTc-Human,Tc 99m Albumin,Tc 99m Albumin Colloid,Tc 99m HAM,Tc 99m MAA,Tc 99m Microalbumin,Tc HAMM,Tc99m Albumin,Technetium 99m Albumin Colloid