Biomaterial Database

Lysosomes and pancreatic islet function. Time course of insulin biosynthesis, insulin secretion, and lysosomal transformation after rapid changes in glucose concentration. 1988

A H Landström, and J Westman, and L A Borg

Department of Medical Cell Biology, University of Uppsala, Sweden.

The aim of this study was to estimate the time course of lysosomal transformations associated with crinophagy, i.e., the degradation of insulin within lysosomes, in the beta-cells of pancreatic islets. Primary and secondary lysosomes were identified in mouse islet beta-cells and subjected to ultrastructural morphometry. Islets from an in situ preparation were compared with isolated islets incubated in vitro. Under the in vitro conditions, the islets were initially exposed to 28 or 3.3 mM glucose for 24 h. Then the glucose concentration was rapidly changed to 3.3 and 28 mM glucose, respectively, and the islets were incubated for up to an additional 24 h. The beta-cell lysosomes were analyzed and related to alterations in insulin biosynthesis and secretion and islet insulin content after the rapid change in glucose concentration. In vivo, the beta-cell lysosomal population was predominantly composed of secondary lysosomes, which frequently contained secretory granule cores. After the initial 24-h period at 3.3 mM glucose, the volume density and the average volume of the secondary beta-cell lysosomes were increased, suggesting increased crinophagic activity. The mean diameter of the primary beta-cell lysosomes was decreased after 24 h at either 28 or 3.3 mM glucose. The change in glucose from 28 to 3.3 mM resulted in alterations in insulin biosynthesis and secretion, leading to an accumulation of insulin within the beta-cells. Lysosomal transformations suggestive of increased crinophagy were observed 24 h after the alteration in glucose concentration. The change from 3.3 to 28 mM glucose resulted in a parallel increase in insulin biosynthesis and secretion without a change in islet insulin content.(ABSTRACT TRUNCATED AT 250 WORDS)

UI	MeSH Term	Description	Entries
D007328	Insulin	A 51-amino acid pancreatic hormone that plays a major role in the regulation of glucose metabolism, directly by suppressing endogenous glucose production (GLYCOGENOLYSIS; GLUCONEOGENESIS) and indirectly by suppressing GLUCAGON secretion and LIPOLYSIS. Native insulin is a globular protein comprised of a zinc-coordinated hexamer. Each insulin monomer containing two chains, A (21 residues) and B (30 residues), linked by two disulfide bonds. Insulin is used as a drug to control insulin-dependent diabetes mellitus (DIABETES MELLITUS, TYPE 1).	Iletin,Insulin A Chain,Insulin B Chain,Insulin, Regular,Novolin,Sodium Insulin,Soluble Insulin,Chain, Insulin B,Insulin, Sodium,Insulin, Soluble,Regular Insulin
D007515	Islets of Langerhans	Irregular microscopic structures consisting of cords of endocrine cells that are scattered throughout the PANCREAS among the exocrine acini. Each islet is surrounded by connective tissue fibers and penetrated by a network of capillaries. There are four major cell types. The most abundant beta cells (50-80%) secrete INSULIN. Alpha cells (5-20%) secrete GLUCAGON. PP cells (10-35%) secrete PANCREATIC POLYPEPTIDE. Delta cells (~5%) secrete SOMATOSTATIN.	Islands of Langerhans,Islet Cells,Nesidioblasts,Pancreas, Endocrine,Pancreatic Islets,Cell, Islet,Cells, Islet,Endocrine Pancreas,Islet Cell,Islet, Pancreatic,Islets, Pancreatic,Langerhans Islands,Langerhans Islets,Nesidioblast,Pancreatic Islet
D008247	Lysosomes	A class of morphologically heterogeneous cytoplasmic particles in animal and plant tissues characterized by their content of hydrolytic enzymes and the structure-linked latency of these enzymes. The intracellular functions of lysosomes depend on their lytic potential. The single unit membrane of the lysosome acts as a barrier between the enzymes enclosed in the lysosome and the external substrate. The activity of the enzymes contained in lysosomes is limited or nil unless the vesicle in which they are enclosed is ruptured or undergoes MEMBRANE FUSION. (From Rieger et al., Glossary of Genetics: Classical and Molecular, 5th ed).	Autolysosome,Autolysosomes,Lysosome
D008297	Male		Males
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
D003594	Cytoplasmic Granules	Condensed areas of cellular material that may be bounded by a membrane.	Cytoplasmic Granule,Granule, Cytoplasmic,Granules, Cytoplasmic
D005947	Glucose	A primary source of energy for living organisms. It is naturally occurring and is found in fruits and other parts of plants in its free state. It is used therapeutically in fluid and nutrient replacement.	Dextrose,Anhydrous Dextrose,D-Glucose,Glucose Monohydrate,Glucose, (DL)-Isomer,Glucose, (alpha-D)-Isomer,Glucose, (beta-D)-Isomer,D Glucose,Dextrose, Anhydrous,Monohydrate, Glucose
D000078790	Insulin Secretion	Production and release of insulin from PANCREATIC BETA CELLS that primarily occurs in response to elevated BLOOD GLUCOSE levels.	Secretion, Insulin
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
D051379	Mice	The common name for the genus Mus.	Mice, House,Mus,Mus musculus,Mice, Laboratory,Mouse,Mouse, House,Mouse, Laboratory,Mouse, Swiss,Mus domesticus,Mus musculus domesticus,Swiss Mice,House Mice,House Mouse,Laboratory Mice,Laboratory Mouse,Mice, Swiss,Swiss Mouse,domesticus, Mus musculus