Biomaterial Database

At reduced temperature, endocytic membrane traffic is blocked in multivesicular carrier endosomes in rat cardiac myocytes. 1998

E L Punnonen, and K Ryhänen, and V S Marjomäki

Department of Biological and Environmental Science, University of Jyväskylä, Finland.

Temperatures around 20 degrees C are known to block degradation of endocytosed material by preventing its transport to lysosomes, accordingly reduced temperature has been widely used to define endosomes. Newer studies have revealed that the low temperature block is proximal to perinuclear late endosomes, but it is not clear whether the block is already in early endosomes, or whether the traffic proceeds to multivesicular carrier endosomes which mediate transport from early to late compartments. We have now focused on this problem using rat cardiac myocytes. First, cell fractionation on Percoll gradients showed that at reduced temperatures (22 degrees C and 26 degrees C), with prolonged chase periods, endocytosed horseradish peroxidase was able to proceed from early endosomes to later compartments but not up to lysosomes. Further, microscopic experiments with fluorescent endocytic marker FITC-dextran showed that the marker did not accumulate in the perinuclear area, as was the case at 37 degrees C, but stayed in peripheral cytoplasm at reduced temperatures, even after 16-h chase. Second, electron microscopic pulse labeling showed that, at 22 degrees C, endocytosed gold particles (BSA-gold) are transported to compartments not accessible to HRP internalised later to early endosomes. Thus, these gold particles had reached a later compartment. Morphologically these vesicles were multivesicular bodies of 0.5-1 microm in diameter. Third, we used fluorescence microscopy to study the effect of reduced temperature on transferrin uptake and recycling. At 17 degrees C and 22 degrees C, transferrin was internalized normally to peripheral (sorting) and perinuclear (recycling) vesicles. If transferrin was first taken up at 37 degrees C, and the cells were then chased at various temperatures from 37 degrees C to 17 degrees C, the recycling was slowed down but not entirely blocked at the reduced temperatures. From these results we can conclude that (1) endocytic traffic is blocked in multivesicular carrier endosomes at and below 26 degrees C, and that (2) reduced temperature slows down transport in the recycling pathway, without a complete block.

UI	MeSH Term	Description	Entries
D007425	Intracellular Membranes	Thin structures that encapsulate subcellular structures or ORGANELLES in EUKARYOTIC CELLS. They include a variety of membranes associated with the CELL NUCLEUS; the MITOCHONDRIA; the GOLGI APPARATUS; the ENDOPLASMIC RETICULUM; LYSOSOMES; PLASTIDS; and VACUOLES.	Membranes, Intracellular,Intracellular Membrane,Membrane, Intracellular
D008856	Microscopy, Fluorescence	Microscopy of specimens stained with fluorescent dye (usually fluorescein isothiocyanate) or of naturally fluorescent materials, which emit light when exposed to ultraviolet or blue light. Immunofluorescence microscopy utilizes antibodies that are labeled with fluorescent dye.	Fluorescence Microscopy,Immunofluorescence Microscopy,Microscopy, Immunofluorescence,Fluorescence Microscopies,Immunofluorescence Microscopies,Microscopies, Fluorescence,Microscopies, Immunofluorescence
D009206	Myocardium	The muscle tissue of the HEART. It is composed of striated, involuntary muscle cells (MYOCYTES, CARDIAC) connected to form the contractile pump to generate blood flow.	Muscle, Cardiac,Muscle, Heart,Cardiac Muscle,Myocardia,Cardiac Muscles,Heart Muscle,Heart Muscles,Muscles, Cardiac,Muscles, Heart
D011992	Endosomes	Cytoplasmic vesicles formed when COATED VESICLES shed their CLATHRIN coat. Endosomes internalize macromolecules bound by receptors on the cell surface.	Receptosomes,Endosome,Receptosome
D002352	Carrier Proteins	Proteins that bind or transport specific substances in the blood, within the cell, or across cell membranes.	Binding Proteins,Carrier Protein,Transport Protein,Transport Proteins,Binding Protein,Protein, Carrier,Proteins, Carrier
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
D003080	Cold Temperature	An absence of warmth or heat or a temperature notably below an accustomed norm.	Cold,Cold Temperatures,Temperature, Cold,Temperatures, Cold
D004622	Embryo, Mammalian	The entity of a developing mammal (MAMMALS), generally from the cleavage of a ZYGOTE to the end of embryonic differentiation of basic structures. For the human embryo, this represents the first two months of intrauterine development preceding the stages of the FETUS.	Embryonic Structures, Mammalian,Mammalian Embryo,Mammalian Embryo Structures,Mammalian Embryonic Structures,Embryo Structure, Mammalian,Embryo Structures, Mammalian,Embryonic Structure, Mammalian,Embryos, Mammalian,Mammalian Embryo Structure,Mammalian Embryonic Structure,Mammalian Embryos,Structure, Mammalian Embryo,Structure, Mammalian Embryonic,Structures, Mammalian Embryo,Structures, Mammalian Embryonic
D004705	Endocytosis	Cellular uptake of extracellular materials within membrane-limited vacuoles or microvesicles. ENDOSOMES play a central role in endocytosis.	Endocytoses
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