Biomaterial Database

Dependence of epithelial intercellular junction biogenesis on thapsigargin-sensitive intracellular calcium stores. 1996

R O Stuart, and A Sun, and K T Bush, and S K Nigam

Renal Division, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts 02115, USA.

Perturbation of potentially regulatable endoplasmic reticulum (ER) calcium stores with the Ca-ATPase inhibitor, thapsigargin (TG), perturbs the formation of desmosomes and tight junctions during polarized epithelial cell biogenesis, despite the development of cell contact. In a Madin-Darby canine kidney cell model for intercellular junction assembly, TG treatment inhibited the development of transepithelial electrical resistance (TER), a measure of tight junction assembly, in a dose-dependent manner. The TG-induced inhibition of tight junction assembly was paralleled by a defect in the sorting of the tight junction protein, ZO-1. An even more dramatic delay in sorting of the desmosomal protein, desmoplakin, was observed in the presence of TG. In addition, while both ZO-1 and desmoplakin-I in control cells were shown to become associated with the Triton X-100 insoluble cytoskeleton during intercellular junction assembly, prior treatment with 100 nM TG diminished this biochemical stabilization into the detergent-insoluble fraction, particularly in the case of ZO-1. Although spectrofluorimetric measurements in fura-2 loaded Madin-Darby canine kidney cells confirmed the occurrence of TG-mediated release of calcium from internal stores, total cytosolic calcium during junction assembly remained similar to untreated cells. Therefore, the presence of cytosolic calcium alone is not sufficient for normal intercellular junction biogenesis if intracellular stores are perturbed by TG. The results indicate the presence of calcium-sensitive intracellular mechanisms involved in the sorting and cytoskeletal stabilization of both tight junction and desmosomes and suggest a role for calcium-dependent signaling pathways at an early (possibly common) step in polarized epithelial biogenesis.

UI	MeSH Term	Description	Entries
D007365	Intercellular Junctions	Direct contact of a cell with a neighboring cell. Most such junctions are too small to be resolved by light microscopy, but they can be visualized by conventional or freeze-fracture electron microscopy, both of which show that the interacting CELL MEMBRANE and often the underlying CYTOPLASM and the intervening EXTRACELLULAR SPACE are highly specialized in these regions. (From Alberts et al., Molecular Biology of the Cell, 2d ed, p792)	Cell Junctions,Cell Junction,Intercellular Junction,Junction, Cell,Junction, Intercellular,Junctions, Cell,Junctions, Intercellular
D007424	Intracellular Fluid	The fluid inside CELLS.	Fluid, Intracellular,Fluids, Intracellular,Intracellular Fluids
D002118	Calcium	A basic element found in nearly all tissues. It is a member of the alkaline earth family of metals with the atomic symbol Ca, atomic number 20, and atomic weight 40. Calcium is the most abundant mineral in the body and combines with phosphorus to form calcium phosphate in the bones and teeth. It is essential for the normal functioning of nerves and muscles and plays a role in blood coagulation (as factor IV) and in many enzymatic processes.	Coagulation Factor IV,Factor IV,Blood Coagulation Factor IV,Calcium-40,Calcium 40,Factor IV, Coagulation
D002460	Cell Line	Established cell cultures that have the potential to propagate indefinitely.	Cell Lines,Line, Cell,Lines, Cell
D004285	Dogs	The domestic dog, Canis familiaris, comprising about 400 breeds, of the carnivore family CANIDAE. They are worldwide in distribution and live in association with people. (Walker's Mammals of the World, 5th ed, p1065)	Canis familiaris,Dog
D004721	Endoplasmic Reticulum	A system of cisternae in the CYTOPLASM of many cells. In places the endoplasmic reticulum is continuous with the plasma membrane (CELL MEMBRANE) or outer membrane of the nuclear envelope. If the outer surfaces of the endoplasmic reticulum membranes are coated with ribosomes, the endoplasmic reticulum is said to be rough-surfaced (ENDOPLASMIC RETICULUM, ROUGH); otherwise it is said to be smooth-surfaced (ENDOPLASMIC RETICULUM, SMOOTH). (King & Stansfield, A Dictionary of Genetics, 4th ed)	Ergastoplasm,Reticulum, Endoplasmic
D004791	Enzyme Inhibitors	Compounds or agents that combine with an enzyme in such a manner as to prevent the normal substrate-enzyme combination and the catalytic reaction.	Enzyme Inhibitor,Inhibitor, Enzyme,Inhibitors, Enzyme
D004848	Epithelium	The layers of EPITHELIAL CELLS which cover the inner and outer surfaces of the cutaneous, mucus, and serous tissues and glands of the body.	Mesothelium,Epithelial Tissue,Mesothelial Tissue,Epithelial Tissues,Mesothelial Tissues,Tissue, Epithelial,Tissue, Mesothelial,Tissues, Epithelial,Tissues, Mesothelial
D000252	Calcium-Transporting ATPases	Cation-transporting proteins that utilize the energy of ATP hydrolysis for the transport of CALCIUM. They differ from CALCIUM CHANNELS which allow calcium to pass through a membrane without the use of energy.	ATPase, Calcium,Adenosinetriphosphatase, Calcium,Ca(2+)-Transporting ATPase,Calcium ATPase,Calcium Adenosinetriphosphatase,Adenosine Triphosphatase, Calcium,Ca2+ ATPase,Calcium-ATPase,ATPase, Ca2+,ATPases, Calcium-Transporting,Calcium Adenosine Triphosphatase,Calcium Transporting ATPases,Triphosphatase, Calcium Adenosine
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