The effect of heat shock on primary cultures of brain capillary endothelium: inhibition of assembly of zonulae occludentes and the synthesis of heat-shock proteins.
Subjecting primary cultures of bovine brain microvessel endothelial cells to thermal stress (heat shock) results in: (1) an inhibition of further tight junction assembly, (2) the disappearance and/or disassembly of tight junctions, (3) a 30-fold increase in the number of plasmic fracture (PF)-face intramembrane particles, and (4) the new and/or enhanced synthesis of at least three heat-shock polypeptides (HSPs) with molecular masses of approximately 100,000, 90,000 and 70,000. Endothelial cells which are heat-shocked and allowed to recover at 37 degrees C exhibit, within the first 2 h, a marked depression in the synthesis of HSPs and the new and/or enhanced synthesis of a 47,000 dalton "recovery" polypeptide. In later periods of recovery (2-4 h), the synthesis of this polypeptide is even more pronounced and is accompanied by the new and/or enhanced synthesis of a polypeptide(s) with a molecular mass of 35 to 37,000. The appearance of these "recovery protein(s)" in the endothelial cells is concomitant with a decrease in the number of PF-face intramembrane particles and the resumption of tight junction assembly. Results of this study suggest that some of the HSPs synthesized by thermally-stressed cultures of brain endothelial cells may activate or be directly involved in a mechanism(s) to ensure survival of these cells by decreasing membrane fluidity and stabilizing the plasma membrane of these cells. Moreover, our results also suggest that the recovery of these cells from the stress of heat shock is accompanied by the synthesis of "recovery" proteins which, in some manner, may be directly involved in, or necessary for, rapidly reversing the membrane-stabilizing effect of heat shock by promoting membrane fluidity and the apparent amplified synthesis and assembly and/or reassembly of tight junctions.
Shivers
R R
RR
Department of Zoology, University of Western Ontario, London, Canada.
Pollock
M
M
Bowman
P D
PD
Atkinson
B G
BG
D000818:Animals; D001921:Brain / Q000098:blood supply*; D002196:Capillaries / Q000378:metabolism / Q000648:ultrastructure; D002417:Cattle; D002478:Cells, Cultured; D004730:Endothelium, Vascular / Q000378:metabolism* / Q000648:ultrastructure; D005614:Freeze Fracturing; D006360:Heat-Shock Proteins / Q000096:biosynthesis*; D006358:Hot Temperature; D008854:Microscopy, Electron
D006360:Heat-Shock Proteins