Synthesis of Heat Shock Proteins in Rat Brain Cortex after Transient Ischemia

Abstract

Summary: Cell-free protein synthesis and two-dimen sional gel autoradiography were used to characterize early postischemic protein synthesis in rat neocortex. Severe forebrain ischemia was induced for 30 min (four vessel occlusion model) and followed by 3 h of recircula tion. Polysomes were isolated from the cerebral cortex, translated in vitro in a reticulocyte system, and analyzed by two-dimensional gel electrophoresis. The translation products of postischemic polysomes included a major new protein family (70 kDa) with multiple isoelectric variants that was found to comigrate with the 68-to 70-Energy failure during transient ischemia blocks protein synthesis, but when recirculation occurs, protein synthesis is impaired for at least 12-24 h after restoration of energy stores (Kleihues et aI., 1975;Cooper et al., 1977;Dienel et al., 1980; Nowak et aI., 1985). In contrast to reduced produc Dr. Kiessling's present address is Abteilung Neuropathologie, Pathologisches Institut, Albertstr. 19,7800 Freiburg, F.R.G.Abbreviations used: LSD, lysergic acid diethylamide; mRNA, messenger ribonucleic acid. 505kDa "heat shock" protein synthesized from polysomes of hyperthermic rats. Two other stress proteins (93 and 110 kDa) also appeared to be synthesized in increased amounts after ischemia. A complement of proteins that was indistinguishable from that of controls was also syn thesized after ischemia, indicating that messenger ribonu cleic acid coding for most brain proteins is preserved after ischemia and is bound to polysomes. Key Words: Brain ischemia-Heat shock proteins-Hyperthermia Protein synthesis. other brain proteins . Hyperthermia and other injurious or noxious treatments that in crease ornithine decarboxylase activity in rat brain, liver, and kidney (Dienel and Cruz, 1984) are also known to stimulate the synthesis of heat shock pro teins in rat tissues (brain, liver, heart, adrenals, etc.), in tissue culture cells, and in many other or ganisms (Ashburner and Bonner, 1979;Currie and White, 1981; Cosgrove et aI., 1982; Schlesinger et aI., 1982). In addition, a 71-kDa heat shock protein is synthesized in rat brain, liver, and kidney after carotid ligation of one animal (Currie and White, 1981) and in rat brain slices subjected to the isch emia of decapitation and tissue-slicing injury (White, 1980;1981).The purpose of this study was to determine if ri bonucleic acids (RNAs) coding for heat shock pro teins are being translated shortly (3 h) after post ischemic reperfusion when the rate of protein syn thesis is reduced by >50% and when ornithine decarboxylase activity is just beginning to increase (Dienel et aI., 1985a). We show that disaggregated poly somes derived from 3-h postischemic rat brain contain the messenger RNA (mRNA) coding for the normal complement of brain proteins and, in

Protein Synthesis in Postischemic Rat Brain: A Two-Dimensional Electrophoretic Analysis

“…The available evidence suggests that this is true for postischemic brain as weI1: NSE and the tubulins show very poor [35S]methionine incorpora tion in the 3 h postischemic cortex (Fig. 3A) despite the finding that mRNA coding for these proteins is preserved (Dienel et al. 1986).…”

Induction of 70-kDa Heat Shock Protein and hsp70 mRNA following Transient Focal Cerebral Ischemia in the Rat

“…Neurons are the cells most vulnerable to ischemia, glia are more resistant to ischemia, and endothelial cells are the most resistant cell type in brain to ischemia. We hypothesized that when ischemia is sufficiently long to produce infarction, transcription and/or transla tion of the heat shock genes (Dienel et al , 1986;Kies sling et al , 1986;Thilmann et al , 1986) is pre vented in neurons and glia. Indeed, in situ hybrid ization showed much less hsp70 mRNA signal in lateral striatum than in cortex; this could be caused by the loss of the transcriptional ability of neurons and glia.…”

Localization of 70 kDa Stress Protein mRNA Induction in Gerbil Brain after Ischemia

“…Cerebral ischemia leads to induction of the 70 kDa stress/heat shock protein, hsp70, as well as other proteins characteristic of the stress response (Nowak, 1985;Dienel et al, 1986;Jacewicz et al, 1986;Kiessling et al, 1986;Dwyer et al, 1989;Gonzalez et al, 1989;Magnusson and Wieloch, 1989;Nowak et al, 1990a). Immunoreactive hsp70 is selectively localized in neurons, most strikingly in hippocampus, although its accumulation is mini mal in the CAl pyramidal cells vulnerable to isch emic injury (Vass et al, 1988;Nowak, 1989).…”