Yohtalou Tashima

Association of 72-kDa heat shock protein expression with adaptation to aspirin in rat gastric mucosa

It is well documented that gastric mucosa canincrease its resistance to mucosal damage caused byaspirin during repeated long-term administration ofaspirin. However, the underlying mechanism of thisadaptation is not well established. In the present study,we investigated the effect of long-term (chronic)administration of aspirin on expression of heat shockproteins (HSPs), which are known as endogenouscytoprotectants, in rat gastric mucosa. Rats were administeredaspirin (100 mg/kg) daily for up to 20 days. Aftervarious periods of aspirin administration, a high doseof aspirin (250 mg/kg) was administered, and the mucosal damage was assessed. Expression of heat shockproteins (HSPs) in gastric mucosa was evaluated byWestern blot. Intracellular localization of each HSP wasstudied immunohistochemically. ProstaglandinE2 (PGE2) and leukotriene B4(LTB4) levels were also investigated.Long-term aspirin administration resulted in developmentof resistance to aspirin-induced mucosal damage, and theincrease of HSP72 expression correlated with mucosal resistance to aspirin.No significant increase was observed in HSP60 and HSP90levels. Immunohistochemical study showed an increase ofHSP72 in the cytoplasm of mucosal surface cells. The PGE2 level was suppressed and nochange in the level of LTB4 was observed. Itis possible that HSP72 could play important roles ingastric mucosal adaptation when the PGE2level is suppressed by NSAIDs.

Differential Induction of HSP60 and HSP72 by Different Stress Situations in Rats (Correlation with Cerulein-Induced Pancreatitis)

We previously reported that water-immersionstress specifically induced the synthesis of a 60-kDaheat-shock protein (HSP60, chaperonin homolog) inpancreatic cells and preinduction of HSP60 completely prevented development of cerulein-inducedpancreatitis in the rat in an HSP60 quantitativelydependent manner. In order to study the cytoprotectivefunction of a 72-kDa heat-shock protein (HSP72,stress-inducible hsp70), the effect of specific preinduction ofHSP72 by hyperthermia on cerulein-induced pancreatitiswas investigated and compared with the effect ofpreinduction of HSP60 in this study. Expression of HSP60 and HSP72 in the pancreas wasinvestigated by immunoblot before and after waterimmersion or hyperthermia. Following pretreatment withwater-immersion stress or hyperthermia, the rats wereinjected with cerulein (40 μg/kg, intraperitoneally).The pancreas wet weight and serum amylase concentrationwere measured before and after cerulein injection.Hyperthermia (42.5°C, 20 min) specifically induced HSP72 in the pancreas. The synthesis of HSP60was specifically induced by water-immersion stress inthe pancreas. Cerulein-induced pancreatitis was clearlyprevented by specific preinduction of HSP60 by water-immersion stress. However, preinductionof HSP72 by hyperthermia had no preventive effect oncerulein-induced pancreatitis. Our findings suggest thatHSP60 and HSP72 have distinct functions in the pancreas, and their induction mechanisms arealso different in vivo. These results could be importantfor understanding the mechanism of “adaptivecytoprotection” in the pancreas mediated byheat-shock proteins.

Effect of preinduction of heat shock proteins on acetic acid-induced colitis in rats

In order to study the cytoprotective function ofheat shock proteins (HSPs) in vivo, the effect ofpreinduction of HSPs by hyperthermia on aceticacid-induced colitis was investigated. Expression of60-kDa, 72-kDa, and 90-kDa heat shock proteins (HSP60,HSP72, and HSP90, respectively) in rat colonic mucosawas investigated by Western blot analysis andimmunohistochemical study before and after hyperthermia. Following pretreatment with or withouthyperthermia, the rats received intrarectal infusion ofvarious doses of acetic acid. The colonic mucosal damagewas evaluated by macroscopic and microscopic assessments 24 hr after the intrarectal infusion of aceticacid. Expression of HSPs was significantly increased byhyperthermia in rat colonic mucosa. Immunohistochemicalstudy also showed the increments of HSPs in the colonic mucosal cells after hyperthermia.Acetic acid-induced colitis was dramatically preventedby pretreatment with hyperthermia when HSP72 and HSP90were preinduced. On the other hand, induction of HSP60 did not correlate with mucosalprotection. Our findings suggest that HSP72 and HSP90may have cytoprotective function against aceticacid-induced mucosal damage. These results may beimportant for understanding the mechanism of“adaptive cytoprotection” mediated byHSPs.

Induction of mitochondrial heat shock protein 60 and 10 mRNAs following transient focal cerebral ischemia in the rat

Heat shock proteins (HSPs) 60 and 10 are stress-inducible mitochondrial matrix proteins that form a chaperonin complex that is important for mitochondrial protein folding and function. The effect of cerebral ischemia on mitochondrial HSPs is unclear. The topographical and chronological patterns of HSP60 and HSP10 messenger ribonucleic acid (mRNA) expression and induction were investigated in the rat focal cerebral ischemia model. Focal cerebral ischemia was produced by transient middle cerebral artery occlusion for 30 or 90 min. Expression of mRNAs was analyzed using reverse transcription-polymerase chain reaction (RT-PCR) and in situ hybridization. RT-PCR analysis showed that both HSP60 and HSP10 mRNA levels increased significantly in the ischemic cortex from 4 to 24 h of reperfusion after 30 min of occlusion. In situ hybridization analysis demonstrated significant induction of both mRNAs in the whole ischemic cortex after 30 min of occlusion and in the dorsomedial border (penumbra) of the ischemic cortex and ipsilateral hippocampus after 90 min of occlusion. Expression patterns and the timing of the induction of both HSP60 and HSP10 mRNAs were identical throughout the experiments. Simultaneous induction of the mRNAs for the mitochondrial chaperonins, HSP60 and HSP10, in various regions in focal cerebral ischemia demonstrates that mitochondrial stress conditions persist concomitantly with cytosolic stress conditions in focal cerebral ischemia.

Induction of Heat-Shock Proteins HSP73 and HSP90 in Rat Kidneys After Ischemia

We examined rat kidneys for serial expressions of two major heat-shock proteins (HSPs), HSP73 and HSP90, after 60 min of unilateral renal ischemia up to day 28. Immunohistochemical studies showed that HSP73 and HSP90 were rapidly induced in the cytoplasm of injured epithelial cells of the S3 segment of proximal tubules and were again induced in the cytoplasm of regenerative cells in this segment from day 3. In epithelial cells of the Henles loops, HSP90 was also induced in the cytoplasm of both injured and regenerative cells, but HSP73 was not induced in this portion. Furthermore, a transient accumulation of HSP73 into the nucleus was observed in epithelial cells of papillary collecting ducts shortly after ischemia. Serial immunoblot analysis of isotonic buffer extractable fractions from ischemic kidneys revealed the induction of both HSP73 and HSP90 in the degenerative and regenerative phases: the maximal inductions in the two phases were at 3-6 and on days 5-7, respectively. These results demonstrate that HSP73 and HSP90 are induced in injured tubular epithelial cells with a regional heterogeneity during the degenerative and regenerative phases after renal ischemia and suggest that these HSPs are involved in the process of postischemic cellular recovery.

Induction and intracellular localization of a 72-kDa heat shock protein in rat gastric mucosa after water-immersion stress

We investigated the expression and changes in the intracellular localization of a 72-kDa heat shock protein (HSP72) in rat gastric pyloric and fundic mucosa before and after water-immersion stress. Severe mucosal damage was found in the fundic mucosal area of the stomach after this stress. However, no mucosal lesion developed in the pyloric mucosal area. HSP72 in both the soluble and insoluble fractions of the pyloric and the fundic mucosal areas was significantly increased after water-immersion stress, peaking 6 h after the initiation of the stress. The increase in HSP72 was more significant in the pyloric mucosal area than in the fundic mucosal area under both normal and stress conditions. The increase of HSP72 in the pyloric mucosal cells occurred prior to the formation of the mucosal lesions, whereas the increase of HSP72 in the fundic mucosal cells was observed after ulcer formation. An immunohistochemical study showed that HSP72 was constitutively expressed in the cytoplasm of the gastric mucosal cells, and that the intranuclear induction of HSP72 was remarkably intense in the pyloric mucosal cells, especially in the proliferative zone, compared with the fundic mucosal cells. Our results may suggest that HSP72 has an important cytoprotective function in gastric mucosal cells and that there is a “biophysical” difference between pyloric and the fundic mucosal cells.

Three-step purification method and characterization of the bovine brain 90-kDa heat shock protein.

A protein that cross-reacted with antibody against the 90-kDa heat shock protein (HSP90) of a mouse lymphoma cell line was purified from bovine brain by three steps. Fifty milligrams of the 90-kDa protein was recovered from 350 g of the brain cortex. The sedimentation coefficient and Stokes radius of the purified protein were 6.0 s and 6.7 nm, respectively. The molecular weight was calculated to be 170,000. The molecule was composed of two identical 90-kDa subunits. A partial amino acid sequence (23 residues) of this protein was homologous (96%) to human HSP90 (the sequence of 174-196). These facts led to the identification of the 90-kDa brain protein with HSP90. In bovine tissues, the brain contained this protein at a remarkably high concentration. The brain HSP90 was separable from glucocorticoid receptor by heparin-agarose and DNA-cellulose columns. It is concluded that HSP90 is present in brain cytosol and mostly as free molecules. Immunohistochemical studies showed that the protein was localized in nerve excitable cells. It was not found in nuclei but in cytosol.

Removal of protein interference in the Fiske-Subbarow method by sodium dodecyl sulfate.

Abstract In kinetic studies on erythrocyte membrane ATPase, the activity is assayed by following the release of orthophosphate from ATP by the Fiske-SubbaRow method. The deproteinization of the samples, which is essential before assay by this method, is an obstacle to the quick and efficient assay of large numbers of samples. Nonionic detergents, e.g., Lubrol, which are used in the purification of Na + -K + -ATPase from plasma membranes, also interfere strongly with the Fiske-SubbaRow method. It was found that the addition of sodium dodecyl sulfate to the samples before the orthophosphate assay solubilized much of the membrane protein, allowing orthophosphate to be determined by the Fiske-SubbaRow method without the deproteinization step. Sodium dodecyl sulfate and the solubilized proteins did not interfere with the determination. The addition of sodium dodecyl sulfate was also found to abolish the interference of nonionic detergents with the Fiske-SubbaRow determination. As a result, the assay of erythrocyte membrane ATPase could be greatly simplified.

Induction of a 72-kDa Heat Shock Protein and Cytoprotection Against Thioacetamide-Induced Liver Injury in Rats

Heat shock proteins are ubiquitous intracellularproteins induced by various physiological stress-relatedevents. A 72-kDa heat shock protein (HSP72) has beenreported to be an endogenous cytoprotectant in variety of cells in vitro . In order tostudy the cytoprotective function of HSP72 in the liver,the effect of preinduction of HSP72 in rat liver bysystemic hyperthermia on thioacetamide-induced hepatic injury was investigated in this study.Expression of HSP72 in the liver was investigated byimmunoblot and densitometric analysis. Rats wereinjected with thioacetamide (100 mg/kg, subcutaneously)with or without preinduction of HSP72 byhyperthermia. Serum AST and ALT concentrations weremeasured before and after thioacetamide injection inboth group. Histologic alteration of the liver wasevaluated also. Systemic hyperthermia (42.5°C, 20min) significantly induced HSP72 in the liver.Thioacetamide-induced hepatic injury was clearlyprevented by preinduction of HSP72 by hyperthermia.Prevention of hepatocyte damage was more clear in the areaaround central veins where HSP72 induction was apparent.Our findings might suggest that HSP72 has an importantfunction in the liver with respect to cytoprotection. These results might be important forunderstanding the mechanism of “adaptivecytoprotection” in the liver mediated by thefunction of heat shock proteins as “molecularchaperons” as reported in vitro.

Benign Prostatic Hypertrophy Affects the Endothelin Receptor Density in the Human Urinary Bladder and Prostate

The effects of benign prostatic hypertrophy (BPH) on the endothelin (ET) receptor density in the lower urinary tract tissues were studied using radioligand binding techniques. Saturation experiments revealed that there were significant amounts of the binding sites for the ET isoforms (ET-1, -2, -3) in the human bladder and prostate in both prostate hypertrophy (PH) and nonhypertrophy (NPH) patients. Autoradiograms of hypertrophic adenoma showed that ET-1 receptors were localized in both the stromal and glandular tissue. In the bladder and the prostate, the KD values were not significantly different between the PH and NPH groups. In the bladder dome, the Bmax values of 125I-ET-1, -2 and -3 decreased significantly in the PH groups, while, in the adenoma, they increased significantly in the PH group. BPH was found to affect the ET receptor density in both the bladder and the prostate. These data suggest that ETs are involved in the pathophysiology of BPH.