The effect of the rate of heat storage on serum heat shock protein 72 in humans

Hsp72 concentration has been shown to be higher in the serum (eHsp72) of runners with symptoms of heat illness than in non-ill runners. Recently, it has been suggested that the rate of heat storage during exercise in the heat may be an important factor in the development of heat stroke. Therefore, we compared the effect of two rates of heat storage on eHsp72 concentration during exercise in which subjects reached the same final core temperature. We hypothesized that with a lower rate of heat storage the increase in eHsp72 would be attenuated compared to a higher rate of heat storage. Nine heat acclimated subjects performed two exercise trials in a counterbalanced order in the heat (42°C, 30% relative humidity). The trials consisted of walking on a treadmill (~50% VO ₂ peak) dressed in military summer fatigues until rectal temperature reached 38.5°C. A high rate of heat storage (HS, 1.04 ± 0.10 W m⁻² min⁻¹, mean ± SE) occurred when subjects walked without cooling. To produce a lower rate of heat storage (LS, 0.54 ± 0.09 W m⁻² min⁻¹) subjects walked while wearing a water-perfused cooling vest underneath clothing. eHsp72 increased pre- to post-exercise (P < 0.05) but there was no difference (P > 0.05) in eHSP between the two rates of heat storage (LS 1.25 ± 0.73 to 2.23 ± 0.70 ng ml⁻¹, HS 1.04 ± 0.57 to 2.02 ± 0.60 ng ml⁻¹). This result suggests that eHsp72 is a function of the core temperature attained rather than the rate of heat storage.     

Biological activity of truncated C-terminus human heat shock protein 72

Heat shock protein 72 (Hsp72), a canonical intracellular molecular chaperone, may also function as an extracellular danger signal for the innate immune system. To further delineate the biological role of Hsp72 in the innate immune system, we generated two truncated versions of the full length human Hsp72 (N-terminus Hsp72, amino acids 1-430; and C-terminus Hsp72 amino acids 420-641) and directly compared their ability to activate cells from the macrophage/monocyte lineage. In RAW 264.7 macrophages transfected with a NF-κB-dependent luciferase reporter plasmid, C-terminus Hsp72 was a more potent inducer of NF-κB activity than N-terminus Hsp72, and this effect did not seem to be secondary to endotoxin contamination. C-terminus Hsp72-mediated activation of the NF-κB pathway was corroborated by increased activation of IκB kinase, degradation of IκBα, and increased NF-κB-DNA binding. C-terminus Hsp72 was a more potent inducer of tumor necrosis factor-α (TNFα) expression in RAW 264.7 macrophages and in primary murine peritoneal macrophages from wild-type mice. C-terminus Hsp72 did not induce TNFα expression in primary murine peritoneal macrophages from Toll-like receptor (TLR4) mutant mice, indicating a role for TLR4. In human THP-1 mononuclear cells, C-terminus Hsp72 induced tolerance to subsequent LPS stimulation, whereas N-terminus Hsp72 did not induce tolerance. Finally, control experiments using equimolar amounts of N-terminus or C-terminus Hsp72 demonstrated a higher biological potency for C-terminus Hsp72. These data demonstrate that the ability of human Hsp72 to serve as an activator for cells of the macrophage/monocyte lineage primarily lies in the C-terminus region spanning amino acids 420-641.     

Immunolocalisation of heat shock protein 72 and glycoprotein 96 in colonic adenocarcinoma

Heat shock protein 72 (HSP72) and glycoprotein 96 (gp96) are highly expressed in cancer tissues. Recent studies indicate the possible roles of HSP72 and gp96 in the development and progression of colonic carcinomas, but detailed information is still ambiguous. In this study, we investigated the correlation between clinical pathology and immunolocalisation of HSP72 and gp96 in human colonic carcinoma. The distribution of HSP72 and gp96 was studied in 160 human colonic carcinomas, with or without metastasis, as well as in mucous membranes adjacent to cancers by means of immunohistochemistry. HSP72 immunoreactivity was detected in 145 of 160 primary tumours (90.6%) and in 44 of 160 mucous membranes adjacent to cancers (27.5%). Gp96 was detected in 81.3% colonic carcinomas and in 13.8% mucous membranes adjacent to cancer. Immunolocalisation of HSP72 and gp96 was mainly cytoplasmic. HSP72 and gp96 immunolabelling was significantly higher in colonic carcinomas with metastasis than in those without metastasis (P<0.05). The results indicate a significant correlation between the immunopositivity of HSP72 and gp96 and the progression of colonic carcinomas. Immunolabelling of HSP72 and gp96 may be useful as diagnostic or prognostic markers in colonic carcinoma.     

Expression of heat shock protein 72 in atrophied rat skeletal muscles.

Changes in the expression of heat shock protein 72 (HSP72) in response to atrophic-inducing perturbations of muscle involving chronic mechanical unloading and denervation were determined. Adult male Wistar rats were assigned randomly to a sedentary cage control (CON), hind limb unloading (HU, via tail suspension), HU plus tenotomy (HU + TEN), HU plus denervation (HU + DEN), or HU + TEN + DEN group. Tenotomy and DEN involved cutting the Achilles tendon and removing a segment of the sciatic nerve, respectively. After 5 days, HSP72 levels in the soleus of the HU + DEN and HU + TEN + DEN groups were 42 (P < 0.05) and 53% (P < 0.01) less than CON, respectively. Soleus weight decreased in both groups. Heat shock protein 72 levels in the plantaris of the HU + TEN, HU + DEN, and HU + TEN + DEN groups were 31, 25, and 30% lower than CON, respectively (P < 0.05). Plantaris weight decreased in the HU + DEN and HU + TEN + DEN, but not in the HU + TEN group. Hind limb unloading alone had little effect on the HSP72 level in either muscle. Reduced levels of HSP72 were associated with a decreased soleus (r=0.62, P < 0.01) and plantaris (r=0.78, P < 0.001) weight. These results indicate that the levels of HSP72 in both a slow and a fast rat plantarflexor are responsive to a chronic decrease in the levels of loading and/or activation and suggest that the neuromuscular activity level and the presence of innervation of a muscle are important factors that induce HSP72 expression.     

Mycobacterial 65-kD heat shock protein induces release of proinflammatory cytokines from human monocytic cells.

Monocytes having phagocytosed mycobacteria are known to present the bacterial 65-kD heat shock protein (hsp) on their cell surface to alpha beta and gamma delta T lymphocytes. Cytotoxic CD4+ cells may then lyse monocytes expressing mycobacterial 65-kD hsp. However, it is not known whether 65-kD hsp directly stimulates monocyte functions other than antigen presentation. This study has demonstrated that following extraction of bacterial lipopolysaccharide, purified recombinant mycobacterial 65-kD hsp may directly activate THP-1 cells, a human monocytic line, to accumulate mRNA for and secrete tumour necrosis factor (TNF), a cytokine important in granuloma formation, the characteristic host immune response to mycobacterial infection. TNF gene expression and secretion following stimulation by hsp was dose-dependent and abolished by heat-induced proteolysis. Subsequently, THP-1 cells secreted IL-6 and IL-8, cytokines involved in recruitment and differentiation of T lymphocytes. The data indicate that secretion of proinflammatory cytokines from monocytes activated by mycobacterial 65-kD hsp may be important in the host immune response and in the development of antigen-specific T cell-mediated immunity.     

Immunohistochemical analysis of p53 protein and 72 kDa heat shock protein (HSP72) expression in ovarian carcinomas

Mutations of the tumour suppressor p53 gene have been reported in a variety of human malignant tumours, and are frequently associated with overexpression of p53 protein. To examine the significance of p53 gene alteration in malignant epithelial tumours of the ovary, we studied the immunohistochemical reactivity with a monoclonal antibody against p53 (PAb 1801) in 6 ovarian tumours of low malignant potential (LMP) and 32 ovarian carcinomas. The existence of any correlation of p53 overexpression with the clinicopathological features and with the immunohistochemical expression of 72 kDa heat shock protein (HSP72) and sex steroid receptors (oestrogen receptors; ER, progesterone receptors; PR) was also analysed. Expression of p53 was found in 2 of the 6 (33.3%) LMP tumours and in 15 of the 32 (46.9%) carcinomas. Strong expression of HSP72 was observed in 11 of the 17 (64.7%) p53-positive tumours, but only in 2 of the 21 (9.5%) p53-negative ones. Histologically, p53-positivity was observed in 7 of the 10 (70%) serous carcinomas, 4 of the 6 (66.7%) mucinous, 4 of the 10 (40%) endometrioid, and none of the 4 clear cell and 2 transitional cell carcinomas. Distribution of p53-positive cells in the tumour sections was homogenous in serous tumours, but heterogenous in mucinous lesions. All of the 4 carcinomas arising in endometriotic cysts were p53-negative. These differences support the thesis of heterogeneity in ovarian carcinogenesis. There was an inverse relationship between p53-positivity and sex steroid receptor status for ovarian carcinomas; 14 of the 15 p53-positive carcinomas were negative for both ER and PR, whereas 11 of the 17 p53-negative carcinomas were positive for ER and/or PR (P<0.01).     

Induction of heat shock protein 72 synthesis by endogenous tumor necrosis factor via enhancement of the heat shock element-binding activity of heat shock factor 1

Endogenous tumor necrosis factor (enTNF) acts as a resistance factor against cytotoxicity caused by heat by inducing manganous superoxide dismutase (MnSOD), thereby scavenging reactive oxygen free radicals. On the other hand, it is also well known that heat shock proteins (HSP) which are induced by heat stress behave as cytoprotective factor against this stress. However, the relationship of these two resistance factors is not elucidated yet. In the present study, we therefore proposed the possibility that enTNF enhances HSP72 expression. Heat-sensitive L-M (mouse tumorigenic fibroblast) cells, which normally do not express enTNF, were transfected with a nonsecretory-type human TNF-α expression vector to produce enTNF. Stable transfectants showed resistance to heat treatment and an increase of HSP72 expression. Conversely, when HeLa (human uterine cervical cancer) cells, which normally produce an appreciable amount of enTNF, were transfected with an antisense TNF-α mRNA expression vector to inhibit enTNF synthesis, their heat sensitivity was enhanced and HSP72 expression was reduced by half. Although enTNF caused no difference in the level of heat shock factor (HSF) 1 in these cells, enTNF expression correlated well with the binding activity of HSF-1 to a ³²P-labeled synthetic oligonucleotide containing the human heat shock element (HSE). These results indicate that enTNF participates not only in intrinsic resistance against heat via induction of MnSOD but also via enhancement of the HSE-binding activity of HSF 1 followed by augmentation of HSP72 expression.     

Exercise preconditioning reduces neuronal apoptosis in stroke by up-regulating heat shock protein-70 (heat shock protein-72) and extracellular-signal-regulated-kinase 1/2

Exercise preconditioning induces neuroprotection after stroke. We investigated the beneficial role of heat shock protein-70 (HSP-70) and phosphorylated extracellular-signal-regulated-kinase 1/2 (pERK 1/2), as they pertain to reducing apoptosis and their influence on Bcl-x_L, Bax, and apoptosis-inducing factor (AIF) in rats subjected to ischemia and reperfusion. Adult male Sprague–Dawley rats were subjected to 30 min of exercise on a treadmill for 1, 2, or 3 weeks. Stroke was induced by a 2-h middle cerebral artery (MCA) occlusion using an intraluminal filament. Protein levels of HSP-70, pERK 1/2, Bcl-x_L, Bax, and AIF were analyzed using Western blot. Neuroprotection was based on levels of apoptosis (TUNEL) and infarct volume (Nissl staining). Immunocytochemistry was used for cellular expression of HSP-70 and pERK 1/2. Significant (P<0.05) up-regulation of HSP-70 and pERK 1/2 after 3 weeks of exercise coincided with significant (P<0.05) reduction in neuronal apoptosis and brain infarct volume. Inhibition of either one of these two factors showed a significant (P<0.05) reversal in the neuroprotection. Bax and AIF were down-regulated, while levels of Bcl-x_L were up-regulated in response to stroke after exercise. Inhibiting HSP-70 or pERK 1/2 reversed this resultant increase or decrease. Our results indicate that exercise diminishes neuronal injury in stroke by up-regulating HSP-70 and ERK 1/2.     

The effect of acute hypoxia on heat shock protein 72 expression and oxidative stress in vivo

The inducible human stress protein HSP72 performs vital roles within the body at rest and during periods of stress. Recently, a previously disclosed quadratic trend in basal HSP72 expression was shown to be reliable and repeatable. The notion of a physiological stressor such as hypoxia disrupting this basal quadratic trend is an interesting one. Monocyte-expressed HSP72 and TBARS were determined every 3 h, over a 12-h period in 12 healthy male subjects on two separate days, with trial day one ascertaining control values. A hypoxic intervention consisting of 75 min at a simulated altitude of 2,980 m, commencing and ceasing at 0930 and 1045, respectively, was incorporated on trail day 2. The hypoxic condition induced significantly (elevated) HSP72 values at 1100 (P = 0.002), 1400 (P < 0.001), 1700 (P = 0.034) and 2000 (P = 0.041) compared to control. Significant increases in plasma TBARS were seen in the hypoxic condition compared to control at 1100 (P = 0.006) and 1400 (P = 0.032). The results demonstrate that a 75-min bout of normobaric hypoxia is sufficient to induce significant increases in HSP72 expression, which disrupts the basal quadratic trend shown by others and here in the control condition. This increase may be linked to the observed changes in oxidative stress. These results may provide a tool for manipulating basal monocyte HSP72 expression within human heat acclimation exercise protocols.     

Increased expression of heat shock protein 72 protects renal proximal tubular cells from gentamicin-induced injury

The nephrotoxicity of gentamicin (GM) has been widely recognized. Heat shock protein 72 (HSP72) has been reported to be a cytoprotectant. However, its cytoprotective effect against GM induced kidney injury has not yet been studied. In this study, we investigated the cytoprotective effect of HSP72 on GM-induced nephrotoxicity in vitro. Human Kidney tubular cell line, HK-2 cells were divided into four groups: control group, GM group (cells incubated with GM only), heat shock (HS) group (cells incubated at 43 degrees C for 30 min), and GM plus HS group, respectively. Lactate dehydrogenase (LDH) release increased time-dependently from 24 hr to 96 hr compared to the data of cells treated with GM only. Results of NAG activities, superoxide dismutase (SOD) activities and malondialdehyde (MDA) content were similar to that of the LDH release. The amount of HSP72 positive cells increased significantly at 72 hr after cells were treated with GM only. Both HSP72 protein and gene expression increased significantly at 72 hr when cells were treated with GM. On the other hand, HS induced HSP72 expression markedly. Pretreatment of HS inhibited HK-2 cells from GM-induced injury. It could reduce LDH release and NAG activity. HS also increased SOD activity, and decreased MDA content when cells were damaged by GM. These findings suggested that HS may protect kidney cells from GM-induced injury. Pre-induction of HSP72 may provide therapeutic strategies for nephrotoxicity induced by GM.     

The heat shock protein inhibitor KNK437 induces neurite outgrowth in PC12 cells

The nervous system is highly sensitive to various environmental stresses, such as ischemia. Stress response mechanisms that result in neuroprotection, including the induction of heat shock proteins (HSP), are not well understood. We examined the effect of KNK437, a compound that inhibits the synthesis of inducible heat shock proteins, on neuronal differentiation in rat pheochromocytoma PC12 cells. KNK437 decreased the expression of HSP70, and induced the neurite outgrowth of PC12 cells in the absence of stress stimulation, although with lower efficacy than nerve growth factor (NGF). Neurite outgrowth stimulated by KNK437 and NGF was blocked by inhibitors of ERK mitogen-activated protein (MAP) kinase, p38 MAP kinase, and glycogen synthase kinase 3β signaling pathways. NGF, and not KNK437, induced acetylcholine esterase (AChE) activity, a functional differentiation marker, indicating that KNK437 utilizes a mechanism distinct from that of NGF. KNK437 enhanced the activity of low dose NGF treatment on neurite outgrowth induction and ERK phosphorylation in PC12 cells, a finding that identifies KNK437 as a possible nerve regeneration agent. This compound may be a useful tool for the investigation of neuronal differentiation and neuroprotection against environmental stress.     

Inhibition of NaCl-induced heat shock protein 72 expression renders MDCK cells susceptible to high urea concentrations

 Exposure of Madin-Darby canine kidney (MDCK) cells to elevated extracellular NaCl concentrations is associated with increased heat shock protein 72 (HSP72) expression and improved survival of these pretreated cells upon exposure to an additional 600 mM urea in the medium. To establish a causal relationship between HSP72 expression and cell protection against high urea concentrations, two approaches to inhibit NaCl-induced HSP72 synthesis prior to exposure to 600 mM urea were employed. First, the highly specific p38 kinase inhibitor SB203580 was added (100 μM) to the hypertonic medium (600 mosm/kg H₂O by NaCl addition, 2 days of exposure), which significantly reduced HSP72 mRNA abundance and HSP72 content. Survival of these cells after a 24-h urea treatment (600 mM) was markedly curtailed compared with appropriate controls. Second, a pcDNA3-based construct, containing 322 bases of the HSP72 open reading frame in antisense orientation and the geneticine resistance gene, was transfected into MDCK cells. Clones with strong inhibition of HSP72 synthesis and others which express the protein at normal levels (comparable to nontransfected MDCK cells) after heat shock treatment or hypertonic stress were established. When these transformants were subjected to hypertonic stress for 2 days prior to exposure to an additional 600 mM urea for 24 h, cell survival was significantly reduced in those clones in which HSP72 expression was strongly inhibited. These results provide further evidence for the protective function of HSP72 against high urea concentrations in renal epithelial cells. Received: 14 September 1998 / Received after revision and accepted: 16 November 1998     

Releasing signals, secretory pathways, and immune function of endogenous extracellular heat shock protein 72

Heat shock proteins (Hsp) were first characterized as intracellular proteins, which function to limit protein aggregation, facilitate protein refolding, and chaperone proteins. During times of cellular stress, intracellular Hsp levels increase to provide cellular protection. Recently, it has been recognized that Hsp, particularly Hsp72, are also found extracellularly (eHsp72), where they exhibit potent immunomodulatory effects on innate and acquired immunity. Circulating eHsp72 levels also greatly increase during times of stress (i.e., when an organism is exposed to a physical/psychological stressor or suffers from various pathological conditions). It has been proposed that elevated eHsp72 serves a protective role by facilitating immunological responses during times of increased risk of pathogenic challenge and/or tissue damage. This review focuses on the in vivo releasing signals and immunomodulatory function(s) of endogenous eHsp72. In addition, we present data that emphasize the importance of caution when conducting in vitro immunological tests of Hsp72 function.     

一氧化氮通过诱导热休克蛋白72的表达打开缺血预处理的第二保护窗

目的:观察在缺血预处理(IP)过程中, 抑制一氧化氮(NO)的合成对热休克蛋白72(HSP72)表达的影响及对缺血预处理第二保护窗的减少心肌梗死面积的影响。方法:阻断兔冠状动脉5min, 再灌注10min, 重复4次, 完成IP。在IP前5min, 静脉注射NO合酶抑制剂N^G-硝基-L-精氨酸甲基酯(L-NAME), 并持续静脉注射至整个IP过程。IP后24h, 兔心脏或被快速取出测定HSP72的表达, 或阻断冠状动脉30min, 再灌注120min, 测定心肌梗死面积。结果:IP或假手术对照24h后, 各组之间心率和平均动脉压无明显差异。免疫印迹法显示IP组HSP72蛋白表达明显高于对照组, 而NO合酶抑制剂L-NAME阻断了这种IP诱导的HSP72的表达。IP组心梗面积明显低于对照组(29.8%±3.7%vs50.8%±4.3%, P＜0.01)。经L-NAME治疗阻断了IP的缩减心梗面积的作用(46.0±5.1%)。同时静脉注射L-精氨酸, 抵消了L-NAME对IP诱导HSP72表达和心梗面积的影响(33.5%±4.0%)。静脉注射NO供体(S-亚硝基-N-乙酰青霉胺, SNAP)模仿IP, 24h后诱导了HSP72的表达, 减小了心梗面积(31.3%±5.7%, P＜0.01vscontrol)。结论:本研究提示NO可能参与了IP诱导HSP72的表达和打开IP的第二保护窗。     

Psychophysiological stress induces heat shock cognate protein 70 messenger RNA in the hippocampus of rats.

Psychophysiological stress has been shown to increase 70,000 mol. wt heat shock protein messenger RNAs with northern blotting in rats. However, its localization is unknown. With in situ hybridization, we tested our hypothesis that restraint water-immersion stress may induce heat shock cognate protein 70 messenger RNA expression simultaneously with some morphological changes selectively in the hippocampus of rats. Stress for 6 h significantly increased heat shock cognate protein 70 messenger RNAs in the hippocampus, with maximal intensity in the CA3 subfield of the Ammon's horn and to a lesser extent in CA2. Stress for 12 h significantly increased heat shock cognate protein 70 messenger RNAs in the whole hemisphere including the cerebral cortex, the thalamus, the hypothalamus, and the hippocampus with the highest density in CA3. Heat shock cognate protein 70 messenger RNA in rats with stress for 6 h followed by recovery for 6 h significantly increased at CA3 and CA2 compared with the controls or rats stressed for 6 h without recovery. No overt histological changes were detected in neuronal or glial cells in the slides of hematoxylin-eosin or Cresyl Violet staining. These results show that psychophysiological stress induces heat shock cognate protein 70 messenger RNA in the most stress-vulnerable brain structure, hippocampal CA3, probably for cytoprotection.     

热休克蛋白47和热休克蛋白60在小鼠胚胎器官形成过程中的表达

目的：研究小鼠胚胎器官形成过程中热休克蛋白47（Hsp47）和热休克蛋白60（Hsp60）的表达情况。方法：于GD11～GD18,取得小鼠胚胎脑、眼、心、肺、胃、肝、四肢,于GD13-GD18取得肾,利用RT-PCR方法半定量检测Hsp47和Hsp60在各器官的表达丰度。结果：Hsp47在GD11～GD12和GD18的脑、GD11～GD12和GD17～GD18的眼、GD11～GD12和GD16～GD18的肺、GD11-GD18的肝脏不表达,在其余时间和其余器官均有表达;Hsp60在CD11～GD18时段胚胎的脑、眼、心、肺、胃、肝、肾（GD13～GD18）、四肢中均有表达。结论：Hsp47和Hsp60在小鼠胚胎器官形成过程中有不同的表达丰度,其表达模式也不一致;Hsp47在小鼠胚胎发育过程中可能有重要功能,Hsp60则具有广泛表达的特点。     

Experimental pneumococcal meningitis causes central nervous system pathology without inducing the 72-kd heat shock protein.

We examined whether experimental pneumococcal meningitis induced the 72-kd heat shock protein (HSP72), a sensitive marker of neuronal stress in other models of central nervous system (CNS) injury. Brain injury was characterized by vasculitis, cerebritis, and abscess formation in the cortex of infected animals. The extent of these changes correlated with the size of the inoculum (P less than 0.003) and with pathophysiologic parameters of disease severity, i.e., cerebrospinal fluid (CSF) lactate (r = 0.61, P less than 0.0001) and CSF glucose concentrations (r = -0.55, P less than 0.0001). Despite the presence of numerous cortical regions having morphologic evidence of injury, HSP72 was not detected in most animals. When present, only rare neurons were HSP72 positive. Western blot analysis of brain samples confirmed the paucity of HSP72 induction. The lack of neuronal HSP72 expression in this model suggests that at least some of the events leading to neuronal injury in meningitis are unique, when compared with CNS diseases associated with HSP72 induction.     

大鼠热休克蛋白72基因真核表达载体构建及在COS7细胞中的表达

背景：体外克隆、表达热休克蛋白,尤其正常时少量或不表达,而应激时大量表达的热休克蛋白72对研究其缺血再灌注损伤中的作用尤为重要。 目的：构建热休克蛋白72基因真核表达载体并于COS7细胞内表达,为HSP72蛋白免疫调节功能的研究奠定基础。 方法：采用RT-PCR技术从BABL/C大鼠肝细胞中扩增出热休克蛋白72 cDNA,经限制性核酸内切酶消化后,插入真核表达载体pcDNA3.1(+)的相应酶切位点,并将重组质粒转染COS7细胞,进行基因表达鉴定。 结果与结论：重组质粒插入基因序列检测证实为热休克蛋白72 cDNA,并能在COS7细胞稳定表达。成功构建热休克蛋白72真核表达载体,并于COS7细胞中成功转录与表达。     

Hyperthermia induces gene expression of heat shock protein 70 and phosphorylation of mitogen activated protein kinases in the rat cerebellum

The highly polysialylated neural cell adhesion molecule (PSA-NCAM) is recognized as a marker of neurogenesis or neural plasticity in adult nervous system. PSA-NCAM expression was examined in the spinal cord of transgenic mice harboring a mutant Cu/Zn superoxide dismutase (SOD1) gene. Immunohistochemistry showed a progressive expression of PSA-NCAM in surviving motoneurons of spinal ventral horns from an early and presymptomatic stage (25 weeks) before significant loss of ventral horn neurons, while no detectable PSA-NCAM in the ventral horn of non-transgenic littermates during the ageing process. The present data suggest that a specific expression of PSA-NCAM may be involved in the survival of spinal motoneurons under pathological conditions such as amyotrophic lateral sclerosis.