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1.
J Prev Alzheimers Dis ; 10(4): 699-705, 2023.
Article in English | MEDLINE | ID: mdl-37874090

ABSTRACT

Alzheimer's disease is a neurodegenerative disorder which contributes to millions of cases of dementia worldwide. The dominant theoretical models of Alzheimer's disease propose that the brain passively succumbs to disruptions in proteostasis, neuronal dysfunction, inflammatory and other processes, ultimately leading to neurodegeneration and dementia. However, an emerging body of evidence suggests that the adult brain is endowed with endogenous mechanisms of resilience which may enable individuals to remain cognitively intact for years despite underlying pathology. In this brief review, we discuss evidence from basic neuroscience and clinical research which demonstrates the existence of endogenous molecular signaling pathways that can promote resilience to neurodegeneration. The p75 neurotrophin receptor provides one such pathway of resilience due to its role as a fundamental signaling switch which determines neuronal survival or degeneration. We highlight a series of preclinical studies targeting the p75 neurotrophin receptor in mouse models which demonstrate resilience to amyloid. We briefly discuss the design and goals of a recent clinical trial of p75 neurotrophin receptor modulation in patients with mild to moderate Alzheimer's disease. Unique challenges for developing therapeutics and biomarkers which are optimized for targeting and detecting endogenous mechanisms of resilience are also discussed. Altogether, this review motivates further trial work of therapeutics modulating the p75 neurotrophin receptor and other deep biology targets.


Subject(s)
Alzheimer Disease , Animals , Humans , Mice , Alzheimer Disease/drug therapy , Amyloid beta-Peptides/metabolism , Brain/metabolism , Receptor, Nerve Growth Factor/metabolism
3.
J Neurosci ; 21(14): 5130-8, 2001 Jul 15.
Article in English | MEDLINE | ID: mdl-11438588

ABSTRACT

Drosophila and leech models of nervous system development demonstrate that protein tyrosine phosphatase (PTP) receptors regulate developmental neurite outgrowth. Whether PTP receptors regulate neurite outgrowth in adult systems or in regenerative states remains unknown. The leukocyte common antigen-related (LAR) receptor is known to be present in rodent dorsal root ganglion (DRG) neurons; therefore, the well established model of postcrush sciatic nerve regeneration was used to test the hypothesis that LAR is required for neurite outgrowth in the adult mammalian nervous system. In uninjured sciatic nerves, no differences in nerve morphology and sensory function were detected between wild-type and LAR-deficient littermate transgenic mice. Sciatic nerve crush resulted in increased LAR protein expression in DRG neurons. In addition, nerve injury led to an increase in the proportion of LAR protein isoforms known to have increased binding affinity to neurite-promoting laminin-nidogen complexes. Two weeks after nerve crush, morphological analysis of distal nerve segments in LAR-deficient transgenic mice demonstrated significantly decreased densities of myelinated fibers, decreased axonal areas, and increased myelin/axon area ratios compared with littermate controls. Electron microscopy analysis revealed a significant twofold reduction in the density of regenerating unmyelinated fibers in LAR-/- nerves distal to the crush site. Sensory testing at the 2 week time point revealed a corresponding 3 mm lag in the proximal-to-distal progression of functioning sensory fibers along the distal nerve segment. These studies introduce PTP receptors as a major new gene family regulating regenerative neurite outgrowth in vivo in the adult mammalian system.


Subject(s)
Nerve Regeneration , Nerve Tissue Proteins , Neurites/metabolism , Protein Tyrosine Phosphatases , Receptors, Cell Surface/metabolism , Sciatic Neuropathy/metabolism , Animals , Axons/pathology , Axons/ultrastructure , Disease Models, Animal , Ganglia, Spinal/metabolism , Ganglia, Spinal/pathology , Genes, Reporter , Homozygote , Laminin/metabolism , Macromolecular Substances , Membrane Glycoproteins/metabolism , Mice , Mice, Transgenic , Nerve Crush , Nerve Fibers/pathology , Nerve Fibers/ultrastructure , Nerve Regeneration/physiology , Neurites/ultrastructure , Neurons/metabolism , Neurons/pathology , Neurons/ultrastructure , Pain Measurement , Protein Isoforms/deficiency , Protein Isoforms/genetics , Protein Isoforms/metabolism , Receptor-Like Protein Tyrosine Phosphatases, Class 2 , Receptors, Cell Surface/deficiency , Receptors, Cell Surface/genetics , Sciatic Nerve/pathology , Sciatic Nerve/physiopathology , Sciatic Nerve/ultrastructure , Sciatic Neuropathy/pathology , Sciatic Neuropathy/physiopathology
4.
Carcinogenesis ; 21(2): 125-31, 2000 Feb.
Article in English | MEDLINE | ID: mdl-10657947

ABSTRACT

Regulation of cell proliferation by protein tyrosine phosphatases (PTPs) suggests that PTPs are important tumor suppressor genes. The gene encoding the leukocyte common-antigen-related (LAR) PTP receptor maps to chromosome 1p32-33, a region in which loss of heterozygosity is associated with human pheochromocytoma and other neuroectodermal tumors. The rat pheochromocytoma PC12 cell line was originally derived from the transplantable P259 tumor originating from the New England Deaconess Hospital (NEDH) line of Wistar inbred rats. Compared with their Wistar counterparts, 1-2-year-old NEDH rats exhibit a high incidence of spontaneous pheochromocytomas. This study investigates whether levels of LAR transcripts and protein are altered in NEDH adrenal tissue prior to tumor onset. In addition, alternative splicing of an LAR extracellular domain [LAR alternatively spliced element-c (LASE-c)], regulating LAR interaction with extracellular matrix components, was examined. These changes in LAR expression and alternative splicing were hypothesized to be more pronounced in tumor tissue and PC12 cells. Northern blot analysis demonstrated the presence of the approximately 5 kb LAR transcript in all cell lines examined, except PC12. In adrenal medulla tissue harvested from 2-3-month-old rats, LAR approximately 8 and approximately 5 kb transcript expression was decreased in NEDH compared with Wistar samples. RT-PCR demonstrated increased splicing of the LASE-c 27 bp alternatively spliced insert in the LAR extracellular domain in NEDH adrenal medulla tissue. Even greater LASE-c splicing was detected in adrenal medulla tumor tissue derived from 12-month-old NEDH rats and in PC12 cells. Western blot analysis demonstrated decreased levels of LAR protein and increased levels of LASE-c containing LAR protein isoforms in NEDH adrenal medulla tissue. These studies demonstrate that patterns of altered LAR expression present in PC12 cells and in pheochromocytoma tumor tissue are also present in adrenal tissue predisposed to a high incidence of spontaneous pheochromocytoma.


Subject(s)
Adrenal Gland Neoplasms/genetics , Cell Transformation, Neoplastic/genetics , Neoplasm Proteins/genetics , Nerve Tissue Proteins , Pheochromocytoma/genetics , Protein Isoforms/genetics , Protein Tyrosine Phosphatases , RNA, Messenger/biosynthesis , Rats, Wistar/genetics , Receptors, Cell Surface/genetics , Adrenal Cortex/enzymology , Adrenal Gland Neoplasms/enzymology , Adrenal Gland Neoplasms/pathology , Adrenal Medulla/enzymology , Alternative Splicing , Animals , Enzyme Induction , Female , Genetic Predisposition to Disease , Humans , Male , Neoplasm Proteins/biosynthesis , Neoplastic Syndromes, Hereditary/enzymology , Neoplastic Syndromes, Hereditary/genetics , PC12 Cells , Pheochromocytoma/enzymology , Pheochromocytoma/pathology , Protein Isoforms/biosynthesis , Rats , Receptor-Like Protein Tyrosine Phosphatases, Class 2 , Receptors, Cell Surface/biosynthesis , Reverse Transcriptase Polymerase Chain Reaction , Species Specificity
5.
Mol Carcinog ; 25(2): 139-49, 1999 Jun.
Article in English | MEDLINE | ID: mdl-10365916

ABSTRACT

The findings that protein tyrosine phosphatases (PTPs) regulate cell proliferation, response to growth factors, and cellular adhesion and the discovery that mutations in PTP genes are associated with breast cancer suggest that altered expression of PTPs contributes to the breast cancer cell phenotype. The leukocyte common antigen-related (LAR) PTP receptor is a prototype member of the class of PTP receptors containing cell adhesion domains. Full-length constitutively spliced LAR transcripts are expressed in breast and other tissues, whereas alternatively spliced isoforms are preferentially expressed in the nervous system. As a first step in evaluating the hypothesis that LAR-type PTPs influence breast cancer cell behavior, LAR expression and neuronal-type alternative splicing were examined in normal and breast cancer cell lines and tissues. Northern blot analysis demonstrated markedly increased LAR mRNA levels in breast cancer cell lines and tissues. Western blot analysis showed a greater than tenfold increase in LAR protein levels in breast cancer tissues. Reverse transcription-polymerase chain reaction was used to assess alternative splicing of extracellular and proximal membrane exons. Differential patterns of extracellular alternative splicing were found in normal versus carcinoma cell lines and tissues. Western blot analysis demonstrated increased levels of LAR protein isoforms encoded by alternatively spliced transcripts in breast cancer cell lines. This study is the first demonstration of increased LAR mRNA and LAR protein expression in breast cancer tissue and nontransformed cell lines and helps to elucidate the role of LAR in human breast cancer. The differential patterns of alternative splicing of LAR transcripts introduce LAR isoforms as candidate markers for future studies correlating differential gene expression and tumor behavior.


Subject(s)
Alternative Splicing , Breast Neoplasms/genetics , Nerve Tissue Proteins , Neurons/pathology , Protein Tyrosine Phosphatases , Receptors, Cell Surface/genetics , Breast/metabolism , Breast Neoplasms/pathology , Cell Line , Humans , Protein Isoforms/genetics , RNA, Messenger/genetics , RNA, Messenger/metabolism , Receptor-Like Protein Tyrosine Phosphatases, Class 2 , Tumor Cells, Cultured
7.
J Neurosci Res ; 47(3): 348-60, 1997 Feb 01.
Article in English | MEDLINE | ID: mdl-9039657

ABSTRACT

A role in neural development for protein tyrosine phosphatase (PTPase) receptors has been suggested by the finding of aberrant neurite outgrowth in Drosophila mutants lacking functional leukocyte common antigen-related (LAR) PTPase receptors; however, PTPase functions in the mammalian nervous system remain to be established. In transgenic mice containing a gene trap in the LAR gene, only trace expression of full-length LAR transcripts was found. In these mice, the size of basal forebrain cholinergic neurons was significantly reduced and cholinergic innervation of the dentate gyrus was markedly decreased. These findings constitute the first demonstration of an aberrant neuronal phenotype in a mammalian PTPase mutant and support the hypothesis that LAR-type PTPase receptors function to establish and/or maintain neuronal networks.


Subject(s)
Dentate Gyrus/cytology , Neurons/physiology , Protein Tyrosine Phosphatases/genetics , Acetylcholine/physiology , Animals , Benzoxazines , Biomarkers , Blotting, Northern , Cell Size/physiology , Choline O-Acetyltransferase/metabolism , Cholinergic Fibers/chemistry , Cholinergic Fibers/enzymology , Coloring Agents , Dentate Gyrus/chemistry , Female , Gene Expression/physiology , Genotype , Male , Mice , Mice, Transgenic , Molecular Sequence Data , Neurons/chemistry , Neurons/cytology , Oxazines , Phenotype , Prosencephalon/cytology , Protein Tyrosine Phosphatases/metabolism , RNA, Messenger/analysis , Receptor-Like Protein Tyrosine Phosphatases, Class 4 , Receptors, Cell Surface/genetics , Receptors, Nerve Growth Factor/analysis
8.
J Neurosurg ; 85(5): 892-900, 1996 Nov.
Article in English | MEDLINE | ID: mdl-8893729

ABSTRACT

Induction of the hemeoxygenase-1 (ho-1) stress gene is of importance for rapid heme metabolism and protection against oxidative injury in vitro and in vivo. Although ho-1 expression is observed in glia following exposure to whole blood and oxyhemoglobin, expression is mild, and other stress genes are not induced simultaneously in this setting. Hemeoxygenase-1 can be induced by several other physiological stresses in addition to heme. In the brain, ho-1 induction has been observed in the penumbra following focal cerebral ischemia. Because lysed blood is a spasmogen, the authors studied focal hyperexpression of the ho-1 gene after injection of lysed blood, whole blood, or saline into the cisterna magna of adult rats. Immunocytochemical analysis of HO-1 was performed at 1, 2, 3, and 4 days after the injections. Because the 70-kD inducible heat shock protein (HSP70) is induced by cellular stress, alternate sections were immunostained for HSP70 to assess whether focal hyperexpression was a stress phenomenon. An oligonucleotide probe was also used for in situ hybridization to demonstrate that ho-1 messenger (m)RNA was present. Focal HO-1 immunostained areas were observed after lysed blood injection only and were located mainly in the basal cortex and cerebellar hemisphere, although focal hyperexpression was also found in many other regions. The intensity of staining and the number of regions were maximum at 1 day. Double-labeled immunofluorescence revealed that many HO-1-immunoreactive cells were microglia. The HSP70 immunostaining of adjacent sections from the same animals demonstrated focal regions of immunoreactivity whose topography corresponded exactly with the topography of the HO-1-immunostained areas. Conventional histology in regions of HO-1 hyperexpression was often normal. In situ hybridization using the same oligonucleotide demonstrated that ho-1 mRNA was induced in focal areas of forebrain and in large regions of cerebellum within 6 hours of injection. These results demonstrate that focal hyperexpression of the ho-1 stress gene occurs after lysed blood injection and appears to be an indicator of cellular stress and injury in regions in which infarction does not occur. These results also suggest that cellular injury that occurs after injection of lysed blood may go undetected using conventional histology. Although direct heme metabolism was not investigated, our results indicate that rapid metabolism of heme, both intracellular and extracellular, may prove to be beneficial after subarachnoid hemorrhage.


Subject(s)
Brain/metabolism , HSP70 Heat-Shock Proteins/metabolism , Heme Oxygenase (Decyclizing)/metabolism , Subarachnoid Hemorrhage/metabolism , Animals , Disease Models, Animal , Female , Immunohistochemistry , In Situ Hybridization , Oxidative Stress , Rats , Rats, Sprague-Dawley
9.
Brain Res Mol Brain Res ; 42(1): 79-88, 1996 Nov.
Article in English | MEDLINE | ID: mdl-8915583

ABSTRACT

Using in situ hybridization, Northern blotting and RT-PCR we studied the post-ischemic expression of bcl-2, bcl-x, bax and ICE. One day following 5 min or 10 min of global ischemia bcl-2 and bcl-x mRNAs were induced in CA1 hippocampal pyramidal neurons while bax was unchanged. By 72 h after ischemia the expression of bcl-2, bcl-x and bax mRNAs decreased in CA1. The large isoform of bcl-x (bcl-xL), detected using RT-PCR, decreased in whole hippocampus by 24-72 h after ischemia relative to the putative short (bcl-xS) and transmembrane deleted (bcl-x delta TM) forms. Oligonucleotides to interleukin-1 beta convertase (ICE), which detected the expected 2-kb transcript and two lesser 1.5- and 3-kb hybridizing species, demonstrated slight mRNA induction in the CA1 region at 72 h following ischemia. DNA nick end-labeling at 3 days following ischemia showed DNA fragmentation in neurons limited to the CA1 region of hippocampus following 5 min ischemia, while DNA fragmentation was detected in CA1, CA3, dentate gyrus and cortical neurons following 10 min ischemia. The data support the view that hippocampal neurons might undergo an apoptosis-like death after global ischemia. Since global ischemia decreases total protein synthesis especially in the CA1 region, the increases in bcl-2 mRNA levels may not necessarily lead to increased Bcl-2 protein levels. This may explain why the CA1 neurons die despite the prominent induction of the protective bcl-2 gene. The observed decrease by 24 h in the bcl-xL/bcl-xS ratio which preceded DNA fragmentation may participate in the cell death produced by ischemia. However, because of the ischemia-induced decrease in total protein synthesis, the decreased bcl-xL/bcl-xS ratio does not necessarily lead to a changed ratio in the amount of the appropriate proteins. Since ICE-like mRNA was induced at 72 h when the CA1 neurons were dead, the significance of this ICE-like mRNA induction remains unclear.


Subject(s)
Apoptosis/genetics , Brain Ischemia/metabolism , Gene Expression Regulation/physiology , Hippocampus/metabolism , Animals , Blotting, Northern , Brain Ischemia/pathology , Caspase 1 , Cysteine Endopeptidases/genetics , DNA Fragmentation , Genes, bcl-2 , Gerbillinae , Hippocampus/blood supply , In Situ Hybridization , Male , Molecular Sequence Data , Polymerase Chain Reaction/methods , Pyramidal Cells/metabolism , Transcription, Genetic
10.
Heart Lung ; 25(3): 172-81, 1996.
Article in English | MEDLINE | ID: mdl-8635918

ABSTRACT

OBJECTIVE: To determine the prevalence, type, severity, and natural evolution of cognitive impairments in survivors of sudden cardiac arrest over time and to assess the relation of selected clinical and psychologic variables to those outcomes. DESIGN: Longitudinal with repeated measures. Twenty-five consecutive patients underwent extensive neuropsychologic testing during hospitalization within 3 weeks of their initial cardiac arrest. Of these, 17 completed additional testing at 6 to 9 weeks, 12 to 15 weeks, and 22 to 25 weeks after the event. SETTING: Cardiac electrophysiologic services at a university teaching hospital, a community hospital, and home. OUTCOME VARIABLES: Orientation, attention, concentration, immediate recall, early retention, delayed recall, reasoning, motor speed, and motor regularity were measured. RESULTS: During hospitalization, 72% of the patients had mild to severe impairments in one or more cognitive areas. Memory, particularly delayed recall, was the most common deficit. At 6 months after the arrest event, 29% (5 of 17) of the patients continued to be impaired, and all had deficits in delayed recall. Depression was significantly related to deficits in attention and delayed recall at 6 months only. Time to postarrest awakening was the most reliable predictor of long-term cognitive functioning in this patient sample. CONCLUSION: A significant minority of sudden death survivors incur long-term cognitive impairments, particularly in delayed recall or short-term memory. The occurrence of long-term cognitive deficits in these patients can be estimated from the duration of unconsciousness after resuscitation (time-to-awakening).


Subject(s)
Cognition Disorders/etiology , Heart Arrest/complications , Adult , Female , Heart Arrest/psychology , Humans , Longitudinal Studies , Male , Memory Disorders/etiology , Mental Recall , Pilot Projects , Retention, Psychology , Survivors
11.
Brain Res Mol Brain Res ; 37(1-2): 201-8, 1996 Apr.
Article in English | MEDLINE | ID: mdl-8738152

ABSTRACT

The induction of the heme oxygenase-1 (HO-1) protein, also called HSP32, was compared to HSP70 heat shock protein induction following focal ischemia. Adult Sprague-Dawley male rats (n = 14) were subjected to either 30 min or 2 h of focal cerebral ischemia using the suture, middle-cerebral-artery (MCA) occlusion model. Controls (n = 4) had sham surgery. Following 24 h of reperfusion, subjects were killed and their brains stained immunocytochemically for HO-1 and the HSP70 heat shock proteins. One day following 30 min of ischemia, HO-1 and HSP70 staining in striatum occurred mainly in endothelial cells in infarcts and in glial cells surrounding the areas of infarction. Following the 30 min ischemia HO-1 was not induced in cortex whereas HSP70 was induced in cortical neurons in the MCA distribution. One day following 2 h of MCA ischemia, both HO-1 and HSP70 were induced in neurons in cortex in the MCA distribution. HO-1, however, was induced in glial cells throughout ipsilateral cortex, inside as well as outside the MCA distribution. This suggests that translation and/or transcription of the HO-1 and HSP70 genes are blocked in neurons and glia destined to die within infarcts, whereas translation of these stress genes continues in the endothelial cells. The duration of ischemia required to induce HSP70 in cortical neurons appears to be less than that required to induce HO-1 in cortical glia. Prolonged spreading depression and/or diffuse hemispheric ischemia may induce HO-1 in glia throughout the ipsilateral cortex via immediate early gene activation of the AP-1 site in the HO-1 promoter. Since HO-1 degrades heme, a pro-oxidant, to antioxidant molecules, the induction of HO-1 may augment oxidative defense mechanisms compromised by cerebral ischemia.


Subject(s)
Brain Ischemia/metabolism , Brain/metabolism , Heme Oxygenase (Decyclizing)/metabolism , Animals , HSP70 Heat-Shock Proteins/metabolism , Immunohistochemistry , Male , Rats , Rats, Sprague-Dawley
12.
Brain Res ; 713(1-2): 211-22, 1996 Mar 25.
Article in English | MEDLINE | ID: mdl-8724993

ABSTRACT

The heme released following subarachnoid hemorrhage is metabolized by heme-oxygenase (HO) to biliverdin and carbon monoxide (CO) with the release of iron. The HO reaction is important since heme may contribute to vasospasm and increase oxidative stress in cells. HO is comprised of at least two isozymes, HO-2 and HO-1. HO-1, also known as heat shock protein HSP32, is inducible by many factors including heme and heat shock. HO-2 does not respond to these stresses. To begin to examine HO activity following subarachnoid hemorrhage (SAH), the expression of HO-1 and HO-2 was investigated after experimental SAH in adult rats. Immunocytochemistry for HO-1, HO-2 and HSP70 proteins was performed at 1, 2, 3 and 4 days after injections of lysed blood, whole blood, oxyhemoglobin and saline into the cisterna magna. A large increase in HO-1 immunoreactivity was seen in cells throughout brain following injections of lysed blood, whole blood, and oxyhemoglobin but not saline. Lysed blood, whole blood and oxyhemoglobin induced HO-1 in all of the cortex, hippocampus, striatum, thalamus, forebrain white matter and in cerebellar cortex. HO-1 immunoreactivity was greatest in those regions adjacent to the basal subarachnoid cisterns where blood and oxyhemoglobin concentrations were likely highest. Double immunofluorescence studies showed the HO-1 positive cells to be predominately microglia, though HO-1 was induced in some astrocytes. HO-1 expression resolved by 48 h. HO-2 immunoreactivity was abundant but did not change following injections of blood. A generalized induction of HSP70 heat shock protein was not observed following injections of lysed blood, whole blood, oxyhemoglobin, or saline. These results suggest that HO-1 is induced in microglia throughout rat brain as a general, parenchymal response to the presence of oxyhemoglobin in the subarachnoid space and not as a stress response. This microglial HO-1 response could be protective against the lipid peroxidation and vasospasm induced by hemoglobin, by increasing heme clearance and iron sequestration, and enhancing the production of the antioxidant bilirubin.


Subject(s)
Brain/metabolism , Heme Oxygenase (Decyclizing)/biosynthesis , Neuroglia/metabolism , Subarachnoid Hemorrhage/metabolism , Animals , Antibodies/immunology , Disease Models, Animal , Female , Immunohistochemistry , Rats , Rats, Sprague-Dawley
13.
Cerebrovasc Brain Metab Rev ; 8(2): 95-158, 1996.
Article in English | MEDLINE | ID: mdl-8727184

ABSTRACT

Changes in gene expression in the brain in response to adverse conditions, such as ischemia or excitotoxin exposure, may be part of the injury process or represent an adaptive response which may be protective during subsequent stressful events. In this review we have considered the regulation, functions and potential relationships to the pathophysiology of ischemia of several major groups of stress-induced genes, including those of the M(r) 27,000, 32,000 (heme oxygenase), 70,000 and 90,000 heat shock protein families, the glucose-regulated proteins, glucose transporters and ubiquitin. Patterns of gene expression in several injury models, including focal and global ischemia, excitotoxin/ seizure-related injury and hyperthermia are reviewed. In vitro expression studies and the phenomenon of ischemic tolerance are also discussed. It is concluded that stress gene expression provides a useful marker of cellular injury, and that disjunction of mRNA and protein expression may be indicative of imminent death in cells which survive the initial insult. Though other stress proteins may play a role, it seems unlikely that neuronal hsp70 expression is a major contributor to ischemic tolerance.


Subject(s)
Brain Chemistry/genetics , Gene Expression Regulation/physiology , Stress, Physiological/genetics , Animals , Brain Ischemia/metabolism , Humans , Stress, Physiological/metabolism
14.
Restor Neurol Neurosci ; 9(4): 227-30, 1996 Jan 01.
Article in English | MEDLINE | ID: mdl-21551911

ABSTRACT

Numerous studies have demonstrated evidence of DNA nick end-labeling and DNA laddering following cerebral ischemia. To determine whether genes directly implicated in apoptosis were induced by ischemia, the expression of bcl-2, bcl-x and ICE mRNAs were examined using oligonucleotide probes. Northern blots demonstrated induction of bcl-2 mRNA and bcl-x mRNAs in hippocampus 24 and 72 h following 5 min of global ischemia. In situ hybridization demonstrated induction of bcl-2 and bcl-x mRNAs in CAl pyramidal neurons of hippocampus at 24 h following ischemia which decreased by 72 h. ICE-like mRNA was induced in non-neuronal cells in the CAl region at 72 h following global ischemia. The data show that genes implicated in either protecting against or promoting programmed cell death in other systems are induced following cerebral ischemia. It is hypochesized that CAl neuronal cell death could be accounted for by the failure of the ischemic cells to make protective proteins that protect the cells from an ischemic induced apoptotic-like cell death.

15.
J Neurosci Res ; 40(6): 807-19, 1995 Apr 15.
Article in English | MEDLINE | ID: mdl-7629893

ABSTRACT

Following metabolic stress a variety of gene products are induced in cells in the brain, some of which may protect the tissue from subsequent stresses. The heat shock proteins (hsps), in particular hsp70, have been widely studied in this context, but evidence for the involvement of known hsps in protection of the CNS is inconclusive. We have therefore undertaken the search for other stress-induced proteins which may mitigate ischemic injury. Beginning with degenerate RT-PCR, we have isolated a rat-brain cDNA encoding a protein highly similar to human grp75, a mitochondrial member of the hsp70-family of stress proteins. It is also highly similar to two non-mitochondrial proteins; mortalin, a senescence-related gene product, and pbp74, a protein implicated in B-cell peptide processing. Sequence structure and phylogenetic analyses predict mitochondrial localization and induction by a calcium ionophore and glucose deprivation in PC12 cells support its identification as rat grp75. In situ analysis of normal brain reveals an unusual distribution, with very high expression in neurons of the basal forebrain, reticular and subthalamic nuclei, globus pallidus, amygdala and elsewhere. grp75-mRNA is upregulated following focal brain ischemia in a distinctive fashion. When the degree of injury is small, induction occurs in the area of injury, similar to the pattern observed for hsp70. However, when the injury is extensive, hsr is upregulated in neurons outside the ischemic area. The induction of grp75 may represent a sensitive marker of metabolically compromised tissue.


Subject(s)
Brain Ischemia/metabolism , Brain/metabolism , Cloning, Molecular , HSP70 Heat-Shock Proteins/genetics , HSP70 Heat-Shock Proteins/metabolism , Membrane Proteins/genetics , Membrane Proteins/metabolism , Amino Acid Sequence , Animals , Base Sequence , Female , Molecular Probes/genetics , Molecular Sequence Data , Nerve Tissue Proteins/genetics , Nerve Tissue Proteins/metabolism , RNA, Messenger/metabolism , Rats , Rats, Sprague-Dawley , Reference Values , Tissue Distribution
16.
J Biol Chem ; 270(10): 5032-8, 1995 Mar 10.
Article in English | MEDLINE | ID: mdl-7890611

ABSTRACT

A monomeric rat beta-galactoside-binding lectin previously purified from extracts of rat lung has been localized to erythrocytes, and the cDNA encoding it has been isolated from a rat reticulocyte cDNA library. The deduced amino acid sequence of the cDNA predicts a protein with a M(r) of 16,199, with no evidence of a signal peptide. The deduced sequence is identical to the sequences of seven proteolytic peptides derived from the purified lectin. Peptide analysis by mass spectrometry indicates that the N-terminal methionine is cleaved and that serine 2 is acetylated. The lectin shares all the strictly conserved amino acid residues of other members of the mammalian galectin family and is designated galectin-5 (GenBank accession number L36862). Galectin-5 is a weak agglutinin of rat erythrocytes, despite its monomeric structure. The gene encoding galectin-5 (LGALS5) has been mapped in mouse to chromosome 11, approximately 50 centimorgans from the centromere and 1.8 +/- 1.8 centimorgans from the polymorphic marker D11Mit34n, a region syntenic with human chromosome 17q11.


Subject(s)
Erythrocytes/metabolism , Galectins , Lectins/biosynthesis , Lectins/chemistry , Lung/metabolism , Amino Acid Sequence , Animals , Base Sequence , Chromatography, Gel , Chromatography, High Pressure Liquid , Cloning, Molecular , DNA Primers , DNA, Complementary , Electrophoresis, Polyacrylamide Gel , Lectins/isolation & purification , Mammals , Molecular Sequence Data , Open Reading Frames , Peptide Fragments/chemistry , Peptide Fragments/isolation & purification , Polymerase Chain Reaction , Protein Conformation , Rats , Recombinant Proteins/biosynthesis , Recombinant Proteins/chemistry , Recombinant Proteins/isolation & purification , Restriction Mapping , Reticulocytes/metabolism , Sequence Homology, Amino Acid
17.
Neuroscience ; 62(4): 1079-92, 1994 Oct.
Article in English | MEDLINE | ID: mdl-7845588

ABSTRACT

Non-competitive N-methyl-D-aspartate receptor antagonists, including phencyclidine, ketamine, and MK801, produce vacuoles and induce the hsp 70 stress gene in layer III pyramidal neurons of the rat cingulate cortex. This study shows that phencyclidine (50 mg/kg) induces hsp 70 messenger RNA and HSP70 stress protein primarily in pyramidal neurons in posterior cingulate and retrosplenial cortex, neocortex, insular cortex, piriform cortex, hippocampus, and in the basal nuclei of the amygdala. Several neurotransmitter receptor antagonists inhibited induction of HSP70 produced by phencyclidine (50 mg/kg): haloperidol (ED50 = 0.8 mg/kg), clozapine (ED50 = 1 mg/kg), valium (ED50 = 1 mg/kg), SCH 23390 (ED50 = 7 mg/kg) and muscimol (ED50 = 3 mg/kg). Baclofen had no effect. Nifedipine blocked the induction of HSP70 produced by phencyclidine in some regions (cingulate, neocortex, insular cortex) but only partially blocked HSP70 induction in other regions (piriform cortex, amygdala). These results suggest that phencyclidine injuries pyramidal neurons via dopamine D1, D2, D4, sigma and other receptors. Several factors appear to contribute to this unusual multi-receptor mediated injury. (1) Phencyclidine blocks N-methyl-D-aspartate receptors on GABAergic interneurons resulting in decreased inhibition of pyramidal neurons. This may help to explain why multiple excitatory receptors mediate the injury and why GABAA agonists decrease the injury produced by phencyclidine. (2) Phencyclidine blockade of an amine transporter helps explain why dopamine receptor antagonists ameliorate injury. (3) Phencyclidine depolarizes neurons and produces high, potentially damaging intracellular calcium levels probably by blocking K+ channels that may be linked to sigma receptors. Since nifedipine prevents injury in cingulate, insula, and neocortex, it appears that calcium entry through L-type voltage gated calcium channels plays a role in the pyramidal neuronal injury produced by phencyclidine in these regions. There are similarities between the cingulate neurons injured by phencyclidine and circuits recently hypothesized to explain receptor changes in cingulate gyrus of schizophrenic patients. The present and previous studies also provide approaches for decreasing the clinical side effects of N-methyl-D-aspartate receptor antagonists to facilitate their possible use in the treatment of ischemia and other disorders.


Subject(s)
Calcium Channels/physiology , Gene Expression Regulation , HSP70 Heat-Shock Proteins/genetics , Ion Channel Gating , Phencyclidine/pharmacology , Pyramidal Cells/physiology , Receptors, Cell Surface/physiology , Animals , Electrophysiology , Female , HSP70 Heat-Shock Proteins/metabolism , Immunohistochemistry , RNA, Messenger/metabolism , Rats , Rats, Sprague-Dawley
18.
Psychopharmacol Bull ; 30(4): 555-60, 1994.
Article in English | MEDLINE | ID: mdl-7770620

ABSTRACT

Noncompetitive N-methyl-D-aspartate (NMDA) receptor antagonists, including ketamine, MK-801, and phencyclidine (PCP), induce the HSP70 heat shock or stress gene in pyramidal neurons in rat posterior cingulate and retrosplenial cortex. PCP also induces HSP70 in many other pyramidal neurons in brain including neocortex, insular cortex, piriform cortex, hippocampus, and basal nuclei of the amygdala. Several neurotransmitter antagonists, including haloperidol, clozapine, SCH-22390, diazepam, and muscimol, inhibited induction of HSP70 produced by PCP. Baclofen had no effect. Nifedipine blocked induction of HSP70 by PCP in cingulate, neocortex, and insular cortex but only partially blocked HSP70 in piriform cortex and amygdala. These data suggest that phencyclidine injures pyramidal neurons via dopamine D1, D2, D4, sigma, and other receptors. Gamma-aminobutyric acid (GABA) agonists ameliorate the injury. A model is proposed whereby NMDA receptor blockade on GABA neurons decreases inhibitory inputs onto cortical pyramidal neurons and makes them more vulnerable to injury from a variety of excitatory inputs. It is possible that psychosis produced by PCP and other NMDA antagonists correlates with overactivity and eventual injury to cingulate pyramidal neurons.


Subject(s)
Antipsychotic Agents/pharmacology , HSP70 Heat-Shock Proteins/biosynthesis , Neurons/drug effects , Receptors, N-Methyl-D-Aspartate/antagonists & inhibitors , Animals , Female , HSP70 Heat-Shock Proteins/analysis , Neurons/metabolism , Rats , Rats, Sprague-Dawley
19.
J Neurosci Res ; 36(3): 325-35, 1993 Oct 15.
Article in English | MEDLINE | ID: mdl-8271311

ABSTRACT

A reverse transcriptase-polymerase chain reaction (RT-PCR) product obtained from ischemic rat brain RNA was used to screen a rat ischemic forebrain cDNA library for a cDNA clone containing the entire open reading frame for the inducible hsp70. The coding sequence for the rat hsp70 cDNA demonstrated significant similarities with the human hsp70 of Hunt and Morimoto (Proc Natl Acad Sci 82:6455-6459, 1985) and the mouse hsp70 of Hunt and Calderwood (Gene 87:199-204, 1990). The rat inducible hsp70 and constitutive hsc73 sequences are distinct. There was a low level of hsp70 mRNA expression in normal rat brain as in found in other tissues. hsp70 mRNA was markedly induced in rat brain 8 hours following global ischemia and kainic acid-induced seizures. Northern blots showed a approximately 2.9kb hsp70 mRNA band from control, kainic acid, and ischemic brains. RT-PCR confirmed the presence of hsp70 mRNA in normal rat brain. Since there are at least five human and six mouse inducible hsp70 genes known, many other rat hsp70 genes probably exist that could function in different cells or organelles or be induced under different circumstances.


Subject(s)
Brain/metabolism , DNA, Complementary/genetics , Gene Expression , Heat-Shock Proteins/genetics , Ischemic Attack, Transient/genetics , Stress, Physiological/genetics , Animals , Base Sequence , Blotting, Northern , Brain Chemistry , Heat-Shock Proteins/chemistry , Humans , Ischemic Attack, Transient/metabolism , Kainic Acid , Molecular Sequence Data , Polymerase Chain Reaction , RNA, Messenger/analysis , RNA, Messenger/metabolism , Rats , Seizures/chemically induced , Seizures/genetics , Seizures/metabolism , Sequence Homology, Amino Acid
20.
Biochemistry ; 32(1): 260-7, 1993 Jan 12.
Article in English | MEDLINE | ID: mdl-8418845

ABSTRACT

The soluble mammalian lactose-binding lectins L-14-I and L-29 are both secreted and bind to oligosaccharides on laminin, a large extracellular matrix glycoprotein containing polylactosamine chains. Because of the potential functional significance of these lectin-laminin interactions, we compared quantitative aspects of L-14-I and L-29 binding to immobilized laminin using recombinant lectins labeled with 125I. We report that the concentration-dependent binding of L-29 exhibits positive cooperativity whereas binding of L-14-I does not. Cooperative binding of L-29 can also occur on glycoconjugate substrates other than laminin and is not dependent on cystine bond formation or aggregation in solution. L-29 contains repetitive sequences within the N-terminal domain not present in L-14-I. This domain is not required for binding activity, but is required for positive cooperativity. Though the precise mechanism of interaction of L-29 with laminin remains to be determined, it apparently results in assembly of a lectin aggregate on the substrate surface, which could have important functional consequences.


Subject(s)
Antigens, Differentiation/metabolism , Glycoconjugates/metabolism , Laminin/metabolism , Animals , Antigens, Differentiation/chemistry , Antigens, Differentiation/genetics , Base Sequence , Binding Sites , Collagenases/metabolism , Dithiothreitol/pharmacology , Escherichia coli/genetics , Galectin 3 , Iodine Radioisotopes , Lactose/metabolism , Mercaptoethanol/pharmacology , Molecular Sequence Data , Molecular Weight , Peptide Fragments/chemistry , Peptide Fragments/metabolism , Rats , Recombinant Proteins/metabolism , Repetitive Sequences, Nucleic Acid
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