Tomoko Kurata

Increased autophagy in transgenic mice with a G93A mutant SOD1 gene.

Autophagy, like the ubiquitin-proteasome system, is considered to play an important role in preventing the accumulation of abnormal proteins. Rat microtubule-associated protein 1 light chain 3 (LC3) is important for autophagy, and the conversion from LC3-I into LC3-II is accepted as a simple method for monitoring autophagy. We examined a SOD1G93A transgenic mouse model for amyotrophic lateral sclerosis (ALS) to consider a possible relationship between autophagy and ALS. In our study we analyzed LC3 and mammalian target of rapamycin (mTOR), a suppressor of autophagy, by immunoassays. The level of LC3-II, which is known to be correlated with the extent of autophagosome formation, was increased in SOD1G93A transgenic mice at symptomatic stage compared with non-transgenic or human wild-type SOD1 transgenic animals. Moreover, the ratio of phosphorylated mTOR/Ser2448 immunopositive motor neurons to total motor neurons was decreased in SOD1G93A-Tg mice. The present data show the possibility of increased autophagy in an animal model for ALS. And autophagy may be partially regulated by an mTOR signaling pathway in these animals.

Disruption of neurovascular unit prior to motor neuron degeneration in amyotrophic lateral sclerosis

Recent reports suggest that functional or structural defect of vascular components are implicated in amyotrophic lateral sclerosis (ALS) pathology. In the present study, we examined a possible change of the neurovascular unit consisting of endothelium (PCAM‐1), tight junction (occludin), and basement membrane (collagen IV) in relation to a possible activation of MMP‐9 in ALS patients and ALS model mice. We found that the damage in the neurovascular unit was more prominent in the outer side and preferentially in the anterior horn of ALS model mice. This damage occurred prior to motor neuron degeneration and was accompanied by MMP‐9 up‐regulation. We also found the dissociation between the PCAM‐1‐positive endothelium and GFAP‐positive astrocyte foot processes in both humans and the animal model of ALS. The present results indicate that perivascular damage precedes the sequential changes of the disease, which are held in common between humans and the animal model of ALS, suggesting that the neurovascular unit is a potential target for therapeutic intervention in ALS.

Atorvastatin and pitavastatin improve cognitive function and reduce senile plaque and phosphorylated tau in aged APP mice.

In addition to simply reducing the serum level of cholesterol, 3-hydroxy-3-methyl glutaryl coenzyme A (HMG-CoA) reductase inhibitors (statins) have various pleiotrophic effects such as reducing oxidative stress, neuroinflammation, and neurotoxicity. However, such a pleiotrophic effect has not been fully studied in a new statin (pitavastatin). We examined and compared the effects of two strong statins (atorvastatin, 30 mg/kg/day, p.o.; pitavastatin, 3mg/kg/day, p.o.) on the serum level of lipids, cognitive dysfunction, senile plaque (SP) and phosphorylated tau-positive dystrophic neuritis (pτDN) in amyloid precursor protein (APP) transgenic (Tg) mice from 5 months (M) of age to 20 M. These two statins improved behavioral memory and reduced the numbers of SP and pτDN at 15 and 20 M without affecting serum lipid levels, but preserved mice brain weight in pitavastatin group at 20 M. These protective effects of statins took 10 M from the beginning of treatment to show an improvement in the present model mice, and sensitivity to the statin treatment was linked to behavioral memory, SP and pτDN in this order. These findings suggest that early treatment with both atorvastatin and pitavastatin prevented subsequent worsening of cognitive function and the amyloidogenic process, probably due to pleiotrophic effects, suggesting a therapeutic potential for Alzheimers disease (AD).

Dynamic changes of mitochondrial fusion and fission proteins after transient cerebral ischemia in mice

With fusion or fission, mitochondria alter their morphology in response to various physiological and pathological stimuli, resulting in elongated, tubular, interconnected, or fragmented forms. Immunohistochemistry and Western blot analysis were performed at 2 days, 7 days, 14 days, and 28 days after 90 min of transient middle cerebral artery occlusion (tMCAO) in mice. This study showed that mitochondrial fission protein dynamin‐related protein 1 (Drp1) and fusion protein optic atrophy 1 (Opa1) were both upregulated in the ischemic penumbra, with the peak at 2 days after tMCAO, whereas phosphorylated‐Drp1 (P‐Drp1) progressively increased with a peak at 14 days after tMCAO. Double‐immunofluorescence analysis showed many Drp1/cytochrome c oxidase subunit l (COX1) double‐positive cells and Opa1/COX1 double‐positive cells in the ischemic penumbra and also showed some double‐positive cells with Drp1/terminal deoxynucleotidyl transferase‐mediated dUTP‐digoxigenin nick end labeling (TUNEL) and Opa1/TUNEL in the ischemic penumbra. In contrast, both Drp1 and Opa1 showed progressive decreases until 2 days after tMCAO in the ischemic core because of necrotic brain damage. The present study suggests that there was a continuous mitochondrial fission and fusion during these periods in the ischemic penumbra after tMCAO, probably in an effort toward mitophagy and cellular survival.

Therapeutic benefits of intrathecal protein therapy in a mouse model of amyotrophic lateral sclerosis

When fused with the protein transduction domain (PTD) derived from the human immunodeficiency virus TAT protein, proteins can cross the blood–brain barrier and cell membrane and transfer into several tissues, including the brain, making protein therapy feasible for various neurological disorders. We have constructed a powerful antiapoptotic modified Bcl‐XL protein (originally constructed from Bcl‐XL) fused with PTD derived from TAT (TAT‐modified Bcl‐XL), and, to examine its clinical effectiveness in a mouse model of familial amyotrophic lateral sclerosis (ALS), transgenic mice expressing human Cu/Zn superoxide dismutase (SOD1) bearing a G93A mutation were treated by intrathecal infusion of TAT‐modified Bcl‐XL. We demonstrate that intrathecally infused TAT‐fused protein was effectively transferred into spinal cord neurons, including motor neurons, and that intrathecal infusion of TAT‐modified Bcl‐XL delayed disease onset, prolonged survival, and improved motor performance. Histological studies show an attenuation of motor neuron loss and a decrease in the number of cleaved caspase 9‐, cleaved caspase 3‐, and terminal deoxynucleotidyl transferase‐mediated dUTP nick‐end labeling (TUNEL)‐positive cells in the lumbar cords of TAT‐modified Bcl‐XL‐treated G93A mice. Our results indicate that intrathecal protein therapy using a TAT‐fused protein is an effective clinical tool for the treatment of ALS.

Atorvastatin and pitavastatin reduce senile plaques and inflammatory responses in a mouse model of Alzheimer's disease.

Abstract Objectives: To examine and compare the pleiotropic anti-inflammatory effects and the long-term effects of atorvastatin and pitavasatin in mouse model of Alzheimer’s disease (AD). Methods: We examined the effects of two strong statins on senile plaque (SP) size and inflammatory responses in the brain of an amyloid precursor protein (APP) transgenic (Tg) mouse. We gave the Tg mice either atorvastatin or pitavastatin from 5–20 months of age, and performed immunohistological analysis [SP area, monocyte chemotactic protein 1 (MCP-1)-positive neurons, ionized calcium-binding adaptor molecule 1 (Iba-1)-1-positive microglia, and tumor necrosis factor &alpha ( (TNF-α)-positive neurons] every 5 months. Results: In the APP-Tg mice treated with both statins, the number of MCP-1-positive neurons was reduced at 10 months, that of Iba-1-positive microglia was reduced at 15 months, and that of TNF-α-positive neurons and the mean total SP area decreased at 15–20 months, compared with APP-Tg mice with vehicle treatment. Discussion: The protective effect of these statins took 5 months to reach significance in these mice, and the order of sensitivity to statin treatment was MCP-1>Iba-1>TNF-α>SPs. Proinflammatory responses including MCP-1, Iba-1, and TNF-α preceded and possibly contributed to SP formation. Pitavastatin has the same significant pleiotrophic effect to prevent and ameliorate inflammation and also has a long-term effect compared with atorvastatin, and both of them have high potential for a preventative approach in patients at risk of AD.

Early decrease of mitochondrial DNA repair enzymes in spinal motor neurons of presymptomatic transgenic mice carrying a mutant SOD1 gene

Growing evidence has recently shown that mutant SOD1 accumulate in the mitochondria and cause vacuolation in transgenic mice carrying mutant SOD1, an animal model of amyotrophic lateral sclerosis (ALS). In this study, the expressions of DNA repair enzymes, oxoguanine glycosylase 1 (ogg1), DNA polymerase beta (polbeta), and DNA polymerase gamma (polgamma) were examined in transgenic mice with an ALS-linked mutant SOD1 gene, a valuable model for human ALS. In presymptomatic Tg mice, the nuclear form of ogg1 was upregulated, whereas mitochondrial ogg1 remained at the same level. DNA polymerase was selectively downregulated in the mitochondria. This study suggests an impaired protective mechanism against oxidative stress in mitochondria. The expressions of these enzymes are predominant in spinal motor neurons, suggesting a mechanism of selective motor neuron death in this animal model of ALS.

Intrathecal injection of epidermal growth factor and fibroblast growth factor 2 promotes proliferation of neural precursor cells in the spinal cords of mice with mutant human SOD1 gene

We investigated three steps of neural precursor cell activation—proliferation, migration, and differentiation—in amyotrophic lateral sclerosis spinal cord treated with intrathecal infusion of epidermal growth factor (EGF) and fibroblast growth factor 2 (FGF2) into the lumbar spinal cord region of normal and symptomatic transgenic (Tg) mice with a mutant human Cu/Zn superoxide dismutase (SOD1) gene. We observed that 5‐bromodeoxyuridine (BrdU) + nestin double‐labeled neural precursor cells increased in the spinal cords of Tg mice compared with non‐Tg mice, with a much greater increase produced by EGF and FGF2 treatment. The number of BrdU + nestin double‐labeled cells was larger than that of BrdU + ionized calcium‐binding adapter molecule‐1 (Iba1), BrdU + glial fibrillary acidic protein (GFAP), or BrdU + highly polysialylated neural cell adhesion molecule (PSA‐NCAM) double‐labeled cells, but none expressed neuronal nuclear antigen (NeuN). On further analysis of the gray matter of Tg mice, the number of BrdU + nestin and BrdU + PSA‐NCAM double‐labeled cells increased more in the ventral horns than the dorsal horns, which was again greatly enhanced by EGF and FGF2 treatment. Because neural precursor cells reside close to the ependyma of central canal, the present study suggests that proliferation and migration of neural precursor cells to the ventral horns is greatly activated in symptomatic Tg mice and is further enhanced by EGF and FGF2 treatment and, furthermore, that the neural precursor cells preferentially differentiate into neuronal precursor cells instead of astrocytes in Tg mice with EGF and FGF2 treatment.

PINK1, a gene product of PARK6, accumulates in α-synucleinopathy brains

α-Synucleinopathy is an entity of neurodegenerative diseases such as Parkinson’s disease (PD), dementia with Lewy bodies (DLB) and multiple system atrophy (MSA), that involves accumulation of α-synuclein in the brain. PINK1 (PTEN induced kinase 1) is a novel gene recently identified as causative in autosomal recessive early onset parkinsonism (PARK6). In the present study, we examined the localisation of PINK1 in the brains of patients with α-synucleinopathy and found PINK1 in glial cytoplasmic inclusions (GCIs) in MSA, as well as in Lewy bodies (LBs) in PD and DLB. These findings imply that PINK1 may be involved in the formation of LBs and GCIs, suggesting that PINK1 is one of the major pathological proteins in α-synucleinopathy. The cDNA of PINK1, corresponding to 112–520 amino acids of the protein, was subcloned in a vector pET30(a) with a His tag. Anti-PINK1 antibody was generated against recombinant His tagged PINK1 by immunising a rabbit. The obtained antibody was affinity purified. A postmortem brain sample from a normal patient was homogenised, subjected to sodium dodecyl sulphate-polyacrylamide gel electrophoresis and transferred to a membrane. After blocking in Tris buffered saline with 5% dry milk, the membrane was incubated with anti-PINK1 antibody (1:1000). The membrane was then incubated with a secondary antibody (1:2500; Amersham, Buckinghamshire, UK), and visualised with an enhanced chemiluminescent substrate (Pierce, Rockford, Illinois, USA). Immunohistochemical analysis was carried out with paraffin embedded midbrain sections from patients with sporadic PD, …

Early and progressive impairment of spinal blood flow–glucose metabolism coupling in motor neuron degeneration of ALS model mice

The exact mechanism of selective motor neuron death in amyotrophic lateral sclerosis (ALS) remains still unclear. In the present study, we performed in vivo capillary imaging, directly measured spinal blood flow (SBF) and glucose metabolism, and analyzed whether if a possible flow—metabolism coupling is disturbed in motor neuron degeneration of ALS model mice. In vivo capillary imaging showed progressive decrease of capillary diameter, capillary density, and red blood cell speed during the disease course. Spinal blood flow was progressively decreased in the anterior gray matter (GM) from presymptomatic stage to 0.80-fold of wild-type (WT) mice, 0.61 at early-symptomatic, and 0.49 at end stage of the disease. Local spinal glucose utilization (LSGU) was transiently increased to 1.19-fold in anterior GM at presymptomatic stage, which in turn progressively decreased to 0.84 and 0.60 at early-symptomatic and end stage of the disease. The LSGU/SBF ratio representing flow—metabolism uncoupling (FMU) preceded the sequential pathological changes in the spinal cord of ALS mice and was preferentially found in the affected region of ALS. The present study suggests that this early and progressive FMU could profoundly involve in the whole disease process as a vascular factor of ALS pathology, and could also be a potential target for therapeutic intervention of ALS.