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Keiichi Higuchi

Publications and source records attributed to Keiichi Higuchi.

At least 19 recordsLinked to original sources
PubMed2006

Transmissibility of mouse AApoAII amyloid fibrils: inactivation by physical and chemical methods.

AApoAII amyloid fibrils have exhibited prion-like transmissibility in mouse senile amyloidosis. We have demonstrated that AApoAII is extremely active and can induce amyloidosis following doses less than 1 pg. We tested physical and chemical methods to disrupt AApoAII fibrils in vitro as determined by thioflavin T binding and electron microscopy (EM) as well as inactivating the transmissibility of AApoAII fibrils in vivo. Complete disruption of AApoAII fibrils was achieved by treatment with formic acid, 6 M guanidine hydrochloride, and autoclaving in an alkaline solution. Injection of these disrupted AApoAII fibrils did not induce amyloidosis in mice. Disaggregation with 6 M urea, autoclaving, and alkaline solution was incomplete, and injection of these AApoAII fibrils induced mild amyloidosis. Treatment with formalin, delipidation, freeze-thaw, and RNase did not have any major effect. A distinct correlation was obtained between the amounts of amyloid fibrils and the transmissibility of amyloid fibrils, thereby indicating the essential role of fibril conformation for transmission of amyloidosis. We also studied the inactivation of AApoAII fibrils by several organic compounds in vitro and in vivo. AApoAII amyloidosis provides a valuable system for studying factors that may prevent transmission of amyloid disease as well as potential novel therapies.

Amyloid↗
PubMed2006

Lanosterol synthase mutations cause cholesterol deficiency-associated cataracts in the Shumiya cataract rat.

The Shumiya cataract rat (SCR) is a hereditary cataractous strain. It is thought that the continuous occurrence of poorly differentiated epithelial cells at the bow area of the lens forms the pathophysiological basis for cataract formation in SCRs. In this study, we attempted to identify the genes associated with cataract formation in SCRs by positional cloning. Genetic linkage analysis revealed the presence of a major cataract locus on chromosome 20 as well as a locus on chromosome 15 that partially suppressed cataract onset. Hypomorphic mutations were identified in genes for lanosterol synthase (Lss) on chromosome 20 and farnesyl diphosphate farnesyl transferase 1 (Fdft1) on chromosome 15, both of which function in the cholesterol biosynthesis pathway. A null mutation for Lss was also identified. Cataract onset was associated with the specific combination of Lss and Fdft1 mutant alleles that decreased cholesterol levels in cataractous lenses to about 57% of normal. Thus, cholesterol insufficiency may underlie the deficient proliferation of lens epithelial cells in SCRs, which results in the loss of homeostatic epithelial cell control of the underlying fiber cells and eventually leads to cataractogenesis. These findings may have some relevance to other types of cataracts, inborn defects of cholesterol synthesis, and the effects of cholesterol-lowering medication.

Amino Acid Sequence↗
PubMed2006

Reduced coenzyme Q10 supplementation decelerates senescence in SAMP1 mice.

The SAMP1 strain is a mouse model for accelerated senescence and severe senile amyloidosis. We determined whether supplementation with coenzyme Q10 (CoQ10) could decelerate aging in SAMP1 mice and its potential role in aging. Plasma concentrations of CoQ10 and CoQ9 decreased with age in SAMP1 but not in SAMR1 mice. Supplementation with reduced CoQ10 (CoQH2, 250 mg/kg/day) for one week increased plasma CoQ10 concentrations, with an accompanying decrease in plasma CoQ9 concentrations. In two series of experiments, lifelong supplementation with CoQH2 decreased the senescence grading scores from 10 to 14 months, 7 to 15 months, and at 17 months of age. The body weight of female mice increased from 2 to 10 months of age versus controls in the second series of experiments. Lifelong CoQH2 supplementation did not prolong or shorten the lifespan, nor did it alter the murine senile amyloid (AApoAII) deposition rate or cancer incidence. In the second series of experiments, urinary levels of 8-hydroxydeoxyguanosine did not change with age or long-term supplementation with CoQH2. Urinary levels of acrolein (ACR)-lysine adduct increased significantly with age in SAMP1 mice; however, CoQH2 had no effect. Thus, lifelong dietary supplementation with CoQH2 decreased the degree of senescence in middle-aged SAMP1 mice.

Aging, Premature↗
PubMed2006

Secreted frizzled-related protein 4 is a negative regulator of peak BMD in SAMP6 mice.

UNLABELLED: We segregated a QTL for peak BMD on Chr 13 by generating congenic sublines of the senescence-accelerated mouse SAMP6. Sfrp 4 within this locus was responsible for lower BMD of SAMP6. INTRODUCTION: Our genome-wide linkage study using SAMP6 and SAMP2 showed a significant quantitative trait locus (QTL) for peak BMD on chromosome (Chr) 13. To verify the gene that regulates peak BMD, we generated a congenic strain, P6.P2-Pbd2(b), which carried a 15-cM SAMP2 interval on an osteoporotic SAMP6 background, and showed that this Pbd2 locus increased peak BMD in SAMP6. MATERIALS AND METHODS: To narrow down this interval, we generated a new congenic subline P6.P2-13. We studied the effect of this locus on morphological and histomorphological features in vivo and on osteoblasts in vitro. The levels of expression of all genes in the segregated interval were examined, and we clarified the effect of the candidate gene, secreted frizzled-related protein (Sfrp4), on osteoblasts in vitro. RESULTS: The new congenic strain, P6.P2-13, retained the 2.4-Mb SAMP2 interval on the SAMP6 background, and 11 genes existed in this interval. In morphometrical analysis, P6.P2-13 increased the bone area fraction (BA/TA) by 6.6% at the diaphysial cortex (p < 0.001) and increased the trabecular bone volume (BV/TV) by 54.2% at the distal metaphysis (p < 0.05) in the femora compared with those of SAMP6. The bone formation rate of P6.P2-13 was markedly increased at the periosteal surface of femoral cortex and that was caused by a higher proliferation rate of osteoblasts in P6.P2-13 compared with those in SAMP6. Quantitative RT-PCR analysis of calvaria tissue showed approximately 40-fold higher levels of expression of Sfrp4 in SAMP6 than in P6.P2-13. Taken together with the result that recombinant Sfrp4 suppressed the proliferation of osteoblasts, we hypothesized that Sfrp4 inhibited the proliferation of osteoblasts through its antagonistic effect on Wnt signaling. TCF/beta-catenin-dependent reporter activity in osteoblasts derived from SAMP6 showed lower responsiveness for the Wnt ligand, Wnt3A, than that in osteoblasts from P6.P2-13. CONCLUSIONS: In SAMP6 mice, Sfrp4 negatively regulates bone formation and decreases BMD through the inhibition of Wnt signaling.

3T3 Cells↗
PubMed2006

A third locus for Eosinophilia on chromosome 1 of the MES rats.

Matsumoto Eosinophilia Shinshu (MES) is a rat strain that spontaneously develops eosinophilia and eosinophil-related inflammatory lesions in many organs. In a previous study, we performed chromosomal mapping of the gene for eosinophilia in MES rats using backcross progeny and found that the major locus for eosinophilia was located on chromosome 19. In addition, another quantitative trait locus showing suggestive linkage for blood eosinophil count was found on chromosome 2. In this study, we examined additional marker loci in the backcross progeny and discovered that a third locus for eosinophilia was also located on chromosome 1. These data reinforce the notion that eosinophilia in MES rats is a rather complex genetic trait. However, these results will form the basis for identifying the candidate genes for eosinophilia.

Animals↗
PubMed2006

Transmission of amyloidosis in offspring of mice with AApoAII amyloidosis.

Pre-existing amyloid fibrils can induce further polymerization of endogenous precursor proteins in vivo. Thus, transmission of amyloid fibrils (AApoAII) may induce a conformational change in endogenous apolipoprotein A-II and accelerate amyloid deposition in mouse senile amyloidosis. To characterize transmissibility, we examined amyloidosis in the offspring of AApoAII-injected mother mice that possessed the amyloidogenic Apoa2(c) allele of the apolipoprotein A-II gene. At 4 months of age, amyloid deposits were detected in the intestines of offspring born from and nursed by amyloid fibril-injected mothers, with intensity of deposition increasing thereafter. No amyloid deposits were detected in the offspring of noninjected control mothers. Accelerated amyloidosis was also observed in offspring born from mothers without injection but nursed by amyloid fibril-injected mothers. However, this was not observed in offspring born from amyloid fibril-injected mothers but nursed by control mothers. This fostering excluded vertical transmission through the placenta, suggesting the presence of factors that accelerate amyloidosis during the nursing period. In addition, milk obtained from amyloid fibril-injected mothers induced AApoAII amyloidosis in young mice, and transmission electron microscopy detected noodle-like amyloid fibrils in milk of amyloid fibril-injected mothers. These results provide important insight into the etiology and pathogenesis of amyloid diseases.

Alleles↗
PubMed2005

A locus for eosinophilia in the MES rat is on Chromosome 19.

Matsumoto Eosinophilia Shinshu (MES) is a rat strain that spontaneously develops eosinophilia and eosinophil-related inflammatory lesions in many organs. We performed chromosomal mapping of the gene for eosinophilia by breeding backcross progeny. The onset of eosinophilia appeared to be delayed in the progeny compared with that in MES, with the prevalence of eosinophilia in the backcross progeny at 12 weeks of age being 22.5%. Genetic linkage analysis with marker loci indicated the major locus for eosinophilia was located at the end of the q arm region of Chromosome 19 (between D19Rat8 and telomere). The locus was denoted eosinophilia 1 (eos1). These data will form the basis for identification of the eos1 gene using a reverse genetic approach, which will hopefully lead to elucidation of the mechanisms involved in eosinophilia and eosinophilopoiesis.

Animals↗
PubMed2005

Unexpectedly high incidence of visceral AA-amyloidosis in slaughtered cattle in Japan.

Experimental mouse AA amyloidosis can be transmissible by dietary ingestion of amyloid fibrils and it is well known that AA amyloidosis occasionally develops in aged cattle. Bovine liver and intestine have conventionally been used in Oriental foods, and the incidence of visceral AA amyloidosis in slaughtered cattle was evaluated. Renal tissues from 302 aged cattle older than 4 years were obtained from a local abattoir. Amyloid deposition was microscopically examined and amyloid protein was immunochemically determined. Renal amyloid deposition was seen in 15 out of 302 cattle with no previous history of diseas, an incidence of 5.0%. Amyloid protein in these cattle was AA and they had pathological findings in their visceral organs on gross examination. The incidence of visceral AA amyloidosis in slaughtered cattle in this study was disturbingly high compared with those (0.4-2.7%) previously reported from Japan and other foreign countries. AA amyloidosis is a life-threatening complication in patients with chronic inflammatory diseases and these patients at risk should avoid ingesting food that may possibly contain AA amyloid fibrils. More detailed information on cattle amyloidosis is required to guarantee the safety of our food.

Amino Acid Sequence↗
PubMed2004

Induction of AApoAII amyloidosis by various heterogeneous amyloid fibrils.

Preformed amyloid fibrils accelerate conformational changes of amyloid precursor proteins and result in rapid extension of amyloid fibrils in vitro. We injected various kinds of amyloid fibrils into mice with amyloidogenic apoAII gene (Apoa2(C)). The most severe amyloid depositions were detected in the tissues of mice injected with mouse AApoAII(C) amyloid fibrils. Mild amyloid depositions were also detected in the tissues of mice that were injected with other types of fibrils, including synthetic peptides and recombinant proteins. However, no amyloid depositions were found in mice that were injected with non-amyloid fibril proteins. These results demonstrated that a common structure of amyloid fibrils could serve as a seed for amyloid fibril formation in vivo.

Amyloid↗
PubMed2004

Mouse testis transcriptome revealed using serial analysis of gene expression.

We applied serial analysis of gene expression (SAGE) to the mouse testis to reveal the global gene expression profile and to identify senescence-dependent changes in that profile. A total of 61,929 SAGE tags, including 19,323 unique tags, were obtained from 3- and 29-month-old BDF1 mice and 14-month-old SAMP1 mice. Genes highly expressed in the testis included those associated with spermatogenesis, protein metabolism, energy metabolism, growth and differentiation, and signal transduction. Testes from old mice of both strains appeared atrophied. Morphological examination of aged testes revealed extremely thin seminiferous epithelia and significantly decreased numbers of spermatids and spermatocytes. Despite the physical deterioration, no gross changes in the gene expression profile were apparent in the testes of old BDF1 mice. However, in 14-month-old SAMP1 mice, protamine 2 gene transcription was approximately 50% lower than in BDF1 mice. This reduction may be associated with the oligozoospermia and early decline in reproductive performance of SAMP1 mice. Our SAGE results are the first quantitative gene expression profile of the mouse testis and provide a reliable transcriptome reference for this organ.

Age Factors↗
PubMed2004

Tissue distribution, biochemical properties, and transmission of mouse type A AApoAII amyloid fibrils.

In mouse strains with the amyloidogenic apolipoprotein A-II (ApoA-II) gene (Apoa2c), the type C ApoA-II protein (APOAIIC) associates to form amyloid fibrils AApoAII(C) that lead to development of early onset and systemic amyloidosis with characteristic heavy amyloid deposits in the liver and spleen. We found age-associated heavy deposition of amyloid fibrils [AApoAII(A)] composed of type A ApoA-II protein (APOAIIA) in BDF1 and C57BL/6 mice reared at one of our institutes. AApoAII(A) fibrils were deposited in the intestine, lungs, tongue, and stomach but not in the liver or spleen. AApoAII(A) fibrils were isolated, and morphological, biochemical, and structural characteristics distinct from those seen in AApoAII(C) and mouse AA amyloid fibrils were found. Transmission electron and atomic force microscopy showed that the majority of isolated AApoAII(A) amyloid fibrils featured fine, protofibril-like shapes. AApoAII(A) fibrils have a much weaker affinity for thioflavine T than for AApoAII(C), whereas APOAIIA protein contains less of the beta-pleated sheet structure than does APOAIIC. The injection of AApoAII(A) fibrils induced amyloid deposition in C57BL/6 and DBA2 mice (Apoa2a) as well as in R1.P1-Apoa2c mice (Apoa2c), but AApoAII(A) induced more severe amyloidosis in Apoa2a strains than in the Apoa2c strain. It was found that AApoAII(A) fibrils isolated from mice with mildly amyloidogenic APOAIIA protein have distinct characteristics. Induction of amyloidosis by heterologous amyloid fibrils clearly showed interactions between amyloid protein monomers and fibrils having different primary structures.

Alleles↗
PubMed2004

Deposition of transthyretin amyloid is not accelerated by the same amyloid in vivo.

Acceleration of amyloid deposition by administration of amyloid fibrils and transmissibility of disease have been reported in several types of amyloidoses. Families with a variant transthyretin (TTR V30M)-associated familial amyloidotic polyneuropathy (FAP) exhibit genetic anticipation, with TTR V30M-amyloid depositing at an earlier age in successive generations. The molecular bases of anticipation in FAP have remained to be determined. We asked if administration of TTR-amyloid fibrils (ATTR) extracted from the heart of an FAP TTR V30M patient would accelerate ATTR deposition in transgenic mice expressing the human mutant ttr gene responsible for FAP TTR V30M and indeed the administration did accelerate deposition of apolipoprotein A-II-amyloid fibrils (AApoAII), and not A TTR. Our experiments present, for the first time, evidence that the degree of inducibility of ATTR is low relative to AApoAII and we suggest that administration of ATTR may not explain the genetic anticipation which occurs in FAP.

Amyloid↗
PubMed2003

Spontaneous hypomorphic mutations in antioxidant enzymes of mice.

An antioxidant enzymatic system is pivotal for aerobic animals to minimize the damage induced by reactive oxygen species. Spontaneous mutant animals with altered antioxidant enzyme activity should be useful for the study of the function of these enzymes in vivo. We examined the nucleotide sequences of the genes for the major antioxidant enzymes, including catalase (Cat), superoxide dismutase (Sod1, Sod2, Sod3), glutathione peroxidase (Gpx1, Gpx2, Gpx3, Gpx4, Gpx5), and glutathione reductase (Gsr) in 10 inbred mouse strains. Nonsynonymous nucleotide polymorphisms were identified in all genes, except for Gpx1, Gpx3, and Gpx4. Notably, the SJL/J mouse strain possessed unique nucleotide substitutions in the Gsr and Sod2 genes, which led to Asp39Ala and Val138Met amino acid substitutions in GSR and SOD2, respectively. The specific activity of GSR of SJL/J mice was reduced to 65% of that of NZB/N mice. In vivo activity, however, was higher in SJL/J, due to upregulated expression of the enzyme. The SOD2 activity in SJL/J mice was reduced to half that of other mouse strains. Consistent with this reduction, oxidative damage in the mitochondria was increased as demonstrated by a decrease of total glutathione and an increase in the levels of protein oxidation. These spontaneous hypomorphic alleles would be valuable in the study of free radical biology.

Animals↗
PubMed2003

Dietary fat modulation of apoA-II metabolism and prevention of senile amyloidosis in the senescence- accelerated mouse.

Senescence-accelerated mouse-prone (SAMP1; SAMP1@Umz) is an animal model of senile amyloidosis with apolipoprotein A-II (apoA-II) amyloid fibril (AApoAII) deposits. This study was undertaken to investigate the effects of dietary fats on AApoAII deposits in SAMP1 mice when purified diets containing 4% fat as butter, safflower oil, or fish oil were fed to male mice for 26 weeks. The serum HDL cholesterol was significantly lower (P < 0.01) in mice on the diet containing fish oil (7.4 +/- 3.0 mg/dl) than in mice on the butter diet (38.7 +/- 12.5 mg/dl), which in turn had significantly lower (P < 0.01) HDL levels than mice on the safflower oil diet (51.9 +/- 5.6 mg/dl). ApoA-II was also significantly lower (P < 0.01) in mice on the fish oil diet (7.6 +/- 2.7 mg/dl) than on the butter (26.9 +/- 7.3 mg/dl) or safflower oil (21.6 +/- 3.7 mg/dl) diets. The mice fed fish oil had a significantly greater ratio (P < 0.01) of apoA-I to apoA-II, and a smaller HDL particle size than those fed butter and safflower oil. Severe AApoAII deposits in the spleen, heart, skin, liver, and stomach were shown in the fish oil group compared with those in the butter and safflower oil groups (fish oil > butter > safflower oil group, P < 0.05). These findings suggest that dietary fats differ in their effects on serum lipoprotein metabolism, and that dietary lipids may modulate amyloid deposition in SAMP1 mice.

Aging, Premature↗
PubMed2003

Diurnal rhythm disorder of behavioral activity in SAMP1 mice is partially normalized by spontaneous wheel running.

We examined the diurnal rhythms of food and water intake, spontaneous wheel running (SWR), and spontaneous motor activity (SMA) in the SAMP1 strain, a mouse model of accelerated senescence. Without SWR exercise, food, and water intake in the SAMP1 mice was significantly higher during the light (L)-phase of the light-darkness (LD) cycle than in the control SAMR1 strain. Additionally, SWR and SMA activity rhythms were split in SAMP1 mice, as demonstrated by the appearance of a secondary peak starting from the end of the dark (D)-phase. SWR exercise significantly increased the percentages of nocturnal food and water intake and SMA in the SAMP1 mice, although food and water intake did not reach the level of control SAMR1 mice. Thus, the disordered diurnal rhythms in SAMP1 mice can be normalized, even if only partially, by SWR exercise.

Aging↗
PubMed2003

Amyloidosis modifier genes in the less amyloidogenic a/j mouse strain.

Apolipoprotein A-II is deposited as an amyloid fibril in aged mice (senile AApoAII amyloidosis). Although mouse strains with the apolipoprotein A-II c allele (Apoa2(c)) generally develop early-onset and severe senile amyloidosis, the A/J strain shows significantly less amyloid deposition. To identify genes that modify spontaneous amyloidosis development in the A/J mouse, we performed a genome-wide screening using hybrid mice derived from A/J and SAMP1 mice, which have Apoa2(c) and age-associated severe amyloid deposition. Our genetic analysis revealed that the lower levels of amyloidosis in the A/J strain were polygenically controlled. We found two chromosome locations associated with amyloidosis. One of these regions was in the chromosome 19 telomeric region, where the A/J alleles modify amyloidosis in an additive manner. The second region was in the chromosome 4 telomeric region, where the A/J alleles modify amyloidosis in a dominant manner. Perlecan and group II secretory phospholipase A2, located on the significantly linked region of chromosome 4, were compared in this study. These findings are for understanding the genetic mechanism of amyloidosis-related diseases and their prevention.

Amyloid↗