AA amyloidosis-resistant CE/J mice have Saa1 and Saa2 genes that encode an identical SAA isoform

The CE/J mouse strain is resistant to amyloid A protein (AA) amyloidosis. In contrast to AA amyloidosis-susceptible mouse strains that concomitantly express serum amyloid A precursor protein (SAA) types 1 and 2 isoforms encoded by the Saa1 and Saa2 genes, respectively, in response to inflammatory stimulation from the liver, CE/J mice express only a single SAA isoform named SAA2.2. In addition, CE/J mice uniquely possess a Q30L amino acid substitution in SAA2.2 that inhibits amyloidogenesis. To elucidate the genetic basis underlying the expression of only a single SAA isoform in this strain, we conducted PCR cloning and nucleotide sequencing of the Saa1 and Saa2 genes from the CE/J genome. We revealed that CE/J mice possess functional Saa1 and Saa2 genes. Intriguingly, the two genes were identical with respect to amino acid sequence, each encoding the SAA2.2 isoform. RT-PCR analysis of inflamed liver tissue from CE/J mice demonstrated that both genes are expressed at equivalent levels. Reporter assays revealed that promoter/enhancer sequences of Saa1 and Saa2 genes in CE/J are also functional. These results indicate that the SAA2.2 isoform in CE/J is a mixture of Saa1 and Saa2 gene products.ArticleAMYLOID-JOURNAL OF PROTEIN FOLDING DISORDERS. 21(1):1-8 (2014)journal articl

Hereditary cataract of the Nakano mouse: Involvement of a hypomorphic mutation in the coproporphyrinogen oxidase gene

The Nakano cataract (NCT) is a recessive disorder in the mouse linked to the nct locus on chromosome 16. In this study, we positionally cloned the critical gene in the nct locus. Herein, we report that cataracts in the BALB/c-nct/nct mouse are caused by a hypomorphic mutation in the coproporphyrin oxidase gene (Cpox), encoding the enzyme responsible for catalyzing oxidative decarboxylation of the heme precursor, coproporphyrinogen III, in the heme biosynthetic pathway. BALB/c-nct/nct mice are homozygous for a G to T nucleotide substitution in the Cpox gene, which results in a p.R380L amino acid substitution in the CPDX protein. The CPDX isoform with the p.R380L substitution retained only 15% of the activity of the wild type isoform. BALB/c-nct/nct mice had excessive accumulation of coproporphyrin HI in the lens. The NCT phenotype was normalized by the introduction of a wild type Cpox transgene. The mechanisms by which impairment of CPDX leads to lens opacity in the NCT are elusive. However, our data illuminate a hitherto unanticipated involvement of the heme biosynthesis pathway in lens physiology.ArticleEXPERIMENTAL EYE RESEARCH. 112:45-50 (2013)journal articl

Development of congenic strains of mice carrying amyloidogenic apolipoprotein A-II (Apoa2c) Apoa2c reduces the plasma level and the size of high density lipoprotein

AbstractA congenic strain of mice with amyloidogenic apolipoprotein A-II (Apoa2c) on the genetic background of the amyloidosis-resistant SAM-R/1 strain was produced by 12 generations of backcrossing. Genome mapping using endogenous murine leukemia proviral markers was done in the congenic strain, termed R1·P1-Apoa2c. We confirmed that only a small region surrounding the apoA-II gene on chromosome 1 was transferred from the genome of the donor SAM-P/1 strain. The level and particle size of plasma high density lipoprotein were decreased in RI · Pl-Apoa2c mice compared to those in the progenitor SAM-R/1 mice. The function of apoA-II can be studied using this strain of mice

Distribution of Transmissible Amyloid Proteins in the Liver with Apolipoprotein A-II Amyloidosis

Article信州医学雑誌 64(4): 183-194(2016)journal articl

Amyloid fibrils formed by selective N-, C-terminal sequences of mouse apolipoprotein A-II

In mice, amyloidogenic type C apolipoprotein A-II (apoA-II) forms amyloid fibrils in age-associated amyloidosis. To understand the mechanism of amyloid fibril formation by apoA-II, we examined the polymerization of synthetic partial peptides of apoA-II in vitro. None of the partial apoA-II peptides polymerized into amyloid fibrils when tested as a single species mixture. We found a unique mechanism in which N- and C-terminal peptides associated into amyloid fibrils in a 1:1 ratio at pH 2.5. The 11-residue amino acid sequence (6-16), which is a common sequence of type B apoA-II and type C apoA-II proteins in amyloidosis-resistant mice and amyloidosis-susceptible mice, respectively, was critical for polymerization into amyloid fibrils. The 18-residue-long amino acid sequence (48-65) is also necessary for nucleation, but not for the extension phase. These findings suggest that there may be different mechanisms underlying the nucleation and extension phases of apoA-II amyloid fibril formation. We also found that amino acid substitutions between type B apoA-II (Pro5, Val38) and type C apoA-II (Gln5, Ala38) did not affect either phase. The strategy of using synthetic partial peptides of amyloidogenic proteins in vitro is a useful system for understanding amyloid fibril formation and for the development of novel therapies.ArticleBIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS. 1794(10):1517-1529 (2009)journal articl

Insights into the structural basis of amyloid resistance provided by cryo-EM structures of AApoAII amyloid fibrils

Amyloid resistance is the inability or the reduced susceptibility of an organism to develop amyloidosis. In this study we have analysed the molecular basis of the resistance to systemic AApoAII amyloidosis, which arises from the formation of amyloid fibrils from apolipoprotein A-II (ApoA-II). The disease affects humans and animals, including SAMR1C mice that express the C allele of ApoA-II protein, whereas other mouse strains are resistant to development of amyloidosis due to the expression of other ApoA-II alleles, such as ApoA-IIF. Using cryo-electron microscopy, molecular dynamics simulations and other methods, we have determined the structures of pathogenic AApoAII amyloid fibrils from SAMR1C mice and analysed the structural effects of ApoA-IIF-specific mutational changes. Our data show that these changes render ApoA-IIF incompatible with the specific fibril morphologies, with which ApoA-II protein can become pathogenic in vivo

Effects of mild calorie restriction and high-intensity interval walking in middle-aged and older overweight Japanese

We investigated whether a combination of mild calorie restriction (MCR) and high-intensity interval walking (HIW) improved physical fitness more than HIW alone in middle-aged and older overweight Japanese (40-69 years old, BMI >= 23.6 kg/m(2)). Forty-seven women and 16 men were divided into MCR + HIW and HIW groups. All subjects performed HIW: >= 5 sets of 3-min low-intensity walking (40% peak aerobic capacity for walking, VO2peak) and 3-min high-intensity walking (>= 70% VO2peak) per day, >= 4 days per week, for 16 weeks while energy expenditure was monitored with a tri-axial accelerometer. The MCR + HIW group consumed meal replacement formula (240 kcal): a mixture of low-carbohydrates and -fat and high-protein, for either lunch or dinner everyday and therefore, had similar to 87% of the energy intake of the HIW group during the intervention period. Although the HIW group showed improvements in BMI, blood pressure, and several blood chemicals, the MCR + HIW group had greater improvement. Moreover, the medical expenditure for the 6 months including the intervention period was 59% lower in the MCR + HIW group than in the HIW group. Our strategy of a short-term combination of MCR and HIW may thus prevent lifestyle-associated diseases and improve health in middle-aged and older overweight Japanese.ArticleEXPERIMENTAL GERONTOLOGY. 44(10):666-675 (2009)journal articl