Abstracts of papers (2011)

Last Update: 11/28/2011

Abstracts of papers (2011)

[2011-1] Yoshida, M. et al., Clin. Chim. Acta 412, 339-342 (2011)

Background: We have recently found that the median relative risk value (RRV) (0-1) of brain infarction estimated by protein-conjugated acrolein (PC-Acro), IL-6 and CRP together with age was in the order silent brain infarction (SBI) (0.80)>carotid atherosclerosis (CA) (0.76)>white matter hyperintensity (WMH) (0.46)>control (0.14). We clarified how metabolic disorders [hypertension (HT), hyperlipidemia (HL) and hyperglycemia (HG)] are correlated with RRV.
Methods: The levels of PC-Acro, IL-6 and CRP in plasma were measured by ELISA. SBI and WMH were evaluated by MRI, and CA was evaluated by duplex carotid ultrasonography.
Results: The median RRV of metabolic disorders was in the order HT+HG (0.84)>HT+HL (0.73)>HT (0.65)~HG (0.65)>HL (0.61)>HL+HG (0.48)>no metabolic disorder (0.24)>normal (0.11). Correlation with SBI was in the order HT+HG (52%)>HT+HL (42%)>HT (40%)>HG (34%)~HL(33%)>HL+HG (14%)~no metabolic disorder (14%).
Conclusion: The results indicate that HT is the most strongly associated factor with SBI among metabolic disorders and that the seriousness of metabolic disorder estimated by RRV was well correlated with SBI.

[2011-2] Saiki, R. et al., Bioichem. Biophys. Res. Commun. 404, 1044-1049 (2011)

Although it is thought that the major factor responsible for cell damage is reactive oxygen species (ROS), our recent studies have shown that acrolein is more toxic than ROS. Thus, the relative importance of acrolein and ROS in cell damage during brain infarction was compared using photochemically induced thrombosis model mice. The levels of acrolein-conjugated albumin, and of 4-hydroxynonenal (HNE)-conjugated albumin and 8-OHdG were evaluated as indicators of damage produced by acrolein and ROS, respectively. The increase in acrolein-conjugated albumin was much greater than the increase in HNE-conjugated albumin or 8-OHdG, suggesting that acrolein is more strongly involved in cell damage than ROS during brain infarction. It was also shown that infarction led more readily to RNA damage than to DNA or phospholipid damage. As a consequence, polyamines were released from RNA, and acrolein was produced from polyamines, especially from spermine by spermine oxidase. Production of acrolein from spermine by spermine oxidase was clarified using spermine synthase-deficient Gy mice and transglutaminase 2-knockout mice, in which spermine content is negligible or spermidine/spermine N1-acetyltransferase activity is elevated.

[2011-3] Igarashi, K., and Kashiwagi, K., Methods Mol. Biol. 720, 51-65 (2011)

Polyamines are essential for normal cell growth and exist mainly as RNA-polyamine complexes in cells. Thus, effects of polyamines on protein synthesis have been studied. It was found that several kinds of protein synthesis, which are important for cell growth, were enhanced by polyamines at the level of translation. We proposed that a group of genes whose expression is enhanced by polyamines at the level of translation be referred to as a "polyamine modulon." In Escherichia coli, most members of the polyamine modulon thus far identified were transcription factors. These transcription factors enhanced the synthesis of several kinds of mRNA and tRNA, and also rRNA. In this way, polyamines enhanced growth of E. coli. We also succeeded in identifying three kinds of "polyamine modulon" in mammalian cells. One of the mechanisms of polyamine stimulation at the molecular level was due to the stabilization of the bulged-out region of double-stranded RNA in mRNA. The procedures used to identify components of the polyamine modulon are described in this chapter.

[2011-4] Kashiwagi, K., and Igarashi, K., Methods Mol. Biol. 720, 295-308 (2011)

Polyamine content in cells is regulated by biosynthesis, degradation, and transport. With regard to transport, uptake and excretion proteins exist in Escherichia coli and Saccharomyces cerevisiae. In E. coli, the uptake systems comprise a spermidine-preferential uptake system consisting of the PotA, B, C, and D proteins, and a putrescine-specific uptake system consisting of the PotF, G, H, and I proteins. Two other proteins, PotE and CadB, each containing 12 transmembrane segments, function as antiporters (putrescine-ornithine and cadaverine-lysine) and are important for cell growth at acidic pH. MdtJI was identified as a spermidine excretion system. When putrescine was used as energy source, PuuP functioned as a putrescine transporter. In S. cerevisiae, DUR3 and SAM3, containing 16 or 12 transmembrane segments, are the major polyamine uptake proteins, whereas TPO1 and TPO5, containing 12 transmembrane segments, are the major polyamine excretion proteins, and UGA4 is a putrescine transporter on the vacuolar membrane. The activities of DUR3 and TPO1 are regulated by phosphorylation of serine/threonine residues. The identification and assay procedures of these transporters are described in this chapter.

[2011-5] Igarashi, K., and Kashiwagi, K., Methods Mol. Biol. 720, 395-408 (2011)

Acrolein and H2O2 are among the metabolic products of spermine and spermidine, and it was found that acrolein was more toxic than H2O2. It was determined whether acrolein can serve as a biochemical marker for stroke (brain infarction) and chronic renal failure. Since acrolein rapidly reacts with lysine residues in protein, protein-conjugated acrolein (PC-Acro) was measured. PC-Acro was increased at the locus of brain infarction and in plasma in a mouse model of stroke involving photochemically induced thrombosis. An increase in PC-Acro in plasma was found to be a good biochemical marker in patients with stroke or with chronic renal failure. Using a receiver operating characteristic curve, the combined measurement of PC-Acro, IL-6 and CRP together with age indicated silent brain infarction (SBI) with 89% sensitivity and 91% specificity. The procedures to measure PC-Acro and polyamine oxidases [spermine oxidase (SMO) and acetylpolyamine oxidase (ACPAD)], and its application as markers in stroke and chronic renal failure are described in this chapter.

[2011-6] Hamdan, F. F. et al., Am. J. Hum. Genet. 88, 306-316 (2011)

Little is known about the genetics of nonsyndromic intellectual disability (NSID). We hypothesized that de novo mutations (DNMs) in synaptic genes explain an important fraction of sporadic NSID cases. In order to investigate this possibility, we sequenced 197 genes encoding glutamate receptors and a large subset of their known interacting proteins in 95 sporadic cases of NSID. We found 11 DNMs, including ten potentially deleterious mutations (three nonsense, two splicing, one frameshift, four missense) and one neutral mutation (silent) in eight different genes. Calculation of point-substitution DNM rates per functional and neutral site showed significant excess of functional DNMs compared to neutral ones. De novo truncating and/or splicing mutations in SYNGAP1, STXBP1, and SHANK3 were found in six patients and are likely to be pathogenic. De novo missense mutations were found in KIF1A, GRIN1, CACNG2, and EPB41L1. Functional studies showed that all these missense mutations affect protein function in cell culture systems, suggesting that they may be pathogenic. Sequencing these four genes in 50 additional sporadic cases of NSID identified a second DNM in GRIN1 (c.1679_1681dup/p.Ser560dup). This mutation also affects protein function, consistent with structural predictions. None of these mutations or any other DNMs were identified in these genes in 285 healthy controls. This study highlights the importance of the glutamate receptor complexes in NSID and further supports the role of DNMs in this disorder.

[2011-7] Kawano-Kawada, M. et al., J. Bacteriol. 193, 3657-3661 (2011)

A Glu139Asp mutant of the NtpK subunit (kE139D) of Enterococcus hirae vacuolar-type ATPase (V-ATPase) lost tolerance to sodium but not to lithium at pH 10. Purified kE139D V-ATPase retained relatively high specific activity and affinity for the lithium ion compared to the sodium ion. The kE139 residue of V-ATPase is indispensable for its enzymatic activity that is linked with the salt tolerance of enterococci.

[2011-8] Igarashi, K., and Kashiwagi, K., Mol. Nutr. Food Res. 55, 1332-1341 (2011)

The relationship between acrolein (CH2=CH-CHO) and brain infarction is the focus of this review. It has been found that acrolein is produced mainly within cells from polyamines by polyamine oxidases (PAOs), especially from spermine by spermine oxidase during cell damage, and that acrolein is more toxic than reactive oxygen species (ROS) in a cell culture system. Thus, the possibility that acrolein and PAOs are good biochemical markers of stroke was tested because there are no other reliable biochemical markers at the early stage of stroke. Levels of protein-conjugated acrolein (PC-Acro) and PAOs (acrolein-producing enzymes) were significantly increased in the plasma of stroke patients. The multiplied value of PC-Acro by PAOs was nearly parallel with the size of stroke. Furthermore, when the combined measurements of PC-Acro, interleukin-6 (IL-6) and C-reactive protein (CRP) were evaluated along with age using a receiver operating characteristic (ROC) curve, even silent brain infarction (SBI), which is a small brain infarction, was indicated with approximately 84% sensitivity and specificity. These findings clearly indicate that acrolein is strongly correlated with cell damage during brain infarction.