bims-polyam 2019-07-21 papers

Biochem Biophys Res Commun. 2019 Jul 10. pii: S0006-291X(19)31358-0. [Epub ahead of print]

Polyamine oxidase 2 is involved in regulating excess spermidine contents during seed germination and early seedling development in Arabidopsis thaliana.

Yoshihiro Takahashi, Tatsuaki Uemura, Yuuta Teshima.

To understand the physiological functions of polyamine oxidases (PAOs) in plants, we analyzed the effects of exogenous polyamines during seed germination and early seedling development, using Arabidopsis thaliana lines independently harboring T-DNA insertions in each PAO gene. Spermine caused seedling growth inhibition but did not affect the germination in all lines including wild-type Col-0. However, an AtPAO2 knockout mutant, -pao2, could not germinate under excess spermidine (Spd) conditions. The root growth rates of post-germination -pao2 seedlings were also strongly inhibited by the Spd treatment compared with the wild-type plants. AtPAO2 has a conserved peroxisome-targeting signal sequence at its C-terminus. We prepared two types of AtPAO2 expression plants in a -pao2 background. In -pao2/PAO2 plants a 5.8-kbp genomic fragment containing the complete coding sequence of AtPAO2 was introduced, while in -pao2/PAO2ΔC plants the same fragment lacking the peroxisome-targeting signal was introduced. The Spd-sensitive phenotypes observed in -pao2 were completely recovered in both of the transgenic complementation lines. Thus, AtPAO2 appears to be involved in excess Spd catabolism during seed germination and early seedling development irrespective of subcellular localization.

Keywords: Arabidopsis thaliana; Germination; Polyamine oxidase 2; Root growth; Spermidine

DOI: https://doi.org/10.1016/j.bbrc.2019.07.022

Sci Rep. 2019 Jul 18. 9(1): 10425

Metabolomic Analysis of Skeletal Muscle in Aged Mice.

Ran Uchitomi, Yukino Hatazawa, Nanami Senoo, Kiyoshi Yoshioka, Mariko Fujita, Takahiko Shimizu, Shinji Miura, Yusuke Ono, Yasutomi Kamei.

Sarcopenia is the age-induced, progressive loss of skeletal muscle mass and function. To better understand changes in skeletal muscle during sarcopenia, we performed a metabolomic analysis of skeletal muscle in young (8-week-old) and aged (28-month-old) mice by using capillary electrophoresis with electrospray ionization time-of-flight mass spectrometry. Principal component analysis showed clear changes in metabolites between young and aged mice. Glucose metabolism products were decreased in aged mice, specifically fructose 1,6-diphosphate (0.4-fold) and dihydroxyacetone phosphate (0.6-fold), possibly from decreased glycolytic muscle fibers. Multiple metabolic products associated with phospholipid metabolism were significantly changed in aged mice, which may reflect changes in cell membrane phospholipids of skeletal muscle. Products of polyamine metabolism, which are known to increase nucleic acid and protein synthesis, decreased in spermine (0.5-fold) and spermidine (0.6-fold) levels. By contrast, neurotransmitter levels were increased in skeletal muscle of aged mice, including acetylcholine (1.8-fold), histamine (2.6-fold), and serotonin (1.7-fold). The increase in acetylcholine might compensate for age-associated dropout of neuromuscular junctions, whereas the increases in histamine and serotonin might be due to muscle injury associated with aging. Further analysis focusing on the altered metabolites observed in this study will provide essential data for understanding aging muscles.

DOI: https://doi.org/10.1038/s41598-019-46929-8

Curr Opin Microbiol. 2019 Jul 12. pii: S1369-5274(18)30114-0. [Epub ahead of print]52 110-115

The impact of arginase activity on virulence factors of Leishmania amazonensis.

Juliana Ide Aoki, Maria Fernanda Laranjeira-Silva, Sandra Marcia Muxel, Lucile Maria Floeter-Winter.

The outcome of Leishmania infection depends on the parasite species and the host immune response. Virulence factors have been extensively studied over the years in an effort to find efficient vaccines and/or treatments for Leishmania infection. Arginase activity in Leishmania has been described as an essential player for the polyamines pathway, impacting parasite replication and infectivity. Considering previous studies showing that the absence of arginase activity leads to low infectivity of Leishmania amazonensis, we reanalyzed transcriptomic data comparing both promastigotes and axenic amastigotes from L. amazonensis wild type (La-WT) and L. amazonensis arginase knockout (La-arg-) backgrounds. The analysis produced a new compilation of modulated transcripts that indicated the role of arginase not only in the polyamines pathway but also in the modulation of virulence factors involved in parasite recognition, growth and differentiation.

DOI: https://doi.org/10.1016/j.mib.2019.06.003