T cells of atomic bomb survivors respond poorly to stimulation by Staphylococcus aureus toxins in vitro: does this stem from their peripheral lymphocyte populations having a diminished naïve CD4 T-cell content?

We found previously that the peripheral CD4 T-cell populations of heavily exposed A-bomb survivors contained fewer na?ve T cells than we detected in the corresponding unexposed controls. To determine whether this demonstrable impairment of the CD4 T-cell immunity of A-bomb survivors was likely to affect the responsiveness of their immune systems to infection by common pathogens, we tested the T cells of 723 survivors for their ability to proliferate in vitro after a challenge by each of the Staphylococcus aureus toxins SEB, SEC-2, SEC-3, SEE and TSST-1. The results presented here reveal that the proliferative responses of T cells of A-bomb survivors became progressively weaker as the radiation dose increased and did so in a manner that correlated well with the decreasing CD45RA-positive (na?ve) [but not CD45RA-negative (memory)] CD4 T-cell percentages that we found in their peripheral blood lymphocyte (PBL) populations. We also noted that the T cells of survivors with a history of myocardial infarction tended to respond poorly to several (or even all) of the S. aureus toxins, and that these same individuals had proportionally fewer CD45RA-positive (na?ve) CD4 T cells in their PBL populations than we detected in survivors with no myocardial infarction in their history. Taken together, these results clearly indicate that A-bomb irradiation led to an impairment of the ability of exposed individuals to maintain their na?ve T-cell pools. This may explain why A-bomb survivors tend to respond poorly to toxins encoded by the common pathogenic bacterium S. aureus.     

X-Linked inhibitor of apoptosis protein is involved in mutant SOD1-mediated neuronal degeneration

Mutations in the superoxide dismutase 1 (SOD1) gene cause the degeneration of motor neurons in familial amyotrophic lateral sclerosis (FALS). An apoptotic process including caspase-1 and -3 has been shown to participate in the pathogenesis of FALS transgenic (Tg) mouse model. Here we report that IAP proteins, potent inhibitors of apoptosis, are involved in the FALS Tg mouse pathologic process. The levels of X-linked inhibitor of apoptosis protein (XIAP) mRNA and protein were significantly decreased in the spinal cord of symptomatic G93A-SOD1 Tg mice compared with littermates. In contrast, the levels of cIAP-1 mRNA and protein were increased in symptomatic G93A-SOD1 Tg mice, whereas the levels of cIAP-2 mRNA and protein were unchanged. In situ hybridization showed that the expression of XIAP was remarkably reduced in the motor neurons of Tg mice, and the expression of cIAP-1 was strongly increased in the reactive astrocytes of Tg mice. Overexpression of XIAP markedly inhibited the cell death and caspase-3 activity in the neuro2a cells expressing mutant SOD1. Deletional mutant analysis revealed that the N-terminal domain of XIAP, the BIR1-2 domains, was essential for this inhibitory activity. These results suggest that XIAP plays a role in the apoptotic mechanism in the progression of disease in mutant SOD1 Tg mice and holds therapeutic possibilities for FALS.     

Priming effects of novel nonsteroidal progesterone receptor modulators CP8816 and CP8863 on the development of adenomyosis in the mouse uterus

The possibility of therapeutic application of novel nonsteroidal progesterone receptor modulators CP8816 and CP8863 for preventing the development of uterine adenomyosis was investigated in mice. First priming effects of CP8816 on 17beta-estradiol (E2)-induced cell division in uterine tissues were examined. As a result, pretreatment with CP8816 or progesterone significantly suppressed the elevation of the mitotic activity in the luminal epithelial cells of mice treated with E2 later. Priming with CP8816 had little effect on the stromal cells, but progesterone priming caused an increase of stromal mitotic activity in mice treated with E2 later. To evaluate the inhibitory effect of these compounds on the development of adenomyosis induced experimentally by pituitary grafting, 7-week-old female mice were isografted with a single anterior pituitary in the uterus and divided into four groups. Two groups of mice were given daily subcutaneous injections of 1 mg of CP8816 or the vehicle alone for 6 weeks from the day after the grafting. Remaining two groups of mice were given oral administration of 1 mg of CP8863 or the vehicle only for 5 weeks starting one week after the grafting. The incidence of adenomyosis was significantly lower in the groups of mice treated with CP8816 and CP8863 than in the respective control groups. The mechanism by which CP compounds inhibited the development of adenomyosis might be related to their priming effects, i.e., their inhibitory effect on epithelial cell division and lack of effect on stromal cell division after subsequent exposure to E2.     

Intracellular redox regulation by a cystine derivative suppresses UV-induced NF-kappa B activation

Nuclear factor (NF)-kappa B pathways are influenced by the intracellular reduction-oxidation (redox) balance. While NF-kappa B is activated through inhibitor (I)-kappa B degradation by oxidative stress, its DNA binding is accelerated in the reduced state. We found that N,N'-diacetyl-L-cystine dimethylester (DACDM) suppressed the UVB-induced NF-kappa B binding activity at a much lower concentration (50-100 microM) than N-acetyl-L-cysteine (NAC, 10-30 mM). While NAC suppressed the I-kappa B degradation but not the DNA binding, DACDM prevented the activated NF-kappa B from binding DNA, without influencing the I-kappa B degradation. These properties of DACDM make it possible to effectively regulate the intracellular redox balance.     

Recovery of photosynthetic systems during rewetting is quite rapid in a terrestrial cyanobacterium, Nostoc commune

Recovery processes of photosynthetic systems during rewetting were studied in detail in a terrestrial, highly drought-tolerant cyanobacterium, Nostoc commune. With absorption of water, the weight of N. commune colony increased in three phases with half-increase times of about 1 min, 2 h and 9 h. Fluorescence intensities of phycobiliproteins and photosystem (PS) I complexes were recovered almost completely within 1 min, suggesting that their functional forms were restored very quickly. Energy transfer from allophycocyanin to the core-membrane linker peptide (L(CM)) was recovered within 1 min, but not that from L(CM) to PSII. PSI activity and cyclic electron flow around PSI recovered within 2 min, while the PSII activity recovered in two phases after a time lag of about 5 min, with half times of about 20 min and 2 h. Photosynthetic CO(2) fixation was restored almost in parallel with the first recovery phase of the PSII reaction center activity. Although the amount of absorbed water became more than 20 times the initial dry weight of the N. commune colony in the presence of sufficient water, about twice the initial dry weight was enough for recovery and maintenance of the PSII activity.     

Chloroplast division machinery as revealed by immunofluorescence and electron microscopy

The division of chloroplasts (plastids) is critical for the viability of photosynthetic eukaryotes. Previously we reported on the chloroplast division apparatus, which consists of inner and outer double or triple rings (PD rings). Chloroplasts are assumed to arise from bacterial endosymbionts, while bacterial division is instigated by a bacterial cytokinesis Z-ring protein (FtsZ). Here we present immunofluorescence and electron-microscopic evidence of chloroplast division via complex machinery involving the FtsZ and PD rings in the higher plant Pelargonium zonale Ait. Prior to invagination, the FtsZ protein was attached to a ring at the stromal division site. Following formation of the FtsZ ring, the inner stromal and outer cytosolic PD rings appeared, signifying the initiation of invagination. The FtsZ ring and the PD rings were found at the leading edge of chloroplast constriction throughout division. During chloroplast division, neither the FtsZ nor the inner rings changed width, but the volume of the outer ring gradually increased. We suggest that the FtsZ ring determines the division region, after which the inner and outer PD rings are formed as a lining for the FtsZ ring. With the outer ring providing the motivating force, the FtsZ and inner PD rings ultimately decompose to their base components.     

Biotransformation of L-lysine to L-pipecolic acid catalyzed by L-lysine 6-aminotransferase and pyrroline-5-carboxylate reductase

The enzyme involved in the reduction of delta1-piperideine-6-carboxylate (P6C) to L-pipecolic acid (L-PA) has never been identified. We found that Escherichia coli JM109 transformed with the lat gene encoding L-lysine 6-aminotransferase (LAT) converted L-lysine (L-Lys) to L-PA. This suggested that there is a gene encoding "P6C reductase" that catalyzes the reduction of P6C to L-PA in the genome of E. coli. The complementation experiment of proC32 in E. coli RK4904 for L-PA production clearly shows that the expression of both lat and proC is essential for the biotransformation of L-Lys to L-PA. Further, We showed that both LAT and pyrroline-5-carboxylate (P5C) reductase, the product of proC, were needed to convert L-Lys to L-PA in vitro. These results demonstrate that P5C reductase catalyzes the reduction of P6C to L-PA. Biotransformation of L-Lys to L-PA using lat-expressing E. coli BL21 was done and L-PA was accumulated in the medium to reach at an amount of 3.9 g/l after 159 h of cultivation. It is noteworthy that the ee-value of the produced pipecolic acid was 100%.     

Solution structure of paralytic peptide of silkworm,Bombyx mori

Paralytic peptide of Bombyx mori (BmPP) is one of the multifunctional ENF-peptides; the name of “ENF” is the consensus N-terminal amino acid sequence of the family peptides. We revealed that BmPP significantly possesses growth-blocking activity and plasmatocyte-spreading activity and that its activity profiles are different from those of another ENF-family peptide, namely, the growth-blocking peptide of Pseudaletia separata (PsGBP). We also determined the NMR structures of BmPP and PsGBP under the same conditions, which revealed the structural differences of the first and second β-turn regions between the two peptides. On the basis of our results, it can be considered that the tertiary structural difference in these peptides may cause their different profiles of growth-blocking activity.