No abstract

One of the heat shock family protein (Hsp) expressing bacteria is the gram negative, periodontal pathogen Aggregatibacter actinomycetemcomitans (Aa). A. actinomycetemcomitans’ Hsp is a 64-kDa GroEL-protein, which has been shown to influence the host cells. In this study we used recombinant A. actinomycetemcomitans GroEL (rAaGroEL) protein as a model antigen to study GroEL-mediated T cell immune response. Human peripheral mononuclear cells (PBMCs), when stimulated with recombinant rAaGroEL, expressed early activation marker CD69 and IL-2R (CD25). CD25 and CD69 expressions were higher in CD4+ T cells compared to CD8+ T cells. rAaGroEL-responding CD4+ T cells expressed IL-10, IFNγ and TNFα cytokines. Interestingly, there were also IL-10 and IFNγ double cytokine producing CD4+ T cells. Additionally, IFNγ expressing CD4+ T cells were also T-bet positive. Altogether the results suggest that rAaGroEL protein affects CD4+ T cells to differentiate into IFNγ IL10-secreting T-bet+ Th1 cells.

No abstract

Recent studies point to the existence of poorly characterized small regulatory RNAs generated from mRNAs, rRNAs and tRNAs. To explore the subcellular location of tRNA-derived small RNAs, 0–1 and 7–8 h Drosophila embryos were fractionated on sucrose density gradients. Analysis of 12,553,921 deep-sequencing reads from unfractionated and fractionated Drosophila embryos has revealed that tRFs, which are detected mainly from the 5’ends of tRNAs, co-sediment with the non-polysomal fractions. Interestingly, the expression levels of a subset of tRFs change temporally following the maternal-to-zygotic transition in embryos. We detected non-polysomal association of tRFs in S2 cells as well. Differential tRF expression pattern points to developmental significance at the organismal level. These results suggest that tRFs are associated primarily with the non-polysomal complexes in Drosophila embryos and S2 cells.

Two nearly identical, gstD21(L) and gstD21(S) mRNAs, whose polyadenylation sites differ by 19 nucleotides, are transcribed from the intronless glutathione S-transferase D21 gene in Drosophila. Both mRNAs are intrinsically very labile, but exposure to pentobarbital renders them stabilized beyond what can be attributed to transcriptional activation. We have reconstituted this PBmediated mRNA stabilization in a transgene (D21L) that contains the full-length gstD21(L) sequence. We have also constructed a similar transgene (D21L-UTR), which matches D21L but excluded the native 3 -UTR. D21L-UTR produces a relatively stable RNA, whose stability is unaffected by pentobarbital. Following pentobarbital treatment of wild-type flies, the levels of gstD21(L) and gstD21(S) mRNAs hold at a relatively constant ratio (L/S) of 1.4 ؎ 0.2. In transgenic flies, heat shock induction of D21L mRNA changed the L/S ratio to 0.6 ؎ 0.1, and it was further reduced to 0.3 ؎ 0.1 as D21L mRNA accumulated in the presence of PB. The ratio returned nearly normal (1.1 ؎ 0.1) as the D21L mRNA decayed over 12 h after terminating induction. In constrast, when D21L-UTR was present, the ratio remained constant (1.7 ؎ 0.2) even under various induction conditions and during recovery. Thus, the 3 -UTR, which was the critical difference between these two transgenes, must have some role in determining the L/S ratio. Induced D21L mRNA alone is not sufficient to cause reversible changes in the ratio. Such changes require the presence of pentobarbital. Therefore, pentobarbital may regulate this L/S ratio by affecting the choice of polyadenylation sites for the gstD21 mRNAs through sensing the concentrations of the native 3 -UTR sequences.