BAFFR activates PI3K/AKT signaling in human naive but not in switched memory B cells through direct interactions with B cell antigen receptors.

Binding of BAFF to BAFFR activates in mature B cells PI3K/AKT signaling regulating protein synthesis, metabolic fitness, and survival. In humans, naive and memory B cells express the same levels of BAFFR, but only memory B cells seem to survive without BAFF. Here, we show that BAFF activates PI3K/AKT only in naive B cells and changes the expression of genes regulating migration, proliferation, growth, and survival. BAFF-induced PI3K/AKT activation requires direct interactions between BAFFR and the B cell antigen receptor (BCR) components CD79A and CD79B and is enhanced by the AKT coactivator TCL1A. Compared to memory B cells, naive B cells express more surface BCRs, which interact better with BAFFR than IgG or IgA, thus allowing stronger responses to BAFF. As ablation of BAFFR in naive and memory B cells causes cell death independent of BAFF-induced signaling, BAFFR seems to act also as an intrinsic factor for B cell survival

Comparative Genome Analysis of 33 Chlamydia Strains Reveals Characteristic Features of Chlamydia Psittaci and Closely Related Species

To identify genome-based features characteristic of the avian and human pathogen Chlamydia (C.) psittaci and related chlamydiae, we analyzed whole-genome sequences of 33 strains belonging to 12 species. Using a novel genome analysis tool termed Roary ILP Bacterial Annotation Pipeline (RIBAP), this panel of strains was shown to share a large core genome comprising 784 genes and representing approximately 80 of individual genomes. Analyzing the most variable genomic sites, we identified a set of features of C. psittaci that in its entirety is characteristic of this species: (i) a relatively short plasticity zone of less than 30,000 nt without a tryptophan operon (also in C. abortus, C. avium, C. gallinacea, C. pneumoniae), (ii) a characteristic set of of Inc proteins comprising IncA, B, C, V, X, Y (with homologs in C. abortus, C. caviae and C. felis as closest relatives), (iii) a 502-aa SinC protein, the largest among Chlamydia spp., and (iv) an elevated number of Pmp proteins of subtype G (14 in C. psittaci, 14 in Cand. C. ibidis). In combination with future functional studies, the common and distinctive criteria revealed in this study provide important clues for understanding the complexity of host-specific behavior of individual Chlamydia spp.1. Introduction 2. Results 2.1. General Characteristics of the Genome Sequences Basic genomic parameters of all 33 strains are given 2.2. Common and Unique Elements in the Genomes of Chlamydia spp. 2.3. The Plasticity Zone (PZ) 2.4. Genes Encoding Polymorphic Membrane Proteins (pmps) 2.5. Inc Proteins 2.6. The Secreted Inner Nuclear Membrane-Associated Chlamydia Protein (SINC) 2.7. Histone-Like Proteins HctA and HctB 2.8. Pseudogenes 3. Discussion 3.1. Bioinformatics Tools: New and Unique Features of the RIBAP 3.2. Core Genome vs. Dispensable Genome 3.3. The Plasticity Zone 3.4. The Family of Polymorphic Membrane Proteins (Pmps) 3.5. Inclusion Membrane Proteins 3.6. SINC Protein 3.7. Histone-Like Proteins HctA and HctB 3.8. Pseudogenes 4. Materials and Methods 4.1. Chlamydial Strains 4.2. Genome Sequencing and Genome Assembly 4.3. Pan-Genome and Core Genome Calculation Using RIBAP 4.4. Annotation 4.5. Pan- Genome Scaffold 4.6. Integer Linear Programming and GLPK 4.7. Creating a RIBAP Group 4.8. The RIBAP Output 4.9. Phylogenetic Tree Based on Core Genomes 4.10. UpSet Diagrams 4.11. Multiple Blast to Identify Homologs of Pmp, Inc and SinC Genes 4.12. Calculation of Sequence Identities 4.13. Normalization of Genomes 5. Conclusion