No abstract

The gene for murine Ia-associated invariant (1i) chains (1131 and 1i41) was characterized by sequence analysis. The gene extends over -9 kb and is organized in nine exons. Exon 1 encodes the 5' untranslated region and the cytoplasmic segment, exon 2 the membrane spaniing segment and adjacent amino acids and exons 3-8 the extracytoplasmic portion of 1131. Putative promoter sequences were found upstream of the start of the coding sequence. Between exons 6 and 7 an additional, alternatively spliced exon 6b has been identified. This exon is spliced into the mRNA coding for the li-related Ii41 protein. Exon 6b encodes a cysteine-rich domain of 64 amino acids. It shows a remarkably high homology to the repetitive elements in thyroglobulin, a precursor for thyroid hormone. Based on this homology, it is suggested that this domain (TgR) in Tg and in 1141 may play a role either in hormone formation or as a carrier in the transport of molecules (thyroid hormone or processed antigen respectively) between intracellular compartments.

The interplay between keratinocytes and immune cells, especially T cells, plays an important role in the pathogenesis of chronic inflammatory skin diseases. During psoriasis, keratinocytes attract T cells by releasing chemokines, while skin-infiltrating selfreactive T cells secrete proinflammatory cytokines, e.g., IFNγ and IL-17A, that cause epidermal hyperplasia. Similarly, in chronic graftversus-host disease, allogenic IFNγ-producing Th1/Tc1 and IL-17-producing Th17/Tc17 cells are recruited by keratinocyte-derived chemokines and accumulate in the skin. However, whether keratinocytes act as nonprofessional antigen-presenting cells to directly activate naive human T cells in the epidermis remains unknown. Here, we demonstrate that under proinflammatory conditions, primary human keratinocytes indeed activate naive human T cells. This activation required cell contact and costimulatory signaling via CD58/CD2 and CD54/LFA-1. Naive T cells costimulated by keratinocytes selectively differentiated into Th1 and Th17 cells. In particular, keratinocyte-initiated Th1 differentiation was dependent on costimulation through CD58/CD2. The latter molecule initiated STAT1 signaling and IFNγ production in T cells. Costimulation of T cells by keratinocytes resulting in Th1 and Th17 differentiation represents a new explanation for the local enrichment of Th1 and Th17 cells in the skin of patients with a chronic inflammatory skin disease. Consequently, local interference with T cell-keratinocyte interactions may represent a novel strategy for the treatment of Th1 and Th17 cell-driven skin diseases.In addition, in chronic graft-versus-host disease (GVHD), a major complication of allogenic stem cell transplantation, the KCmediated secretion of chemokines (CXCL9 and CXCL10) leads to the recruitment of alloreactive T cells into the skin. 14 These allogenic T cells predominantly belong to the IFNγ-producing Th1/ Tc1 and IL-17-producing Th17/Tc17 subpopulations and cause cutaneous manifestations, e.g., follicular erythema. [15][16][17] Although the pivotal role of KCs in non-contact-mediated communication during chronic skin inflammation is quite well understood, the direct interaction between KCs and T cells remains elusive. In particular, the potential of KCs to act as nonprofessional APCs, enabling them to costimulate T cells directly in the skin, is still debated.T cells require two distinct signals for activation and clonal expansion. The first signal is transmitted by the antigen-specific T cell receptor (TCR) on T cells, following recognition of antigenic peptides loaded on MHC class I or class II molecules expressed by APCs. The first signal secures the antigen specificity of the immune reaction. The second signal is transmitted through costimulatory receptors, dictating the progression to T cell activation. Between

In invertebrates, UNC-45 regulates myosin stability and functions. Vertebrates have two distinct isoforms of the protein: UNC-45B, expressed in muscle cells only and UNC-45A, expressed in all cells and implicated in regulating both Non-Muscle Myosin II (NMII)- and microtubule (MT)-associated functions. Here we show that both, in vitro and in cells, UNC-45A binds to the MT lattice leading to MT bending, breakage and depolymerization. Furthermore, we show that UNC-45A destabilizes MTs independent of its NMII C-terminal binding domain and even in presence of the NMII inhibitor blebbistatin. These findings identified UNC-45A as a novel type of MT-severing protein with a not mutually exclusive but rather dual role in regulating NMII activity and MT stability. Because many human diseases, from cancer to neurodegenerative diseases, are caused by or associated with deregulation of MT stability our findings have profound implications in both, the biology of MTs as well as the biology of human diseases and possible therapeutic implications for their treatment.

No abstract

Anoikis is a form of apoptosis induced by cell detachment. Integrin inactivation plays a major role in the process but the exact signalling pathway is ill-defined. Here we identify an anoikis pathway using gliotoxin (GT), a virulence factor of the fungus Aspergillus fumigatus, which causes invasive aspergillosis in humans. GT prevents integrin binding to RGD-containing extracellular matrix components by covalently modifying cysteines in the binding pocket. As a consequence, focal adhesion kinase (FAK) is inhibited resulting in dephosphorylation of p190RhoGAP, allowing activation of RhoA. Sequential activation of ROCK, MKK4/MKK7 and JNK then triggers pro-apoptotic phosphorylation of Bim. Cells in suspension or lacking integrin surface expression are insensitive to GT but are sensitised to ROCK-MKK4/MKK7-JNK-dependent anoikis upon attachment to fibronectin or integrin upregulation. The same signalling pathway is triggered by FAK inhibition or inhibiting integrin αV/β3 with Cilengitide. Thus, GT can target integrins to induce anoikis on lung epithelial cells.

Graphical abstract

The utilization of phenol, m-toluate, and salicylate (Phe+, mTol+, and Sal' characters, respectively) in Pseudomonas sp. strain EST1001 is determined by the coordinated expression of genes placed in different plasmids, i.e., by a multiplasmid system. The natural multiplasmid strain EST1001 is phenotypically unstable.In its Phe-, mTol-, and Sal-segregants, the plasmid DNA underwent structural rearrangements without a marked loss of plasmid DNA, and the majority of segregants gave revertants. The genes specifying the degradation of phenol and m-toluate were transferable to P. putida PaW340, and in this strain a new multiplasmid system with definite structural changes was formed. The 17-kilobase transposable element, a part of the TOL plasmid pWWO present in the chromosome of PaW340, was inserted into the plasmid DNA in transconjugants. In addition, transconjugant EST1020 shared pWWO-like structures. Enzyme assays demonstrated that ortho-fission reactions were used by bacteria that grew on phenol, whereas m-toluate was catabolized by a meta-fission reaction. Salicylate was a functional inducer of the enzymes of both pathways. The expression of silent metabolic pathways of phenol or m-toluate degradation has been observed in EST1001 PhemTol+ and Phe+ mTol-transconjugants. The switchover of phenol degradation from the ortho-to the meta-pathway in EST1033 also showed the flexibility of genetic material in EST1001 transconjugants.