Yusho patients show increased serum IL-17, IL-23, IL-1β, and TNFα levels more than 40 years after accidental polychlorinated biphenyl poisoning

The Yusho poisoning incident, caused by rice oil contaminated with polychlorinated biphenyls (PCBs), polychlorinated quarterphenyls (PCQs), and polychlorinated dibenzofurans (PCDFs) generated by heat-denatured PCBs, occurred in 1968 in western Japan. Although severe symptoms are rarely observed today, the levels of PCBs and PCDFs in the sera of Yusho patients remain high. The aryl hydrocarbon receptor (AhR), which also acts as a dioxin receptor, is a transcriptional regulator that mediates dioxin toxicity. Recent studies show that dioxin mediates its immune toxic effects via AhR and that AhR activation induces dysregulation of interleukin (IL)-17-producing T (TH17) cells. This study therefore hypothesized that Yusho patients would show dysregulated TH17 cell-mediated immune responses. To validate the hypothesis, levels of IL-17 and IL-22, each secreted by TH17 cells, along with IL-1β and IL-23 were measured in serum samples from 40 Yusho patients and 40 age-matched controls. Levels of tumor necrosis factor (TNF)-α potentially secreted by TH17 cell-stimulated neutrophils and macrophages were also measured. The results indicated that serum IL-17 levels, as well as those of IL-1β, IL-23, and TNFα, were significantly higher in Yusho patients than in controls. In contrast, serum IL-22 levels were significantly lower in the Yusho patients. These results suggest that Yusho patients have dysregulated TH17 cell-mediated immune responses that may be linked to inflammation

miR-196a Downregulation Increases the Expression of Type I and III Collagens in Keloid Fibroblasts

Keloids are a fibroproliferative disease due to abnormal wound healing process after skin injury. They are characterized by overproduction of extracellular matrix (ECM) such as collagens. MicroRNAs (miRNAs) are noncoding small RNAs and negatively regulate protein expression. Several miRNAs that have critical roles in tissue fibrosis and ECM metabolism have been reported. However, regulation and function of miRNAs in keloid remain to be explored. The purpose of this study was to identify miRNAs involved in keloid pathogenesis. We performed miRNA microarray analysis to compare miRNA expression profiles between keloid-derived fibroblasts (KFs) and normal fibroblasts (NFs). In all, 7 upregulated and 20 downregulated miRNAs were identified. Among these, we focused on miR-196a, which showed the highest fold change. Overexpression or knockdown of miR-196a led to a decreased or increased level of secreted type I/III collagens, respectively. Reporter analysis showed direct binding of miR-196a to the 3′ untranslated region (UTR) of COL1A1 and COL3A1. In conclusion, we demonstrate for the first time that miRNA expression profile is altered in KFs compared with NFs. Downregulation of miR-196a may be one of the mechanisms by which collagens are highly deposited in keloid tissues. Our findings suggest that miR-196a could be a new therapeutic target for keloid lesions

Mutations in UVSSA cause UV-sensitive syndrome and impair RNA polymerase IIo processing in transcription-coupled nucleotide-excision repair

UV-sensitive syndrome (UVSS) is a genodermatosis characterized by cutaneous photosensitivity without skin carcinoma1, 2, 3, 4. Despite mild clinical features, cells from individuals with UVSS, like Cockayne syndrome cells, are very UV sensitive and are deficient in transcription-coupled nucleotide-excision repair (TC-NER)2, 4, 5, which removes DNA damage in actively transcribed genes6. Three of the seven known UVSS cases carry mutations in the Cockayne syndrome genes ERCC8 or ERCC6 (also known as CSA and CSB, respectively)7, 8. The remaining four individuals with UVSS, one of whom is described for the first time here, formed a separate UVSS-A complementation group1, 9, 10; however, the responsible gene was unknown. Using exome sequencing11, we determine that mutations in the UVSSA gene (formerly known as KIAA1530) cause UVSS-A. The UVSSA protein interacts with TC-NER machinery and stabilizes the ERCC6 complex; it also facilitates ubiquitination of RNA polymerase IIo stalled at DNA damage sites. Our findings provide mechanistic insights into the processing of stalled RNA polymerase and explain the different clinical features across these TC-NER–deficient disorders

Mechanism of laminin chain assembly into a triple-stranded coiled-coil structure

Laminin, a basement membrane glycoprotein, is a heterotrimer with alpha, beta, and gamma chains held together by a triple-stranded alpha-helical coiled-coil structure. Recently, a short peptide sequence at the C-terminus of the alpha-helical domain of each chain was identified as a critical site for the initiation of laminin chain assembly. Synthetic peptides, B1 and B2 (51-mers from the mouse laminin beta 1 and gamma 1 chains respectively) and M (55-mer from the laminin alpha 2 chain), containing these sites were able to assemble into a triple-stranded coiled-coil structure with chain-specific interactions [Nomizu, M., Otaka, A., Utani, A., Roller, P. P., & Yamada, Y. (1994) J. Biol. Chem. 269, 30386-30392]. Here we focus on the mechanism of laminin assembly and examine the conformation and stability of the peptides under various conditions using circular dichroism (CD) spectroscopy. Dependence on chain length for the conformation and stability of trimers suggests that 51-mers for laminin beta 1 and gamma 1 chains and a 55-mer for the laminin alpha 2 chain are critical to attain high thermal stability (T m = 62 degrees C), similar to the larger fragments (approximately 200-mers) and to intact laminins. Since the conformation and stability are dependent on pH and the B1 and B2 monomers and the B1-B2 dimer conformations are partially destroyed at neutral pH, it is likely that they contain intra- and/or interchain repulsions by acidic residues. Moreover, the B1-B2 dimer was significantly more stable under acidic conditions, while the B1-B2/M trimer appears to dissociate into separate B1-B2 and M peptides at pH 2. Urea-induced denaturation showed that the B1-B2/M was more stable than the B1-B2, while both complexes showed virtually identical guanidine hydrochloride denaturation curves. Our data indicate that ionic interactions between B1-B2 and M are critical for the specific trimer formation. We propose a mechanism for laminin assembly: (1) A heterodimer B1-B2 is preferentially formed and creates an acidic pocket which provides a less stable structure due to intra- and intermolecular repulsions between acidic amino acids. (2) A basic site in the M peptide interacts specifically with the acidic pocket of the B1-B2 dimer and results in assembly into a more stable triple-stranded coiled-coil structure