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Effects of methotrexate (MTX) on the proliferation of rheumatoid arthritis (RA) synovial fibroblasts are incompletely understood. We explored actions of MTX in view of circadian transcriptions of synovial fibroblasts. Under treatment with MTX, expression of core circadian clock genes, circadian transcriptional factor proline and acidic amino acid-rich basic leucine zipper (PAR bZIP), and proapoptotic molecule Bcl-2 interacting killer (Bik) was examined by real-time polymerase chain reaction. Protein expression of circadian clock gene PERIOD2 (PER2) and CYTOCHROME C was also examined by western blotting and ELISA. Promoter activities of Per2and Bikwere measured by Luciferase assay. Expression of PER2, BIK, and CYTOCHROME C and morphological changes of the nucleus were observed by fluorescent immunostaining. Synovial fibroblasts were transfected with Per2/Biksmall interfering RNA, and successively treated with MTX to determine cell viabilities. Finally, synovial fibroblasts were treated with MTX according to the oscillation of Per2/Bikexpression. MTX (10 nM) significantly decreased cell viabilities, but increased messenger RNA expression of Per2, Bik, and PAR ZIP including D site of the albumin promoter binding protein (Dbp), hepatic leukemia factor (Hlf), and thyrotroph embryonic factor (Tef). MTX also increased protein expression of PER2 and CYTOCHROME C, and promoter activities of Per2and Bik viaD-box. Under fluorescent observations, expression of PER2, BIK, and CYTOCHROME C was increased in apoptotic cells. Cytotoxicity of MTX was attenuated by silencing of Per2and/or Bik, and revealed that MTX was significantly effective in situations where Per2/Bikexpression was high. We present here novel unique action of MTX on synovial fibroblasts that upregulates PAR bZIP to transcribe Per2and Bik, resulting in apoptosis induction. MTX is important in modulating circadian environments to understand a new aspect of pathogenesis of RA.

Silane-coupling agents with 2-nitrobenzyl esters containing alkyl substituents at the benzyl position and alkoxy and/or fluoroalkoxy groups of the aromatic ring were synthesized to prepare a self-assembled monolayer (SAM) on quartz glass, silicon wafer and thermally oxidized silicon wafer. The resulting photosensitive SAMs before and after photoirradiation were characterized by contact angle measurement, UV spectroscopy, X-ray photoelectron spectroscopy (XPS), and X-ray reflectivity (XRR). Photosensitivity of the SAM was influenced by substituents at the benzyl position and aromatic ring as well as the irradiation conditions in air or solution and substrates employed. Silane-coupling agents with bulky substituent at the benzyl position and double fluoroalkoxy chains are preferable in terms of the photosensitivity and hydrophobic surface.