5 research outputs found
Mechanism of the Regulation of Organic Cation/Carnitine Transporter 1 (SLC22A4) by Rheumatoid Arthritis-Associated Transcriptional Factor RUNX1 and Inflammatory Cytokines
ABSTRACT: Recently, it was reported that the organic cation/carnitine transporter 1 (OCTN1, SLC22A4) is associated with chronic inflammatory diseases, such as rheumatoid arthritis (RA) and Crohn's disease. OCTN1 in humans is expressed in synovial tissues of individuals with rheumatoid arthritis. Furthermore octn1 in mice is expressed in inflamed joints with collagen-induced arthritis, a model of human arthritis, but not in the joints of normal mice. OCTN1 should be involved in the inflammatory disease and in the present study, the regulatory mechanism of OCTN1 expression was characterized using the human fibroblast-like synoviocyte cell line MH7A, derived from RA patients. A luciferase-reporter gene assay and gel shift assay demonstrated that RUNX1, which is an essential hematopoietic transcription factor associated with acute myeloid leukemia and is related to RA and Sp1, is involved in the regulation of OCTN1 promoter activity. Inflammatory cytokines such as interleukin-1ā¤ and tumor necrosis factor-ā£ increased the expression of OCTN1 mRNA. Furthermore, overexpression of nuclear factor-B (NF-B) activated promoter activity of OCTN1. These results clearly demonstrate that expression of OCTN1 is regulated by various factors, including RUNX1, inflammatory cytokines, and NF-B, all of which are also related to the pathogenesis of RA. Further studies on the physiological substrate(s) of OCTN1 should be done to clarify the roles of OCTN1 in these diseases
Abbreviated BioBrick Prefix and Suffix for More Efficient Primer Design
This Request for Comments (RFC) modifies the assembly standard for biological parts proposed in BBF RFC 10 by removing the NotI restriction site from the BioBrick Prefix and Suffix
Fe(II) Ion Release during Endocytotic Uptake of Iron Visualized by a Membrane-Anchoring Fe(II) Fluorescent Probe
Iron is an essential transition metal
species for all living organisms and plays various physiologically
important roles on the basis of its redox activity; accordingly, the
disruption of iron homeostasis triggers oxidative stress and cellular
damage. Therefore, cells have developed sophisticated iron-uptake
machinery to acquire iron while protecting cells from uncontrolled
oxidative damage during the uptake process. To examine the detailed
mechanism of iron uptake while controlling the redox status, it is
necessary to develop useful methods with redox state selectivity,
sensitivity, and organelle specificity to monitor labile iron, which
is weakly bound to subcellular ligands. Here, we report the development
of Mem-RhoNox to monitor local FeĀ(II) at the surface of the plasma
membrane of living cells. The redox state-selective fluorescence response
of the probe relies on our recently developed <i>N</i>-oxide
strategy, which is applicable to fluorophores with dialkylarylamine
in their Ļ-conjugation systems. Mem-RhoNox consists of the <i>N</i>-oxygenated rhodamine scaffold, which has two arms, both
of which are tethered with palmitoyl groups as membrane-anchoring
domains. In an aqueous buffer, Ac-RhoNox, a model compound of Mem-RhoNox,
shows a fluorescence turn-on response to the FeĀ(II) redox state-selectively.
An imaging study with Mem-RhoNox and its derivatives reveals that
labile FeĀ(II) is transiently generated during the major iron-uptake
pathways: endocytotic uptake and direct transport. Furthermore, Mem-RhoNox
is capable of monitoring endosomal FeĀ(II) in primary cultured neurons
during endocytotic uptake. This report is the first example that identifies
the generation of FeĀ(II) over the course of cellular iron-uptake processes