CD163-L1 is an endocytic macrophage protein strongly regulated by mediators in the inflammatory response

CD163-L1 belongs to the group B scavenger receptor cysteine-rich family of proteins, where the CD163-L1 gene arose by duplication of the gene encoding the hemoglobin scavenger receptor CD163 in late evolution. The current data demonstrate that CD163-L1 is highly expressed and colocalizes with CD163 on large subsets of macrophages, but in contrast to CD163 the expression is low or absent in monocytes and in alveolar macrophages, glia, and Kupffer cells. The expression of CD163-L1 increases when cultured monocytes are M-CSF stimulated to macrophages, and the expression is further increased by the acute-phase mediator IL-6 and the anti-inflammatory mediator IL-10 but is suppressed by the proinflammatory mediators IL-4, IL-13, TNF-α, and LPS/IFN-γ. Furthermore, we show that CD163-L1 is an endocytic receptor, which internalizes independently of cross-linking through a clathrin-mediated pathway. Two cytoplasmic splice variants of CD163-L1 are differentially expressed and have different subcellular distribution patterns. Despite its many similarities to CD163, CD163-L1 does not possess measurable affinity for CD163 ligands such as the haptoglobin-hemoglobin complex or various bacteria. In conclusion, CD163-L1 exhibits similarity to CD163 in terms of structure and regulated expression in cultured monocytes but shows clear differences compared with the known CD163 ligand preferences and expression pattern in the pool of tissue macrophages. We postulate that CD163-L1 functions as a scavenger receptor for one or several ligands that might have a role in resolution of inflammation.     

The acyl-CoA thioesterase I is regulated by PPARalpha and HNF4alpha via a distal response element in the promoter

The cytosolic acyl-coenzyme A thioesterase I (Acot1) is an enzyme that hydrolyzes long-chain acyl-CoAs of C(12)-C(20)-CoA in chain length to the free fatty acid and CoA. Acot1 was shown previously to be strongly upregulated at the mRNA and protein level in rodents by fibrates. In this study, we show that Acot1 mRNA levels were increased by 90-fold in liver by treatment with Wy-14,643 and that Acot1 mRNA was also increased by 15-fold in the liver of hepatocyte nuclear factor 4alpha (HNF4alpha) knockout animals. Our study identified a direct repeat 1 (DR1) located in the Acot1 gene promoter in mouse, which binds the peroxisome proliferator-activated receptor alpha (PPARalpha) and HNF4alpha. Chromatin immunoprecipitation (ChIP) assay showed that the identified DR1 bound PPARalpha/retinoid X receptor alpha (RXRalpha) and HNF4alpha, whereas the binding in ChIP was abrogated in the PPARalpha and HNF4alpha knockout mouse models. Reporter gene assays showed activation of the Acot1 promoter in cells by the PPARalpha agonist Wy-14,643 after cotransfection with PPARalpha/RXRalpha. However, transfection with a plasmid containing HNF4alpha also resulted in an increase in promoter activity. Together, these data show that Acot1 is under regulation by an interplay between HNF4alpha and PPARalpha.     

Human beta-interferon gene expression is regulated by an inducible enhancer element

We have localized the regulatory sequence required for viral or poly(I)-poly(C) activation of human beta-interferon gene expression to a region located between -37 and -77 from the mRNA cap site. This sequence has the characteristics of an inducible enhancer element: it can act upstream or downstream of the beta-interferon gene regardless of its orientation, and at distances up to approximately 1 kilobase from its normal location. Moreover, this element can confer inducibility on a heterologous promoter. Further analysis has identified a minimal regulatory element of 14 base pairs within this enhancer. Sequences closely related to this element are present five times within the 5'-flanking regions of both the alpha- and beta-interferon genes. The number of these minimal regulatory elements required for maximal beta-interferon gene expression appears to differ in different cell lines.     

Novel aminopeptidase N (APN/CD13) inhibitors derived from chloramphenicol amine

Aminopeptidase N (APN) is involved in different physiological and pathological processes of tumor cells, including proliferation, invasion, apoptosis and metastasis. Herein one series of compounds derived from commercially available (1S,2S)-2-amino-1-(4-nitrophenyl) propane-1,3-diol have been designed and synthesized. Furthermore, preliminary activity evaluation showed that some compounds elicited moderate inhibitory activity against APN with compounds 10e (IC(50)=6.1±0.5 μM) possessing the best efficacy, which could be used as the lead compound in the future for anticancer agents research.