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Primary kidney macrophage (PKM) cultures derived from goldfish hematopoietic tissues develop from early progenitors to mature macrophages in response to endogenous growth factor(s). When grown in vitro, PKM shift from a proliferative phase, where most of the proliferation and differentiation events take place, to a senescence phase, where there is cessation of proliferation and differentiation events and ultimately cell death through a process of apoptosis. The phenotypic changes of PKM from the proliferative to senescence phase are a reflection of specific changes in gene expression; therefore, comparison of gene expression patterns between the two phases should lead to the identification of macrophage genes directly involved in the positive and negative regulation of hematopoietic events, as well as genes that are modulated downstream from these regulatory points. Differential cross-screening of the proliferative phase PKM cDNA library using proliferative and senescence phase 32P-labeled cDNA probes identified several differentially expressed genes. Specifically, initial screen of 9200 clones yielded 734 differential primary clones that were isolated and analyzed using a PCR-based secondary screen. The majority of these clone isolates encoded a single transcript as determined by PCR amplification of the primary clones. The secondary screen confirmed the differential expression of 306 clones (3.32% of the total number of screened clones). Two hundred and forty four clones were sequenced; 158 and 86 were preferentially expressed during proliferative and senescence phases, respectively. Several potential candidates of fish macrophage hematopoiesis were identified. These include, for example, zinc finger protein 147, nucleophosmin, 14-3-3 protein, adenine nucleotide translocator 2 (ANT2), granulin, survivin-1, and apoptosis inhibitor-5. In addition, several potential markers of macrophage differentiation and/or function were identified and their expression patterns characterized across three distinct stages of macrophage development in vitro. These include legumain, CD63, interferon-inducible protein, macrosialin (CD68), transcription factor MafB, and the molecular chaperone BiP/GRP78. These analyses will facilitate future characterization of macrophage developmental events by providing a more global perspective of various facets of macrophage hematopoiesis. [Copyright &y& Elsevier]

Interleukin-6 (IL-6) production is up-regulated by several stimuli through the activation of transcription factors. We have previously demonstrated that CCAAT/enhancer binding protein homologous protein (CHOP) positively regulates IL-6 production at the transcriptional level in the human melanoma cell line A375. In this study, we provide evidence that CHOP up-regulates the IL-6 transcription without binding to the IL-6 promoter. CHOP dimerized more preferentially with an inhibitory isoform of nuclear factor for IL-6 expression (LIP (liver-enriched inhibitory protein)) than with a positively acting isoform (LAP, liver-enriched activator protein). These results indicate that CHOP plays an important role in IL-6 production without binding to its promoter, probably by trapping protein(s) such as LIP, which would otherwise inhibit IL-6 transcription. [Copyright &y& Elsevier]

Interleukin (IL)-1 modulates the expression of various genes in normal and tumor cells. We investigated the molecular mechanisms underlying IL-1β-induced expression of IL-8 mRNA and protein in human vascular smooth muscle cells (hVSMCs). P38 mitogen-activated protein kinase (MAPK) was activated after 5 min of IL-1β treatment, whereas the extracellular signal-regulated kinases, the c-jun amino-terminal kinases, and protein kinase B/Akt were not activated by IL-1β. IL-1β induced activation of a full-length IL-8 promoter–reporter construct. Deletional mutagenesis localized the IL-1β-responsive domains to two regions (−133 to −98 and −85 to −50) that contain consensus binding sites for activator protein-1 (AP-1) and nuclear factor-κB (NF-κB), respectively. Site-directed mutagenesis of the 133-bp minimal promoter confirmed that these sites were required for promoter activity. Electrophoretic mobility shift assays confirmed that IL-1β increased AP-1 and NF-κB DNA-binding activities in a time-dependent manner. SB203580, a specific P38 MAPK inhibitor, partially blocked IL-1β induction of IL-8 mRNA, IL-8 promoter activity, and AP-1 nuclear extract binding but not NF-κB DNA binding. Our data demonstrate that AP-1 and NF-κB are essential transcription factors for IL-1β-induced IL-8 gene expression in hVSMCs. P38 MAPK is involved in inducing IL-8 gene transcription via AP-1 activation in hVSMCs. [Copyright &y& Elsevier]