Structural features of the human C3 gene: intron/exon organization, transcriptional start site, and promoter region sequence.
ABSTRACT The third component of human complement (C3) is a key molecule in the activation of the complement cascade. C3 cDNA fragments were used to identify seven cosmid clones that covered all but 1 kilobase pair (kb) of the C3 gene. The remainder of the gene was cloned by using the polymerase chain reaction. These clones were used to identify the intron/exon boundaries and to map the gene. The C3 gene is 42 kb in length and comprises 41 exons ranging in size from 52 to 213 base pairs (bp). The transcription start site was identified by primer extension, and approximately 1 kb of DNA upstream of this site was sequenced. Putative TATA and CAAT boxes were identified along with a number of regions that shared homology with known regulatory sequences. These include responsive elements for interferon-gamma, interleukin-6, nuclear factor kappa B, estrogen, glucocorticoids and thyroid hormone. Several of these agents have been shown to affect C3 synthesis and mRNA levels. The sizes of the exons in C3 were compared to those of C4 and alpha 2-macroglobulin (alpha 2M). Thirty-nine of 41 exons in C4 were found to be of similar size to the analogous ones in C3, and two-thirds of those in alpha 2M were also similarly sized, supporting the hypothesis that these genes arose from a common ancestor.
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ABSTRACT: Once thought of as purely the body's chief energy store, adipose tissue and its constituent adipocytes have emerged as both a metabolic entity and an endocrine one. Complement is generally thought of as originating mainly from hepatic synthesis but also from synthesis by the macrophage phagocyte system. This review revisits early descriptions of adipocytic synthesis of complement components and highlights the need of a systematic analysis of the contribution of adipose tissue to systemic inflammation in order to appreciate the immunological activity of this tissue.Molecular Immunology 11/2008; 46(5):755-60. DOI:10.1016/j.molimm.2008.09.013 · 3.00 Impact Factor
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ABSTRACT: Phytohormones and chemical compounds revealing estrogenic effects are of increasing interest for their possible influence on the physiology of the reproductive tract. The gap junction connexin (Cx) genes Cx26 and Cx43, the plasma glycoprotein clusterin gene and the complement C3 gene are highly regulated by estrogen in rat endometrium. To test the value of these genes as markers for estrogenic responsiveness we analyzed the effects of estradiol, diethylstilbestrol, the selective estrogen receptor modulators (SERMs) raloxifene and tamoxifen, the phytoestrogens genistein and daidzein, and the industrial compounds DDT (1,1,1-trichloro-2-(2-chlorophenyl)-2-(4-chlorophenyl) ethane) and polychlorinated biphenyl (PCB) on the transcription of these genes in rat endometrium in vivo. Enhancement of Cx26 and decrease of clusterin transcripts expression by estradiol was observed at 0.03 micro g/250 g body weight (BW), and induction of C3 expression was observed at 0.05 micro g/250 g BW. A comparable effect was obtained by a tenfold higher concentration of diethylstilbestrol. Tamoxifen had a regulatory effect on this set of genes at about a 300-fold higher concentration, while raloxifen revealed much weaker estrogenic activity. No effect on Cx43 transcripts was observed with any of the compounds at the concentrations used. An effect of genistein was observed only on Cx26 expression, while PCB decreased clusterin transcripts. These results show that Cx26, C3 and clusterin reveal a comparable sensitivity to estrogens and SERMs. With respect to the phytoestrogen genistein, however, Cx26 seems to be the most sensitive gene. The analysis of clusters of estrogen-sensitive endometrial genes could help to identify estrogenic substances, assess their potency, and elucidate their mechanism of action.Journal of Molecular Endocrinology 11/2002; 29(2):239-49. · 3.62 Impact Factor