SCUBE1 (signal peptide-CUB-EGF domain-containing protein 1) is a novel, secreted, cell surface glycoprotein expressed during early embryogenesis and found in platelet and endothelial cells. This protein is composed of an N-terminal signal peptide sequence followed by nine tandemly arranged epidermal growth factor (EGF)-like repeats, a spacer region, three cysteine-rich repeat motifs, and one CUB domain at the C terminus. However, little is known about its domain and biological function. Here, we generated a comprehensive panel of domain deletion constructs and a new genetic mouse model with targeted disruption of Scube1 (Scube1 ⌬cub/⌬cub ) to investigate the domain function and biological significance. A number of cellbased assays were utilized to define the critical role of the spacer region for membrane association and establish that the EGFlike repeats 7-9 are sufficient for the formation of SCUBE1-mediated homophilic adhesions in a calcium-dependent fashion. Biochemical and molecular analyses showed that the C-terminal cysteine-rich motifs and CUB domain could directly bind and antagonize the bone morphogenetic protein activity. Furthermore, genetic ablation of this C-terminal region resulted in brain malformation in the Scube1 ⌬cub/⌬cub embryos.Together, our results support the dual roles of SCUBE1 on brain morphogenesis and cell-cell adhesions through its distinct domain function.SCUBE1 (signal peptide-CUB-EGF domain-containing protein 1) is the founding member of an evolutionarily conserved SCUBE gene family (1, 2). To date, three distinct isoforms have been cloned and named SCUBE1 to SCUBE3 according to their order of discovery in mammals (1-4). These genes coding for polypeptide molecules of about 1000 amino acids share an organized protein domain structure of at least 5 recognizable motifs: an N-terminal signal peptide sequence, 9 tandem repeats of epidermal growth factor (EGF) 3 -like modules, a large N-glycosylated spacer region followed by three repeated stretches of 6-cysteine residues with unique and regular spacing, and one CUB domain at the C terminus (see Fig. 1A). Our previous study demonstrated that the signal peptide sequence is sufficient to direct the expressed SCUBE1 protein into the secretory pathway and results in a secreted and surface-associated protein (1). However, little is known about the functional significance of the other four domains in SCUBE1.SCUBE genes have been shown to be expressed predominantly in a variety of developing tissues, including gonads, the central nervous system, dermomyotome, digital mesenchyme, and limb buds during mouse embryogenesis (2, 3, 5), which implies that the proteins may play important roles in development. However, direct functional studies of the roles of the SCUBE genes during mammalian development are still lacking. In addition to its embryonic expression, SCUBE1 was found to be expressed in the endothelium and platelets (1, 6). Our recent study showed that SCUBE1 is stored in the platelet ␣-granules and exposed to the cell surface upon platel...

Arachis hypogaea L.; peanut; groundnut; resveratrol; stilbenoids; arachidin; antioxidant; anti-inflammation.

Biological activities of peanut stilbenoids, mainly resveratrol and its derivatives, have attracted increased attention and interest because of peanut being a potent producer and a dietary channel to convey these polyphenols to the human body. As arachidin-1 and piceatannol are structurally close to resveratrol, it is worthy to investigate their immunological activities on inhibition of lipopolysaccharide (LPS)-induced production of PGE2 and NO and mediation of the related transcription factors (NF-kappaB and C/EBP) of RAW 264.7 macrophage cells. Productions of PGE2 and NO were inhibited by all the test stilbenoids in a dose-dependent manner while gene and protein expressions of COX-2 and iNOS were not inhibited. As shown by NF-kappaB-driven luciferase assay, LPS-induced NF-kappaB activities were also reduced by the stilbenoids. In further, when these stilbenoids were subjected to monitoring their inhibitory effectiveness on LPS-induced transcription factor expressions of C/EBPdelta and C/EBPbeta, only C/EBPdelta expressions were reduced. Thus, these stilbenoids were effective in inhibition of PGE2- or NO-mediated inflammation and NF-kappaB- or C/EBPdelta-mediated inflammatory gene expression. In comparison, the highest inhibitory activity on LPS-induced PGE2/NO production, C/EBPdelta gene expression, and NF-kappaB activation was piceatannol which was followed in order by arachidin-1 and resveratrol. The observed anti-inflammatory activities of these peanut stilbenoids are of merit in further consideration for nutraceutical applications.

The membrane forms of guanylyl cyclase (GC) serve as cell-surface receptors that synthesize the second messenger cGMP, which mediates diverse cellular processes. Rat kidney contains mRNA for the GC-G isoform, but the role of this receptor in health and disease has not been characterized. It was found that mouse kidney also contains GC-G mRNA, and immunohistochemistry identified GC-G protein in the epithelial cells of the proximal tubule and collecting ducts. Six hours after ischemia-reperfusion (I/R) injury, GC-G mRNA and protein expression increased three-fold and remained upregulated at 24 h. For determination of whether GC-G mediates I/R injury, a mutant mouse with a targeted disruption of the GC-G gene (Gucy2g) was created. At baseline, no histologic abnormalities were observed in GC-G Ϫ/Ϫ mice. After I/R injury, elevations in serum creatinine and urea were attenuated in GC-G Ϫ/Ϫ mice compared with wild-type controls, and this correlated with less tubular disruption, less tubular cell apoptosis, and less caspase-3 activation. Measures of inflammation (number of infiltrating neutrophils, myeloperoxidase activity, and induction of IL-6 and P-selectin) and activation of NF-B were lower in GC-G Ϫ/Ϫ mice compared with wild-type mice. Direct transfer of a GC-G expression plasmid to the kidneys of GC-G Ϫ/Ϫ mice resulted in a dramatically higher mortality after renal I/R injury, further supporting a role for GC-G in mediating injury. In summary, GC-G may act as an early signaling molecule that promotes apoptotic and inflammatory responses in I/R-induced acute renal injury.

Objective: The aim of this study was to investigate in a transgenic animal model the cardiac expression and function of a novel extracellular protein SCUBE3 [signal peptide-CUB (complement proteins C1r/C1s, Uegf, and Bmp1)-EGF (epidermal growth factor)-like domain-containing protein 3]. Methods and results: Real-time quantitative reverse transcriptase (RT)-PCR analysis showed that SCUBE3 is expressed in the ventricular myocardium. Male transgenic (TG) mice overexpressing SCUBE3 appeared normal during development, from birth to adulthood. However, echocardiography and histopathological examination revealed significant cardiac hypertrophy in TG animals as they aged, at 8 months. Interestingly, left-ventricle hypertrophy occurred more rapidly and more severely under pressure overload in TG mice, as compared to age-matched wild-type littermates. Induced SCUBE3 expression, together with elevated transforming growth factor (TGF)-β1 level under pressure overload, may account for the accelerated onset and progression of cardiac hypertrophy in TG mice. Furthermore, biochemical and molecular studies revealed that the carboxyl-terminal portion of SCUBE3 could physically interact with TGF-β1 and promote the TGF-β1-mediated transcriptional activation. Conclusion: This report is the first demonstration that SCUBE3 may play a role in the regulation of cardiac growth and remodeling responses, possibly through the stabilization of the TGF-β1 signaling pathway.