VEGF and thrombin induce MKP-1 through distinct signaling pathways: role for MKP-1 in endothelial cell migration

We have previously reported that MAPK phosphatase-1 (MKP-1/CL100) is a thrombin-responsive gene in endothelial cells (ECs). We now show that VEGF is another efficacious activator of MKP-1 expression in human umbilical vein ECs. VEGF-A and VEGF-E maximally induced MKP-1 expression in ECs; however, the other VEGF subtypes had no effect. Using specific neutralizing antibodies, we determined that VEGF induced MKP-1 specifically through VEGF receptor 2 (VEGFR-2), leading to the downstream activation of JNK. The VEGF-A(165) isoform stimulated MKP-1 expression, whereas the VEGF-A(162) isoform induced the gene to a lesser extent, and the VEGF-A(121) isoform had no effect. Furthermore, specific blocking antibodies against neuropilins, VEGFR-2 coreceptors, blocked MKP-1 induction. A Src kinase inhibitor (PP1) completely blocked both VEGF- and thrombin-induced MKP-1 expression. A dominant negative approach revealed that Src kinase was required for VEGF-induced MKP-1 expression, whereas Fyn kinase was critical for thrombin-induced MKP-1 expression. Moreover, VEGF-induced MKP-1 expression required JNK, whereas ERK was critical for thrombin-induced MKP-1 expression. In ECs treated with short interfering (si)RNA targeting MKP-1, JNK, ERK, and p38 phosphorylation were prolonged following VEGF stimulation. An ex vivo aortic angiogenesis assay revealed a reduction in VEGF- and thrombin-induced sprout outgrowth in segments from MKP-1-null mice versus wild-type controls. MKP-1 siRNA also significantly reduced VEGF-induced EC migration using a transwell assay system. Overall, these results demonstrate distinct MAPK signaling pathways for thrombin versus VEGF induction of MKP-1 in ECs and point to the importance of MKP-1 induction in VEGF-stimulated EC migration.     

Cytological studies of plasma albumin in the rat liver

Summary The presence of albumin in the parenchymal cells of the rat liver is demonstrated using the fluorescent antibody method. It is evident that there is no immunological difference between liver and blood albumin. The liver section is not uniformly stained by the fluorescent antibody and this may be due to the uneven distribution of albumin in the liver. A small percentage of the parenchymal cells presumably containing albumin are markedly fluorescent. The nuclei of these cells are not fluorescent implying the absence of albumin and this is consistent with the fact that nuclei are not involved in synthesis of albumin. The scattered distribution of brightly fluorescent cells confirms earlier observations that all parenchymal cells are not functionally alike, although they appear homogenous histologically.     

Alkaloids of Aconitum ferox

From the roots of Aconitum ferox four alkaloids have been isolated. Pseudaconitine is the major constituent and the other three minor alkaloids are identified as bikhaconitine, veratroyl pseudaconine and diacetyl pseudaconitine. Veratroyl pseudaconine and diacetyl pseudaconitine have not been previously found in nature.     

Treatment with TNF-α or bacterial lipopolysaccharide attenuates endocardial endothelial cell-mediated stimulation of cardiac fibroblasts

Background

The endocardial endothelium that lines the inner cavity of the heart is distinct from the microvascular endothelial cells and modulates cardiac muscle performance in a manner similar to the vascular endothelial modulation of vascular structure and vasomotor tone. Although the modulatory effects of endocardial endothelium (EE) on cardiomyocytes are firmly established, the regulatory effects of endocardial endothelium on the cardiac interstitium and its cellular components remain ill defined.

Methods and Results

We investigated whether the stimulatory effect of EE on cardiac fibroblasts would be altered when EECs are activated by the cytokine tumor necrosis factor-α (TNF-α) or the endotoxin bacterial lipopolysaccharide (LPS). Both TNF-α and LPS were found to independently attenuate the stimulatory effect of EE on cardiac fibroblasts. These agents lowered the synthesis or release of ET-1 and increased the secretion of TGF-β and NO.

Conclusion

The findings of this study using endocardial endothelial cells (EECs) and neonatal cardiac fibroblasts demonstrate that pro-inflammatory cytokines cause altered secretion of paracrine factors by EECs and inhibit proliferation and lower collagen synthesis in fibroblasts. These changes may influence fibroblast response and extra cellular matrix remodeling in pathological conditions of the heart.     

Cellular radioprotecting potential of glyzyrrhizic acid, silver nanoparticle and their complex

Silver nanoparticles (SN) of particle size of less than 50nm were redispersed in aqueous solution of Pluronic F127 and complexed with the phytoceutical, glyzyrrhizic acid (GLY). Radioprotecting ability of the obtained nanoparticle-glyzyrrhizic acid complex (SN-GLY) was evaluated in an in vivo model using Swiss albino mice. Oral administration of SN-GLY, SN and GLY one hour prior to radiation exposure reduced the radiation induced damage in peripheral blood leucocytes, bone marrow cells and spleen cells of mice as revealed by comet assay. Exposure of mice to whole body gamma irradiation resulted in formation of micronuclei in blood reticulocytes and chromosomal aberrations in bone marrow cells while SN-GLY, SN or GLY administration resulted in reduction in micronucleus formation and chromosomal aberrations indicating radioprotection. In SN-GLY treated mice the cellular DNA was found protected to a greater extent compared to GLY or SN treated mice. The studies, under in vivo radiation exposure conditions, showed effective radiation protection.     

The Making of the Women in Biology Forum (WiB) at Bioclues

The Women in Biology forum (WiB) of Bioclues (India) began in 2009 to promote and support women pursuing careers in bioinformatics and computational biology. WiB was formed in order to help women scientists deprived of basic research, boost the prominence of women scientists particularly from developing countries, and bridge the gender gap to innovation. WiB has also served as a platform to highlight the work of established female scientists in these fields. Several award-winning women researchers have shared their experiences and provided valuable suggestions to WiB. Headed by Mohanalatha Chandrasekharan and supported by Dr. Reeta Rani Singhania and Renuka Suravajhala, WiB has seen major progress in the last couple of years particularly in the two avenues Mentoring and Research, off the four avenues in Bioclues: Mentoring, Outreach, Research and Entrepreneurship (MORE).In line with the Bioclues vision for bioinformatics in India, the WiB Journal Club (JoC) recognizes women scientists working on functional genomics and bioinformatics, and provides scientific mentorship and support for project design and hypothesis formulation. As a part of Bioclues, WiB members practice the group''s open-desk policy and its belief that all members are free to express their own thoughts and opinions. The WiB forum appreciates suggestions and welcomes scientists from around the world to be a part of their mission to encourage women to pursue computational biology and bioinformatics.