Tctp, a unique Ing5-binding partner, inhibits the chromatin binding of Enok in Drosophila.

The MOZ/MORF histone acetyltransferase complex is highly conserved in eukaryotes and controls transcription, development, and tumorigenesis. However, little is known about how its chromatin localization is regulated. Inhibitor of growth 5 (ING5) tumor suppressor is a subunit of the MOZ/MORF complex. Nevertheless, the in vivo function of ING5 remains unclear. Here, we report an antagonistic interaction between Drosophila Translationally controlled tumor protein (TCTP) (Tctp) and ING5 (Ing5) required for chromatin localization of the MOZ/MORF (Enok) complex and H3K23 acetylation. Yeast two-hybrid screening using Tctp identified Ing5 as a unique binding partner. In vivo, Ing5 controlled differentiation and down-regulated epidermal growth factor receptor signaling, whereas it is required in the Yorkie (Yki) pathway to determine organ size. Ing5 and Enok mutants promoted tumor-like tissue overgrowth when combined with uncontrolled Yki activity. Tctp depletion rescued the abnormal phenotypes of the Ing5 mutation and increased the nuclear translocation of Ing5 and chromatin binding of Enok. Nonfunctional Enok promoted the nuclear translocation of Ing5 by reducing Tctp, indicating a feedback mechanism between Tctp, Ing5, and Enok to regulate histone acetylation. Therefore, Tctp is essential for H3K23 acetylation by controlling the nuclear translocation of Ing5 and chromatin localization of Enok, providing insights into the roles of human TCTP and ING5-MOZ/MORF in tumorigenesis.

Effect of CCL5 on dimethylarginine dimethylaminohydrolase-1 production in vascular smooth muscle cells from spontaneously hypertensive rats.

Chemokines promote vascular inflammation and play a pathogenic role in the development and maintenance of hypertension. However, in our previous study, chemokine CCL5 was shown to reduce Ang II-induced 12-lipoxygenase (12-LO) production as well as proliferation in vascular smooth muscle cells (VSMCs) obtained from spontaneously hypertensive rats (SHR). Dimethylarginine dimethylaminohydrolase (DDAH) acts as an important regulator of vascular function by metabolizing and regulating plasma asymmetric (N(G),N(G)) dimethylarginine (ADMA), a major risk factor for cardiovascular disease. Therefore, in this study, we investigated the effect of CCL5 on DDAH-1 production in SHR VSMCs. Constitutive expression of DDAH-1 in VSMCs from SHR was higher than that in VSMCs from normotensive Wistar Kyoto rats (WKY), whereas expression of DDAH-2 was not significantly different between SHR and WKY VSMCs. CCL5 increased DDAH-1 production and attenuated Ang II-induced DDAH-1 inhibition in SHR VSMCs. In addition, although CCL5 did not affect the level of asymmetric (N(G),N(G)) dimethylarginine (ADMA), it attenuated Ang II-induced ADMA production through DDAH-1 activity. DDAH-1 induction by CCL5 was mediated by the Ang II subtype 2 receptor (AT2 R) pathway. Further, attenuation of Ang II-induced 12-LO and endothelin-1 (ET-1) expression by CCL5 could be attributed to DDAH-1 activity. These findings combined with our previous results suggest that CCL5 is a potential down-regulatory factor in Ang II-induced vascular hypertension.

Downregulation of Angiotensin II-Induced 12-Lipoxygenase Expression and Cell Proliferation in Vascular Smooth Muscle Cells from Spontaneously Hypertensive Rats by CCL5.

Angiotensin II (Ang II) plays an important role in vascular hypertension. The role of the chemokine CCL5 on Ang II-induced activities in vascular smooth muscle cells (VSMCs) has not been studied. In this study, we elucidated the effect of CCL5 on Ang II-induced 12-lipoxygenase (LO) expression and cell proliferation in spontaneously hypertensive rats (SHR) VSMCs. CCL5 decreased Ang II-induced 12-LO mRNA expression and protein production, and it increased Ang II type 2 (AT(2)) receptor expression in SHR VSMCs. The inhibitory effect of CCL5 on Ang II-induced 12-LO mRNA expression was mediated through the AT(2) receptor. Although treatment of CCL5 alone induced SHR VSMCs proliferation, CCL5 inhibited Ang II-induced VSMCs proliferation and PD123,319, an AT(2) receptor antagonist, blocked the inhibitory effect of CCL5 on Ang II-induced VSMCs proliferation. Phosphorylation of p38 was detected in VSMCs treated with Ang II or CCL5 alone. But, decrease of p38 phosphorylation was detected in VSMCs treated with Ang II and CCL5 simultaneously (Ang II/CCL5) and PD123,319 increased p38 phosphorylation in VSMCs treated with Ang II/CCL5. Therefore, these results suggest that the inhibitory effect of CCL5 on Ang II-induced VSMCs proliferation is mediated by the AT(2) receptor via p38 inactivation, and CCL5 may play a beneficial role in Ang II-induced vascular hypertension.

IL-8/CXCL8 Upregulates 12-Lipoxygenase Expression in Vascular Smooth Muscle Cells from Spontaneously Hypertensive Rats.

BACKGROUND: We previously demonstrated remarkable differences in the expression of IL-8/CXCL8 in aortic tissues and vascular smooth muscle cells (VSMC) from spontaneously hypertensive rats (SHR) compared to VSMC from normotensive Wistar-Kyoto rats (WKY). In the present study, we investigated the direct effect of IL-8/CXCL8 on expression of 12-lipoxygenase (LO), a hypertensive modulator, in SHR VSMC. METHODS: Cultured aortic VSMC from SHR and WKY were used. Expression of 12-LO mRNA was determined by real-time polymerase chain reaction. Phosphorlyation of ERK1/2 and production of 12-LO and angiotensin II subtype 1 (AT(1)) receptor were assessed by Western blots. IL-8/CXCL8-stimulated DNA synthesis was determined by measuring incorporation of [(3)H]-thymidine. And effect of IL-8/CXCL8 on vascular tone was determined by phenylephrine-induced contraction of thoracic aortic rings. RESULTS: Treatment with IL-8/CXCL8 greatly increased 12-LO mRNA expression and protein production compared to treatment with angiotensin II. IL-8/CXCL8 also increased the expression of the AT(1) receptor. The increase in 12-LO induced by IL-8/CXCL8 was inhibited by treatment with an AT(1) receptor antagonist. The induction of 12-LO mRNA production and the proliferation of SHR VSMC by IL-8/CXCL8 was mediated by the ERK pathway. The proliferation of SHR VSMC and the vascular contraction in the thoracic aortic ring, both of which were induced by IL-8/CXCL8, were inhibited by baicalein, a 12-LO inhibitor. CONCLUSION: These results suggest that the potential role of IL-8/CXCL8 in hypertensive processes is likely mediated through the 12-LO pathway.

15-Deoxy-Delta-Prostaglandin J(2) Upregulates the Expression of LPS-Induced IL-8/CXCL8 mRNA in Vascular Smooth Muscle Cells from Spontaneously Hypertensive Rats.

BACKGROUND: 15d-PGJ(2) has been known to act as an anti-inflammatory agent and has anti-hypertensive effects. As a result of these properties, we examined the effect of 15d-PGJ(2) on the LPS-induced IL-8/CXCL8 mRNA expression in VSMCs from SHR. METHODS: Effect and action mechanism of 15d-PGJ(2) on the expression of LPS-induced IL-8/CXCL8 mRNA in VSMCs from SHR and WKY were examined by using real-time polymerase chain reaction, electrophoretic mobility shift assay for NF-kappaB avtivity, Western blotting analysis for ERK and p38 phosphorylation and flow cytometry for NAD(P)H oxidase activity. RESULTS: 15d-PGJ(2) decreased the expression of LPS-induced IL-8/CXCL8 mRNA in WKY VSMCs, but increased the expression of LPS-induced IL-8/CXCL8 mRNA in SHR VSMCs. The upregulatory effect of 15d-PGJ(2) in SHR VSMCs was mediated through PPARgamma, and dependent on NF-kappaB activation and ERK phosphorylation. However, inhibition of the p38 signaling pathway augmented the upregulatory effect of 15d-PGJ(2) on LPS-induced IL-8/CXCL8 mRNA. A NAD(P)H oxidase inhibitor inhibited the upregulatory effect of 15d-PGJ(2) on LPS-induced IL-8/CXCL8 mRNA expression in SHR VSMCs, and an increase in NAD(P)H oxidase activity was detected in SHR VSMCs treated with 15d-PGJ(2)/LPS. CONCLUSION: Our results indicate that the upregulatory effect of 15d-PGJ(2) on LPS-induced IL-8/CXCL8 expression in SHR VSMCs is mediated through the PPARgamma and ERK pathway, and may be related to NAD(P)H oxidase activity. However, p38 inactivation may also play an important role in 15d-PGJ(2)/LPS-induced IL-8/CXCL8 expression in SHR VSMCs.