Angiotensin II-induced smooth muscle cell migration is mediated by LDL receptor-related protein 1 via regulation of matrix metalloproteinase 2 expression

Angiotensin II (Ang II), one of the main vasoactive hormones of the renin-angiotensin system, contributes to the development and progression of atherosclerosis by inducing vascular smooth muscle cells (VSMCs) migration. Although previous studies have shown that Ang II upregulates low density lipoprotein receptor-related protein 1 (LRP1) expression in VSMCs and increases VSMCs migration, the role of LRP1 in Ang II-induced VSMCs migration remains unclear. Here, we reveal a novel mechanism by which LRP1 induces the expression of matrix metalloproteinase 2 (MMP2) and thereby promotes the migration of rat aortic SMCs (RAoSMCs). Knockdown of LRP1 expression greatly decreased RAoSMCs migration, which was rescued by forced expression of a functional LRP1 minireceptor, suggesting that LRP1 is a key regulator of Ang II-induced RAoSMCs migration. Inhibition of ligand binding to LRP1 by the specific antagonist receptor-associated protein (RAP) also led to reduced RAoSMCs migration. Because MMPs play critical roles in RAoSMCs migration, we examined the expression of several MMPs and found that the expression of functional MMP2 was selectively increased by Ang II treatment and decreased in LRP1-knockdown RAoSMCs. More interestingly, reduced MMP2 expression in LRP1-knockdown cells was completely rescued by exogenous expression of mLRP4, suggesting that MMP2 is a downstream regulator of LRP1 in Ang II-induced RAoSMCs migration. Together, our data strongly suggest that LRP1 promotes the migration of RAoSMCs by regulating the expression and function of MMP2.     

Evidence that the C‐terminal domain (CtD) autoinhibits neural repression by Drosophila E(spl)M8

Analysis of the retinal defects of a CK2 phosphomimetic variant of E(spl)M8 (M8S¹⁵⁹D) and the truncated protein M8* encoded by the E(spl)D allele, suggest that the nonphosphorylated CtD “autoinhibits” repression. We have investigated this model by testing for inhibition (in “trans”) by the CtD fragment in its nonphosphorylated (M8‐CtD) and phosphomimetic (M8SD‐CtD) states. In N⁺ flies, ectopic M8‐CtD compromises lateral inhibition, i.e., elicits supernumerary bristles as with loss of N signaling. This antimorphic activity of M8‐CtD strongly rescues the reduced eye and/or bristle loss phenotypes that are elicited by ectopic M8SD or wild type M8. Additionally, the severely reduced eye of N^spl/Y; E(spl)D/+ flies is also rescued by M8‐CtD. Rescue is specific to the time and place, the morphogenetic furrow, where “founding” R8 photoreceptors are specified. In contrast, the phosphomimetic M8SD‐CtD that is predicted to be deficient for autoinhibition, exhibits significantly attenuated or negligible activity. These studies provide evidence that autoinhibition by the CtD regulates M8 activity in a phosphorylation‐dependent manner. genesis 48:44–55, 2010. © 2009 Wiley‐Liss, Inc.     

FoxP3+ T cells undergo conventional first switch to lymphoid tissue homing receptors in thymus but accelerated second switch to nonlymphoid tissue homing receptors in secondary lymphoid tissues

Forkhead box P3 (FoxP3)-positive T cells are a specialized T cell subset for immune regulation and tolerance. We investigated the trafficking receptor switches of FoxP3(+) T cells in thymus and secondary lymphoid tissues and the functional consequences of these switches in migration. We found that FoxP3(+) T cells undergo two discrete developmental switches in trafficking receptors to migrate from primary to secondary and then to nonlymphoid tissues in a manner similar to conventional CD4(+) T cells as well as unique to the FoxP3(+) cell lineage. In the thymus, precursors of FoxP3(+) cells undergo the first trafficking receptor switch (CCR8/CCR9-->CXCR4-->CCR7), generating mostly homogeneous CD62L(+)CCR7(+)CXCR4(low)FoxP3(+) T cells. CXCR4 expression is regained in FoxP3(+) thymic emigrants in the periphery. Consistent with this switch, recent FoxP3(+) thymic emigrants migrate exclusively to secondary lymphoid tissues but poorly to nonlymphoid tissues. The FoxP3(+) thymic emigrants undergo the second switch in trafficking receptors for migration to nonlymphoid tissues upon Ag priming. This second switch involves down-regulation of CCR7 and CXCR4 but up-regulation of a number of memory/effector type homing receptors, resulting in generation of heterogeneous FoxP3(+) T cell subsets expressing various combinations of trafficking receptors including CCR2, CCR4, CCR6, CCR8, and CCR9. A notable difference between the FoxP3(+) and FoxP3(-) T cell populations is that FoxP3(+) T cells undergo the second homing receptor switch at a highly accelerated rate compared with FoxP3(-) T cells, generating FoxP3(+) T cells with unconventionally efficient migratory capacity to major nonlymphoid tissues.     

Heat shock augments myosin phosphatase target-subunit phosphorylation

Our previous study demonstrated that heat shock augmented vascular contraction. In the present study, we hypothesized that heat shock augments myosin phosphatase target-subunit (MYPT1) phosphorylation resulting in augmented vascular contraction. Endothelium-denuded rat aortic rings were mounted in organ baths, exposed to heat shock (42 degrees C for 45 min), and subjected to contraction 4 h after the heat shock followed by Western blot analysis for MLC(20) (the 20 kDa light chains of myosin II) or MYPT1. The contractile responses in both control and heat shock-treated aorta were inhibited by Y27632, an inhibitor of Rho-kinase. The level of the MLC(20) and MYPT1(Thr855) phosphorylation in response to KCl was higher in heat shock-treated aorta than that in timed-control. The increased MYPT1(Thr855) phosphorylation was inhibited by Y27632 (1.0 microM) in parallel with inhibition of MLC(20) phosphorylation and vascular contraction. These results indicate that heat shock augments MYPT1 phosphorylation resulting in augmented vascular contraction.     

Continuous infusion of PGE2 is catabolic with a negative bone balance on both cancellous and cortical bone in rats

It is well documented that intermittent PGE(2) treatment increases both trabecular and cortical bone mass. However, the effects of continuous PGE(2) administration remain undocumented. The aim of the study was to investigate the effects of continuous prostaglandin E(2) (PGE(2)) on different bone sites in skeletally mature rats. Six-month-old Sprague Dawley rats were treated with PGE(2) at 1 or 3 mg/kg/d continuously via infusion pump for 21 days. Two other groups of rats received PGE(2) at the same doses by intermittent (daily) subcutaneous injections and served as positive controls. Histomorphometry was performed on cancellous bone of the proximal tibial metaphysis and cortical bone of the tibial shaft. As expected, intermittent PGE(2) treatment increased both cancellous and cortical bone mass by stimulating bone formation at the cancellous, periosteal and endocortical bone surfaces. In contrast, continuous PGE(2) treatment decreased cancellous bone mass with bone resorption exceeding bone formation. In addition, continuous PGE(2) treatment increased endocortical and intracortical bone remodeling, inducing bone loss which was partially offset by stimulating periosteal expansion. We conclude that continuous PGE(2) treatment induces overall catabolic effects on both cancellous and cortical bone envelopes, which differs from intermittent PGE(2) treatment that is anabolic. Lastly, we speculate that superior bone mass may be achieved by co-treatment of continuous PGE(2) in combination with an anti-catabolic agent.     

Identification and functional analysis of vibrio vulnificus SmcR, a novel global regulator

Recently, quorum sensing has been implicated as an important global regulator controlling the production of numerous virulence factors such as capsular polysaccharides in bacterial pathogens. The nucleotide and deduced amino acid sequences of smcR, a homolog of V. harveyi luxR identified from V. vulnificus ATCC29307, were analyzed. The amino acid sequence of SmcR from V. vulnificus was 72 to 92% similar to those of LuxR homologs from Vibrio spp. Functions of SmcR were assessed by the construction of an isogenic mutant, whose smcR gene was inactivated by allelic exchanges, and by evaluating its phenotype changes in vitro and in mice. The disruption of smcR resulted in a significant alteration in biofilm formation, in type of colony morphology, and in motility. When compared with the wild-type, the smcR mutant exhibited reduced survival under adverse conditions, such as acidic pH and hyperosmotic stress. The smcR mutant exhibited decreased cytotoxic activity toward INT 407 cells in vitro. Furthermore, the intraperitoneal LD50 of the smcR mutant was approximately 10(2) times higher than that of parental wild-type. Therefore, it appears that SmcR is a novel global regulator, controlling numerous genes contributing to the pathogenesis as well as survival of V. vulnificus.     

Lipid-Overloaded Enlarged Adipocytes Provoke Insulin Resistance Independent of Inflammation

In obesity, adipocyte hypertrophy and proinflammatory responses are closely associated with the development of insulin resistance in adipose tissue. However, it is largely unknown whether adipocyte hypertrophy per se might be sufficient to provoke insulin resistance in obese adipose tissue. Here, we demonstrate that lipid-overloaded hypertrophic adipocytes are insulin resistant independent of adipocyte inflammation. Treatment with saturated or monounsaturated fatty acids resulted in adipocyte hypertrophy, but proinflammatory responses were observed only in adipocytes treated with saturated fatty acids. Regardless of adipocyte inflammation, hypertrophic adipocytes with large and unilocular lipid droplets exhibited impaired insulin-dependent glucose uptake, associated with defects in GLUT4 trafficking to the plasma membrane. Moreover, Toll-like receptor 4 mutant mice (C3H/HeJ) with high-fat-diet-induced obesity were not protected against insulin resistance, although they were resistant to adipose tissue inflammation. Together, our in vitro and in vivo data suggest that adipocyte hypertrophy alone may be crucial in causing insulin resistance in obesity.     

Association of CXCL10 and CXCL13 levels with disease activity and cutaneous manifestation in active adult-onset Still’s disease

IntroductionC-X-C motif chemokine 10 (CXCL10) is produced in response to interferon-γ, and tumor necrosis factor-α (TNF-α) triggers the accumulation of activated lymphocytes. CXCL13 is constitutively expressed in secondary lymphoid tissues, and the expression is upregulated by TNF-α, via T cell stimulation. It appears that CXCL10 and CXCL13 could play a potential role in the pathogenesis of adult-onset Still’s disease (AOSD), therefore, we investigated the associations between CXCL10 and CXCL13 levels and clinical manifestations in patients with active AOSD.MethodsBlood samples were collected from 39 active AOSD patients, 32 rheumatoid arthritis (RA) patients and 40 healthy controls (HC). Of the AOSD patients, follow-up samples were collected from 15 9.6 ± 9.2 months later. Serum levels of CXCL10 and CXCL13 were determined using enzyme-linked immunosorbent assay. CXCL10, CXCL13, and C-X-C chemokine receptor type 3 (CXCR3) expression levels in biopsy specimens obtained from 26 AOSD patients with skin rashes were investigated via immunohistochemistry.ResultsThe CXCL10 levels in AOSD patients (1,031.3 ± 2,019.6 pg/mL) were higher than in RA (146.3 ± 91.4 pg/mL, p = 0.008) and HC (104.4 ± 47.9 pg/mL, p = 0.006). Also, the CXCL13 levels of AOSD patients (158.8 ± 151.2 pg/mL) were higher than those of RA (54.4 ± 61.1 pg/mL, p < 0.001) and HC (23.5 ± 18.1 pg/mL, p < 0.001). Serum CXCL10 levels correlated with ferritin and systemic scores. Serum CXCL13 levels correlated with those of hemoglobin, C-reactive protein, ferritin, and albumin, and systemic scores. In follow-up AOSD patients, the levels of CXCL10 and CXCL13 fell significantly (153.7 ± 130.1 pg/mL, p = 0.002, and 89.1 ± 117.4 pg/mL, p = 0.001, respectively). On immunohistochemistry, the percentages of inflammatory cells expressing CXCL10 ranged from 1 to 85 %, CXCL13 from 1 to 72 %, and CXCR3 from 2 to 65 %. The percentage of CXCL10-positive inflammatory cells was higher in skin biopsy samples exhibiting mucin deposition than in those that did not (p = 0.01). CXCL13 levels were correlated with those of CD4 and CD68.ConclusionsSerum CXCL10 and CXCL13 levels may serve as clinical markers for assessment of disease activity in AOSD. CXCL10/CXCR3 and CXCL13 may contribute to the inflammatory response, especially skin manifestations thereof, in AOSD.

Electronic supplementary material

The online version of this article (doi:10.1186/s13075-015-0773-4) contains supplementary material, which is available to authorized users.