Heat shock protein 27 (HSP27) shows attenuated expression in human coronary arteries as the extent of atherosclerosis progresses. In mice, overexpression of HSP27 reduces atherogenesis, yet the precise mechanism (s) are incompletely understood. Inflammation plays a central role in atherogenesis, and of particular interest is the balance of pro-and anti-inflammatory factors produced by macrophages. As nuclear factor-kappa B (NF-κB) is a key immune signaling modulator in atherogenesis, and macrophages are known to secrete HSP27, we sought to determine if recombinant HSP27 (rHSP27) alters NF-κB signaling in macrophages. Treatment of THP-1 macrophages with rHSP27 resulted in the degradation of an inhibitor of NF-κB, IκBα, nuclear translocation of the NF-κB p65 subunit, and increased NF-κB transcriptional activity. Treatment of THP-1 macrophages with rHSP27 yielded increased expression of a variety of genes, including the pro-inflammatory factors, IL-1β, and TNF-α. However, rHSP27 also increased the expression of the anti-inflammatory factors IL-10 and GM-CSF both at the mRNA and protein levels. Our study suggests that in macrophages, activation of NF-κB signaling by rHSP27 is associated with upregulated expression and secretion of key pro-and anti-inflammatory cytokines. Moreover, we surmise that it is the balance in expression of these mediators and antagonists of inflammation, and hence atherogenesis, that yields a favorable net effect of HSP27 on the vessel wall.

Light-mediated seedling development is coordinately controlled by a variety of key regulators. Here, we identified two B-box (BBX)-containing proteins, BBX30 and BBX31, as repressors of photomorphogenesis. ELONGATED HYPOCOTYL5, a central regulator of light signaling, directly binds to the G-box cis-element present in the promoters of BBX30 and BBX31 and negatively controls their transcription levels in the light. Seedlings with mutations in BBX30 or BBX31 are hypersensitive to light, whereas the overexpression of BBX30 or BBX31 leads to hypo-photomorphogenic growth in the light. Furthermore, transgenic and phenotypic analysis revealed that the B-box domain of BBX30 or BBX31 is essential for their respective functioning in the regulation of photomorphogenic development in plants. In conclusion, BBX30 and BBX31 act as key negative regulators of light signaling, and their transcription is repressed by ELONGATED HYPOCOTYL5 through directly associating with their promoters.

In humans, low serum HSP27 levels are associated with the presence of coronary artery disease and prognostic of future adverse clinical events. In mouse models of atherosclerosis, increasing HSP27 levels reduced lesion progression and promoted features of plaque stability. Serum HSP27 levels may represent a potential therapeutic target for atherosclerosis.

The recent epidemic of obesity has been associated with a sharp rise in the incidence of non-alcoholic fatty liver disease (NAFLD). However, the underlying mechanism(s) remains poorly described and effective therapeutic approaches against NAFLD are lacking. The results establish that microRNA-378 facilitates the development of hepatic inflammation and fibrosis and suggests the therapeutic potential of microRNA-378 inhibitor for the treatment of NAFLD.

Objective-We recently identified HSP27 as an atheroprotective protein that acts extracellularly to prevent foam cell formation and atherogenesis in female but not male mice, where serum levels of HSP27 were increased and inversely correlated with degree of lesion burden. In the current study we sought to determine whether estrogens are required for the observed atheroprotective benefits of HSP27 as well as its extracellular release. Methods and Results-In vitro estrogens prompted the release of HSP27 from macrophages in an ER␤ specific manner that involved exosomal trafficking. Ovariectomy nullified the previously recognized attenuation in aortic lesion area in HSP27 o/e apoE Ϫ/Ϫ mice compared to apoE Ϫ/Ϫ mice. Supplementation with 17␤-estradiol resulted in a Ͼ15ϫ increase in uterine weight and attenuation of atherogenesis in all mice, although HSP27o/e apoE Ϫ/Ϫ had 34% less lesion burden compared to apoE Ϫ/Ϫ mice. Mice treated with the ER␤-specific agonist, DPN had no effect on uterine weight but a 28% decrease in aortic lesion area in HSP27o/e apoE Ϫ/Ϫ compared to apoE Ϫ/Ϫ mice. HSP27 serum levels showed a similar gradual increase with E2 and DPN replacement treatment but did not change in untreated mice. Key Words: heat shock Ⅲ proteins Ⅲ estrogen Ⅲ receptors Ⅲ athersclerosis P reviously, we showed in human coronary arteries that Heat Shock Protein 27 (HSP27) expression is lower in atherosclerotic plaques compared to lesion-free arterial segments, suggesting higher levels of this protein may confer protection from disease. 1 More recently, we demonstrated that HSP27 is an atheroprotective protein that acts in the extracellular space to reduce foam cell formation and atherogenesis by binding scavenger receptor-A on the surface of macrophages and preventing the uptake of acLDL as well as inflammatory cytokine release. Moreover, when fed a highfat diet for 4 weeks apoE null (apoE Ϫ/Ϫ ) mice that overexpress HSP27 (HSP27 o/e apoE Ϫ/Ϫ ) show a reduction in aortic atherosclerotic plaque area-however, only in female and not male mice. 2 Interestingly, female HSP27 overexpressing mice have significantly higher levels of serum HSP27 than do their male counterparts, and serum HSP27 levels show a strong inverse correlation with atherosclerotic lesion area. These sex-specific effects of HSP27 hint that the function or release of this intriguing protein may in some way be hormonally modulated. Conclusions-TheGiven our previous observations that estrogens cause HSP27 secretion, and that HSP27 physically associates with ER␤ but not ER␣, 3 we sought to determine the role for these receptors in the release of HSP27 both in vitro and in vivo. As described herein, we now report that the release of HSP27 from macrophages is preferentially induced via specific ER␤ stimulation (not ER␣) and induction of HSP27 release in vivo via the ER␤-specific modulator DPN increases serum HSP27 levels to a level comparable to 17␤-estradiol (E2)-yet unlike E2 attenuates atherogenesis without causing unwanted uterine hypertrophy. Materials and Me...

Light and the circadian clock are two essential external and internal cues affecting seedling development. COLD-REGULATED GENE27 (COR27), which is regulated by cold temperatures and light signals, functions as a key regulator of the circadian clock. Here, we report that COR27 acts as a negative regulator of light signaling. COR27 physically interacts with the CONSTITUTIVELY PHOTOMORPHOGENIC1 (COP1)-SUPPRESSOR OF PHYTOCHROME A1 (SPA1) E3 ubiquitin ligase complex and undergoes COP1-mediated degradation via the 26S proteasome system in the dark. cor27 mutant seedlings exhibit shorter hypocotyls, while transgenic lines overexpressing COR27 show elongated hypocotyls in the light. In addition, light induces the accumulation of COR27. On one hand, accumulated COR27 interacts with ELONGATED HYPOCOTYL5 (HY5) to repress HY5 DNA binding activity. On the other hand, COR27 associates with the chromatin at the PHYTOCHROME INTERACTING FACTOR4 (PIF4) promoter region and upregulates PIF4 expression in a circadian clock-dependent manner. Together, our findings reveal a mechanistic framework whereby COR27 represses photomorphogenesis in the light and provide insights toward how light and the circadian clock synergistically control hypocotyl growth.

AimsExpression of Heat Shock Protein-27 (HSP27) is reduced in human coronary atherosclerosis. Over-expression of HSP27 is protective against the early formation of lesions in atherosclerosis-prone apoE−/− mice (apoE−/−HSP27o/e) - however, only in females. We now seek to determine if chronic HSP27 over-expression is protective in a model of advanced atherosclerosis in both male and female apoE−/− mice.Methods and ResultsAfter 12 weeks on a high fat diet, serum HSP27 levels rose more than 16-fold in male and female apoE−/−HSP27o/e mice, although females had higher levels than males. Relative to apoE−/− mice, female apoE−/−HSP27o/e mice showed reductions in aortic lesion area of 35% for en face and 30% for cross-sectional sinus tissue sections – with the same parameters reduced by 21% and 24% in male cohorts; respectively. Aortic plaques from apoE−/−HSP27o/e mice showed almost 50% reductions in the area occupied by cholesterol clefts and free cholesterol, with fewer macrophages and reduced apoptosis but greater intimal smooth muscle cell and collagen content. The analysis of the aortic mechanical properties showed increased vessel stiffness in apoE−/−HSP27o/e mice (41% in female, 34% in male) compare to apoE−/− counterparts.ConclusionsChronic over-expression of HSP27 is atheroprotective in both sexes and coincides with reductions in lesion cholesterol accumulation as well as favorable plaque remodeling. These data provide new clues as to how HSP27 may improve not only the composition of atherosclerotic lesions but potentially their stability and resilience to plaque rupture.

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