Highlights d An active b2AR structure was obtained by fusion with residues 381-394 of Gs (GsCT) d GsCT interacts with the b2AR differently compared with the b2AR-Gs complex structure d The structure of Gs GDP reveals the conformation of GsCT before b2AR engagement d A model for the initial stages of b2AR-Gs complex formation is proposed

The familial cylindromatosis tumor suppressor CYLD is known to contain three cytoskeleton-associated protein glycine-rich (CAP-Gly) domains, which exist in a number of microtubule-binding proteins and are responsible for their association with microtubules. However, it remains elusive whether CYLD interacts with microtubules and, if so, whether the interaction is mediated by the CAP-Gly domains. In this study, our data demonstrate that CYLD associates with microtubules both in cells and in vitro, and the first CAP-Gly domain of CYLD is mainly responsible for the interaction. Knockdown of cellular CYLD expression dramatically delays microtubule regrowth after nocodazole washout, indicating an activity for CYLD in promoting microtubule assembly. Our data further demonstrate that CYLD enhances tubulin polymerization into microtubules by lowering the critical concentration for microtubule assembly. In addition, we have identified by wound healing assay a critical role for CYLD in mediating cell migration and found that its first CAP-Gly domain is required for this activity. Thus CYLD joins a growing list of CAP-Gly domain-containing proteins that regulate microtubule dynamics and function.

Delta-secretase cleaves both APP and Tau to mediate the formation of amyloid plaques and neurofibrillary tangle in Alzheimer’s disease (AD). However, how aging contributes to an increase in delta-secretase expression and AD pathologies remains unclear. Here we show that a CCAAT-enhancer-binding protein (C/EBPβ), an inflammation-regulated transcription factor, acts as a key age-dependent effector elevating both delta-secretase (AEP) and inflammatory cytokines expression in mediating pathogenesis in AD mouse models. We find that C/EBPβ regulates delta-secretase transcription and protein levels in an age-dependent manner. Overexpression of C/EBPβ in young 3xTg mice increases delta-secretase and accelerates the pathological features including cognitive dysfunctions, which is abolished by inactive AEP C189S. Conversely, depletion of C/EBPβ from old 3xTg or 5XFAD mice diminishes delta-secretase and reduces AD pathologies, leading to amelioration of cognitive impairment in these AD mouse models. Thus, our findings support that C/EBPβ plays a pivotal role in AD pathogenesis via increasing delta-secretase expression.

Previous studies have shown that metformin not only is a hypoglycemic agent but also has neuroprotective effects. However, the mechanism of action of metformin in ischemic stroke is unclear. Oxidative stress is an important factor in the pathogenesis of cerebral ischemia-reperfusion injury. It has been reported that metformin is associated with stroke risk in the clinical population. This study is aimed at investigating the effect and mechanism of metformin in an experimental model of oxidative stress induced by ischemia/reperfusion (I/R) in vivo and oxygen glucose deprivation/reperfusion (OGD/R) in vitro. Metformin (100, 200, and 300 mg/kg) was administered intraperitoneally immediately after induction of cerebral ischemia. The indicators of oxidative stress selected were antioxidant enzyme activities of catalase, malondialdehyde (MDA), nitric oxide (NO), superoxide dismutase (SOD), and glutathione peroxidation enzyme (GSHPx). First, we demonstrated that metformin can significantly alleviate acute and chronic cerebral I/R injury and it has a strong regulatory effect on stroke-induced oxidative stress. It can reduce the elevated activities of MDA and NO and increase the levels of GSHPx and SOD in the cerebrum of mice and N2a cells exposed to I/R. Furthermore, real-time PCR and western blot were used to detect the expression of long noncoding RNA H19 (lncRNA-H19), microRNA-148a-3p (miR-148a-3p), and Rho-associated protein kinase 2 (Rock2). The direct interaction of lncRNA-H19, miR-148a-3p, and Rock2 was tested using a dual luciferase reporter assay. lncRNA-H19 altered OGD/R-induced oxidative stress by modulating miR-148a-3p to increase Rock2 expression. The expression of lncRNA-H19 and Rock2 could be downregulated with metformin in vivo and in vitro. In conclusion, our study confirmed that metformin exerts neuroprotective effects by regulating ischemic stroke-induced oxidative stress injury via the lncRNA-H19/miR-148a-3p/Rock2 axis. These results provide new evidence that metformin may represent a potential treatment for stroke-related brain injury.