Xingliang Zhou

Activation of Wnt/β-catenin signaling can induce both self-renewal and differentiation in naive pluripotent embryonic stem cells (ESCs). To gain insights into the mechanism by which Wnt/β-catenin regulates ESC fate, we screened and characterized its downstream targets. Here, we show that the self-renewal-promoting effect of Wnt/β-catenin signaling is mainly mediated by two of its downstream targets, Klf2 and Tfcp2l1. Forced expression of Klf2 and Tfcp2l1 can not only induce reprogramming of primed state pluripotency into naive state ESCs, but also is sufficient to maintain the naive pluripotent state of ESCs. Conversely, downregulation of Klf2 and Tfcp2l1 impairs ESC self-renewal mediated by Wnt/β-catenin signaling. Our study therefore establishes the pivotal role of Klf2 and Tfcp2l1 in mediating ESC self-renewal promoted by Wnt/β-catenin signaling.

Heat shock transcription factor 1 (HSF1) has been implicated in the differential regulation of cell stress and disease states. β‐catenin activation is essential for immune homeostasis. However, little is known about the role of macrophage HSF1‐β‐catenin signaling in the regulation of NLRP3 inflammasome activation during ischemia/reperfusion (I/R) injury (IRI) in the liver. This study investigated the functions and molecular mechanisms by which HSF1‐β‐catenin signaling influenced NLRP3‐mediated innate immune response in vivo and in vitro . Using a mouse model of IR‐induced liver inflammatory injury, we found that mice with a myeloid‐specific HSF1 knockout (HSF1 M‐KO ) displayed exacerbated liver damage based on their increased serum alanine aminotransferase levels, intrahepatic macrophage/neutrophil trafficking, and proinflammatory interleukin (IL)‐1β levels compared to the HSF1‐proficient (HSF1 FL/FL ) controls. Disruption of myeloid HSF1 markedly increased transcription factor X‐box‐binding protein (XBP1), NLR family, pyrin domain‐containing 3 (NLRP3), and cleaved caspase‐1 expression, which was accompanied by reduced β‐catenin activity. Knockdown of XBP1 in HSF1‐deficient livers using a XBP1 small interfering RNA ameliorated hepatocellular functions and reduced NLRP3/cleaved caspase‐1 and IL‐1β protein levels. In parallel in vitro studies, HSF1 overexpression increased β‐catenin (Ser552) phosphorylation and decreased reactive oxygen species (ROS) production in bone‐marrow‐derived macrophages. However, myeloid HSF1 ablation inhibited β‐catenin, but promoted XBP1. Furthermore, myeloid β‐catenin deletion increased XBP1 messenger RNA splicing, whereas a CRISPR/CRISPR‐associated protein 9‐mediated XBP1 knockout diminished NLRP3/caspase‐1. Conclusion: The myeloid HSF1‐β‐catenin axis controlled NLRP3 activation by modulating the XBP1 signaling pathway. HSF1 activation promoted β‐catenin, which, in turn, inhibited XBP1, leading to NLRP3 inactivation and reduced I/R‐induced liver injury. These findings demonstrated that HSF1/β‐catenin signaling is a novel regulator of innate immunity in liver inflammatory injury and implied the therapeutic potential for management of sterile liver inflammation in transplant recipients. (H epatology 2016;64:1683‐1698).

Background: It is widely accepted that cognitive processes, such as learning and memory, are affected in depression, but the molecular mechanisms underlying the interactions of these 2 disorders are not clearly understood. Recently, glycogen synthase kinase-3 beta (GSK-3β)/β-catenin signaling was shown to play an important role in the regulation of learning and memory. Methods: The present study used a rat model of depression, chronic unpredictable stress, to determine whether hippocampal GSK-3β/β-catenin signaling was involved in learning and memory alterations. Results: Our results demonstrated that chronic unpredictable stress had a dramatic influence on spatial cognitive performance in the Morris water maze task and reduced the phosphorylation of Ser9 of GSK-3β as well as the total and nuclear levels of β-catenin in the hippocampus. Inhibition of GSK3β by SB216763 significantly ameliorated the cognitive deficits induced by chronic unpredictable stress, while overexpression of GSK3β by AAV-mediated gene transfer significantly decreased cognitive performance in adult rats. In addition, chronic unpredictable stress exposure increased the expression of the canonical Wnt antagonist Dkk-1. Furthermore, chronic administration of corticosterone significantly increased Dkk-1 expression, decreased the phosphorylation of Ser9 of GSK-3β, and resulted in the impairment of hippocampal learning and memory. Conclusions: Our results indicate that impairment of learning and memory in response to chronic unpredictable stress may be attributed to the dysfunction of GSK-3β/β-catenin signaling mediated by increased glucocorticoid signaling via Dkk-1.