查看更多>>摘要：Autophagy is a multi-step process regulated in part by AMP-activated protein kinase (AMPK). Phosphorylation of threonine 172 on the AMPK alpha-subunit enhances AMPK kinase activity, resulting in activation of downstream signaling. Integrin-mediated cell adhesion activates Src/ Focal Adhesion Kinase (FAK) signaling complex, which regulates multiple cellular processes including cell survival. We show here that Src signaling leads to direct phosphorylation of the AMPK-alpha subunit on a novel site, tyrosine 179, resulting in suppression of AMPK-T172 phosphorylation and autophagy upon integrin-mediated cell adhesion. By using chemical inhibitors, genetic cell models and targeted mutagenesis, we confirm an important role for Src and FAK in suppressing AMPK signaling and autophagy induced by various additional stimuli, including glucose starvation. Furthermore, we found that autophagy suppression by hydroxychloroquine promotes apoptosis in a cancer cell model that had been treated with Src inhibitors. Our findings reveal a link between the Src/ FAK complex and AMPK/ autophagy regulation, which may play an important role in the maintenance of normal cellular homeostasis and tumor progression.
查看更多>>摘要：Our previous study has revealed that GFP-alpha-synuclein overexpressing SH-SY5Y cells-derived exosomes (GFP-SNCA Exo) decrease autophagy in microglia via their load of miRNAs. However, it is unclear whether GFP-SNCA Exo can affect microglial inflammation via modulation of autophagy. In order to investigate the effects of miRNAs carried by GFP-SNCA Exo on autophagy and inflammation of microglia. SH-SY5Y cells were transfected with lentivirus expressing alpha-synuclein and then their exosomes were collected. Western blot and laser confocal images showed that alpha-synuclein transferred between SH-SY5Y cells and microglia through exosomes. Differentially expressed miRNAs between GFP-SNCA Exo and the vector exosomes were detected by microarray analysis. After bioinformatics analysis of the differentially expressed miRNAs, we found that their target genes were enriched in the MAPK and autophagy-associated signaling pathway. The expression of P62, p-JNK/JNK, and p-ERK/ERK and the release of IL-6 significantly increased whereas LC3 II/I decreased in microglia exposed to GFP-SNCA Exo for 48 h when compared to the control group. But rapamycin could reverse the increasing expression of p-JNK/JNK, p-ERK/ERK and the release of IL-6 induced by GFP-SNCA Exo. Dual immunofluorescence staining for LC3B and LAMP1 showed that the fluorescence density of LC3B decreased and the fluorescence of LC3B and LAMP1 were not co-located in microglia after 48 h co-culture with GFP-SNCA Exo compared with the control group, which indicated that these exosomes decreased autophagy and impaired the autophagy flux in recipient microglia. Taken together, our results indicate that GFP-SNCA Exo activate the MAPK signaling pathway and inflammation by decreasing autophagy in microglia.
Agarwal, Shailesh R.Sherpa, Rinzhin T.Moshal, Karni S.Harvey, Robert D....
10页
查看更多>>摘要：Activation of different receptors that act by generating the common second messenger cyclic adenosine monophosphate (cAMP) can elicit distinct functional responses in cardiac myocytes. Selectively sequestering cAMP activity to discrete intracellular microdomains is considered essential for generating receptor-specific responses. The processes that control this aspect of compartmentalized cAMP signaling, however, are not completely clear. Over the years, technological innovations have provided critical breakthroughs in advancing our understanding of the mechanisms underlying cAMP compartmentation. Some of the factors identified include localized production of cAMP by differential distribution of receptors, localized breakdown of this second messenger by targeted distribution of phosphodiesterase enzymes, and limited diffusion of cAMP by protein kinase A (PKA)dependent buffering or physically restricted barriers. The aim of this review is to provide a discussion of our current knowledge and highlight some of the gaps that still exist in the field of cAMP compartmentation in cardiac myocytes.
查看更多>>摘要：Macrophages, which are the main regulators of the tumor-associated microenvironment, play a crucial role in the progression of various tumors. The anti-inflammatory role of beta-catenin in macrophages has been extensively studied in recent years. However, the association between macrophages and beta-catenin with regards to the development of glioma has not yet been investigated, at least to the best of our knowledge. The present study found that fibroblast growth factor 20 (FGF20), as a paracrine cytokine, was secreted by glioma cells and acted on macrophages. FGF20 treated macrophages exhibited a decreased pro-inflammatory phenotype upon LPS and IFN-gamma stimulation, characterized by the decreased the level of M1 macrophage markers and the reduced production of pro-inflammatory cytokines. Mechanistic analysis revealed that FGF20 interacted with FGF receptor 1 isoform of macrophages, and subsequently increased the stability of beta-catenin via phosphorylating GSK3 beta, which suppressed macrophage polarization to the M1-phenotype. Finally, it was found that FGF20 of glioma cells expression was upregulated by the glucocorticoids (GCs) treatment, and decreased FGF20 expression of glioma cells markedly blocked the effects of GCs on the polarization of macrophages. On the whole, the present study demonstrates that FGF20, secreted from glioma cells, participates the GCs regulated macrophage function and exerts anti-inflammatory effects during the treatment of glioma by GCs. Moreover, a molecular link was identified between glioma cells and macrophages, demonstrating that FGF20 modulates the GCs-induced dysfunction of macrophages during glioma development.
查看更多>>摘要：Ionizing radiation (IR) is a constant feature of our environment and one that can dramatically affect organismal health and development. Although the impacts of high-doses of IR on mammalian cells and systems have been broadly explored, there are still challenges in accurately quantifying biological responses to IR, especially in the low-dose range to which most individuals are exposed in their lifetime. The resulting uncertainty has led to the entrenchment of conservative radioprotection policies around the world. Thus, uncovering long-sought molecular mechanisms and tissue responses that are targeted by IR could lead to more informed policymaking and propose new therapeutic avenues for a variety of pathologies. One often overlooked target of IR is mRNA translation, a highly regulated cellular process that consumes more than 40% of the cell's energy. In response to environmental stimuli, regulation of mRNA translation allows for precise and rapid changes to the cellular proteome, and unsurprisingly high-dose of IR was shown to trigger a severe reprogramming of global protein synthesis allowing the cell to conserve energy by preventing the synthesis of unneeded proteins. Nonetheless, under these conditions, certain mRNAs encoding specific proteins are translationally favoured to produce the factors essential to repair the cell or send it down the path of no return through programmed cell death. Understanding the mechanisms controlling protein synthesis in response to varying doses of IR could provide novel insights into how this stress-mediated cellular adaptation is regulated and potentially uncover novel targets for radiosensitization or radioprotection. Here, we review the current literature on the effects of IR at both high- and low-dose on the mRNA translation machinery.
查看更多>>摘要：Ror2 plays an important role in neuronal development, neuronal plasticity, and neuropathic pain. In our previous pilot study, we found that Ror2 and GFAP (a marker of astrocytes) protein levels increased in thoracic dorsal root ganglia from postoperative day (POD) 7 to POD 21 in rats with chronic post-thoracotomy pain (CPTP). In the present study, we aimed to further explore the roles of Ror2 and activated astrocytes during CPTP development. Ror2, c-JUN, and C3aR levels increased and the activated astrocytes were mainly expressed as the A1 phenotype in the spinal cord dorsal horn of the rats with CPTP. The knockdown of Ror2 in the spinal cord astrocytes alleviated thoracotomy-induced mechanical hyperalgesia and cold allodynia as well as reverted the A1/A2 ratio of the reactive astrocytes, downregulating the expression of c-JUN and C3aR in rats with CPTP. These results suggest that Ror2 in the spinal cord astrocytes mediates the transformation of A1/A2 reactive astrocytes via regulating the expressions of the c-JUN and C3aR in CPTP. Furthermore, the suppression of Ror2 could be utilized as a new strategy to help prevent CPTP.
查看更多>>摘要：Nonsense-mediated mRNA decay (NMD), a cellular RNA quality system, has been shown to be an ancestral form of cellular antiviral response that can restrict viral infection by targeting viral RNA for degradation or other various mechanisms. In support to this hypothesis, emerging evidences unraveled that viruses have evolved numerous mechanisms to circumvent or modulate the NMD pathway to ensure unhindered replication within the host cell. In this study, we investigated the potential interplay between the cellular NMD pathway and rotavirus (RV). Our data suggested that rotavirus infection resulted in global inhibition of NMD pathway by downregulating the expression of UPF1 in a strain independent manner. UPF1 expression was found to be regulated at the post-transcriptional level by ubiquitin-proteasome mediated degradation pathway. Subsequent studies revealed rotaviral non-structural protein 5 (NSP5) associates with UPF1 and promotes its cullin-dependent proteasome mediated degradation. Furthermore, ectopic expression of UPF1 during RV infection resulted in reduced expression of viral proteins and viral RNAs leading to diminished production of infective rotavirus particles, suggesting the anti-rotaviral role of UPF1. Finally, the delayed degradation kinetics of transfected rotaviral RNA in UPF1 and UPF2 depleted cells and the association of UPF1 and UPF2 with viral RNAs suggested that NMD targets rotaviral RNAs for degradation. Collectively, the present study demonstrates the antiviral role of NMD pathway during rotavirus infection and also reveals the underlying mechanism by which rotavirus overwhelms NMD pathway to establish successful replication.
NSTL
Elsevier