Developing supramolecular porous crystalline frameworks with tailor-made architectures from advanced secondary building units (SBUs) remains a pivotal challenge in reticular chemistry. Particularly ...for hydrogen-bonded organic frameworks (HOFs), construction of geometrical cavities through secondary units has been rarely achieved. Herein, a body-centered cubic HOF (TCA_NH
) with octahedral cages was constructed by a C
-symmetric building block and NH
node-assembled cluster (NH
)
(COOH)
(H
O)
that served as supramolecular secondary building units (SSBUs), akin to the polynuclear SBUs in reticular chemistry. Specifically, the octahedral cages could encapsulate four homogenous haloforms including CHCl
, CHBr
, and CHI
with truncated octahedron configuration. Crystallographic evidence revealed the cages served as spatially-confined nanoreactors, enabling fast, broadband photochromic effect associated with the reversible photo/thermal transformation between encapsulated CHI
and I
. Overall, this work provides a strategy by shaping SSBUs to expand the framework topology of HOFs and a prototype of hydrogen-bonded nanoreactors to accommodate reversible photochromic reactions.
Immune recognition of pathogen-associated molecular patterns (PAMPs) by pattern recognition receptors often activates proinflammatory NF-κB signalling
. Recent studies indicate that the bacterial ...metabolite D-glycero-β-D-manno-heptose 1,7-bisphosphate (HBP) can activate NF-κB signalling in host cytosol
, but it is unclear whether HBP is a genuine PAMP and the cognate pattern recognition receptor has not been identified. Here we combined a transposon screen in Yersinia pseudotuberculosis with biochemical analyses and identified ADP-β-D-manno-heptose (ADP-Hep), which mediates type III secretion system-dependent NF-κB activation and cytokine expression. ADP-Hep, but not other heptose metabolites, could enter host cytosol to activate NF-κB. A CRISPR-Cas9 screen showed that activation of NF-κB by ADP-Hep involves an ALPK1 (alpha-kinase 1)-TIFA (TRAF-interacting protein with forkhead-associated domain) axis. ADP-Hep directly binds the N-terminal domain of ALPK1, stimulating its kinase domain to phosphorylate and activate TIFA. The crystal structure of the N-terminal domain of ALPK1 and ADP-Hep in complex revealed the atomic mechanism of this ligand-receptor recognition process. HBP was transformed by host adenylyltransferases into ADP-heptose 7-P, which could activate ALPK1 to a lesser extent than ADP-Hep. ADP-Hep (but not HBP) alone or during bacterial infection induced Alpk1-dependent inflammation in mice. Our findings identify ALPK1 and ADP-Hep as a pattern recognition receptor and an effective immunomodulator, respectively.
Autophagy is a degradative process that recycles long-lived and faulty cellular components. It is linked to many diseases and is required for normal development. ULK1, a mammalian serine/threonine ...protein kinase, plays a key role in the initial stages of autophagy, though the exact molecular mechanism is unknown. Here we report identification of a novel protein complex containing ULK1 and two additional protein factors, FIP200 and ATG13, all of which are essential for starvation-induced autophagy. Both FIP200 and ATG13 are critical for correct localization of ULK1 to the pre-autophagosome and stability of ULK1 protein. Additionally, we demonstrate by using both cellular experiments and a de novo in vitro reconstituted reaction that FIP200 and ATG13 can enhance ULK1 kinase activity individually but both are required for maximal stimulation. Further, we show that ATG13 and ULK1 are phosphorylated by the mTOR pathway in a nutrient starvation-regulated manner, indicating that the ULK1·ATG13·FIP200 complex acts as a node for integrating incoming autophagy signals into autophagosome biogenesis.
Autophagy mediates the cellular response to nutrient deprivation, protein aggregation, and pathogen invasion in human. Dysfunction of autophagy has been implicated in multiple human diseases ...including cancer. The identification of novel autophagy factors in mammalian cells will provide critical mechanistic insights into how this complicated cellular pathway responds to a broad range of challenges. Here, we report the cloning of an autophagy-specific protein that we called Barkor (Beclin 1-associated autophagy-related key regulator) through direct interaction with Beclin 1 in the human phosphatidylinositol 3-kinase class III complex. Barkor shares 18% sequence identity and 32% sequence similarity with yeast Atg14. Elimination of Barkor expression by RNA interference compromises starvation- and rapamycin-induced LC3 lipidation and autophagosome formation. Overexpression of Barkor leads to autophagy activation and increased number and enlarged volume of autophagosomes. Tellingly, Barkor is also required for suppression of the autophagy-mediated intracellular survival of Salmonella typhimurium in mammalian cells. Mechanistically, Barkor competes with UV radiation resistance associated gene product (UVRAG) for interaction with Beclin 1, and the complex formation of Barkor and Beclin1 is required for their localizations to autophagosomes. Therefore, we define a regulatory signaling pathway mediated by Barkor that positively controls autophagy through Beclin 1 and represents a potential target for drug development in the treatment of human diseases implicated in autophagic dysfunction.
Autophagy is a major catabolic pathway in eukaryotes associated with a broad spectrum of human diseases. In autophagy, autophagosomes carrying cellular cargoes fuse with lysosomes for degradation. ...However, the molecular mechanism underlying autophagosome maturation is largely unknown. Here we report that TECPR1 binds to the Atg12-Atg5 conjugate and phosphatidylinositol 3-phosphate (PtdIns3P) to promote autophagosome-lysosome fusion. TECPR1 and Atg16 form mutually exclusive complexes with the Atg12-Atg5 conjugate, and TECPR1 binds PtdIns(3)P upon association with the Atg12-Atg5 conjugate. Strikingly, TECPR1 localizes to and recruits Atg5 to autolysosome membrane. Consequently, elimination of TECPR1 leads to accumulation of autophagosomes and blocks autophagic degradation of LC3-II and p62. Finally, autophagosome maturation marked by GFP-mRFP-LC3 is defective in TECPR1-deficient cells. Thus, we propose that the concerted interactions among TECPR1, Atg12-Atg5, and PtdIns(3)P provide the fusion specificity between autophagosomes and lysosomes and that the assembly of this complex initiates the autophagosome maturation process.
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► TECPR1 and Atg16 form two mutually exclusive complexes with Atg12-Atg5 ► TECPR1 localizes to and recruits Atg5 to autolysosomes ► Atg12-Atg5-TECPR1 complex binds to PtdIns(3)P specifically ► TECPR1 is required for autophagosome maturation
The concept of spirituality has a long philosophical history. Based on detailed studies of a history of spiritual exercises from Socrates, the Stoics, Epicureanism, to early Christianity, the former ...catholic priest Pierre Hadot conceives philosophical practice as spiritual exercises in learning how to live a philosophical life. Following this idea, a number of philosophers such as Gerd B. Achenbach started the contemporary movement of philosophical practice in the 1980s, which aimed to apply philosophical theories and methods to discussions about issues people constantly encounter in life, mainly in the forms of philosophical counseling and philosophical therapy. In this paper, after showing that philosophical practice has already become a new frontier in philosophical research, we further argue that philosophical practice as spiritual exercises is an exercise of reason and logos, while certain kinds of religious exercises such as Zen arts can also constitute an important part of philosophical practice. We conclude that in light of the distinct plurality of the methods and modes of philosophical practice and the spiritual exercises involved, philosophical practice can be considered a meaningful and applicable approach to pursuing truth, wisdom, and virtue, which is of great didactic and ethical significance in the post-COVID-19 era.
TET family enzymes successively oxidize 5-methylcytosine to 5-hydroxymethylcytosine, 5-formylcytosine, and 5-carboxylcytosine, leading to eventual demethylation. 5hmC and TET enzymes occupy distinct ...chromatin regions, suggesting unknown mechanisms controlling the fate of 5hmC within diverse chromatin environments. Here, we report that SALL4A preferentially associates with 5hmC in vitro and occupies enhancers in mouse embryonic stem cells in a largely TET1-dependent manner. Although most 5hmC at SALL4A peaks undergoes further oxidation, this process is abrogated upon deletion of Sall4 gene, with a concomitant reduction of TET2 at these regions. Thus, SALL4A facilitates further oxidation of 5hmC at its binding sites, which requires its 5hmC-binding activity and TET2, supporting a collaborative action between SALL4A and TET proteins in regulating stepwise oxidation of 5mC at enhancers. Our study identifies SALL4A as a 5hmC binder, which facilitates 5hmC oxidation by stabilizing TET2 association, thereby fine-tuning expression profiles of developmental genes in mouse embryonic stem cells.
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•A SILAC-assisted DNA pull down reveals SALL4A preferentially binds 5hmC in vitro•SALL4A occupies enhancers in mouse ESCs, largely in a TET1-dependent manner•SALL4A facilitates 5hmC further oxidation at its binding sites•TET2 is the main enzyme catalyzing 5hmC further oxidation at SALL4A-binding sites
Xiong et al. identify SALL4A as a protein preferentially associating with 5hmC in vitro. In mouse ESCs, TET1 is the primary contributor to 5hmC production and recruiter of SALL4A at enhancers, whereas SALL4A stabilizes TET2 association and facilitates further oxidation of 5hmC to fine-tune expression of developmental genes.
Cell-surface-localized plant immune receptors, such as FLS2, detect pathogen-associated molecular patterns (PAMPs) and initiate PAMP-triggered immunity (PTI) through poorly understood ...signal-transduction pathways. The pathogenic Pseudomonas syringae effector AvrPphB, a cysteine protease, cleaves the Arabidopsis receptor-like cytoplasmic kinase PBS1 to trigger cytoplasmic immune receptor RPS5-specified effector-triggered immunity (ETI). Analyzing the function of AvrPphB in plants lacking RPS5, we find that AvrPphB can inhibit PTI by cleaving additional PBS1-like (PBL) kinases, including BIK1, PBL1, and PBL2. In unstimulated plants, BIK1 and PBL1 interact with FLS2 and are rapidly phosphorylated upon FLS2 activation by its ligand flg22. Genetic and molecular analyses indicate that BIK1, and possibly PBL1, PBL2, and PBS1, integrate immune signaling from multiple immune receptors. Whereas AvrPphB-mediated degradation of one of these kinases, PBS1, is monitored by RPS5 to initiate ETI, this pathogenic effector targets other PBL kinases for PTI inhibition.
► Pseudomonas syringae effector AvrPphB inhibits PAMP-triggered immunity (PTI) ► PBS1-like kinases required for PTI are AvrPphB protease substrates ► The PBS1-like kinase BIK1 interacts with the PTI receptor FLS2 ► PBS1-like kinases integrate signaling from multiple immune receptors
Power quality events are usually associated with more than one disturbance and their recognition is typically based on multilabel learning. In this study, we propose a new method for recognizing ...multiple power quality disturbances (MPQDs) based on variational mode decomposition (VMD) and a random discriminative projection extreme learning machine for multilabel learning (RDPEML). First, VMD is employed to decompose the MPQDs into several intrinsic mode functions and the standard energy differences of each mode are extracted as features that form the input vectors of the classifier. Second, a novel multilabel classifier called RDPEML is constructed by combining a random discriminative projection multiclass extreme learning machine (ELM) and a thresholding learning method-based kernel ELM. In order to obtain better classification performance, a tenfold cross-validation embedded particle swarm optimization approach is utilized to search for the optimal values of the structural parameters. Finally, a test study was conducted using MATLAB synthetic signals and real signals sampled from a three-phase standard source under different noise conditions. Compared with the several recent state-of-the-art multilabel learning algorithms, RDPEML achieved better classification performance with superior computational speed.
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