Ischemic preconditioning (IPC) affords tissue protection in organs including kidneys; however, the underlying mechanism remains unclear. Here we demonstrate an important role of ...macroautophagy/autophagy (especially mitophagy) in the protective effect of IPC in kidneys. IPC induced autophagy in renal tubular cells in mice and suppressed subsequent renal ischemia-reperfusion injury (IRI). The protective effect of IPC was abolished by pharmacological inhibitors of autophagy and by the ablation of Atg7 from kidney proximal tubules. Pretreatment with BECN1/Beclin1 peptide induced autophagy and protected against IRI. These results suggest the dependence of IPC protection on renal autophagy. During IPC, the mitophagy regulator PINK1 (PTEN induced putative kinase 1) was activated. Both IPC and BECN1 peptide enhanced mitolysosome formation during renal IRI in mitophagy reporter mice, suggesting that IPC may protect kidneys by activating mitophagy. We further established an in vitro model of IPC by inducing 'chemical ischemia' in kidney proximal tubular cells with carbonyl cyanide 3-chlorophenylhydrazone (CCCP). Brief treatment with CCCP protected against subsequent injury in these cells and the protective effect was abrogated by autophagy inhibition. In vitro IPC increased mitophagosome formation, enhanced the delivery of mitophagosomes to lysosomes, and promoted the clearance of damaged mitochondria during subsequent CCCP treatment. IPC also suppressed mitochondrial depolarization, improved ATP production, and inhibited the generation of reactive oxygen species. Knockdown of Pink1 suppressed mitophagy and reduced the cytoprotective effect of IPC. Together, these results suggest that autophagy, especially mitophagy, plays an important role in the protective effect of IPC.
Abbreviations: ACTB: actin, beta; ATG: autophagy related; BNIP3: BCL2 interacting protein 3; BNIP3L/NIX: BCL2 interacting protein 3 like; BUN: blood urea nitrogen; CASP3: caspase 3; CCCP: carbonyl cyanide 3-chlorophenylhydrazone; COX4I1: cytochrome c oxidase subunit 4I1; COX8: cytochrome c oxidase subunit 8; DAPI: 4ʹ,6-diamidino-2-phenylindole; DNM1L: dynamin 1 like; EGFP: enhanced green fluorescent protein; EM: electron microscopy; ER: endoplasmic reticulum; FC: floxed control; FIS1: fission, mitochondrial 1; FUNDC1: FUN14 domain containing 1; H-E: hematoxylin-eosin; HIF1A: hypoxia inducible factor 1 subunit alpha; HSPD1: heat shock protein family D (Hsp60) member 1; IMMT/MIC60: inner membrane mitochondrial protein; IPC: ischemic preconditioning; I-R: ischemia-reperfusion; IRI: ischemia-reperfusion injury; JC-1: 5,5ʹ,6,6ʹ-tetrachloro-1,1ʹ,3,3ʹ-tetraethylbenzimidazolylcarbocyanine iodide; KO: knockout; MAP1LC3B/LC3B: microtubule associated protein 1 light chain 3 beta; mito-QC: mito-quality control; mRFP: monomeric red fluorescent protein; NAC: N-acetylcysteine; PINK1: PTEN induced putative kinase 1; PPIB: peptidylprolyl isomerase B; PRKN: parkin RBR E3 ubiquitin protein ligase; ROS: reactive oxygen species; RPTC: rat proximal tubular cells; SD: standard deviation; sIPC: simulated IPC; SQSTM1/p62: sequestosome 1; TOMM20: translocase of outer mitochondrial membrane 20; TUNEL: terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling
The Hippo signaling pathway was originally discovered in Drosophila and shown to be critical for organ size control and tumorigenesis. This pathway consists of a cascade of kinases and several ...adaptors that lead to the phosphorylation and inhibition, through nuclear exclusion, of the transcriptional cofactor Yorkie in Drosophila or YAP （yes associated protein） in mammals. Recent studies demonstrate that cardiac-specific deletion of the Hippo pathway kinase Mst （STE20-1ike protein kinases） co-activator WW45 （WW domain-containing adaptor 45）, Mstl, Mst2, or Lats2 （large tumor suppressor homologue 2） in mice result in over-grown hearts with elevated cardiomyocyte proliferation. Consistent with these observations, over-expression of YAP in the mouse embryonic heart increases heart size and promotes cardiac regeneration and contractility after myocardial infarction by inducing cardiomyocyte proliferation, whereas deletion of YAP in the mouse heart impedes cardiomyocyte proliferation, causing myocardial hypoplasia and embryonic or premature lethality. YAP has also been shown to play an important role in the vascular system. Specific-deletion of YAP from vascular smooth muscle cells in mice results in aberrant development of large arteries with a hypoplastic arterial wall phenotype. Hippo-YAP signaling cross-talks with other signaling pathways such as IGF （insulin-like growth factor） and Wnt signaling to promote heart growth by increasing expression of cell cycle genes. The purpose of this review is to summarize these recent findings and discuss potential diagnostic or therapeutic strategies in cardiovascular system based on manipulating the Hippo-YAP signaling.
Mapping the chromatin occupancy of transcription factors (TFs) is a key step in deciphering developmental transcriptional programs. Here we use biotinylated knockin alleles of seven key cardiac TFs ...(GATA4, NKX2-5, MEF2A, MEF2C, SRF, TBX5, TEAD1) to sensitively and reproducibly map their genome-wide occupancy in the fetal and adult mouse heart. These maps show that TF occupancy is dynamic between developmental stages and that multiple TFs often collaboratively occupy the same chromatin region through indirect cooperativity. Multi-TF regions exhibit features of functional regulatory elements, including evolutionary conservation, chromatin accessibility, and activity in transcriptional enhancer assays. H3K27ac, a feature of many enhancers, incompletely overlaps multi-TF regions, and multi-TF regions lacking H3K27ac retain conservation and enhancer activity. TEAD1 is a core component of the cardiac transcriptional network, co-occupying cardiac regulatory regions and controlling cardiomyocyte-specific gene functions. Our study provides a resource for deciphering the cardiac transcriptional regulatory network and gaining insights into the molecular mechanisms governing heart development.
YAP (yes-associated protein), a key transcriptional co-factor that is negatively regulated by the Hippo pathway, is crucial for the development and size control of multiple organs, including the ...liver. However, its role in the brain remains unclear. Here, we provide evidence for YAP regulation of mouse neocortical astrocytic differentiation and proliferation. YAP was undetectable in neurons, but selectively expressed in neural stem cells (NSCs) and astrocytes. YAP in NSCs was required for neocortical astrocytic differentiation, with no apparent role in self-renewal or neural differentiation. However, YAP in astrocytes was necessary for astrocytic proliferation. Yap (Yap1) knockout, Yap(nestin) conditional knockout and Yap(GFAP) conditional knockout mice displayed fewer neocortical astrocytes and impaired astrocytic proliferation and, consequently, death of neocortical neurons. Mechanistically, YAP was activated by BMP2, and the active/nuclear YAP was crucial for BMP2 induction and stabilization of SMAD1 and astrocytic differentiation. Expression of SMAD1 in YAP-deficient NSCs partially rescued the astrocytic differentiation deficit in response to BMP2. Taken together, these results identify a novel function of YAP in neocortical astrocytic differentiation and proliferation, and reveal a BMP2-YAP-SMAD1 pathway underlying astrocytic differentiation in the developing mouse neocortex.
Clustering technology is one of the crucial technologies to prolong the lifetime in wireless sensor networks. However, most cluster schemes choose cluster head randomly to send data without ...considering load balancing and security. In addition, some cluster heads in the highly active area may be overloaded, while others in the low active area may be overloaded, which may easily lead to extreme imbalance in task allocation. Our research on relevant literature shows that the existing authentication schemes do not fully consider the load balancing of cluster heads, while the load balancing schemes ignore the security authentication of cluster heads. Therefore, this article effectively combines load balancing and security verification, and proposes a lightweight load balancing and verification scheme (secure load and energy balancing) based on clustered wireless sensor networks. Secure load and energy balancing implements cluster head’s authentication and confidentiality and integrity of all messages in load balancing. This scheme not only effectively maintains the energy balance of the whole network but also successfully improves the security overhead, thus prolonging the network lifetime. The simulation results show that compared with other similar schemes, this scheme has higher packet forwarding rate, longer network life, and lower overhead. This further proves that the scheme is energy-saving, safe, dynamic, stable, and sustainable.
The Hippo signaling effector, TEAD1 plays an essential role in cardiovascular development. However, a role for TEAD1 in postmitotic cardiomyocytes (CMs) remains incompletely understood. Herein we ...reported that TEAD1 is required for postmitotic CM survival. We found that adult mice with ubiquitous or CM-specific loss of Tead1 present with a rapid lethality due to an acute-onset dilated cardiomyopathy. Surprisingly, deletion of Tead1 activated the necroptotic pathway and induced massive cardiomyocyte necroptosis, but not apoptosis. In contrast to apoptosis, necroptosis is a pro-inflammatory form of cell death and consistent with this, dramatically higher levels of markers of activated macrophages and pro-inflammatory cytokines were observed in the hearts of Tead1 knockout mice. Blocking necroptosis by administration of necrostatin-1 rescued Tead1 deletion-induced heart failure. Mechanistically, genome-wide transcriptome and ChIP-seq analysis revealed that in adult hearts, Tead1 directly activates a large set of nuclear DNA-encoded mitochondrial genes required for assembly of the electron transfer complex and the production of ATP. Loss of Tead1 expression in adult CMs increased mitochondrial reactive oxygen species, disrupted the structure of mitochondria, reduced complex I-IV driven oxygen consumption and ATP levels, resulting in the activation of necroptosis. This study identifies an unexpected paradigm in which TEAD1 is essential for postmitotic CM survival by maintaining the expression of nuclear DNA-encoded mitochondrial genes required for ATP synthesis.
One concerned issue in the routing protocol for wireless sensor networks (WSNs) is how to provide with as much security to some special applications as possible. Another is how to make full use of ...the severely limited resource presented by WSNs. The existing routing protocols in the recent literatures focus either only on addressing security issues while expending much power or only on improving lifetime of network. None of them efficiently combine the above-mentioned two challenges to one integrated solutions. In this paper, we propose efficient and secure routing protocol based on encryption and authentication for WSNs: BEARP, which consists of three phases: neighbor discovery phase, routing discovery phase, and routing maintenance phase. BEARP encrypts all communication packets and authenticates the source nodes and the base station (BS), and it ensures the four security features including routing information confidentiality, authentication, integrity, and freshness. Furthermore, we still design routing path selection system, intrusion detection system, and the multiple-threaded process mechanism for BEARP. Thus, all the secure mechanisms are united together to effectively resist some typical attacks including selective forwarding attack, wormhole attacks, sinkhole attacks, and even a node captured. Our BEARP especially mitigates the loads of sensor nodes by transferring routing related tasks to BS, which not only maintains network wide energy equivalence and prolongs network lifetime but also improves our security mechanism performed uniquely by the secure BS. Simulation results show a favorable increase in performance for BEARP when compared with directed diffusion protocol and secure directed diffusion protocol in the presence of compromised nodes.
A room‐temperature‐stable crystalline cyclic (alkyl)(amino)nitrenium cation 2 features cationic nitrogen atom with a smaller HOMO–LUMO gap compared to that of a 1,2,3‐triazolium 5 (an N‐heterocyclic ...nitrenium cation). The low‐lying LUMO of 2 results in an enhanced electrophilicity, which allowed for the formation of Lewis adducts with neutral Lewis bases, such as Me3P, nBu3P, and IiPr. The N‐based Lewis acid 2 also forms an FLP with tBu3P but subsequently reacts with (PrS)2 to cleave the S−S bond. Both experimental and theoretical results suggest that the Lewis acidity of 2 is stronger than its N3 analogues.
The room‐temperature‐stable crystalline cyclic (alkyl)(amino) nitrenium features a cationic nitrogen atom and exhibits enhanced electrophilicity, yielding Lewis adducts with Me3P, nBu3P, and IiPr and an FLP with tBu3P.
The scandium complex bearing both methylidene and phosphinidene ligands, (LSc)2(μ2-CH2)(μ2-PDIPP) (L = MeC(NDIPP)CHC(NDIPP)Me−, DIPP = 2,6-( i Pr)2C6H3) (2), has been synthesized, and its ...reactivity has been investigated. Reaction of scandium methyl phosphide LSc(Me){P(H)DIPP} with 1 equiv of scandium dimethyl complex LScMe2 in toluene at 60 °C provided complex 2 in good yield, and the structure of complex 2 was determined by single-crystal X-ray diffraction. Complex 2 easily undergoes nucleophilic addition reactions with CO2, CS2, benzonitrile, and tert-butyl isocyanide. In the above reactions, the unsaturated substrates insert into the Sc–C(methylidene) bond to give some interesting dianionic ligands while the Sc–P(phosphinidene) bond remains untouched. The bonding situation of complex 2 was analyzed using DFT methods, indicating a more covalent bond between the scandium ion and the phosphinidene ligand than between the scandium ion and the methylidene ligand.
Our previous study has shown that yes-associated protein (YAP) plays a crucial role in the phenotypic modulation of vascular smooth muscle cells (SMCs) in response to arterial injury. However, the ...role of YAP in vascular SMC development is unknown.
The goal of this study was to investigate the functional role of YAP in cardiovascular development in mice and determine the mechanisms underlying YAP's actions.
YAP was deleted in cardiomyocytes and vascular SMCs by crossing YAP flox mice with SM22α-Cre transgenic mice. Cardiac/SMC-specific deletion of YAP directed by SM22α-Cre resulted in perinatal lethality in mice because of profound cardiac defects including hypoplastic myocardium, membranous ventricular septal defect, and double outlet right ventricle. The cardiac/SMC-specific YAP knockout mice also displayed severe vascular abnormalities including hypoplastic arterial wall, short/absent brachiocephalic artery, and retroesophageal right subclavian artery. Deletion of YAP in mouse vascular SMCs induced expression of a subset of cell cycle arrest genes including G-protein-coupled receptor 132 (Gpr132). Silencing Gpr132 promoted SMC proliferation, whereas overexpression of Gpr132 attenuated SMC growth by arresting cell cycle in G0/G1 phase, suggesting that ablation of YAP-induced impairment of SMC proliferation was mediated, at least in part, by induction of Gpr132 expression. Mechanistically, YAP recruited the epigenetic repressor histone deacetylase-4 to suppress Gpr132 gene expression via a muscle CAT element in the Gpr132 gene.
YAP plays a critical role in cardiac/SMC proliferation during cardiovascular development by epigenetically regulating expression of a set of cell cycle suppressors.
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