Presenilin 1 Is a Therapeutic Target in Pulmonary Hypertension and Promotes Vascular Remodeling.

Small muscular pulmonary artery remodeling is a dominant feature of pulmonary arterial hypertension (PAH). PSEN1 affects angiogenesis, cancer, and Alzheimer's disease. We aimed to determine the role of PSEN1 in the pathogenesis of vascular remodeling in pulmonary hypertension (PH). Hemodynamics and vascular remodeling in the Psen1-knockin and smooth muscle-specific Psen1-knockout mice were assessed. The functional partners of PSEN1 were predicted by bioinformatics analysis and biochemical experiments. The therapeutic effect of PH was evaluated by administration of the PSEN1-specific inhibitor ELN318463. We discovered that both the mRNA and protein levels of PSEN1 were increased over time in hypoxic rats, monocrotaline rats, and Su5416/hypoxia mice. Psen1 transgenic mice were highly susceptible to PH, whereas smooth muscle-specific Psen1-knockout mice were resistant to hypoxic PH. STRING analysis showed that Notch1/2/3, ß-catenin, Cadherin-1, DNER (delta/notch-like epidermal growth factor-related receptor), TMP10, and ERBB4 appeared to be highly correlated with PSEN1. Immunoprecipitation confirmed that PSEN1 interacts with ß-catenin and DNER, and these interactions were suppressed by the catalytic PSEN1 mutations D257A, D385A, and C410Y. PSEN1 was found to mediate the nuclear translocation of the Notch1 intracellular domains and activated RBP-Jκ. Octaarginine-coated liposome-mediated pharmacological inhibition of PSEN1 significantly prevented and reversed the pathological process in hypoxic and monocrotaline-induced PH. PSEN1 essentially drives the pathogenesis of PAH and interacted with the noncanonical Notch ligand DNER. PSEN1 can be used as a promising molecular target for treating PAH. PSEN1 inhibitor ELN318463 can prevent and reverse the progression of PH and can be developed as a potential anti-PAH drug.

Role of lncRNAs in cis- and trans-regulatory responses to salt in Populus trichocarpa.

Long non-coding RNAs (lncRNAs) are emerging as versatile regulators in diverse biological processes. However, little is known about their cis- and trans-regulatory contributions in gene expression under salt stress. Using 27 RNA-seq data sets from Populus trichocarpa leaves, stems and roots, we identified 2988 high-confidence lncRNAs, including 1183 salt-induced differentially expressed lncRNAs. Among them, 301 lncRNAs have potential for positively affecting their neighboring genes, predominantly in a cis-regulatory manner rather than by co-transcription. Additionally, a co-expression network identified six striking salt-associated modules with a total of 5639 genes, including 426 lncRNAs, and in these lncRNA sequences, the DNA/RNA binding motifs are enriched. This suggests that lncRNAs might contribute to distant gene expression of the salt-associated modules in a trans-regulatory manner. Moreover, we found 30 lncRNAs that have potential to simultaneously cis- and trans-regulate salt-responsive homologous genes, and Ptlinc-NAC72, significantly induced under long-term salt stress, was selected for validating its regulation of the expression and functional roles of the homologs PtNAC72.A and PtNAC72.B (PtNAC72.A/B). The transient transformation of Ptlinc-NAC72 and a dual-luciferase assay of Ptlinc-NAC72 and PtNAC72.A/B promoters confirmed that Ptlinc-NAC72 can directly upregulate PtNAC72.A/B expression, and a presence/absence assay was further conducted to show that the regulation is probably mediated by Ptlinc-NAC72 recognizing the tandem elements (GAAAAA) in the PtNAC72.A/B 5' untranslated region (5'-UTR). Finally, the overexpression of Ptlinc-NAC72 produces a hypersensitive phenotype under salt stress. Altogether, our results shed light on the cis- and trans-regulation of gene expression by lncRNAs in Populus and provides an example of long-term salt-induced Ptlinc-NAC72 that could be used to mitigate growth costs by conferring plant resilience to salt stress.

Circular RNA Calm4 Regulates Hypoxia-Induced Pulmonary Arterial Smooth Muscle Cells Pyroptosis via the Circ-Calm4/miR-124-3p/PDCD6 Axis.

[Figure: see text].

lnc-Rps4l-encoded peptide RPS4XL regulates RPS6 phosphorylation and inhibits the proliferation of PASMCs caused by hypoxia.

Pulmonary artery smooth muscle cells (PASMCs) proliferation caused by hypoxia is an important pathological process of pulmonary hypertension (PH). Prevention of PASMCs proliferation can effectively reduce PH mortality. Long non-coding RNAs (lncRNAs) are involved in the proliferation process. Recent evidence has demonstrated that functional peptides encoded by lncRNAs play important roles in cell pathophysiological process. Our previous study has demonstrated that lnc-Rps4l with high coding ability mediates the PASMCs proliferation under hypoxic conditions. We hypothesize in this study that a lnc-Rps4l-encoded peptide is involved in hypoxic-induced PASMCs proliferation. The presence of peptide 40S ribosomal protein S4 X isoform-like (RPS4XL) encoded by lnc-Rps4l in PASMCs under hypoxic conditions was confirmed by bioinformatics, immunofluorescence, and immunohistochemistry. Inhibition of proliferation by the peptide RPS4XL was demonstrated in hypoxic PASMCs by MTT, bromodeoxyuridine (BrdU) incorporation, and immunofluorescence assays. By using the bioinformatics, coimmunoprecipitation (coIP), and mass spectrometry, RPS6 was identified to interact with RPS4XL. Furthermore, lnc-Rps4l-encoded peptide RPS4XL inhibited the RPS6 process via binding to RPS6 and inhibiting RPS6 phosphorylation at p-RPS6 (Ser240+Ser244) phosphorylation site. These results systematically elucidate the role and regulatory network of Rps4l-encoded peptide RPS4XL in PASMCs proliferation. These discoveries provide potential targets for early diagnosis and a leading compound for treatment of hypoxic PH.

Lanosterol reverses protein aggregation in cataracts.

The human lens is comprised largely of crystallin proteins assembled into a highly ordered, interactive macro-structure essential for lens transparency and refractive index. Any disruption of intra- or inter-protein interactions will alter this delicate structure, exposing hydrophobic surfaces, with consequent protein aggregation and cataract formation. Cataracts are the most common cause of blindness worldwide, affecting tens of millions of people, and currently the only treatment is surgical removal of cataractous lenses. The precise mechanisms by which lens proteins both prevent aggregation and maintain lens transparency are largely unknown. Lanosterol is an amphipathic molecule enriched in the lens. It is synthesized by lanosterol synthase (LSS) in a key cyclization reaction of a cholesterol synthesis pathway. Here we identify two distinct homozygous LSS missense mutations (W581R and G588S) in two families with extensive congenital cataracts. Both of these mutations affect highly conserved amino acid residues and impair key catalytic functions of LSS. Engineered expression of wild-type, but not mutant, LSS prevents intracellular protein aggregation of various cataract-causing mutant crystallins. Treatment by lanosterol, but not cholesterol, significantly decreased preformed protein aggregates both in vitro and in cell-transfection experiments. We further show that lanosterol treatment could reduce cataract severity and increase transparency in dissected rabbit cataractous lenses in vitro and cataract severity in vivo in dogs. Our study identifies lanosterol as a key molecule in the prevention of lens protein aggregation and points to a novel strategy for cataract prevention and treatment.

The SR Splicing Factors: Providing Perspectives on Their Evolution, Expression, Alternative Splicing, and Function in Populus trichocarpa.

Serine/arginine-rich (SR) proteins are important splicing factors in plant development and abiotic/hormone-related stresses. However, evidence that SR proteins contribute to the process in woody plants has been lacking. Using phylogenetics, gene synteny, transgenic experiments, and RNA-seq analysis, we identified 24 PtSR genes and explored their evolution, expression, and function in Popolus trichocarpa. The PtSR genes were divided into six subfamilies, generated by at least two events of genome triplication and duplication. Notably, they were constitutively expressed in roots, stems, and leaves, demonstrating their fundamental role in P. trichocarpa. Additionally, most PtSR genes (~83%) responded to at least one stress (cold, drought, salt, SA, MeJA, or ABA), and, especially, cold stress induced a dramatic perturbation in the expression and/or alternative splicing (AS) of 18 PtSR genes (~75%). Evidentially, the overexpression of PtSCL30 in Arabidopsis decreased freezing tolerance, which probably resulted from AS changes of the genes (e.g., ICE2 and COR15A) critical for cold tolerance. Moreover, the transgenic plants were salt-hypersensitive at the germination stage. These indicate that PtSCL30 may act as a negative regulator under cold and salt stress. Altogether, this study sheds light on the evolution, expression, and AS of PtSR genes, and the functional mechanisms of PtSCL30 in woody plants.

Programmed death-ligand 1 triggers PASMCs pyroptosis and pulmonary vascular fibrosis in pulmonary hypertension.

Pyroptosis is a pro-inflammatory form of programmed cell death, whose genesis directly depended on caspase-1 activation. Pulmonary hypertension (PH) is a disease characterized, in part, by vascular fibrosis. Up to now, there is no report on the relationship between pyroptosis and vascular fibrosis in PH. Here, we confirmed that pyroptosis had occurred in the media of pulmonary arteries in two PH rat models and hypoxic human pulmonary arterial smooth muscle cells (hPASMCs). Caspase-1 inhibition attenuated the pathogenesis of PH, as assessed by vascular remodeling, right ventricular systolic pressure, right ventricle hypertrophy and hemodynamic parameters of pulmonary vasculature. Moreover, caspase-1 inhibition suppressed pulmonary vascular fibrosis as demonstrated by Masson staining, as well as immunohistochemistry and Western blot analysis of fibrillar collagen. In addition, Programmed death-ligand 1 (PD-L1) was markedly increased in PH, which was regulated by the transcription factor STAT1. Furthermore, PD-L1 knockdown in hPASMCs repressed the onset of hypoxia-induced pyroptosis and fibrosis. Overall, these data identify a critical STAT1-dependent posttranscriptional modification that promotes PD-L1 expression in the pyroptosis of PASMCs to modulate pulmonary vascular fibrosis and accelerate the progression of PH.

Dexmedetomidine Inhibits Neuroinflammation by Altering Microglial M1/M2 Polarization Through MAPK/ERK Pathway.

Neuroinflammation is critical in the pathogenesis of neurological diseases. Microglial pro-inflammatory (M1) and anti-inflammatory (M2) status determines the outcome of neuroinflammation. Dexmedetomidine exerts anti-inflammatory effects in many neurological conditions. Whether dexmedetomidine functions via modulation of microglia M1/M2 polarization remains to be fully elucidated. In the present study, we investigated the anti-inflammatory effects of dexmedetomidine on the neuroinflammatory cell model and explored the potential mechanism. BV2 cells were stimulated with LPS to establish a neuroinflammatory model. The cell viability was determined with MTT assay. NO levels were assessed using a NO detection kit. The protein levels of IL-10, TNF-α, iNOS, CD206, ERK1/2, and pERK1/2 were quantified using Western blotting. LPS significantly increased pro-inflammatory factors TNF-α and NO, and M1 phenotypic marker iNOS, and decreased anti-inflammatory factor IL-10 and M2 phenotypic marker CD206 in BV2 cells. Furthermore, exposure of BV2 cells to LPS significantly raised pERK1/2 expression. Pretreatment with dexmedetomidine attenuated LPS-elicited changes in p-ERK, iNOS, TNF-α, NO, CD206 and IL-10 levels in BV2 cells. However, co-treatment with dexmedetomidine and LM22B-10, an agonist of ERK, reversed dexmedetomidine-elicited changes in p-ERK, iNOS, TNF-α, NO, CD206 and IL-10 levels in LPS-exposed BV2 cells. We, for the first time, showed that dexmedetomidine increases microglial M2 polarization by inhibiting phosphorylation of ERK1/2, by which it exerts anti-inflammatory effects in BV2 cells.

Edaravone protects primary-cultured rat cortical neurons from ketamine-induced apoptosis via reducing oxidative stress and activating PI3K/Akt signal pathway.

Ketamine caused neuroapoptosis in the development of rat brain, in which oxidative stress play an important role. Edaravone (3-methyl-1-phenyl-2-pyrazolin-5-one), a free radical scavenger, exerts neuroprotective effects in many neurological disease models. Here we investigated whether edaravone protects primary-cultured neurons against ketamine-induced apoptosis and its potential mechanism. Edaravone increased neuronal viability, decreased neuronal apoptosis, increased the ratio of Bcl-2/Bax after ketamine exposure. Edaravone also increased superoxide dismutase (SOD) activity and decreased malondialdehyde (MDA) level in ketamine-exposed neurons. In addition, edaravone increased protein levels of phosphorylated-protein kinase B (p-Akt), phosphorylated-glycogen synthase kinase-3ß (p-GSK-3ß) and phosphorylated-forkhead box protein O1 (p-FoxO1) in ketamine-exposed neurons. The neuroprotective effects of edaravone were reversed by LY294002, a specific phosphatidylinositol 3-kinase (PI3K) inhibitor. These findings demonstrated that edaravone protected neurons against ketamine-induced apoptosis by diminishing oxidative stress and activating PI3K/Akt signal pathway.

Lipopolysaccharide-induced proliferation and glycolysis in airway smooth muscle cells via activation of Drp1.

Abnormal airway smooth muscle cells (ASMCs) proliferation is an important pathological process in airway remodeling contributes to increased mortality in asthma. Mitochondrial dynamics and metabolism have a central role in the maintenance of the cell function. In this study, lipopolysaccharide (LPS)-induced ASMCs proliferative model was used to investigate the effect of mitochondria on the proliferation of ASMCs and the possible mechanism. We used cell and molecular biology to determine the effect of dynamin-related protein 1 (Drp1) on LPS-mediated ASMCs cell cycle progression and glycolysis. The major findings of the current study are as follows: LPS promoted an increased mitochondrial fission and phosphorylation of Drp1 at Ser616 (p-Drp1 Ser616). LPS-induced ASMCs proliferation and cell cycle progression, which was significantly inhibited application of Drp1 RNA interfering. Glycolysis inhibitor 2-deoxyglucose (2-DG) depressed ASMCs proliferative process induced by LPS stimulation. LPS caused mitochondrial metabolism disorders and aerobic glycolysis in a dependent on Drp1 activation. These results indicated that Drp1 may function as a key factor in asthma airway remodeling by mediating ASMC proliferation and cell cycle acceleration through an effect on mitochondrial metabolic disturbance.

CLCuMuB ßC1 Subverts Ubiquitination by Interacting with NbSKP1s to Enhance Geminivirus Infection in Nicotiana benthamiana.

Viruses interfere with and usurp host machinery and circumvent defense responses to create a suitable cellular environment for successful infection. This is usually achieved through interactions between viral proteins and host factors. Geminiviruses are a group of plant-infecting DNA viruses, of which some contain a betasatellite, known as DNAß. Here, we report that Cotton leaf curl Multan virus (CLCuMuV) uses its sole satellite-encoded protein ßC1 to regulate the plant ubiquitination pathway for effective infection. We found that CLCuMu betasatellite (CLCuMuB) ßC1 interacts with NbSKP1, and interrupts the interaction of NbSKP1s with NbCUL1. Silencing of either NbSKP1s or NbCUL1 enhances the accumulation of CLCuMuV genomic DNA and results in severe disease symptoms in plants. ßC1 impairs the integrity of SCFCOI1 and the stabilization of GAI, a substrate of the SCFSYL1 to hinder responses to jasmonates (JA) and gibberellins (GA). Moreover, JA treatment reduces viral accumulation and symptoms. These results suggest that CLCuMuB ßC1 inhibits the ubiquitination function of SCF E3 ligases through interacting with NbSKP1s to enhance CLCuMuV infection and symptom induction in plants.

Hypoxia inhibits pulmonary artery endothelial cell apoptosis via the e-selectin/biliverdin reductase pathway.

Hypoxia-induced inhibition of apoptosis in pulmonary artery endothelial cells (PAECs) has an important role in pulmonary arterial remodeling leading to aggravated hypoxic pulmonary arterial hypertension. However, the mechanisms involved in the hypoxia-induced inhibition of PAEC apoptosis have not been elucidated. e-selectin and biliverdin reductase (BVR) have been reported to contribute to the cascade of apoptosis in several cell lines but not in PAECs. In the present study, we show that the expression of e-selectin and BVR was both up-regulated by hypoxia in PAECs. Moreover, hypoxia attenuated the decreased cell survival and apoptotic protein expression, and increased DNA fragmentation induced by serum deprivation in the PAECs, which was mediated by the e-selectin/BVR pathway. In addition, by examining the mitochondrial membrane potential and mitochondrial membrane proteins (Bcl-2 and BAX), we show that the mitochondrial-dependent apoptosis pathway was necessary for the e-selectin/BVR pathway inducing the anti-apoptotic effect of hypoxia in PAECs. Taken all together, our data show that the e-selectin/BVR pathway participates in the inhibitory process of hypoxia in PAEC apoptosis which is mediated by the mitochondrial-dependent apoptosis pathway.

15-Lipoxygenase and 15-hydroxyeicosatetraenoic acid regulate intravascular thrombosis in pulmonary hypertension.

Pulmonary arterial hypertension (PAH) is a disease characterized by thickening of pulmonary artery walls, elevated pulmonary vascular resistance, pulmonary vascular thrombotic lesions, and right heart failure. Recent studies suggest that 15-lipoxygenase (15-LO)/15-hydroxyeicosatetraenoic acid (15-HETE) play an important role in PAH, acting on arterial walls. Here, we show evidence for the action of the 15-LO/15-HETE signaling in the pulmonary vascular thrombotic lesions in the experimental PAH models. Platelet deposition was augmented in rats exposed to hypoxia and Sugen 5416, which were both prevented by nordihydroguaiaretic acid (NDGA), a 15-LO inhibitor. Chronic hypoxic resulted in the platelet deposition specifically in pulmonary vasculature, which was reversed by 15-LO inhibitor. The 15-LO pathway mediated in the endothelial dysfunction induced by hypoxia in vivo. Meanwhile, 15-HETE positively regulated the generation of IL-6 and monocyte chemoattractant protein-1 (MCP-1). The coagulation and platelet activation induced by hypoxia were reversed by 15-LO inhibitor NDGA or the MCP-1 inhibitor synthesis inhibitor bindarit in rats. The 15-LO/15-HETE signaling promoted the coagulation and platelet activation, which was suppressed by MCP-1 inhibition. These results therefore suggest that 15-LO/15-HETE signaling plays a role in platelet activation and pulmonary vascular thrombosis in PAH, involving MCP-1.

Super enhancer-associated circRNA-circLrch3 regulates hypoxia-induced pulmonary arterial smooth muscle cells pyroptosis by formation of R-loop with host gene.

BACKGROUND: Pulmonary hypertension (PH) is a complex vascular disorder, characterized by pulmonary vessel remodeling and perivascular inflammation. Pulmonary arterial smooth muscle cells (PASMCs) pyroptosis is a novel pathological mechanism implicated of pulmonary vessel remodeling. However, the involvement of circRNAs in the process of pyroptosis and the underlying regulatory mechanisms remain inadequately understood. METHODS: Western blotting, PI staining and LDH release were used to explore the role of circLrch3 in PASMCs pyroptosis. Moreover, S9.6 dot blot and DRIP-PCR were used to assess the formation of R-loop between circLrch3 and its host gene Lrch3. Chip-qPCR were used to evaluate the mechanism of super enhancer-associated circLrh3, which is transcriptionally activated by the transcription factor Tbx2. RESULTS: CircLrch3 was markedly upregulated in hypoxic PASMCs. CircLrch3 knockdown inhibited hypoxia induced PASMCs pyroptosis in vivo and in vitro. Mechanistically, circLrch3 can form R-loop with host gene to upregulate the protein and mRNA expression of Lrch3. Furthermore, super enhancer interacted with the Tbx2 at the Lrch3 promoter locus, mediating the augmented transcription of circLrch3. CONCLUSION: Our findings clarify the role of a super enhancer-associated circLrch3 in the formation of R-loop with the host gene Lrch3 to modulate pyroptosis in PASMCs, ultimately promoting the development of PH.

Transcriptome analysis provides StMYBA1 gene that regulates potato anthocyanin biosynthesis by activating structural genes.

Anthocyanin biosynthesis is affected by light, temperature, and other environmental factors. The regulation mode of light on anthocyanin synthesis in apple, pear, tomato and other species has been reported, while not clear in potato. In this study, potato RM-210 tubers whose peel will turn purple gradually after exposure to light were selected. Transcriptome analysis was performed on RM-210 tubers during anthocyanin accumulation. The expression of StMYBA1 gene continued to increase during the anthocyanin accumulation in RM-210 tubers. Moreover, co-expression cluster analysis of differentially expressed genes showed that the expression patterns of StMYBA1 gene were highly correlated with structural genes CHS and CHI. The promoter activity of StMYBA1 was significantly higher in light conditions, and StMYBA1 could activate the promoter activity of structural genes StCHS, StCHI, and StF3H. Further gene function analysis found that overexpression of StMYBA1 gene could promote anthocyanin accumulation and structural gene expression in potato leaves. These results demonstrated that StMYBA1 gene promoted potato anthocyanin biosynthesis by activating the expression of structural genes under light conditions. These findings provide a theoretical basis and genetic resources for the regulatory mechanism of potato anthocyanin synthesis.

A phylotranscriptomic dataset of angiosperm species under cold stress.

Angiosperms are one of the most diverse and abundant plant groups that are widely distributed on Earth, from tropical to temperate and polar zones. The wide distribution of angiosperms may be attributed to the evolution of sophisticated mechanisms of environmental adaptability, including cold tolerance. Since the development of high-throughput sequencing, transcriptome has been widely utilized to gain insights into the molecular mechanisms of plants in response to cold stress. However, previous studies generally focused on single or two species, and comparative transcriptome analyses for multispecies responding to cold stress were limited. In this study, we selected 11 representative angiosperm species, performed phylotranscriptome experiments at four time points before and after cold stress, and presented a profile of cold-induced transcriptome changes in angiosperms. Our multispecies cold-responsive RNA-seq datasets provide valuable references for exploring conserved and evolutionary mechanisms of angiosperms in adaptation to cold stress.

Orthogroup and phylotranscriptomic analyses identify transcription factors involved in the plant cold response: A case study of Arabidopsis BBX29.

C-repeat binding factors (CBFs) are well-known transcription factors (TFs) that regulate plant cold acclimation. RNA sequencing (RNA-seq) data from diverse plant species provide opportunities to identify other TFs involved in the cold response. However, this task is challenging because gene gain and loss has led to an intertwined community of co-orthologs and in-paralogs between and within species. Using orthogroup (closely related homologs) analysis, we identified 10,549 orthogroups in five representative eudicots. A phylotranscriptomic analysis of cold-treated seedlings from eudicots identified 35 high-confidence conserved cold-responsive transcription factor orthogroups (CoCoFos). These 35 CoCoFos included the well-known cold-responsive regulators CBFs, HSFC1, ZAT6/10, and CZF1 among others. We used Arabidopsis BBX29 for experimental validation. Expression and genetic analyses showed that cold-induction of BBX29 is CBF- and abscisic acid-independent, and BBX29 is a negative regulator of cold tolerance. Integrative RNA-seq and Cleavage Under Targets and Tagmentation followed by sequencing analyses revealed that BBX29 represses a set of cold-induced TFs (ZAT12, PRR9, RVE1, MYB96, etc.). Altogether, our analysis yielded a library of eudicot CoCoFos and demonstrated that BBX29 is a negative regulator of cold tolerance in Arabidopsis.

Methylation level of potato gene OMT30376 regulates tuber anthocyanin transformations.

After anthocyanin synthesis, a variety of anthocyanin compounds are produced through further methylation, glycosylation, and acylation. However, the effect of the potato methylase gene on anthocyanin biosynthesis has not been reported. Red and purple mutation types appear in tubers of the potato cultivar 'Purple Viking' with chimeric skin phenotypes. In this study, transcriptome and anthocyanin metabolome analyses were performed on skin of Purple Viking tubers and associated mutants. According to the metabolome analysis, the transformation of delphinidin into malvidin-3-O-glucoside and petunidin 3-O-glucoside and that of cyanidin into rosinidin O-hexoside and peonidin-3-O-glucoside were hindered in red tubers. Expression of methyltransferase gene OMT30376 was significantly lower in red tubers than in purple ones, whereas the methylation level of OMT30376 was significantly higher in red tubers. In addition, red skin appeared in tubers from purple tuber plants treated with S-adenosylmethionine (SAM), indicating the difference between purple and red was caused by the methylation degree of the gene OMT30376. Thus, the results of the study suggest that the OMT30376 gene is involved in the transformation of anthocyanins in potato tubers. The results also provide an important reference to reveal the regulatory mechanisms of anthocyanin biosynthesis and transformation.