Pertussis Toxin-sensitive Activation of Phospholipase C by the C5a and fMet-Leu-Phe Receptors

Signal transduction pathways that mediate C5a and fMet-Leu-Phe (fMLP)-induced pertussis toxin (PTx)-sensitive activation of phospholipase C (PLC) have been investigated using a cotransfection assay system in COS-7 cells. The abilities of the receptors for C5a and fMLP to activate PLC beta 2 and PLC beta 3 through the Gbeta gamma subunits of endogenous Gi proteins in COS-7 cells were tested because both PLC beta 2 and PLC beta 3 were shown to be activated by the beta gamma subunits of G proteins in in vitro reconstitution assays. Neither of the receptors can activate endogenous PLC beta 3 or recombinant PLC beta 3 in transfected COS-7 cells. However, both receptors can clearly activate PLC beta 2 in a PTx-sensitive manner, suggesting that the receptors may interact with endogenous PTx-sensitive G proteins and activate PLC beta 2 probably through the Gbeta gamma subunits. These findings were further corroborated by the results that PLC beta 3 could only be slightly activated by Gbeta 1gamma 1 or Gbeta 1gamma 5 in the cotransfection assay, whereas the Gbeta gamma subunits strongly activated PLC beta 2 under the same conditions. PLC beta 3 can be activated by Galpha q, Galpha 11, and Galpha 16 in the cotransfection assay. In addition, the Ggamma 2 and Ggamma 3 mutants with substitution of the C-terminal Cys residue by a Ser residue, which can inhibit wild type Gbeta gamma -mediated activation of PLC beta 2, were able to inhibit C5a or fMLP-mediated activation of PLC beta 2. These Ggamma mutants, however, showed little effect on m1-muscarinic receptor-mediated PLC activation, which is mediated by the Gq class of G proteins. These results all confirm that the Gbeta gamma subunits are involved in PLC beta 2 activation by the two chemoattractant receptors and suggest that in COS-7 cells activation of PLC beta 3 by Gbeta gamma may not be the primary pathway for the receptors

Inocellia (Amurinocellia) calida (Raphidioptera, Inocelliidae) was first observed as a predator of Monochamus saltuarius (Coleoptera, Cerambycidae) in China, the vector of Bursaphelenchus xylophilus (Aphelenchida, Aphelenchoididae)

Monochamus saltuarius Gebler (Coleoptera, Cerambycidae) serves as the primary carrier of Bursaphelenchus xylophilus (Steiner & Buhrer) (Aphelenchida, Aphelenchoididae) in the middle-temperate zone of China. Pine wilt disease caused by B. xylophilus leads to serious losses to pine forestry around the world. It is necessary to study the biological control of M. saltuarius to effectively prevent the further spread of B. xylophilus. To explore the insect resources that act as natural enemies of M. saltuarius, investigations were conducted on natural enemy insects by splitting Pinus koraiensis Siebold & Zucc (Pinales, Pinaceae) damaged by M. saltuarius and dissecting their trunks in Yingpan Village, Fushun County, Fushun City, Liaoning Province, China, in 2023. A larva of Inocellia (Amurinocellia) calida (H. Aspöck & U. Aspöck) (Raphidioptera, Inocelliidae) was discovered in the trunk of an infested P. koraiensis. Additionally, the feeding habits of I. calida were preliminarily examined under indoor conditions and a description of its morphological characteristics was provided. When placed in an indoor environment, the I. calida larva began pupating after a period of 21 days, during which time it consumed and attacked a total of 23 M. saltuarius larvae. Ultimately, after a pupal period of ten days, the I. calida larva emerged successfully as an adult. This discovery marks the first recorded presence of I. calida in Liaoning Province and the first documentation of I. calida in China, serving as a natural predatory enemy of M. saltuarius

Tumor innate immunity primed by specific interferon-stimulated endogenous retroviruses.

Mesenchymal tumor subpopulations secrete pro-tumorigenic cytokines and promote treatment resistance1-4. This phenomenon has been implicated in chemorefractory small cell lung cancer and resistance to targeted therapies5-8, but remains incompletely defined. Here, we identify a subclass of endogenous retroviruses (ERVs) that engages innate immune signaling in these cells. Stimulated 3 prime antisense retroviral coding sequences (SPARCS) are oriented inversely in 3' untranslated regions of specific genes enriched for regulation by STAT1 and EZH2. Derepression of these loci results in double-stranded RNA generation following IFN-γ exposure due to bi-directional transcription from the STAT1-activated gene promoter and the 5' long terminal repeat of the antisense ERV. Engagement of MAVS and STING activates downstream TBK1, IRF3, and STAT1 signaling, sustaining a positive feedback loop. SPARCS induction in human tumors is tightly associated with major histocompatibility complex class 1 expression, mesenchymal markers, and downregulation of chromatin modifying enzymes, including EZH2. Analysis of cell lines with high inducible SPARCS expression reveals strong association with an AXL/MET-positive mesenchymal cell state. While SPARCS-high tumors are immune infiltrated, they also exhibit multiple features of an immune-suppressed microenviroment. Together, these data unveil a subclass of ERVs whose derepression triggers pathologic innate immune signaling in cancer, with important implications for cancer immunotherapy

Roles of phospholipase C β2 in chemoattractant-elicited responses

The physiological roles of phospholipase C (PLC) β2 in hematopoiesis, leukocyte function, and host defense against infection were investigated using a mouse line that lacks PLC β2. PLC β2 deficiency did not affect hematopoiesis, but it blocked chemoattractant-induced Ca(2+) release, superoxide production, and MAC-1 up-regulation in neutrophils. In view of these effects, it was surprising that the absence of PLC β2 enhanced chemotaxis of different leukocyte populations and sensitized the in vivo response of the PLC β2-deficient mice to bacteria, viruses, and immune complexes. These data raise questions about the roles that PLC β2 may play in signal transduction induced by chemoattractants in leukocytes

Role of PsbV-Tyr137 in photosystem II studied by site-directed mutagenesis in the thermophilic cyanobacterium Thermosynechococcus vulcanus

PsbV (cytochrome c(550)) is one of the three extrinsic proteins of photosystem II (PSII) and functions to maintain the stability and activity of the Mn4CaO5 cluster, the catalytic center for water oxidation. PsbV-Y137 is the C-terminal residue of PsbV and is located at the exit of a hydrogen-bond network mediated by the D1-Y161-H190 residue pair. In order to examine the function of PsbV-Y137, four mutants, PsbV-Y137A, PsbV-Y137F, PsbV-Y137G, and PsbV-Y137W, were generated with Thermosynechococcus vulcanus (T. vulcanus). These mutants showed growth rates similar to that of the wild-type strain (WT); however, their oxygen-evolving activities were different. At pH 6.5, the oxygen evolution rates of Y137F and Y137W were almost identical to that of WT, whereas the oxygen evolution rates of the Y137A, Y137G mutants were 64% and 61% of WT, respectively. However, the oxygen evolution in the latter two mutants decreased less at higher pHs, suggesting that higher pHs facilitated oxygen evolution probably by facilitating proton egress in these two mutants. Furthermore, thylakoid membranes isolated from the PsbV-Y137A, PsbV-Y137G mutants exhibited much lower levels of oxygen-evolving activity than that of WT, which was found to be caused by the release of PsbV. In addition, PSII complexes purified from the PsbV-Y137A and PsbV-Y137G mutants lost all of the three extrinsic proteins but instead bind Psb27, an assembly cofactor of PSII. These results demonstrate that the PsbV-Tyr137 residue is required for the stable binding of PsbV to PSII, and the hydrogen-bond network mediated by D1-Y161-H190 is likely to function in proton egress during water oxidation

Genome-Wide Identification and Functional Characterization of GATA Transcription Factor Gene Family in <i>Alternaria alternata</i>

In the present study, we identified six GATA transcription factors (AaAreA, AaAreB, AaLreA, AaLreB, AaNsdD, and AaSreA) and characterized their functions in response to environmental stress and virulence in the tangerine pathotype of Alternaria alternata. The targeted gene knockout of each of the GATA-coding genes decreased the growth to varying degrees. The mutation of AaAreA, AaAreB, AaLreB, or AaNsdD decreased the conidiation. All the GATA transcription factors were found to be required for tolerance to cumyl hydroperoxide and tert-butyl-hydroperoxide (oxidants) and Congo red (a cell-wall-destructing agent). Pathogenicity assays assessed on detached citrus leaves revealed that mutations of AaAreA, AaLreA, AaLreB, or AaNsdD significantly decreased the fungal virulence. A comparative transcriptome analysis between the ∆AreA mutant and the wild-type strain revealed that the inactivation of AaAreA led to alterations in the expression of genes involved in a number of biological processes, including oxidoreductase activity, amino acid metabolism, and secondary metabolite biogenesis. Taken together, our findings revealed that GATA-coding genes play diverse roles in response to environmental stress and are important regulators involved in fungal development, conidiation, ROS detoxification, as well as pathogenesis. This study, for the first time, systemically underlines the critical role of GATA transcription factors in response to environmental stress and virulence in A. alternata

Function of PsbO-Asp158 in photosystem II: effects of mutation of this residue on the binding of PsbO and function of PSII in Thermosynechococcus vulcanus

PsbO-D158 is a highly conserved residue of the PsbO protein in photosystem II (PSII), and participates in one of the hydrogen-bonding networks connecting the manganese cluster with the lumenal surface. In order to examine the role of PsbO-D158, we mutated it to E, N or K in Thermosynechococcus vulcanus and characterized photosynthetic properties of the mutants obtained. The growth rates of these three mutants were similar to that of the wild type, whereas the oxygen-evolving activity of the three mutant cells decreased to 60-64% of the wild type. Fluorescence kinetics showed that the mutations did not affect the electron transfer from Q(A) to Q(B), but slightly affected the donor side of PSII. Moreover, all of the three mutant cells were more sensitive to high light and became slower to recover from photoinhibition. In the isolated thylakoid membranes from the three mutants, the PsbU subunit was lost and the oxygen-evolving activity was reduced to a lower level compared to that in the respective cells. PSII complexes isolated from these mutants showed no oxygen-evolving activity, which was found to be due to large or complete loss of PsbO, PsbV and PsbU during the process of purification. Moreover, PSII cores purified from the three mutants contained Psb27, an assembly co-factor of PSII. These results suggest that PsbO-D158 is required for the proper binding of the three extrinsic proteins to PSII and plays an important role in maintaining the optimal oxygen-evolving activity, and its mutation caused incomplete assembly of the PSII complex

The Mechanisms of Traditional Chinese Medicine Underlying the Prevention and Treatment of Parkinson's Disease

Parkinson's disease (PD), characterized with bradykinesia, static tremor, rigidity and disturbances in balance, is the second most common neurodegenerative disorder. Along with the largely aging population in the world, the incidence is increasing year by year, which imposes the negative impacts on patients, their families and the whole society. Traditional Chinese medicine (TCM) has a positive prospect for the prevention and cure of PD due to its advantages of less side effects and multi-target effects. At present, the pathogenesis of PD is not yet fully discovered. This paper elaborates the mechanisms of TCM underlying the prevention and treatment of PD with regards to the inhibition of oxidative stress, the regulation of mitochondrial dysfunction, the reduction of toxic excitatory amino acids (EAA), the inhibition of neuroinflammation, the inhibition of neuronal apoptosis, and the inhibition of abnormal protein aggregation