Redox-modulated SNX25 as a novel regulator of GPCR-G protein signaling from endosomes.

GPCR-G protein signaling from endosomes plays a crucial role in various physiological and pathological processes. However, the mechanism by which endosomal G protein signaling is terminated remains largely unknown. In this study, we aimed to investigate the regulatory mechanisms involved in terminating the signaling of Gα subunits from endosomes. Through structural analysis and cell-based assays, we have discovered that SNX25, a protein that targets endosomes via its PXA or PXC domain, interacts with regulator of G protein signaling (RGS) proteins (including RGS2, RGS4, RGS8, and RGS17) in a redox-regulated manner. The interaction between SNX25 and these RGS proteins enhances their GTPase-accelerating activity towards Gαi/q and their ability to bind GDP-bound (inactive form) Gαi/q. As a result, SNX25 recruits these RGS proteins to endosomes, leading to the termination of endosomal Gαi/q signaling. Furthermore, we have found that the SNX25/RGS complex also exerts a negative regulatory effect on Gαi/q signaling from the plasma membrane. This is achieved by recruiting Gαi/q to endosomes and preventing its activation on the plasma membrane. Our findings shed light on the previously unknown role of redox-modulated SNX25 in inhibiting Gαi/q signaling, thereby uncovering a novel mechanism for terminating Gαi/q signaling from endosomes. Importantly, this study expands our understanding of the regulation of GPCR-Gαi/q signaling beyond the plasma membrane.

Wound-Induced Temporal Reprogramming of Gene Expression during Agarwood Formation in Aquilaria sinensis.

Agarwood is a resinous heartwood of Aquilaria sinensis that is formed in response to mechanical wounding. However, the transcriptional response of A. sinensis to mechanical wounding during the agarwood formation process is still unclear. Here, three five-year-old A. sinensis trees were mechanically damaged by a chisel, and time-series transcriptomic analysis of xylem tissues in the treated area (TA) was performed at 15 (TA1), 70 (TA2) and 180 days after treatment (TA3). Samples from untreated areas at the corresponding time points (UA1, UA2, UA3, respectively) were collected as controls. A total of 1862 (TA1 vs. UA1), 961 (TA2 vs. UA2), 1370 (TA3 vs. UA3), 3305 (TA2 vs. TA1), 2625 (TA3 vs. TA1), 2899 (TA3 vs. TA2), 782 (UA2 vs. UA1), 4443 (UA3 vs. UA1) and 4031 (UA3 vs. UA2) genes were differentially expressed (DEGs). Functional enrichment analysis showed that DEGs were significantly enriched for secondary metabolic processes, signal transduction and transcriptional regulation processes. Most of the genes involved in lignin biosynthesis were more abundant in the TA groups, which included phenylalanine ammonia-lyase, 4-coumarate CoA ligase, cinnamate 4-hydroxylase, caffeoyl-CoA O-methyltransferase and cinnamoyl-CoA reductase. DEGs involved in sesquiterpene biosynthesis were also identified. Hydroxymethylglutaryl-CoA synthase, 3-hydroxy-3-methylglutaryl-coenzyme A reductase, phosphomevalonate kinase and terpene synthase genes were significantly increased in the TA groups, promoting sesquiterpene biosynthesis in the wounded xylem tissues. The TF-gene transcriptomic networks suggested that MYB DNA-binding, NAM, WRKY, HLH and AP2 TFs co-expressed with genes related to lignin and sesquiterpene synthesis, indicating their critical regulatory roles in the biosynthesis of these compounds. Overall, our study reveals a dynamic transcriptional response of A. sinensis to mechanical wounding, provides a resource for identifying candidate genes for molecular breeding of agarwood quality, and sheds light on the molecular mechanisms of agarwood formation in A. sinensis.

RNA-Sequencing Reveals the Involvement of Sesquiterpene Biosynthesis Genes and Transcription Factors during an Early Response to Mechanical Wounding of Aquilaria sinensis.

Plants respond to wounding by reprogramming the expression of genes involved in secondary metabolism. Aquilaria trees produce many bioactive secondary metabolites in response to wounding, but the regulatory mechanism of agarwood formation in the early response to mechanical wounding has remained unclear. To gain insights into the process of transcriptome changes and to determine the regulatory networks of Aquilaria sinensis to an early response (15 days) to mechanical wounding, we collected A. sinensis samples from the untreated (Asc1) and treated (Asf1) xylem tissues and performed RNA sequencing (RNA-seq). This generated 49,102,523 (Asc1) and 45,180,981 (Asf1) clean reads, which corresponded to 18,927 (Asc1) and 19,258 (Asf1) genes, respectively. A total of 1596 differentially expressed genes (DEGs) were detected in Asf1 vs. Asc1 (|log2 (fold change)| ≥ 1, Padj ≤ 0.05), of which 1088 were up-regulated and 508 genes were down-regulated. GO and KEGG enrichment analysis of DEGs showed that flavonoid biosynthesis, phenylpropanoid biosynthesis, and sesquiterpenoid and triterpenoid biosynthesis pathways might play important roles in wound-induced agarwood formation. Based on the transcription factor (TF)-gene regulatory network analysis, we inferred that the bHLH TF family could regulate all DEGs encoding for farnesyl diphosphate synthase, sesquiterpene synthase, and 1-deoxy-D-xylulose-5-phosphate synthase (DXS), which contribute to the biosynthesis and accumulation of agarwood sesquiterpenes. This study provides insight into the molecular mechanism regulating agarwood formation in A. sinensis, and will be helpful in selecting candidate genes for improving the yield and quality of agarwood.

Third-generation sequencing and metabolome analysis reveal candidate genes and metabolites with altered levels in albino jackfruit seedlings.

BACKGROUND: Most plants rely on photosynthesis; therefore, albinism in plants with leaves that are white instead of green causes slow growth, dwarfing, and even death. Although albinism has been characterized in annual model plants, little is known about albino trees. Jackfruit (Artocarpus heterophyllus) is an important tropical fruit tree species. To gain insight into the mechanisms underlying the differential growth and development between albino jackfruit mutants and green seedlings, we analyzed root, stem, and leaf tissues by combining PacBio single-molecule real-time (SMRT) sequencing, high-throughput RNA-sequencing (RNA-seq), and metabolomic analysis. RESULTS: We identified 8,202 differentially expressed genes (DEGs), including 225 genes encoding transcription factors (TFs), from 82,572 full-length transcripts. We also identified 298 significantly changed metabolites (SCMs) in albino A. heterophyllus seedlings from a set of 692 metabolites in A. heterophyllus seedlings. Pathway analysis revealed that these DEGs were highly enriched in metabolic pathways such as 'photosynthesis', 'carbon fixation in photosynthetic organisms', 'glycolysis/gluconeogenesis', and 'TCA cycle'. Analysis of the metabolites revealed 76 SCMs associated with metabolic pathways in the albino mutants, including L-aspartic acid, citric acid, succinic acid, and fumaric acid. We selected 225 differentially expressed TF genes, 333 differentially expressed metabolic pathway genes, and 76 SCMs to construct two correlation networks. Analysis of the TF-DEG network suggested that basic helix-loop-helix (bHLH) and MYB-related TFs regulate the expression of genes involved in carbon fixation and energy metabolism to affect light responses or photomorphogenesis and normal growth. Further analysis of the DEG-SCM correlation network and the photosynthetic carbon fixation pathway suggested that NAD-ME2 (encoding a malic enzyme) and L-aspartic acid jointly inhibit carbon fixation in the albino mutants, resulting in reduced photosynthetic efficiency and inhibited plant growth. CONCLUSIONS: Our preliminarily screening identified candidate genes and metabolites specifically affected in albino A. heterophyllus seedlings, laying the foundation for further study of the regulatory mechanism of carbon fixation during photosynthesis and energy metabolism. In addition, our findings elucidate the way genes and metabolites respond in albino trees.

[Mature-type adrenomedullin in coronary circulation immediately after reperfusion in patients with anterior acute myocardial infarction].

OBJECTIVE: Levels of adrenomedullin (AM), a potent vasodilatory peptide, have been shown to increase in the early stage of acute myocardial infarction (AMI). The purpose of this study was to determine whether coronary sinus-aortic step-up of mature forms of AM is accelerated in patients with AMI after reperfusion. METHODS: The subjects were 146 consecutive patients with a first episode of anterior AMI and 51 normal controls. All patients with AMI underwent balloon reperfusion therapy within 24 h after symptom onset. Plasma levels of two molecular forms of AM (an active, mature form [AM-m] and an intermediate, inactive glycine-extended form [AM-Gly]) in the aorta and coronary sinus (CS) were measured by specific immunoradiometric assay after reperfusion. RESULTS: Plasma levels of AM-m and AM-Gly in the aorta and CS were higher in AMI patients than in controls. CS-aortic step-up of AM-m, which is an index of myocardial production of AM-m, was significantly greater in AMI patients than in controls [(1.7 +/- 1.4) pmol/L vs (0.4 +/- 0.3) pmol/L, P < 0.01]. However, there was no significant difference in CS-aortic step-up of AM-Gly (P = 0.30). AMI patients with left ventricular dysfunction (n = 49) had a significantly higher CS-aortic AM-m step-up than AMI patients without left ventricular dysfunction (n = 97). AMm in the aorta and CS negatively correlated with the left ventricular ejection fraction (r = -0.50, r = -0.48, P < 0.01). CONCLUSION: Myocardial synthesis of AM-m is accelerated in patients with reperfused AMI, especially in patients with critical left ventricular dysfunction. Increased myocardial synthesis of active AM may protect against cardiac dysfunction, myocardial remodeling, or both after the onset of AMI.

[Polymorphic Hind III restriction site of the Y chromosome and essential hypertension in Chinese Han People].

OBJECTIVE: To examine whether there is an association essential hypertension pressure and a polymorphic Hind III biallelic marker in the non-recombining region of Y chromosome in Chinese Han people. METHODS: Peripheral blood samples were collected from 402 males with essential hypertension pressure and 455 age- and body height-matched healthy males as control group. Genomic DNA was extracted from the white blood cells. Segments of polymorphic Hind III restriction site of the Y chromosome were amplified from the genomic DNA by polymerase chain reaction (PCR). The PCR products were restricted with 10 U of Hind III overnight at 37 degrees C. The digested products were subjected to electrophoresis in 3% agarose gels, and stained with ethidium bromide. RESULTS: The Hind III (+) genotype was found in 58.5% of the men with essential hypertension (235/402), significantly lower than that in the healthy men (64.4%, 302/455, P = 0.02). The systolic blood pressure of the men with Hind III (+) genotype was 133.8 mm Hg +/- 25.2 mm Hg, significantly lower than that of the Hind III (-) genotype (138.0 mm Hg +/- 27.0 mm Hg, P < 0.05), and the diastolic blood pressure (DBP) of the men with Hind III (+) genotype was 83.5 mm Hg +/- 13.3 mm Hg, significantly lower than that of the men with Hind III (-) genotype (85.9 mm Hg +/- 14.4 mm Hg, P = 0.01), and the mean arterial pressure of the men with Hind III (+) genotype was 100.2 mm Hg +/- 16.5 mm Hg, significantly lower than that of the of the men with Hind III (+) genotype was (103.3 mm Hg +/- 17.6 mm Hg, P = 0.01). CONCLUSION: Polymorphic Hind III restriction site of the Y chromosome is associated with essential hypertension in Chinese Han people.