Phenotypic switch of vascular smooth muscle cells (VSMCs) is important in vascular remodeling which causes hyperplasia and restenosis after intimal injury. Platelets are activated at injured intima and secrete platelet-derived microvesicles (PMVs). Herein, we demonstrated the role of PMVs in VSMC phenotypic switch and the potential underlying mechanisms. In vivo, platelets were locally adhered and activated at intimal injury site, while Lamtor1 was promoted and VSMCs were dedifferentiated. PMVs, collected from collagen-activated platelets in vitro which mimicked collagen exposure during intimal injury, promoted VSMC dedifferentiation, induced Lamtor1 expression, and activated mTORC1 signaling, reflected by the phosphorylation of two downstream targets, i.e., S6K and 4E-BP1. Knockdown of Lamtor1 with small interfering RNA attenuated these processes induced by PMVs. Based on the previously published proteomic data, Ingenuity Pathway Analysis revealed that Src may participate in regulating effects of PMVs. Src inhibitor significantly reversed the effects of PMVs on VSMC dedifferentiation, Lamtor1 expression and mTORC1 activation. Furthermore, in SMC-specific Lamtor1 knockout mice, intimal hyperplasia was markedly attenuated after intimal injury compared with the wild type. Our data suggested that PMVs secreted by activated platelets promoted VSMC dedifferentiation via Src/Lamtor1/mTORC1 signaling pathway. Lamtor1 may be a potential therapeutic target for intimal hyperplasia after injury.

The arterial mechanical microenvironment, including stiffness, is a crucial pathophysiological feature of vascular remodeling, such as neointimal hyperplasia after carotid endarterectomy and balloon dilatation surgeries. In this study, we examined changes in neointimal stiffness in a Sprague-Dawley rat carotid artery intimal injury model and revealed that extracellular matrix (ECM) secretion and vascular stiffness were increased. Once the endothelial layer is damaged in vivo, activated platelets adhere to the intima and may secrete platelet-derived extracellular vesicles (pEVs) and communicate with vascular smooth muscle cells (VSMCs). In vitro, pEVs stimulated VSMCs to promote collagen secretion and cell adhesion. MRNA sequencing analysis of a carotid artery intimal injury model showed that ECM factors, including col8a1, col8a2, col12a1, and elastin, were upregulated. Subsequently, ingenuity pathway analysis (IPA) was used to examine the possible signaling pathways involved in the formation of ECM, of which the Akt pathway played a central role. In vitro, pEVs activated Akt signaling through the PIP3 pathway and induced the production of Col8a1. MicroRNA (miR) sequencing of pEVs released from activated platelets revealed that 14 of the top 30 miRs in pEVs targeted PTEN, which could promote the activation of the Akt pathway. Further research showed that the most abundant miR targeting PTEN was miR-92a-3p, which promoted Col8a1 expression. Interestingly, knockdown of Col8a1 expression in vivo abrogated the increase in carotid artery stiffness and simultaneously increased the degree of neointimal hyperplasia. Our results revealed that pEVs may deliver miR-92a-3p to VSMCs to induce the production and secretion of Col8a1 via the PTEN/PIP3/Akt pathway, subsequently increasing vascular stiffness. Therefore, pEVs and key molecules may be potential therapeutic targets for treating neointimal hyperplasia.

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Background Sugarcane is the most important sugar crop, contributing > 80% of global sugar production. High sucrose content is a key target of sugarcane breeding, yet sucrose improvement in sugarcane remains extremely slow for decades. Molecular breeding has the potential to break through the genetic bottleneck of sucrose improvement. Dissecting the molecular mechanism(s) and identifying the key genetic elements controlling sucrose accumulation will accelerate sucrose improvement by molecular breeding. In our previous work, a proteomics dataset based on 12 independent samples from high- and low-sugar genotypes treated with ethephon or water was established. However, in that study, employing conventional analysis, only 25 proteins involved in sugar metabolism were identified . Results In this work, the proteomics dataset used in our previous study was reanalyzed by three different statistical approaches, which include a logistic marginal regression, a penalized multiple logistic regression named Elastic net, as well as a Bayesian multiple logistic regression method named Stochastic search variable selection (SSVS) to identify more sugar metabolism-associated proteins. A total of 507 differentially abundant proteins (DAPs) were identified from this dataset, with 5 of them were validated by western blot. Among the DAPs, 49 proteins were found to participate in sugar metabolism-related processes including photosynthesis, carbon fixation as well as carbon, amino sugar, nucleotide sugar, starch and sucrose metabolism. Based on our studies, a putative network of key proteins regulating sucrose accumulation in sugarcane is proposed, with glucose-6-phosphate isomerase, 2-phospho-D-glycerate hydrolyase, malate dehydrogenase and phospho-glycerate kinase, as hub proteins. Conclusions The sugar metabolism-related proteins identified in this work are potential candidates for sucrose improvement by molecular breeding. Further, this work provides an alternative solution for omics data processing.

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