BMP2/7 heterodimer enhances osteogenic differentiation of rat BMSCs via ERK signaling compared with respective homodimers

Bone morphogenetic protein (BMP)2/7 heterodimer shows greater efficacy in enhancing bone regeneration. However, the precise mechanism and the role of mitogen-activated protein kinase (MAPK) signaling network in BMP2/7-driven osteogenesis remain ambiguous. In this study, we evaluated the effects of BMP2/7 heterodimers on osteoblastic differentiation in rat bone marrow mesenchymal stem cells (BMSCs), with the aim to elaborate how MAPKs might be involved in this cellular process by treatment of rat BMSCs with BMP2/-7 with a special signal-pathway inhibitor. We found that BMP2/7 heterodimer induced a much stronger osteogenic response in rat BMSCs compared with either homodimer. Most interestingly, extracellular signal-regulated kinase (ERK) demonstrated a highly sustained phosphorylation and activation in the BMP2/7 heterodimer treatment groups, and inhibition of ERK cascades using U0126 special inhibitor that significantly reduced the activity of ALP and calcium mineralization to a substantial degree in rat BMSCs treated with BMP2/7 heterodimers. Collectively, we demonstrate that BMP2/7 heterodimer shows a potent ability to stimulate osteogenesis in rat BMSCs. The activated ERK signaling pathway involved in this process may contribute partially to an increased osteogenic potency of heterodimeric BMP2/7 growth factors.     

Lentiviral-mediated silencing of mast cell-expressed membrane protein 1 promotes angiogenesis of rats with cerebral ischemic stroke

Cerebral ischemic stroke is a devastating neurological disease with high rates of morbidity, disability, and mortality. Lentiviral-mediated mast cell-expressed membrane protein 1 (MCEMP1) has been shown to function in ischemic stroke. Hence, this study aims to explore the function of MCEMP1 specifically in angiogenesis, neuronal proliferation, and apoptosis in rats with cerebral ischemic stroke. Initially, stroke-related genes were obtained through microarray-based gene expression analysis, followed by the construction of a lentiviral vector for MCEMP1 shRNA and establishment of the middle cerebral artery occlusion model. After rats were transfected with MCEMP1 shRNA lentivirus, microvessel density (MVD), expression of MCEMP1, caspase-3, and vascular endothelial growth factor (VEGF), and neuronal proliferation and apoptosis were measured to explore the role of MCEMP1 in cerebral ischemic stroke. MCEMP1 was found to be highly expressed in rats with cerebral ischemic stroke. Silencing of MCEMP1 led to upregulation of VEGF, while downregulation of caspase-3, and resulted in the promotion of MVD in rats with ischemic stroke. Moreover, MCEMP1 silencing could increase Ki67 positive cells and reduce terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling positive cells in the marginal zone of cortical infarction in rats. Our study provides evidence that silenced MCEMP1 could enhance angiogenesis and suppress neuronal apoptosis in rats with cerebral ischemic stroke, highlighting that MCEMP1 silencing could serve as a therapeutic target for cerebral ischemic stroke treatment.     

Tomato stigma exsertion induced by high temperature is associated with the jasmonate signalling pathway

High temperature (HT) is becoming an increasingly serious factor in limiting crop production with global climate change. During hot seasons, owing to prevailing HT, cultivated tomatoes are prone to exhibiting stigma exsertion, which hampers pollination and causes fruit set failure. However, the underlying regulatory mechanisms of the HT‐induced stigma exsertion remain largely unknown. Here, we demonstrate that stigma exsertion induced by HT in cultivated tomato is caused by more seriously shortened stamens than pistils, which is different from the stigma exsertion observed in wild tomato species. Under the HT condition, the different responses of pectin, sugar, expansin, and cyclin cause cell wall remodelling and differentially localized cell division and selective cell enlargement, which further determine the lengths of stamens and pistils. In addition, auxin and jasmonate (JA) are implicated in regulating cell division and cell expansion in stamens and pistils, and exogenous JA instead of auxin treatment can effectively rescue tomato stigma exsertion through regulating the JA/COI1 signalling pathway. Our findings provide a better understanding of stigma exsertions under the HT condition in tomato and uncover a new function of JA in improving plant abiotic stress tolerance.     

Arabidopsis HSP70‐16 is required for flower opening under normal or mild heat stress temperatures

Sepals play important roles in protecting inner floral organs from various stresses and in guaranteeing timely flower opening. However, the exact role of sepals in coordinating interior and exterior signals remains elusive. In this study, we functionally characterized a heat shock protein gene, Arabidopsis HSP70‐16, in flower opening and mild heat stress response, using combined genetics with anatomic, physiological, chemical, and molecular analyses. We showed that HSP70‐16 is required for flower opening and mild heat response. Mutation of HSP70‐16 led to a significant reduction in seed setting rate under 22°C, which was more severe at 27°C. Mutation of HSP70‐16 also caused postgenital fusion at overlapping tips of two lateral sepals, leading to failed flower opening, abnormal floral organ formation, and impaired fertilization and seed setting. Chemical and anatomic analyses confirmed specific chemical and morphological changes of cuticle property in mutant lateral sepals, and qRT‐PCR data indicated that expression levels of different sets of cuticle regulatory and biosynthetic genes were altered in mutants grown at both 22°C and 27°C temperatures. This study provides a link between thermal and developmental perception signals and expands the understanding of the roles of sepal in plant development and heat response.     

Calculation of an Adequate Intake (AI) Value and Safe Range of Selenium (Se) for Chinese Infants 0–3 Months Old Based on Se Concentration in the Milk of Lactating Chinese Women with Optimal Se Intake

Biological Trace Element Research - The required selenium intake for optimal health in Chinese residents was published in 2014. However, the adequate intake (AI) value for Chinese infants...