Lectin receptor kinase OsLecRK‐S.7 is required for pollen development and male fertility

Pollen grains are covered by exine that protects the pollen from stress and facilitates pollination. Here we isolated a male sterile mutant s13283 in rice exhibiting aborted pollen with abnormal exine and defective aperture. The mutant gene encodes a novel plasma membrane‐localized legume‐lectin receptor kinase that we named OsLecRK‐S.7. OsLecRK‐S.7 was expressed at different levels in all tested tissues and throughout anther development. In vitro kinase assay showed OsLecRK‐S.7 capable of autophosporylation. Mutation in s13283 (E560K) and mutation of the conserved ATP binding site (K418E) both knocked out the kinase activity. Mass spectrometry showed Thr₃₇₆, Ser₃₇₈, Thr₃₈₆, Thr₄₀₃, and Thr₆₅₇ to be the autophosphorylation sites. Mutation of individual autophosphorylation site affected the in vitro kinase activity to different degrees, but did not abolish the gene function in fertility complementation. oslecrk‐s.7 mutant plant overexpressing OsLecRK‐S.7 recovered male fertility but showed severe growth retardation with reduced number of tillers, and these phenotypes were abolished by E560K or K418E mutation. The results indicated that OsLecRK‐S.7 was a key regulator of pollen development.     

植物凝集素类受体蛋白激酶研究进展

自然界中植物的生长发育受到各种环境变化的影响。为了响应外界各种环境条件,植物演化出一系列识别和传递环境信号的蛋白分子,其中比较典型的是植物细胞质膜上的类受体蛋白激酶(RLKs)。凝集素类受体蛋白激酶(LecRLKs)是类受体蛋白激酶家族中的一个亚族,它主要包含3个结构域:细胞外凝集素结构域、跨膜结构域和细胞内激酶结构域。根据细胞外凝集素结构域的不同,LecRLKs可分为3种不同类型:L、G和C型。近年来,研究表明LecRLKs在植物生物/非生物胁迫和发育调控中发挥非常重要的作用。该文综述了植物凝集素类受体蛋白激酶的研究历史、结构特点、分类以及生物学功能,并重点阐述凝集素类受体蛋白激酶在植物生物/非生物胁迫响应和调控发育方面的功能。对不同类型和不同功能的植物凝集素类受体蛋白激酶进行阐述将有利于对该类蛋白开展功能研究,并为作物改良提供有益借鉴。     

Genes involved in the immediate early response and epithelial-mesenchymal transition are regulated by adipocytokines in the female reproductive tract

Obesity increases the risk of female reproductive tract cancers, but the underlying mechanistic link between the two is ill‐defined. Thus, the objective of the current study was to identify obesity‐dependent changes in the expression of immediate early (IE) genes that contribute to cell proliferation and differentiation, and epithelial–mesenchymal transition (EMT) genes that promote cell migration. When HeLa cells were treated for 0–48 hr with IGF‐1, leptin, TNFα, or IL‐6, each individual adipocytokine altered the abundance of IE (cJUN, cFOS, and cMYC) and EMT (SNAI1, SNAI2, and TWIST1) mRNA abundance. For example, IGF‐1 increased cJUN and cFOS and decreased cMYC; leptin increased cFOS; IL‐6 increased cFOS and cMYC; and TNFα increased cJUN and cFOS mRNA abundance. Likewise, EMT gene expression was altered by IGF‐1, TNFα, and IL‐6. SNAI1 was increased by IGF‐1 and IL‐6; SNAI2 was increased by IGF‐1 and TNFα; and TWIST1 was increased by TNFα and IL‐6. Chronic exposure to adipocytokines also altered EMT gene expression in the whole uterus of obese compared to normal‐weight mice. Specifically, there was no difference in cJun, cFos, or cMyc mRNA abundance between normal‐weight and obese animals. Snai1, Snai2, and Twist1 mRNA abundance, however, was increased in the uterus of obese females and correlated with increased circulating IGF‐1 levels. These data indicate that obesity‐dependent alterations in adipocytokine levels regulate the expression of genes associated with cell proliferation and migration, and therefore may provide a plausible mechanism for obesity‐dependent increases in cancers of the female reproductive tract. Mol. Reprod. Dev. 79:128–137, 2012. © 2011 Wiley Periodicals, Inc.     

CRISPR-mediated host genomic DNA damage is efficiently repaired through microhomology-mediated end joining in Zymomonas mobilis

CRISPR-Cas systems provide bacteria and archaea with adaptive immunity against mobile genetic elements(MGEs) through uptake of invader-derived spacers. De novo adaptation samples spacers from both invaders and hosts, whereas primed adaptation shows higher specificity to sample spacers from invaders in many model systems as well as in the subtype I-F system of Zymomonas mobilis. Self-derived spacers will lead to CRISPR self-interference. However, our in vivo study demonstrated that this species used the microhomology-mediated end joining(MMEJ) pathway to efficiently repair subtype I-F CRISPR-Cas system-mediated DNA breaks guided by the self-targeting spacers. MMEJ repair of DNA breaks requires direct microhomologous sequences flanking the protospacers and leads to DNA deletions covering the protospacers. Importantly, CRISPR-mediated genomic DNA breaks failed to be repaired via MMEJ pathway in presence of higher copies of short homologous DNA. Moreover, CRISPR-cleaved exogenous plasmid DNA was failed to be repaired through MMEJ pathway, probably due to the inhibition of MMEJ by the presence of higher copies of the plasmid DNA in Z. mobilis. Our results infer that MMEJ pathway discriminates DNA damages between in the host chromosome versus mobile genetic element(MGE) DNA, and maintains genome stability post CRISPR immunity in Z. mobilis.     

GDSL esterase/lipases OsGELP34 and OsGELP110/OsGELP115 are essential for rice pollen development

Pollen exine contains complex biopolymers of aliphatic lipids and phenolics. Abnormal development of pollen exine often leads to plant sterility. Molecular mechanisms regulating exine formation have been studied extensively but remain ambiguous. Here we report the analyses of three GDSL esterase/lipase protein genes, OsGELP34, OsGELP110, and OsGELP115, for rice exine formation. OsGELP34 was identified by cloning of a male sterile mutant gene. OsGELP34 encodes an endoplasmic reticulum protein and was mainly expressed in anthers during pollen exine formation. osgelp34 mutant displayed abnormal exine and altered expression of a number of key genes required for pollen development. OsGELP110 was previously identified as a gene differentially expressed in meiotic anthers. OsGELP110 was most homologous to OsGELP115, and the two genes showed similar gene expression patterns. Both OsGELP110 and OsGELP115 proteins were localized in peroxisomes. Individual knockout of OsGELP110 and OsGELP115 did not affect the plant fertility, but double knockout of both genes altered the exine structure and rendered the plant male sterile. OsGELP34 is distant from OsGELP110 and OsGELP115 in sequence, and osgelp34 and osgelp110/osgelp115 mutants were different in anther morphology despite both were male sterile. These results suggested that OsGELP34 and OsGELP110/OsGELP115 catalyze different compounds for pollen exine development.     

Nel positively regulates the genesis of retinal ganglion cells by promoting their differentiation and survival during development

For correct functioning of the nervous system, the appropriate number and complement of neuronal cell types must be produced during development. However, the molecular mechanisms that regulate the production of individual classes of neurons are poorly understood. In this study, we investigate the function of the thrombospondin-1–like glycoprotein, Nel (neural epidermal growth factor [EGF]-like), in the generation of retinal ganglion cells (RGCs) in chicks. During eye development, Nel is strongly expressed in the presumptive retinal pigment epithelium and RGCs. Nel overexpression in the developing retina by in ovo electroporation increases the number of RGCs, whereas the number of displaced amacrine cells decreases. Conversely, knockdown of Nel expression by transposon-mediated introduction of RNA interference constructs results in decrease in RGC number and increase in the number of displaced amacrine cells. Modifications of Nel expression levels do not appear to affect proliferation of retinal progenitor cells, but they significantly alter the progression rate of RGC differentiation from the central retina to the periphery. Furthermore, Nel protects RGCs from apoptosis during retinal development. These results indicate that Nel positively regulates RGC production by promoting their differentiation and survival during development.     

马桑内酯对培养的大鼠海马星形胶质细胞的激活

实验研究了马桑内酯对纯化培养的大鼠海马星形胶质细胞的影响。发现：（1）免疫细胞化学染色证实马桑内酯作用2h可引起胶质细胞核内NF-кBp65的表达,8h达高峰,至24hNF-кBp65阳性胞核的百分率和平均光密度仍维持在高水平;预先用PDTC作用1h可完全抑制NF-кBp65的核表达,而TNFα单抗则可延迟NF-кBp65免疫反应阳性胞核出现的时间,阳性胞核百分率及其平均光密度也有所下降;（2）酶联免疫吸附实验发现马桑内酯可促进星形胶质细胞培养基内TNFα含量升高,PDTC可部分对抗此作用,本实验表明马桑内酯激活星形胶质细胞的作用部分是由TNFα介导的。