Deleting the BAFF receptor TACI protects against systemic lupus erythematosus without extensive reduction of B cell numbers

B cell-activating factor of the TNF family (BAFF) is an essential B cell survival factor. However, high levels of BAFF promote systemic lupus erythematosus (SLE) in mice and humans. Belimumab (anti-human BAFF) limits B cell survival and is approved for use in patients with SLE. Surprisingly, the efficacy of rituximab (anti-human CD20) in SLE remains controversial, despite depleting B cells more potently than belimumab. This raises the question of whether B cell depletion is really the mechanism of action of belimumab. In BAFF transgenic mice, SLE development is T cell-independent but relies on innate activation of B cells via TLRs, and TLR expression is modulated by the BAFF receptor TACI. Here, we show that loss of TACI on B cells protected against BAFF-mediated autoimmune manifestations while preserving B cells, suggesting that loss of BAFF signaling through TACI rather than loss of B cells may underpin the effect of belimumab in the clinic. Therefore, B cell-sparing blockade of TACI may offer a more specific and safer therapeutic alternative to broad B cell depletion in SLE.     

NO调节在小鼠生发泡期卵母细胞体外成熟中的作用

目的观察不同浓度硝普钠(SNP)、左旋硝基精氨酸甲基酯(L-NAME)对小鼠生发泡(GV)期卵母细胞体外成熟的影响。方法给小鼠腹腔注射PMSG 8IU,取其双侧卵巢,用卵母细胞体外培养法,分为L-NAME组、SNP+dbc AMP+L-NAME组、P+dbc AMP+SNP+L-NAME组,在倒置生物显微镜下观察卵母细胞生发泡破裂(GVBD)率及第一极体(PB1)排出率。结果 SNP+dbc AMP组的GVBD率与PB1率分别为(52.5±0.4与32.5±0.1)显著高于dbc AMP组的(28.0±0.2与11.1±0.7)(P0.05)。P+dbc AMP+SNP+L-NAME组的GVBD率与PB1率分别为(62.8±0.3与20±1.4)显著低于P+dbc AMP+SNP组的(90.1±1.3与66.6±0.9),GVBD率与PB1率显著性降低(P0.05)。结论 L-NAME与二丁酰环腺苷酸(dbc AMP)抑制小鼠卵母细胞成熟时,小剂量NO呈现促进作用,这种促进作用在孕酮(P)存在时进一步加强。     

A unique C2 domain at the C terminus of Munc13 promotes synaptic vesicle priming

Neurotransmitter release during synaptic transmission comprises a tightly orchestrated sequence of molecular events, and Munc13-1 is a cornerstone of the fusion machinery. A forward genetic screen for defects in neurotransmitter release in Caenorhabditis elegans identified a mutation in the Munc13-1 ortholog UNC-13 that eliminated its unique and deeply conserved C-terminal module (referred to as HC2M) containing a Ca²⁺-insensitive C2 domain flanked by membrane-binding helices. The HC2M module could be functionally replaced in vivo by protein domains that localize to synaptic vesicles but not to the plasma membrane. HC2M is broadly conserved in other Unc13 family members and is required for efficient synaptic vesicle priming. We propose that the HC2M domain evolved as a vesicle/endosome adaptor and acquired synaptic vesicle specificity in the Unc13ABC protein family.

Chemical synaptic transmission is the primary mode of cellular communication within the nervous system. The presynaptic piece of this process encompasses a remarkable set of sequential and highly regulated interactions between a host of proteins, synaptic vesicles (SV), the plasma membrane, and calcium ions (Ca²⁺). Fusion of neurotransmitter-containing vesicles with the presynaptic plasma membrane is driven by the assembly of the neuronal SNAREs SNAP-25 and Syntaxin 1 on the plasma membrane and Synaptobrevin-2/VAMP2 on the SV. The assembly process and its coupling to intracellular Ca²⁺ are choreographed by a deeply conserved group of proteins including Munc13, Munc18, Synaptotagmin 1, and Complexin (1–4). Together with the SNAREs, these proteins form the core of the fusion apparatus across all metazoan nervous systems (5–7).First identified in a landmark genetic screen for nervous system mutants in the nematode Caenorhabditis elegans, UNC-13 is the founding member of the highly conserved metazoan Unc13 secretory protein family that includes Unc13ABC in humans (Munc13-1/2/3 in mice) (8–10). Munc13-1/UNC-13 localizes to the presynaptic active zone and is implicated in numerous presynaptic functions including initiation of release site assembly, SV docking and priming, Ca²⁺- and lipid-dependent forms of short-term synaptic plasticity, opening and positioning Syntaxin 1 for SNARE assembly, and protecting SNARE complexes from disassembly by NSF/alpha-SNAP (3, 11–13). Loss of Munc13-1 orthologs in the nervous system almost entirely eliminates all forms of chemical synaptic transmission, establishing the Unc13 family as essential to this process (14–16). All UNC-13 orthologs contain a large Syntaxin-binding MUN domain flanked by a Ca²⁺- and lipid-binding C1-C2 module and an additional C2 domain on its C terminus referred to as C2C (5, 10, 17).The C-terminal end of UNC-13 is the least understood domain within the Unc13 protein family in terms of both structure and mechanism (18, 19). Recent work on the MUN and C2C domains of Munc13-1 both in vitro and in cultured hippocampal synapses supports the notion that the MUN-C2C region attaches Munc13-1 to SVs as a means of preparing SVs for fusion (20, 21), but several questions remain unresolved. Is the SV interaction mediated by direct membrane binding? Does the C2C domain itself bind to SVs or does the MUN domain serve this role? Does either domain provide cargo specificity as part of the priming process? Interestingly, the C-terminal end of the MUN domain of CAPS, another Unc13 family member, can bind dense-core vesicles (DCVs) although it lacks a C-terminal C2 domain (22). Moreover, the MUN domain without the C2C domain has also been demonstrated to bind liposomes through an interaction with Synaptobrevin 2 (23). These observations bring up several possibilities for interactions with the C terminus of Munc13 including direct MUN–membrane interactions, C2C–membrane interactions, or protein–protein interactions involving either or both domains. Other Unc13 family members possessing a MUN domain with a C-terminal C2 domain such as Unc13D/Munc13-4 and BAIAP3 have been proposed to tether specific cargo such as endosomes, secretory granules, and large DCVs (24, 25). How Unc13 proteins select among different cargos remains largely unanswered (24, 26, 27).Through behavioral, electrophysiological, biochemical, and genetic approaches, we uncover a deeply conserved C-terminal membrane-binding domain within Munc13-1/UNC-13 termed the Munc13 C-terminal (MCT) domain. This region, together with C2C and a neighboring N-terminal helix fold together into a stable membrane-binding protein domain in vitro, and loss of any part of this module in vivo impairs SV priming and nervous system function. Moreover, the C-terminal domain can be replaced by foreign domains that bind SVs but not the plasma membrane, demonstrating a role in SV interactions at the synapse. Phylogenetic protein sequence comparisons suggest that the ancestral Unc13/BAIAP3 homolog possessed a similar C-terminal domain prior to the emergence of metazoa, and subsequently, the UNC-13ABC subfamily domain evolved as an SV adaptor that plays a critical role in neurotransmission in all animals.     

Hypoxic Lung-Cancer-Derived Extracellular Vesicle MicroRNA-103a Increases the Oncogenic Effects of Macrophages by Targeting PTEN

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左卡尼汀对玻璃化冷冻小鼠卵母细胞体外受精结局的影响

目的：研究左卡尼汀对玻璃化冷冻小鼠卵母细胞的影响。方法：将卵母细胞分为新鲜组（存活卵数243个）,玻璃化冷冻组（解冻卵数282个）,左卡尼汀高、中、低剂量（2．0、1．0、0．5 g／L）组（解冻卵数分别为285、280和279个）。观察各组卵母细胞中GSH含量、ROS水平以及卵母细胞存活率、受精率、卵裂率、囊胚形成率。结果：5组卵母细胞GSH含量、ROS 水平及卵母细胞存活率、受精率、卵裂率、囊胚形成率差异均有统计学意义（ F ＝881．290、182．760及χ2＝113．361、21．560、16．660、9．667,P均＜0．05）。与新鲜卵母细胞比较,玻璃化冷冻卵母细胞中GSH含量降低,ROS水平升高,卵母细胞存活率、受精率、卵裂率均降低（ P＜0．05）。左卡尼汀呈剂量依赖性地增加玻璃化冷冻卵母细胞中GSH含量,降低ROS水平（P＜0．05）;高剂量左卡尼汀可明显改善玻璃化冷冻卵母细胞的存活率（ P＜0．05）。结论：左卡尼汀可通过抗氧化作用改善玻璃化冷冻卵母细胞的结局。     

Identification and functional analysis of a novel chorion protein essential for egg maturation in the brown planthopper

In insect eggs, the chorion has the essential function of protecting the embryo from external agents during development while allowing gas exchange for respiration. In this study, we found a novel gene, Nilaparvata lugens chorion protein (NlChP), that is involved in chorion formation in the brown planthopper, Nilaparvata lugens. NlChP was highly expressed in the follicular cells of female adult brown planthoppers. Knockdown of NlChP resulted in oocyte malformation and the inability to perform oviposition, and electron microscopy showed that the malformed oocytes had thin and rough endochorion layers compared to the control group. Liquid chromatography with tandem mass spectrometry analysis of the eggshell components revealed four unique peptides that were matched to NlChP. Our results demonstrate that NlChP is a novel chorion protein essential for egg maturation in N. lugens, a hemipteran insect with telotrophic meroistic ovaries. NlChP may be a potential target in RNA interference‐based insect pest management.     

Germinal center B (GCB) and non-GCB cell-like diffuse large B cell lymphomas have similar outcomes following autologous haematopoietic stem cell transplantation

Patients with germinal center B cell-like (GCB) and non-GCB diffuse large B cell lymphomas (DLBCL) receiving first line therapy have distinct prognosis. We explored the differences in outcome following salvage autologous hematopoietic stem cell (HSC) transplantation between patients with GCB and non-GCB DLBCL. Forty-four patients with relapsed and 15 patients with primary refractory chemosensitive disease undergoing BEAM (BCNU [carmustine], etoposide, cytarabine, melphalan) conditioning and autologous HSC were included. Immunohistochemical analysis was performed for CD10, BCL-6, MUM1 (allowing classification into GCB and non-GCB-like DLBCL) and BCL-2. Median follow-up of survivors was 25 months; median age at the time of transplantation was 60 years (range 17–77). Thirty-two patients (54%) were classified as having GCB and 27 (46%) as having non-GCB-like DLBCL. Patients with GCB and non-GCB DLBCL did not differ in the risk of progression after HSC transplant ( P  = 0·78) or overall survival ( P  = 0·48). In multivariate analysis, only time to progression after initial treatment impacted overall survival. We conclude that patients with relapsed or primary refractory chemosensitive GCB and non-GCB-like DLBCL derive similar benefit from autologous HSC transplant.     

Distribution and morphology of sensory and autonomic fibres in the subendocardial plexus of the rat heart

Cardiac reflexes originating from sensory receptors in the heart ensure blood supply to vital tissues and organs in the face of constantly changing demands. Atrial volume receptors are mechanically sensitive vagal afferents which relay to the medulla and hypothalamus, affecting vasopressin release and renal sympathetic activity. To date, two anatomically distinct sensory endings have been identified which may subserve cardiac mechanosensation: end-nets and flower-spray endings. To map the distribution of atrial receptors in the subendocardial space, we have double-labelled rat right atrial whole mounts for neurofilament heavy chain (NFH) and synaptic vesicle protein 2 (SV2) and generated high-resolution maps of the rat subendocardial neural plexus at the cavo-atrial region. In order to elucidate the nature of these fibres, double labelling with synaptophysin (SYN) and either NFH, calcitonin gene-related peptide (CGRP), choline acetyltransferase (ChAT) or tyrosine hydroxylase (TH) was performed. The findings show that subendocardial nerve nets are denser at the superior cavo-atrial junction than the mid-atrial region. Adluminal plexuses had the finest diameters and stained positively for synaptic vesicles (SV2 and SYN), CGRP and TH. These plexuses may represent sympathetic post-ganglionic fibres and/or sensory afferents. The latter are candidate substrates for type B volume receptors which are excited by stretch during atrial filling. Deeper nerve fibres appeared coarser and may be cholinergic (positive staining for ChAT). Flower-spray endings were never observed using immunohistochemistry but were delineated clearly with the intravital stain methylene blue. We suggest that differing nerve fibre structures form the basis by which atrial deformation and hence atrial filling is reflected to the brain.     

Heterogeneity of germinal center B cells: New insights from single-cell studies

Upon antigen exposure, activated B cells in antigen-draining lymphoid organs form microanatomical structures, called germinal centers (GCs), where affinity maturation occurs. Within the GC microenvironment, GC B cells undergo proliferation and B cell receptor (BCR) genes somatic hypermutation in the dark zone (DZ), and affinity-based selection in the light zone (LZ). In the current paradigm of GC dynamics, high-affinity LZ B cells may be selected by cognate T- follicular helper cells to either differentiate into plasma cells or memory B cells, or re-enter the DZ and initiate a new round of proliferation and BCR diversification, before migrating back to the LZ. Given the diversity of cell states and potential cell fates that GC B cells may adopt, the two-state DZ-LZ paradigm has been challenged by studies that explored GC B-cell heterogeneity with a variety of single-cell technologies. Here, we review studies and single-cell technologies which have allowed to refine the working model of GC B-cell cellular and molecular heterogeneity during affinity maturation. This review also covers the use of single-cell quantitative data for mathematical modeling of GC reactions, and the application of single-cell genomics to the study of GC-derived malignancies.     

Mutation analysis of tubulin beta 8 class VIII in infertile females with oocyte or embryonic defects

Variants of tubulin beta 8 class VIII (TUBB8) have been shown to be associated with female infertility characterized by oocyte or embryonic defects. To further investigate the mutational spectrum of TUBB8 and the prevalence of variants, we performed Sanger sequencing of TUBB8 on a total of 115 infertile females who had undergone repeated in vitro fertilization cycles with oocyte or embryonic defects and 200 healthy controls. A total of 31 variants which were absent from the controls were identified in 36 unrelated individuals, accounting for a large proportion of this cohort (31.3%). All of the variants including heterozygous/homozygous missense variants and a heterozygous frameshift insertion variant were at conserved sites and predicted to be deleterious. Besides, these variants had diverse phenotypic effects, including not only oocyte maturation arrest, fertilization failure, and early embryonic arrest, but also multi‐pronuclei (MPN) formation, which is a new phenotype associated with TUBB8 variants. Overall, this study reveals a large number of variants of the TUBB8 gene in infertile females with oocyte or embryonic defects. Our results not only broaden the mutational and phenotypic spectra of TUBB8 variants, but also further confirm the critical role of TUBB8 in oocyte maturation, fertilization, and early embryonic development.