Exploring Sonic Hedgehog Cell Signaling in Neurogenesis: Its Potential Role in Depressive Behavior

Neurochemical Research - Depression is the most prevalent form of neuropsychiatric disorder affecting all age groups globally. As per the estimation of the World Health Organization (WHO),...     

Regulatory Role of Zinc in Immune Cell Signaling

Zinc is an essential micronutrient with crucial roles in multiple facets of biological processes. Dysregulated zinc homeostasis impairs overall immune function and resultantly increases susceptibility to infection. Clinically, zinc supplementation is practiced for treatment of several infectious diseases, such as diarrhea and malaria. Recent focus on zinc as a beneficial element for immune system support has resulted in investigation of the immunomodulatory roles of zinc in a variety of immune cells. Besides its classical role as a cofactor that regulates the structural function of thousands of proteins, accumulating evidence suggests that zinc also acts, in a manner similar to calcium, as an ionic regulator of immune responses via participation as an intracellular messenger in signaling pathways. In this review, we focus on the role of zinc as a signaling molecule in major pathways such as those downstream of Toll-like receptors-, T cell receptor-, and cytokine-mediated signal transduction that regulate the activity and function of monocytes/macrophages and T cells, principal players in the innate and adaptive immune systems.     

Multiple Roles of Canonical Wnt Signaling in Cell Cycle Progression and Cell Lineage Specification in Neural Development

Signaling by the canonical Wnt pathway has multiple functions in stem cells. It caneither control stem cell expansion or –as we have recently demonstrated withneural crest stem cells– influence cell lineage decisions by promoting specific fatesat the expense of others. Thus, the role of canonical Wnt in stem cells is dependenton cell-intrinsic properties that determine how a cell responds to Wnt. Themolecular basis for the functional diversity of Wnt in different stem cell typesremains to be elucidated.     

Computational Prediction of Amino Acids Governing Protein-Membrane Interaction for the PIP3 Cell Signaling System

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Localization of a Rho GTPase Implies a Role in Tip Growth and Movement of the Generative Cell in Pollen Tubes

The Rho family GTPases function as key molecular switches, controlling a variety of actin-dependent cellular processes, such as the establishment of cell polarity, cell morphogenesis, and movement in diverse eukaryotic organisms. A novel subfamily of Rho GTPases, Rop, has been identified in plants. Protein gel blot and RNA gel blot hybridization analyses indicated that one of these plant Rho GTPases, Rop1, is expressed predominantly in the male gametophyte (pollen and pollen tubes). Cell fractionation analysis of pollen tubes showed that Rop is partitioned into soluble and particulate fractions. The particulate Rop could be solubilized with detergents but not with salts, indicating that it is tightly bound to membranes. The membrane association appears to result from membrane anchoring via a geranylgeranyl group because an in vitro isoprenylation assay demonstrated that Rop1Ps is geranylgeranylated. Subcellular localization, using indirect immunofluorescence and confocal microscopy, showed that Rop is highly concentrated in the cortical region of the tube apex and in the periphery of the generative cell. The cortical Rop protein at the apex forms a gradient with decreasing concentration from tip to base and appears to be associated with the plasma membrane. These results suggest that the apical Rop GTPase may be involved in the signaling mechanism that controls the actin-dependent tip growth of pollen tubes. Localization of the Rop GTPase to the periphery of the generative cell is analogous to that of myosin, suggesting that the Rop GTPase plays an important role in the modulation of an actomyosin motor system involved in the movement of the generative cell.     

The Role of GRASP65 in Golgi Cisternal Stacking and Cell Cycle Progression

In vitro assays identified the Golgi peripheral protein GRASP65 as a Golgi stacking factor that links adjacent Golgi cisternae by forming mitotically regulated trans‐oligomers. These conclusions, however, require further confirmation in the cell. In this study, we showed that the first 112 amino acids at the N‐terminus (including the first PDZ domain, PDZ1) of the protein are sufficient for oligomerization. Systematic electron microscopic analysis showed that the expression of non‐regulatable GRASP65 mutants in HeLa cells enhanced Golgi stacking in interphase and inhibited Golgi fragmentation during mitosis. Depletion of GRASP65 by small interference RNA (siRNA) reduced the number of cisternae in the Golgi stacks; this reduction was rescued by expressing exogenous GRASP65. These results provided evidence and a molecular mechanism by which GRASP65 stacks Golgi cisternal membranes. Further experiments revealed that inhibition of mitotic Golgi disassembly by expressing non‐regulatable GRASP65 mutants did not affect equal partitioning of the Golgi membranes into the daughter cells. However, it delayed mitotic entry and suppressed cell growth; this effect was diminished by dispersing the Golgi apparatus with Brefeldin A treatment prior to mitosis, suggesting that Golgi disassembly at the onset of mitosis plays a role in cell cycle progression.     

Notch信号及其对T细胞发育和分化的调节

哺乳动物Notch蛋白包括四种(Notchl～Notch4),其配体分为两个家族:Jagged家族(Jaggedl,Jagged2)和Delta样家族(DLL1,DLL3,DLL4).Notch信号途径涉及一些蛋白质裂解过程,随后反式作用因子RBP-J及协同激活因子MAML等参与,最终导致靶基因的转录.在早期T细胞发育过程中起关键作用,还调节外周T细胞的活化增殖以及诱导Th细胞亚群的分化.Notch信号途径对转录因子GATA-3激活而诱导的Th2细胞分化非常重要.     

Role of CD45 Signaling Pathway in Galactoxylomannan-Induced T Cell Damage

Previously, we reported that Galactoxylomannan (GalXM) activates the extrinsic and intrinsic apoptotic pathways through an interaction with the glycoreceptors on T cells. In this study we establish the role of the glycoreceptor CD45 in GalXM-induced T cell apoptosis, using CD45^+/+ and CD45^−/− cell lines, derived from BW5147 murine T cell lymphoma. Our results show that whereas CD45 expression is not required for GalXM association by the cells, it is essential for apoptosis induction. In CD45^+/+ cells, CD45 triggering by GalXM reduces the activation of Lck, ZAP70 and Erk1/2. Conversely, in CD45^−/− cells, Lck was hyperphosphorylated and did not show any modulation after GalXM stimulation. On the whole, our findings provide evidence that the negative regulation of Lck activation occurs via CD45 engagement. This appears to be related to the capacity of GalXM to antagonize T cell activation and induce T cell death. Overall this mechanism may be responsible for the immune paralysis that follows GalXM administration and could explain the powerful immunosuppression that accompanies cryptococcosis.     

Phase 1 Study of a Sulforaphane-Containing Broccoli Sprout Homogenate for Sickle Cell Disease

Sickle cell disease (SCD) is the most common inherited hemoglobinopathy worldwide. Our previous results indicate that the reduced oxidative stress capacity of sickle erythrocytes may be caused by decreased expression of NRF2 (Nuclear factor (erythroid-derived 2)-like 2), an oxidative stress regulator. We found that activation of NRF2 with sulforaphane (SFN) in erythroid progenitors significantly increased the expression of NRF2 targets HMOX1, NQO1, and HBG1 (subunit of fetal hemoglobin) in a dose-dependent manner. Therefore, we hypothesized that NRF2 activation with SFN may offer therapeutic benefits for SCD patients by restoring oxidative capacity and increasing fetal hemoglobin concentration. To test this hypothesis, we performed a Phase 1, open-label, dose-escalation study of SFN, contained in a broccoli sprout homogenate (BSH) that naturally contains SFN, in adults with SCD. The primary and secondary study endpoints were safety and physiological response to NRF2 activation, respectively. We found that BSH was well tolerated, and the few adverse events that occurred during the trial were not likely related to BSH consumption. We observed an increase in the mean relative whole blood mRNA levels for the NRF2 target HMOX1 (p = 0.02) on the last day of BSH treatment, compared to pre-treatment. We also observed a trend toward increased mean relative mRNA levels of the NRF2 target HBG1 (p = 0.10) from baseline to end of treatment, but without significant changes in HbF protein. We conclude that BSH, in the provided doses, is safe in stable SCD patients and may induce changes in gene expression levels. We therefore propose investigation of more potent NRF2 inducers, which may elicit more robust physiological changes and offer clinical benefits to SCD patients.Trial Registration: ClinicalTrials.gov {"type":"clinical-trial","attrs":{"text":"NCT01715480","term_id":"NCT01715480"}}NCT01715480     

钙信号重构调控肿瘤发生发展

钙离子是细胞内最重要的第二信使之一,对肿瘤细胞的发生发展起着重要的调控作用.无节制的增殖、降低的凋亡和高度的转移能力是肿瘤细胞的三大特征.细胞过度增殖需要胞浆钙升高,而逃避凋亡则需要较低的胞浆钙.在肿瘤发生发展过程中,早期过表达的胞膜钙通道倾向于调低,而内质网钙通道表达升高,并伴有通道定位的改变和新通道的形成.迁移细胞中的微区钙信号可决定细胞转移的方向.综上所述,钙信号可作为药物靶点,在肿瘤药物研发中具有一定的潜力.     

A c-Myc and Surface CD19 Signaling Amplification Loop Promotes B Cell Lymphoma Development and Progression in Mice

Malignant B cells responding to external stimuli are likely to gain a growth advantage in vivo. These cells may therefore maintain surface CD19 expression to amplify transmembrane signals and promote their expansion and survival. To determine whether CD19 expression influences this process, Eμ-Myc transgenic (c-Myc(Tg)) mice that develop aggressive and lethal B cell lymphomas were made CD19 deficient (c-Myc(Tg)CD19(-/-)). Compared with c-Myc(Tg) and c-Myc(Tg)CD19(+/-) littermates, the median life span of c-Myc(Tg)CD19(-/-) mice was prolonged by 81-83% (p < 0.0001). c-Myc(Tg)CD19(-/-) mice also lived 42% longer than c-Myc(Tg) littermates following lymphoma detection (p < 0.01). Tumor cells in c-Myc(Tg) and c-Myc(Tg)CD19(-/-) mice were B lineage derived, had a similar phenotype with a large blastlike appearance, invaded multiple lymphoid tissues, and were lethal when adoptively transferred into normal recipient mice. Importantly, reduced lymphomagenesis in c-Myc(Tg)CD19(-/-) mice was not due to reductions in early B cell numbers prior to disease onset. In mechanistic studies, constitutive c-Myc expression enhanced CD19 expression and phosphorylation on active sites. Reciprocally, CD19 expression in c-Myc(Tg) B cells enhanced c-Myc phosphorylation at regulatory sites, sustained higher c-Myc protein levels, and maintained a balance of cyclin D2 expression over that of cyclin D3. These findings define a new and novel c-Myc:CD19 regulatory loop that positively influences B cell transformation and lymphoma progression.     

Vibration Sensitivity and a Computational Theory for Prey-Localizing Behavior in Sand Scorpions

As burrowing, nocturnal predators of small arthropods, sandscorpions have evolved exquisite sensitivity to vibrationalinformation that comes to them through the substrate they liveon, dry sand. Over distances of a few decimeters, sand conductslow velocity (50 m/sec) surface (Rayleigh) waves of sufficientamplitude and bandwidth (200<f<500 Hz) to be biologicallydetectable. Eight acceleration-sensitive receptors (slit sensilla)at the tips of the scorpion's circularly arranged legs detectsurface waves generated by prey movements or "juddering" signalsfrom other scorpions. From this input alone, direction of thedisturbance source is calculated up to 20 cm distance. By ablatingslit sensilla in various combinations on the eight legs, thecontribution each makes in computing target location can beassessed. Other behavioral experiments show that differentialtiming of surface wave arrival at each sensor is most likelythe cue that determines target location. Given the simplicityof this sensory system, a computational theory to account forwave source localization has been developed using a populationof second-order neurons, each receiving excitatory input fromone vibration receptor and inhibition from the triad of receptorsopposite to it in the eight-element array. Input from a passingsurface wave opens and closes a time widow, the width of whichdetermines the firing probability of second-order neurons. Targetdirection is encoded as the relative excitation of these neurons,and stochastic optimization tunes the relative strengths ofexcitatory and inhibitory inputs for accuracy of response. Theexcellent agreement between predictions of the model and observedbehavior of sand scorpions confirms a simple theory for computationalmapping of surface vibration space.     

The Role of Informative and Ambiguous Feedback in Avoidance Behavior: Empirical and Computational Findings

Avoidance behavior is a critical component of many psychiatric disorders, and as such, it is important to understand how avoidance behavior arises, and whether it can be modified. In this study, we used empirical and computational methods to assess the role of informational feedback and ambiguous outcome in avoidance behavior. We adapted a computer-based probabilistic classification learning task, which includes positive, negative and no-feedback outcomes; the latter outcome is ambiguous as it might signal either a successful outcome (missed punishment) or a failure (missed reward). Prior work with this task suggested that most healthy subjects viewed the no-feedback outcome as strongly positive. Interestingly, in a later version of the classification task, when healthy subjects were allowed to opt out of (i.e. avoid) responding, some subjects (“avoiders”) reliably avoided trials where there was a risk of punishment, but other subjects (“non-avoiders”) never made any avoidance responses at all. One possible interpretation is that the “non-avoiders” valued the no-feedback outcome so positively on punishment-based trials that they had little incentive to avoid. Another possible interpretation is that the outcome of an avoided trial is unspecified and that lack of information is aversive, decreasing subjects’ tendency to avoid. To examine these ideas, we here tested healthy young adults on versions of the task where avoidance responses either did or did not generate informational feedback about the optimal response. Results showed that provision of informational feedback decreased avoidance responses and also decreased categorization performance, without significantly affecting the percentage of subjects classified as “avoiders.” To better understand these results, we used a modified Q-learning model to fit individual subject data. Simulation results suggest that subjects in the feedback condition adjusted their behavior faster following better-than-expected outcomes, compared to subjects in the no-feedback condition. Additionally, in both task conditions, “avoiders” adjusted their behavior faster following worse-than-expected outcomes, and treated the ambiguous no-feedback outcome as less rewarding, compared to non-avoiders. Together, results shed light on the important role of ambiguous and informative feedback in avoidance behavior.     

细胞骨架和cAMP/PKA信号通路的互动效应调控细胞行为的研究进展

细胞骨架的运动变化是一个多蛋白和多步骤参与的复杂过程。研究表明,环状腺苷酸（cyclic adenosine monophosphate,cAMP）作为第二信使,参与调控多种细胞信号转导,从而调控细胞骨架重排过程及其介导的细胞分裂、迁移、分化和黏附等。然而,另有文献报道,细胞骨架纤维排列首先通过影响信号通路中蛋白激酶的活性,进而影响细胞行为。该文结合课题组的实验结果就细胞骨架和cAMP信号通路互动效应调控细胞行为的研究进展作一综述。     

Wnt信号通路在骨细胞生物学及骨疾病中作用的研究进展

Wnt信号通路参与细胞增殖、胚胎发育、组织再生和干细胞维持等多种生物学过程。近年来,Wnt信号通路在骨骼系统发育及代谢过程中的作用引起广泛关注。探讨Wnt信号通路调节成骨细胞分化、增殖以及维持整个骨骼系统平衡的分子机制,对于临床治疗各种骨疾病(如骨质疏松)具有重要意义。     

Role of Type I Interferon Receptor Signaling on NK Cell Development and Functions

Type I interferons (IFN) are unique cytokines transcribed from intronless genes. They have been extensively studied because of their anti-viral functions. The anti-viral effects of type I IFN are mediated in part by natural killer (NK) cells. However, the exact contribution of type I IFN on NK cell development, maturation and activation has been somewhat difficult to assess. In this study, we used a variety of approaches to define the consequences of the lack of type I interferon receptor (IFNAR) signaling on NK cells. Using IFNAR deficient mice, we found that type I IFN affect NK cell development at the pre-pro NK stage. We also found that systemic absence of IFNAR signaling impacts NK cell maturation with a significant increase in the CD27⁺CD11b⁺ double positive (DP) compartment in all organs. However, there is tissue specificity, and only in liver and bone marrow is the maturation defect strictly dependent on cell intrinsic IFNAR signaling. Finally, using adoptive transfer and mixed bone marrow approaches, we also show that cell intrinsic IFNAR signaling is not required for NK cell IFN-γ production in the context of MCMV infection. Taken together, our studies provide novel insights on how type I IFN receptor signaling regulates NK cell development and functions.