A shared mechanism for TNP-ATP recognition by members of the P2X receptor family

P2X receptors (P2X1-7) are non-selective cation channels involved in many physiological activities such as synaptic transmission, immunological modulation, and cardiovascular function. These receptors share a conserved mechanism to sense extracellular ATP. TNP-ATP is an ATP derivative acting as a nonselective competitive P2X antagonist. Understanding how it occupies the orthosteric site in the absence of agonism may help reveal the key allostery during P2X gating. However, TNP-ATP/P2X complexes (TNP-ATP/human P2X3 (hP2X3) and TNP-ATP/chicken P2X7 (ckP2X7)) with distinct conformations and different mechanisms of action have been proposed. Whether these represent species and subtype variations or experimental differences remains unclear. Here, we show that a common mechanism of TNP-ATP recognition exists for the P2X family members by combining enhanced conformation sampling, engineered disulfide bond analysis, and covalent occupancy. In this model, the polar triphosphate moiety of TNP-ATP interacts with the orthosteric site, while its TNP-moiety is deeply embedded in the head and dorsal fin (DF) interface, creating a restrictive allostery in these two domains that results in a partly enlarged yet ion-impermeable pore. Similar results were obtained from multiple P2X subtypes of different species, including ckP2X7, hP2X3, rat P2X2 (rP2X2), and human P2X1 (hP2X1). Thus, TNP-ATP uses a common mechanism for P2X recognition and modulation by restricting the movements of the head and DF domains which are essential for P2X activation. This knowledge is applicable to the development of new P2X inhibitors.

Altered allostery of the left flipper domain underlies the weak ATP response of rat P2X5 receptors

Although the extracellular ATP-gated cation channel purinergic receptor P2X5 is widely expressed in heart, skeletal muscle, and immune and nervous systems in mammals, little is known about its functions and channel-gating activities. This lack of knowledge is due to P2X5's weak ATP responses in several mammalian species, such as humans, rats, and mice. WT human P2X5 (hP2X5Δ328-349) does not respond to ATP, whereas a full-length variant, hP2X5 (hP2X5-FL), containing exon 10 encoding the second hP2X5 transmembrane domain (TM2), does. However, although rat P2X5 (rP2X5) has a full-length TM2, ATP induces only weak currents in rP2X5, which prompted us to investigate the mechanism underlying this small ATP response. Here, we show that single replacements of specific rP2X5 residues with the corresponding residues in hP2X5 (S191F or F195H) significantly enhance the current amplitude of rP2X5. Using a combination of engineered disulfide cross-linking, single-channel recording, and molecular modeling, we interrogated the effects of S191F and F195H substitutions on the allostery of the left flipper (LF) domain. On the basis of our findings, we propose that the bound ATP-induced distinct allostery of the LF domain with that of other functional subtypes has caused the weak ATP response of rP2X5 receptors. The findings of our study provide the prerequisite for future transgenic studies on the physiological and pathological functions of P2X5 receptors.

Single-photon avalanche diodes in 0.18-μm high-voltage CMOS technology

We have designed and fabricated high-performance single-photon avalanche diodes (SPADs) by using 0.18-µm high-voltage CMOS technology. Without any technology customization, the SPADs have low dark-count rate, high photon-detection probability, low afterpulsing probability, and acceptable timing jitter and breakdown voltage. Our design provides a low-cost and high-performance SPAD for various applications.

Intersubunit physical couplings fostered by the left flipper domain facilitate channel opening of P2X4 receptors

P2X receptors are ATP-gated trimeric channels with important roles in diverse pathophysiological functions. A detailed understanding of the mechanism underlying the gating process of these receptors is thus fundamentally important and may open new therapeutic avenues. The left flipper (LF) domain of the P2X receptors is a flexible loop structure, and its coordinated motions together with the dorsal fin (DF) domain are crucial for the channel gating of the P2X receptors. However, the mechanism underlying the crucial role of the LF domain in the channel gating remains obscure. Here, we propose that the ATP-induced allosteric changes of the LF domain enable it to foster intersubunit physical couplings among the DF and two lower body domains, which are pivotal for the channel gating of P2X4 receptors. Metadynamics analysis indicated that these newly established intersubunit couplings correlate well with the ATP-bound open state of the receptors. Moreover, weakening or strengthening these physical interactions with engineered intersubunit metal bridges remarkably decreased or increased the open probability of the receptors, respectively. Further disulfide cross-linking and covalent modification confirmed that the intersubunit physical couplings among the DF and two lower body domains fostered by the LF domain at the open state act as an integrated structural element that is stringently required for the channel gating of P2X4 receptors. Our observations provide new mechanistic insights into P2X receptor activation and will stimulate development of new allosteric modulators of P2X receptors.

Exploration of the Peptide Recognition of an Amiloride-sensitive FMRFamide Peptide-gated Sodium Channel

FMRFamide (Phe-Met-Arg-Phe-NH2)-activated sodium channel (FaNaC) is an amiloride-sensitive sodium channel activated by endogenous tetrapeptide in invertebrates, and belongs to the epithelial sodium channel/degenerin (ENaC/DEG) superfamily. The ENaC/DEG superfamily differs markedly in its means of activation, such as spontaneously opening or gating by mechanical stimuli or tissue acidosis. Recently, it has been observed that a number of ENaC/DEG channels can be activated by small molecules or peptides, indicating that the ligand-gating may be an important feature of this superfamily. The peptide ligand control of the channel gating might be an ancient ligand-gating feature in this superfamily. Therefore, studying the peptide recognition of FaNaC channels would advance our understanding of the ligand-gating properties of this superfamily of ion channels. Here we demonstrate that Tyr-131, Asn-134, Asp-154, and Ile-160, located in the putative upper finger domain ofHelix aspersaFaNaC (HaFaNaC) channels, are key residues for peptide recognition of this ion channel. Two HaFaNaC specific-insertion motifs among the ENaC/DEG superfamily, residing at the putative α4-α5 linker of the upper thumb domain and the α6-α7 linker of the upper knuckle domain, are also essential for the peptide recognition of HaFaNaC channels. Chemical modifications and double mutant cycle analysis further indicated that those two specific inserts and key residues in the upper finger domain together participate in peptide recognition of HaFaNaC channels. This ligand recognition site is distinct from that of acid-sensing ion channels (ASICs) by a longer distance between the recognition site and the channel gate, carrying useful information about the ligand gating and the evolution of the trimeric ENaC/DEG superfamily of ion channels.

A Highly Conserved Salt Bridge Stabilizes the Kinked Conformation of β2,3-Sheet Essential for Channel Function of P2X4 Receptors

Significant progress has been made in understanding the roles of crucial residues/motifs in the channel function of P2X receptors during the pre-structure era. The recent structural determination of P2X receptors allows us to reevaluate the role of those residues/motifs. Residues Arg-309 and Asp-85 (rat P2X4 numbering) are highly conserved throughout the P2X family and were involved in loss-of-function polymorphism in human P2X receptors. Previous studies proposed that they participated in direct ATP binding. However, the crystal structure of P2X demonstrated that those two residues form an intersubunit salt bridge located far away from the ATP-binding site. Therefore, it is necessary to reevaluate the role of this salt bridge in P2X receptors. Here, we suggest the crucial role of this structural element both in protein stability and in channel gating rather than direct ATP interaction and channel assembly. Combining mutagenesis, charge swap, and disulfide cross-linking, we revealed the stringent requirement of this salt bridge in normal P2X4 channel function. This salt bridge may contribute to stabilizing the bending conformation of the β2,3-sheet that is structurally coupled with this salt bridge and the α2-helix. Strongly kinked β2,3 is essential for domain-domain interactions between head domain, dorsal fin domain, right flipper domain, and loop β7,8 in P2X4 receptors. Disulfide cross-linking with directions opposing or along the bending angle of the β2,3-sheet toward the α2-helix led to loss-of-function and gain-of-function of P2X4 receptors, respectively. Further insertion of amino acids with bulky side chains into the linker between the β2,3-sheet or the conformational change of the α2-helix, interfering with the kinked conformation of β2,3, led to loss-of-function of P2X4 receptors. All these findings provided new insights in understanding the contribution of the salt bridge between Asp-85 and Arg-309 and its structurally coupled β2,3-sheet to the function of P2X receptors.

Neutrophil-lymphocyte ratio: a controversial marker in predicting Crohn's disease severity

Peripheral blood-derived inflammation-based scores such as the neutrophil-lymphocyte ratio (NLR) have recently been proposed as prognostic markers in ulcerative colitis. In some previous serological markers are commonly used to detect the severity of the Crohn's disease (CD), but their sensitivity and specificity are relatively low. So we want to use simple indicators which are easy to obtain to predict disease severity. Now, we investigated and compared the capacity of NLR and other inflammatory markers in detecting CD activity and differentiating CD patients from healthy controls. These CD patients had not received corticosteroid or immunosuppressive drugs within a defined period of time. Data from our hospital between 2010 and 2012 was used. Neutrophil-lymphocyte ratio (NLR), C-reactive protein (CRP), erythrocyte sedimentation rate (ESR), white blood cells (WBC), platelet count and albumin were measured in 44 patients with active CD, 66 patients with inactive CD, and 55 healthy blood donors. Disease activity was assessed by the Crohn's Disease Activity Index. In the active CD group, NLR values were found to be elevated compared to inactive CD patients and controls (6.00±7.38, 5.53±6.18 and 1.84±0.85, respectively), but statistical difference was not found between active and inactive CD groups. The overall accuracy of NLR (cutoff: 2.13 fl), CRP (cutoff: 10.5 mg/dl), ESR (cutoff: 19.5 mm/hour) and WBC (cutoff: 9.2 × 10(9)/l) in differentiating CD patients from healthy controls was 80.9%, 67.3%, 71% and 60% respectively. NLR values were found to be correlated with WBC and CRP levels. NLR increased in CD patients compared with healthy subjects. NLR had the best accuracy in determination of CD patients and healthy controls. NLR did not show a discriminative value in disease activity.

Intra-thyroid thyroglossal duct cyst: a case report and review of literature

Thyroglossal duct cyst is the most common congenital cyst in the head and neck, which is defined usually occurring in children. However, intra-thyroid thyroglossal duct cyst in an adult is unusually found. Here we describe a case of a 45-year-old woman who was found neck mass along the midline for 5 years. During the surgery we found a separated nodule in the left inferior pole of the thyroid. Surprisingly the diagnosis of the nodule was confirmed by pathology and histological examination demonstrating that it was the thyroglossal duct cyst. Intra-thyroid thyroglossal duct cyst in an adult is a rare finding, with few cases reported. For it is generally thought that any thyroid tissue found in the lateral aspect of the neck may indicate metastatic deposits from well-differentiated thyroid carcinoma. Although pathogenesis of an alone thyroglossal duct cyst in the left inferior pole of the thyroid remains unknown, our case could suggest thyroglossal duct cyst should not be excluded in the differential diagnosis of lateral neck masses especially when it simulates nodules in the thyroid.

Incidence and risk factors of early deep venous thrombosis after varicose vein surgery with routine use of a tourniquet

INTRODUCTION

The incidence of early deep venous thrombosis (DVT) following varicose vein surgery (traditional open stripping) with routine use of a tourniquet remains unknown.

MATERIALS AND METHODS

A retrospective analysis of all patients who underwent varicose vein surgery with a tourniquet in the authors' unit between 1 January 2012 and 30 November 2013 was undertaken. Cases of postoperative DVT were identified from the unit database, and re-assessments conducted 1, 3 and 6 months after the initial diagnosis were recorded from the outpatient department.

RESULTS

Out of 1461 patients, 113 (7.7%) developed postoperative DVT. Nineteen (1.3%) patients had proximal DVT, and 94 (6.4%) patients had isolated distal DVT. The risk factors for postoperative DVT included old age (≥65 years), female sex and gastrocnemius vein dilation (GVD). GVD was found to be a significant independent risk factor for the occurrence of DVT, with an odds ratio of 2.437 (95% confidence interval 1.644-3.611). Five patients with distal DVT (5.7%) and eight patients with proximal DVT (44.4%) still exhibited a thrombus at 6-month follow-up, but with decreased size and at various stages of resolution.

CONCLUSIONS

This study found a higher incidence of postoperative DVT (7.7%) with routine use of a tourniquet during varicose vein surgery than has been reported previously. Among the factors examined, GVD had the highest predictive power for postoperative DVT. Both distal and proximal DVT were associated with acceptable outcomes.

MicroRNA-155 promotes the proliferation and invasion abilities of colon cancer cells by targeting quaking

The increasing expression of microRNA‑155 (miR‑155) and decreasing expression of RNA‑binding protein quaking (QKI) in colon cells have been observed previously. In this study, we attempted to establish the correlation between miR‑155 and QKI. In addition, we assessed whether the expression of miR‑155 and QKI is linked to the proliferation and invasion capabilities of colon cells. Firstly, nineteen tumor samples, divided into two groups according to the presence or absence of lymphatic metastasis, were obtained from colon cancer patients at the First Affiliated Hospital of Wenzhou Medical University, China. The expression level of miR‑155 and QKI was measured by quantitative polymerase chain reaction (qPCR). Secondly, the GES‑1, SW480 and COLO205 cell lines were cultured and the expression level of QKI and miR‑155 was also assessed by qPCR. Thirdly, a luciferase reporter gene assay was performed to detect the association between miR‑155 and QKI, and qPCR and western blot analysis were performed to confirm the effects of miR‑155 on the expression of QKI at the mRNA and protein level. Subsequently, the SW480 cells were used in the following experiments. Following treatment with miR‑155 inhibitor and QKI overexpression vector, western blot analysis, propidium iodide (PI) staining and a cell scratch assay were carried out to assess the effects of miR‑155 on the proliferation and invasion potential of colon cancer cells. qPCR findings revealed higher miR‑155 expression and lower QKI expression in colon cancer tissues as well as the colon cancer cell lines SW480 and COLO205. The relative luciferase activity of the 3' untranslated region (3'UTR) was decreased by approximately 45% when SW480 cells stimulated by mimic‑miR‑155 were combined with the wild‑type 3'UTR constructs. In addition, when the cells were treated with mimic‑miR‑155, QKI expression was significantly decreased at the mRNA and protein level. These outcomes revealed that miR‑155 decreased the production of QKI by acting on the 3'UTR of the QKI gene. Furthermore, PI staining and the cell scratch assay revealed that miR‑155 influenced the cell cycle and invasion abilities of colon cancer cells by directly targeting QKI and decreased the production of QKI by acting on the 3'UTR of the QKI gene. This study has demonstrated the correlation between miR‑155 and QKI, in which miR‑155 regulates the cell cycle and invasion ability of colon cancer cells via the modulation of QKI expression. Our study provides novel therapeutic strategies for colon cancer therapy.

Relative motions between left flipper and dorsal fin domains favour P2X4 receptor activation

Channel gating in response to extracellular ATP is a fundamental process for the physiological functions of P2X receptors. Here we identify coordinated allosteric changes in the left flipper (LF) and dorsal fin (DF) domains that couple ATP-binding to channel gating. Engineered disulphide crosslinking or zinc bridges between the LF and DF domains that constrain their relative motions significantly influence channel gating of P2X4 receptors, confirming the essential role of these allosteric changes. ATP-binding-induced alterations in interdomain hydrophobic interactions among I208, L217, V291 and the aliphatic chain of K193 correlate well with these coordinated relative movements. Mutations on those four residues lead to impaired or fully abolished channel activations of P2X4 receptors. Our data reveal that ATP-binding-induced altered interdomain hydrophobic interactions and the concomitant coordinated motions of LF and DF domains are allosteric events essential for the channel gating of P2X4 receptors.

Inherent dynamics of head domain correlates with ATP-recognition of P2X4 receptors: insights gained from molecular simulations

P2X receptors are ATP-gated ion channels involved in many physiological functions, and determination of ATP-recognition (AR) of P2X receptors will promote the development of new therapeutic agents for pain, inflammation, bladder dysfunction and osteoporosis. Recent crystal structures of the zebrafish P2X4 (zfP2X4) receptor reveal a large ATP-binding pocket (ABP) located at the subunit interface of zfP2X4 receptors, which is occupied by a conspicuous cluster of basic residues to recognize triphosphate moiety of ATP. Using the engineered affinity labeling and molecular modeling, at least three sites (S1, S2 and S3) within ABP have been identified that are able to recognize the adenine ring of ATP, implying the existence of at least three distinct AR modes in ABP. The open crystal structure of zfP2X4 confirms one of three AR modes (named AR1), in which the adenine ring of ATP is buried into site S1 while the triphosphate moiety interacts with clustered basic residues. Why architecture of ABP favors AR1 not the other two AR modes still remains unexplored. Here, we examine the potential role of inherent dynamics of head domain, a domain involved in ABP formation, in AR determinant of P2X4 receptors. In silico docking and binding free energy calculation revealed comparable characters of three distinct AR modes. Inherent dynamics of head domain, especially the downward motion favors the preference of ABP for AR1 rather than AR2 and AR3. Along with the downward motion of head domain, the closing movement of loop139-146 and loop169-183, and structural rearrangements of K70, K72, R298 and R143 enabled ABP to discriminate AR1 from other AR modes. Our observations suggest the essential role of head domain dynamics in determining AR of P2X4 receptors, allowing evaluation of new strategies aimed at developing specific blockers/allosteric modulators by preventing the dynamics of head domain associated with both AR and channel activation of P2X4 receptors.

The role of MAP1A light chain 2 in synaptic surface retention of Cav2.2 channels in hippocampal neurons

Ca(v)2.2 channels are localized at nerve terminals where they play a critical role in neurotransmission. However, the determinant that controls surface retention of these channels has not been identified. Here, we report that presynaptic surface localization of Ca(v)2.2 is mediated through its interaction with light chain 2 (LC2) of microtubule-associated protein MAP1A. Deletion of a 23-residue binding domain within the Ca(v)2.2 C terminus resulted in reduced synaptic distribution of the mutant channels. Using an antibody generated against an extracellular epitope of Ca(v)2.2, we demonstrate that interfering the interaction with LC2 reduced surface expression of endogenous Ca(v)2.2 at presynaptic boutons. In addition, the disruption of LC2-Ca(v)2.2 coupling reduced Ca(2+)-influx into nerve terminals through Ca(v)2.2 and impaired activity-dependent FM4-64 uptake. The treatments of neurons with Latrunculin A to disrupt actin filaments resulted in reduced density of surface Ca(v)2.2-positive boutons. Furthermore, LC2NT, a LC2 truncated mutant lacking the actin-binding domain, could not rescue Ca(v)2.2 surface expression after suppressing LC2 expression with RNAi. Because actin filaments are major cytomatric components at the presynaptic boutons, these observations suggest a mechanism by which LC2 provides anchoring of surface Ca(v)2.2 to the actin cytoskeleton, thus contributing to presynaptic function.

Expression and localization of p80 interleukin-1 receptor protein in the rat spinal cord

The biological effects of interleukin (IL)-1 are mediated by two distinct receptors, the p80 or type I (IL-1RI) and p68 or type II (IL-1RII) receptors. Because IL-1RII has a short, 29-amino acid cytoplasmic domain which may not be sufficient for signaling, there is considerable evidence indicating that IL-1 may signal exclusively through the IL-1RI receptor. Here, we report the expression, distribution, and cellular localization of the IL-1RI protein in the adult rat spinal cord in vivo and embryonic spinal cord in vitro. We found that IL-1RI was expressed in both the gray and white matter throughout the entire length of the spinal cord and was localized in neurons of the anterior horn, astrocytes, oligodendrocytes, and central canal ependymal cells. Interestingly, resting microglia were negative for IL-1RI. In primary cultures obtained from the embryonic day (E) 15 rats, IL-1RI was expressed in neurons, astrocytes, and oligodendrocytes as well as microglia. These data provide both in vivo and in vitro evidence that neurons and glial cells express the IL-1RI proteins. The differential expression of IL-1RI in the developing, but not mature, microglia may indicate the difference of these cells in response to IL-1 stimuli during maturation. The distribution and cellular localization of IL-1RI proteins in the spinal cord provide a molecular basis for understanding the reciprocal interaction between the immune and the central nervous systems.

Upregulation of type I interleukin-1 receptor after traumatic spinal cord injury in adult rats

Post-traumatic inflammation response has been implicated in secondary injury mechanisms after spinal cord injury (SCI). Interleukin-1 (IL-1) is a key inflammatory mediator that is increasingly expressed after SCI. The action of IL-1 is mediated through its functional receptor, type I interleukin-1 receptor (IL-1RI). However, whether this receptor is expressed after SCI remains to be elucidated. In the present study, the temporospatial expression of IL-1RI was detected in rats that received a moderate contusive SCI (a 10 g rod dropped at a height of 12.5 mm) at the ninth to tenth thoracic vertebral level using a widely used New York University impact device. Our study demonstrated that IL-1RI was slightly increased at 4 h post-injury compared to the normal or sham-operated controls, reached the peak at 8 h at mRNA level (4.44-fold, P<0.01) and 1 d at protein level (2.62-fold, P<0.01). IL-1RI remained at its elevated levels for a relatively long duration (4 h-7 days). Spatially, IL-1RI was observed throughout the entire length of a 10 mm-long cord segment containing the injury epicenter. Colocalization of IL-1RI was found in neurons, oligodendrocytes, astrocytes, and activated microglia. Our results suggest that the elevated expression of IL-1RI after SCI may contribute to posttraumatic inflammation responses of IL-1.

The mood stabilizer valproic acid activates mitogen-activated protein kinases and promotes neurite growth

The mood-stabilizing agents lithium and valproic acid (VPA) increase DNA binding activity and transactivation activity of AP-1 transcription factors, as well as the expression of genes regulated by AP-1, in cultured cells and brain regions involved in mood regulation. In the present study, we found that VPA activated extracellular signal-regulated kinase (ERK), a kinase known to regulate AP-1 function and utilized by neurotrophins to mediate their diverse effects, including neuronal differentiation, neuronal survival, long term neuroplasticity, and potentially learning and memory. VPA-induced activation of ERK was blocked by the mitogen-activated protein kinase/ERK kinase inhibitor PD098059 and dominant-negative Ras and Raf mutants but not by dominant-negative stress-activated protein kinase/ERK kinase and mitogen-activated protein kinase kinase 6 mutants. VPA also increased the expression of genes regulated by the ERK pathway, including growth cone-associated protein 43 and Bcl-2, promoted neurite growth and cell survival, and enhanced norepinephrine uptake and release. These data demonstrate that VPA is an ERK pathway activator and produces neurotrophic effects.

Mood stabilizers regulate cytoprotective and mRNA-binding proteins in the brain: long-term effects on cell survival and transcript stability

Manic depressive illness (MDI) is a common, severe, chronic and often life-threatening illness. Despite well-established genetic diatheses and extensive research, the biochemical abnormalities underlying the predisposition to, and the pathophysiology of, these disorders remain to be clearly established. Despite formidable obstacles in our attempts to understand the underlying neurobiology of this illness, there is currently considerable excitement about the progress that is being made using novel strategies to identify changes in gene expression that may have therapeutic relevance in the long-term treatment of MDI. In this paper, we describe our recent research endeavours utilizing newer technologies, including a concerted series of mRNA RT-PCR studies, which has led to the identification of novel, hitherto completely unexpected targets for the long-term actions of mood stabilizers - the major cytoprotective protein bcl-2, a human mRNA binding (and stabilizing) protein, AUH, and a Rho kinase. These results add to the growing body of data suggesting that mood stabilizers may bring about some of their long-term benefits by enhancing neuroplasticity and cellular resilience. These results are noteworthy since recent morphometric brain imaging and post-mortem studies have demonstrated that MDI is associated with the atrophy and/or loss of neurons and glia. The development of novel treatments which more directly target molecules involved in critical CNS cell survival and cell death pathways have the potential to enhance neuroplasticity and cellular resilience, and thereby modulate the long-term course and trajectory of these devastating illnesses.

The mood-stabilizing agent valproate inhibits the activity of glycogen synthase kinase-3

Valproic acid (VPA) is a potent broad-spectrum anti-epileptic with demonstrated efficacy in the treatment of bipolar affective disorder. It has previously been demonstrated that both VPA and lithium increase activator protein-1 (AP-1) DNA binding activity, but the mechanisms underlying these effects have not been elucidated. However, it is known that phosphorylation of c-jun by glycogen synthase kinase (GSK)-3beta inhibits AP-1 DNA binding activity, and lithium has recently been demonstrated to inhibit GSK-3beta. These results suggest that lithium may increase AP-1 DNA binding activity by inhibiting GSK-3beta. In the present study, we sought to determine if VPA, like lithium, regulates GSK-3. We have found that VPA concentration-dependently inhibits both GSK-3alpha and -3beta, with significant effects observed at concentrations of VPA similar to those attained clinically. Incubation of intact human neuroblastoma SH-SY5Y cells with VPA results in an increase in the subsequent in vitro recombinant GSK-3beta-mediated 32P incorporation into two putative GSK-3 substrates (approximately 85 and 200 kDa), compatible with inhibition of endogenous GSK-3beta by VPA. Consistent with GSK-3beta inhibition, incubation of SH-SY5Y cells with VPA results in a significant time-dependent increase in both cytosolic and nuclear beta-catenin levels. GSK-3beta plays a critical role in the CNS by regulating various cytoskeletal processes as well as long-term nuclear events and is a common target for both lithium and VPA; inhibition of GSK-3beta in the CNS may thus underlie some of the long-term therapeutic effects of mood-stabilizing agents.

Cis-trans complementation of DQA1-DQB1 genes are modulated by DQ alleles: an immunogenetics analysis of DQ association with the down-regulatory function of CD8 cells in trichosanthin-induced immunosuppression

The initiation of a CD8 cell-mediated pathway (M+) was adopted as a phenotypic trait to analyse genetic predisposition in trichosanthin (Tk)-induced immuno-suppression. Tk is a natural protein antigen with 247 amino acid residues. Based on DNA typing for DR, DQ, DP and TAP genes, data in this paper indicate that only DQ genes were primarily involved and that the alleles DQA1*0501 and DQB1*0201 were strongly associated with the M+ phenotype in cis (on DR3 haplotype) or trans (on DR5/DR7 heterozygotes) complementation. This is consistent with our observation that only the DQ-positive cells were capable of expanding after being co-cultured with Tk for 96 h. Two points of interest were noted. (1) The susceptible haplotype DRB1*0301-DQA1*0501-DQB1*0201 showed an association with the M+ phenotype only if combined with DRB1*04-, DRB1*08-, or DRB1*09-related haplotypes. When co-presented with DRB1*11-, DRB1*15-, DRB1*07-related haplotypes, however, no cis complementation could be detected. A detailed analysis of the association patterns indicated that the DQB1 locus of the non-susceptible haplotypes was the main factor for up- or down-modulation. (2) For M+ phenotype-related trans complementation in Tk-induced suppression, it was found that not only DQA1*0501-DQB1*0201 (DR5/7) alleles, but also associated DQA1*0301-DQB1*0201 (DR4/7, 9/7) alleles, were involved. The allele DQB1*0201 was not associated with the DQA1 alleles in DRB1*01-, DRB1*15-, DRB1*13-, DRB1*07-related haplotypes. The results obtained indicate that there are some additional genetic factors involved in the functional expression of cis and trans complementation of DQA1 and DQB1 genes, among which the DQ alleles play a critical role as self-regulators.

The mood-stabilizing agents lithium and valproate robustly increase the levels of the neuroprotective protein bcl-2 in the CNS

Differential display of mRNA was used to identify concordant changes in gene expression induced by two mood-stabilizing agents, lithium and valproate (VPA). Both treatments, on chronic administration, increased mRNA levels of the transcription factor polyomavirus enhancer-binding protein (PEBP) 2beta in frontal cortex (FCx). Both treatments also increased the DNA binding activity of PEBP2 alphabeta and robustly increased the levels of bcl-2 (known to be transcriptionally regulated by PEBP2) in FCx. Immunohistochemical studies revealed a marked increase in the number of bcl-2-immunoreactive cells in layers 2 and 3 of FCx. These novel findings represent the first report of medication-induced increases in CNS bcl-2 levels and may have implications not only for mood disorders, but also for long-term treatment of various neurodegenerative disorders.

Valproate robustly enhances AP-1 mediated gene expression

Valproic acid (VPA) is a potent broad spectrum anticonvulsant with demonstrated efficacy in the treatment of Bipolar Affective Disorder, but the biochemical basis for VPA's antimanic or mood-stabilizing actions have not been fully elucidated. It has been demonstrated that VPA, at therapeutically relevant concentrations, increases AP-1 DNA binding activity in cultured cells in vitro. These findings raise the possibility that VPA may produce its mood-stabilizing effects by regulating the expression of subsets of genes via its effects on the AP-1 family of transcription factors. To determine if VPA does, in fact, enhance AP-1 mediated gene expression, the effects of VPA on the expression of a luciferase reporter gene were studied in transiently transfected rat C6 glioma and human SH-SY5Y neuroblastoma cells using the pGL2-control vector. The luciferase gene in the vector is driven by an SV40 promoter which contains well characterized AP-1 sites. VPA produced a greater than doubling of luciferase activity in a time- and concentration-dependent manner in both cell lines. Furthermore, mutations of the AP-1 sites in the SV40 promoter markedly attenuated the VPA-induced increases in luciferase activity. These effects of VPA on AP-1 mediated gene expression are very similar to the effects observed with lithium, and suggest that the temporal regulation of AP-1 mediated gene expression in critical neuronal circuits may play a role in the long-term therapeutic efficacy of these agents.

Lithium stimulates gene expression through the AP-1 transcription factor pathway

Lithium, a monovalent cation, is the mainstay in the treatment of manic-depressive (MDI) illness, but despite extensive research, its mechanism of action remains to be elucidated. Since lithium requires chronic administration for therapeutic efficacy, and because its beneficial effects last well beyond its discontinuation, it has been postulated that lithium may exert major effects at the genomic level. In the present study we found that lithium, at therapeutically relevant concentrations, increases AP-1 DNA binding activity in human SH-SY5Y cells and rat C6 glioma cells. Additionally, in both SY5Y and C6 cells transiently transfected with a reporter gene vector driven by an SV40 promoter, lithium increased the activity of the reporter gene in a time- and concentration-dependent manner. Furthermore, mutations in the AP-1 sites of the reporter gene promoter significantly attenuated lithium's effects. These data indicate that lithium stimulates gene expression through the AP-1 transcription factor pathway, effects which may play a role in its long-term mood-stabilizing effects.

Lithium increases tyrosine hydroxylase levels both in vivo and in vitro

Lithium, a simple monovalent cation, is the mainstay in the treatment of manic-depressive illness, but despite extensive research, its mechanism of action remains to be elucidated. Because lithium requires chronic administration for therapeutic efficacy and because its beneficial effects last well beyond its discontinuation, it has been postulated that lithium may exert major effects at the genomic level. We have previously shown that lithium, at therapeutically relevant concentrations, increases gene expression through the activator protein-1 (AP-1) transcription factor pathway in vitro. In the present study, we have sought to determine if lithium also increases the expression of endogenous genes known to be regulated by AP-1 and have therefore investigated the effects of lithium on tyrosine hydroxylase (TH) levels. Male Wistar rats were treated with LiCl for 9 days (subacute) or 4 weeks (chronic), and TH levels were measured in frontal cortex, hippocampus, and striatum using immunoblotting. Chronic (but not subacute) lithium treatment resulted in significant increases in TH levels in rat frontal cortex, hippocampus, and striatum. Lithium (1 mM) also increased TH levels in human SH-SY5Y neuroblastoma cells in vitro, indicating that lithium increases TH levels in both rodent and human tissues, likely via a direct cellular effect. These effects are compatible with (but likely not exclusively due to) an effect on the DNA binding of the 12-O-tetradecanoylphorbol 13-acetate response element to the AP-1 family of transcription factors.