Histone renegades: Unusual H2A histone variants in plants and animals.

H2A variants are histones that carry out specialized nucleosome function during the eukaryote genome packaging. Most genes encoding H2A histone variants arose in the distant past, and have highly conserved domains and structures. Yet, novel H2A variants have continued to arise throughout the radiation of eukaryotes and disturbed the apparent tranquility of nucleosomes. These species-specific H2A variants contributed to the functional diversification of nucleosomes through changes in both their structure and expression patterns. In this short review, we discuss the evolutionary trajectories of these histone renegades in plants and animal genomes.

CRISPR/Cas9 and FLP-FRT mediated regulatory dissection of the BX-C of Drosophila melanogaster.

The homeotic genes or Hox define the anterior-posterior (AP) body axis formation in bilaterians and are often present on the chromosome in an order collinear to their function across the AP axis. However, there are many cases wherein the Hox are not collinear, but their expression pattern is conserved across the AP axis. The expression pattern of Hox is attributed to the cis-regulatory modules (CRMs) consisting of enhancers, initiators, or repressor elements that regulate the genes in a segment-specific manner. In the Drosophila melanogaster Hox complex, the bithorax complex (BX-C) and even the CRMs are organized in an order that is collinear to their function in the thoracic and abdominal segments. In the present study, the regulatorily inert regions were targeted using CRISPR/Cas9 to generate a series of transgenic lines with the insertion of FRT sequences. These FRT lines are repurposed to shuffle the CRMs associated with Abd-B to generate modular deletion, duplication, or inversion of multiple CRMs. The rearrangements yielded entirely novel phenotypes in the fly suggesting the requirement of such complex manipulations to address the significance of higher order arrangement of the CRMs. The functional map and the transgenic flies generated in this study are important resources to decipher the collective ability of multiple regulatory elements in the eukaryotic genome to function as complex modules.

Preclinical Evaluation of HER2-Targeting DARPin G3: Impact of Albumin-Binding Domain (ABD) Fusion.

Designed ankyrin repeat protein (DARPin) G3 is an engineered scaffold protein. This small (14.5 kDa) targeting protein binds with high affinity to human epidermal growth factor receptor 2 (HER2). HER2 is overexpressed in several cancers. The use of the DARPin G3 for radionuclide therapy is complicated by its high renal reabsorption after clearance via the glomeruli. We tested the hypothesis that a fusion of the DARPin G3 with an albumin-binding domain (ABD) would prevent rapid renal excretion and high renal reabsorption resulting in better tumour targeting. Two fusion proteins were produced, one with the ABD at the C-terminus (G3-ABD) and another at the N-terminus (ABD-G3). Both variants were labelled with 177Lu. The binding properties of the novel constructs were evaluated in vitro and their biodistribution was compared in mice with implanted human HER2-expressing tumours. Fusion with the ABD increased the retention time of both constructs in blood compared with the non-ABD-fused control. The effect of fusion with the ABD depended strongly on the order of the domains in the constructs, resulting in appreciably better targeting properties of [177Lu]Lu-G3-ABD. Our data suggest that the order of domains is critical for the design of targeting constructs based on scaffold proteins.

Transcriptional Readthrough Interrupts Boundary Function in Drosophila.

In higher eukaryotes, distance enhancer-promoter interactions are organized by topologically associated domains, tethering elements, and chromatin insulators/boundaries. While insulators/boundaries play a central role in chromosome organization, the mechanisms regulating their functions are largely unknown. In the studies reported here, we have taken advantage of the well-characterized Drosophila bithorax complex (BX-C) to study one potential mechanism for controlling boundary function. The regulatory domains of BX-C are flanked by boundaries, which block crosstalk with their neighboring domains and also support long-distance interactions between the regulatory domains and their target gene. As many lncRNAs have been found in BX-C, we asked whether readthrough transcription (RT) can impact boundary function. For this purpose, we took advantage of two BX-C boundary replacement platforms, Fab-7attP50 and F2attP, in which the Fab-7 and Fub boundaries, respectively, are deleted and replaced with an attP site. We introduced boundary elements, promoters, and polyadenylation signals arranged in different combinations and then assayed for boundary function. Our results show that RT can interfere with boundary activity. Since lncRNAs represent a significant fraction of Pol II transcripts in multicellular eukaryotes, it is therefore possible that RT may be a widely used mechanism to alter boundary function and regulation of gene expression.

Mechanisms of Interaction between Enhancers and Promoters in Three Drosophila Model Systems.

In higher eukaryotes, the regulation of developmental gene expression is determined by enhancers, which are often located at a large distance from the promoters they regulate. Therefore, the architecture of chromosomes and the mechanisms that determine the functional interaction between enhancers and promoters are of decisive importance in the development of organisms. Mammals and the model animal Drosophila have homologous key architectural proteins and similar mechanisms in the organization of chromosome architecture. This review describes the current progress in understanding the mechanisms of the formation and regulation of long-range interactions between enhancers and promoters at three well-studied key regulatory loci in Drosophila.

The histone chaperone Spt6 is required for normal recruitment of the capping enzyme Abd1 to transcribed regions.

The histone chaperone Spt6 is involved in promoting elongation of RNA polymerase II (RNAPII), maintaining chromatin structure, regulating cotranscriptional histone modifications, and controlling mRNA processing. These diverse functions of Spt6 are partly mediated through its interactions with RNAPII and other factors in the transcription elongation complex. In this study, we used mass spectrometry to characterize the differences in RNAPII-interacting factors between wildtype cells and those depleted for Spt6, leading to the identification of proteins that depend on Spt6 for their interaction with RNAPII. The altered association of some of these factors could be attributed to changes in steady-state protein levels. However, Abd1, the mRNA cap methyltransferase, had decreased association with RNAPII after Spt6 depletion despite unchanged Abd1 protein levels, showing a requirement for Spt6 in mediating the Abd1-RNAPII interaction. Genome-wide studies showed that Spt6 is required for maintaining the level of Abd1 over transcribed regions, as well as the level of Spt5, another protein known to recruit Abd1 to chromatin. Abd1 levels were particularly decreased at the 5' ends of genes after Spt6 depletion, suggesting a greater need for Spt6 in Abd1 recruitment over these regions. Together, our results show that Spt6 is important in regulating the composition of the transcription elongation complex and reveal a previously unknown function for Spt6 in the recruitment of Abd1.

Novel VHH-Based Tracers with Variable Plasma Half-Lives for Imaging of CAIX-Expressing Hypoxic Tumor Cells.

Hypoxic areas are present in the majority of solid tumors, and hypoxia is associated with resistance to therapies and poor outcomes. A transmembrane protein that is upregulated by tumor cells that have adapted to hypoxic conditions is carbonic anhydrase IX (CAIX). Therefore, noninvasive imaging of CAIX could be of prognostic value, and it could steer treatment strategies. The aim of this study was to compare variants of CAIX-binding VHH B9, with and without a C-terminal albumin-binding domain with varying affinity (ABDlow and ABDhigh), for SPECT imaging of CAIX expression. The binding affinity and internalization of the various B9-variants were analyzed using SK-RC-52 cells. Biodistribution studies were performed in mice with subcutaneous SCCNij153 human head and neck cancer xenografts. Tracer uptake was determined by ex vivo radioactivity counting and visualized by SPECT/CT imaging. Furthermore, autoradiography images of tumor sections were spatially correlated with CAIX immunohistochemistry. B9-variants demonstrated a similar moderate affinity for CAIX in vitro. Maximal tumor uptake and acceptable tumor-to-blood ratios were found in the SCCNij153 model at 4 h post injection for [111In]In-DTPA-B9 (0.51 ± 0.08%ID/g and 8.1 ± 0.85, respectively), 24 h post injection for [111In]In-DTPA-B9-ABDlow (2.39 ± 0.44%ID/g and 3.66 ± 0.81, respectively) and at 72 h post injection for [111In]In-DTPA-B9-ABDhigh (8.7 ± 1.34%ID/g and 2.43 ± 0.15, respectively). An excess of unlabeled monoclonal anti-CAIX antibody efficiently inhibited tumor uptake of [111In]In-DTPA-B9, while only a partial reduction of [111In]In-DTPA-B9-ABDlow and [111In]In-DTPA-B9-ABDhigh uptake was found. Immunohistochemistry and autoradiography images showed colocalization of all B9-variants with CAIX expression; however, [111In]In-DTPA-B9-ABDlow and [111In]In-DTPA-B9-ABDhigh also accumulated in non-CAIX expressing regions. Tumor uptake of [111In]In-DTPA-B9-ABDlow and [111In]In-DTPA-B9-ABDhigh, but not of [111In]In-DTPA-B9, could be visualized with SPECT/CT imaging. In conclusion, [111In]In-DTPA-B9 has a high affinity to CAIX and shows specific targeting to CAIX in head and neck cancer xenografts. The addition of ABD prolonged plasma half-life, increased tumor uptake, and enabled SPECT/CT imaging. This uptake was, however, partly CAIX- independent, precluding the ABD-tracers for use in hypoxia quantification in this tumor type.

Synthesis and biological evaluation of glucagon-like peptide-1 analogs with the C-terminal helix 3 of albumin-binding domain 3.

Based on peptide 6 (Ser8-GLP-1 [7-35]-GVKALIDEILAA-NH2; GVKALI-DEILAA is the C-terminal helix 3 of albumin-binding domain 3 of protein G from bacterial Streptococcal G strain 148 [G148-ABD3]), a series of its analogs (compounds 0-VI: Aib8-GLP-1 [7-35]-linkers-GVKALIDEILAA-NH2) were designed and synthesized using microwave-assisted solid-phase synthesis. First, to monitor the reaction process and reduce potential risks, the synthesis process of compounds 0-VI was divided into three stages. Next, to explore the effect of these linkers on their albumin-binding rates, albumin-binding assays were performed. Finally, to evaluate their biological activities in vitro and in vivo, receptor potency, surface plasmon resonance (SPR), weight-loss, and glucose-lowering assays were carried out. These results indicated the linkers of different polarities between Aib8-GLP-1 (7-35) and the C-terminal helix 3 of ABD3 can significantly affect the albumin-binding rate of the C-terminal helix 3 of ABD3. And compound IV had the highest albumin-binding rates, weight-loss, and glucose-lowering effects among them.

A homeotic shift late in development drives mimetic color variation in a bumble bee.

Natural phenotypic radiations, with their high diversity and convergence, are well-suited for informing how genomic changes translate to natural phenotypic variation. New genomic tools enable discovery in such traditionally nonmodel systems. Here, we characterize the genomic basis of color pattern variation in bumble bees (Hymenoptera, Apidae, Bombus), a group that has undergone extensive convergence of setal color patterns as a result of Müllerian mimicry. In western North America, multiple species converge on local mimicry patterns through parallel shifts of midabdominal segments from red to black. Using genome-wide association, we establish that a cis-regulatory locus between the abdominal fate-determining Hox genes, abd-A and Abd-B, controls the red-black color switch in a western species, Bombus melanopygus Gene expression analysis reveals distinct shifts in Abd-B aligned with the duration of setal pigmentation at the pupal-adult transition. This results in atypical anterior Abd-B expression, a late developmental homeotic shift. Changing expression of Hox genes can have widespread effects, given their important role across segmental phenotypes; however, the late timing reduces this pleiotropy, making Hox genes suitable targets. Analysis of this locus across mimics and relatives reveals that other species follow independent genetic routes to obtain the same phenotypes.

A Novel Soluble ACE2 Variant with Prolonged Duration of Action Neutralizes SARS-CoV-2 Infection in Human Kidney Organoids.

BACKGROUND: There is an urgent need for approaches to prevent and treat SARS-CoV-2 infection. Administration of soluble ACE2 protein acting as a decoy to bind to SARS-CoV-2 should limit viral uptake mediated by binding to membrane-bound full-length ACE2, and further therapeutic benefit should result from ensuring enzymatic ACE2 activity to affected organs in patients with COVID-19. METHODS: A short variant of human soluble ACE2 protein consisting of 618 amino acids (hACE2 1-618) was generated and fused with an albumin binding domain (ABD) using an artificial gene encoding ABDCon, with improved albumin binding affinity. Human kidney organoids were used for infectivity studies of SARS-CoV-2 in a BSL-3 facility to examine the neutralizing effect of these novel ACE2 variants. RESULTS: Whereas plasma ACE2 activity of the naked ACE2 1-618 and ACE2 1-740 lasted about 8 hours, the ACE2 1-618-ABD resulted in substantial activity at 96 hours, and it was still biologically active 3 days after injection. Human kidney organoids express ACE2 and TMPRSS2, and when infected with SARS-CoV-2, our modified long-acting ACE2 variant neutralized infection. CONCLUSIONS: This novel ACE2 1-618-ABD can neutralize SARS-CoV-2 infectivity in human kidney organoids, and its prolonged duration of action should ensure improved efficacy to prevent viral escape and dosing convenience.

Genetic and Chemical Diversity of Commercial Japanese Valerian.

In order to investigate the relationship between the chemical composition of essential oils and haplotypes of the psbA-trnH intergenic spacer region of chloroplast DNA (psbA-trnH) in Valerianae Fauriei Radix (Japanese Valerian; JV), we analyzed the DNA sequence and GC-MS metabolome of JV from Japanese markets and of herbal specimens from related species. DNA analysis revealed that JV products from Japan consisted of three haplotypes, namely AH-1, -2 and -5 reported in our previous study. The GC-MS metabolome revealed five chemotypes (J1, J2, C, K and O), of which J1, J2 and C were detected in the JV products from Japan. Chemotypes J1 and J2, with kessyl glycol diacetate (KGD) as the main volatile component, were found in the products of Japanese origin whereas chemotype C, with 1-O-acetyl-2,10-bisaboladiene-1,6-diol (ABD), was found in the products of Chinese and Korean origin. The haplotypes were correlated with the chemotypes: haplotype AH-1 for chemotype J1, AH-2 for chemotype J2 and AH-5 for chemotype C, suggesting that the chemical diversity of JV is not attributed to the environmental factors rather to the genetic factors. Since KGD and ABD were reported to have sedative effects and nerve growth factor (NGF)-potentiating effects, respectively, understanding the chemotypes and selecting an appropriate one would be important for the application of JV. The psbA-trnH haplotypes could be useful DNA markers for the quality control and standardization of JV.

Fragments of the Fab-3 and Fab-4 Boundaries of the Drosophila melanogaster Bithorax Complex That Include CTCF Sites Are not Effective Insulators.

The segment-specific regulatory domains of the Bithorax complex (BX-C), which consists of three homeotic genes Ubx, abd-A and Abd-B, are separated by boundaries that function as insulators. Most of the boundaries contain binding sites for the architectural protein CTCF, which is conserved for higher eukaryotes. As was shown previously, the CTCF sites determine the insulator activity of the boundaries of the Abd-B regulatory region. In this study, it was shown that fragments of the Fab-3 and Fab-4 boundaries of the abd-A regulatory region, containing CTCF binding sites, are not effective insulators.

Small Bispecific Affinity Proteins for Simultaneous Target Binding and Albumin-Associated Half-Life Extension.

Albumin-binding fusion partners are frequently used as a means for the in vivo half-life extension of small therapeutic molecules that would normally be cleared very rapidly from circulation. However, in applications where small size is key, fusion to an additional molecule can be disadvantageous. Albumin-derived affinity proteins (ADAPTs) are a new type of scaffold proteins based on one of the albumin-binding domains of streptococcal protein G, with engineered binding specificities against numerous targets. Here, we engineered this scaffold further and showed that this domain, as small as 6 kDa, can harbor two distinct binding surfaces and utilize them to interact with two targets simultaneously. These novel ADAPTs were developed to possess affinity toward both serum albumin as well as another clinically relevant target, thus circumventing the need for an albumin-binding fusion partner. To accomplish this, we designed a phage display library and used it to successfully select for single-domain bispecific binders toward a panel of targets: TNFα, prostate-specific antigen (PSA), C-reactive protein (CRP), renin, angiogenin, myeloid-derived growth factor (MYDGF), and insulin. Apart from successfully identifying bispecific binders for all targets, we also demonstrated the formation of the ternary complex consisting of the ADAPT together with albumin and each of the five targets, TNFα, PSA, angiogenin, MYDGF, and insulin. This simultaneous binding of albumin and other targets presents an opportunity to combine the advantages of small molecules with those of larger ones allowing for lower cost of goods and noninvasive administration routes while still maintaining a sufficient in vivo half-life.

Cerebral oxygenation monitoring of ex-preterm infants during the infant car seat challenge test.

The American Academy of Pediatrics and until recently the Canadian Paediatric Society recommend preterm infants undergo an Infant Car Seat Challenge test prior to discharge to rule out systemic oxygen desaturation when placed at a 45-degree angle in a car seat. Near-infrared spectroscopy (NIRS) provides objective measurements of the impact of systemic oxygen (SO2) desaturation, bradycardia, or both on cerebral regional oxygen saturation (rSO2). OBJECTIVE: To characterize baseline cerebral rSO2 during a car seat trial in preterm infants ready for discharge. DESIGN/METHODS: A prospective observational study was performed in 20 infants (32 ± 5 weeks [mean] at a postmenstrual age 37 ± 6 weeks [mean]). Cerebral rSO2 was continuously monitored by placing a NIRS transducer on head during Infant Car Seat Challenge (ICSC). Failure of an ICSC was defined as two SO2 desaturation events below 85% for more than 20 seconds or one event below 80% for 10 seconds. RESULTS: The lowest SO2 was 70% with a lowest NIRS recording of 68%. Three infants failed their ICSC, with the lowest rSO2 in these three infants being 68%, above the lowest acceptable limit of 55%. Heart rate but not SO2 appears to influence rSO2 over the range of cerebral oxygenation seen. CONCLUSIONS: Baseline cerebral rSO2 during ICSC oscillates between 68 and 90%. There were no episodes of significant cerebral oxygen desaturation in studied infants regardless of whether they passed or failed the ICSC. We postulate that former preterm infants are capable through cerebral autoregulation, of maintaining adequate cerebral blood flow in the presence of either systemic oxygen desaturation or bradycardia when they are otherwise ready for discharge.

Pharmacological targeting of RAS: Recent success with direct inhibitors.

RAS has long been viewed as undruggable due to its lack of deep pockets for binding of small molecule inhibitors. However, recent successes in the development of direct RAS inhibitors suggest that the goal of pharmacological inhibition of RAS in patients may soon be realized. This review will discuss the role of RAS in cancer, the approaches used to develop direct RAS inhibitors, and highlight recent successes in the development of novel RAS inhibitory compounds that target different aspects of RAS biochemistry. In particular, this review will discuss the different properties of RAS that have been targeted by various inhibitors including membrane localization, the different activation states of RAS, effector binding, and nucleotide exchange. In addition, this review will highlight the recent success with mutation-specific inhibitors that exploit the unique biochemistry of the RAS(G12C) mutant. Although this mutation in KRAS accounts for 11% of all KRAS mutations in cancer, it is the most prominent KRAS mutant in lung cancer suggesting that G12C-specific inhibitors may provide a new approach for treating the subset of lung cancer patients harboring this mutant allele. Finally, this review will discuss the involvement of dimerization in RAS function and highlight new approaches to inhibit RAS by specifically interfering with RAS:RAS interaction.

Ketamine for Rapid Sedation of Agitated Patients in the Prehospital and Emergency Department Settings: A Systematic Review and Proportional Meta-Analysis.

BACKGROUND: Rapid tranquilization of agitated patients can prevent injuries and expedite care. Whereas antipsychotics and benzodiazepines are commonly used for this purpose, ketamine has been suggested as an alternative. OBJECTIVE: The aim of this systematic review is to determine the safety and effectiveness of ketamine to sedate prehospital and emergency department (ED) patients with undifferentiated agitation. METHODS: Studies and case series of patients receiving ketamine for agitation were included. Studies were excluded if ketamine was used for analgesia, procedural sedation, asthma, or induction. Information sources included traditional and gray literature. RESULTS: The initial search yielded 1176 results from 14 databases. After review of titles and abstracts, 32 studies were reviewed and 18 were included in the analysis, representing 650 patient encounters. The mean dose of ketamine was 315 mg (SD 52) given intramuscularly, with adequate sedation achieved in 7.2 min (SD 6.2, range 2-500). Intubation occurred in 30.5% of patients (95% confidence interval [CI] 27.0-34.1%). In the majority of those patients, ketamine was administered by paramedics during ground transport and the patient was intubated on ED arrival. When ketamine was administered in the ED, the intubation rate was 1.8% (95% CI 0.0-4.4%); in air medical transport, the rate was 4.9% (95% CI 0.0-10.3%). Other reported side effects included: vomiting, 5.2% (2.3-8.1%); hypertension, 12.1% (5.7-18.6%); emergence reactions, 3.5% (1.4-5.6%); transient hypoxia, 1.8% (0.1-3.6%) and laryngospasm, 1.3% (0.3-2.3%). CONCLUSIONS: Ketamine provides rapid sedation for undifferentiated agitated patients and is associated with higher intubation rates when used by ground Emergency Medical Services paramedics, compared with ED or air medical transport patients. Other side effects are common but usually self-limiting.

Synthesis and Pharmacological Evaluation of Novel Silodosin-Based Arylsulfonamide Derivatives as α1A/α1D-Adrenergic Receptor Antagonist with Potential Uroselective Profile.

Benign prostatic hyperplasia (BPH) is the most common male clinical problem impacting the quality of life of older men. Clinical studies have indicated that the inhibition of α1A-/α1D adrenoceptors might offer effective therapy in lower urinary tract symptoms. Herein, a limited series of arylsulfonamide derivatives of (aryloxy)ethyl alicyclic amines was designed, synthesized, and biologically evaluated as potent α1-adrenoceptor antagonists with uroselective profile. Among them, compound 9 (3-chloro-2-fluoro-N-([1-(2-(2-(2,2,2-trifluoroethoxy)phenoxy]ethyl)piperidin-4-yl)methyl)benzenesulfonamide) behaved as an α1A-/α1D-adrenoceptor antagonist (Ki(α1) = 50 nM, EC50(α1A) = 0.8 nM, EC50(α1D) = 1.1 nM), displayed selectivity over α2-adrenoceptors (Ki(α2) = 858 nM), and a 5-fold functional preference over the α1B subtype. Compound 9 showed adequate metabolic stability in rat-liver microsome assay similar to the reference drug tamsulosin (Clint = 67 and 41 µL/min/mg, respectively). Compound 9 did not decrease systolic and diastolic blood pressure in normotensive anesthetized rats in the dose of 2 mg/kg, i.v. These data support development of uroselective agents in the group of arylsulfonamides of alicyclic amines with potential efficacy in the treatment of lower urinary tract symptoms associated to benign prostatic hyperplasia.

An engineered affibody molecule with pH-dependent binding to FcRn mediates extended circulatory half-life of a fusion protein.

Proteins endocytosed from serum are degraded in the lysosomes. However, serum albumin (SA) and IgG, through its Fc part, bind to the neonatal Fc receptor (FcRn) at low pH in the endosome after endocytosis, and are transported back to the cellular surface, where they are released into the bloodstream, resulting in an extended serum circulation time. Association with Fc or SA has been used to prolong the in vivo half-life of biopharmaceuticals, using the interaction with FcRn to improve treatment regimens. This has been achieved either directly, by fusion or conjugation to Fc or SA, or indirectly, using SA-binding proteins. The present work takes this principle one step further, presenting small affinity proteins that bind directly to FcRn, mediating extension of the serum half-life of fused biomolecules. Phage display technology was used to select affibody molecules that can bind to FcRn in the pH-dependent manner required for rescue by FcRn. The biophysical and binding properties were characterized in vitro, and the affibody molecules were found to bind to FcRn more strongly at low pH than at neutral pH. Attachment of the affibody molecules to a recombinant protein, already engineered for increased half-life, resulted in a nearly threefold longer half-life in mice. These tags should have general use as fusion partners to biopharmaceuticals to extend their half-lives in vivo.

Quantification of thiols and disulfides.

BACKGROUND: Disulfide bond formation is a key posttranslational modification, with implications for structure, function and stability of numerous proteins. While disulfide bond formation is a necessary and essential process for many proteins, it is deleterious and disruptive for others. Cells go to great lengths to regulate thiol-disulfide bond homeostasis, typically with several, apparently redundant, systems working in parallel. Dissecting the extent of oxidation and reduction of disulfides is an ongoing challenge due, in part, to the facility of thiol/disulfide exchange reactions. SCOPE OF REVIEW: In the present account, we briefly survey the toolbox available to the experimentalist for the chemical determination of thiols and disulfides. We have chosen to focus on the key chemical aspects of current methodology, together with identifying potential difficulties inherent in their experimental implementation. MAJOR CONCLUSIONS: While many reagents have been described for the measurement and manipulation of the redox status of thiols and disulfides, a number of these methods remain underutilized. The ability to effectively quantify changes in redox conditions in living cells presents a continuing challenge. GENERAL SIGNIFICANCE: Many unresolved questions in the metabolic interconversion of thiols and disulfides remain. For example, while pool sizes of redox pairs and their intracellular distribution are being uncovered, very little is known about the flux in thiol-disulfide exchange pathways. New tools are needed to address this important aspect of cellular metabolism. This article is part of a Special Issue entitled Current methods to study reactive oxygen species - pros and cons and biophysics of membrane proteins. Guest Editor: Christine Winterbourn.

Spectrins: a structural platform for stabilization and activation of membrane channels, receptors and transporters.

This review focuses on structure and functions of spectrin as a major component of the membrane skeleton. Recent advances on spectrin function as an interface for signal transduction mediation and a number of data concerning interaction of spectrin with membrane channels, adhesion molecules, receptors and transporters draw a picture of multifaceted protein. Here, we attempted to show the current depiction of multitask role of spectrin in cell physiology. This article is part of a Special Issue entitled: Reciprocal influences between cell cytoskeleton and membrane channels, receptors and transporters. Guest Editor: Jean Claude Hervé.