Beta cell-specific PAK1 enrichment ameliorates diet-induced glucose intolerance in mice by promoting insulin biogenesis and minimising beta cell apoptosis.

AIMS/HYPOTHESIS: p21 (CDC42/RAC1) activated kinase 1 (PAK1) is depleted in type 2 diabetic human islets compared with non-diabetic human islets, and acute PAK1 restoration in the islets can restore insulin secretory function ex vivo. We hypothesised that beta cell-specific PAK1 enrichment in vivo can mitigate high-fat-diet (HFD)-induced glucose intolerance by increasing the functional beta cell mass. METHODS: Human islets expressing exogenous PAK1 specifically in beta cells were used for bulk RNA-seq. Human EndoC-ßH1 cells overexpressing myc-tagged PAK1 were used for chromatin immunoprecipitation (ChIP) and ChIP-sequencing (ChIP-seq). Novel doxycycline-inducible beta cell-specific PAK1-expressing (ißPAK1-Tg) mice were fed a 45% HFD pre-induction for 3 weeks and for a further 3 weeks with or without doxycycline induction. These HFD-fed mice were evaluated for GTT, ITT, 6 h fasting plasma insulin and blood glucose, body composition, islet insulin content and apoptosis. RESULTS: Beta cell-specific PAK1 enrichment in type 2 diabetes human islets resulted in decreased beta cell apoptosis and increased insulin content. RNA-seq showed an upregulation of INS gene transcription by PAK1. Using clonal human beta cells, we found that PAK1 protein was localised in the cytoplasm and the nucleus. ChIP studies revealed that nuclear PAK1 enhanced pancreatic and duodenal homeobox1 (PDX1) and neuronal differentiation 1 (NEUROD1) binding to the INS promoter in a glucose-responsive manner. Importantly, the ißPAK1-Tg mice, when challenged with HFD and doxycycline induction displayed enhanced glucose tolerance, increased islet insulin content and reduced beta cell apoptosis when compared with ißPAK1-Tg mice without doxycycline induction. CONCLUSIONS/INTERPRETATION: PAK1 plays an unforeseen and beneficial role in beta cells by promoting insulin biogenesis via enhancing the expression of PDX1, NEUROD1 and INS, along with anti-apoptotic effects, that culminate in increased insulin content and beta cell mass in vivo and ameliorate diet-induced glucose intolerance. DATA AVAILABILITY: The raw and processed RNA-seq data and ChIP-seq data, which has been made publicly available at Gene Expression Omnibus (GEO) at https://www.ncbi.nlm.nih.gov/geo/ , can be accessed in GSE239382.

Podophyllic Aldehyde, a Podophyllotoxin Derivate, Elicits Different Cell Cycle Profiles Depending on the Tumor Cell Line: A Systematic Proteomic Analysis.

When new antitumor therapy drugs are discovered, it is essential to address new target molecules from the point of view of chemical structure and to carry out efficient and systematic evaluation. In the case of natural products and derived compounds, it is of special importance to investigate chemomodulation to further explore antitumoral pharmacological activities. In this work, the compound podophyllic aldehyde, a cyclolignan derived from the chemomodulation of the natural product podophyllotoxin, has been evaluated for its viability, influence on the cell cycle, and effects on intracellular signaling. We used functional proteomics characterization for the evaluation. Compared with the FDA-approved drug etoposide (another podophyllotoxin derivative), we found interesting results regarding the cytotoxicity of podophyllic aldehyde. In addition, we were able to observe the effect of mitotic arrest in the treated cells. The use of podophyllic aldehyde resulted in increased cytotoxicity in solid tumor cell lines, compared to etoposide, and blocked the cycle more successfully than etoposide. High-throughput analysis of the deregulated proteins revealed a selective antimitotic mechanism of action of podophyllic aldehyde in the HT-29 cell line, in contrast with other solid and hematological tumor lines. Also, the apoptotic profile of podophyllic aldehyde was deciphered. The cell death mechanism is activated independently of the cell cycle profile. The results of these targeted analyses have also shown a significant response to the signaling of kinases, key proteins involved in signaling cascades for cell proliferation or metastasis. Thanks to this comprehensive analysis of podophyllic aldehyde, remarkable cytotoxic, antimitotic, and other antitumoral features have been discovered that will repurpose this compound for further chemical transformations and antitumoral analysis.

Cytotoxic Cyclolignans Obtained by the Enlargement of the Cyclolignan Skeleton of Podophyllic Aldehyde, a Selective Podophyllotoxin-Derived Cyclolignan.

Podophyllotoxin, a cyclolignan natural product, has been the object of extensive chemomodulation to obtain better chemotherapeutic agents. Among the obtained podophyllotoxin derivatives, podophyllic aldehyde showed very interesting potency and selectivity against several tumoral cell lines, so it became our lead compound for further modifications, as described in this work, oriented toward the enlargement of the cyclolignan skeleton. Thus, modifications performed at the aldehyde function included nucleophilic addition reactions and the incorporation of the aldehyde carbon into several five-membered rings, such as thiazolidinones and benzo-fused azoles. The synthesized derivatives were evaluated against several types of cancer cells, and although some compounds were cytotoxic at the nanomolar range, most of them were less potent and less selective than the parent compound podophyllic aldehyde, with the most potent being those having the lactone ring of podophyllotoxin. In silico ADME evaluation predicted good druggability for most of them. The results indicate that the γ-lactone ring is important for potency, while the α,ß-unsaturated aldehyde is necessary to induce selectivity in these cyclolignans.

Chemical and Bioactive Properties of Red Rice with Potential Pharmaceutical Use.

Red rice has been proposed as a super-food. Accordingly, the nutritional properties (AOAC), as well as its chemical composition, including sugars (HPLC-RI), organic acids (UFLC-PDA), tocopherols (HPLD-FD), and phenolic compounds (LC-DAD-ESI/MSn), together with the main bioactive properties (antioxidant, cytotoxic, antiproliferative, and antibacterial activities), were evaluated to access its nutritional benefits and health improvement potential. The most abundant macronutrients found were carbohydrates (87.2 g/100 g dw), proceeded by proteins (9.1 g/100 g dw), fat (2.6 g/100 g dw), and ash (1.1 g/100 g dw). Sucrose and raffinose were the only detected sugars, with sucrose presenting the maximum concentration (0.74 g/100 g dw). MUFAs and PUFAs were the predominant fatty acids (40.7% and 31%, respectively). Among the two detected tocopherol isoforms, γ-tocopherol (0.67 mg/100 g dw) predominated over α-tocopherol. The phenolic compounds profile, majorly composed of flavan-3-ols, should be associated with the detected bioactivities, which may provide biological benefits to human health beyond the primary nutritional effect. Overall, the bioactive potential of red rice was comprehensively accessed.

Characterization of a neutralizing anti-human galectin-1 monoclonal antibody with angioregulatory and immunomodulatory activities.

Galectins, a family of highly conserved ß-galactoside-binding proteins, control tumor progression by modulating different hallmarks of cancer. Galectin-1 (Gal-1), a proto-type member of this family, plays essential roles in tumor angiogenesis and immunosuppression by cross-linking glycosylated receptors on the surface of endothelial and immune cells. Targeted disruption of Gal-1 suppresses tumor growth by counteracting aberrant angiogenesis and reinforcing antitumor immunity in several experimental settings. Given the multiple therapeutic benefits associated with Gal-1 blockade, several Gal-1 inhibitors, including glycan-based competitors, antagonistic peptides, aptamers and neutralizing monoclonal antibodies, have been designed and evaluated in pre-clinical tumor models. Here we report the biochemical and functional characterization of a newly developed neutralizing anti-human Gal-1 monoclonal antibody (Gal-1-mAb3), which specifically recognizes a unique epitope in Gal-1 protein and exerts both angioregulatory and immunomodulatory activities. Blockade of Gal-1 function using Gal-1-mAb3, might be relevant not only in cancer but also in other pathologic conditions characterized by aberrant angiogenesis and uncontrolled immunosuppression.

Super-resolution microscopy reveals how histone tail acetylation affects DNA compaction within nucleosomes in vivo.

Chromatin organization is crucial for regulating gene expression. Previously, we showed that nucleosomes form groups, termed clutches. Clutch size correlated with the pluripotency grade of mouse embryonic stem cells and human induced pluripotent stem cells. Recently, it was also shown that regions of the chromatin containing activating epigenetic marks were composed of small and dispersed chromatin nanodomains with lower DNA density compared to the larger silenced domains. Overall, these results suggest that clutch size may regulate DNA packing density and gene activity. To directly test this model, we carried out 3D, two-color super-resolution microscopy of histones and DNA with and without increased histone tail acetylation. Our results showed that lower percentage of DNA was associated with nucleosome clutches in hyperacetylated cells. We further showed that the radius and compaction level of clutch-associated DNA decreased in hyperacetylated cells, especially in regions containing several neighboring clutches. Importantly, this change was independent of clutch size but dependent on the acetylation state of the clutch. Our results directly link the epigenetic state of nucleosome clutches to their DNA packing density. Our results further provide in vivo support to previous in vitro models that showed a disruption of nucleosome-DNA interactions upon hyperacetylation.

Excitation-multiplexed multicolor superresolution imaging with fm-STORM and fm-DNA-PAINT.

Recent advancements in single-molecule-based superresolution microscopy have made it possible to visualize biological structures with unprecedented spatial resolution. Determining the spatial coorganization of these structures within cells under physiological and pathological conditions is an important biological goal. This goal has been stymied by the current limitations of carrying out superresolution microscopy in multiple colors. Here, we develop an approach for simultaneous multicolor superresolution imaging which relies solely on fluorophore excitation, rather than fluorescence emission properties. By modulating the intensity of the excitation lasers at different frequencies, we show that the color channel can be determined based on the fluorophore's response to the modulated excitation. We use this frequency multiplexing to reduce the image acquisition time of multicolor superresolution DNA-PAINT while maintaining all its advantages: minimal color cross-talk, minimal photobleaching, maximal signal throughput, ability to maintain the fluorophore density per imaged color, and ability to use the full camera field of view. We refer to this imaging modality as "frequency multiplexed DNA-PAINT," or fm-DNA-PAINT for short. We also show that frequency multiplexing is fully compatible with STORM superresolution imaging, which we term fm-STORM. Unlike fm-DNA-PAINT, fm-STORM is prone to color cross-talk. To overcome this caveat, we further develop a machine-learning algorithm to correct for color cross-talk with more than 95% accuracy, without the need for prior information about the imaged structure.

New Antineoplastic Naphthohydroquinones Attached to Labdane and Rearranged Diterpene Skeletons.

Terpenylquinones are mixed biogenesis primary or secondary metabolites widespread in Nature with many biological activities, including the antineoplastic cytotoxicity, that have inspired this work. Here, we present a cytotoxic structure-activity relationship of several diterpenylhydroquinone (DTHQ) derivatives, obtained from the natural labdane diterpenoid myrceocommunic acid used as starting material. Different structural modifications, that changed the functionality and stereochemistry of the decalin, have been implemented on the bicyclic core through epoxidation, ozonolysis or decarboxylation, and through induction of biomimetic breaks and rearrangements of the diterpene skeleton. All the isomers generated were completely characterized by spectroscopic procedures. The resulting compounds have been tested in vitro on cultured cancer cells, showing their relevant antineoplastic cytotoxicity, with GI50 values in the µM and sub-µM range. The rearranged compound 8 showed the best cytotoxic results, with GI50 at the submicromolar range, retaining the cytotoxicity level of the parent compounds. In this report, the versatility of the labdane skeleton for chemical transformation and the interest to continue using structural modifications to obtain new bioactive compounds are demonstrated.

(Po)STAC (Polycistronic SunTAg modified CRISPR) enables live-cell and fixed-cell super-resolution imaging of multiple genes.

CRISPR/dCas9-based labeling has allowed direct visualization of genomic regions in living cells. However, poor labeling efficiency and signal-to-background ratio have limited its application to visualize genome organization using super-resolution microscopy. We developed (Po)STAC (Polycistronic SunTAg modified CRISPR) by combining CRISPR/dCas9 with SunTag labeling and polycistronic vectors. (Po)STAC enhances both labeling efficiency and fluorescence signal detected from labeled loci enabling live cell imaging as well as super-resolution fixed-cell imaging of multiple genes with high spatiotemporal resolution.

A Novel Cytotoxic Conjugate Derived from the Natural Product Podophyllotoxin as a Direct-Target Protein Dual Inhibitor.

Natural products are the ideal basis for the design of novel efficient molecular entities. Podophyllotoxin, a naturally occurring cyclolignan, is an example of natural product which displays a high versatility from a biological activity point of view. Based on its unique chemical structure, different derivatives have been synthesized presenting the original antitumoral properties associated with the compound, i.e., the tubulin polymerization inhibition and arising anti-topoisomerase II activity from structural modifications on the cyclolignan skeleton. In this report, we present a novel conjugate or hybrid which chemically combines both biological activities in one single molecule. Chemical design has been planned based in our lead compound, podophyllic aldehyde, as an inhibitor of tubulin polymerization, and in etoposide, an approved antitumoral drug targeting topoisomerase II. The cytotoxicity and selectivity of the novel synthetized hybrid has been evaluated in several cell lines of different solid tumors. In addition, these dual functional effects of the novel compound have been also evaluated by molecular docking approaches.

Cytinus hypocistis (L.) L. subsp. macranthus Wettst.: Nutritional Characterization.

The habit of eating wild plants in Europe is often associated with times of famine; an example of such is the nectar of Cytinus hypocistis (L.) L., a parasitic plant. To the authors' best knowledge, there are no studies on its nutritional and chemical composition; thus, the whole C. hypocistis (L.) L. subsp. macranthus Wettst. plant (CH) and its nectar (NCH) were nutritionally and chemically characterized. The proximate composition of CH and NCH were very similar in terms of energy, ash, and carbohydrate content. Protein and fat were approximately 2-fold higher in NCH, and crude fiber was 4.6-fold higher in CH compared to NCH. Fructose, glucose, sucrose, and trehalose were the free sugars present in both samples. Oxalic, malic, and citric acids were the identified organic acids in both samples, with citric acid as the most abundant molecule. For both samples, polyunsaturated and saturated fatty acids (PUFA and SFA, respectively) predominate over monounsaturated fatty acids (MUFA) due to the significant contribution of linoleic and palmitic acids, respectively. However, unsaturated fatty acids (UFA) prevail over SFA in CH and NCH. Therefore, CH proved to be an excellent source of nutritional compounds, which supports its use during past periods of scarcity.

Anti-Herpetic, Anti-Dengue and Antineoplastic Activities of Simple and Heterocycle-Fused Derivatives of Terpenyl-1,4-Naphthoquinone and 1,4-Anthraquinone.

Quinones are secondary metabolites of higher plants associated with many biological activities, including antiviral effects and cytotoxicity. In this study, the anti-herpetic and anti-dengue evaluation of 27 terpenyl-1,4-naphthoquinone (NQ), 1,4-anthraquinone (AQ) and heterocycle-fused quinone (HetQ) derivatives was done in vitro against Human Herpesvirus (HHV) type 1 and 2, and Dengue virus serotype 2 (DENV-2). The cytotoxicity on HeLa and Jurkat tumor cell lines was also tested. Using plaque forming unit assays, cell viability assays and molecular docking, we found that NQ 4 was the best antiviral compound, while AQ 11 was the most active and selective molecule on the tested tumor cells. NQ 4 showed a fair antiviral activity against Herpesviruses (EC50: <0.4 µg/mL, <1.28 µM) and DENV-2 (1.6 µg/mL, 5.1 µM) on pre-infective stages. Additionally, NQ 4 disrupted the viral attachment of HHV-1 to Vero cells (EC50: 0.12 µg/mL, 0.38 µM) with a very high selectivity index (SI = 1728). The in silico analysis predicted that this quinone could bind to the prefusion form of the E glycoprotein of DENV-2. These findings demonstrate that NQ 4 is a potent and highly selective antiviral compound, while suggesting its ability to prevent Herpes and Dengue infections. Additionally, AQ 11 can be considered of interest as a leader for the design of new anticancer agents.

Marine Alkylpurines: A Promising Group of Bioactive Marine Natural Products.

Marine secondary metabolites with a purine motif in their structure are presented in this review. The alkylpurines are grouped according to the size of the alkyl substituents and their location on the purine ring. Aspects related to the marine source, chemical structure and biological properties are considered together with synthetic approaches towards the natural products and bioactive analogues. This review contributes to studies of structure-activity relationships for these metabolites and highlights the potential of the sea as a source of new lead compounds in diverse therapeutic fields.

Bioactive Prenyl- and Terpenyl-Quinones/Hydroquinones of Marine Origin †.

The sea is a rich source of biological active compounds, among which terpenyl-quinones/hydroquinones constitute a family of secondary metabolites with diverse pharmacological properties. The chemical diversity and bioactivity of those isolated from marine organisms in the last 10 years are summarized in this review. Aspects related to synthetic approaches towards the preparation of improved bioactive analogues from inactive terpenoids are also outlined.

Optical transmission properties of Pentelic and Paros marble.

Ancient Greek and Roman sources report that the statue of Zeus in Olympia had a head, and in particular eyes, similar to the description of Zeus by Homer, so we think that the statue was visible to the human eye. Since the temple was 12 m high, and had a small door and no windows, the illumination of the statue by conventional media is questionable. The aim of this paper is to characterize the optical transmission of Paros and Pentelic marble to demonstrate that it was possible to have the Zeus temple illuminated through the roof marble tiles. Spectral absolute transmittance measurements were taken in samples with different thicknesses using a calibrated spectrophotometer, as well as total transmittance measurements using a luxmeter. The results show that both types of marble transmit light and that Pentelic marble has a higher transmittance in the visible range than Paros marble in some cases and hence could have been one reason, among others, to change the type of marble in the roof in antiquity.

Generating Human Pancreatic Tissue Slices to Study Endocrine and Exocrine Pancreas Physiology.

It is crucial to study the human pancreas to understand the pathophysiological mechanisms associated with type 1 (T1D) and 2 diabetes (T2D) as well as the pancreas endocrine and exocrine physiology and interplay. Much has been learned from the study of isolated pancreatic islets, but this prevents examining their function and interactions in the context of the whole tissue. Pancreas slices provide a unique opportunity to explore the physiology of normal, inflamed, and structurally damaged islets within their native environment, in turn allowing the study of interactions between endocrine and exocrine compartments to better investigate the complex dynamics of pancreatic tissue. Thus, the adoption of the living pancreas slice platform represents a significant advancement in the field. This protocol describes how to generate living tissue slices from deceased organ donors by tissue embedding in agarose and vibratome slicing as well as their utilization to assess functional readouts such as dynamic secretion and live cell imaging.

Unveiling the metabolites underlying the skin anti-ageing properties of Cytinus hypocistis (L.) L. through a biochemometric approach.

BACKGROUND: The genus Cytinus, recognised as one of the most enigmatic in the plant kingdom, has garnered attention for its bioactive potential, particularly its skin anti-ageing properties. Despite this recognition, much remains to be accomplished regarding deciphering and isolating its most active compounds. HYPOTHESIS: This study aimed to identify the compounds responsible for C. hypocistis skin anti-ageing potential. METHODS: Using multivariate analysis, a biochemometric approach was applied to identify the discriminant metabolites by integrating extracts' chemical profile (Liquid Chromatography-High-Resolution Mass Spectrometry, LCHRMS) and bioactive properties. The identified bioactive metabolite was structurally elucidated by 1D and 2D Nuclear Magnetic Resonance (NMR). RESULTS: Among the studied bioactivities, the anti-elastase results exhibited a significant variation among the samples from different years. After the biochemometric analysis, the compound 2,3:4,6-bis(hexahydroxydiphenoyl)glucose, with a molecular mass of 784.075 Da, was structurally elucidated as the discriminant feature responsible for the outstanding human neutrophil elastase inhibition. Remarkably, the subfraction containing this compound exhibited a tenfold improvement in neutrophil elastase inhibition efficacy compared to the crude extract; its effectiveness fell within the same range as SPCK, a potent irreversible neutrophil elastase inhibitor. Moreover, this subfraction displayed no cytotoxicity or phototoxicity and excellent efficacy for the tested anti-ageing properties. CONCLUSIONS: Hydrolysable tannins were confirmed as the metabolites behind C. hypocistis skin anti-ageing properties, effectively mitigating critical molecular mechanisms that influence the phenotypically distinct ageing clinical manifestations. Pedunculagin was particularly effective in inhibiting neutrophil elastase, considered one of the most destructive enzymes in skin ageing.

Toward Ameliorating Insulin Resistance: Targeting a Novel PAK1 Signaling Pathway Required for Skeletal Muscle Mitochondrial Function.

The p21-activated kinase 1 (PAK1) is required for insulin-stimulated glucose uptake in skeletal muscle cells. However, whether PAK1 regulates skeletal muscle mitochondrial function, which is a central determinant of insulin sensitivity, is unknown. Here, the effect of modulating PAK1 levels (knockdown via siRNA, overexpression via adenoviral transduction, and/or inhibition of activation via IPA3) on mitochondrial function was assessed in normal and/or insulin-resistant rat L6.GLUT4myc and human muscle (LHCN-M2) myotubes. Human type 2 diabetes (T2D) and non-diabetic (ND) skeletal muscle samples were also used for validation of the identified signaling elements. PAK1 depletion in myotubes decreased mitochondrial copy number, respiration, altered mitochondrial structure, downregulated PGC1α (a core regulator of mitochondrial biogenesis and oxidative metabolism) and PGC1α activators, p38 mitogen-activated protein kinase (p38MAPK) and activating transcription factor 2 (ATF2). PAK1 enrichment in insulin-resistant myotubes improved mitochondrial function and rescued PGC1α expression levels. Activated PAK1 was localized to the cytoplasm, and PAK1 enrichment concurrent with p38MAPK inhibition did not increase PGC1α levels. PAK1 inhibition and enrichment also modified nuclear phosphorylated-ATF2 levels. T2D human samples showed a deficit for PGC1α, and PAK1 depletion in LHCN-M2 cells led to reduced mitochondrial respiration. Overall, the results suggest that PAK1 regulates muscle mitochondrial function upstream of the p38MAPK/ATF2/PGC1α-axis pathway.