Exploring Marine Alkaloids: A Natural Approach to Cancer Treatment.

Cancer is one of the most complicated and prevalent diseases in the world, and its incidence is growing worldwide. Natural products containing pharmacological activity are widely used in the pharmaceutical industry, especially in anticancer drugs, due to their diverse structures and distinctive functional groups that inspire new drug results by means of synthetic chemistry. Terrestrial medicinal plants have traditionally been the primary source for developing natural products (NPs). However, over the past thirty years, marine organisms such as invertebrates, plants, algae, and bacteria have revealed many new pharmaceutical compounds known as marine NPs. This field constantly evolves as a discipline in molecular targeted drug discovery, incorporating advanced screening tools that have revolutionised and become integral to modern antitumor research. This review discusses recent studies on new natural anticancer alkaloids obtained from marine organisms. The paper illustrates the structure and origin of marine alkaloids and demonstrates the cytotoxic action of new alkaloids from several structural families and their synthetic analogs. The most recent findings about the potential or development of some of them as novel medications, together with the status of our understanding of their current mechanisms of action, are also compiled.

Growth factor-dependent phosphorylation of Gαi shapes canonical signaling by G protein-coupled receptors.

A long-standing question in the field of signal transduction is how distinct signaling pathways interact with each other to control cell behavior. Growth factor receptors and G protein-coupled receptors (GPCRs) are the two major signaling hubs in eukaryotes. Given that the mechanisms by which they signal independently have been extensively characterized, we investigated how they may cross-talk with each other. Using linear ion trap mass spectrometry and cell-based biophysical, biochemical, and phenotypic assays, we found at least three distinct ways in which epidermal growth factor affected canonical G protein signaling by the Gi-coupled GPCR CXCR4 through the phosphorylation of Gαi. Phosphomimicking mutations in two residues in the αE helix of Gαi (tyrosine-154/tyrosine-155) suppressed agonist-induced Gαi activation while promoting constitutive Gßγ signaling. Phosphomimicking mutations in the P loop (serine-44, serine-47, and threonine-48) suppressed Gi activation entirely, thus completely segregating growth factor and GPCR pathways. As expected, most of the phosphorylation events appeared to affect intrinsic properties of Gαi proteins, including conformational stability, nucleotide binding, and the ability to associate with and to release Gßγ. However, one phosphomimicking mutation, targeting the carboxyl-terminal residue tyrosine-320, promoted mislocalization of Gαi from the plasma membrane, a previously uncharacterized mechanism of suppressing GPCR signaling through G protein subcellular compartmentalization. Together, these findings elucidate not only how growth factor and chemokine signals cross-talk through the phosphorylation-dependent modulation of Gαi but also how such cross-talk may generate signal diversity.

Insights into the Therapeutic Uses of Plant Derive Phytocompounds on Diabetic Nephropathy.

Diabetic nephropathy (DN) is one of the primary consequences of diabetes mellitus, affecting many people worldwide and is the main cause of death under the age of sixty. Reactive oxygen species (ROS) production rises during hyperglycemia and is crucial to the development of diabetic complications. Advanced glycation end products (AGEs) are produced excessively in a diabetic state and are accumulated in the kidney, where they change renal architecture and impair renal function. Another important targeted pathway for the formation of DN includes nuclear factor kappa-B (NF-kB), Nuclear factor E2-related factor 2 (Nrf2), NLR family pyrin domain containing 3 (NLRP3), protein kinase B/mammalian target of rapamycin (Akt/mTOR), and autophagy. About 40% of individuals with diabetes eventually acquire diabetic kidney disease and end-stage renal disease that needs hemodialysis, peritoneal dialysis, or kidney transplantation to survive. The current state of acceptable therapy for this kidney ailment is limited. The studies revealed that some naturally occurring bioactive substances might shield the kidney by controlling oxidative stress, renal fibrosis, inflammation, and autophagy. In order to provide new potential therapeutic lead bioactive compounds for contemporary drug discovery and clinical management of DN, this review was designed to examine the various mechanistic pathways by which conventional plants derive phytocompounds that are effective for the control and treatment of DN.

Aquaporins: a vital nexus in H2O2-gasotransmitter signaling.

Land plants have evolved with a complex mechanism of water uptake facilitated by the activity of aquaporins under normal and challenging environments. However, we lack a clear understanding of its interactions with reactive oxygen species, particularly hydrogen peroxide (H2O2) and the gasotransmitters nitric oxide (NO) and hydrogen sulfide (H2S), under oxidative stress. Here, we assess the crosstalk of aquaporin function, H2O2 homeostasis, and NO-H2S signaling in plants and provide a computational prediction of cysteine-based oxidative post-translational modifications (oxiPTMs) in plant aquaporins. We propose that aquaporin activity could be regulated by three major oxiPTMs, S-nitrosation, S-sulfenylation, and persulfidation, mediated by NO, H2O2, and H2S, respectively. Therefore, aquaporins might be key players in the gasotransmitter-mediated long-distance oxidative stress signals in plant cells.

Nanovehicles for melatonin: a new journey for agriculture.

The important role of melatonin in plant growth and metabolism together with recent advances in the potential use of nanomaterials have opened up interesting applications in agriculture. Various nanovehicles have been explored as melatonin carriers in animals, and it is now important to explore their application in plants. Recent findings have substantiated the use of silicon and chitosan nanoparticles (NPs) in targeting melatonin to plant tissues. Although melatonin is an amphipathic molecule, nanocarriers can accelerate its uptake and transport to various plant organs, thereby relieving stress and improving plant shelf-life in the post-harvest stages. We review the scope and biosafety concerns of various nanomaterials to devise novel methods for melatonin application in crops and post-harvest products.

Early diagnostic biomarkers for acute kidney injury using cisplatin-induced nephrotoxicity in rat model.

Chronic kidney diseases (CKD) caused by acute kidney injury (AKI) results rapid and reversible loss in renal function. A real-time, highly accurate, and sensitive acute kidney injury biomarker is urgently required in order to keep these patients alive and prevent end stage renal disease and related complications that include hypertension, fluid and electrolyte retention, metabolic acidosis, anemia, stroke etc. This study was designed to develop a specific and sensitive model for the early identification of renal damage in male albino rats. Using a single intraperitoneal dose of cisplatin (10 mg/kg body weight) to the rats, the various duration-dependent nephrotoxic activities were compared using multiple physiological, biochemical, genomic, and histopathological markers. We looked into when renal dysfunction would start occurring after receiving a single high dose of cisplatin while blood urea nitrogen (BUN) and serum creatinine (sCr) remained normal. Following a single cisplatin injection, various measurements were taken in plasma, urine, and/or kidney tissues of rats euthanized on days 1, 2, 3, 5, and 7. When the urine kidney injury molecule (KIM-1), interleukine 18 (IL-18), nephrin, neutrophil gelatinase-associated lipocalin (NGAL) and serum cystatin C (Cys C) levels are greatly raised on day 3 after cisplatin treatment, BUN and sCr levels remain normal. Nephrotoxicity of cisplatin is also indicated by the upregulated mRNA expression of KIM-1, IL-18, Cys C, and NGAL and downregulated expression of nephrin in kidney tissue at very initial stage. Protein expression of KIM-1, IL-18 and NGAL level of kidney tissues was upregulated indicated confirmatory results done by western blot. Utilising an array of kidney impairment indicators has emerged as an earlier, more effective, and more reliable technique to diagnose AKI when compared to the most sophisticated signs now available.

Diverse gut pathogens exploit the host engulfment pathway via a conserved mechanism.

Macrophages clear infections by engulfing and digesting pathogens within phagolysosomes. Pathogens escape this fate by engaging in a molecular arms race; they use WxxxE motif-containing "effector" proteins to subvert the host cells they invade and seek refuge within protective vacuoles. Here, we define the host component of the molecular arms race as an evolutionarily conserved polar "hot spot" on the PH domain of ELMO1 (Engulfment and Cell Motility protein 1), which is targeted by diverse WxxxE effectors. Using homology modeling and site-directed mutagenesis, we show that a lysine triad within the "patch" directly binds all WxxxE effectors tested: SifA (Salmonella), IpgB1 and IpgB2 (Shigella), and Map (enteropathogenic Escherichia coli). Using an integrated SifA-host protein-protein interaction network, in silico network perturbation, and functional studies, we show that the major consequences of preventing SifA-ELMO1 interaction are reduced Rac1 activity and microbial invasion. That multiple effectors of diverse structure, function, and sequence bind the same hot spot on ELMO1 suggests that the WxxxE effector(s)-ELMO1 interface is a convergence point of intrusion detection and/or host vulnerability. We conclude that the interface may represent the fault line in coevolved molecular adaptations between pathogens and the host, and its disruption may serve as a therapeutic strategy.

Bicyclic Peptide Library Screening for the Identification of Gαi Protein Modulators.

Noncanonical G protein activation and inactivation, particularly for the Gαi/s protein subfamilies, have long been a focus of chemical research. Combinatorial libraries were already effectively applied to identify modulators of the guanine-nucleotide exchange, as can be exemplified with peptides such as KB-752 and GPM-1c/d, the so-called guanine-nucleotide exchange modulators. In this study, we identified novel bicyclic peptides from a combinatorial library screening that show prominent properties as molecular switch-on/off modulators of Gαi signaling. Among the series of hits, the exceptional paradigm of GPM-3, a protein and state-specific bicyclic peptide, is the first chemically identified GAP (GTPase-activating protein) modulator with a high binding affinity for Gαi protein. Computational analyses identified and assessed the structure of the bicyclic peptides, novel ligand-protein interaction sites, and their subsequent impact on the nucleotide binding site. This approach can therefore lead the way for the development of efficient chemical biological probes targeting Gαi protein modulation within a cellular context.

Diverse Gut Pathogens Exploit the Host Engulfment Pathway via a Conserved Mechanism.

Macrophages clear infections by engulfing and digesting pathogens within phagolysosomes. Pathogens escape this fate by engaging in a molecular arms race; they use WxxxE motif-containing effector proteins to subvert the host cells they invade and seek refuge within protective vacuoles. Here we define the host component of the molecular arms race as an evolutionarily conserved polar hotspot on the PH-domain of ELMO1 (Engulfment and Cell Motility1), which is targeted by diverse WxxxE-effectors. Using homology modeling and site-directed mutagenesis, we show that a lysine triad within the patch directly binds all WxxxE-effectors tested: SifA (Salmonella), IpgB1 and IpgB2 (Shigella), and Map (enteropathogenic E. coli). Using an integrated SifA-host protein-protein interaction (PPI) network, in-silico network perturbation, and functional studies we show that the major consequences of preventing SifA-ELMO1 interaction are reduced Rac1 activity and microbial invasion. That multiple effectors of diverse structure, function, and sequence bind the same hotpot on ELMO1 suggests that the WxxxE-effector(s)-ELMO1 interface is a convergence point of intrusion detection and/or host vulnerability. We conclude that the interface may represent the fault line in co-evolved molecular adaptations between pathogens and the host and its disruption may serve as a therapeutic strategy.

A Multiomic Analysis Reveals How Breast Cancers Disseminated to the Bone Marrow Acquire Aggressive Phenotypes through Tumor-Stroma Tunnels.

Estrogen receptor-positive (ER+) breast cancer commonly disseminates to bone marrow, where interactions with mesenchymal stromal cells (MSCs) shape disease trajectory. We modeled these interactions with tumor-MSC co-cultures and used an integrated transcriptome-proteome-network- analyses workflow to identify a comprehensive catalog of contact-induced changes. Induced genes and proteins in cancer cells, some borrowed and others tumor-intrinsic, were not recapitulated merely by conditioned media from MSCs. Protein-protein interaction networks revealed the rich connectome between 'borrowed' and 'intrinsic' components. Bioinformatic approaches prioritized one of the 'borrowed' components, CCDC88A /GIV, a multi-modular metastasis-related protein which has recently been implicated in driving one of the hallmarks of cancers, i.e., growth signaling autonomy. MSCs transferred GIV protein to ER+ breast cancer cells (that lack GIV) through tunnelling nanotubes via connexin (Cx)43-facilitated intercellular transport. Reinstating GIV alone in GIV-negative breast cancer cells reproduced ∼20% of both the 'borrowed' and the 'intrinsic' gene induction patterns from contact co-cultures; conferred resistance to anti-estrogen drugs; and enhanced tumor dissemination. Findings provide a multiomic insight into MSC→tumor cell intercellular transport and validate how transport of one such candidate, GIV, from the haves (MSCs) to have-nots (ER+ breast cancer) orchestrates aggressive disease states.

Regulation of DNA damage response by trimeric G-proteins.

Upon sensing DNA double-strand breaks (DSBs), eukaryotic cells either die or repair DSBs via one of the two competing pathways, i.e., non-homologous end-joining (NHEJ) or homologous recombination (HR). We show that cell fate after DSBs hinges on GIV/Girdin, a guanine nucleotide-exchange modulator of heterotrimeric Giα•ßγ protein. GIV suppresses HR by binding and sequestering BRCA1, a key coordinator of multiple steps within the HR pathway, away from DSBs; it does so using a C-terminal motif that binds BRCA1's BRCT-modules via both phospho-dependent and -independent mechanisms. Using another non-overlapping C-terminal motif GIV binds and activates Gi and enhances the "free" Gßγ→PI-3-kinase→Akt pathway, which promotes survival and is known to suppress HR, favor NHEJ. Absence of GIV, or loss of either of its C-terminal motifs enhanced cell death upon genotoxic stress. Because GIV selectively binds other BRCT-containing proteins suggests that G-proteins may fine-tune sensing, repair, and survival after diverse types of DNA damage.

COVID-19 lockdown and distressed reverse migration enhance human-tiger conflict in Sundarban: An eco-psychiatric observation.

COVID-19 lockdown enforced distressed reverse migration in Sundarban, which caused an unprecedented population addition to the already devastated fragile Sundarban ecosystem. Acute poverty and food crisis prompted many migrants to explore forest-based living, thus enhancing fatal human-tiger conflicts. Families of deceased migrants face significant mental health trauma and catastrophic psychosocial consequences.

OsCyp2-P, an auxin-responsive cyclophilin, regulates Ca2+ calmodulin interaction for an ion-mediated stress response in rice.

OsCYP2-P is an active cyclophilin (having peptidyl-prolyl cis/trans-isomerase activity, PPIase) isolated from the wild rice Pokkali having a natural capacity to grow and yield seeds in coastal saline regions of India. Transcript abundance analysis in rice seedlings showed the gene is inducible by multiple stresses, including salinity, drought, high temperature, and heavy metals. To dissect the role of OsCYP2-P gene in stress response, we raised overexpression (OE) and knockdown (KD) transgenic rice plants with >2-3 folds higher and approximately 2-fold lower PPIase activity, respectively. Plants overexpressing this gene had more favorable physiological and biochemical parameters (K+ /Na+ ratio, electrolytic leakage, membrane damage, antioxidant enzymes) than wild type, and the reverse was observed in plants that were knocked down for this gene. We propose that OsCYP2-P contributes to stress tolerance via maintenance of ion homeostasis and thus prevents toxic cellular ion buildup and membrane damage. OE plants were found to have a higher harvest index and higher number of filled grains under salinity and drought stress than wild type. OsCYP2-P interacts with calmodulin, indicating it functions via the Ca-CaM pathway. Compared to the WT, the germinating OE seeds exhibited a substantially higher auxin level, and this hormone was below the detection limits in the WT and KD lines. These observations strongly indicate that OsCyp2-P affects the signaling and transport of auxin in rice.

Proficient Novel Biomarkers Guide Early Detection of Acute Kidney Injury: A Review.

The definition of acute kidney injury (AKI), despite improvements in criteria, continues to be based on the level of serum creatinine and urinary output that do not specifically indicate tubular function or injury, or glomerular function or injury that is not significant enough to warrant acute hospitalization of the patient. Finding novel biomarkers of AKI has become a major focus nowadays in nephrology to overcome the further complications of end stage renal disease (ESRD). Many compounds, such as KIM 1, IL 18, NGAL, uromodulin, calprotectin, vanin 1, galactin 3, platelet-derived growth factor (PDGF), urinary Na+/H+ exchanger isoform 3 (NHE3), retinol binding protein (RBP) and Cystatin C, are released from the renal tubules and thus any alterations in tubular function can be detected by measuring these parameters in urine. Additionally, glomerular injury can be detected by measuring immunoglobulin G, nephrin, podocalyxin, podocin, transferrin, netrin-1, pyruvate kinase M2, etc. in urine. These novel biomarkers will be useful for timing the initial insult and assessing the duration of AKI. According to available research, these biomarkers could be applied to assess the onset of AKI, distinguishing between kidney injury and dysfunction, directing the management of AKI, and enhancing disease diagnosis. Therefore, we intend to present recent developments in our understanding of significant biomarkers implicated in various aspects of renal damage. Numerous biomarkers are implicated in various pathophysiological processes that follow renal injury, and can improve prognosis and risk classification.

A long isoform of GIV/Girdin contains a PDZ-binding module that regulates localization and G-protein binding.

PDZ domains are one of the most abundant protein domains in eukaryotes and are frequently found on junction-localized scaffold proteins. Various signaling molecules bind to PDZ proteins via PDZ-binding motifs (PBM) and fine-tune cellular signaling. However, how such interaction affects protein function is difficult to predict and must be solved empirically. Here we describe a long isoform of the guanine nucleotide exchange factor GIV/Girdin (CCDC88A) that we named GIV-L, which is conserved throughout evolution, from invertebrates to vertebrates, and contains a PBM. Unlike GIV, which lacks PBM and is cytosolic, GIV-L localizes onto cell junctions and has a PDZ interactome (as shown through annotating Human Cell Map and BioID-proximity labeling studies), which impacts GIV-L's ability to bind and activate trimeric G-protein, Gαi, through its guanine-nucleotide exchange modulator (GEM) module. This GEM module is found exclusively in vertebrates. We propose that the two functional modules in GIV may have evolved sequentially: the ability to bind PDZ proteins via the PBM evolved earlier in invertebrates, whereas G-protein binding and activation may have evolved later only among vertebrates. Phenotypic studies in Caco-2 cells revealed that GIV and GIV-L may have antagonistic effects on cell growth, proliferation (cell cycle), and survival. Immunohistochemical analysis in human colon tissues showed that GIV expression increases with a concomitant decrease in GIV-L during cancer initiation. Taken together, these findings reveal how regulation in GIV/CCDC88A transcript helps to achieve protein modularity, which allows the protein to play opposing roles either as a tumor suppressor (GIV-L) or as an oncogene (GIV).

Receptor tyrosine kinases activate heterotrimeric G proteins via phosphorylation within the interdomain cleft of Gαi.

The molecular mechanisms by which receptor tyrosine kinases (RTKs) and heterotrimeric G proteins, two major signaling hubs in eukaryotes, independently relay signals across the plasma membrane have been extensively characterized. How these hubs cross-talk has been a long-standing question, but answers remain elusive. Using linear ion-trap mass spectrometry in combination with biochemical, cellular, and computational approaches, we unravel a mechanism of activation of heterotrimeric G proteins by RTKs and chart the key steps that mediate such activation. Upon growth factor stimulation, the guanine-nucleotide exchange modulator dissociates Gαi•ßγ trimers, scaffolds monomeric Gαi with RTKs, and facilitates the phosphorylation on two tyrosines located within the interdomain cleft of Gαi. Phosphorylation triggers the activation of Gαi and inhibits second messengers (cAMP). Tumor-associated mutants reveal how constitutive activation of this pathway impacts cell's decision to "go" vs. "grow." These insights define a tyrosine-based G protein signaling paradigm and reveal its importance in eukaryotes.

GIV•Kindlin Interaction Is Required for Kindlin-Mediated Integrin Recognition and Activation.

Cells perceive and respond to the extracellular matrix via integrin receptors; their dysregulation has been implicated in inflammation and cancer metastasis. Here we show that a guanine nucleotide-exchange modulator of trimeric-GTPase Gαi, GIV (a.k.a Girdin), directly binds the integrin adaptor Kindlin-2. A non-canonical short linear motif within the C terminus of GIV binds Kindlin-2-FERM3 domain at a site that is distinct from the binding site for the canonical NPxY motif on the -integrin tail. Binding of GIV to Kindlin-2 allosterically enhances Kindlin-2's affinity for ß1-integrin. Consequently, integrin activation and clustering are maximized, which augments cell adhesion, spreading, and invasion. Findings elucidate how the GIV•Kindlin-2 complex has a 2-fold impact: it allosterically synergizes integrin activation and enables ß1-integrins to indirectly access and modulate trimeric GTPases via the complex. Furthermore, Cox proportional-hazard models on tumor transcriptomics provide trans-scale evidence of synergistic interactions between GIV•Kindlin-2•ß1-integrin on time to progression to metastasis.

Discovery of New Inhibitors of Hepatitis C Virus NS3/4A Protease and Its D168A Mutant.

Hepatitis C virus (HCV) is a human pathogen with high morbidity. The HCV NS3/4A protease is essential for viral replication and is one of the top three drug targets. Several drugs targeting the protease have been developed, but drug-resistant mutant strains emerged. Here, we screened a library and synthesized a novel class of small molecules based on a tryptophan derivative scaffold identified as HCV NS3/4A protease inhibitors that are active against both wild type and mutant form of the protease. Only the compounds with predicted binding poses not affected by the most frequent mutations in the active site were selected for experimental validation. The antiviral activities were evaluated by replicon and enzymatic assays. Twenty-two compounds were found to inhibit HCV with EC50 values ranging between 0.64 and 63 µM with compound 22 being the most active. In protease assays, 22 had a comparable inhibition profile for the common mutant HCV GT1b D168A and the wild-type enzyme. However, in the same assay, the potency of the approved drug, simeprevir, decreased 5.7-fold for the mutant enzyme relative to the wild type. The top three inhibitors were also tested against four human serine proteases and were shown to be specific to the viral protease. The fluorescence-based cell viability assay demonstrated a sufficient therapeutic range for the top three candidates.

Hypoxia: A cause of acute renal failure and alteration of gastrointestinal microbial ecology.

Oxygen is very important to the existence of life. Oxygen deficiency, defined as hypoxia, elicits adaptive responses in cells and tissues. Lower oxygen concentration can cause the alteration of renal function, affects the maintenance of a balance of the body fluids, electrolytes, pH, and blood pressure homeostasis. Impaired fluid regulation could, in addition, contribute to the precipitation of pulmonary edema and exacerbate hypoxemia which may accelerate the progression of chronic kidney disease. In this context, the present study attempted to evaluate the association of renal injury and oxidative stress at different atmospheric pressures (1829, 3657, and 5486 m). Limited fecal analysis of experimental animals was also done to evaluate the impact of hypobaric hypoxia on the composition of dominant gastrointestinal microbiota. The study was performed on 24 male Wister strain rats and divided into four groups (C, HA-I, HA-II, and HA-III), and exposure was carried out for seven days period. In hypoxic exposure rats, plasma urea, creatinine, electrolytes and malonaldehyde level elevated and catalase and superoxide dismutase level diminished significantly compared to the controls. Increase in blood uremia profile, toxicity markers, and lipid peroxidation marker enzymes indicated that hypoxia causes renal failure. Histological structures of the kidney of group HA-II and HA-III animals showed severe disorganization of glomerulus and dilation of renal tubules. These results indicate nephrotoxicity or acute renal failure can occur at hypobaric hypoxia and it also affected the gut microbial population. This alteration was observed significantly above 3000 m.