Regulation Of Cell Growth Research Articles

BIOACTIVE COMPOUNDS OF Moringa oleifera AS KRASG12C INHIBITORS IN COLORECTAL CANCER: IN SILICO STUDY

KRAS is a GTPase enzyme that regulates cell growth and division. Mutations in KRAS can lead to its permanent activation, resulting in uncontrolled cell growth and cancer progression. Approximately 30–44% of colorectal cancer cases harbor KRAS mutations, with 1–3% involving the KRASG12C variant. Historically considered "undruggable," recent advancements, such as Sotorasib, have demonstrated the potential to target KRASG12C effectively, making it a promising focus for drug discovery. Moringa oleifera, a plant rich in phytochemicals, is a potential source of bioactive compounds with therapeutic applications. In this study, 218 compounds derived from M. oleifera were screened using molecular docking, targeting KRASG12C. Quercetin (3) exhibited the lowest binding affinity (-9.37 kcal/mol) and showed interactions with key residues, including GLN100A, VAL104A, LYS17A, and TYR97A, suggesting a binding mechanism similar to that of Sotorasib as native ligand. The physicochemical analysis further revealed high gastrointestinal absorption, good lipophilicity, and favorable bioavailability scores for Quercetin (3), supporting its potential as a drug candidate. These findings highlight the potential of M. oleifera compounds, particularly quercetin (3), as inhibitors of KRASG12C in colorectal cancer.

The involvement of T1R family receptors expressed outside the oral cavity in the regulation of metabolism

The membrane T1R taste receptor family interacts with sweet substances – carbohydrates, artificial sweeteners and some amino acids. An important result of research in the 21st century was the discovery of abundant expression of these receptors outside of the oral cavity, mainly in cells actively involved in metabolic processes: enteroendocrine cells of the intestine, pancreatic β-cells, adipose and bone tissue, etc. This review integrates and analyzes current data on the role of extraoral T1R receptors in the regulation of metabolism, cell growth and differentiation, which is achieved through modulation of hormone secretion (insulin, GLP-1, GIP), activity of membrane transporters and cell growth and proliferation factors. T1R mediated cellular responses to nutrients, mechanisms of signal transduction, effects on inositol triphosphate, cAMP and intracellular Ca2+ levels, stimulatory effects on glucose transporters SGLT1 and GLUT2, effects on mTOR and hormone secretion are described. The interaction of membrane receptor mechanisms and metabolic detection of glucose by the ATP/ADP ratio in the cell cytoplasm is also discussed. Putative evolutionary adaptation of metabolic processes related to nutrition and manifested in polymorphism of genes encoding T1R proteins is presented. It is suggested that extraoral taste receptors for sweet substances and amino acids may be a target for therapeutic interventions in obesity, hyperglycemia, insulin resistance, and hepatosteatosis.

A recurrent variant in PPP2R5C identified in individuals with macrocephaly, intellectual disability, and seizures.

PPP2R5C encodes a B-type regulatory subunit of protein phosphatase 2A (PP2A). This protein serine/threonine phosphatase is a component of multiple signaling pathways and is an established negative regulator of cell division, growth and proliferation. De novo variants in other subunits of protein phosphatase 2A are associated with neurodevelopment disorders and intellectual disability. We report two unrelated affected individuals with a recurrent variant in PPP2R5C (c.457G>A: p.(Glu153Lys)). Core features in affected individuals include macrocephaly, intellectual disability, hypotonia, and seizures. The Glu153 residue is part of a highly conserved acidic loop and directly interacts with the PP2A catalytic subunit. Our results support heterozygous PPP2R5C missense variants as a potential cause of macrocephaly and neurodevelopmental disorder.

From nature’s pharmacy: harnessing bioactive phytoconstituents as fibroblast growth factor receptor 3 inhibitors for anti-cancer therapeutics

Fibroblast growth factor receptor 3 (FGFR3) is a key protein involved in regulating cell growth and development. Aberrant activation of FGFR3 has been linked to several diseases, including cancer and skeletal disorders. Therefore, identifying potential inhibitors of FGFR3 is of great interest in developing targeted therapies. In this study, we employed a combined docking and molecular dynamics simulation (MDS) approach to investigate the inhibitory potential of plant-based compounds against FGFR3. Here, we utilized structure-based virtual screening to identify potential phytoconstituents from the IMPPAT library with the ability to inhibit FGFR3 activity. The initial screening process involved molecular docking to assess the binding potential of the compounds towards FGFR3. Afterward, we employed various filters to determine physicochemical properties, ADMET, and PASS evaluation to identify potential hits against FGFR3. This process discovered two phytoconstituents, Cycloartobiloxanthone and Desoxylimonin, as promising candidates against FGFR3. These compounds exhibited favorable binding affinity, efficiency, and specific interaction towards the FGFR3 binding pocket. They preferred binding to the active site of FGFR3 and possessed desirable drug-like properties. To gain a deeper understanding of their interaction mechanism, conformational dynamics, and stability, we conducted all-atom MDS lasting 200 nanoseconds (ns) on the FGFR3-Cycloartobiloxanthone and FGFR3-Desoxylimonin complexes. The MDS consistently demonstrated the formation of stable protein-ligand complexes between FGFR3 and Cycloartobiloxanthone/Desoxylimonin throughout the trajectory. Based on these results, it can be inferred that Cycloartobiloxanthone and Desoxylimonin can potentially serve as valuable scaffolds in developing drugs targeting FGFR3 for cancer therapeutic after required validation.

Regulatory mechanisms governing GLI proteins in hedgehog signaling.

The Hedgehog (Hh) signaling pathway is critical for regulating cell growth, survival, fate determination, and the overall patterning of both vertebrate and invertebrate body plans. Aberrations in Hh signaling are associated with congenital abnormalities and tumorigenesis. In vertebrates, Hh signaling depends uniquely on primary cilia, microtubule-based organelles that extend from the cell surface. Over the last 2 decades, studies have demonstrated that key molecules regulating Hh signaling dynamically accumulate in primary cilia via intraflagellar transport systems. Moreover, through the primary cilia, extracellular signals are converted to stabilize GLI2 and GLI3 that are transcription factors that play a central role in regulating Hh signaling at the post-translational modification level. Recent in vivo and anatomical studies have uncovered crucial molecules that facilitate the conversion of extracellular signals into the intracellular stabilization of GLI2/GLI3 via primary cilia, emphasizing their essential roles in tissue development and tumorigenesis. This review explores the regulatory mechanisms of GLI2/GLI3 with a focus on mammalian tissue development.

Small Molecule Inhibitor of Protein Kinase C DeltaI (PKCδI) Decreases Inflammatory Pathways and Gene Expression and Improves Metabolic Function in Diet-Induced Obese Mouse Model.

Obesity promotes metabolic diseases such as type 2 diabetes and cardiovascular disease. PKCδI is a serine/threonine kinase which regulates cell growth, differentiation, and survival. Caspase-3 cleavage of PKCδI releases the C-terminal catalytic fragment (PKCδI_C), which promotes inflammation and apoptosis. We previously demonstrated an increase in PKCδI_C in human obese adipose tissue (AT) and adipocytes. Subsequently, we designed a small molecule drug called NP627 and demonstrated that NP627 specifically inhibited the release of PKCδI_C in vitro. Here, we evaluate the in vivo safety and efficacy of NP627 in a diet-induced obese (DIO) mouse model. The results demonstrate that NP627 treatment in DIO mice increased glucose uptake and inhibited the cleavage of PKCδI_C in the AT as well as in the kidney, spleen, and liver. Next, RNAseq analysis was performed on the AT from the NP627-treated DIO mice. The results show increases in ADIPOQ and CIDEC, upregulation of AMPK, PI3K-AKT, and insulin signaling pathways, while inflammatory pathways were decreased post-NP627 administration. Further, levels of lncRNAs associated with metabolic pathways were affected by NP627 treatment. In conclusion, the study demonstrates that NP627, a small-molecule inhibitor of PKCδI activity, is not toxic and that it improves the metabolic function of DIO mice in vivo.

Full-length RNA-Seq of the RHOH gene in human B cells reveals new exons and splicing patterns

The RhoH protein is a member of the Ras superfamily of guanosine triphosphate-binding proteins. RhoH is an atypical Rho family member that is always GTP-bound and thus always activated. It is restrictively expressed in normal hematopoietic cells, where it is a negative regulator of cell growth and survival. We previously analyzed the RHOH gene structure and demonstrated that this gene is composed of 7 exons, one single encoding exon located at the 3ʹ extremity of the gene, preceded by 6 noncoding exons. To further understand the transcription events associated with this gene, we performed full-length RNA-Seq on 12 B-cell lines. We identified new exons, new splice events and new splice sites, leading to the discovery of 38 RHOH mRNA molecules, 27 of which have never been described before. Here, we also describe new fusion transcripts. Moreover, our method allowed quantitative measurements of the different mRNA species relative to each other in relation to B-cell differentiation.

PIK3CA-Related Overgrowth Spectrum: Exploring Brain Growth From Fetal to Infant

BackgroundMegalencephaly-capillary malformation-polymicrogyria syndrome (MCAP) is a rare neurological disorder characterized by abnormal brain size, vascular malformations, and body overgrowth. MCAP is caused by somatic mosaicism of PIK3CA, a crucial gene in regulation of cell growth and survival, and is one of the disorders in the PIK3CA-related overgrowth spectrum. MethodsWe present a unique clinical report of a male infant diagnosed with MCAP from prenatal stages to age 12 months. Prenatal imaging unveiled ventricular asymmetry, later confirmed postnatally as megalencephaly. Genetic analysis identified a PIK3CA mutation. The patient underwent early interventions, including ventriculoperitoneal shunt placement and posterior fossa decompression. ResultsDespite early interventions, the patient developed progressive macrocrania, hydrocephalus, and significant neurodevelopmental delay. Multidisciplinary management and continuous neuroimaging were crucial in addressing complications associated with the disorder. ConclusionsThis case underscores the critical need for multidisciplinary care and continual neuroimaging surveillance to effectively navigate the progressive complications associated with PIK3CA-related overgrowth spectrum. The diagnostic hurdles and management challenges intrinsic to the disorder's natural course are elucidated. Although current treatments manage symptoms, emerging therapies hold promise for improving patient outcomes.

The LINC01094/miR-545-3p/SLC7A11 Signaling Axis Promotes the Development of Gastric Cancer by Regulating Cell Growth and Ferroptosis.

This study aimed to investigate the role and mechanism of action of LINC01094 in the development of gastric cancer (GC). The expression levels of LINC01094 in GC patients and healthy individuals were analyzed online using the Cancer Genome Atlas database. Quantitative real-time polymerase chain reaction (qRT-PCR) and Western blot analyses were performed to determine the expression of LINC01094/miR-545-3p/SLC7A11 in GC tissues and cells. Functional experiments (MTT assay, colony formation assay, and flow cytometry) were conducted to assess the effect of LINC01094 and miR-545-3p on cell proliferation, viability, apoptosis, cell cycle, and reactive oxygen species. Correlations between LINC01094 and miR-545-3p, as well as SLC7A11, were analyzed and validated using the dual-luciferase reporter assay and RNA immunoprecipitation. The levels of Fe2+, malondialdehyde, and glutathione in the cells were measured biochemically, and the protein expression levels of Bcl-2, cleaved caspase3, Cyclin D1, and p21 were detected by Western blotting. LINC01094 was significantly upregulated in the GC tissues and cells with a targeting relationship with miR-545-3p; the expression levels of LINC01094 and miR-545-3p were negatively correlated. Knockdown of LINC01094 notably inhibited the proliferation and viability of GC cells and promoted cell ferroptosis, which, however, was abrogated by the silencing of miR-545-3p. These findings indicate that miR-545-3p could target and positively correlate with SLC7A11 expression. Additionally, LINC01094 could promote GC cell progression and affect cellular ferroptosis by regulating the miR-545-3p/SLC7A11 signaling axis.

DDDR-26. IDENTIFICATION OF MODULATORS OF IDH INHIBITOR SENSITIVITY INIDH-MUTATED DIFFUSE GLIOMAS

Abstract Driver mutations in IDH1 and IDH2 characterize a substantial proportion of lower-grade diffuse gliomas in adults. Mutated IDH molecules cause the accumulation of D-2-hydroxyglutarate (D-2-HG), which perturbs many cellular functions, including metabolism, epigenetic regulation, and the ability to differentiate. This is notably associated with DNA and histone hyper-methylation. Recently, the newly developed IDH inhibitor, vorasidenib, was shown to delay tumor progression and the need for additional treatment in the groundbreaking INDIGO clinical trial. Nevertheless, the responses to vorasidenib were variable between patients, and so far have been established only for less aggressive disease. In addition, it is unclear to what extent vorasidenib can cause tumor regression. This highlights the need to identify molecules and pathways that control IDH inhibitor sensitivity. Towards this goal, we generated a new mouse model that combines Idh1R132H and Trp53 loss-of-function, targeted to oligodendrocyte progenitors. All the mutant mice develop diffuse gliomas that recapitulate the cardinal features of the corresponding human disease. We established multiple cell lines from these tumors, which retained expression of mutant IDH. The cells robustly produced D-2-HG, which was concentration-dependently suppressed by vorasidenib. Accordingly, vorasidenib could lower DNA methylation, and induce the expression of mature glial cell markers. To identify determinants of vorasidenib sensitivity, we performed genome-wide loss-of-function CRISPR/Cas9 functional genomics screens. In those experiments, targeting genes associated with astrocyte differentiation or Notch signaling enhanced cell fitness in the presence of vorasidenib, consistent with the anticipated effects of the drug on inducing cell differentiation. Conversely, vorasidenib-treated cells were more sensitive to the loss of regulators of cell growth and metabolism, and of some epigenetic regulators. These studies point to strategies that may enhance the efficacy of IDH inhibitors for the treatment of IDH mutated gliomas.

Regulatory-Associated Protein of mTOR-Mediated Signaling: A Nexus Between Tumorigenesis and Disease

RAPTOR (regulatory-associated protein of mTOR) is a pivotal component of the mammalian target of rapamycin complex 1 (mTORC1), playing a central role in regulating cell growth, metabolism and stress responses. As a scaffold protein, RAPTOR recruits key substrates such as eukaryotic initiation factor 4E-binding protein-1 (4E-BP1) and ribosomal protein S6 kinase (S6K), facilitating their phosphorylation by mTORC1, which in turn drives protein synthesis, lipid metabolism and cellular proliferation. Its regulatory function becomes especially crucial under conditions of nutrient deprivation or stress, where it enhances the stability of the mTORC1 complex, allowing cells to adapt to fluctuating environmental cues. The hyperactivation of mTORC1, largely mediated by RAPTOR, is frequently observed in various cancers, contributing to uncontrolled cell proliferation and tumorigenesis. Moreover, RAPTOR’s modulation of immune responses and metabolic pathways extends its influence beyond oncogenesis, impacting inflammatory diseases and metabolic disorders. This review meticulously elucidates RAPTOR’s structure, post-translational modifications as well as its indispensable role within the mTORC1 complex, emphasizing its regulatory functions in cellular growth, metabolic adaptation, immune response and disease pathology including oncogenesis. Furthermore, it explores emergent therapeutic avenues targeting RAPTOR-mediated mTORC1 signaling, underscoring their potential to revolutionize cancer treatment and the management of related pathophysiological conditions.

Phenotypic plasticity in bacterial elongation among closely related species.

Cell elongation is a fundamental component of the bacterial cell cycle and has been studied over many decades, in part owing to its mechanisms being a target of numerous antibiotic classes. While several distinct modes of cell elongation have been described, these studies have largely relied on a handful of model bacterial species. Therefore, we have a limited view of the diversity of cell elongation approaches that are employed by bacteria, and how these vary in response to evolutionary and environmental influences. Here, by employing fluorescent D-amino acids (FDAAs) to track the spatiotemporal dynamics of elongation, we reveal previously unsuspected diversity of elongation modes among closely related species of the Caulobacteraceae , with species-specific combinations of dispersed, midcell and polar elongation that can be either unidirectional or bidirectional. Using genetic, cell biology, and phylogenetic approaches, we demonstrate that evolution of unidirectional-midcell elongation is accompanied by changes in the localization pattern of the peptidoglycan synthase PBP2 and infer that elongation complexes display a high degree of phenotypic plasticity, both among the Caulobacteraceae and more widely among the Alphaproteobacteria. Demonstration that even closely related bacterial species employ highly distinct mechanisms of cell elongation reshapes our understanding of the evolution and regulation of bacterial cell growth, with broad implications for bacterial morphology, adaptation, and antibiotic resistance.

HSP70 promotes amino acid-dependent mTORC1 signaling by mediating CHIP-induced NPRL2 ubiquitination and degradation.

Mechanistic target of rapamycin complex 1 (mTORC1) is a master regulator of cell growth and its dysregulation leads to a variety of human diseases. Although NPRL2, an essential component of the GATOR1 complex, is reported to effectively suppress amino acid-induced mTORC1 activation, the regulation of NPRL2 protein stability is unclear. In this study, we show that chaperon-associated ubiquitin ligase CHIP interacts with NPRL2 and promotes its polyubiquitination and proteasomal degradation. Moreover, HSP70 mediates CHIP-induced ubiquitination and degradation of NPRL2. Consistently, overexpression of HSP70 enhances whereas HSP70 depletion inhibits amino acid-induced mTORC1 activation. Accordingly, knockdown of HSP70 promotes basal autophagic flux, and inhibits cell growth and proliferation. Taken together, these results demonstrated that HSP70 is a novel activator of mTORC1 through mediating CHIP-induced ubiquitination and degradation of NPRL2.

TOWARDS THE DESIGN OF LIGANDS OF THE INTERNAL POCKET TEADS C-TERMINAL DOMAIN

The Hippo pathway controls in organ size and tissue homeostasis through regulating cell growth, proliferation and apoptosis. Phosphorylation of the transcription co-activator YAP (Yes associated protein) and TAZ (Transcriptional coactivator with PDZ-binding motif) regulates their nuclear import and therefore their interaction with TEAD (Transcriptional Enhanced Associated Domain). YAP, TAZ and TEADs are dysregulated in several solid cancers making YAP/TAZ-TEAD interaction a new anti-cancer target. We identified by screening a small in-house library, 5-benzyloxindole which binds to hTEAD2 at its internal/palmitate pocket. Its optimization led to covalent inhibitors bearing different warhead. Soaking with hTEAD2 gave seven new crystal structures where the ligands occupied palmitate pocket. 5-Benzyloxyindoles armed with vinylsulfamide moiety inhibit YAP/TAZ-TEAD target genes expression and breast cancer cell proliferation at micromolar concentration.

IL-4 Downregulates PD-L1 Level Via SOCS1 Upregulation-Induced JNK Deactivation to Enhance Antitumor Immunity in In Vitro Colorectal Cancer.

Interleukin-4 (IL-4) controls cell growth and immune system regulation in tumorigenesis and can inhibit the growth of colon cancer cell lines, but the possible mechanism is unclear. In this study, we investigated the possible mechanism of IL-4 in colorectal cancer (CRC) through in vitro experiments. CRC cells received treatment with IL-4 (50 ng/mL), investigating the suppressor of cytokine signaling 1 (SOCS1)-related mechanism underlying the role of IL-4 in the progression and immunosuppression of CRC. The malignant processes of CRC cells and CD8+T cell-mediated immune response in CRC cells were determined by CCK-8, Transwell, wound healing, and flow cytometry assays. Programmed death ligand 1 (PD-L1), SOCS1 expressions, and c-Jun N-terminal kinase (JNK) activation in CRC cells were analyzed by quantitative reverse transcription polymerase chain reaction and/or Western blot. IL-4 repressed the malignant processes, yet promoted the apoptosis of CRC cells. Besides, IL-4 downregulated PD-L1 level, upregulated SOCS1 level, and restrained JNK activation in CRC cells, while enhancing CRC cell-killing effect of CD8+T cells. IL-4-induced effects on the aforementioned malignant processes of CRC cells and the killing effect of CD8+T cells toward CRC cells were all reversed when SOCS1 was knocked down in the CRC cells. IL-4 downregulates PD-L1 level via SOCS1 upregulation-induced JNK deactivation to enhance antitumor immunity in in vitro CRC. The study provides a theoretical basis for the clinical application of IL-4 in antitumor immunity in CRC.

INTERPLAY BETWEEN EPIGENETICS, SENESCENCE AND CELLULAR REDOX METABOLISM IN CANCER AND ITS THERAPEUTIC IMPLICATIONS

There is accumulating evidence indicating a close crosstalk between key molecular events regulating cell growth and proliferation, which could profoundly impact carcinogenesis and its progression. Here we focus on reviewing observations highlighting the interplay between epigenetic modifications, irreversible cell cycle arrest or senescence, and cellular redox metabolism. Epigenetic alterations, such as DNA methylation and histone modifications, dynamically influence tumour transcriptome, thereby impacting tumour phenotype, survival, growth and spread. Interestingly, the acquisition of senescent phenotype can be triggered by epigenetic changes, acting as a double-edged sword via its ability to suppress tumorigenesis or by facilitating an inflammatory milieu conducive for cancer progression. Concurrently, an aberrant redox metabolism, which is a function of the balance between reactive oxygen species (ROS) generation and intracellular anti-oxidant defences, influences signalling cascades and genomic stability in cancer cells by serving as a critical link between epigenetics and senescence. Recognizing this intricate interconnection offers a nuanced perspective for therapeutic intervention by simultaneously targeting specific epigenetic modifications, modulating senescence dynamics, and restoring redox homeostasis.

Transforming Lung Cancer Care: The Role of Transferosomes in Modern Drug Delivery.

Cancer stands as one of the leading causes of death worldwide, and lung cancer represents its most aggressive and persistent form. Traditional strategies for addressing lung cancer involve various medical therapies such as radiotherapy, chemotherapy, and surgical excision. Despite their prevalence, these conventional methods lack precision and inadvert-ently cause collateral damage to neighboring healthy cells. Recently, nanotechnology has emerged as a potential strategy for the treatment and management of lung carcinomas, bring-ing about a transformative shift in existing approaches. The primary focus of this shift is on minimizing harmful effects and improving the bioavailability of chemotherapy drugs specif-ically targeted at tumour cells. Currently, transferosome nanocarrier systems are widely em-ployed to overcome the obstacles presented by lung cancer. The utilization of transferosome-loaded therapeutic medication administration technology holds tremendous potential in reg-ulating tumour cell growth and treating lung cancer. The purpose of this study is to provide an overview and analysis of current advancements in transferosome-based drug delivery sys-tems, employing inhalational nanoparticle strategies for precise drug targeting in lung cancer management.

Metabolomics of Chinese Hamster Ovary Cells.

Increasing demand of protein biotherapeutics produced using Chinese hamster ovary (CHO) cell lines necessitates improvement in the production yield of the bioprocess. Various cell engineering, improved media formulation and process-designbased approaches utilizing the power of OMICS technologies, specifically, genomics and proteomics, have been employed; however, the potential of metabolomics largely remains unexplored. Metabolomics enables the detection, identification, and/or quantitation of small molecules, commonly known as metabolites, in and around the cells and may help to unlock the cellular molecular mechanism(s) that regulates cell growth and productivity in the bioprocess and improves cellular performance during the bioprocess. Currently, liquid chromatography (LC)/gas chromatography (CG)- coupled with mass-spectrometry (MS) and nuclear magnetic resonance (NMR) spectroscopy are the most commonly used approaches for metabolomics. Therefore, in this chapter, we have discussed the standard procedures of investigating CHO metabolites using LC/GC-MS and/or NMR-based approaches.

GCN2-SLC7A11 axis coordinates autophagy, cell cycle and apoptosis and regulates cell growth in retinoblastoma upon arginine deprivation

BackgroundArginine deprivation was previously shown to inhibit retinoblastoma cell proliferation and induce cell death in vitro. However, the mechanisms by which retinoblastoma cells respond to arginine deprivation remain to be elucidated.MethodsThe human-derived retinoblastoma cell lines Y79 and WERI-Rb-1 were subjected to arginine depletion, and the effects on inhibiting cell growth and survival were evaluated. This study investigated potential mechanisms, including autophagy, cell cycle arrest and apoptosis. Moreover, the roles of the general control nonderepressible 2 (GCN2) and mechanistic target of rapamycin complex 1 (mTORC1) signaling pathways in these processes were examined.ResultsWe demonstrated that arginine deprivation effectively inhibited the growth of retinoblastoma cells in vitro. This treatment caused an increase in the autophagic response. Additionally, prolonged arginine deprivation induced G2 cell cycle arrest and was accompanied by an increase in early apoptotic cells. Importantly, arginine depletion also induced the activation of GCN2 and the inhibition of mTOR signaling. We also discovered that the activation of SLC7A11 was regulated by GCN2 upon arginine deprivation. Knockdown of SLC7A11 rendered retinoblastoma cells partially resistant to arginine deprivation. Furthermore, we found that knockdown of GCN2 led to a decrease in the autophagic response in WERI-Rb-1 cells and arrested more cells in S phase, which was accompanied by fewer apoptotic cells. Moreover, knockdown of GCN2 induced the constant expression of ATF4 and the phosphorylation of 70S6K and 4E-BP1 regardless of arginine deprivation.ConclusionsCollectively, our findings suggest that the GCN2‒SLC7A11 axis regulates cell growth and survival upon arginine deprivation through coordinating autophagy, cell cycle arrest, and apoptosis in retinoblastoma cells. This work paves the way for the development of a novel treatment for retinoblastoma.

Structural Basis of Activity of HER2-Targeting Construct Composed of DARPin G3 and Albumin-Binding Domains.

Non-immunoglobulin-based scaffold proteins (SPs) represent one of the key therapeutic target-specific and high-affinity binders in modern medicine. Among their cellular targets are signaling receptors, in particular, receptor tyrosine kinases, whose dysfunction leads to the development of cancer and other serious diseases. Successful applications of SPs have been reported for HER receptor type 2 (HER2), a member of the human epidermal growth factor receptor family that regulates cell growth and differentiation. To extend the blood residence of SPs and prevent their high accumulation in the kidneys, these proteins are often fused with serum albumin. Promising results for HER2-binding activity were obtained for SP G3 from the DARPins (Designed Ankyrin Repeat Proteins) family fused with an albumin-binding domain (ABD). Interestingly, the detected HER2-G3 binding strongly depended on the position of the G3 module in the sequence of the constructs. Further improvement of these constructs for biomedical applications requires deciphering the molecular mechanism responsible for this effect. Here, we investigate the structural and dynamic aspects of ABD-G3 and G3-ABD chimeras using NMR spectroscopy and molecular modeling. Based on biophysical data, we come to the conclusion that extensive inter-domain contacts form in both constructs, although their binding interfaces and complex stability are somewhat different. Also, it is shown that the domain linker plays an important role-it limits the accessibility of the detected protein-protein binding sites, depending on the order of the domains in the chimeric molecules. These results create a solid structural basis for the rational design of new effective SP constructs targeting the signaling receptors in cells.