Pleckstrin Homology [PH] domain, structure, mechanism, and contribution to human disease

The Role of PHLDA3 in Cancer Progression and Its Potential as a Therapeutic Target

Pleckstrin homology-like domain family A, member 3 (PHLDA3) is a p53-regulated tumor suppressor protein that suppresses AKT-mediated survival and oncogenic signaling. The PHLDA3 gene has garnered significant attention due to its multifaceted roles in tumorigenesis, metastasis, and invasion. This review explores the complex interactions between PHLDA3 and key cellular processes involved in cancer, emphasizing its regulatory mechanisms and clinical relevance. PHLDA3 has been found to be a critical regulator of metastatic pathways, particularly through its influence on the epithelial-mesenchymal transition (EMT) and in cellular invasion. Its interactions with pivotal signaling pathways, such as the Phosphoinositide 3-kinases/Protein kinase B (PI3K/AKT), p53, and Wnt/β-catenin pathways, highlight its multifunctional roles in various cancer types. Additionally, we discuss the potential of PHLDA3 as both a prognostic biomarker and a therapeutic target, offering new insights into its potential in treating advanced-stage malignancies. This review provides a detailed analysis of the role of PHLDA3 in cancer progression, including metastasis and invasion, underscoring its therapeutic potential.

In silico discovery of a novel potential allosteric PI3Kα inhibitor incorporating 2-oxopropyl urea targeting head and neck squamous cell carcinoma

Head and neck squamous cell carcinoma (HNSCC) is the most common head and neck cancer and highly aggressive and heterogeneous. Targeted therapy is still the main treatment method used in clinic due to lower side effect and personalized medication. In order to discover novel and effective drugs with low side effect against HNSCC, we analyzed the genes related to HNSCC, and found that PIK3CA was highly expressed in tumor tissues and often experienced mutations, leading to excessive activation of phosphoinositide 3-kinase alpha (PI3Kα), promoting the development of HNSCC. The allosteric PI3Kα inhibitor STX-478 inhibits the growth of tumor with hotspot mutations in PI3Kα and shows prominent efficacy on the treatment of human HNSCC xenografts without displaying the metabolic dysfunction observed in Alpelisib. These mutations open the allosteric site more readily, increasing the selectivity of STX-478 for mutant PI3Kα. STX-478 cleverly avoids the side effect of ATP competitive PI3Kα inhibitors. So, the structure of STX-478 was optimized based on the interaction mechanism between STX-478 and PI3Kα. Then, virtual screening, binding mode research, target verification, physical and chemical properties, pharmacokinetic properties and stabilities of ligand-PI3Kα complexes were evaluated by computer technologies (scaffold hopping, cdocker, SuperPred, SwissTarget prediction, Lipinski's rule of five, ADMET and MD simulation). Finally, J-53 (2-oxopropyl urea compound) with excellent properties was selected. J-53 not only formed H-bonds with key amino acids, but its unique -C(O)CH3 could also form H-bonds with ILE1019, making it more stably bound to PI3Kα and contributing to its activity. After the SciFinder verification, J-53 with novel structure had the value of further study. This study suggested that J-53 could be used as potential inhibitors of PI3Kα, and provides valuable information for the subsequent drug discovery of allosteric PI3Kα inhibitors.

Small Molecule Modulator of the mTORC2 Pathway Discovered from a DEL Library Designed to Bind to Pleckstrin Homology Domains

Pleckstrin homology (PH) domains are structural motifs critical for cellular processes, such as signal transduction and cytoskeletal organization. Due to their involvement in various diseases, PH domains are promising therapeutic targets, yet their highly charged and hydrophobic binding sites are not ideal for traditional small drugs. In this study, we designed a DNA-encoded library (DEL) mimicking phospholipids to identify novel modulators targeting PH domains with uncharted chemical properties. Screening against several PH domains led to the discovery of 2DII, a small molecule that selectively binds to mSin1PH. This compound can modulate mTORC2 activity by impairing mTORC2's membrane interactions, resulting in reduced AKT1 phosphorylation. A micromapping via Dexter energy transfer based on 2DII bearing an iridium catalyst (2DII-Ir), along with a biotin-diazirine small molecule was used for target identification by proteomics, which confirmed mSin1 as the primary intracellular target of 2DII, demonstrating its potential for selective mTORC2 pathway modulation. These findings introduce a novel strategy for targeting PH domains and provide a foundation for the development of therapeutic interventions that modulate PH-domain-dependent signaling pathways.

The Effects of Viral Structural Proteins on Acidic Phospholipids in Host Membranes

Enveloped viruses rely on host membranes for trafficking and assembly. A substantial body of literature published over the years supports the involvement of cellular membrane lipids in the enveloped virus assembly processes. In particular, the knowledge regarding the relationship between viral structural proteins and acidic phospholipids has been steadily increasing in recent years. In this review, we will briefly review the cellular functions of plasma membrane-associated acidic phospholipids and the mechanisms that regulate their local distribution within this membrane. We will then explore the interplay between viruses and the plasma membrane acidic phospholipids in the context of the assembly process for two enveloped viruses, the influenza A virus (IAV) and the human immunodeficiency virus type 1 (HIV-1). Among the proteins encoded by these viruses, three viral structural proteins, IAV hemagglutinin (HA), IAV matrix protein-1 (M1), and HIV-1 Gag protein, are known to interact with acidic phospholipids, phosphatidylserine and/or phosphatidylinositol (4,5)-bisphosphate. These interactions regulate the localization of the viral proteins to and/or within the plasma membrane and likely facilitate the clustering of the proteins. On the other hand, these viral proteins, via their ability to multimerize, can also alter the distribution of the lipids and may induce acidic-lipid-enriched membrane domains. We will discuss the potential significance of these interactions in the virus assembly process and the property of the progeny virions. Finally, we will outline key outstanding questions that need to be answered for a better understanding of the relationships between enveloped virus assembly and acidic phospholipids.

Axon guidance genes are regulated by TDP-43 and RGNEF through long-intron removal

Rho guanine nucleotide exchange factor (RGNEF) is a guanine nucleotide exchange factor (GEF) mainly involved in regulating the activity of Rho-family GTPases. It is a bi-functional protein, acting both as a guanine exchange factor and as an RNA-binding protein. RGNEF is known to act as a destabilizing factor of neurofilament light chain RNA (NEFL) and it could potentially contribute to their sequestration in nuclear cytoplasmic inclusions. Most importantly, RGNEF inclusions in the spinal motor neurons of ALS patients have been shown to co-localize with inclusions of TDP-43, the major well-known RNA-binding protein aggregating in the brain and spinal cord of human patients. Therefore, it can be hypothesized that loss-of-function of both proteins following aggregation may contribute to motor neuron death/survival in ALS patients. To further characterize their relationship, we have compared the transcriptomic profiles of neuronal cells depleted of TDP-43 and RGNEF and show that these two factors predominantly act in an antagonistic manner when regulating the expression of axon guidance genes. From a mechanistic point of view, our experiments show that the effect of these genes on the processivity of long introns can explain their mode of action. Taken together, our results show that loss-of-function of factors co-aggregating with TDP-43 can potentially affect the expression of commonly regulated neuronal genes in a very significant manner, potentially acting as disease modifiers. This finding further highlights that neurodegenerative processes at the RNA level are the result of combinatorial interactions between different RNA-binding factors that can be co-aggregated in neuronal cells. A deeper understanding of these complex scenarios may lead to a better understanding of pathogenic mechanisms occurring in patients, where more than one specific protein may be aggregating in their neurons.

Deep insights into the mechanism of isorhamnetin's anti-motion sickness effect based on photoshoproteomics

Isorhamnetin has recently been found to exhibit a remarkable anti-motion sickness effect, yet the underlying mechanism is still unclear. Herein, network pharmacology was employed to conduct a preliminary analysis on the possible biological processes involved. Results showed that common targets were localized in membranes, mitochondria, and glutamatergic synapses. In particular, protein phosphorylation, protein serine/threonine/tyrosinase activity and signal transduction might play a role in isorhamnetin's anti-motion sickness effect. Thus, mice phosphoproteomics analysis was further performed to explore the phosphorylated protein changes in the motion sickness process. Results showed that differentially phosphorylated proteins have an effect on postsynaptic density, glutamatergic synapses and other sites and are involved in various neurodegenerative disease pathways, endocytic pathways, cAMP signaling pathways and MAPK signaling pathways. Two key differentially phosphorylated proteins in glutamatergic synapses, namely, DLGAP and EPS8, might play key roles in isorhamnetin's anti-motion sickness process. The final molecular experimental verification results from qRT-PCR and western blot analyses indicated that isorhamnetin firstly regulates glutamatergic synapses and then reduces the excitability of the vestibular nucleus through inhibiting the NMDAR1/CaMKII/CREB signaling pathway, ultimately alleviating a series of symptoms of motion sickness in mice. The findings of this study provide valuable insights and a useful theoretical basis for the application of isorhamnetin as a new anti-motion sickness food ingredient.

Insights into the role of sterol metabolism in antifungal drug resistance: a mini-review

Sterols are essential for eukaryotic cells and are crucial in cellular membranes' structure, function, fluidity, permeability, adaptability to environmental stressors, and host-pathogen interactions. Fungal sterol, such as ergosterol metabolism, involves several organelles, including the mitochondria, lipid droplets, endoplasmic reticulum, and peroxisomes that can be regulated mainly by feedback mechanisms and transcriptionally. The majority of sterol transport in yeast occurs via non-vesicular transport pathways mediated by lipid transfer proteins, which determine the quantity of sterol present in the cell membrane. Pathogenic fungi Candida, Aspergillus, and Cryptococcus species can cause a range of superficial to potentially fatal systemic and invasive infections that are more common in immunocompromised patients. There is a significant risk of morbidity and mortality from these infections, which are very difficult to cure. Several antifungal drugs with different modes of action have received clinical approval to treat fungal infections. Antifungal drugs targeting the ergosterol biosynthesis pathway are well-known for their antifungal activity; however, an imbalance in the regulation and transport of ergosterol could lead to resistance to antifungal therapy. This study summarizes how fungal sterol metabolism and regulation can modulate sterol-targeting antifungal drug resistance.

Novel Mutations in AKT1 Gene in Prostate Cancer Patients in Jordan

The AKT1 oncogene is related to various cancers due to its critical role in the PIC3CA/AKT1 pathway; however, most of the studies screened the hotspot mutation AKT1 (E17K) with various incidences. Low frequency or lack of AKT1 (E17K) mutation was reported in prostate cancer (PC) patients. This study aims to explore genetic alterations in the AKT1 PH domain by extending the sequencing to include AKT1 gene exons 3 and 4. Genomic DNA was extracted from 84 Formalin-Fixed Paraffin-Embedded samples of PC patients in Jordan, and then subjected to PCR and sequencing for the targeted exons. This study revealed the presence of two novel mutations (N53Y and Q59K) and a high frequency of mutations in exon 4, with a lack of mutations in the E17K hotspot. Nine missense and two synonymous mutations were detected in exon 4 (Phe27Tyr, Phe27Leu, Ala58Thr, Ser56Phe, Arg41Trp, Phe35Leu, Asp32Glu, Phe35Tyr, and Gln43Lys) and (Ser56 and Glu40), respectively. Two synonymous mutations were detected in exon 3 (Leu12 and Ser2). It is concluded that there is a high frequency of AKT1 mutation in PC patients in Jordan with two novel missense mutations in the Pleckstrin homology (PH) domain. E17K hotspot mutation was not detected in any tested samples, which underlined the significant role of mutations in other AKT1 exons in PC development.

Oral Cannabidiol Treatment Is Associated with an Anti-Inflammatory Gene Expression Signature in Myeloid Cells of People Living with HIV

Introduction: HIV-related comorbidities appear to be related to chronic inflammation, a condition characterizing people living with HIV (PLWH). Prior work indicates that cannabidiol (CBD) might reduce inflammation; however, the genetics underpinning of this effect are not well investigated. Our main objective is to detect gene expression alterations in human peripheral blood mononuclear cells (PBMCs) from PLWH after at least 1 month of CBD treatment. Materials and Methods: We analyzed ∼41,000 PBMCs from three PLWH at baseline and after CBD treatment (27-60 days) through single-cell RNA sequencing. Results: We obtained a coherent signature, characterized by an anti-inflammatory activity, of differentially expressed genes in myeloid cells. Conclusions: Our study shows how CBD is associated with alterations of gene expression in myeloid cells after CBD treatment. Clinical Trial Registration: NCT05209867.

Mechanistic and therapeutic perspectives of non-coding RNA-modulated apoptotic signaling in diabetic retinopathy

Diabetic retinopathy (DR), a significant and vision-endangering complication associated with diabetes mellitus, constitutes a substantial portion of acquired instances of preventable blindness. The progression of DR appears to prominently feature the loss of retinal cells, encompassing neural retinal cells, pericytes, and endothelial cells. Therefore, mitigating the apoptosis of retinal cells in DR could potentially enhance the therapeutic approach for managing the condition by suppressing retinal vascular leakage. Recent advancements have highlighted the crucial regulatory roles played by non-coding RNAs (ncRNAs) in diverse biological processes. Recent advancements have highlighted that non-coding RNAs (ncRNAs), including microRNAs (miRNAs), circular RNAs (circRNAs), and long non-coding RNAs (lncRNAs), act as central regulators in a wide array of biogenesis and biological functions, exerting control over gene expression associated with histogenesis and cellular differentiation within ocular tissues. Abnormal expression and activity of ncRNAs has been linked to the regulation of diverse cellular functions such as apoptosis, and proliferation. This implies a potential involvement of ncRNAs in the development of DR. Notably, ncRNAs and apoptosis exhibit reciprocal regulatory interactions, jointly influencing the destiny of retinal cells. Consequently, a thorough investigation into the complex relationship between apoptosis and ncRNAs is crucial for developing effective therapeutic and preventative strategies for DR. This review provides a fundamental comprehension of the apoptotic signaling pathways associated with DR. It then delves into the mutual relationship between apoptosis and ncRNAs in the context of DR pathogenesis. This study advances our understanding of the pathophysiology of DR and paves the way for the development of novel therapeutic strategies.

Membrane Epilipidome-Lipid Modifications, Their Dynamics, and Functional Significance

Lipids are characterized by extremely high structural diversity translated into a wide range of physicochemical properties. As such, lipids are vital for many different functions including organization of cellular and organelle membranes, control of cellular and organismal energy metabolism, as well as mediating multiple signaling pathways. To maintain the lipid chemical diversity and to achieve rapid lipid remodeling required for the responsiveness and adaptability of cellular membranes, living systems make use of a network of chemical modifications of already existing lipids that complement the rather slow biosynthetic pathways. Similarly to biopolymers, which can be modified epigenetically and posttranscriptionally (for nucleic acids) or posttranslationally (for proteins), lipids can also undergo chemical alterations through oxygenation, nitration, phosphorylation, glycosylation, etc. In this way, an expanded collective of modified lipids that we term the "epilipidome," provides the ultimate level of complexity to biological membranes and delivers a battery of active small-molecule compounds for numerous regulatory processes. As many lipid modifications are tightly controlled and often occur in response to extra- and intracellular stimuli at defined locations, the emergence of the epilipidome greatly contributes to the spatial and temporal compartmentalization of diverse cellular processes. Accordingly, epilipid modifications are observed in all living organisms and are among the most consistent prerequisites for complex life.

Linking phosphoinositide function to mitosis

Phosphoinositides (PtdIns) are a family of differentially phosphorylated lipid second messengers localized to the cytoplasmic leaflet of both plasma and intracellular membranes. Kinases and phosphatases can selectively modify the PtdIns composition of different cellular compartments, leading to the recruitment of specific binding proteins, which control cellular homeostasis and proliferation. Thus, while PtdIns affect cell growth and survival during interphase, they are also emerging as key drivers in multiple temporally defined membrane remodeling events of mitosis, like cell rounding, spindle orientation, cytokinesis, and abscission. In this review, we summarize and discuss what is known about PtdIns function during mitosis and how alterations in the production and removal of PtdIns can interfere with proper cell division.

Multiomics Analysis of the PHLDA Gene Family in Different Cancers and Their Clinical Prognostic Value

The PHLDA (pleckstrin homology-like domain family) gene family is popularly known as a potential biomarker for cancer identification, and members of the PHLDA family have become considered potentially viable targets for cancer treatments. The PHLDA gene family consists of PHLDA1, PHLDA2, and PHLDA3. The predictive significance of PHLDA genes in cancer remains unclear. To determine the role of pleckstrin as a prognostic biomarker in human cancers, we conducted a systematic multiomics investigation. Through various survival analyses, pleckstrin expression was evaluated, and their predictive significance in human tumors was discovered using a variety of online platforms. By analyzing the protein-protein interactions, we also chose a collection of well-known functional protein partners for pleckstrin. Investigations were also carried out on the relationship between pleckstrins and other cancers regarding mutations and copy number alterations. The cumulative impact of pleckstrin and their associated genes on various cancers, Gene Ontology (GO), and pathway analyses were used for their evaluation. Thus, the expression profiles of PHLDA family members and their prognosis in various cancers may be revealed by this study. During this multiomics analysis, we found that among the PHLDA family, PHLDA1 may be a therapeutic target for several cancers, including kidney, colon, and brain cancer, while PHLDA2 can be a therapeutic target for cancers of the colon, esophagus, and pancreas. Additionally, PHLDA3 may be a useful therapeutic target for ovarian, renal, and gastric cancer.

Mining oomycete proteomes for phosphatome leads to the identification of specific expanded phosphatases in oomycetes

Phosphatases are important regulators of protein phosphorylation and various cellular processes, and they serve as counterparts to kinases. In this study, our comprehensive analysis of oomycete complete proteomes unveiled the presence of approximately 3833 phosphatases, with most species estimated to have between 100 and 300 putative phosphatases. Further investigation of these phosphatases revealed a significant increase in protein serine/threonine phosphatases (PSP) within oomycetes. In particular, we extensively studied the metallo-dependent protein phosphatase (PPM) within the PSP family in the model oomycete Phytophthora sojae. Our results showed notable differences in the expression patterns of PPMs throughout 10 life stages of P. sojae, indicating their vital roles in various stages of oomycete pathogens. Moreover, we identified 29 PPMs in P. sojae, and eight of them possessed accessory domains in addition to phosphate domains. We investigated the biological function of one PPM protein with an extra PH domain (PPM1); this protein exhibited high expression levels in both asexual developmental and infectious stages. Our analysis confirmed that PPM1 is indeed an active protein phosphatase, and its accessory domain does not affect its phosphatase activity. To delve further into its function, we generated knockout mutants of PPM1 and validated its essential roles in mycelial growth, sporangia and oospore production, as well as infectious stages. To the best of our knowledge, this study provides the first comprehensive inventory of phosphatases in oomycetes and identifies an important phosphatase within the expanded serine/threonine phosphatase group in oomycetes.

8-Aza Quinazolines as Brain Penetrant SOS1 Inhibitors for Treating Cancer

Provided herein are 8-aza quinazolines as brain-penetrant SOS1 inhibitors, pharmaceutical compositions, use of such compounds in treating cancer, and processes for preparing such compounds.