From Natural Insulin to Designed Analogs: A Chemical Biology Exploration.

Since its discovery in 1921, insulin has been at the forefront of scientific breakthroughs. From its amino acid sequencing to the revelation of its three-dimensional structure, the progress in insulin research has spurred significant therapeutic breakthroughs. In recent years, protein engineering has introduced innovative chemical and enzymatic methods for insulin modification, fostering the development of therapeutics with tailored pharmacological profiles. Alongside these advances, the quest for self-regulated, glucose-responsive insulin remains a holy grail in the field. In this article, we highlight the pivotal role of chemical biology in driving these innovations and discuss how it continues to shape the future trajectory of insulin research.

Molecular Dynamics Simulation of the Effect of Carbon Space Lengths on the Antifouling Properties of Hydroxyalkyl Acrylamides.

Surface hydration has been proposed as the key antifouling mechanism of antifouling materials. However, molecular-level details of the structure, dynamics, and interactions of interfacial water around antifouling polymers still remain elusive. In this work, using all-atom molecular dynamics (MD) simulations, we studied four different acrylamides (AMs) for their interfacial water behaviors and their interactions with a protein, with special attention to the effect of carbon spacer lengths (CSLs) on the hydration properties of AMs. Collective MD simulation data revealed that although all four AMs displayed strong hydration, N-hydroxymethyl acrylamide (HMAA) and N-(2-hydroxyethyl)acrylamide (HEAA) with shorter CSLs displayed a longer residence time, slower self-diffusion, and lower coordination number of interfacial water molecules than N-(3-hydroxypropyl)acrylamide (HPAA) and N-(5-hydroxypentyl)-acrylamide (HPenAA) with longer CSLs. The shorter CSLs allow water molecules to form bridging hydrogen bonds with different hydrophilic groups in the same AM chain, thus enhancing the hydration capacity of AMs. Consequently, different from HPenAA, which had a weak but detectable interaction with the protein, HMAA, HEAA, and HPAA had almost zero interactions with the protein. This computational work provides a better fundamental understanding of the surface hydration and protein interaction of different AMs with subtle structural changes from structural, dynamic, and energy aspects at the atomic level, which hopefully will guide the design of new and effective nonfouling materials.

Structural Dependence of Salt-Responsive Polyzwitterionic Brushes with an Anti-Polyelectrolyte Effect.

Some polyzwitterionic brushes exhibit a strong "anti-polyelectrolyte effect" and ionic specificity that make them versatile platforms to build smart surfaces for many applications. However, the structure-property relationship of zwitterionic polymer brushes still remains to be elucidated. Herein, we aim to study the structure-dependent relationship between different zwitterionic polymers and the anti-polyelectrolyte effect. To this end, a series of polyzwitterionic brushes with different cationic moieties (e.g., imidazolium, ammonium, and pyridinium) in their monomeric units and with different carbon spacer lengths (e.g., CSL = 1, 3, and 4) between the cation and anion were designed and synthesized to form polymer brushes via the surface-initiated atom transfer radical polymerization. All zwitterionic brushes were carefully characterized for their surface morphologies, compositions, wettability, and film thicknesses by atomic force microscopy, contact angle measurement, and ellipsometry, respectively. The salt-responsiveness of all zwitterionic brushes to surface hydration and friction was further examined and compared both in water and in salt solutions with different salt concentrations and counterion types. The collective data showed that zwitterionic brushes with different cationic moieties and shorter CSLs in salt solution induced higher surface friction and lower surface hydration than those in water, exhibiting strong anti-polyelectrolyte effect salt-responsive behaviors. By tuning the CSLs, cationic moieties, and salt concentrations and types, the surface wettability can be changed from a highly hydrophobic surface (∼60°) to a highly hydrophilic surface (∼9°), while interfacial friction can be changed from ultrahigh friction (µ ≈ 4.5) to superior lubrication (µ ≈ 10-3). This work provides important structural insights into how subtle structural changes in zwitterionic polymers can yield great changes in the salt-responsive properties at the interface, which could be used for the development of smart surfaces for different applications.

Synthesis and Characterization of Ultralow Fouling Poly(N-acryloyl-glycinamide) Brushes.

The rational design of biomaterials with antifouling properties still remains a challenge, although this is important for many bench-to-bedside applications for biomedical implants, drug delivery carriers, and marine coatings. Herein, we synthesized and characterized poly(N-acryloylglycinamide) (polyNAGA) and then grafted poly(NAGA) onto Au substrate to form polymer brushes with well-controlled film stability, wettability, and thickness using surface-initiated atom transfer radical polymerization (SI-ATRP). The NAGA monomer integrates two hydrophilic amides on the side chain to enhance surface hydration, which is thought as a critical contributor to its antifouling property. The antifouling performances of poly(NAGA) brushes of different film thicknesses were then rigorously assessed and compared using protein adsorption assay from undiluted blood serum and plasma, cell-adhesive assay, and bacterial assay. The resulting poly(NAGA) brushes with a film thickness of 25-35 nm exhibited excellent in vitro antifouling ability to prevent unwanted protein adsorption (<0.3 ng/cm2) and bacterial and cell attachments up to 3 days. Molecular dynamics (MD) simulations further showed that two hydrophilic amide groups can interact with water molecules strongly to form a strong hydration layer via coordinated hydrogen bonds. This confirms a positive correlation between antifouling property and surface hydration. In line with a series of polyacrylamides and polyacrylates as antifouling materials synthesized in our lab, we propose that small structural changes in the pendent groups of polymers could largely improve the antifouling capacity, which may be used as a general design rule for developing next-generation antifouling materials.

Antagonistic Insulin Derivative Suppresses Insulin-Induced Hypoglycemia.

Insulin derivatives provide new functions that are distinctive from native insulin. We investigated insulin modifications on the C-terminal A chain with insulin receptor (IR) peptide binders and presented a full and potent IR antagonist. We prepared insulin precursors featuring a sortase A (SrtA) recognition sequence, LPETGG, at the C-terminal A chain and used a SrtA-mediated ligation method to synthesize insulin derivatives. The insulin precursor exhibits full IR agonism potency, similar to native human insulin. We explored derivatives with linear IR binding peptides attached to the insulin C-terminal A chain. One insulin derivative with an IR binder (Ins-AC-S2) can fully antagonize IR activation by insulin, as confirmed by cell-based assays. This IR antagonist suppresses insulin-induced hypoglycemia in a streptozotocin-induced diabetic rat model. This study provides a new direction toward insulin antagonist development.

Supramolecular approaches for insulin stabilization without prolonged duration of action.

Aggregation represents a significant challenge for the long-term formulation stability of insulin therapeutics. The supramolecular PEGylation of insulin with conjugates of cucurbit[7]uril and polyethylene glycol (CB[7]‒PEG) has been shown to stabilize insulin formulations by reducing aggregation propensity. Yet prolonged in vivo duration of action, arising from sustained complex formation in the subcutaneous depot, limits the application scope for meal-time insulin uses and could increase hypoglycemic risk several hours after a meal. Supramolecular affinity of CB[7] in binding the B1-Phe residue on insulin is central to supramolecular PEGylation using this approach. Accordingly, here we synthesized N-terminal acid-modified insulin analogs to reduce CB[7] interaction affinity at physiological pH and reduce the duration of action by decreasing the subcutaneous depot effect of the formulation. These insulin analogs show weak to no interaction with CB[7]‒PEG at physiological pH but demonstrate high formulation stability at reduced pH. Accordingly, N-terminal modified analogs have in vitro and in vivo bioactivity comparable to native insulin. Furthermore, in a rat model of diabetes, the acid-modified insulin formulated with CB[7]‒PEG offers a reduced duration of action compared to native insulin formulated with CB[7]‒PEG. This work extends the application of supramolecular PEGylation of insulin to achieve enhanced stability while reducing the risks arising from a subcutaneous depot effect prolonging in vivo duration of action.

Cross-seeding between Aß and SEVI indicates a pathogenic link and gender difference between alzheimer diseases and AIDS.

Amyloid-ß (Aß) and semen-derived enhancer of viral infection (SEVI) are considered as the two causative proteins for central pathogenic cause of Alzheimer's disease (AD) and HIV/AIDS, respectively. Separately, Aß-AD and SEVI-HIV/AIDS systems have been studied extensively both in fundamental research and in clinical trials. Despite significant differences between Aß-AD and SEVI-HIV/AIDS systems, they share some commonalities on amyloid and antimicrobial characteristics between Aß and SEVI, there are apparent overlaps in dysfunctional neurological symptoms between AD and HIV/AIDS. Few studies have reported a potential pathological link between Aß-AD and SEVI-HIV/AIDS at a protein level. Here, we demonstrate the cross-seeding interactions between Aß and SEVI proteins using in vitro and in vivo approaches. Cross-seeding of SEVI with Aß enabled to completely prevent Aß aggregation at sub-stoichiometric concentrations, disaggregate preformed Aß fibrils, reduce Aß-induced cell toxicity, and attenuate Aß-accumulated paralysis in transgenic AD C. elegans. This work describes a potential crosstalk between AD and HIV/AIDS via the cross-seeding between Aß and SEVI, identifies SEVI as Aß inhibitor for possible treatment or prevention of AD, and explains the role of SEVI in the gender difference in AD.

Fundamentals and exploration of aggregation-induced emission molecules for amyloid protein aggregation.

The past decade has witnessed the growing interest and advances in aggregation-induced emission (AIE) molecules as driven by their unique fluorescence/optical properties in particular sensing applications including biomolecule sensing/detection, environmental/health monitoring, cell imaging/tracking, and disease analysis/diagnosis. In sharp contrast to conventional aggregation-caused quenching (ACQ) fluorophores, AIE molecules possess intrinsic advantages for the study of disease-related protein aggregates, but such studies are still at an infant stage with much less scientific exploration. This outlook mainly aims to provide the first systematic summary of AIE-based molecules for amyloid protein aggregates associated with neurodegenerative diseases. Despite a limited number of studies on AIE-amyloid systems, we will survey recent and important developments of AIE molecules for different amyloid protein aggregates of Aß (associated with Alzheimer's disease), insulin (associated with type 2 diabetes), (α-syn, associated with Parkinson's disease), and HEWL (associated with familial lysozyme systemic amyloidosis) with a particular focus on the working principle and structural design of four types of AIE-based molecules. Finally, we will provide our views on current challenges and future directions in this emerging area. Our goal is to inspire more researchers and investment in this emerging but less explored subject, so as to advance our fundamental understanding and practical design/usages of AIE molecules for disease-related protein aggregates.

Conformational-specific self-assembled peptides as dual-mode, multi-target inhibitors and detectors for different amyloid proteins.

Prevention and detection of misfolded amyloid proteins and their ß-structure-rich aggregates are the two promising but different (pre)clinical strategies to treat and diagnose neurodegenerative diseases including Alzheimer's diseases (AD) and type II diabetes (T2D). Conventional strategies prevent the design of new pharmaceutical molecules with both amyloid inhibition and detection functions. Here, we propose a "like-interacts-like" design principle to de novo design a series of new self-assembling peptides (SAPs), enabling them to specifically and strongly interact with conformationally similar ß-sheet motifs of Aß (association with AD) and hIAPP (association with T2D). Collective in vitro experimental data from thioflavin (ThT), atomic force microscopy (AFM), circular dichroism (CD), and cell assay demonstrate that SAPs possess two integrated functions of (i) amyloid inhibition for preventing both Aß and hIAPP aggregation by 34-61% and reducing their induced cytotoxicity by 7.6-35.4% and (ii) amyloid sensing for early detection of toxic Aß and hIAPP aggregates using in-house SAP-based paper sensors and SPR sensors. The presence of both amyloid inhibition and detection in SAPs stems from strong molecular interactions between amyloid aggregates and SAPs, thus providing a new multi-target model for expanding the new therapeutic potentials of SAPs and other designs with built-in amyloid inhibition and detection functions.

A new strategy to reconcile amyloid cross-seeding and amyloid prevention in a binary system of α-synuclein fragmental peptide and hIAPP.

Amyloid cross-seeding and amyloid inhibition are two different research subjects being studied separately for different pathological purposes, in which amyloid cross-seeding targets to study the co-aggregation of different amyloid proteins and potential molecular links between different neurodegenerative diseases, while amyloid inhibition aims to design different molecules for preventing amyloid aggregation. While both amyloid cross-seeding and amyloid inhibition are critical for better understanding the pathological causes of different neurodegenerative diseases including Parkinson disease (PD) and Type 2 diabetes (T2D), less efforts have been made to reconcile the two phenomena. Herein, we proposed a new preventive strategy to demonstrate (a) the cross-seeding of octapeptide TKEQVTNV from α-synuclein (associated with PD) with hIAPP (associated with T2D) and (b) the cross-seeding-promoted hIAPP fibrillization and cross-seeding-reduced hIAPP toxicity. Collective results confirmed that TKEQVTNV can indeed cross-seed with hIAPP monomers and oligomers, not protofibrils, to form ß-structure-rich fibrils and to accelerate hIAPP fibrillization. Moreover, such cross-seeding-induced promotion effect by TKEQVTNV also rescued the pancreatic cells from hIAPP-induced cytotoxicity by increasing cell viability and reducing cell apoptosis simultaneously. This work provides a new angle to discover amyloid fragments and use them as amyloid modulators (inhibitors or promotors) to interfere with amyloid aggregation of other amyloid proteins, as well as sequence/structure basis to explore the amyloid cross-seeding between different amyloid proteins that may help explain a potential molecular talk between different neurodegenerative diseases.

Dual amyloid cross-seeding reveals steric zipper-facilitated fibrillization and pathological links between protein misfolding diseases.

Amyloid cross-seeding, as a result of direct interaction and co-aggregation between different disease-causative peptides, is considered as a main mechanism for the spread of the overlapping pathology across different cells and tissues between different protein-misfolding diseases (PMDs). Despite the biomedical significance of amyloid cross-seeding in amyloidogenesis, it remains a great challenge to discover amyloid cross-seeding systems and reveal their cross-seeding structures and mechanisms. Herein, we are the first to report that GNNQQNY - a short fragment from yeast prion protein Sup35 - can cross-seed with both amyloid-ß (Aß, associated with Alzheimer's disease) and human islet amyloid polypeptide (hIAPP, associated with type II diabetes) to form ß-structure-rich assemblies and to accelerate amyloid fibrillization. Dry, steric ß-zippers, formed by the two ß-sheets of different amyloid peptides, provide generally interactive and structural motifs to facilitate amyloid cross-seeding. The presence of different steric ß-zippers in a variety of GNNQQNY-Aß and GNNQQNY-hIAPP assemblies also explains amyloid polymorphism. In addition, alteration of steric zipper formation by single-point mutations of GNNQQNY and interactions of GNNQQNY with different Aß and hIAPP seeds leads to different amyloid cross-seeding efficiencies, further confirming the existence of cross-seeding barriers. This work offers a better structural-based understanding of amyloid cross-seeding mechanisms linked to different PMDs.

Antimicrobial α-defensins as multi-target inhibitors against amyloid formation and microbial infection.

Amyloid aggregation and microbial infection are considered as pathological risk factors for developing amyloid diseases, including Alzheimer's disease (AD), type II diabetes (T2D), Parkinson's disease (PD), and medullary thyroid carcinoma (MTC). Due to the multifactorial nature of amyloid diseases, single-target drugs and treatments have mostly failed to inhibit amyloid aggregation and microbial infection simultaneously, thus leading to marginal benefits for amyloid inhibition and medical treatments. Herein, we proposed and demonstrated a new "anti-amyloid and antimicrobial hypothesis" to discover two host-defense antimicrobial peptides of α-defensins containing ß-rich structures (human neutrophil peptide of HNP-1 and rabbit neutrophil peptide of NP-3A), which have demonstrated multi-target, sequence-independent functions to (i) prevent the aggregation and misfolding of different amyloid proteins of amyloid-ß (Aß, associated with AD), human islet amyloid polypeptide (hIAPP, associated with T2D), and human calcitonin (hCT, associated with MTC) at sub-stoichiometric concentrations, (ii) reduce amyloid-induced cell toxicity, and (iii) retain their original antimicrobial activity upon the formation of complexes with amyloid peptides. Further structural analysis showed that the sequence-independent amyloid inhibition function of α-defensins mainly stems from their cross-interactions with amyloid proteins via ß-structure interactions. The discovery of antimicrobial peptides containing ß-structures to inhibit both microbial infection and amyloid aggregation greatly expands the new therapeutic potential of antimicrobial peptides as multi-target amyloid inhibitors for better understanding pathological causes and treatments of amyloid diseases.

Machine Learning-Enabled Design and Prediction of Protein Resistance on Self-Assembled Monolayers and Beyond.

The rational design of highly antifouling materials is crucial for a wide range of fundamental research and practical applications. The immense variety and complexity of the intrinsic physicochemical properties of materials (i.e., chemical structure, hydrophobicity, charge distribution, and molecular weight) and their surface coating properties (i.e., packing density, film thickness and roughness, and chain conformation) make it challenging to rationally design antifouling materials and reveal their fundamental structure-property relationships. In this work, we developed a data-driven machine learning model, a combination of factor analysis of functional group (FAFG), Pearson analysis, random forest (RF) and artificial neural network (ANN) algorithms, and Bayesian statistics, to computationally extract structure/chemical/surface features in correlation with the antifouling activity of self-assembled monolayers (SAMs) from a self-construction data set. The resultant model demonstrates the robustness of QCV2 = 0.90 and RMSECV = 0.21 and the predictive ability of Qext2 = 0.84 and RMSEext = 0.28, determines key descriptors and functional groups important for the antifouling activity, and enables to design original antifouling SAMs using the predicted antifouling functional groups. Three computationally designed molecules were further coated onto the surfaces in different forms of SAMs and polymer brushes. The resultant coatings with negative fouling indexes exhibited strong surface resistance to protein adsorption from undiluted blood serum and plasma, validating the model predictions. The data-driven machine learning model demonstrates their design and predictive capacity for next-generation antifouling materials and surfaces, which hopefully help to accelerate the discovery and understanding of functional materials.

Repurposing a Cardiovascular Disease Drug of Cloridarol as hIAPP Inhibitor.

Accumulating evidence have shown a strong pathological correlation between cardiovascular disease (CVD) and Type II diabetes (T2D), both of which share many common risk factors (e.g., hyperglycemia, hypertension, hypercoagulability, and dyslipidemia) and mutually contribute to each other. Driven by such strong CVD-T2D correlation and marginal benefits from drug development for T2D, here we proposed to repurpose a CVD drug of cloridarol as human islet amyloid peptide (hIAPP) inhibitor against its abnormal misfolding and aggregation, which is considered as a common and critical pathological event in T2D. To this end, we investigated the inhibition activity of cloridarol on the aggregation and toxicity of hIAPP1-37 using combined experimental and computational approaches. Collective experimental data from ThT, AFM, and CD demonstrated the inhibition ability of cloridarol to prevent hIAPP aggregation from its monomeric and oligomeric states, leading to the overall reduction of hIAPP fibrils up to 57% at optimal conditions. MTT and LDH cell assays also showed that cloridarol can also effectively increase cell viability by 15% and decrease cell apoptosis by 28%, confirming its protection of islet ß-cells from hIAPP-induced cell toxicity. Furthermore, comparative molecular dynamics simulations revealed that cloridarol was preferentially bound to the C-terminal ß-sheet region of hIAPP oligomers through a combination of hydrophobic interactions, π-π stacking, and hydrogen bonding. Such multiple site bindings allowed cloridarol to disturb hIAPP structures, reduce ß-sheet content, and block the lateral association pathway of hIAPP aggregates, thus explaining experimental findings. Different from other single-target hIAPP inhibitors, cloridarol is unique in that it works as both a CVD drug and hIAPP inhibitor, which can be used as a viable structural template (especially for benzofuran) for the further development of cloridarol-based or benzofuran-based inhibitors of amyloid proteins.

Design principles and fundamental understanding of biosensors for amyloid-ß detection.

Alzheimer's disease (AD), as an age-related, progressive neurodegenerative disease, poses substantial challenges and burdens on public health and disease research. While significant research, investment, and progress have been made for the better understanding of pathological mechanisms and risk factors of AD, all clinical trials for AD treatment and diagnostics have failed so far. Since early and accurate diagnostics of AD is key to AD prevention and treatment, the development of probes for AD-related biomarkers is highly important but challenging for AD diagnosis. In this review, emerging evidence highlights the importance of the Aß cascade hypothesis and indicates a significant role of Aß and its aggregates as biomarkers in the pathogenesis of AD; we present an up-to-date summary on Aß-based biosensor systems. Four typical biosensor systems for Aß detection and representative examples from each type of biosensor are carefully selected and discussed in terms of their sensing strategies, materials, and mechanisms. Finally, we address the remaining challenges and opportunities for the development of future sensing platforms for Aß detection and Aß-based diagnostics of AD.

Introduction and Fundamentals of Human Islet Amyloid Polypeptide Inhibitors.

Type 2 diabetes (T2D) is a common protein misfolding disease (PMD), and its pathogenesis is considered to be tightly associated with the aggregation of the disease-causative hIAPP (or amylin). Numerous studies have shown a possible pathological link between hIAPP aggregation and ß-cell death; thus, different-level strategies from basic research to clinical bench applications have been applied to discover and design different types of inhibitors for preventing hIAPP aggregation and toxicity. This review surveys recent and important advances of hIAPP aggregation inhibitors in the context of amyloid aggregation, toxicity, and inhibition. Many hIAPP inhibitors have been explored to exert different inhibitory functions on hIAPP aggregation via different pathways. A further overview of molecular simulations of inhibitor-hIAPP systems highlights some consensus binding sequences and structures of hIAPP for different inhibitors, which provide molecular insights into well-defined binding targets and binding-induced inhibition mechanisms for structural-based design of hIAPP inhibitors. In a broader view, while anti-aggregation inhibitors hold substantial promise in the prevention of PMDs, many challenges still remain and need to be addressed for advancing our fundamental understanding of amyloid aggregation and practical design of clinically relevant inhibitors to treat PMDs.

Micro- and macroscopically structured zwitterionic polymers with ultralow fouling property.

HYPOTHESIS: Polyzwitterions as a promising class of materials are often used to construct antifouling surfaces with optimized conformation and compositions for a wide variety of antifouling applications. While numerous zwitterionic polymers have been identified for their antifouling capacity, the exact relationship among molecular structure, surface hydration property, and antifouling performance of zwitterionic polymers at different scales still remains elusive. EXPERIMENTS: we first designed and synthesized a new zwitterionic monomer of 3-(4-(methacryloyloxy)-1-methylpiperidin-1-ium-1-yl)-propane-1-sulfonate (MAMPS), then used MAMPS monomers to fabricate into homogenous polymer brushes on Au substrate using SI-ATRP and heterogeneous double-network (DN) hydrogels combining with Agar network via one-pot, heating-cooling-photopolymerization method, and finally evaluated their antifouling ability to resist the adsorption of protein/cell/bacteria on the two different polymer forms at microscopic and macroscopic scales. FINDINGS: For microscopic polyMAMPS brushes, they exhibited excellent resistance to nonspecific protein adsorption from both undiluted blood serum/plasma (0.3-5 ng/cm2), cell adhesion up to 3 days, and clinically relevant bacterial attachment for 72 h at the optimal film thicknesses of 20-40 nm. For macroscopic Agar/polyMAMPS DN hydrogels, they also exhibited approximately 96% less protein adhesion than tissue culture polystyrene (TCPS). Different structured materials consisting of polyMAMPS at both micro- and macro-scales demonstrate its excellent, intrinsic antifouling property, which could be related to their highly water binding character of zwitterionic groups. PolyMAMPS materials, alternative to commonly used poly(sulfobetaine methacrylate) (polySBMA) and poly(carboxybetaine methacrylate) (polyCBMA) zwitterions, hold great promise for antifouling designs and applications.

Molecular Dynamics Simulations of Cholesterol Effects on the Interaction of hIAPP with Lipid Bilayer.

Fundamental understanding of specific interactions of human islet amyloid polypeptide (hIAPP) with cell membrane is critical for elucidating the underlying pathogenesis of type II diabetes mellitus (T2DM). Membrane cholesterol is known to regulate membrane functions and properties, but its exact role in driving hIAPP-membrane interactions still remains controversial. In this work, we computationally investigated the concentration effect of cholesterol on the adsorption, orientation, and surface interaction of hIAPP oligomers on POPC bilayers containing different amounts of cholesterol (χ = 0, 20, and 40 mol %). Collective MD simulations consistently showed that an increased cholesterol level modulated the structure and dynamics of POPC bilayer, leading to an increase of bilayer thickness, lipid packing order, and surface hydrophobicity but a decrease of lipid mobility. Cholesterol-induced bilayer changes further caused hIAPP oligomer to more preferentially bind to POPC bilayer in the presence of cholesterol via C-terminal residues, in contrast to weak or no binding of hIAPP oligomer on pure POPC bilayers. The cholesterol-enhanced hIAPP-membrane binding is mainly contributed by electrostatic interactions between C-terminal residues and lipid head groups, which may explain the rapid adsorption and aggregation of hIAPP in the presence of cholesterol in cell membranes. This computational work provides some insights into drug development and therapeutic strategies for T2DM by considering cholesterol effects.

From design to applications of stimuli-responsive hydrogel strain sensors.

Stimuli-responsive hydrogel strain sensors that synergize the advantages of both soft-wet hydrogels and smart functional materials have attracted rapidly increasing interest for exploring the opportunities from material design principles to emerging applications in electronic skins, health monitors, and human-machine interfaces. Stimuli-responsive hydrogel strain sensors possess smart and on-demand ability to specifically recognize various external stimuli and convert them into strain-induced mechanical, thermal, optical, and electrical signals. This review presents an up-to-date summary over the past five years on hydrogel strain sensors from different aspects, including material designs, gelation/fabrication methods, stimuli-responsive principles, and sensing performance. Hydrogel strain sensors are classified into five major categories based on the nature of the stimuli, and representative examples from each category are carefully selected and discussed in terms of structures, response mechanisms, and potential medical applications. Finally, current challenges and future perspectives of hydrogel strain sensors are tentatively proposed to stimulate more and better research in this emerging field.

Identification of key genes involved in the metastasis of clear cell renal cell carcinoma.

Clear cell renal cell carcinoma (ccRCC) is the most common and lethal renal malignant tumor in adults. The aim of the present study was to identify the key genes involved in ccRCC metastasis. Expression profiling data for ccRCC patients with metastasis and without metastasis were obtained from The Cancer Genome Atlas database. The datasets were used to identify differentially expressed genes (DEGs) between the metastasis group and the non-metastasis group using the DESeq2 package. Function enrichment analyses of DEGs were performed. The protein-protein interaction (PPI) network was constructed and analyzed using the Search Tool for the Retrieval of Interacting Genes and Cytoscape for further analysis of the identified hub genes. A total of 472 DEGs were identified, including 247 that were upregulated and 225 that were downregulated in the metastasis group. Gene Ontology enrichment analysis revealed that DEGs were mainly enriched in cell transmembrane movement and mitotic cell cycle process. Kyoto Encyclopedia of Genes Genomes pathway analysis revealed that the DEGs were mainly involved in the 'cell cycle' (hsa04110), 'collecting duct acid secretion' (hsa04966), 'complement and coagulation cascades' (hsa04610) and 'aldosterone-regulated sodium reabsorption' (hsa04960) pathways. Using the PPI network, 35 hub genes were identified, and the majority of them were upregulated in ccRCC tissue compared with normal kidney tissue. The expression levels of certain hub genes (CDKN3, TPX2, BUB1B, CDCA8, UBE2C, NDC80, RRM2, NCAPG, NCAPH, PTTG1, FAM64A, ANLN, KIF4A, CEP55, CENPF, KIF20A, ASPM and HJURP) were significantly associated with overall survival and recurrence-free survival in ccRCC. The present study has identified key genes associated with the metastasis of ccRCC.