Cell Aggregation Research Articles

Structural Mapping of Protein Aggregates in Live Cells Modeling Huntington's Disease.

While protein aggregation is a hallmark of many neurodegenerative diseases, acquiring structural information on protein aggregates inside live cells remains challenging. Traditional microscopy does not provide structural information on protein systems. Routinely used fluorescent protein tags, such as Green Fluorescent Protein (GFP), might perturb native structures. Here, we report a counter-propagating mid-infrared photothermal imaging approach enabling mapping of secondary structure of protein aggregates in live cells modeling Huntington's disease. By comparing mid-infrared photothermal spectra of label-free and GFP-tagged huntingtin inclusions, we demonstrate that GFP fusions indeed perturb the secondary structure of aggregates. By implementing spectra with small spatial step for dissecting spectral features within sub-micrometer distances, we reveal that huntingtin inclusions partition into a β-sheet-rich core and a ɑ-helix-rich shell. We further demonstrate that this structural partition exists only in cells with the [RNQ+] prion state, while [rnq-] cells only carry smaller β-rich non-toxic aggregates. Collectively, our methodology has the potential to unveil detailed structural information on protein assemblies in live cells, enabling high-throughput structural screenings of macromolecular assemblies.

Ceftriaxone and MC-100093 mitigate fentanyl-induced cardiac injury in mice: Preclinical investigation of its underlying molecular mechanisms

Drug addiction is considered a worldwide concern and one of the most prevailing causes of death globally. Opioids are highly addictive drugs, and one of the most common opioids that is frequently used clinically is fentanyl. The potential harmful effects of chronic exposure to opioids on the heart are still to be elucidated. Although β-lactam antibiotics are well recognized for their ability to fight bacteria, its protective effect in the brain and liver has been reported. In this study, we hypothesize that β-lactam antibiotic, ceftriaxone, and the novel synthetic non-antibiotic β-lactam, MC-100093, are cardioprotective against fentanyl induced-cardiac injury by upregulating xCT expression. Mice were exposed to repeated low dose (0.05 mg/kg, i.p.) of fentanyl for one week and then challenged on day 9 with higher dose of fentanyl (1 mg/kg, i.p.). This study investigated cardiac histopathology and target genes and proteins in serum and cardiac tissues in mice exposed to fentanyl overdose and β-lactams. We revealed that fentanyl treatment induced cardiac damage as evidenced by elevated cardiac enzymes (troponin I). Furthermore, fentanyl treatment caused large aggregations of inflammatory cells and elevation in the areas and volumes of myocardial fibers, indicating hypertrophy and severe cardiac damage. Ceftriaxone and MC-100093 treatment, However, induced cardioprotective effects as evidenced by marked reduction in cardiac enzymes (troponin I) and changes in histopathology. Furthermore, ceftriaxone and MC-100093 treatment decreased the levels of hypertrophic genes (α-MHC & β-MHC), apoptotic (caspase-3), and inflammatory markers (IL-6 & NF-κB). This study reports for the first time the cardioprotective effect of β-lactams against fentanyl-induced cardiac injury. Further studies are greatly encouraged to completely identify the cardioprotective properties of ceftriaxone and MC-100093.

Cyanobacterial Bloom Formation by Enhanced Ecological Adaptability and Competitive Advantage of Microcystis-Non-Negligible Role of Quorum Sensing.

Microcystis-dominated cyanobacterial blooms (MCBs) frequently occur in freshwaters worldwide due to massive Microcystis colony formation and severely threaten human and ecosystem health. Quorum sensing (QS) is a direct cause of Microcystis colony formation that drives MCBs outbreak by regulating Microcystis population characteristics and behaviors. Many novel findings regarding the fundamental knowledge of the Microcystis QS phenomenon and the signaling molecules have been documented. However, little effort has been devoted to comprehensively summarizing and discussing the research progress and exploration directions of QS signaling molecules-mediated QS system in Microcystis. This review summarizes the action process of N-acyl homoserine lactones (AHLs) as major signaling molecules in Microcystis and discusses the detailed roles of AHL-mediated QS system in cellular morphology, physiological adaptability, and cell aggregation for colony formation to strengthen ecological adaptability and competitive advantage of Microcystis. The research progress on QS mechanisms in Microcystis are also summarized. Compared to other QS systems, the LuxI/LuxR-type QS system is more likely to be found in Microcystis. Also, we introduce quorum quenching (QQ), a QS-blocking process in Microcystis, to emphasize its potential as QS inhibitors in MCBs control. Finally, in response to the research deficiencies and gaps in Microcystis QS, we propose several future research directions in this field. This review deepens the understanding on Microcystis QS knowledge and provide theoretical guidance in developing strategies to monitor, control, and harness MCBs.

Legionella pneumophila cell surface RtxA release by LapD/LapG and its role in virulence

BackgroundLegionella pneumophila is a Gram-negative intracellular bacillus and is the causative agent of a severe form of pneumonia called Legionnaires’ disease which accounts for 2-9% of cases of community acquired pneumonia. It produces an extremely large protein belonging to the RTX (Repeats in ToXin) family, called RtxA, and we previously reported that RtxA is transported by a dedicated type 1 secretion system (T1SS) to the cell surface. RTX proteins have been shown to participate in the virulence or biofilm formation of various bacteria, the most studied models being the pore forming hemolysin A (HlyA) of Escherichia coli and the biofilm associated protein LapA of P. fluorescens. LapA localization depends on the enzymatic release by LapD/LapG complex activity. This study aimed to elucidate the dual localization (cell surface associated or released state) of L. pneumophila RTX protein (RtxA) and whether this released versus sequestered state of RtxA plays a role in L. pneumophila virulence.ResultsThe hereby work reveals that, in vitro, LapG periplasmic protease cleaves RtxA N-terminus in the middle of a di-alanine motif (position 108–109). Consistently, a strain lacking LapG protease maintains RtxA on the cell surface, whereas a strain lacking the c-di-GMP receptor LapD does not exhibit cell surface RtxA because of its continuous cleavage and release, as in the LapA-D-G model of Pseudomonas fluorescens. Interestingly, our data point out a key role of RtxA in enhancing the infection process of amoeba cells, regardless of its location (embedded or released); therefore, this may be the result of a secondary role of this surface protein.ConclusionsThis is the first experimental identification of the cleavage site within the RTX protein family. The primary role of RtxA in Legionella is still questionable as in many other bacterial species, hence it sounds reasonable to propose a major function in biofilm formation, promoting cell aggregation when RtxA is embedded in the outer membrane and facilitating biofilm dispersion in case of RtxA release. The role of RtxA in enhancing the infection process may be a result of its action on host cells (i.e., PDI interaction or pore-formation), and independently of its status (embedded or released).

Antioxidant and Neuroprotective Effects of Seed Oils from Trichosanthes kirilowii and T. laceribractea in Caenorhabditis elegans: A Comparative Analysis and Mechanism Study.

Excess reactive oxygen species (ROS) can accelerate amyloid β (Aβ) aggregation and tau protein hyperphosphorylation in neuron cells, which further leads to neurodegenerative diseases such as Alzheimer's disease (AD). Therefore, there is an urgent need to find natural and safe antioxidants for preventing or treating such neurodegenerative diseases. The seeds of Trichosanthes kirilowii Maxim and T. laceribractea Hayata have long been used for medicinal and edible purposes in China. However, the antioxidant and neuroprotective activities and underlying mechanisms of their seed oils still remain unclear. Herein, we examine the antioxidant and neuroprotective effects of seed oils extracted from different germplasms, T. kirilowii (YNHH and SDJN) and T. laceribractea (ZJQT and SXHZ), on ROS levels and neuroprotective activities in C. elegans. The results demonstrated that the seed oils significantly reduced the ROS levels in C. elegans by 17.03-42.74%, with T. kirilowii (YNHH and SDJN) exhibiting significantly stronger ROS scavenging abilities than T. laceribractea (ZJQT and SXHZ). The seed oils from T. kirilowii (YNHH and SDJN) alleviated the production and aggregation of Aβ and the phosphorylation and polymerization of tau, suggesting a potential neuroprotective role. Conversely, seed oils from T. laceribractea (ZJQT and SXHZ) show minimal neuroprotective effects in C. elegans. These differential outcomes might stem from distinct mechanisms underlying antioxidant and neuroprotective effects, with the ctl-2 gene implicated as pivotal in mediating the significant neuroprotective effects of seed oils from T. kirilowii (YNHH and SDJN). Our findings have provided valuable insights into the antioxidant and neuroprotective properties of T. kirilowii seed oils, paving the way for further research aimed at elucidating the underlying mechanisms and exploring their potential therapeutic applications in combating neurodegenerative diseases.

In-situ monitoring of cellular H2O2 within 3D cell clusters using conductive scaffolds

Accurately monitoring H2O2 concentrations in 3D cell clusters is challenging due to limited diffusion and rapid degradation of H2O2 in the culture medium. Despite the incorporation of three-dimensional cell culture approaches, the detection technology has largely remained as a 2D planar system. In this study, we present a versatile approach of 3D electrochemical sensing utilizing carbon nanotubes as conductive scaffolds for in-situ monitoring of H2O2 in cell clusters. These scaffolds enabled direct contact between H2O2 released from cells and the electrodes, thereby improving sensitivity and ensuring biocompatibility for cell aggregates. The scaffolds exhibited electrocatalytic behavior with a limit of detection of 6.7 nM H2O2. Additionally, the electrochemical responses of cell clusters with the scaffolds exhibited significantly higher current compared to clusters without scaffolds when stimulated with model drugs. This study underscores the potential of conductive scaffolds for real-time monitoring of H2O2 released from cell clusters in 3D microenvironments.

Quercetin Attenuates KLF4-Mediated Phenotypic Switch of VSMCs to Macrophage-like Cells in Atherosclerosis: A Critical Role for the JAK2/STAT3 Pathway.

The objective of this study was to elucidate the protective role of quercetin in atherosclerosis by examining its effect on the phenotypic switch of vascular smooth muscle cells (VSMCs) to macrophage-like cells and the underlying regulatory pathways. Aorta tissues from apolipoprotein E-deficient (ApoE KO) mice fed a high-fat diet (HFD), treated with or without 100 mg/kg/day quercetin, were analyzed for histopathological changes and molecular mechanisms. Quercetin was found to decrease the size of atherosclerotic lesions and mitigate lipid accumulation induced by HFD. Fluorescence co-localization analysis revealed a higher presence of macrophage-like vascular smooth muscle cells (VSMCs) co-localizing with phospho-Janus kinase 2 (p-JAK2), phospho-signal transducer and activator of transcription 3 (p-STAT3), and Krüppel-like factor 4 (KLF4) in regions of foam cell aggregation within aortic plaques. However, this co-localization was reduced following treatment with quercetin. Quercetin treatment effectively inhibited the KLF4-mediated phenotypic switch in oxidized low-density lipoprotein (ox-LDL)-loaded mouse aortic vascular smooth muscle cells (MOVAS), as indicated by decreased expressions of KLF4, LGALS3, CD68, and F4/80, increased expression of alpha smooth muscle actin (α-SMA), reduced intracellular fluorescence Dil-ox-LDL uptake, and decreased lipid accumulation. In contrast, APTO-253, a KLF4 activator, was found to reverse the effects of quercetin. Furthermore, AG490, a JAK2 inhibitor, effectively counteracted the ox-LDL-induced JAK2/STAT3 pathway-dependent switch to a macrophage-like phenotype and lipid accumulation in MOVAS cells. These effects were significantly mitigated by quercetin but exacerbated by coumermycin A1, a JAK2 activator. Our research illustrates that quercetin inhibits the KLF4-mediated phenotypic switch of VSMCs to macrophage-like cells and reduces atherosclerosis by suppressing the JAK2/STAT3 pathway.

Study of some components of the influence and formation of blood flow in patients with "slow flow".

"Slow flow" is one very important concept in modern fundamental and clinical biomedicine. Slow coronary flow is indicative of delayed filling of the terminal coronary artery vessels, occurring in the absence of significant coronary stenosis. This group patient of patients exhibits a high incidence of disability and represents a significant financial and material burden for the state and the healthcare system in general. The primary objective of our study was to examine patients with slow coronary flow. We studied the standard parameters recommended by the international health care system (electrocardiography (by Medica QRS-12, Germany), through the electrical activity of a patient's heart by the electrical impulses (beating) of the heart; HC1(Germany); coagulogramma by Coatron M1 (Germany), troponin by AQT 90 (Germany); general blood test we used automatic human counting device HC1(Germany). Also, we investigate the original parameters (non-standard parameters, which we use in this pilot study) that we were first studied for this diagnosis and non-standard parameters. A general blood test showed that patients with slow flow had a higher blood leukocyte count than the control group, but the amount of hemoglobin was normal, the hematocrit was much higher than in the control group, and the platelet count was close to the lower limit of clinical standards.We obtained details of blood flow by coagulation situation, such as prothrombin time, prothrombin index, international normalized ratio, activated partial thromboplastin time, thrombin time, fibrinogen, and rheological properties such as index of erythrocyte aggregability, index of erythrocyte deformability, plasma viscosity, in silico blood rheological index. Blood flow can be considered as a superposition of vortices with similar frequencies and wave vectors that change after bifurcations or other obstacles in the vascular network. These factors together determine the conditions for structuring the flow of moving blood. Disruption or alteration of these factors results in slow flow. It has been found that the speed of blood flow in the coronary arteries depends on changes in the number and function of red blood cells. Slow flow is directly influenced by the aggregation and deformation of red blood cells, their number, and plasma viscosity. Consequently, the rheological status plays a crucial role in determining blood flow and its velocity.

Delivery of Lutein by Using Modified Burdock Polysaccharide Aggregates: Preparation, Characterization, and In Vitro Release Properties.

Novel self-assembled aggregates of stearic acid (SA)-modified burdock polysaccharide (BP) for loading lutein were constructed, and the release and absorption properties of lutein in the aggregates in simulated gastrointestinal fluid were investigated. Three different degrees of substitution (DS) of SA-BPs were used to embed lutein, resulting in the encapsulation efficiency exceeding 90%. The aggregates were uniformly spherical, with a particle size range of 227-341 nm. XRD analysis revealed that lutein was present in a non-crystalline state within the aggregates. FT-IR and FS analysis demonstrated that lutein was located in the hydrophobic domains of SA-BP. The highest bioavailability of lutein in these aggregates reached 4.36 times that in the unmodified samples. These aggregates were able to remain stable in gastric juice and enhance the release rate of lutein in intestinal fluid. The transport of lutein-loaded SA-BP aggregates in Caco-2 cells competed with P-glycoprotein inhibitors, mainly promoting the transmembrane absorption of lutein through caveolae (or lipid raft)-related and clathrin-dependent endocytosis pathways. The above results suggest that SA-BP aggregates have the potential to be promising carriers for the efficient delivery of hydrophobic lutein.

HISTOMORPHOLGICAL STUDY OF THE PARATHYROID GLAND OF ONE-HUMPED CAMEL (CAMELUS ‎DROMEDARIUM)‎

Parathyroid gland of ten adult one-humped came] has been collected from the slaughter house. Glands have been fixed sectioned and stained by several procedures. The gland measured 1.2 cm in length, 0.4 cm in width and 0.25 cm thick. It differs in position from left to right side due to displacement of thyroid gland. The gland consisted of aggregate of cells arranged as solid masses, clusters, cords or strands. The parenchyma of the gland appeared with different cell density. Four cell type has been distinguished, viz., light as well as dark chief cells, oxyphils and syncytial cells.

Ion Signaling in Cell Motility and Development in Dictyostelium discoideum.

Cell-to-cell communication is fundamental to the organization and functionality of multicellular organisms. Intercellular signals orchestrate a variety of cellular responses, including gene expression and protein function changes, and contribute to the integrated functions of individual tissues. Dictyostelium discoideum is a model organism for cell-to-cell interactions mediated by chemical signals and multicellular formation mechanisms. Upon starvation, D. discoideum cells exhibit coordinated cell aggregation via cyclic adenosine 3',5'-monophosphate (cAMP) gradients and chemotaxis, which facilitates the unicellular-to-multicellular transition. During this process, the calcium signaling synchronizes with the cAMP signaling. The resulting multicellular body exhibits organized collective migration and ultimately forms a fruiting body. Various signaling molecules, such as ion signals, regulate the spatiotemporal differentiation patterns within multicellular bodies. Understanding cell-to-cell and ion signaling in Dictyostelium provides insight into general multicellular formation and differentiation processes. Exploring cell-to-cell and ion signaling enhances our understanding of the fundamental biological processes related to cell communication, coordination, and differentiation, with wide-ranging implications for developmental biology, evolutionary biology, biomedical research, and synthetic biology. In this review, I discuss the role of ion signaling in cell motility and development in D. discoideum.

PKM2 aggregation drives metabolism reprograming during aging process

While protein aggregation’s association with aging and age-related diseases is well-established, the specific proteins involved and whether dissolving them could alleviate aging remain unclear. Our research addresses this gap by uncovering the role of PKM2 aggregates in aging. We find that PKM2 forms aggregates in senescent cells and organs from aged mice, impairing its enzymatic activity and glycolytic flux, thereby driving cells into senescence. Through a rigorous two-step small molecule library screening, we identify two compounds, K35 and its analog K27, capable of dissolving PKM2 aggregates and alleviating senescence. Further experiments show that treatment with K35 and K27 not only alleviate aging-associated signatures but also extend the lifespan of naturally and prematurely aged mice. These findings provide compelling evidence for the involvement of PKM2 aggregates in inducing cellular senescence and aging phenotypes, and suggest that targeting these aggregates could be a promising strategy for anti-aging drug discovery.

Spheroids and organoids: Their implications for oral and craniofacial tissue/organ regeneration

Spheroids are spherical aggregates of cells. Normally, most of adherent cells cannot survive in suspension; however, if they adhere to each other and grow to a certain size, they can survive without attaching to the dish surface. Studies have shown that spheroid formation induces dedifferentiation and improves plasticity, proliferative capability, and differentiation capability. In particular, spontaneous spheroids represent a selective and efficient cultivation technique for somatic stem cells. Organoids are considered mini-organs composed of multiple types of cells with extracellular matrices that are maintained in three-dimensional culture. Although their culture environment is similar to that of spheroids, organoids consist of differentiated cells with fundamental tissue/organ structures similar to those of native organs. Organoids have been used for drug development, disease models, and basic biological studies. Spheroid culture has been reported for various cell types in the oral and craniofacial regions, including salivary gland epithelial cells, periodontal ligament cells, dental pulp stem cells, and oral mucosa-derived cells. For broader clinical application, it is crucial to identify treatment targets that can leverage the superior stemness of spheroids. Organoids have been developed from various organs, including taste buds, oral mucosa, teeth, and salivary glands, for basic biological studies and also with the goal to replace damaged or defective organs. The development of novel immune-tolerant cell sources is the key to the widespread clinical application of organoids in regenerative medicine. Further efforts to understand the underlying basic mechanisms of spheroids and organoids will lead to the development of safe and efficient next-generation regenerative therapies.

Evaluating the effects of temperature and agitation on biofilm formation of bacterial pathogens isolated from raw cow milk

ObjectivesTo study the effect of agitation and temperature on biofilm formation (cell aggregates embedded within a self-produced matrix) by pathogenic bacteria isolated from Raw cow milk (RCM).MethodsA 40 RCM samples were gathered from eight dairy farms in Riyadh, Saudi Arabia. After bacterial culturing and isolation, gram staining was performed, and all pathogenic, identified using standard criteria established by Food Standards Australia New Zealand (FSANZ), and non-pathogenic bacteria were identified using VITEK-2 and biochemical assays. To evaluate the effects of temperature and agitation on biofilm formation, isolated pathogenic bacteria were incubated for 24 h under the following conditions: 4 °C with no agitation (0 rpm), 15 °C with no agitation, 30 °C with no agitation, 30 °C with 60 rpm agitation, and 30 °C with 120 rpm agitation. Then, biofilms were measured using a crystal violet assay.ResultsOf the eight farm sites, three exhibited non-pathogenic bacterial contamination in their raw milk samples. Of the total of 40 raw milk samples, 15/40 (37.5%; from five farms) were contaminated with pathogenic bacteria. Overall, 346 bacteria were isolated from the 40 samples, with 329/346 (95.1%) considered as non-pathogenic and 17/346 (4.9%) as pathogenic. Most of the isolated pathogenic bacteria exhibited a significant (p < 0.01) increase in biofilm formation when grown at 30 °C compared to 4 °C and when grown with 120 rpm agitation compared to 0 rpm.ConclusionHerein, we highlight the practices of consumers in terms of transporting and storing (temperature and agitation) can significantly impact on the growth of pathogens and biofilm formation in RCM.

Clustered protocadherin cis-interactions are required for combinatorial cell–cell recognition underlying neuronal self-avoidance

In the developing human brain, only 53 stochastically expressed clustered protocadherin (cPcdh) isoforms enable neurites from individual neurons to recognize and self-avoid while simultaneously maintaining contact with neurites from other neurons. Cell assays have demonstrated that self-recognition occurs only when all cPcdh isoforms perfectly match across the cell boundary, with a single mismatch in the cPcdh expression profile interfering with recognition. It remains unclear, however, how a single mismatched isoform between neighboring cells is sufficient to block erroneous recognitions. Using systematic cell aggregation experiments, we show that abolishing cPcdh interactions on the same membrane (cis) results in a complete loss of specific combinatorial binding between cells (trans). Our computer simulations demonstrate that the organization of cPcdh in linear array oligomers, composed of cis and trans interactions, enhances self-recognition by increasing the concentration and stability of cPcdh trans complexes between the homotypic membranes. Importantly, we show that the presence of mismatched isoforms between cells drastically diminishes the concentration and stability of the trans complexes. Overall, we provide an explanation for the role of the cPcdh assembly arrangements in neuronal self/non-self-discrimination underlying neuronal self-avoidance.

Posttranscriptional Modification to Modulate Progenitor Differentiation on Heterotypic Spheroids.

Cell aggregates are widely used to study heterotypic cellular interactions during the development of vascularization in vitro. In this study, we examined heterotypic cellular spheroids made of adipose-derived stem cells and CD34+/CD31- endothelial progenitor cells induced by the transfection of miR-148b mimic for de novo induction of osteogenic differentiation and miR-210 mimic for de novo induction of endotheliogenesis, respectively. The effect of the microRNA (miRs) mimic treatment group and induction time on codifferentiation was assessed in spheroids formed of transfected cells over the course of a 4-week culture. Based on gene and protein markers of osteogenic and endotheliogenic differentiation, as well as mineralization assays, our results showed that miRs directed cell differentiation and that progenitor maturity influenced the development of heterotypic cellular regions in aggregates. Overall, the success of coculture to create a prevascularized bone model is dependent on a number of factors, particularly the induction time of differentiation before combining the multiple cell types in aggregates. The approach that has been proposed could be valuable in creating vascularized bone tissue by employing spheroids as the building blocks of more complex issues through the use of cutting-edge methods such as 3D bioprinting.

Identification and immunological characterization of genes associated with ferroptosis in Alzheimer's disease and experimental demonstration.

The incidence of Alzheimer's disease (AD) is rising globally, yet its treatment and prediction of this condition remain challenging due to the complex pathophysiological mechanisms associated with it. Consequently, the objective of the present study was to analyze and characterize the molecular mechanisms underlying ferroptosis‑related genes (FEGs) in the pathogenesis of AD, as well as to construct a prognostic model. The findings will provide new insights for the future diagnosis and treatment of AD. First, the AD dataset GSE33000 from the Gene Expression Omnibus database and the FEGs from FerrDB were obtained. Next, unsupervised cluster analysis was used to obtain the FEGs that were most relevant to AD. Subsequently, enrichment analyses were performed on the FEGs to explore biological functions. Subsequently, the role of these genes in the immune microenvironment was elucidated through CIBERSORT. Then, the optimal machine learning was selected by comparing the performance of different machine learning models. To validate the prediction efficiency, the models were validated using nomograms, calibration curves, decision curve analysis and external datasets. Furthermore, the expression of FEGs between different groups was verified using reverse transcription quantitative PCR and western blot analysis. In AD, alterations in the expression of FEGs affect the aggregation and infiltration of certain immune cells. This indicated that the occurrence of AD is strongly associated with immune infiltration. Finally, the most appropriate machine learning models were selected, and AD diagnostic models and nomograms were built. The present study provided novel insights that enhance understanding with regard to the molecular mechanism of action of FEGs in AD. Moreover, the present study provided biomarkers that may facilitate the diagnosis of AD.

Does Fibromyalgia Affect the Structure of the Dentate Gyrus?

Abstract Background The hippocampus is considered an important component of the limbic system of the brain. It is involved in memory and functional diversities. The term hippocampus typically refers to the dentate gyrus and the hippocampus proper, the cornu ammonis (CA). Fibromyalgia is known to cause memory and cognitive function impairment and is characterized by causing chronic widespread muscular pain. Aim of the Work The aim of this work was to study the possible structural and morphometric changes in rats’ hippocampal dentate gyrus induced by repeated intramuscular injections of acidic saline in the left gastrocnemius and to compare it with the control. Material and Methods Fifty-four adult female albino Swiss rats were divided into three equal groups (18 rats each): control group (I), natural saline group (II) and acidic saline group (III). Group I received no medication, group II received two i.m. injections of 100 μl saline (pH 7.4) into the left gastrocnemius muscle at day 0 and 5 respectively under sedation with halothane (2-4%), while group III received two i.m. injections of 100 μl saline (pH 4) into the left gastrocnemius muscle at day 0 and 5 respectively under sedation with halothane (2-4%). Rats of each group were further subdivided into 3 subgroups (a, b, c) 6 rats each. Rats were sacrificed by decapitation at day 7, 14, 21 from the start of experiment and their brains were excised. Results Histological examination of H&amp;E-stained sections of groups I and II showed no difference and were both considered control groups. The dentate region was formed of three laminae: the molecular, granular and polymorphic. The granular cell layer is the principal layer separating the molecular and polymorphic layers and was formed of aggregation of granular cells. They were rounded to oval with large vesicular nuclei and .prominent nucleoli The examination of the H&amp;E-stained sections of rats’ dentate gyrus granular cells (DG) appeared darkly stained with pyknotic nuclei I group III as compared to the control. Glial cells slightly increased especially among molecular and polymorphic layers. Neurofibrillary tangles and vacuolations started to appear in silver-stained sections. The neurodegenerative findings started to be more notable in subgroup (b) then became more prevalent in subgroup(c) together with the appearance of clear areas among the sub granular zone. Morphometric studies detected non-significant difference in mean area percentage of astrocytes between group I and group II subgroups. The statistical analysis demonstrated high significant difference in mean area percentage of astrocytes between control groups and acidic saline groups. Evident gliosis was confirmed in group IIIc when the astrocytes percentage areas become very highly significantly increased compared to groups I and II. Conclusion In conclusion, repeated acidic saline injection induced dentate gyrus alterations obvious but minimal at week 1 and become intense at week 3 after the first injection. This effect ended with neuronal death and gliosis.

Mechanistic Insight into Intestinal α-Synuclein Aggregation in Parkinson's Disease Using a Laser-Printed Electrochemical Sensor.

Aggregated deposits of the protein α-synuclein and depleting levels of dopamine in the brain correlate with Parkinson's disease development. Treatments often focus on replenishing dopamine in the brain; however, the brain might not be the only site requiring attention. Aggregates of α-synuclein appear to accumulate in the gut years prior to the onset of any motor symptoms. Enteroendocrine cells (specialized gut epithelial cells) may be the source of intestinal α-synuclein, as they natively express this protein. Enteroendocrine cells are constantly exposed to gut bacteria and their metabolites because they border the gut lumen. These cells also express the dopamine metabolic pathway and form synapses with vagal neurons, which innervate the gut and brain. Through this connection, Parkinson's disease pathology may originate in the gut and spread to the brain over time. Effective therapeutics to prevent this disease progression are lacking due to a limited understanding of the mechanisms by which α-synuclein aggregation occurs in the gut. We previously proposed a gut bacterial metabolic pathway responsible for the initiation of α-synuclein aggregation that is dependent on the oxidation of dopamine. Here, we develop a new tool, a laser-induced graphene-based electrochemical sensor chip, to track α-synuclein aggregation and dopamine level over time. Using these sensor chips, we evaluated diet-derived catechols dihydrocaffeic acid and caffeic acid as potential inhibitors of α-synuclein aggregation. Our results suggest that these molecules inhibit dopamine oxidation. We also found that these dietary catechols inhibit α-synuclein aggregation in STC-1 enteroendocrine cells. These findings are critical next steps to reveal new avenues for targeted therapeutics to treat Parkinson's disease, specifically in the context of functional foods that may be used to reshape the gut environment.

Following the Evolutionary Paths of Dscam1 Proteins toward Highly Specific Homophilic Interactions.

Many adhesion proteins, evolutionarily related through gene duplication, exhibit distinct and precise interaction preferences and affinities crucial for cell patterning. Yet, the evolutionary paths by which these proteins acquire new specificities and prevent cross-interactions within their family members remain unknown. To bridge this gap, this study focuses on Drosophila Down syndrome cell adhesion molecule-1 (Dscam1) proteins, which are cell adhesion proteins that have undergone extensive gene duplication. Dscam1 evolved under strong selective pressure to achieve strict homophilic recognition, essential for neuronal self-avoidance and patterning. Through a combination of phylogenetic analyses, ancestral sequence reconstruction, and cell aggregation assays, we studied the evolutionary trajectory of Dscam1 exon 4 across various insect lineages. We demonstrated that recent Dscam1 duplications in the mosquito lineage bind with strict homophilic specificities without any cross-interactions. We found that ancestral and intermediate Dscam1 isoforms maintained their homophilic binding capabilities, with some intermediate isoforms also engaging in promiscuous interactions with other paralogs. Our results highlight the robust selective pressure for homophilic specificity integral to the Dscam1 function within the process of neuronal self-avoidance. Importantly, our study suggests that the path to achieving such selective specificity does not introduce disruptive mutations that prevent self-binding but includes evolutionary intermediates that demonstrate promiscuous heterophilic interactions. Overall, these results offer insights into evolutionary strategies that underlie adhesion protein interaction specificities.