Biological Research最新文献

Background: Tau phosphorylation is a tightly regulated process that ensures proper neuronal function. Indeed, hyperphosphorylation of tau closely contributes to neuronal dysfunction leading to neurodegenerative diseases, including tauopathies, which are characterized by excessive and aberrant tau phosphorylation and cognitive decline. Therefore, it is important to understand how to regulate its phosphorylation. In this regard, the protein tyrosine phosphatase receptor delta (PTPRD) has been genetically implicated in tau pathology in humans, but the mechanisms underlying its role in tau regulation remain unclear. This study investigates the impact of Ptprd deficiency on tau phosphorylation, cognitive function, neuroinflammation, and synaptic markers in aging mice.

Results: Mice lacking Ptprd showed increased tau phosphorylation at multiple sites associated with its pathological aggregation. This effect was accompanied by the activation of the tau-related kinase Abl1, particularly in the hippocampus. Behavioral assessments revealed significant impairments in learning and memory, demonstrating the functional impact of these alterations. Moreover, Ptprd knockout mice showed increased microgliosis in both the entorhinal cortex and the hippocampus, suggesting a pro-inflammatory response. Furthermore, the synaptic protein PSD95 was also reduced in the cortex, indicating potential synaptic dysfunction.

Conclusions: The loss of Ptprd leads to increased tau phosphorylation, cognitive impairments, microgliosis, and synaptic alterations in older mice. Our findings also suggest that Ptprd plays a critical role in maintaining tau homeostasis through the Abl1 kinase. This indicates a new potential therapeutic approach for tauopathies, where PTPRD could serve a protective role against tau-related pathologies and may act as a key modulator in disease progression.

Background: The purpose of this work was to examine the fundamental mechanisms of reproductive toxicity in rat models following exposure to Fenpropathrin (FNP). Furthermore, our study explores the novel impacts of Date palm kernel extract (DPK) on these detrimental outcomes.

Methods: Thirty male Wistar rats were used in the investigation. They were split into six groups: one group received corn oil as a control; two groups received DPK at 200 mg/kg and 400 mg/kg; a group received FNP at 4.7 mg/kg; and two combination groups received DPK and FNP at 200 mg/kg and 400 mg/kg, respectively for 60 days.

Results: FNP caused oxidative stress, reduced sperm count, and impaired motility. FNP decreased the expression of the StAR gene and reduced serum testosterone levels. We assessed the histological alterations. In a dose-dependent way, the concurrent administration of DPK extract successfully decreased all the toxicological parameters.

Conclusions: When taken orally, DPK extract may protect against FNP-induced male reproductive toxicity.

Background: Nicotinamide phosphoribosyltransferase (NAMPT) is an enzyme that involves into NMN-NAD + synthesis which involves into cellular metabolism related with aging, immune function, and neurodegeneration. However, its roles in early embryo development are still unclear.

Methods: In present study we disturbed the NAMPT activity and employed immunofluorescence staining and live cell imaging to explore its roles during early embryo development.

Results: We showed that NAMPT mRNA level was stable during mouse early embryo development, and NAMPT accumulated in the nucleus of blastomeres in mouse embryos. The loss of NAMPT activity disturbed the early cleavage from zygote to 2-cell, 4-cell to morula formation in the dose-dependent manner. We found that NAMPT inhibition disrupted mitochondria function in 2-cell embryos, showing decreased mitochondria number and aberrant accumulation in the blastomeres, which further disturb mitochondrial membrane potential level and elevated ROS level in embryos, indicating the occurrence of oxidative stress. Moreover, NAMPT inhibition also increased the apoptotic index, showing with increased Annexin-V signals and apoptotic gene expression.

Conclusions: Taken together, our study provided the evidence that NAMPT was essential for the mitochondria function to control oxidative stress and apoptosis during mouse early embryo development.

Background: Aging affects the reparative potency of mesenchymal stem/stromal cells (MSCs) by diminishing their proliferation and differentiation capability; making them unsuitable for regenerative purposes. Earlier we showed that MSCs acquire the expression of CD45 as a consequence of aging, and this increased expression is associated with downregulated expression of osteogenic markers and upregulated expression of adipogenic and osteoclastogenic markers. However, whether CD45 is actively involved in the aging-mediated deregulated differentiation in the MSCs was not elucidated.

Results: In the present study, we showed that pharmacological inhibition of CD45-specific phosphatase activity in the aged MSCs restores their differentiation potential to young-like. Investigation of the molecular mechanism involved in the process showed that several regulatory kinases like p38, p44/42, Src, and GSK3β are in their dephosphorylated form in the aged MSCs, and importantly, this status gets reversed by the application of a CD45-specific PTP inhibitor. Conversely, pharmacological inhibition of these kinases in young MSCs imposes an aged-like gene expression profile on them. Additionally, we also showed that the secretome of aged MSCs affects the viability and differentiation of primary chondrocytes, and this detrimental effect is reversed by treating aged MSCs with the PTP inhibitor. Our data demonstrate that the aging-mediated expression of CD45 in MSCs alters their differentiation profile by dephosphorylating several kinases and treating the aged MSCs with a CD45 PTP activity inhibitor rejuvenates them.

Conclusions: CD45 can be used as an aging marker for mesenchymal stem cells. Alteration of CD45 phosphatase activity could have significant implications for the use of MSCs in regenerative medicine.

Objective: We aimed to explore the heterogeneities and communication properties of cardiac CMs and ECs in diabetes.

Methods: GSE213337 dataset was retrieved from NCBI Gene Expression Omnibus, containing the single-cell RNA sequencing data of hearts from the control and streptozotocin-induced diabetic mice. Cell cluster analysis was performed to identify the cell atlas. Data of CMs and ECs were extracted individually for re-cluster analysis, functional enrichment analysis and trajectory analysis. Cell communication analysis was conducted to explore the altered signals and significant ligand-receptor interactions.

Results: Eleven cell types were identified in the heart tissue. CMs were re-clustered into four subclusters, and cluster 4 was dominant in diabetic condition and enriched in cellular energy metabolism processes. ECs were re-clustered into six subclusters, and clusters 2, 4 and 5 were dominant in the diabetic condition and mainly enriched in cellular energy metabolism and lipid transport processes. The cellular communication network was altered in the diabetic heart. ECs dominated the overall signaling and notably increased the ANGPTL and SEMA4 signals in the diabetic heart. Four significant ligand-receptor pairs implicating the two signals contributed to the communication between ECs and other cell types, including Angptl1-(Itga1 + Itgb1), Angptl4-Cdh5, Angptl4-Sdc3, and Sema4a-(Nrp + Plxna2). The ligand Angptl4 engaged in ECs-CMs communication in a paracrine manner.

Conclusion: Single-cell sequencing analysis revealed heterogeneities of ECs and CMs in diabetes, Angptl4-Cdh5 and Angptl4-Sdc3 were involved in the communication between ECs and CMs in diabetes.

Fragile X Syndrome (FXS) is the most common monogenetic cause of autism and inherited intellectual disability. A key feature of FXS symptomatology is altered sensory processing greatly affecting FXS individual's life quality. Here, we use a combination of behavioral tests and slice physiology tools to study the neurophysiological alterations underlying aberrant sensory processing in the olfactory system of the FXS mouse model (Fmr1 KO). We focused on the piriform cortex (PC), since it is in this brain region where olfactory information is integrated and ultimately decoded. Using a go-no go behavioral task we have found that Fmr1 KO learn to discriminate between a rewarded and a not rewarded odorant but cannot distinguish complex odor mixtures, akin to what is found in the environment. Moreover, Fmr1 KO long-term memory is impaired compared to control mice suggesting possibly cortical processing alterations. In addition, electrophysiological data from PC layer II neurons of Fmr1 KO mice showed a hyperexcitable phenotype manifested by differences in active membrane properties and altered network connectivity. Taken together, our data suggest a possible causal link between the observed olfactory discrimination deficiencies in the Fmr1 KO mouse and the altered physiology of PC.

Background: Stem cell therapies may potentially be used in regenerative and reconstructive medicine due to their ability for self-renewal and differentiation. Stressful conditions, such as hyperglycemia, adversely affect stem cell functions, impairing their function and promoting differentiation by opposing self-renewal. The carboxyl terminus of HSP70 interacting protein (CHIP), which is a cochaperone and E3 ligase, maintains protein homeostasis and performs quality control of the cell via ubiquitylation. However, the role of CHIP in regulating stemness remains unknown.

Results: Hyperglycemia downregulated CHIP-induced p53, arrested the cell cycle at the gap (G₁) phase, and promoted the loss of stemness in WJMSCs. Quantitative real-time polymerase chain reaction (qRT-PCR), Western blotting, immunofluorescence, and cell cycle analysis showed that CHIP-overexpressing WJMSCs downregulated the expression of phosphorylated p53 and shortened its half-life while enhancing self-renewal factors. Additionally, co-IP and Western blotting revealed that CHIP promoted the ubiquitination and proteasomal degradation of hyperglycemia-induced p53 through the chaperone system.

Conclusions: CHIP may promote ubiquitin-mediated proteasomal degradation of hyperglycemia-induced p53 rescues self-renewal genes, which can maintain the long-term undifferentiated state of WJMSCs. CHIP may be an alternative therapeutic option in regenerative medicine for hyperglycemic-related complications in diabetes.

Alzheimer's disease (AD) is a neurodegenerative disorder influenced by both genetic and environmental factors. Identifying therapeutic targets and interventions remains challenging. This study utilized Mendelian Randomization (MR) to investigate causal relationships between plasma proteins, lifestyle factors, and AD, along with virtual screening to identify potential drug compounds. A two-sample MR analysis assessed associations between plasma proteins, identified through genome-wide association studies (GWAS), and AD risk. Co-localization analysis (CA) confirmed the overlap between protein expression and AD susceptibility loci, and reverse MR ruled out reverse causality. A protein-protein interaction (PPI) network was constructed to explore therapeutic targets, followed by virtual screening to identify small-molecule inhibitors for selected proteins. The analysis found significant associations between eight plasma proteins and AD, with five proteins (GSTP1, BIN1, Siglec-3, SERPINF2, and GRN) showing strong evidence of involvement in AD pathogenesis. Virtual screening identified six compounds as potential inhibitors of GSTP1 and four compounds as potential inhibitors of BIN1. Furthermore, MR analysis of lifestyle factors, such as dietary behaviors and smoking cessation, indicated they may influence AD risk through their effects on specific proteins. These findings offer novel insights into the genetic mechanisms underlying AD and highlight the potential of combining MR with virtual screening to identify therapeutic targets. The study also suggests that lifestyle modifications could offer alternative prevention and treatment strategies for AD. Future research should focus on the experimental validation of the identified compounds and further explore the mechanisms linking lifestyle factors to AD.

Background: Spinocerebellar ataxia 19/22 (SCA19/22) represents a rare autosomal dominant genetic disorder resulting in progressive ataxia and cerebellar atrophy. SCA19/22 is caused by variants in the KCND3 gene, which encodes a voltage-gated potassium channel subunit essential for cerebellar Purkinje cell function. To date, 22 variants have been reported worldwide, with incomplete functional studies.

Results: We present four Chilean and Mexican cases in whom two single-nucleotide variants were identified through whole-exome sequencing of the probands. One variant (G371R) was initially cataloged as pathogenic and the other (S357W) as likely pathogenic according to the American College of Medical Genetics and Genomics criteria. The pathogenicity of the G371R variation was confirmed by in-silico mutagenesis. Our molecular models, that include electrostatic potential analysis and algorithms to analyze the pore dimensions (HOLE), indicated that the longer side chain of the arginine narrowed the channel's selectivity filter, while the positive charge modified its surface electrostatic potential, presumably preventing potassium flux. Functional characterization of the S357W variant was performed in AD293 cells. When overexpressed, K_V4.3^S357W channels alone showed no current. Protein electrophoresis revealed that the total number of K_V4.3 channels expressed did not differ between the wild-type and mutated phenotypes, suggesting a protein trafficking malfunction. Co-expression of the KChIP2 auxiliary subunit partially rescued the potassium currents when the variant was expressed, albeit with very different biophysical characteristics, including faster inactivation vs. wild-type channels.

Conclusions: This functional characterization of two KCND3 variants associated with SCA19/22 adds new evidence for the pathogenic role of Kv4.3 loss-of-function mutations and establishes a correlation between functional dominance and clinical severity in SCA19/22.