Thymosin β4 Regulates the Differentiation of Thymocytes by Controlling the Cytoskeletal Rearrangement and Mitochondrial Transfer of Thymus Epithelial Cells

The thymus is one of the most crucial immunological organs, undergoing visible age-related shrinkage. Thymic epithelial cells (TECs) play a vital role in maintaining the normal function of the thymus, and their degeneration is the primary cause of age-induced thymic devolution. Thymosin β4 (Tβ4) serves as a significant important G-actin sequestering peptide. The objective of this study was to explore whether Tβ4 influences thymocyte differentiation by regulating the cytoskeletal rearrangement and mitochondrial transfer of TECs. A combination of H&E staining, immunofluorescence, transmission electron microscopy, RT-qPCR, flow cytometry, cytoskeletal immunolabeling, and mitochondrial immunolabeling were employed to observe the effects of Tβ4 on TECs' skeleton rearrangement, mitochondrial transfer, and thymocyte differentiation. The study revealed that the Tβ4 primarily regulates the formation of microfilaments and the mitochondrial transfer of TECs, along with the formation and maturation of double-negative cells (CD4-CD8-) and CD4 single-positive cells (CD3+TCRβ+CD4+CD8-) thymocytes. This study suggests that Tβ4 plays a crucial role in thymocyte differentiation by influencing the cytoskeletal rearrangement and mitochondrial transfer of TECs. These effects may be associated with Tβ4's impact on the aggregation of F-actin. This finding opens up new avenues for research in the field of immune aging.

FXR1 regulates vascular smooth muscle cell cytoskeleton, VSMC contractility, and blood pressure by multiple mechanisms

Appropriate cytoskeletal organization is essential for vascular smooth muscle cell (VSMC) conditions such as hypertension. This study identifies FXR1 as a key protein linking cytoskeletal dynamics with mRNA stability. RNA immunoprecipitation sequencing (RIP-seq) in human VSMCs identifies that FXR1 binds to mRNA associated with cytoskeletal dynamics, and FXR1 depletion decreases their mRNA stability. FXR1 binds and regulates actin polymerization. Mass spectrometry identifies that FXR1 interacts with cytoskeletal proteins, particularly Arp2, a protein crucial for VSMC contraction, and CYFIP1, a WASP family verprolin-homologous protein (WAVE) regulatory complex (WRC) protein that links mRNA processing with actin polymerization. Depletion of FXR1 decreases the cytoskeletal processes of adhesion, migration, contraction, and GTPase activation. Using telemetry, conditional FXR1SMC/SMC mice have decreased blood pressure and an abundance of cytoskeletal-associated transcripts. This indicates that FXR1 is a muscle-enhanced WRC modulatory protein that regulates VSMC cytoskeletal dynamics by regulation of cytoskeletal mRNA stability and actin polymerization and cytoskeletal protein-protein interactions, which can regulate blood pressure.

Calcium and Sodium-mediated Dynamic Assembly of Intermediate Filament-like Protein FilP

BACKGROUND

Cytoskeletal elements play key roles in cell morphology, cell division, cell mobility, and DNA partitioning in all domains of life. The IF-like protein FilP was discovered in Streptomyces coelicolor, and it was found to perform a structurally important cytoskeletal role by providing direct mechanical support for the cells.

OBJECTIVE

This work investigated the factors influencing FilP polymerization under a variety of conditions.

METHODS

DLS technique was applied to real-time monitor the in vitro assembly process of Streptomyces coelicolor FilP.

RESULTS

The presence of small amounts of divalent cations, such as CaCl₂ or MgCl₂, enhanced the polymerization of FilP, while higher amounts suppressed its polymerization. Moreover, high concentrations of NaCl, KCl, NH₄Cl, and KNO₃ both suppressed the polymerization of FilP. EDTA was found to have a very prohibitive effect on FilP polymerization, and even the following addition of Ca²⁺ could not initiate the assembly of FilP. FilP polymerized under a range of pHs ranging from pH 6 to pH 8, while the polymerization degree was sensitive to pH. FilP formed network-like, striated filaments at neutral pH, while the filaments became more disordered or loosely packed at pH 8 and pH 6, respectively.

CONCLUSION

FilP assembly is calcium-mediated. Ca²⁺ is not only required for FilP polymerization, but also required for FilP to maintain the higher-order polymer structure. The accelerative effect of Ca²⁺ and the suppressive effect of Na⁺ persisted under a wide range of conditions, suggesting that FilP might use calcium and sodium ions as a general mechanism to mediate its polymerization process.

KIF4A drives gliomas growth by transcriptional repression of Rac1/Cdc42 to induce cytoskeletal remodeling in glioma cells

Glioma is one of the most prevalent cancers diseases in the worldwide. Kinesin superfamily protein 4 (KIF4), a KIF member classified in Kinesin 4 has been indicated as a mediator acted in tumorigenesis of human cancer. However, the mechanism of KIF4A on glioma is yet to be investigated. This study aimed to explore the potential function and mechanism of KIF4A in gliomas. We analyzed the KIF4A expression and the prognosis in gliomas patients using The Cancer Genome Atlas (TCGA) databases. KIF4A level in normal human astrocyte cell (NHA) and glioma cell lines were examined by Western blot. We studied the function of KIF4A on proliferation, migration, invasion, cell cycle in glioma cell lines using a series of in vitro and in vivo experiments. Chromatin Immunoprecipitation (ChIP) analysis was applied to searching potential KIF4A related downstream in glioma. We identified the significant up-regulated expression of KIF4A both in glioma tissues and cell. Glioma patients with elevated KIF4A expression have shorter survival. Down-regulation of KIF4A exerted inhibitory effect on cell proliferation, invasion and migration. We crucially identified that KIF4A drives gliomas growth by transcriptional repression of Rac1/Cdc42 to induce cytoskeletal remodeling in glioma cells. Knockdown of KIF4A decreased RohA, Rac1, Cdc42, Pak1 and Pak2 expression level. Our study provided a prospect that KIF4A functions as an oncogene in glioma.

Cytoskeletal and Cytoskeleton-Associated Proteins: Key Regulators of Cancer Stem Cell Properties

Cancer stem cells (CSCs) are a subpopulation of cancer cells possessing stemness characteristics that are closely associated with tumor proliferation, recurrence and resistance to therapy. Recent studies have shown that different cytoskeletal components and remodeling processes have a profound impact on the behavior of CSCs. In this review, we outline the different cytoskeletal components regulating the properties of CSCs and discuss current and ongoing therapeutic strategies targeting the cytoskeleton. Given the many challenges currently faced in targeted cancer therapy, a deeper comprehension of the molecular events involved in the interaction of the cytoskeleton and CSCs will help us identify more effective therapeutic strategies to eliminate CSCs and ultimately improve patient survival.

Inborn Errors of the Immune System Associated With Atopy

Atopic disorders, including atopic dermatitis, food and environmental allergies, and asthma, are increasingly prevalent diseases. Atopic disorders are often associated with eosinophilia, driven by T helper type 2 (Th2) immune responses, and triggered by disrupted barrier function leading to abnormal immune priming in a susceptible host. Immune deficiencies, in contrast, occur with a significantly lower incidence, but are associated with greater morbidity and mortality. A subset of atopic disorders with eosinophilia and elevated IgE are associated with monogenic inborn errors of immunity (IEI). In this review, we discuss current knowledge of IEI that are associated with atopy and the lessons these immunologic disorders provide regarding the fundamental mechanisms that regulate type 2 immunity in humans. We also discuss further mechanistic insights provided by animal models.

Modeling the Impact of Microgravity at the Cellular Level: Implications for Human Disease

A lack of gravity experienced during space flight has been shown to have profound effects on human physiology including muscle atrophy, reductions in bone density and immune function, and endocrine disorders. At present, these physiological changes present major obstacles to long-term space missions. What is not clear is which pathophysiological disruptions reflect changes at the cellular level versus changes that occur due to the impact of weightlessness on the entire body. This review focuses on current research investigating the impact of microgravity at the cellular level including cellular morphology, proliferation, and adhesion. As direct research in space is currently cost prohibitive, we describe here the use of microgravity simulators for studies at the cellular level. Such instruments provide valuable tools for cost-effective research to better discern the impact of weightlessness on cellular function. Despite recent advances in understanding the relationship between extracellular forces and cell behavior, very little is understood about cellular biology and mechanotransduction under microgravity conditions. This review will examine recent insights into the impact of simulated microgravity on cell biology and how this technology may provide new insight into advancing our understanding of mechanically driven biology and disease.