The tubulin code and its role in controlling microtubule properties and functions

Human induced pluripotent stem cell-derived therapies for regeneration after central nervous system injury

In recent years, the progression of stem cell therapies has shown great promise in advancing the nascent field of regenerative medicine. Considering the non-regenerative nature of the mature central nervous system, the concept that "blank" cells could be reprogrammed and functionally integrated into host neural networks remained intriguing. Previous work has also demonstrated the ability of such cells to stimulate intrinsic growth programs in post-mitotic cells, such as neurons. While embryonic stem cells demonstrated great potential in treating central nervous system pathologies, ethical and technical concerns remained. These barriers, along with the clear necessity for this type of treatment, ultimately prompted the advent of induced pluripotent stem cells. The advantage of pluripotent cells in central nervous system regeneration is multifaceted, permitting differentiation into neural stem cells, neural progenitor cells, glia, and various neuronal subpopulations. The precise spatiotemporal application of extrinsic growth factors in vitro, in addition to microenvironmental signaling in vivo, influences the efficiency of this directed differentiation. While the pluri- or multipotency of these cells is appealing, it also poses the risk of unregulated differentiation and teratoma formation. Cells of the neuroectodermal lineage, such as neuronal subpopulations and glia, have been explored with varying degrees of success. Although the risk of cancer or teratoma formation is greatly reduced, each subpopulation varies in effectiveness and is influenced by a myriad of factors, such as the timing of the transplant, pathology type, and the ratio of accompanying progenitor cells. Furthermore, successful transplantation requires innovative approaches to develop delivery vectors that can mitigate cell death and support integration. Lastly, host immune responses to allogeneic grafts must be thoroughly characterized and further developed to reduce the need for immunosuppression. Translation to a clinical setting will involve careful consideration when assessing both physiologic and functional outcomes. This review will highlight both successes and challenges faced when using human induced pluripotent stem cell-derived cell transplantation therapies to promote endogenous regeneration.

Identification and characterization of tubulin as Ga(III)-binding protein in T24 cells

Gallium-based metallic drugs and agents have been widely applied for the diagnosis and treatment of diseases such as non-Hodgkin's lymphoma (NHL), but there are few reports on the potential Ga(III)-binding proteins and the related cytotoxic mechanisms for Ga(III). Herein, by using human urinary bladder cancer T24 cells as a model, we identify and report that tubulin is a Ga(III)-binding protein target in T24 cells. Our analyses, including the employment of a series of methods based on immobilized metal affinity chromatography (IMAC), cellular thermal shift assay (CETSA), and immunofluorescence experiments, collectively explained this finding. Our results suggest that the binding of Ga(III) to tubulin led to significant changes in the morphology and distribution of microtubules in cells. The blocked microtubule formation or microtubule depolymerization as a result of the binding of Ga(III) to tubulin may be an important molecular mechanism by which Ga(III) exerts its cytotoxic effects in T24 cells to inhibit tumor cell growth.

Saikosaponin A targets HDAC6 to inhibit Mycobacterium tuberculosis-induced macrophage Pyroptosis via autophagy-mediated NLRP3 inflammasome inactivation

BACKGROUND

Mycobacterium tuberculosis (Mtb) is among the oldest and most resilient human pathogens, remaining a major global public health threat. Its characteristic pathological features include granuloma formation and a systemic inflammatory response, primarily resulting from dysregulated host immune reactions. Therefore, host-directed therapy (HDT) is considered an important complement to conventional anti-TB treatment.

PURPOSE

This study sought to examine the inhibitory effects of Saikosaponin A (SSA), an active compound extracted from Bupleurum, on Mtb-induced macrophage pyroptosis, as well as the underlying molecular mechanisms.

METHODS

The effects of SSA on key molecules involved in pyroptosis and autophagy were examined in an in vitro model of Mtb-infected macrophages using Western blotting, ELISA, co-immunoprecipitation, and immunofluorescence assays. The function of histone deacetylase 6 (HDAC6) in modulating autophagy and pyroptosis in Mtb-infected macrophages was elucidated using gene silencing techniques. The SSA-HDAC6 interaction was validated using drug target identification methods such as molecular docking and site-directed mutagenesis. Furthermore, we established an in vivo model of lipopolysaccharide-induced pulmonary inflammation via intraperitoneal injection to assess whether SSA exerts a protective effect by inhibiting pyroptosis.

RESULTS

In vitro experiments demonstrated that SSA enhanced autophagy to inactivate the NLRP3 inflammasome, thereby inhibiting Mtb-induced pyroptosis. Mechanistically, SSA interacted with HDAC6 and effectively suppressed its enzymatic activity. This interaction enabled SSA to target HDAC6, thereby modulating autophagy via the AMPK/mTOR/ULK1 axis, ultimately attenuating Mtb-induced pyroptosis in macrophages. Furthermore, in vivo experiments revealed that SSA regulated the acetylation of α-tubulin (Lys40), alleviating inflammatory lung injury in mice.

CONCLUSION

SSA targets HDAC6 and exerts an immunomodulatory effect, highlighting its potential as a promising novel host-directed anti-tuberculosis agent.

Rethinking tubulin acetylation: From regulation to cellular adaptation

Ever since its discovery, acetylation of α-tubulin on lysine 40 (K40) has been associated with the presence of long-lived, stable microtubules. Indeed, later studies revealed that acetylation protects microtubules from mechanical breakage, yet the functional consequences of this modification at the cellular level are only beginning to emerge. Here, we outline novel insights into the mechanisms controlling tubulin acetylation, and its impact on microtubule properties and cellular functions. Finally, we highlight recent advances suggesting that tubulin acetylation can also occur as a dynamic modification in response to a variety of cellular stresses. These observations shed new light on the cell biological functions of tubulin acetylation and give rise to the notion that this modification could be a universal mechanism that allows cells to adapt to changes in their environment or intracellular state.

Importance of tubulin detyrosination in platelet biogenesis

BACKGROUND

The functional diversity of microtubules is regulated through the expression of distinct α- and β-tubulin isotypes together with several posttranslational modifications, a concept known as tubulin code. Tubulin detyrosination is a reversible posttranslational modification that consists of the removal of the genetically encoded C-terminal tyrosine residue of most α-tubulins. While this modification has been observed in the megakaryocyte lineage, its importance remains poorly understood in platelet biogenesis.

OBJECTIVES

To assess the role of α-tubulin detyrosination in platelet biogenesis.

METHODS

The responsible enzymes and the relative abundance of detyrosinated α-tubulins were monitored by quantitative reverse transcription-polymerase chain reaction and Western blotting, respectively, in human cultured megakaryocytes and platelets differentiated from CD34+ hematopoietic stem and progenitor cells. The function of α-tubulin detyrosination was assessed in human cultured megakaryocytes treated with the VASH-SVBP inhibitor EpoY, and in mice constitutively inactivated for Svbp (which encodes the cofactor of the VASH detyrosinases).

RESULTS

Transcriptional analysis identified VASH1-SVBP and MATCAP as the predominant detyrosinases in the megakaryocyte lineage. During megakaryocyte maturation, their transcript levels progressively increased and correlated with the accumulation of detyrosinated α-tubulins. Remarkably, inhibition of VASH1-SVBP by EpoY abolished tubulin detyrosination, establishing VASH1-SVBP as the main functional detyrosinase in megakaryocytes. More importantly, EpoY enhanced proplatelet formation and platelet production in vitro. These in vitro data were confirmed in vivo in SVBP-deficient mice, which exhibited an increase in platelet counts.

CONCLUSION

These findings reveal, for the first time, a role for tubulin detyrosination in proplatelet formation, thereby expanding our understanding of the megakaryocyte tubulin code beyond tubulin isotypes.

PCP protein Prickle 1 regulates Sertoli cell and testis function via cytoskeletal organization through the recruitment of multiple regulatory proteins

Prickle 1, an ortholog found in Drosophila, was localized at the Sertoli cell-spermatid interface consistent with its role of supporting the Vangl2 planar cell polarity (PCP), which is an integral membrane protein that creates the PCP protein complex of Vangl2 (Van Gogh-like 2)/Prickle1. Together with the asymmetrically localized transmembrane protein Frizzled (Fzd) and its unique adaptor proteins Disheveled (Dvl) and Inversin (Inv), Vangl2/Prickle1 and Fzd/Dvl/Inv are the two heterodimeric interacting PCP proteins between Sertoli cells and condensed spermatids to confer spermatid PCP across the plane of the seminiferous epithelium. Our initial intention was to examine if the distribution and expression of Prickle1 using a primary Sertoli cell in vitro model and Sprague-Dawley rats in vivo would mimic much of the earlier reported findings of Vangl2. Unexpectedly, these findings indicated that Prickle1 supported the PCP protein Vangl2; however, Prickle1 is also a multifunctional protein. First, Prickle1 knockdown (KD) by RNAi impeded Sertoli cell TJ function by perturbing the distribution of the BTB-associated proteins at the cell-cell interface, through disruption of the microtubule (MT) and actin cytoskeletal organization including their respective polymerization (and/or bundling) capability. Second, these findings were reproduced using an in vivo model of RNAi by KD of Prickle 1 in the testis. Third, using coimmunoprecipitation (Co-IP), Prickle 1 was found to interact with a host of adaptor proteins crucial to support not only PCP, such as Dvl, but also regulatory cytoskeletal proteins of MT and actin networks, including RhoA, Arp3, Cdc42, ZO-1, and β-catenin by immunoprecipitation-mass spectrometry (IP-MS) using the String Protein Interaction Tool.NEW & NOTEWORTHY This article was written based on results from a series of experiments to understand the function of planar cell polarity (PCP) protein Prickle 1 in the testis to support spermatogenesis. It was unexpectedly shown that Prickle1 was found to recruit several important regulatory proteins at the site where the Sertoli cell and condensed spermatids interact to modulate cytoskeletal functions of both actin and microtubule. These findings are important to both cell and molecular biologists.

Isoform-specific phosphorylation of axonemal dynein heavy chains

Axonemal dyneins power ciliary motility and phosphorylation of key intermediate and light chain components affects the regulation and properties of these motors in very distantly related organisms. It is also known that many axonemal dynein heavy chains are subject to this posttranslational modification although this has been little studied. Here we examine axonemal dynein heavy chains from a broad range of ciliated eukaryotes and identify phosphorylated sites embedded within various kinase recognition motifs such as those for protein kinase A, protein kinase C, and casein kinase II. Mapping these sites onto discrete heavy chain types reveals class-specific locations apparently mediated by different kinases. For example, we find that all Chlamydomonas α heavy chain phosphorylation sites are in an extended loop derived from AAA5 that arches over the coiled-coil buttress which in turn interacts with the microtubule-binding stalk. In contrast, most sites in the monomeric inner arm dyneins occur very close to the N-terminus and may be involved in assembly processes. In Chlamydomonas, the two cilia (termed cis and trans) exhibit different intrinsic beat frequencies and we identify cilium-specific phosphorylation patterns on both the α heavy chain and outer arm docking complex consistent with differential regulation of these motors in the two organelles.

Function of manchette and intra-manchette transport in spermatogenesis and male fertility

The manchette is a transient skirt-like structure consisting of microtubules (MTs) and filamentous actin (F-actin) surrounding the elongating sperm head during spermiogenesis. It is pivotal in sperm head shaping controlled by the acrosome-acroplaxome-manchette complex, acrosome formation, and flagellar assembly by microtubular-based protein delivery. Defects in the manchette frequently lead to teratozoospermia concomitant with oligozoospermia and asthenozoospermia, but the pathogenic mechanism underlying manchette function and its role in male infertility remain poorly understood. In this review, we systematically described the assembly and disassembly of the manchette, intra-manchette transport (IMT) and its regulatory model, the function and mechanism of manchette and IMT in regulating sperm head shaping and flagellar assembly during spermatogenesis; summarized the research progress of manchette-related genes related to male infertility; and listed the manchette-related proteins in knockout mouse models and clinical cases, which provide the theoretical basis for an in-depth understanding of the molecular mechanism of manchette involved in spermatogenesis and male fertility for understanding the potentially developing treatments for infertility and reproductive disorders.

Cytoplasmic connexin43-microtubule interactions promote glioblastoma stem-like cell maintenance and tumorigenicity

Glioblastoma (GBM) is the most common primary tumor of the central nervous system. One major challenge in GBM treatment is the resistance to chemotherapy and radiotherapy observed in subpopulations of cancer cells, including GBM stem-like cells (GSCs). These cells have the capacity to self-renew and differentiate and as such, GSCs participate in tumor recurrence following treatment. The gap junction protein connexin43 (Cx43) has complex roles in oncogenesis and we have previously demonstrated an association between Cx43 and GBM chemotherapy resistance. Here, we report, for the first time, increased direct interaction between non-junctional Cx43 and microtubules in the cytoplasm of GSCs. We hypothesize that non-junctional Cx43/microtubule complexing is critical for GSC maintenance and survival and sought to specifically disrupt this interaction while maintaining other Cx43 functions, such as gap junction formation. Using a Cx43 mimetic peptide of the carboxyl terminal tubulin-binding domain of Cx43 (JM2), we successfully disrupted Cx43 interaction with microtubules in GSCs. Importantly, administration of JM2 significantly decreased GSC survival in vitro, and limited GSC-derived and GBM patient-derived xenograft tumor growth in vivo. Together, these results identify JM2 as a novel peptide drug to ablate GSCs in GBM treatment.

Perfluorooctane sulfonate induced ferritinophagy via detyrosinated alpha tubulin-TRIM21-HERC2-regulated NCOA4 degradation in hepatocytes

The persistent organic pollutant perfluorooctane sulfonate (PFOS) is demonstrated to induce hepatotoxicity through disrupting iron homeostasis and subsequent ferroptosis in hepatocytes. However, it is still elusive in the mechanisms underneath the dysfunctional iron metabolism caused by PFOS. In this study, we observed that PFOS activated the nuclear receptor coactivator 4 (NCOA4)-mediated ferritinophagy in mice liver and human hepatocytes. PFOS reduced the ubiquitination of NCOA4, subsequently causing an increase in the expression of NCOA4. PFOS induced the ubiquitination of HECT and RLD domain-containing E3 ubiquitin protein ligase 2 (HERC2), an upstream negative regulator of NCOA4, leading to the degradation of HERC2. PFOS upregulated the level of detyrosinated α-tubulin (detyr-α-tubulin) in hepatocytes. Under PFOS exposure, detyr-α-tubulin interacted with tripartite motif containing 21 (TRIM21), another E3 ubiquitin ligase responsible for HERC2 degradation. Despite the reduction in the protein level of HERC2, the increases in detyr-α-tubulin and the interaction between detyr-α-tubulin and TRIM21 caused by PFOS facilitated the interaction between TRIM21 and HERC2. Furthermore, inhibiting α-tubulin detyrosination by parthenolide reversed the ferritinophagy and the following ferroptosis caused by PFOS. Collectively, this study points out the existence of ferritinophagy and enriches the understanding of the alteration in iron metabolism under PFOS exposure, providing novel mechanistic insights into the hepatic toxicity of PFOS.

Transcriptomic profiling revealed the regulatory pathways and key genes associated with cold tolerance in two eel gobies

Closely related species of the eel goby family (Gobiidae) have evolved divergent resistance to low temperatures, but the molecular mechanisms remain poorly understood. This study used a comparative transcriptomic approach to identify key pathways and genes associated with cold tolerance in two eel goby species. Expression profiles of the cold-tolerant O. lacepedii and the cold-sensitive O. rebecca in control (23 °C) and cold stress groups (15 °C and 11 °C) were analyzed. Differentially expressed genes closely linked to interspecific cold tolerance divergence were identified through transcriptome profiling and Venn diagram analysis. GO and KEGG enrichment analyses revealed that processes related to cellular homeostasis, the PPAR signaling pathway, cellular respiration, and oxidative phosphorylation were activated during the cold tolerance response of eel gobies. WGCNA analysis indicated that the hub genes related to thermogenesis and microtubular stability, specifically PPARGC1A and α-tubulin, may contribute to the high cold tolerance in O. lacepedii. These findings provide key clues for dissection of the molecular mechanisms behind the formation of cold tolerance in eel gobies.

Mechanical stimulation prevents impairment of axon growth and overcompensates microtubule destabilization in cellular models of Alzheimer's disease and related Tau pathologies

Alzheimer's disease (AD) and related tauopathies such as frontotemporal dementia (FTD) or traumatic brain injury (TBI) are neurodegenerative disorders characterized by progressive loss of memory and cognitive function. The main histopathological features of AD are amyloid-β plaques and Tau neurofibrillary tangles, suggested to interfere with neuronal function and to cause microtubule (MT) destabilization. We recently demonstrated that low mechanical forces promote MT stabilization, which in turn promotes axon growth and neuronal maturation. As neurites may become dystrophic due to MT destabilization in tauopathies, we hypothesized that force-induced MT stabilization is neuroprotective in cell models subjected to tauopathy-like stress. We set up two different pathological cellular models subjecting them to AD-related Tau pathology stressors. We found that exposure of mouse primary neurons to Tau oligomers and neurons derived from human induced pluripotent stem cell (hiPSC) to amyloid-β oligomers resulted in neurotoxic effects such as axonal shortening, reduction in dendrite number, and MT destabilization. Mechanical stimulation (i) prevented delays in axonal extensions and dendrite sprouting, restoring axon outgrowth to physiological levels, and (ii) compensated for axonal MT destabilization by increasing MT stability to levels higher than in control conditions. In summary, we here demonstrate that low mechanical force can be used as a neuroprotective extrinsic factor to prevent MT destabilization and axon degeneration caused by AD-like or tauopathy-like stressors.

Peptide-mediated display of Tau-derived peptide for construction of microtubule superstructures

Microtubules are major cytoskeletons involved in various cellular functions, such as regulating cell shape and division and cargo transport via motor proteins. In addition to widely studied singlet microtubules, complex microtubule superstructures, including doublets and bundles, provide unique mechanical and functional properties in vivo. However, a method to construct such superstructures in vitro remains unresolved. This study presents a peptide-based approach for constructing microtubule superstructures by displaying Tau-derived peptides (TP) on the outer surface of microtubules using KA7 peptides as binding units. The KA7-connected TP (KA7-TP) bound to the C-terminal tail on the outer surface of microtubules and induced doublets and bundles by recruiting tubulin. Notably, the outer layers of the doublet microtubules generated by KA7-TP dissociated, highlighting the utility of this approach for studying the formation/dissociation mechanisms of microtubule superstructures. The simple peptide-based approach facilitates our understanding of microtubule superstructures and offers new opportunities for applying microtubule superstructures to nanotechnology.

Lactylation as a metabolic epigenetic modification: Mechanistic insights and regulatory pathways from cells to organs and diseases

In recent years, lactylation, a novel post-translational modification, has demonstrated a unique role in bridging cellular metabolism and epigenetic regulation. This modification exerts a dual-edged effect in both cancer and non-cancer diseases by dynamically integrating the supply of metabolic substrates and the activity of modifying enzymes: on one hand, it promotes tissue homeostasis and repair through the activation of repair genes; on the other, it exacerbates pathological progression by driving malignant phenotypes. In the field of oncology, lactylation regulates key processes such as metabolic reprogramming, immune evasion, and therapeutic resistance, thereby shaping the heterogeneity of the tumor microenvironment. In non-cancerous diseases, including neurodegeneration and cardiovascular disorders, its aberrant activation can lead to mitochondrial dysfunction, fibrosis, and chronic inflammation. Existing studies have revealed a dynamic regulatory network formed by the cooperation of modifying and demodifying enzymes, and have identified mechanisms such as subcellular localization and RNA metabolism intervention that influence disease progression. Nevertheless, several challenges remain in the field. This article comprehensively summarizes the disease-specific regulatory mechanisms of lactylation, with the aim of providing a theoretical foundation for its targeted therapeutic application.

Glutamylation of centrosomes ensures their function by recruiting microtubule nucleation factors

Centrosomes are tubulin-based organelles that undergo glutamylation, a post-translational modification that conjugates glutamic acid residues to tubulins. Although centrosomal glutamylation has been known for several decades, how this modification regulates centrosome structure and function remains unclear. To address this long-standing issue, we developed a method to spatiotemporally reduce centrosomal glutamylation by recruiting an engineered deglutamylase to centrosomes. We found that centrosome structure remains largely unaffected by centrosomal hypoglutamylation. Intriguingly, glutamylation physically recruits, via electrostatic forces, the NEDD1/CEP192/γ-tubulin complex to centrosomes, ensuring microtubule nucleation and proper trafficking of centriolar satellites. The consequent defect in centriolar satellite trafficking leads to reduced levels of the ciliogenesis factor Talpid3, suppressing ciliogenesis. Centrosome glutamylation also promotes proper mitotic spindle formation and mitosis. In summary, our study provides a new approach to spatiotemporally manipulate glutamylation at centrosomes, and offers novel insights into how centrosomes are organized and regulated by glutamylation.

Mechanics of Single Cytoskeletal Filaments

The cytoskeleton comprises networks of different biopolymers, which serve various cellular functions. To accomplish these tasks, their mechanical properties are of particular importance. Understanding them requires detailed knowledge of the mechanical properties of the individual filaments that make up these networks, in particular, microtubules, actin filaments, and intermediate filaments. Far from being homogeneous beams, cytoskeletal filaments have complex mechanical properties, which are directly related to the specific structural arrangement of their subunits. They are also versatile, as the filaments' mechanics and biochemistry are tightly coupled, and their properties can vary with the cellular context. In this review, we summarize decades of research on cytoskeletal filament mechanics, highlighting their most salient features and discussing recent insights from this active field of research.

Sec61β, a subunit of the Sec61 complex at the endoplasmic reticulum, coordinates with Ocnus in regulating Drosophila spermatogenesis

sec61β encodes a subunit of the Sec61 translocon which is a highly conserved heterotrimer responsible for translocating the nascent polypeptides into the lumen of the endoplasmic reticulum (ER) or onto the ER membrane. In this study, we show that knockdown of sec61β in the early germline leads to male sterility in Drosophila melanogaster. These males exhibit testes that are dramatically reduced in size and devoid of germ cells. However, the somatic cells with hub markers extend abnormally beyond the stem cell niche region. Stat92E-positive cells are also expanded into the posterior region of the small testes and primarily in the nuclei. Through tracking the developmental processes of germ cells, we find that the loss of germ cells occurs during the 3rd instar larval stage. Additionally, studies in Drosophila S2 cells reveal that Sec61β can directly interact with Ocnus (Ocn), likely at the nuclear membrane. Genetically, we show that overexpression of ocn partially restores fertility in sec61β knockdown males, while overexpression of sec61β fails to compensate for the defects in male fertility induced by ocn knockdown. These findings suggest that Sec61β might play a critical role in testis development and spermatogenesis, potentially coordinating with Ocn and involving in the JAK/STAT pathway.

Liquid-Liquid Phase Separation-Mediated Cellular-Scale Compartmentalization of Hydrogel Covalent Cross-Linking Promotes Microtubule-Based Mechanosensing

Controlled liquid-liquid phase separation (LLPS) plays an important role in the formation of a heterogeneously structured extracellular matrix (ECM) consisting of densely cross-linked stiff structures compartmentalized in a loosely cross-linked matrix. Moreover, the mechanical cues presented by the cellular-scale structural heterogeneity of the ECM facilitate the mechanotransduction of cells and subsequent cellular development. Therefore, developing ECM-mimetic hydrogels with compartmentalized structural heterogeneity as inductive cell carriers is highly desirable but challenging. Inspired by the ECM formation process, we capitalized on the temperature-assisted LLPS of a custom-designed temperature-responsive macromer (TRM) to concentrate and compartmentalize the TRM in the dense phase of the phase-separated precursor solution while keeping the gelatin comacromer complex in the dilute phase. The subsequent cross-linking produces the cellular (micron)-scale microdomains with dense covalent cross-linking interspersed in the loosely cross-linked cell-adaptable interdomain hydrogel matrix. The obtained ECM-mimetic heterogeneous hydrogel, which is solely cross-linked by covalent bonds, promotes extensive spreading, microtubule-based mechanotransduction, and autophagic flux of encapsulated human mesenchymal stem cells (hMSCs), thereby enhancing osteogenesis and bone regeneration. Our findings not only provide valuable guidance for the fabrication of ECM-mimetic biomaterials via LLPS-mediated assembly but also shed light on the mechanobiological mechanism underlying the regulation of cellular development by mechanical cues of the ECM.

Unveiling β-Tubulin Isotype-1 Polymorphisms in Haemonchus contortus from Pakistani Livestock: New Insights into Benzimidazole Resistance and Protein Structure Analysis

BACKGROUND

Haemonchus contortus, a gastrointestinal hematophagous parasitic nematode, causes substantial economic losses to the livestock sector across the globe. The widespread use of benzimidazoles in livestock has contributed greatly to the evolution of resistance in H. contortus. To effectively tackle this expanding threat, regular and diligent monitoring is required to identify and manage resistance, ensuring that treatment techniques continue to be effective.

OBJECTIVES

This study aimed to investigate the genetic and structural variations in β-tubulin isotype-1 of Haemonchus contortus isolated from goats and cattle in Pakistan, with a focus on understanding the mechanisms underlying resistance to benzimidazole.

METHODS

A total of 150 goats and 100 cattle from four abattoirs in Rawalpindi were tested for Haemonchus contortus. Faecal samples were cultured for L3 larvae, DNA was isolated, and whole genome sequencing was performed. β-tubulin isotype 1 gene sequence was extracted. Phylogenetic tree with reference genome from GenBank, and protein models were generated via ExPaSy and I-TASSER and validated with SAVESv.6.0.

RESULTS

Six genotypes of Haemonchus contortus isotype1 β-tubulin gene, each with a length of 385 base pairs were identified. The E198A SNP was the most prevalent mutation among the larvae of Haemonchus contortus collected from cattle (62.5%) and goats (50%), followed by the F200Y which was detected in 6 (37.5%) larvae collected from cattle and 9 (37.5%) larvae from goats. SNP F167Y was not identified in any of the samples. The phylogenetic analysis showed that the isolates were closely related to H. contortus from China (KX258930) and H. contortus × H. placei hybrids from Pakistan. Six genotypes of β-tubulin isotype 1 gene were translated into three haplotypes based on protein sequences: wild type/susceptible, E198A-resistant/mutant, and F200Y-resistant/mutant. Structural analysis revealed high model quality and confidence, with the E198A and F200Y resistant/mutants exhibiting different characteristics, with refined quality factors exceeding 91%.

CONCLUSION

The study demonstrated alterations in tubulin structure and function are crucial for understanding anthelmintic resistance patterns. These findings help for improving therapeutic approaches, comprehending resistance mechanisms, and promoting sustainable parasite control.

Regulation of microtubule growth rates and their impact on chromosomal instability

Microtubules are polymers of α/β tubulin dimers that build the mitotic spindle, which segregates duplicated chromosomes during cell division. Microtubule function is governed by dynamic instability, whereby cycles of growth and shrinkage contribute to the forces necessary for chromosome movement. Regulation of microtubule growth velocity requires cell cycle-dependent changes in expression, localization and activity of microtubule-associated proteins (MAPs) as well as tubulin post-translational modifications that modulate microtubule dynamics. It has become clear that optimal microtubule growth velocities are required for proper chromosome segregation and ploidy maintenance. Suboptimal microtubule growth rates can result from altered activity of MAPs and could lead to aneuploidy, possibly by disrupting the establishment of microtubule bundles at kinetochores and altering the mechanical forces required for sister chromatid segregation. Future work using high-resolution, low-phototoxicity microscopy and novel fluorescent markers will be invaluable in obtaining deeper mechanistic insights into how microtubule processes contribute to chromosome segregation.

Alpha-tubulin tails regulate axoneme differentiation

The tubulin tail is a key element for microtubule (MT) functionality, but the functional redundancy of tubulin genes complicates the genetic determination of their physiological functions. Here, we removed the C-terminal tail of five alpha- and four beta-tubulin genes in the C. elegans genome. Sensory cilia typically exhibit an axoneme that longitudinally differentiates into a middle segment with doublet MTs and a distal segment with singlet MTs. However, the excision of the alpha-tubulin tail, but not the beta-tubulin tail, resulted in the ectopic formation of doublet MTs in the distal segments. Molecular dynamics simulations suggest that the alpha-tubulin tail could prevent the B-tubule from docking on the surface of A-tubule. Using recombinant tubulins, we demonstrated that removing the alpha-tubulin tail efficiently promoted doublet MTs formation in vitro. These results reveal the vital and unique contributions of tubulin tails to the structural integrity and accuracy of axoneme MT organization.

The alpha tubulin acetyltransferase atat-2 genetically interacts with klp-4 in C. elegans

Microtubules dynamics are in part regulated by post-translational modification, including acetylation. Little is known about the relationship between microtubule acetylation status and how this affects kinesin function, especially in vivo . Using a series of aldicarb sensitivity assays in C. elegans where we combined pharmacological manipulation of microtubule dynamics with genetic approaches, we demonstrate a specific genetic interaction between the alpha tubulin acetyltransferase atat-2 and the kinesin motor klp-4 . Our work highlights interactions between kinesin activity and the tubulin code in vivo and lays the foundation of future work on these two parallel, yet related processes in cells.

Redox signaling modulates axonal microtubule organization and induces a specific phosphorylation signature of microtubule-regulating proteins

Many life processes are regulated by physiological redox signaling, but excessive oxidative stress can damage biomolecules and contribute to disease. Neuronal microtubules are critically involved in axon homeostasis, regulation of axonal transport, and neurodegenerative processes. However, whether and how physiological redox signaling affects axonal microtubules is largely unknown. Using live cell imaging and super-resolution microscopy, we show that subtoxic concentrations of the central redox metabolite hydrogen peroxide increase axonal microtubule dynamics, alter the structure of the axonal microtubule array, and affect the efficiency of axonal transport. We report that the mitochondria-targeting antioxidant SkQ1 and the microtubule stabilizer EpoD abolish the increase in microtubule dynamics. We found that hydrogen peroxide specifically modulates the phosphorylation state of microtubule-regulating proteins, which differs from arsenite as an alternative stress inducer, and induces a largely non-overlapping phosphorylation pattern of MAP1B as a main target. Cell-wide phosphoproteome analysis revealed signaling pathways that are inversely activated by hydrogen peroxide and arsenite. In particular, hydrogen peroxide treatment was associated with kinases that suppress apoptosis and regulate brain metabolism (PRKDC, CK2, PDKs), suggesting that these pathways play a central role in physiological redox signaling and modulation of axonal microtubule organization. The results suggest that the redox metabolite and second messenger hydrogen peroxide induces rapid and local reorganization of the microtubule array in response to mitochondrial activity or as a messenger from neighboring cells by activating specific signaling cascades.

Molecular and functional characterization of a β-tubulin gene in Plutella xylostella

The β-tubulin gene is essential for reproductive development, especially for male fertility, in different insects including Bombyx mori and Drosophila melanogaster. Targeting reproductive genes such as β-tubulin offers a promising approach to pest control that is more sustainable than chemical pesticides. However, there is limited research on the functional role of β-tubulin in Plutella xylostella, a highly damaging pest of vegetable crops. In the present study, we first identified and cloned the β-tubulin gene in P. xylostella (Pxβtubulin-1). Pxβtubulin-1 protein contains two conserved domains of Tubulin and Tubulin-C, and β-tubulin were conserved in the Lepidoptera. Spatiotemporal expression analysis revealed that Pxβtubulin-1 was highly expressed in male pupae, adult males, and testes, suggesting its testis-specific function. Using CRISPR/Cas9 technology, we generated two homozygous Pxβtubulin-1 mutant strains of P. xylostella. Mutant strains exhibited significantly lower egg production and hatching rates compared with the wild type. Dissection and measurement of reproductive organs revealed that the testes and bursa copulatrix in mutant strains were significantly reduced in size compared with the wild type. In conclusion, Pxβtubulin-1 is vital for male fertility as it influences the development of reproductive organs and can be a potential target for the control of P. xylostella.

Microtubule acetylation is a biomarker of cytoplasmic health during cellular senescence

Cellular senescence is marked by cytoskeletal dysfunction, yet the role of microtubule post-translational modifications (PTMs) remains unclear. We demonstrate that microtubule acetylation increases during drug-induced senescence in human cells and during natural aging in Drosophila . Elevating acetylation via HDAC6 inhibition or α TAT1 overexpression in BEAS-2B cells disrupts anterograde Rab6A vesicle transport, but spares retrograde transport of Rab5 endosomes. Hyperacetylation results in slowed microtubule polymerization and decreased cytoplasmic fluidity, impeding diffusion of micron-sized condensates. These effects are distinct from enhanced detyrosination, and correlate with altered viscoelasticity and resistance to osmotic stress. Modulating cytoplasmic viscosity reciprocally perturbs microtubule dynamics, revealing bidirectional mechanical regulation. Senescent cells phenocopy hyperacetylated cells, exhibiting analogous effects on transport and microtubule polymerization. Our findings establish acetylation as a biomarker for cytoplasmic health and a potential driver of age-related cytoplasmic densification and organelle transport decline, linking microtubule PTMs to biomechanical feedback loops that exacerbate senescence. This work highlights the role of acetylation in bridging cytoskeletal changes to broader aging hallmarks.

Tubulin targeting agents and their implications in non-cancer disease management

Microtubules act as molecular 'tracks' for the intracellular transport of accessory proteins, enabling them to assemble into various larger structures, such as spindle fibres formed during the cell cycle. Microtubules provide an organisational framework for the healthy functioning of various cellular processes that work through the process of dynamic instability, driven by the hydrolysis of GTP. In this role, tubulin proteins undergo various modifications, and in doing so modulate various healthy or pathogenic physiological processes within cells. In this review, we provide a detailed update of small molecule chemical agents that interact with tubulin, along with their implications, specifically in non-cancer disease management.

Phyloproteomics reveals conserved patterns of axonemal dynein methylation across the motile ciliated eukaryotes

Axonemal dynein assembly occurs in the cytoplasm and numerous cytosolic factors are specifically required for this process. Recently, one factor (DNAAF3/PF22) was identified as a methyltransferase. Examination of Chlamydomonas dyneins found they are methylated at substoichiometric levels on multiple sites, including Lys and Arg residues in several of the nucleotide-binding domains and on the microtubule-binding region. Given the highly conserved nature of axonemal dyneins, one key question is whether methylation happens only in dyneins from the chlorophyte algae, or whether these modifications occur more broadly throughout the motile ciliated eukaryotes. Here we take a phyloproteomic approach and examine dynein methylation in a wide range of eukaryotic organisms bearing motile cilia. We find unambiguous evidence for methylation of axonemal dyneins in alveolates, chlorophytes, trypanosomes, and a broad range of metazoans. Intriguingly, we were unable to identify a single instance of methylation on Drosophila melanogaster sperm dyneins even though dipterans express a Dnaaf3 orthologue, or in spermatozoids of the fern Ceratopteris, which assembles inner arms but lacks both outer arm dyneins and DNAAF3. Thus, methylation of axonemal dyneins has been broadly conserved in most eukaryotic groups and has the potential to variably modify the function of these motors.

KIF2C promotes paclitaxel resistance by depolymerizing polyglutamylated microtubules

The long-term effectiveness of paclitaxel is limited by chemoresistance. In this study, we elucidate the molecular mechanism by which kinesin family member 2C (KIF2C), a well-known microtubule depolymerase, contributes to the development of chemoresistance in triple-negative breast cancer (TNBC). We observed elevated levels of KIF2C, tubulin tyrosination, and polyglutamylation in human and mouse breast cancer cells resistant to paclitaxel. Additionally, these chemoresistant cells possessed cross-resistance to diverse microtubule-targeting agents (MTAs). We demonstrated that KIF2C preferentially depolymerizes polyglutamylated tubulin, even in the presence of paclitaxel. To counter this, we developed 7S9, a chemical inhibitor of KIF2C, that prohibits the dissociation of KIF2C from microtubules. The combination of 7S9 and paclitaxel significantly reduced tumorigenesis in chemoresistant TNBC model in mice. Moreover, 7S9 diminished cancer cell chemoresistance to several clinically available MTAs. Our findings elucidate the molecular mechanism of KIF2C-mediated chemoresistance and highlight KIF2C as a promising target for combating cross-resistance in TNBC.

Kinesin family member 14 expression and its clinical implications in colorectal cancer

BACKGROUND

Colorectal cancer (CRC) is the third most common cancer globally, causing over 900000 deaths annually. Risk factors include aging, diet, obesity, sedentary lifestyle, tobacco use, genetic predisposition, and inflammatory bowel disease. Despite current treatments, survival rates for advanced CRC remain low, highlighting the need for better therapeutic strategies.

AIM

To evaluate both the clinical significance and the pathological implications of the Kinesin family member 14 (KIF14) expression within CRC specimens. Additionally, this study aims to investigate the interaction between nitidine chloride (NC) and KIF14, considering their potential as therapeutic targets.

METHODS

The expression of the KIF14 protein in CRC was analyzed using immunohistochemical staining. The integration of multicenter high-throughput data facilitated the calculation of the standardized mean difference (SMD) for KIF14 mRNA levels. The assessment of clinical and pathological impact was enhanced by analyzing combined receiver operating characteristic curves, along with measures of sensitivity, specificity, and likelihood ratios. Additionally, clustered regularly interspaced short palindromic repeats knockout screening for cell growth and single-cell sequencing were employed to validate the significance of KIF14 expression in CRC. Survival analysis established the prognostic value of KIF14 in CRC. The molecular mechanism of NC against CRC was elucidated through whole-genome sequencing and enrichment analysis, and molecular docking was utilized to explore the targeting affinity between NC and KIF14.

RESULTS

KIF14 was highly expressed in 208 CRC patients. Data from 17 platforms involving 2436 CRC samples and 1320 noncancerous colorectal tissue controls indicated that KIF14 expression was significantly higher in CRC samples, with an SMD of 1.92 (95%CI: 1.49-2.35). The area under the curve was 0.94 (95%CI: 0.92-0.96), with a sensitivity of 0.85 (95%CI: 0.78-0.90) and a specificity of 0.90 (95%CI: 0.85-0.93). The positive and negative likelihood ratios were 8.38 (95%CI: 5.39-13.02) and 0.17 (95%CI: 0.11-0.26), respectively. At the single-cell level, significant overexpression of KIF14 was observed in CRC cells (P < 0.001), with 35 CRC cell lines dependent on KIF14 for growth. The K-M plots demonstrated that KIF14 possesses prognostic value in CRC patients within the GSE71187 and GSE103679 datasets (P < 0.05). Binding energy calculations indicated that KIF14 is a potential target for NC (binding energy: 10.3 kcal/mol).

CONCLUSION

KIF14 promotes the growth of CRC cells and acts as an oncogenic factor, potentially serving as a therapeutic target for NC in the treatment of CRC.

Discovery of novel thienopyridine indole derivatives as inhibitors of tubulin polymerization targeting the colchicine-binding site with potent anticancer activities

Based on the molecular hybridization strategy, novel thienopyridine indole derivatives were designed and synthesized as tubulin polymerization inhibitors, and the in vitro antiproliferative potency on MGC-803, KYSE450 and HCT-116 cells was evaluated. Among them, compound 20b showed a broad-spectrum antiproliferative activity against 11 cancer cell lines, with IC50 values below 4 nmol/L. Notably, it demonstrated exceptional efficacy against MGC-803 (IC50 = 1.61 nmol/L) and HGC-27 (IC50 = 1.82 nmol/L) cells. Further mechanism explorations suggested that compound 20b could inhibit tubulin polymerization (IC50 = 2.505 μmol/L) by acting on the colchicine binding site, thereby disrupting intracellular microtubule networks and interfering with cell mitosis. In addition, compound 20b effectively inhibited the colony formation and cell migration activities, and induced G2/M phase cycle arrest and apoptosis in MGC-803 and HGC-27 cells. Besides, compound 20b also displayed potent anti-angiogenesis effects on HUVECs. Importantly, compound 20b demonstrated oral efficacy in inhibiting tumor growth with a TGI of 45.8 % (5 mg/kg/qod) in the mouse xenograft model bearing MGC-803 cells, surpassing that of CA-4 (TGI of 27.1 % at 20 mg/kg/qod), as well as also exhibited a good safety profile. Therefore, these results suggested that the thienopyridine indole derivative 20b represents a novel tubulin inhibitor with potent anticancer efficacy that inhibits gastric cancers.

Translatome analysis reveals cellular network in DLK-dependent hippocampal glutamatergic neuron degeneration

The conserved MAP3K12/Dual Leucine Zipper Kinase (DLK) plays versatile roles in neuronal development, axon injury and stress responses, and neurodegeneration, depending on cell-type and cellular contexts. Emerging evidence implicates abnormal DLK signaling in several neurodegenerative diseases. However, our understanding of the DLK-dependent gene network in the central nervous system remains limited. Here, we investigated the roles of DLK in hippocampal glutamatergic neurons using conditional knockout and induced overexpression mice. We found that dorsal CA1 and dentate gyrus neurons are vulnerable to elevated expression of DLK, while CA3 neurons appear less vulnerable. We identified the DLK-dependent translatome that includes conserved molecular signatures and displays cell-type specificity. Increasing DLK signaling is associated with disruptions to microtubules, potentially involving STMN4. Additionally, primary cultured hippocampal neurons expressing different levels of DLK show altered neurite outgrowth, axon specification, and synapse formation. The identification of translational targets of DLK in hippocampal glutamatergic neurons has relevance to our understanding of selective neuron vulnerability under stress and pathological conditions.

Physical effects of crowdant size and concentration on collective microtubule polymerization

The polymerization of cytoskeletal filaments is regulated by both biochemical pathways, as well as physical factors such as crowding. The effect of crowding in vivo emerges from the density of intracellular components. Due to the complexity of the intracellular environment, most studies are based on either in vitro reconstitution or theory. Crowding agent (crowdants) size has been shown to influence polymerization of both actin and microtubules (MTs). Previously, the elongation rates of MT dynamics observed at single filament scale were reported to decrease with increasing concentrations of small but not large crowdants, and this correlated with in vivo viscosity increases. However, the exact nature of the connection between viscosity, crowdant size, nucleation, and MT elongation has remained unclear. Here, we use in vitro reconstitution of bulk MT polymerization kinetics and microscopy to examine the collective effect of crowdant molecular weight, volume occupancy, and viscosity on elongation and spontaneous polymerization. We find MT elongation rates obtained from bulk polymerization decrease in the presence of multiple low-molecular weight (LMW) crowdants, while increasing with high-molecular weight (HMW) crowdants. Lattice Monte Carlo simulations of an effective model of collective polymerization demonstrate reduced polymerization rates arise due to decrease in monomer diffusion due to small-sized crowdants. However, MT polymerization in the absence of nucleators, de novo, shows a crowdant size independence of polymerization rate and critical concentration, depending solely on concentration of the crowdant. In microscopy, we find LMW crowdants result in short but many filaments, while HMW crowdants increase filament density, but have little effect on lengths. The effect of crowdant volume fraction ϕC and size in de novo polymerization match simulations, demonstrating crowdants affect elongation independent of nucleation. Thus, the effect of viscosity on collective MT dynamics, i.e., filament numbers and lengths, shows crowdant size dependence for elongation, but independence for de novo polymerization.

Selective regulation of kinesin-5 function by β-tubulin carboxy-terminal tails

The tubulin code hypothesis predicts that tubulin tails create programs for selective regulation of microtubule-binding proteins, including kinesin motors. However, the molecular mechanisms that determine selective regulation and their relevance in cells are poorly understood. We report selective regulation of budding yeast kinesin-5 motors by the β-tubulin tail. Cin8, but not Kip1, requires the β-tubulin tail for recruitment to the mitotic spindle, creating a balance of both motors in the spindle and efficient mitotic progression. We identify a negatively charged patch in the β-tubulin tail that mediates interaction with Cin8. Using in vitro reconstitution with genetically modified yeast tubulin, we demonstrate that the charged patch of β-tubulin tail increases Cin8 plus-end-directed velocity and processivity. Finally, we determine that the positively charged amino-terminal extension of Cin8 coordinates interactions with the β-tubulin tail. Our work identifies a molecular mechanism underlying selective regulation of closely related kinesin motors by tubulin tails and how this regulation promotes proper function of the mitotic spindle.

Discovery of a novel 2,4-thiazolidinedione derivative as dual inhibitor of β-catenin/TCF4 interaction and tubulin polymerization in colon cancer cells

Hyperactivation of the Wnt/β-catenin signaling pathway has been widely recognized as a pathogenic mechanism for colorectal cancer (CRC). Based on a previously reported lead compound, iCRT14, a series of 2,4-thiazolidinedione derivatives were designed, synthesized, and evaluated in vitro for their antiproliferative activity against colon cancer cells. Compound 15k exhibited the most potent activity against the HCT116 and SW480 cell lines. Compound 15k inhibited Wnt/β-catenin signaling by disrupting the protein-protein interactions between β-catenin and TCF4. Compound 15k simultaneously inhibited tubulin polymerization, disorganized the microtubule network, and arrested the cell cycle at the G2/M phase, offering an additional mechanism of action and 15k induced cell apoptosis by activating caspase-3 and poly(ADP-ribose) polymerase. Additionally, compound 15k inhibited cell migration without affecting the levels of β-catenin protein. These results offer guidance for developing the current series as potential new anticancer therapeutics.

Microtubule Reorganization and Quiescence: an Intertwined Relationship

Quiescence is operationally defined as a reversible proliferation arrest. This cellular state is central to both organism development and homeostasis, and its dysregulation causes many pathologies. The quiescent state encompasses very diverse cellular situations depending on the cell type and its environment. Further, quiescent cell properties evolve with time, a process that is thought to be the origin of aging in multicellular organisms. Microtubules are found in all eukaryotes and are essential for cell proliferation as they support chromosome segregation and intracellular trafficking. Upon proliferation cessation and quiescence establishment, the microtubule cytoskeleton was shown to undergo significant remodeling. The purpose of this review is to examine the literature in search of evidence to determine whether the observed microtubule reorganizations are merely a consequence of quiescence establishment or if they somehow participate in this cell fate decision.

Elongator is a microtubule polymerase selective for polyglutamylated tubulin

Elongator is a tRNA-modifying complex that regulates protein translation. Recently, a moonlighting function of Elongator has been identified in regulating the polarization of the microtubule cytoskeleton during asymmetric cell division. Elongator induces symmetry breaking of the anaphase midzone by selectively stabilizing microtubules on one side of the spindle, contributing to the downstream polarized segregation of cell-fate determinants, and therefore to cell fate determination. Here, we investigate how Elongator controls microtubule dynamics. Elongator binds both to the tip of microtubules and to free GTP-tubulin heterodimers using two different subcomplexes, Elp123 and Elp456, respectively. We show that these activities must be coupled for Elongator to decrease the tubulin critical concentration for microtubule elongation. As a consequence, Elongator increases the growth speed and decreases the catastrophe rate of microtubules. Surprisingly, the Elp456 subcomplex binds to tubulin tails and has strong selectivity towards polyglutamylated tubulin. Hence, microtubules assembled by Elongator become selectively enriched with polyglutamylated tubulin, as observed in vitro, in mouse and Drosophila cell lines, as well as in vivo in Drosophila Sensory Organ Precursor cells. Therefore, Elongator rewrites the tubulin code of growing microtubules, placing it at the core of cytoskeletal dynamics and polarization during asymmetric cell division.

FSD1 inhibits glioblastoma diffuse infiltration through restriction of HDAC6-mediated microtubule deacetylation

The infiltration of glioblastoma multiforme (GBM) is predominantly characterized by diffuse spread, contributing significantly to therapy resistance and recurrence of GBM. In this study, we reveal that microtubule deacetylation, mediated through the downregulation of fibronectin type III and SPRY domain-containing 1 (FSD1), plays a pivotal role in promoting GBM diffuse infiltration. FSD1 directly interacts with histone deacetylase 6 (HDAC6) at its second catalytic domain, thereby impeding its deacetylase activity on α-tubulin and preventing microtubule deacetylation and depolymerization. This inhibitory interaction is disrupted upon phosphorylation of FSD1 at its Ser317 and Ser324 residues by activated CDK5, leading to FSD1 dissociation from microtubules and facilitating HDAC6-mediated α-tubulin deacetylation. Furthermore, increased expression of FSD1 or interference with FSD1 phosphorylation reduces microtubule deacetylation, suppresses invasion of GBM stem cells, and ultimately mitigates tumor infiltration in orthotopic GBM xenografts. Importantly, GBM tissues exhibit diminished levels of FSD1 expression, correlating with microtubule deacetylation and unfavorable clinical outcomes in GBM patients. These findings elucidate the mechanistic involvement of microtubule deacetylation in driving GBM cell invasion and offer potential avenues for managing GBM infiltration.

Axon-specific microtubule regulation drives asymmetric regeneration of sensory neuron axons

Sensory dorsal root ganglion (DRG) neurons have a unique pseudo-unipolar morphology in which a stem axon bifurcates into a peripheral and a central axon, with different regenerative abilities. Whereas peripheral DRG axons regenerate, central axons are unable to regrow. Central axon regeneration can however be elicited by a prior conditioning lesion to the peripheral axon. How DRG axon asymmetry is established remains unknown. Here we developed a rodent in vitro system replicating DRG pseudo-unipolarization and asymmetric axon regeneration. Using this model, we observed that from early development, central DRG axons have a higher density of growing microtubules. This asymmetry was also present in vivo and was abolished by a conditioning lesion that decreased microtubule polymerization of central DRG axons. An axon-specific microtubule-associated protein (MAP) signature, including the severases spastin and katanin and the microtubule regulators CRMP5 and tau, was found and shown to adapt upon conditioning lesion. Supporting its significance, interfering with the DRG MAP signature either in vitro or in vivo readily abolished central-peripheral asymmetries in microtubule dynamics and regenerative ability. In summary, our data unveil that axon-specific microtubule regulation drives asymmetric regeneration of sensory neuron axons.

How does the tubulin code facilitate directed cell migration?

Besides being a component of the cytoskeleton that provides structural integrity to the cell, microtubules also serve as tracks for intracellular transport. As the building units of the mitotic spindle, microtubules distribute chromosomes during cell division. By distributing organelles, vesicles, and proteins, they play a pivotal role in diverse cellular processes, including cell migration, during which they reorganize to facilitate cell polarization. Structurally, microtubules are built up of α/β-tubulin dimers, which consist of various tubulin isotypes that undergo multiple post-translational modifications (PTMs). These PTMs allow microtubules to differentiate into functional subsets, influencing the associated processes. This text explores the current understanding of the roles of tubulin PTMs in cell migration, particularly detyrosination and acetylation, and their implications in human diseases.

Design, Synthesis, and Antiproliferative Activity of Novel Indole/1,2,4-Triazole Hybrids as Tubulin Polymerization Inhibitors

Background/Objectives: New indole/1,2,4-triazole hybrids were synthesized and tested for antiproliferative activity against the NCI 60 cell line as tubulin polymerization inhibitors. Methods: All final compounds, 6a-j and 7a-j were evaluated at a single concentration of 10 µM against a panel of sixty cancer cell lines. Results: Compounds 7a-j, featuring the NO-releasing oxime moiety, exhibited superior anticancer activity to their precursor ketones 6a-j across all tested cancer cell lines. Compounds 6h, 7h, 7i, and 7j were chosen for five-dose evaluations against a comprehensive array of 60 human tumor cell lines. The data showed that all tested compounds had significant anticancer activity throughout the nine tumor subpanels studied, with selectivity ratios ranging from 0.52 to 2.29 at the GI50 level. Compounds 7h and 7j showed substantial anticancer effectiveness against most cell lines across nine subpanels, with GI50 values ranging from 1.85 to 5.76 µM and 2.45 to 5.23 µM. Compounds 6h, 7h, 7i, and 7j were assessed for their inhibitory effects on tubulin polymerization. Conclusions: The results showed that compound 7i, an oxime-based derivative, was the most effective at blocking tubulin, with an IC50 value of 3.03 ± 0.11 µM. This was compared to the standard drug CA-4, which had an IC50 value of 8.33 ± 0.29 µM. Additionally, cell cycle analysis and apoptosis assays were performed for compound 7i. Molecular computational investigations have been performed to examine the binding mode of the most effective compounds to the target enzyme.

Doublecortin restricts neuronal branching by regulating tubulin polyglutamylation

Doublecortin is a neuronal microtubule-associated protein that regulates microtubule structure in neurons. Mutations in Doublecortin cause lissencephaly and subcortical band heterotopia by impairing neuronal migration. We use CRISPR/Cas9 to knock-out the Doublecortin gene in induced pluripotent stem cells and differentiate the cells into cortical neurons. DCX-KO neurons show reduced velocities of nuclear movements and an increased number of neurites early in neuronal development, consistent with previous findings. Neurite branching is regulated by a host of microtubule-associated proteins, as well as by microtubule polymerization dynamics. However, EB comet dynamics are unchanged in DCX-KO neurons. Rather, we observe a significant reduction in α-tubulin polyglutamylation in DCX-KO neurons. Polyglutamylation levels and neuronal branching are rescued by expression of Doublecortin or of TTLL11, an α-tubulin glutamylase. Using U2OS cells as an orthogonal model system, we show that DCX and TTLL11 act synergistically to promote polyglutamylation. We propose that Doublecortin acts as a positive regulator of α-tubulin polyglutamylation and restricts neurite branching. Our results indicate an unexpected role for Doublecortin in the homeostasis of the tubulin code.

Synergism between TLR4 and B. infantis in the development of the premature intestine

BACKGROUND

Intestinal microbiota has a role in early life maturation including maturation of intestinal immune function. However, the interaction of the TLR4 with colonizing bacteria in intestinal development is incompletely understood.

METHODS

An established human immature small intestinal cell line, human fetal intestinal organoids, and wild-type (WT) and TLR4 gene knockout (TLR4 -/-) neonatal mice were used to test the synergism between the innate immune receptor TLR4 and postbiotics from Bifidobacteria longum subsp. infantis (B. infantis) in development of the premature intestine.

RESULTS

TLR4-mediated postbiotics induced immature enterocyte proliferation and filamentous actin (F-actin) maturation both at the mRNA and protein levels. Proliferation of mRNA levels increased in wild-type mice but not in TLR4 -/- mice fed by postbiotics, both in the ileum and colon. Postbiotics can also change tight junction distribution in WT neonatal colon but not in TLR4 -/- mice.

CONCLUSIONS

Our data suggest a novel regulation of intestinal development by a synergistic role of the innate immune receptor TLR4 and early life colonizing bacteria, such as B. infantis. This study should provide new insights into the mechanisms of intestinal maturation as well as opportunities to target novel approaches to NEC prevention and treatment.

IMPACT

The innate immune system and postbiotics affect immature intestinal development. The innate immune receptor TLR4 prevention of NEC. Mechanism of prevention of NEC. This is the first time this has been demonstrated in human fetal intestine. In vitro process for future clinical studies for prevention of NEC.

Colchicine for the primary prevention of cardiovascular events

BACKGROUND

Atherosclerotic cardiovascular diseases (ACVDs), a condition characterised by lipid accumulation in arterial walls, which is often exacerbated by chronic inflammation disorders, is the major cause of mortality and morbidity worldwide. Colchicine, with its first medicinal use in ancient Egypt, is an inexpensive drug with anti-inflammatory properties. However, its role in primary prevention of ACVDs in the general population remains unknown.

OBJECTIVES

To assess the clinical benefits and harms of colchicine as primary prevention of cardiovascular outcomes in the general population.

SEARCH METHODS

We searched the Cochrane Heart Specialised Register, the Cochrane Central Register of Controlled Trials (CENTRAL), Ovid MEDLINE (including In-Process & Other Non-Indexed Citations), Ovid Embase, Web of Science, and LILACS. We searched ClinicalTrials.gov and WHO ICTRP for ongoing and unpublished studies. We also scanned the reference lists of relevant included studies, reviews, meta-analyses, and health technology reports to identify additional studies. There were no limitations on language, date of publication, or study setting. The search results were updated on 31 May 2023.

SELECTION CRITERIA

Randomised controlled trials (RCTs) in any setting, recruiting adults without pre-existing cardiovascular disease. We included trials that compared colchicine versus placebo, non-steroidal anti-inflammatory drugs, corticosteroids, immunomodulating drugs, or usual care. Our primary outcomes were all-cause mortality, non-fatal myocardial infarction, stroke, and adverse events.

DATA COLLECTION AND ANALYSIS

Two or more review authors independently selected studies, extracted data, and performed risk of bias and GRADE assessments.

MAIN RESULTS

We identified 15 RCTs (1721 participants randomised; 1412 participants analysed) with follow-up periods ranging from 4 to 728 weeks. The intervention was oral colchicine compared with placebo, immunomodulating drugs, or usual care or no treatment. Due to biases and imprecision, the evidence was very uncertain for all outcomes. All trials but one had a high risk of bias. Five out of seven meta-analyses included fewer than six trials (71.4%). The objectives of the review were to assess cardiovascular outcomes in the general population, but many of the included trials focused on liver disease. Colchicine compared to placebo Colchicine may reduce all-cause mortality compared to placebo in primary prevention, but the evidence is very uncertain (risk ratio (RR) 0.68, 95% confidence interval (CI) 0.51 to 0.91; 6 studies, 463 participants; very low-certainty evidence; number needed to treat for an additional beneficial outcome (NNTB) 11, 95% CI 6 to 67). Colchicine may result in little to no difference in non-fatal myocardial infarction, but the evidence is very uncertain (RR 0.87, 95% CI 0.41 to 1.82; 1 study, 100 participants; very low-certainty evidence). Colchicine may not reduce the incidence of stroke, but the evidence is very uncertain (RR 2.43, 95% CI 0.67 to 8.86; 1 study, 100 participants; very low-certainty evidence). Regarding adverse events, colchicine may increase the incidence of diarrhoea (RR 3.99, 95% CI 1.44 to 11.06; 8 studies, 605 participants; very low-certainty evidence; number needed to treat for an additional harmful outcome (NNTH) 10, 95% CI 6 to 17), and may have little to no effect on neurological outcomes such as seizure or mental confusion (RR 0.72, 95% CI 0.31 to 1.66; 2 studies, 155 participants; very low-certainty evidence), but the evidence is very uncertain. The effect of colchicine on cardiovascular mortality is also very uncertain (RR 1.27, 95% CI 0.03 to 62.43; 2 studies, 160 participants; very low-certainty evidence). Colchicine may not reduce post-cardiac procedure atrial fibrillation, but the evidence is very uncertain (RR 0.74, 95% CI 0.25 to 2.19; 1 study, 100 participants). We found no trials reporting on pericardial effusion, peripheral artery disease, heart failure, or unstable angina. Colchicine compared to methotrexate (immunomodulating drug) Colchicine may result in little to no difference in all-cause mortality compared to methotrexate, but the evidence is very uncertain (RR 0.42, 95% CI 0.12 to 1.51; 1 study, 85 participants; very low-certainty evidence). We found no trials reporting other cardiovascular outcomes or adverse events for this comparison. Colchicine compared to usual care or no treatment The evidence is very uncertain about the effect of colchicine compared with usual care on all-cause mortality in primary prevention (RR 1.07, 95% CI 0.90 to 1.27; 2 studies, 729 participants; very low-certainty evidence). Regarding adverse events, colchicine may increase the incidence of diarrhoea compared to usual care, but the evidence is very uncertain (RR 3.32, 95% CI 1.56 to 7.03; 2 studies, 729 participants; very low-certainty evidence; NNTH 18, 95% CI 12 to 42). No trials reported other cardiovascular outcomes for this comparison.

AUTHORS' CONCLUSIONS

This Cochrane review evaluated the clinical benefits and harms of using colchicine for the primary prevention of cardiovascular events in the general population. Comparisons were made against placebo, immunomodulating medications, or usual care or no treatment. However, the certainty of the evidence for the predefined outcomes was very low, highlighting the pressing need for high-quality, rigorous studies to ascertain colchicine's clinical impact definitively. We identified numerous biases and inaccuracies in the included studies, limiting their generalisability and precluding a conclusive determination of colchicine's efficacy in preventing cardiovascular events. The existing evidence regarding colchicine's potential cardiovascular benefits or harms for primary prevention is inconclusive owing to the limitations inherent in the current studies. More robust clinical trials are needed to bridge this evidence gap effectively.

Design, synthesis, and antitumor evaluation of quinazoline-4-tetrahydroquinoline chemotypes as novel tubulin polymerization inhibitors targeting the colchicine site

We designed, synthesized, and evaluated the antitumor activity of a series of novel quinazoline-4-(6-methoxytetrahydroquinoline) analogues. Among the tested compounds, 4a4 exhibited the most potent antiproliferative activities across four human cancer cell lines with half-maximal inhibitory concentration (IC50) values ranging from 0.4 to 2.7 nM, more potent than the lead compound. The 2.71 Å resolution co-crystal structure of 4a4 with tubulin (PDB code: 8YER) confirmed its critical binding at the colchicine site. Moreover, 4a4 inhibited the polymerization of tubulin, colony formation, and tumor cell migration, while inducing G2/M phase arrest and apoptosis. In vivo, 4a4 significantly delayed primary tumor growth in the SKOV3 xenograft model without obvious side effect. Our research enhances the structure-activity relationships (SARs) understanding of the quinazoline-4-tetrahydroquinoline scaffold and provides new insights for potential structural optimization and the development of novel colchicine binding site inhibitors (CBSIs).

Structural switching of tubulin in the microtubule lattice

Microtubule (MT) dynamic instability, a cycle of growth, catastrophe, shrinkage and rescue, is driven by the switching of tubulin between two structural states, one stabilised by GTP and the other by GDP. Recent work has uncovered the ancient origins of this structural switch and revealed further fundamental elements of microtubule dynamic instability, whereby switching can be brought about by a range of allosteric effectors, propagate deep within the lattice of assembled MTs, and profoundly affect MT function. Here, we review evidence for structural switching within the MT lattice and discuss current ideas about its mechanisms.

Non-canonical CDK6 activity promotes cilia disassembly by suppressing axoneme polyglutamylation

Tubulin polyglutamylation is a posttranslational modification that occurs primarily along the axoneme of cilia. Defective axoneme polyglutamylation impairs cilia function and has been correlated with ciliopathies, including Joubert Syndrome (JBTS). However, the precise mechanisms regulating proper axoneme polyglutamylation remain vague. Here, we show that cyclin-dependent kinase 6 (CDK6), but not its paralog CDK4, localizes to the cilia base and suppresses axoneme polyglutamylation by phosphorylating RAB11 family interacting protein 5 (FIP5) at site S641, a critical regulator of cilia import of glutamylases. S641 phosphorylation disrupts the ciliary recruitment of FIP5 and its association with RAB11, thereby reducing the ciliary import of glutamylases. Encouragingly, the FDA-approved CDK4/6 inhibitor Abemaciclib can effectively restore cilia function in JBTS cells with defective glutamylation. In summary, our study elucidates the regulatory mechanisms governing axoneme polyglutamylation and suggests that developing CDK6-specific inhibitors could be a promising therapeutic strategy to enhance cilia function in ciliopathy patients.

Structure of blood cell-specific tubulin and demonstration of dimer spacing compaction in a single protofilament

Microtubule (MT) function plasticity originates from its composition of α- and β-tubulin isotypes and the posttranslational modifications of both subunits. Aspects such as MT assembly dynamics, structure, and anticancer drug binding can be modulated by αβ-tubulin heterogeneity. However, the exact molecular mechanism regulating these aspects is only partially understood. A recent insight is the discovery of expansion and compaction of the MT lattice, which can occur via fine modulation of dimer longitudinal spacing mediated by GTP hydrolysis, taxol binding, protein binding, or isotype composition. Here, we report the first structure of the blood cell-specific α1/β1-tubulin isolated from the marginal band of chicken erythrocytes (ChET) determined to a resolution of 3.2 Å by cryo-EM. We show that ChET rings induced with cryptophycin-52 (Cp-52) are smaller in diameter than HeLa cell line tubulin (HeLaT) rings induced with Cp-52 and composed of the same number of heterodimers. We observe compacted interdimer and intradimer curved protofilament interfaces, characterized by shorter distances between ChET subunits and accompanied by conformational changes in the β-tubulin subunit. The compacted ChET interdimer interface brings more residues near the Cp-52 binding site. We measured the Cp-52 apparent binding affinities of ChET and HeLaT by mass photometry, observing small differences, and detected the intermediates of the ring assembly reaction. These findings demonstrate that compaction/expansion of dimer spacing can occur in a single protofilament context and that the subtle structural differences between tubulin isotypes can modulate tubulin small molecule binding.

Recent advances of selenized tubulin inhibitors in cancer therapy

Cancer treatment always a huge challenge amidst the resistance and relapse caused by the various treatments. Inhibitors targeting mitosis have been considered as promising therapeutic drugs in clinic, of which tubulins play an important role. Selenium (Se) as an essential microelement in humans and animals, playing a crucial role in the formation of anti-oxidase (glutathione peroxidase) and selenoprotein, also attracted broad attention in cancer therapy. Because the introduction of Se atom could change the length and angle of chemical bond and alter their functional properties, regulating selenized chemotherapeutics has become one of the hot spots. However, little attention has been paid to studying the combination of Se and tubulin inhibitors. Herein, we review the latest research results of selenized tubulin inhibitors in cancer therapy, including its mechanisms, categories and biological activities, providing a theoretical basis for different selenized microtubules inhibitors therapies.

Tubulin acetyltransferases access and modify the microtubule luminal K40 residue through anchors in taxane-binding pockets

Acetylation at α-tubulin K40 is the sole post-translational modification preferred to occur inside the lumen of hollow cylindrical microtubules. However, how tubulin acetyltransferases access the luminal K40 in micrometer-long microtubules remains unknown. Here, we use cryo-electron microscopy and single-molecule reconstitution assays to reveal the enzymatic mechanism for tubulin acetyltransferases to modify K40 in the lumen. One tubulin acetyltransferase spans across the luminal lattice, with the catalytic core docking onto two α-tubulins and the enzyme's C-terminal domain occupying the taxane-binding pockets of two β-tubulins. The luminal accessibility and enzyme processivity of tubulin acetyltransferases are inhibited by paclitaxel, a microtubule-stabilizing chemotherapeutic agent. Characterizations using recombinant tubulins mimicking preacetylated and postacetylated K40 show the crosstalk between microtubule acetylation states and the cofactor acetyl-CoA in enzyme turnover. Our findings provide crucial insights into the conserved multivalent interactions involving α- and β-tubulins to acetylate the confined microtubule lumen.