Structure and function of distal and subdistal appendages of the mother centriole.

Centrosomes are composed of centrioles surrounded by pericentriolar material. The two centrioles in G1 phase are distinguished by the localization of their appendages in the distal and subdistal regions; the centriole possessing both types of appendage is older and referred to as the mother centriole, whereas the other centriole lacking appendages is the daughter centriole. Both distal and subdistal appendages in vertebrate cells consist of multiple proteins assembled in a hierarchical manner. Distal appendages function mainly in the initial process of ciliogenesis, and subdistal appendages are involved in microtubule anchoring, mitotic spindle regulation and maintenance of ciliary signaling. Mutations in genes encoding components of both appendage types are implicated in ciliopathies and developmental defects. In this Review, we discuss recent advances in knowledge regarding the composition and assembly of centriolar appendages, as well as their roles in development and disease.

SCG10 is required for peripheral axon maintenance and regeneration in mice.

Proper microtubule dynamics are critical for neuronal morphogenesis and functions, and their dysregulation results in neurological disorders and regeneration failure. Superior cervical ganglion-10 (SCG10, also known as stathmin-2 or STMN2) is a well-known regulator of microtubule dynamics in neurons, but its functions in the peripheral nervous system remain largely unknown. Here, we show that Scg10 knockout mice exhibit severely progressive motor and sensory dysfunctions with significant sciatic nerve myelination deficits and neuromuscular degeneration. Additionally, increased microtubule stability, shown by a significant increase in tubulin acetylation and decrease in tubulin tyrosination, and decreased axonal transport were observed in Scg10 knockout dorsal root ganglion (DRG) neurons. Furthermore, SCG10 depletion impaired axon regeneration in both injured mouse sciatic nerve and cultured DRG neurons following replating, and the impaired axon regeneration was found to be induced by a lack of SCG10-mediated microtubule dynamics in the neurons. Thus, our results highlight the importance of SCG10 in peripheral axon maintenance and regeneration.

Gender differences in the relationship between serum uric acid and the long-term prognosis in heart failure: a nationwide study.

BACKGROUND: Serum uric acid (SUA) is an important pathogenetic and prognostic factor for heart failure (HF). Gender differences are apparent in HF. Furthermore, gender differences also exist in the association between SUA and prognosis in various cardiovascular diseases. However, the gender difference for SUA in the prediction of long-term prognosis in HF is still ambiguous. METHODS: A total of 1593 HF patients (897 men, 696 women) from the National Health and Nutrition Examination Survey (NHANES) 1999-2018 cycle were enrolled in our final analysis. Participants were categorized according to gender-specific SUA tertile. We assessed the association between SUA and long-term prognosis of HF patients, defined as all-cause mortality and cardiovascular mortality, in different genders via Kaplan-Meier curve analysis, Cox proportional hazard model, and Fine-Gray competing risk model. The restricted cubic spline (RCS) was performed to investigate the dose-response relationship between SUA and outcomes. RESULTS: Gender differences exist in demographic characteristics, clinical parameters, laboratory tests, and medication of HF patients. After a median follow-up of 127 months (95% CI 120-134 months), there were 853 all-cause deaths (493 events in men, 360 events in women) and 361 cardiovascular deaths (206 events in men, 155 events in women). Kaplan-Meier analysis showed that SUA had gender difference in the prediction of cardiovascular mortality (Log-rank p < 0.001, for male, Log-rank p = 0.150, for female), but not in all-cause mortality. Multivariate Cox regression analysis revealed that elevated SUA levels were associated with higher all-cause mortality and cardiovascular mortality in men (HR 1.11, 95% CI 1.05-1.18, p < 0.001, for all-cause death; HR 1.18, 95% CI 1.09-1.28, p < 0.001, for cardiovascular death), but not in women (HR 1.05, 95% CI 0.98-1.12, p = 0.186, for all-cause death; HR 1.01, 95% CI 0.91-1.12, p = 0.902, for cardiovascular death). Even using non-cardiovascular death as a competitive risk, adjusted Fine-Gray model also illustrated that SUA was an independent predictor of cardiovascular death in men (SHR 1.17, 95% CI 1.08-1.27, p < 0.001), but not in women (SHR 0.98, 95% CI 0.87 - 1.10, p = 0.690). CONCLUSIONS: Gender differences in the association between SUA and long-term prognosis of HF existed. SUA was an independent prognostic predictor for long-term outcomes of HF in men, but not in women.

EI24 promotes cell adaption to ER stress by coordinating IRE1 signaling and calcium homeostasis.

The endoplasmic reticulum (ER) is a subcellular organelle crucial for protein folding and calcium storage. Accumulation of unfolded proteins or calcium depletion causes ER stress. Deficiency of ER stress adaptation leads to apoptosis, which is associated with several human disorders. Here, we reveal that ER transmembrane protein EI24 promotes cell adaptation to ER stress by coordinating the IRE1 branch of the unfolded protein response (UPR) and calcium signaling. Under nonstressed conditions, EI24 binds to the kinase domain of IRE1 to inhibit its activation. Upon ER stress, EI24 disassociates from IRE1 to permit UPR activation, and meanwhile targets IP3R1 to prevent ER calcium depletion, which together promote cell adaptation to ER stress. EI24 knockout causes failure of ER stress adaptation and apoptosis. Thus, EI24 is a novel anti-apoptotic factor implicated in ER stress signaling.

Active fluorescent modulation for low-noise super-resolution microscopy.

Extracting the position of individual molecular probes with high precision is the basis and core of super-resolution microscopy. However, with the expectation of low-light conditions in life science research, the signal-to-noise ratio (SNR) decreases and signal extraction faces a great challenge. Here, based on temporally modulating the fluorescence emission at certain periodical patterns, we achieved super-resolution imaging with high sensitivity by largely suppressing the background noise. We propose simple bright-dim (BD) fluorescent modulation and delicate control by phase-modulated excitation. We demonstrate that the strategy can effectively enhance signal extraction in both sparsely and densely labeled biological samples, and thus improve the efficiency and precision of super-resolution imaging. This active modulation technique is generally applicable to various fluorescent labels, super-resolution techniques, and advanced algorithms, allowing a wide range of bioimaging applications.

Enhancing Weak-Signal Extraction for Single-Molecule Localization Microscopy.

Single-molecule localization microscopy (SMLM) has been widely used in biological imaging due to its ultrahigh spatial resolution. However, due to the strategy of reducing photodamage to living cells, the fluorescence signals of emitters are usually weak and the detector noises become non-negligible, which leads to localization misalignments and signal losses, thus deteriorating the imaging capability of SMLM. Here, we propose an active modulation method to control the fluorescence of the probe emitters. It actually marks the emitters with artificial blinking character, which directly distinguishes weak signals from multiple detector noises. We demonstrated from simulations and experiments that this method improves the signal-to-noise ratio by about 10 dB over the non-modulated method and boosts the sensitivity of single-molecule localization down to -4 dB, which significantly reduces localization misalignments and signal losses in SMLM. This signal-noise decoupling strategy is generally applicable to the super-resolution system with versatile labeled probes to improve their imaging capability. We also showed its application to the densely labeled sample, showing its flexibility in super-resolution nanoscopy.

CCDC102B functions in centrosome linker assembly and centrosome cohesion.

The proteinaceous centrosome linker is an important structure that allows the centrosome to function as a single microtubule-organizing center (MTOC) in interphase cells. However, the assembly mechanism of the centrosome linker components remains largely unknown. In this study, we identify CCDC102B as a new centrosome linker protein that is required for maintaining centrosome cohesion. CCDC102B is recruited to the centrosome by C-Nap1 (also known as CEP250) and interacts with the centrosome linker components rootletin and LRRC45. CCDC102B decorates and facilitates the formation of rootletin filaments. Furthermore, CCDC102B is phosphorylated by Nek2A (an isoform encoded by NEK2) and is disassociated from the centrosome at the onset of mitosis. Together, our findings reveal a molecular role for CCDC102B in centrosome cohesion and centrosome linker assembly.This article has an associated First Person interview with the first authors of the paper.

CCDC74A/B are K-fiber crosslinkers required for chromosomal alignment.

BACKGROUND: Spindle microtubule organization, regulated by microtubule-associated proteins, is critical for cell division. Proper organization of kinetochore fiber (K-fiber), connecting spindle poles and kinetochores, is a prerequisite for precise chromosomal alignment and faithful genetic material transmission. However, the mechanisms of K-fiber organization and dynamic maintenance are still not fully understood. RESULTS: We reveal that two previously uncharacterized coiled-coil domain proteins CCDC74A and CCDC74B (CCDC74A/B) are spindle-localized proteins in mammalian cells. They bind directly to microtubules through two separate domains and bundle microtubules both in vivo and in vitro. These functions are required for K-fiber organization, bipolar spindle formation, and chromosomal alignment. Moreover, CCDC74A/B form homodimers in vivo, and their self-association activity is necessary for microtubule bundling and K-fiber formation. CONCLUSIONS: We characterize CCDC74A and CCDC74B as microtubule-associated proteins that localize to spindles and are important K-fiber crosslinkers required for bipolar spindle formation and chromosome alignment.

Trip6 promotes dendritic morphogenesis through dephosphorylated GRIP1-dependent myosin VI and F-actin organization.

Thyroid receptor-interacting protein 6 (Trip6), a multifunctional protein belonging to the zyxin family of LIM proteins, is involved in various physiological and pathological processes, including cell migration and tumorigenesis. However, the role of Trip6 in neurons remains unknown. Here, we show that Trip6 is expressed in mouse hippocampal neurons and promotes dendritic morphogenesis. Through interaction with the glutamate receptor-interacting protein 1 (GRIP1) and myosin VI, Trip6 is crucial for the total dendritic length and the number of primary dendrites in cultured hippocampal neurons. Trip6 depletion reduces F-actin content and impairs dendritic morphology, and this phenocopies GRIP1 or myosin VI knockdown. Furthermore, phosphorylation of GRIP1(956T) by AKT1 inhibits the interaction between GRIP1 and myosin VI, but facilitates GRIP1 binding to 14-3-3 protein, which is required for regulating F-actin organization and dendritic morphogenesis. Thus, the Trip6-GRIP1-myosin VI interaction and its regulation on F-actin network play a significant role in dendritic morphogenesis.

Characterization of actin and tubulin promoters from two sap-sucking pests, Nilaparvata lugens (Stål) and Nephotettix cincticeps (Uhler).

The brown planthopper, Nilaparvata lugens (N. lugens, Hemiptera: Delphacidae), and the green rice leafhopper, Nephotettix cincticeps (N. cincticeps, Hemiptera: Cicadellidae), two sap-sucking feeders, have caused many destructive agricultural disasters in East Asia, as they can bring diseases like 'hopper burn' and transmit plant viruses. Recently, continuously-cultured cell lines from both insects have been reported. However, exogenous protein expression systems have not yet been established. Here, we identified thirteen tubulin genes and three actin genes from N. lugens, and one tubulin gene and two actin genes from N. cincticeps. Furthermore, putative promoter regions of these genes were analyzed by bioinformatic approaches and 5'-RACE assay, and the promoter strength was evaluated by driving the enhanced green fluorescent protein expression in three insect cell lines, S2, Sf9, and BmN. Finally, we identified three effective promoters (Nl_αTub1 promoter, Nl_act3 promoter, and Nc_act1 promoter) among all candidates we screened. The Nc_act1 promoter showed the strongest activity, while the Nl_αTub1 promoter only worked in S2 cells. In conclusion, we identified and functionally characterized three native promoters from N. lugens and N.cincticeps, which would facilitate the establishment of exogenous protein expression systems suitable for these two insect pests.

SCG10 promotes non-amyloidogenic processing of amyloid precursor protein by facilitating its trafficking to the cell surface.

The processing of amyloid precursor protein (APP) is a key event in the pathogenesis of Alzheimer's disease. As certain cleavage pathways tend to occur in particular subcellular compartments, the processing of APP is greatly influenced by factors that regulate its trafficking. Here we report that SCG10 directly interacts with the KFFEQ motif of the APP intracellular domain and promotes the non-amyloidogenic processing of the APP. Knockdown of SCG10 led to decreases in α cleavage products, sAPPα and CTFα, while increases of both Aß1-40 and Aß1-42. Elevation of SCG10 induced APP accumulation in post-Golgi vesicles and on the cell surface by facilitating its secretory pathway. In addition, the APP processing was dependent on the palmitoylation-mediated membrane-anchoring of SCG10. Furthermore, elevation of SCG10 reduced Aß accumulation and amyloid plaque formation in the hippocampus of APPswe/PS1dE9 mice. Taken together, these results show that SCG10 has a potential role in preventing and treating Alzheimer's disease.

14-3-3 proteins interact with neurofilament protein-L and regulate dynamic assembly of neurofilaments.

Neurofilament protein-L (NF-L) is the core component of neurofilaments. Recent studies indicate that the NF-L mutations reported in human Charcot-Marie-Tooth (CMT) disease lead to the formation of NF-L aggregates and result in axon degeneration of motor and sensory neurons, which are thought to be the cause of CMT disease type 2E. In the present study, we investigated the dynamic regulation of NF-L assembly and the mechanism of aggregate formation of CMT NF-L mutants. We report that 14-3-3 proteins interact with NF-L in a phosphorylation-dependent manner. Investigation of mutations of phospho-serine sites at the head domain of NF-L revealed that several phosphorylation sites, particularly Ser43 and Ser55, were important for 14-3-3 binding. 14-3-3 overexpression resulted in a significant increase in the dynamic exchange rate of NF-L subunits and induced striking disassembly of neurofilaments. CMT NF-L mutants, particularly those with mutations in the Pro8 and Pro22 sites of the NF-L head domain, led to substantially diminished interaction between 14-3-3 and NF-L, which resulted in the formation of NF-L aggregates and the disruption of the neurofilament co-assembly of NF-L and NF-M. However, aggregate formation in CMT NF-L mutants was downregulated by 14-3-3 overexpression. Taken together, these results suggest the important role of 14-3-3 in the dynamic regulation of NF-L assembly, and in the capacity to prevent the formation of NF-L aggregates. Thus, the 14-3-3 proteins are a possible molecular target for CMT disease therapy.

Calumenin and fibulin-1 on tumor metastasis: Implications for pharmacology.

Tumor metastasis is a key cause of cancer mortality, and inhibiting migration of cancer cells is one of the major directions of anti-metastatic drug development. Calumenin and fibulin-1 are two extracellular proteins that synergistically inhibit cell migration and tumor metastasis, and could potentially be served as targets for pharmacological research of anti-metastatic drugs. This review briefly introduces the multi-function of these two proteins, and discusses the mechanism of how they regulate cell migration and tumor metastasis.

Cep57 protein is required for cytokinesis by facilitating central spindle microtubule organization.

Cytokinesis is the final stage of cell division in which the cytoplasm of a cell is divided into two daughter cells after the segregation of genetic material, and the central spindle and midbody are considered to be the essential structures required for the initiation and completion of cytokinesis. Here, we determined that the centrosome protein Cep57, which is localized to the central spindle and midbody, acts as a spindle organizer and is required for cytokinesis. Depletion of Cep57 disrupted microtubule assembly of the central spindle and further led to abnormal midbody localization of MKLP1, Plk1, and Aurora B, which resulted in cytokinesis failure and the formation of binuclear cells. Furthermore, we found that Cep57 directly recruited Tektin 1 to the midbody matrix to regulate microtubule organization. Thus, our data reveal that Cep57 is essential for cytokinesis via regulation of central spindle assembly and formation of the midbody.

BmCREC is an endoplasmic reticulum (ER) resident protein and required for ER/Golgi morphology.

Silkworm posterior silkgland is a model for studying intracellular trafficking. Here, using this model, we identify several potential cargo proteins of BmKinesin-1 and focus on one candidate, BmCREC. BmCREC (also known as Bombyx mori DNA supercoiling factor, BmSCF) was previously proposed to supercoil DNA in the nucleus. However, we show here that BmCREC is localized in the ER lumen. Its C-terminal tetrapeptide HDEF is recognized by the KDEL receptor, and subsequently it is retrogradely transported by coat protein I (COPI) vesicles to the ER. Lacking the HDEF tetrapeptide of BmCREC or knocking down COPI subunits results in decreased ER retention and simultaneously increased secretion of BmCREC. Furthermore, we find that BmCREC knockdown markedly disrupts the morphology of the ER and Golgi apparatus and leads to a defect of posterior silkgland tube expansion. Together, our results clarify the ER retention mechanism of BmCREC and reveal that BmCREC is indispensable for maintaining ER/Golgi morphology.

Securin acetylation prevents precocious separase activation and premature sister chromatid separation.

Lysine acetylation of non-histone proteins plays crucial roles in many cellular processes. In this study, we examine the role of lysine acetylation during sister chromatid separation in mitosis. We investigate the acetylation of securin at K21 by cell-cycle-dependent acetylome analysis and uncover its role in separase-triggered chromosome segregation during mitosis. Prior to the onset of anaphase, the acetylated securin via TIP60 prevents its degradation by the APC/CCDC20-mediated ubiquitin-proteasome system. This, in turn, restrains precocious activation of separase and premature separation of sister chromatids. Additionally, the acetylation-dependent stability of securin is also enhanced by its dephosphorylation. As anaphase approaches, HDAC1-mediated deacetylation of securin promotes its degradation, allowing released separase to cleave centromeric cohesin. Blocking securin deacetylation leads to longer anaphase duration and errors in chromosome segregation. Thus, this study illustrates the emerging role of securin acetylation dynamics in mitotic progression and genetic stability.

Dual roles of CCDC102A in governing centrosome duplication and cohesion.

In animal cells, the dysregulation of centrosome duplication and cohesion maintenance leads to abnormal spindle assembly and chromosomal instability, contributing to developmental disorders and tumorigenesis. However, the molecular mechanisms involved in maintaining accurate centrosome number control and tethering are not fully understood. Here, we identified coiled-coil domain-containing 102A (CCDC102A) as a centrosomal protein exhibiting a barrel-like structure in the proximal regions of parent centrioles, where it prevents centrosome overduplication by restricting interactions between Cep192 and Cep152 on centrosomes, thereby ensuring bipolar spindle formation. Additionally, CCDC102A regulates the centrosome linker by recruiting and binding C-Nap1; it is removed from the centrosome after Nek2A-mediated phosphorylation at the onset of mitosis. Overall, our results indicate that CCDC102A participates in controlling centrosome number and maintaining centrosome cohesion, suggesting that a well-tuned system regulates centrosome structure and function throughout the cell cycle.

Transcriptomic analysis reveals the potential crosstalk genes and immune relationship between Crohn's disease and atrial fibrillation.

Background: At present, there is a paucity of research on the link between Crohn's disease (CD) and atrial fibrillation (AF). Nevertheless, both ailments are thought to entail inflammatory and autoimmune processes, and emerging evidence indicates that individuals with CD may face an elevated risk of AF. To shed light on this issue, our study seeks to explore the possibility of shared genes, pathways, and immune cells between these two conditions. Methods: We retrieved the gene expression profiles of both CD and AF from the Gene Expression Omnibus (GEO) database and subjected them to analysis. Afterward, we utilized the weighted gene co-expression network analysis (WGCNA) to identify shared genes, which were then subjected to further Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analyses. Furthermore, we employed a rigorous analytical approach by screening hub genes through both least absolute shrinkage and selection operator (LASSO) regression and support vector machine (SVM), and subsequently constructing a receiver operating characteristic (ROC) curve based on the screening outcomes. Finally, we utilized single-sample gene set enrichment analysis (ssGSEA) to comprehensively evaluate the levels of infiltration of 28 immune cells within the expression profile and their potential association with the shared hub genes. Results: Using the WGCNA method, we identified 30 genes that appear to be involved in the pathological progression of both AF and CD. Through GO enrichment analysis on the key gene modules derived from WGCNA, we observed a significant enrichment of pathways related to major histocompatibility complex (MHC) and antigen processing. By leveraging the intersection of LASSO and SVM algorithms, we were able to pinpoint two overlapping genes, namely CXCL16 and HLA-DPB1. Additionally, we evaluated the infiltration of immune cells and observed the upregulation of CD4+ and CD8+ T cells, as well as dendritic cells in patients with AF and CD. Conclusions: By employing bioinformatics tools, we conducted an investigation with the objective of elucidating the genetic foundations that connect AF and CD. This study culminated in the identification of CXCL16 and HLA-DPB1 as the most substantial genes implicated in the development of both disorders. Our findings suggest that the immune responses mediated by CD4+ and CD8+ T cells, along with dendritic cells, may hold a crucial role in the intricate interplay between AF and CD.

PACSIN1, a Tau-interacting protein, regulates axonal elongation and branching by facilitating microtubule instability.

Tau is a major member of the neuronal microtubule-associated proteins. It promotes tubulin assembly and stabilizes axonal microtubules. Previous studies have demonstrated that Tau forms cross-bridges between microtubules, with some particles located on cross-bridges, suggesting that some proteins interact with Tau and might be involved in regulating Tau-related microtubule dynamics. This study reports that PACSIN1 interacts with Tau in axon. PACSIN1 blockade results in impaired axonal elongation and a higher number of primary axonal branches in mouse dorsal root ganglia neurons, which is induced by increasing the binding ability of Tau to microtubules. In PACSIN1-blocked dorsal root ganglia neurons, a greater amount of Tau is inclined to accumulate in the central domain of growth cones, and it promotes the stability of the microtubule network. Taken together, these results suggest that PACSIN1 is an important Tau binding partner in regulating microtubule dynamics and forming axonal plasticity.

Traumatic scratch injury in astrocytes triggers calcium influx to activate the JNK/c-Jun/AP-1 pathway and switch on GFAP expression.

Astrocyte activation is a hallmark of central nervous system injuries resulting in glial scar formation (astrogliosis). The activation of astrocytes involves metabolic and morphological changes with complex underlying mechanisms, which should be defined to provide targets for astrogliosis intervention. Astrogliosis is usually accompanied by an upregulation of glial fibrillary acidic protein (GFAP). Using an in vitro scratch injury model, we scratched primary cultures of cerebral cortical astrocytes and observed an influx of calcium in the form of waves spreading away from the wound through gap junctions. Using the calcium blocker BAPTA-AM and the JNK inhibitor SP600125, we demonstrated that the calcium wave triggered the activation of JNK, which then phosphorylated the transcription factor c-Jun to facilitate the binding of AP-1 to the GFAP gene promoter to switch on GFAP upregulation. Blocking calcium mobilization with BAPTA-AM in an in vivo stab wound model reduced GFAP expression and glial scar formation, showing that the calcium signal, and the subsequent regulation of downstream signaling molecules, plays an essential role in brain injury response. Our findings demonstrated that traumatic scratch injury to astrocytes triggered a calcium influx from the extracellular compartment and activated the JNK/c-Jun/AP-1 pathway to switch on GFAP expression, identifying a previously unreported signaling cascade that is important in astrogliosis and the physiological response following brain injury.