Actin cytoskeleton in the control of vesicle transport, cytoplasmic organization, and pollen tube tip growth.

Pollen tubes extend rapidly via tip growth. This process depends on a dynamic actin cytoskeleton, which has been implicated in controlling organelle movements, cytoplasmic streaming, vesicle trafficking, and cytoplasm organization in pollen tubes. In this update review, we describe the progress in understanding the organization and regulation of the actin cytoskeleton and the function of the actin cytoskeleton in controlling vesicle traffic and cytoplasmic organization in pollen tubes. We also discuss the interplay between ion gradients and the actin cytoskeleton that regulates the spatial arrangement and dynamics of actin filaments and the organization of the cytoplasm in pollen tubes. Finally, we describe several signaling components that regulate actin dynamics in pollen tubes.

Integrative analysis of differential circular RNA and long non-coding RNA profiles and associated competing endogenous RNA networks in esophageal squamous cell carcinoma.

Long non-coding RNAs (lncRNAs) and circular RNAs (circRNAs) play vital roles in the tumorigenesis of esophageal squamous cell carcinoma (ESCC). Nevertheless, the mechanism and regulatory network associated with this process remain largely unknown. In this study, we performed a comprehensive analysis of the expression of mRNAs, lncRNAs, and circRNAs by RNA-seq. A total of 3265 mRNAs, 1084 lncRNAs, and 38 circRNAs were found to be differentially expressed. Among these, 269 mRNAs were found to encode transcription factors (TFs). Functional enrichment analysis indicated that the dysregulated TFs are associated with the Hedgehog, Jak-STAT, TGF-beta, and MAPK signaling pathways. Furthermore, we constructed co-expression networks to screen the core lncRNAs and circRNAs involved in the regulation of transcription factors in these four pathways. Finally, we constructed a competing endogenous RNA (ceRNA) network of ESCC based on the abovementioned pathways. Our findings provide important insight into the role of lncRNAs and circRNAs in ESCC; the differentially expressed lncRNAs and circRNAs may represent potential targets for ESCC diagnosis and therapy.

Unusual characteristics of dicistrovirus-derived small RNAs in the small brown planthopper, Laodelphax striatellus.

In this study, sequences of small RNA (sRNA) libraries derived from the insect vector Laodelphax striatellus were assembled into contigs and used as queries for database searches. A large number of contigs were highly homologous to the genome sequence of an insect dicistrovirus, himetobi P virus (HiPV). Interestingly, HiPV-derived sRNAs had a wide size distribution, and were relatively abundant throughout the 18-30 nt size range with only a slight peak at 22 nt. HiPV sRNAs had a strong bias towards the sense strand, whilst the antisense sRNAs were predominantly 21 and 22 nt. HiPV sRNAs do not have the typical features of PIWI-interacting RNAs, but their 3' ends were preferentially cleaved at UA-rich sequences. Our data suggest that HiPV sRNAs may be derived both from activities of the RNA interference pathway and from cleavage of the viral genome by other host RNases.

A RhoGAP controls apical actin polymerization by inhibiting formin in Arabidopsis pollen tubes.

Formin is an important player in promoting apical actin polymerization in pollen tubes, but the mechanism regulating its activity remains unknown. We here identify REN1, a Rho GTPase-activating protein, as a negative regulator of formins in Arabidopsis pollen tubes. Specifically, we found that depletion of REN1 promotes apical actin polymerization and increases the amount of filamentous actin in pollen tubes. Interestingly, the effect of REN1 loss of function phenocopies the effect of formin gain of function, as it causes the formation of supernumerary membrane-derived actin bundles, which leads to tube swelling and membrane deformation. Importantly, inhibition of formins suppresses the phenotypic defects in ren1 mutant pollen tubes. We further demonstrate that REN1 physically interacts with the Arabidopsis formin protein AtFH5, predominantly with the C terminus, and inhibits the ability of AtFH5 to nucleate and assemble actin in vitro. Depletion of AtFH5 partially suppresses the phenotype in ren1 mutant pollen tubes, demonstrating that REN1 regulates apical actin polymerization at least partially through inhibiting AtFH5. We thus uncover a novel mechanism regulating formins and actin polymerization in plants.

Clinicopathologic features and surgical treatment prognosis of esophageal carcinosarcoma.

Background: Carcinosarcoma is a rare esophageal tumor, accounting for approximately 0.27-2.8% of malignant esophageal tumors. This study aims to investigate the clinical pathological characteristics, surgical treatment outcomes, and analysis of prognostic factors in esophageal carcinosarcoma (ECS). Methods: Clinical data from sixteen patients diagnosed with esophageal sarcomatoid carcinoma who underwent surgical interventions were retrospectively analyzed. Clinical and pathological features, treatment modalities, and postoperative outcomes were systematically examined. Results: Out of the 1261 patients who underwent surgical treatment for esophageal cancer, 16 cases were pathologically confirmed as carcinosarcoma. Among them, two underwent neoadjuvant chemotherapy, six received postoperative chemotherapy. Carcinosarcomas predominantly occurred in the middle (43.75%) and lower (50%) segments of the esophagus. Among the 16 cases, 10 presented as polypoid, 4 as ulcerative, and 2 as medullary types. Microscopic examination revealed coexistence and transitional transitions between sarcomatous and carcinoma components. Pathological staging showed 5 cases in stage T1, 2 in stage T2, and 9 in stage T3, with lymph node metastasis observed in 8 cases (50%). TNM staging revealed 2 cases in stage I, 9 in stage II, and 5 in stage III. The overall 1, 3, and 5-year survival rates were 86.67%, 62.5%, and 57.14%, respectively. Univariate analysis indicated that pathological N staging influenced survival rates, while multivariate analysis demonstrated that pathological N staging was an independent prognostic factor. Conclusions: Carcinosarcoma is a rare esophageal tumor, accounting for approximately 0.27-2.8% of malignant esophageal tumors. Histologically, the biphasic pattern is a crucial diagnostic feature, although the carcinomatous component may not always be evident, especially in limited biopsies, leading to potential misclassification as pure sarcoma or squamous cell carcinoma. Despite its large volume and cellular atypia, carcinosarcoma carries a favorable prognosis. Complete surgical resection of the tumor and regional lymph node dissection is the preferred treatment approach for esophageal carcinosarcoma.

Differential sensitivity of ADF isovariants to a pH gradient promotes pollen tube growth.

The actin cytoskeleton is one of the targets of the pH gradient in tip-growing cells, but how cytosolic pH regulates the actin cytoskeleton remains largely unknown. We here demonstrate that Arabidopsis ADF7 and ADF10 function optimally at different pH levels when disassembling actin filaments. This differential pH sensitivity allows ADF7 and ADF10 to respond to the cytosolic pH gradient to regulate actin dynamics in pollen tubes. ADF7 is an unusual actin-depolymerizing factor with a low optimum pH in in vitro actin depolymerization assays. ADF7 plays a dominant role in promoting actin turnover at the pollen tube apex. ADF10 has a typically high optimum pH in in vitro assays and plays a dominant role in regulating the turnover and organization of subapical actin filaments. Thus, functional specification and cooperation of ADF isovariants with different pH sensitivities enable the coordination of the actin cytoskeleton with the cytosolic pH gradient to support pollen tube growth.

Single-cell sequencing technology applied to epigenetics for the study of tumor heterogeneity.

BACKGROUND: Previous studies have traditionally attributed the initiation of cancer cells to genetic mutations, considering them as the fundamental drivers of carcinogenesis. However, recent research has shed light on the crucial role of epigenomic alterations in various cell types present within the tumor microenvironment, suggesting their potential contribution to tumor formation and progression. Despite these significant findings, the progress in understanding the epigenetic mechanisms regulating tumor heterogeneity has been impeded over the past few years due to the lack of appropriate technical tools and methodologies. RESULTS: The emergence of single-cell sequencing has enhanced our understanding of the epigenetic mechanisms governing tumor heterogeneity by revealing the distinct epigenetic layers of individual cells (chromatin accessibility, DNA/RNA methylation, histone modifications, nucleosome localization) and the diverse omics (transcriptomics, genomics, multi-omics) at the single-cell level. These technologies provide us with new insights into the molecular basis of intratumoral heterogeneity and help uncover key molecular events and driving mechanisms in tumor development. CONCLUSION: This paper provides a comprehensive review of the emerging analytical and experimental approaches of single-cell sequencing in various omics, focusing specifically on epigenomics. These approaches have the potential to capture and integrate multiple dimensions of individual cancer cells, thereby revealing tumor heterogeneity and epigenetic features. Additionally, this paper outlines the future trends of these technologies and their current technical limitations.

NAT10 Promotes Malignant Progression of Lung Cancer via the NF-κB Signaling Pathway.

BACKGROUND: NAT10 (N-acetyltransferase 10) is a newly identified novel acetyltransferase. Abnormal expression of NAT10 is associated with several human disorders, including cancer, autoimmune diseases, and cardiovascular disease. This study aimed to investigate the role of NAT10 in promoting lung cancer malignant progression through the NF-κB (nuclear factor κB) signaling pathway. METHODS: Cells lines BEAS-2B, NCI-H524, A549, PC-9, NCI-H23, and NCI-H258 were cultured for identification. Western blotting and PCR assays determined gene expression within the sample cells. Cellular functionality was assayed using CCK8 (Cell Counting Kit-8), Dual-Luciferase Reporter, and Colony formating. RESULTS: The PCR assay and Western blotting showed a significant elevation of NAT10 levels within tumor tissues compared to paraneoplastic tissues (p < 0.05). Specifically, NAT10 only affected the expression and content of RelA/p65 in lung cancer. Analysis from the TCGA (The Cancer Genome Atlas) database indicated that elevated expression levels of NAT10 in tumors can be a good prognostic indicator for lung cancer patients. The CCK8 assay showed that the knockdown of NAT10 significantly suppressed the A549 cells' progression rate (p < 0.05). The colony formation assays further confirmed that the overexpression of NAT10 significantly increased the generation of clones in the NCI-H524 cells (p < 0.05). The proliferation rate influenced by the overexpression of NAT10 was inhibited by blocking the NF-κB signaling pathway (p < 0.05). Dual-luciferase reporter gene assay results revealed NAT10's potential in promoting the NF-κB signaling pathway's activity in lung cancer. Immunohistochemical staining underscored a strong link between NAT10 protein expression and the NF-κB signaling pathway in lung cancer tissues. CONCLUSIONS: NAT10's expression is significantly upregulated in tumor tissues, supported by PCR results. NAT10 plays a role in the development and proliferation of lung cancer cells and can activate the NF-κB signaling pathway in lung cancer. Hence, NAT10's regulation of the NF-κB signaling pathway is critical in the malignant proliferation of lung cancer.

Myosin 1D and the branched actin network control the condensation of p62 bodies.

Biomolecular condensation driven by liquid-liquid phase separation (LLPS) is key to assembly of membraneless organelles in numerous crucial pathways. It is largely unknown how cellular structures or components spatiotemporally regulate LLPS and condensate formation. Here we reveal that cytoskeletal dynamics can control the condensation of p62 bodies comprising the autophagic adaptor p62/SQSTM1 and poly-ubiquitinated cargos. Branched actin networks are associated with p62 bodies and are required for their condensation. Myosin 1D, a branched actin-associated motor protein, drives coalescence of small nanoscale p62 bodies into large micron-scale condensates along the branched actin network. Impairment of actin cytoskeletal networks compromises the condensation of p62 bodies and retards substrate degradation by autophagy in both cellular models and Myosin 1D knockout mice. Coupling of LLPS scaffold to cytoskeleton systems may represent a general mechanism by which cells exert spatiotemporal control over phase condensation processes.

Cyclophilin B promotes cell proliferation, migration, invasion and angiogenesis via regulating the STAT3 pathway in non-small cell lung cancer.

Lung cancer is the most common type of cancer and has become the leading cause of cancer-associated mortality worldwide. It has been reported that expression of Cyclophilin B was greatly elevated in the pancreatic cancer patient sera as compared with the healthy volunteer sera. This study aimed to investigate the role and regulatory mechanism of CypB in NSCLC progression. The expression levels of CypB was detected in NSCLC samples and cell lines by ELISA, western blot and immunohistochemistry assay. In addition, CCK8, colony formation, scratch and transwell assays were used to evaluate the proliferation, migration and invasion of A549 cells with CypB silencing. The expression of angiogenesis related proteins and pathway-related factors were detected by western blot. In NSCLC samples, CypB expression was upregulated. The expression of CypB was significantly reduced in the siRNA-cyclophilin B group. In addition, CypB silencing inhibited cell proliferation, migration and invasion. The expression of angiogenesis related proteins and pathway-related factors have also changed significantly. These findings suggested that CypB silencing may suppress the proliferation, invasion, migration and angiogenesis of A549 cells via inhibiting STAT3 pathway.

Arabidopsis formin 2 regulates cell-to-cell trafficking by capping and stabilizing actin filaments at plasmodesmata.

Here, we demonstrate that Arabidopsis thaliana Formin 2 (AtFH2) localizes to plasmodesmata (PD) through its transmembrane domain and is required for normal intercellular trafficking. Although loss-of-function atfh2 mutants have no overt developmental defect, PD's permeability and sensitivity to virus infection are increased in atfh2 plants. Interestingly, AtFH2 functions in a partially redundant manner with its closest homolog AtFH1, which also contains a PD localization signal. Strikingly, targeting of Class I formins to PD was also confirmed in rice, suggesting that the involvement of Class I formins in regulating actin dynamics at PD may be evolutionarily conserved in plants. In vitro biochemical analysis showed that AtFH2 fails to nucleate actin assembly but caps and stabilizes actin filaments. We also demonstrate that the interaction between AtFH2 and actin filaments is crucial for its function in vivo. These data allow us to propose that AtFH2 regulates PD's permeability by anchoring actin filaments to PD.

A phloem-limited fijivirus induces the formation of neoplastic phloem tissues that house virus multiplication in the host plant.

A number of phloem-limited viruses induce the development of tumours (enations) in the veins of host plants, but the relevance of tumour induction to the life cycle of those viruses is unclear. In this study, we performed molecular and structural analyses of tumours induced by rice black-streaked dwarf virus (RBSDV, genus Fijivirus) infection in maize plants. The transcript level of the maize cdc2 gene, which regulates the cell cycle, was highly elevated in tumour tissues. Two-dimensional electrophoresis identified 25 cellular proteins with altered accumulation in the tumour tissues. These proteins are involved in various metabolic pathways, including photosynthesis, redox, energy pathways and amino acid synthesis. Histological analysis indicated that the tumours predominantly originated from hyperplastic growth of phloem, but those neoplastic tissues have irregular structures and cell arrangements. Immunodetection assays and electron microscopy observations indicated that in the shoots, RBSDV is confined to phloem and tumour regions and that virus multiplication actively occurs in the tumour tissue, as indicated by the high accumulation of non-structural proteins and formation of viroplasms in the tumour cells. Thus, the induction of tumours by RBSDV infection provides a larger environment that is favourable for virus propagation in the host plant.

The P2 of Wheat yellow mosaic virus rearranges the endoplasmic reticulum and recruits other viral proteins into replication-associated inclusion bodies.

Viruses commonly modify host endomembranes to facilitate biological processes in the viral life cycle. Infection by viruses belonging to the genus Bymovirus (family Potyviridae) has long been known to induce the formation of large membranous inclusion bodies in host cells, but their assembly and biological roles are still unclear. Immunoelectron microscopy of cells infected with the bymovirus Wheat yellow mosaic virus (WYMV) showed that P1, P2 and P3 are the major viral protein constituents of the membranous inclusions, whereas NIa-Pro (nuclear inclusion-a protease) and VPg (viral protein genome-linked) are probable minor components. P1, P2 and P3 associated with the endoplasmic reticulum (ER), but only P2 was able to rearrange ER and form large aggregate structures. Bioinformatic analyses and chemical experiments showed that P2 is an integral membrane protein and depends on the active secretory pathway to form aggregates of ER membranes. In planta and in vitro assays demonstrated that P2 interacts with P1, P3, NIa-Pro or VPg and recruits these proteins into the aggregates. In vivo RNA labelling using WYMV-infected wheat protoplasts showed that the synthesis of viral RNAs occurs in the P2-associated inclusions. Our results suggest that P2 plays a major role in the formation of membranous compartments that house the genomic replication of WYMV.

The CUG-initiated larger form coat protein of Chinese wheat mosaic virus binds to the cysteine-rich RNA silencing suppressor.

Some viruses use alternative translation initiation at non-AUG codons as a strategy to produce multiple proteins during gene expression. Here we show that, using this strategy, Chinese wheat mosaic virus (CWMV; Furovirus) expresses a larger form of coat protein (N-ext/CP) in infected plants. Site-directed mutagenesis and transient expression analysis confirmed that CWMV N-ext/CP is initiated at an upstream in-frame CUG codon at nucleotide position 207-209 of RNA 2, which adds a 39 amino acid (aa) N-terminal extension to the major CP. Interestingly, in planta and in vitro analyses indicated that CWMV N-ext/CP but not CP interacts with the CWMV cysteine-rich protein (CRP), an RNA silencing suppressor. We further determined that the N-terminal 39 aa extension, particularly the 10 aa region immediately upstream of the major CP coding region is responsible for the interaction of N-ext/CP with CRP. In an Agrobacterium co-infiltration assay, co-expression with N-ext/CP did not affect CRP silencing suppression activity. Thus the alternative translation initiation at a CUG codon provides the CWMV N-ext/CP with the ability to bind to the viral silencing suppressor.

Characterization of rice black-streaked dwarf virus- and rice stripe virus-derived siRNAs in singly and doubly infected insect vector Laodelphax striatellus.

Replication of RNA viruses in insect cells triggers an antiviral defense that is mediated by RNA interference (RNAi) which generates viral-derived small interfering RNAs (siRNAs). However, it is not known whether an antiviral RNAi response is also induced in insects by reoviruses, whose double-stranded RNA genome replication is thought to occur within core particles. Deep sequencing of small RNAs showed that when the small brown planthopper (Laodelphax striatellus) was infected by Rice black-streaked dwarf virus (RBSDV) (Reoviridae; Fijivirus), more viral-derived siRNAs accumulated than when the vector insect was infected by Rice stripe virus (RSV), a negative single-stranded RNA virus. RBSDV siRNAs were predominantly 21 and 22 nucleotides long and there were almost equal numbers of positive and negative sense. RBSDV siRNAs were frequently generated from hotspots in the 5'- and 3'-terminal regions of viral genome segments but these hotspots were not associated with any predicted RNA secondary structures. Under laboratory condition, L. striatellus can be infected simultaneously with RBSDV and RSV. Double infection enhanced the accumulation of particular genome segments but not viral coat protein of RBSDV and correlated with an increase in the abundance of siRNAs derived from RBSDV. The results of this study suggest that reovirus replication in its insect vector potentially induces an RNAi-mediated antiviral response.