Single-celled tubules represent a complicated structure that forms during development, requiring extension of a narrow cytoplasm surrounding a lumen exerting osmotic pressure that can burst the luminal membrane. Genetic studies on the excretory canal cell of Caenorhabditis elegans have revealed many proteins that regulate the cytoskeleton, vesicular transport, and physiology of the narrow canals. Here, we show that βH-spectrin regulates the placement of intermediate filament proteins forming a terminal web around the lumen, and that the terminal web in turn retains a highly conserved protein (EXC-9/CRIP1) that regulates apical endosomal trafficking. EXC-1/IRG, the binding partner of EXC-9, is also localized to the apical membrane and affects apical actin placement and RAB-8–mediated vesicular transport. The results suggest that an intermediate filament protein acts in a novel pathway to direct the traffic of vesicles to locations of lengthening apical surface during single-celled tubule development.

Formation and regulation of properly sized epithelial tubes is essential for multicellular life. The excretory canal cell of C. elegans provides a powerful model for investigating the integration of the cytoskeleton, intracellular transport, and organismal physiology to regulate the developmental processes of tube extension, lumen formation, and lumen diameter regulation in a narrow single cell. Multiple studies have provided new understanding of actin and intermediate filament cytoskeletal elements, vesicle transport, and the role of vacuolar ATPase in determining tube size. Most of the genes discovered have clear homologues in humans, with implications for understanding these processes in mammalian tissues such as Schwann cells, renal tubules, and brain vasculature. The results of several new genetic screens are described that provide a host of new targets for future studies in this informative structure.

The outbreak of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has led to the global coronavirus disease 2019 (COVID-19) pandemic, and the search for effective treatments has been limited. Furthermore, the rapid mutations of SARS-CoV-2 have posed challenges to existing vaccines and neutralizing antibodies, as they struggle to keep up with the increased viral transmissibility and immune evasion. However, there is hope in targeting the CD147-spike protein, which serves as an alternative point for the entry of SARS-CoV-2 into host cells. This protein has emerged as a promising therapeutic target for the development of drugs against COVID-19. Here, we demonstrate that the RNA-binding protein Human-antigen R (HuR) plays a crucial role in the post-transcriptional regulation of CD147 by directly binding to its 3′-untranslated region (UTR). We observed a decrease in CD147 levels across multiple cell lines upon HuR depletion. Furthermore, we identified that niclosamide can reduce CD147 by lowering the cytoplasmic translocation of HuR and reducing CD147 glycosylation. Moreover, our investigation revealed that SARS-CoV-2 infection induces an upregulation of CD147 in ACE2-expressing A549 cells, which can be effectively neutralized by niclosamide in a dose-dependent manner. Overall, our study unveils a novel regulatory mechanism of regulating CD147 through HuR and suggests niclosamide as a promising therapeutic option against COVID-19.

Background: Esophageal cancer (EC), especially esophageal squamous cell carcinoma, remained as one of the most aggressive tumors in China with a five-year survival rate of around 40%. Molecular characteristics through next-generation sequencing are becoming an emerging method in identifying prognostic biomarkers for better treatment management for EC patients. Methods: Targeted next-generation sequencing using a 422-gene pan-cancer panel was performed with tumor tissue samples from a total of 69 Asian non-surgical esophageal carcinoma patients (AEC) treated with chemoradiotherapy. A TCGA cohort of 143 EC patients and another Asian ESCC cohort of 47 patients were employed for validation. Results: In the AEC cohort, alterations in TP53 (94.2%) and NOTCH1 (55.1%) were the two most frequently observed alterations, whereas in the TCGA cohort, only TP53 alterations were observed at a high ratio (85.3%). Co-amplifications of FGF19 and CCND1 were found at a similar ratio in both cohorts. Multiple alterations in the DNA damage pathway were identified but not associated with overall survival in AEC. Using univariate and multivariate Cox regression analyses, six gene alterations including YAP1 amplification, RB1 alteration, BAP1 mutation, MYC amplification, WRN mutation, and BRIP1 mutation were identified as adverse prognostic factors in the AEC cohort. A Cox proportional hazard model based on the six prognosis-related genes was constructed and showed the ability in distinguishing EC patients with poorer disease outcomes in AEC and two validation cohorts. Conclusion: Six gene alterations were found to be potential unfavorable prognostic markers that might provide guidance in the treatment management for EC patients.

The evolutionarily conserved RNA-binding proteins HuR and MSI are essential for multiple developmental processes and are upregulated in many cancer tissues. The C. elegans homologues EXC-7 (HuR) and MSI-1 (MSI1 and MSI2) have been implicated in tubulogenesis, neural development, and specific behaviors that include male tail-curling to maintain contact with the hermaphrodite during mating. This behavior is mediated by serotonin signaling. Here, drug studies plus biochemical and genetic results indicate that MSI-1 affects serotonergic signaling through stabilization of mRNA of the Gα protein GOA-1/GNAO1 in neurons, which in turn affects activity of the serotonin synthase TPH-1/tryptophan hydroxylase via the response element CRH-1/CREB. EXC-7 (HuR) is also involved in this regulatory pathway. These results indicate a novel pathway and role for these RNA-binding proteins in regulating neurotransmitter levels that could be conserved in other tissues where these RNA-binding proteins are present. Impact Statement RNA-binding proteins Musashi and HuR upregulate serotonin levels for male-specific movement during mating via a novel pathway involving a neural Gα protein, response element, and serotonin synthase.

Ex vivo expansion of human hematopoietic stem cells (HSCs) holds promise for overcoming their limited availability, a major barrier to broader clinical application. Although recent advances in culture systems can increase HSC numbers, these conditions frequently impair self-renewal and induce myeloid bias, and the underlying molecular mechanisms remain poorly understood. Here, we performed single-cell multiome sequencing (scMultiome-seq) on human umbilical cord blood-derived CD34⁺ hematopoietic stem and progenitor cells to co-profile transcriptional and epigenetic adaptations within the same cells during ex vivo culture. Our analyses revealed reduced transcriptional and epigenetic HSC signatures, accompanied by markedly increased activity of myeloid-associated transcription factor motifs, providing molecular insight into the functional decline and myeloid bias of cultured HSCs. We further observed substantial functional heterogeneity among phenotypically defined HSCs following culture. To address these limitations, we established a niche-mimetic culture system that integrates intrinsic and extrinsic bone marrow regulatory cues, including pharmacologic inhibition of the m6A reader YTHDF2 using the small molecule Y13-27, a three-dimensional microenvironment, and N-cadherin-mediated adhesion. This condition (3D-NcadP-Y) robustly preserved long-term repopulating capacity. When combined with the self-renewal agonist UM729, the resulting platform (3D-NcadP-Y-UM) uniquely enabled the expansion of serially transplantable long-term HSCs with balanced multilineage potential. scMultiome-seq and cellular analyses demonstrated that this condition preserves transcriptional and epigenetic long-term HSC signatures, maintains multilineage-associated transcription factor motifs, and limits excessive cell-cycle activation. Together, these findings elucidate molecular mechanisms underlying culture-induced HSC dysfunction and establish a niche-mimetic strategy for expanding functional human long-term HSCs while preserving key features of stemness.