A DLG1-ARHGAP31-CDC42 axis is essential for the intestinal stem cell response to fluctuating niche Wnt signaling

MTHFD2: A metabolic checkpoint altering trophoblast invasion and migration by remodeling folate-nucleotide metabolism in recurrent spontaneous abortion

Recurrent spontaneous abortion (RSA) affects female reproduction worldwide, yet its pathological mechanisms are still unclear. It has been reported that cellular metabolism reprogramming is a critical step for trophoblasts during embryo implantation. Herein, MTHFD2 was recognized as a key metabolic checkpoint attributed to RSA occurrence. This work figured out that the expression level of MTHFD2 was significantly inhibited in villus tissues from RSA patients, suggesting the potential role of MTHFD2 in RSA occurrence. Moreover, MTHFD2 knockdown impaired cellular folate-nucleotide metabolism, induced the accumulation of AICAR, and thereby impairing the EMT process to inhibit the invasion and migration of trophoblasts Besides, the AICAR accumulation further activated the downstream AMPK which deactivated the JAK/STAT/Slug pathway and ultimately deactivated the EMT process. Using a mouse model, MTHFD2 inhibition was observed to induce embryo implantation failure in vivo. Our results highlighted MTHFD2 as a metabolic checkpoint that remodeled folate-nucleotide metabolism to regulate the EMT process and ultimately altered the migration and invasion of trophoblasts in RSA occurrence. Our findings suggested that MTHFD2 was a promising therapeutic target in recurrent spontaneous abortion treatment.

CDC42 Regulatory Patterns Related To Inflammatory Bowel Disease and Hyperglycemia

As a member of the rat sarcoma virus homolog (Rho) guanosine triphosphatases (GTPases) family, Cdc42 represents a "switch" molecule, by changing from inactive (GDP-associated) to active form (GTP-associated) and vice versa. Cdc42 is activated by the guanine nucleotide exchange factors (GEFs), in contrast to GTPase-activating proteins (GAPs) which are responsable for formation of GDP-binding, inactive form of Cdc42. Some of the fundamental cellular functions are regulated by Cdc42 such as cytosceleton dynamics, cell cycling, transcription and cellular trafficking. In the gastrointestinal system, Cdc42 participates in maintenance of the functional epithelial barrier by controling intestinal epithelial cell polarity and interconnections. In addition, Cdc42 expression in pancreatic β-cells is of great importance for glucose-stimulated insulin secretion. From the pathophysiological point of view, literature data provide some evidence for Cdc42 sigaling in inflammatory bowel disease, as well as in hyperglycemic conditions related to diabetes mellitus. However, whether and by which mechanism Cdc42 contributes to the IBD patophysiology in hyperglycemic conditions is still not fully understood. Therefore, we performed bioinformatics analysis to predict transcriptional factor-gene interactions related to Cdc42 signaling in inflammatory bowel disease in hyperglycemic conditions. In silico analysis predicts various interactions between input genes and output transcriptional factors, and therefore reveals the molecules with the highest predicted effect on particular genes. Based on the predictive interactions with the intracellular molecules, carefully designed in vitro or in vivo studies are required to get better insight in the pathways of interest. Better understanding of Cdc42 molecular pathway in inflammatory bowel disease and hyperglycemia will help identifying potential targets for therapeutical modifications in clinical setting resulting in better control of the disease progression.

BMP suppresses Wnt signaling via the Bcl11b-regulated NuRD complex to maintain intestinal stem cells

Lgr5+ intestinal stem cells (ISCs) are crucial for the intestinal epithelium renewal and regeneration after injury. However, the mechanism underlying the interplay between Wnt and BMP signaling in this process is not fully understood. Here we report that Bcl11b, which is downregulated by BMP signaling, enhances Wnt signaling to maintain Lgr5+ ISCs and thus promotes the regeneration of the intestinal epithelium upon injury. Loss of Bcl11b function leads to a significant decrease of Lgr5+ ISCs in both intestinal crypts and cultured organoids. Mechanistically, BMP suppresses the expression of Bcl11b, which can positively regulate Wnt target genes by inhibiting the function of the Nucleosome Remodeling and Deacetylase (NuRD) complex and facilitating the β-catenin-TCF4 interaction. Bcl11b can also promote intestinal epithelium repair after injuries elicited by both irradiation and DSS-induced inflammation. Furthermore, Bcl11b deletion prevents proliferation and tumorigenesis of colorectal cancer cells. Together, our findings suggest that BMP suppresses Wnt signaling via Bcl11b regulation, thus balancing homeostasis and regeneration in the intestinal epithelium.

Cdc42 improve SARS-CoV-2 spike protein-induced cellular senescence through activating of Wnt/β-Catenin signaling pathway

Introduction

SARS-CoV-2 infection drove senescent cells and the senescence-associated phenotypes were reported playing roles in disease progression, which contributes to severe COVID-19 and related sequelae. Cdc42 is involved in the regulation of cellular senescence. This study, aimed to investigate the mechanism of the SARS-CoV-2 spike protein regulating cellular senescence through Cdc42.

Methods

K18-hACE2 mice were infected with SARS-CoV-2 Omicron BA.4 or stimulated with spike protein through the airway, the senescent cells and Cdc42 expression in lung tissue were detected. Overexpression of spike protein or exogenous incubation of spike protein was used to simulate the induction of cellular senescence by spike protein. Mechanistic insights into the role of Cdc42 were mainly explored using Western Blot and qRT-PCR.

Results

Spike protein, SARS-CoV-2 infection related, accelerates cell aging by upregulating Cdc42 expression, which furtherly activated the Wnt/β-catenin signaling pathway. Conversely, treatment with ML141 in animal models, a Cdc42 inhibitor, reduced cellular senescence and ameliorated lung injury and inflammation. These results suggest that the upregulation of Cdc42 by the SARS-CoV-2 spike protein induces cellular senescence and enhances β-catenin nuclear translocation.

Discussion

This study provides insights into the mechanisms underlying cellular senescence induced by the SARS-CoV-2 spike protein, offering potential strategies to mitigate the inflammatory response and complications associated with COVID-19 in both the acute and long-term phases.

Immunoregulation and male reproductive function: Impacts and mechanistic insights into inflammation

This paper investigates the complex relationship between the immune system and male reproductive processes, emphasizing how chronic inflammation can adversely affect male reproductive health. The immune system plays a dual role; it protects and regulates reproductive organs and spermatogenesis while maintaining reproductive health through immune privilege in the testes and the activities of various immune cells and cytokines. However, when chronic inflammation persists or intensifies, it can disrupt this balance, leading to immune attacks on reproductive tissues and resulting in infertility.This study provides a detailed analysis of how chronic inflammation can impair sperm production, sperm quality, and the secretion of gonadal hormones both directly and indirectly. It also delves into the critical roles of testicular immune privilege, various immune cells, and cytokines in sustaining reproductive health and examines the impacts of infections, autoimmune diseases, and environmental factors on male fertility.

Increased activity of epithelial Cdc42 Rho GTPase and tight junction permeability in the Cftr knockout intestine

Increased intestinal permeability is a manifestation of cystic fibrosis (CF) in people with CF (pwCF) and in CF mouse models. CF transmembrane conductance regulator knockout (Cftr KO) mouse intestine exhibits increased proliferation and Wnt/β-catenin signaling relative to wild-type mice (WT). Since the Rho GTPase Cdc42 plays a central role in intestinal epithelial proliferation and tight junction remodeling, we hypothesized that Cdc42 may be altered in the Cftr KO crypts. Immunofluorescence showed distinct tight junction localization of Cdc42 in Cftr KO fresh crypts and enteroids, the latter indicating an epithelial-autonomous feature. Quantitative PCR and immunoblots revealed similar expression of Cdc42 in the Cftr KO crypts/enteroids relative to WT, whereas pulldown assays showed increased GTP-bound (active) Cdc42 in proportion to total Cdc42 in Cftr KO enteroids. Cdc42 activity in the Cftr KO and WT enteroids could be reduced by inhibition of the Wnt transducer Disheveled. With the use of a dye permeability assay, Cftr KO enteroids exhibited increased paracellular permeability to 3 kDa dextran relative to WT. Leak permeability and Cdc42 tight junction localization were reduced to a greater extent by inhibition of Wnt/β-catenin signaling with endo-IWR1 in Cftr KO relative to WT enteroids. Increased proliferation or inhibition of Cdc42 activity with ML141 in WT enteroids had no effect on permeability. In contrast, inhibition of Cdc42 with ML141 increased permeability to both 3 kDa dextran and tight junction impermeant 500 kDa dextran in Cftr KO enteroids. These data suggest that increased constitutive Cdc42 activity may alter the stability of paracellular permeability in Cftr KO crypt epithelium.NEW & NOTEWORTHY Increased tight junction localization and GTP-bound activity of the Rho GTPase Cdc42 was identified in small intestinal crypts and enteroids of cystic fibrosis (CF) transmembrane conductance regulator knockout (Cftr KO) mice. The increase in epithelial Cdc42 activity was associated with increased Wnt signaling. Paracellular flux of an uncharged solute (3 kDa dextran) in Cftr KO enteroids indicated a moderate leak permeability under basal conditions that was strongly exacerbated by Cdc42 inhibition. These findings suggest increased activity of Cdc42 in the Cftr KO intestine underlies alterations in intestinal permeability.

Activation of fetal-like molecular programs during regeneration in the intestine and beyond

Tissue regeneration after damage is generally thought to involve the mobilization of adult stem cells that divide and differentiate into progressively specialized progeny. However, recent studies indicate that tissue regeneration can be accompanied by reversion to a fetal-like state. During this process, cells at the injury site reactivate programs that operate during fetal development but are typically absent in adult homeostasis. Here, we summarize our current understanding of the molecular signals and epigenetic mediators that orchestrate "fetal-like reversion" during intestinal regeneration. We also explore evidence for this phenomenon in other organs and species and highlight open questions that merit future examination.

A growth factor-reduced culture system for colorectal cancer organoids

Although organoids derived from tumor tissues have been widely used in cancer research, it is a great challenge for cultured organoids to retain the characteristics of the original tumor tissues due to their heterogeneity. In this study, we explore organoid culture recipes to capture tumor features of colorectal cancers. We find that the activation of Wnt and EGF signaling and inhibition of BMP signaling are non-essential for the survival of most colorectal cancer organoids (CRCOs). We design a growth factor-reduced culture medium containing FGF10, A83-01 (TGF-β type I receptor inhibitor), SB202190 (p38 MAPK inhibitor), gastrin, and nicotinamide. Using this medium, we can maintain tumor features in long-term CRCO cultivation, as evidenced by histopathology, genetic stability, tumorigenicity, and response of clinical treatments. Our findings offer a reliable and economical strategy for CRCO culture, facilitating the utilization of organoids in colorectal cancer research and treatment.

Composition, Diversity and Sex-Related Differences in Intestinal Microbiota in Captive African Penguins (Spheniscus demersus)

An understanding of the microbial communities in African penguins (Spheniscus demersus) could provide valuable information for saving this endangered species. The objective of this study was to investigate the composition, diversity and sex-related differences in the intestinal microbiota of captive African penguins. Fecal samples were collected from 21 captive adult African penguins reared in the same conditions at Shanghai Zoo. The results show that Proteobacteria, Actinobacteria and Firmicutes were the predominant bacteria in the intestinal microbiota of the captive African penguins. No difference was found in microbial diversity between female and male African penguins, as shown by their similar alpha and beta diversities. However, a notable sex-related difference was found between their microbial compositions. Female African penguins have a higher abundance of Pseudomonas and a lower abundance of Kocuria than males. A functional prediction indicates that the "mRNA surveillance pathway", "Polyketide sugar unit biosynthesis", "Wnt signaling pathway", "Lysosome" and "Cell cycle" pathways were significantly enriched in the microbiota of female African penguins. In conclusion, the present study indicates that the compositions and predicted functions of the intestinal microbiota are significantly different between the sexes. Our data suggest that the intestinal microbiota of female African penguins are more unstable than the intestinal microbiota of males in captivity.

Loss of TTC17 promotes breast cancer metastasis through RAP1/CDC42 signaling and sensitizes it to rapamycin and paclitaxel

BACKGROUND

Breast cancer (BC) metastasis is the leading cause of poor prognosis and therapeutic failure. However, the mechanisms underlying cancer metastasis are far from clear.

METHODS

We screened candidate genes related to metastasis through genome-wide CRISPR screening and high-throughput sequencing of patients with metastatic BC, followed by a panel of metastatic model assays. The effects of tetratricopeptide repeat domain 17 (TTC17) on migration, invasion, and colony formation ability together with the responses to anticancer drugs were investigated in vitro and in vivo. The mechanism mediated by TTC17 was determined by RNA sequencing, Western blotting, immunohistochemistry, and immunofluorescence. The clinical significance of TTC17 was evaluated using BC tissue samples combined with clinicopathological data.

RESULTS

We identified the loss of TTC17 as a metastasis driver in BC, and its expression was negatively correlated with malignancy and positively correlated with patient prognosis. TTC17 loss in BC cells promoted their migration, invasion, and colony formation capacity in vitro and lung metastasis in vivo. Conversely, overexpressing TTC17 suppressed these aggressive phenotypes. Mechanistically, TTC17 knockdown in BC cells resulted in the activation of the RAP1/CDC42 pathway along with a disordered cytoskeleton in BC cells, and pharmacological blockade of CDC42 abolished the potentiation of motility and invasiveness caused by TTC17 silencing. Research on BC specimens demonstrated reduced TTC17 and increased CDC42 in metastatic tumors and lymph nodes, and low TTC17 expression was linked to more aggressive clinicopathologic characteristics. Through screening the anticancer drug library, the CDC42 inhibitor rapamycin and the microtubule-stabilizing drug paclitaxel showed stronger inhibition of TTC17-silenced BC cells, which was confirmed by more favorable efficacy in BC patients and tumor-bearing mice receiving rapamycin or paclitaxel in the TTC17^Low arm.

CONCLUSIONS

TTC17 loss is a novel factor promoting BC metastasis, that enhances migration and invasion by activating RAP1/CDC42 signaling and sensitizes BC to rapamycin and paclitaxel, which may improve stratified treatment strategies under the concept of molecular phenotyping-based precision therapy of BC.