FOXD3 controls pluripotency through modulating enhancer activity

FAM3A maintains metabolic homeostasis by interacting with F1-ATP synthase to regulate the activity and assembly of ATP synthase

Reduced mitochondrial ATP synthase (ATPS) capacity plays crucial roles in the pathogenesis of metabolic disorders. However, there is currently no effective strategy for synchronously stimulating the expressions of ATPS key subunits to restore its assembly. This study determined the roles of mitochondrial protein FAM3A in regulating the activity and assembly of ATPS in hepatocytes. FAM3A is localized in mitochondrial matrix, where it interacts with F1-ATPS to initially activate ATP synthesis and release, and released ATP further activates P2 receptor-Akt-CREB pathway to induce FOXD3 expression. FOXD3 synchronously stimulates the transcriptions of ATPS key subunits and assembly genes to increase its assembly and capacity, augmenting ATP synthesis and inhibiting ROS production. FAM3A, FOXD3 and ATPS expressions were reduced in livers of diabetic mice and NAFLD patients. FOXD3 expression, ATPS capacity and ATP content were reduced in various tissues of FAM3A-deficient mice with dysregulated glucose and lipid metabolism. Hepatic FOXD3 activation increased ATPS assembly to ameliorate dysregulated glucose and lipid metabolism in obese mice. Hepatic FOXD3 inhibition or knockout reduced ATPS capacity to aggravate HFD-induced hyperglycemia and steatosis. In conclusion, FAM3A is an active ATPS component, and regulates its activity and assembly by activating FOXD3. Activating FAM3A-FOXD3 axis represents a viable strategy for restoring ATPS assembly to treat metabolic disorders.

Activation of Tyrosine Metabolism in CD13+ Cancer Stem Cells Drives Relapse in Hepatocellular Carcinoma

Purpose

Cancer stem cells (CSCs) are naturally resistant to chemotherapy, explaining why tumor relapse frequently occurs after initial regression upon administration of chemotherapeutic agents in most cases. A CSC population characterized by CD13 expression has been identified in hepatocellular carcinoma (HCC). In the current study, we aimed to clarify the molecular mechanism by which it escapes conventional therapies.

Materials and Methods

Here, we used flow cytometry to examine the percentage of CD13⁺ CSCs in HepG2 and HuH7 cells after chemotherapy. Using in vitro isotope labeling technique, we compared metabolic pathways between CD13⁺ and CD13^- subpopulations. Using co-immunoprecipitation and western blotting, we determined the target expressions in protein levels under different conditions. We also performed immunohistochemistry to detect the target proteins under different conditions. Animal models were constructed to verify the potential role of tyrosine metabolism in post-chemotherapeutic relapse in vivo.

Results

We observed that quiescent CD13⁺ CSCs are enriched after chemotherapy in HCCs, and serve as a reservoir for recurrence. Mechanistically, CD13⁺ CSCs were dependent on aerobic metabolism of tyrosine rather than glucose as energy source. Tyrosine metabolism also generated nuclear acetyl-CoA to acetylate and stabilize Foxd3, thereby allowing CD13⁺ CSCs cells to sustain quiescence and resistance to chemotherapeutic agents.

Conclusion

These findings encourage further exploration of eliminating CD13⁺ cells by targeting specific metabolic pathways to prevent recurrence in HCCs.

miR‑425‑5p promotes cell proliferation, migration and invasion by directly targeting FOXD3 in hepatocellular carcinoma cells

MicroRNAs (miRs) are important regulators of the tumorigenesis and metastasis of various cancers. In the present study, the roles and underlying mechanisms of miR‑425‑5p in the development of hepatocellular carcinoma (HCC) were investigated. RT‑qPCR analysis revealed that miR‑425‑5p was upregulated in HCC tissues and cell lines. A functional study in vitro using MTT assays, colony formation and Transwell assays demonstrated that overexpression of miR‑425‑5p promoted the proliferation, migration, and invasion of HCC cells, prevented cell apoptosis and accelerates the epithelial‑mesenchymal transition process, whereas miR‑425‑5p knockdown induced opposing effects. A further mechanistic study revealed that forkhead box D3 (FOXD3) was a direct target of miR‑425‑5p, and gain‑ and loss‑of‑function of FOXD3 studies demonstrated that FOXD3 suppressed HCC cell proliferation, migration, and invasion. Furthermore, rescue experiments revealed that overexpression of FOXD3 counteracted the positive effects of miR‑425‑5p on HCC malignant behaviors. Collectively, the present results demonstrated that miR‑425‑5p promoted HCC cell proliferation, migration, and invasion by suppressing FOXD3 expression, potentially providing a novel target for the treatment of HCC.

From Pioneer to Repressor: Bimodal foxd3 Activity Dynamically Remodels Neural Crest Regulatory Landscape In Vivo

The neural crest (NC) is a transient embryonic stem cell-like population characterized by its multipotency and broad developmental potential. Here, we perform NC-specific transcriptional and epigenomic profiling of foxd3-mutant cells in vivo to define the gene regulatory circuits controlling NC specification. Together with global binding analysis obtained by foxd3 biotin-ChIP and single cell profiles of foxd3-expressing premigratory NC, our analysis shows that, during early steps of NC formation, foxd3 acts globally as a pioneer factor to prime the onset of genes regulating NC specification and migration by re-arranging the chromatin landscape, opening cis-regulatory elements and reshuffling nucleosomes. Strikingly, foxd3 then gradually switches from an activator to its well-described role as a transcriptional repressor and potentially uses differential partners for each role. Taken together, these results demonstrate that foxd3 acts bimodally in the neural crest as a switch from “permissive” to “repressive” nucleosome and chromatin organization to maintain multipotency and define cell fates.

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FoxD3 primes neural crest specification by modulating distal enhancers

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FoxD3 represses a number of neural crest migration and differentiation genes

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In neural crest, FoxD3 acts to switch chromatin from “permissive” to “repressive”

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Distinctive gene regulatory mechanisms underlie the bimodal action of FoxD3