AP1c and SOC1 Form a Regulatory Feedback Loop to Regulate Flowering Time in Soybean.

Flowering time is a key agronomic trait that directly affects soybean yield. Both APETALA1 (AP1) and SUPPRESSOR OF OVEREXPRESSION OF CO 1 (SOC1) regulate flowering time in soybean, but their genetic and regulatory relationships have not been clarified. Here, we report that AP1c physically interacted with two SOC1 proteins, SOC1a and SOC1b, and that these SOC1s upregulated the expression of AP1c, promoting flowering. Moreover, AP1c repressed the expression of the SOC1s by directly binding to their promoters, thus preventing plants from flowering too early. These findings indicate that AP1c and SOC1s form a regulatory feedback loop that regulates flowering time. Importantly, we identified an exceptional allele, AP1cG, that was selected for during soybean domestication and promotes the early-flowering phenotype in cultivated soybean. Collectively, our work identifies a previously unknown allelic combination potentially useful for both classical and molecular soybean breeding.

Ehbp1 orchestrates orderly sorting of Wnt/Wingless to the basolateral and apical cell membranes.

Wingless (Wg)/Wnt signaling plays a critical role in both development and adult tissue homeostasis. In the Drosophila larval wing disc epithelium, the orderly delivery of Wg/Wnt to the apical and basal cell surfaces is essential for wing development. Here, we identified Ehbp1 as the switch that dictates the direction of Wg/Wnt polarized intracellular transport: the Adaptor Protein complex 1 (AP-1) delivers Wg/Wnt to the basolateral cell surface, and its sequestration by Ehbp1 redirects Wg/Wnt for apical delivery. Genetic analyses showed that Ehbp1 specifically regulates the polarized distribution of Wg/Wnt, a process that depends on the dedicated Wg/Wnt cargo receptor Wntless. Mechanistically, Ehbp1 competes with Wntless for AP-1 binding, thereby preventing the unregulated basolateral Wg/Wnt transport. Reducing Ehbp1 expression, or removing the coiled-coil motifs within its bMERB domain, leads to basolateral Wg/Wnt accumulation. Importantly, the regulation of polarized Wnt delivery by EHBP1 is conserved in vertebrates. The generality of this switch mechanism for regulating intracellular transport remains to be determined in future studies.

Deciphering the influence of AP1M2 in modulating hepatocellular carcinoma growth and Mobility through JNK/ErK signaling pathway control.

BACKGROUND: Hepatocellular Carcinoma (HCC) is the most common digestive system malignancy, with unclear pathogenesis and low survival rates. AP1M2 is associated with tumor progression, but its role and molecular mechanisms in HCC remain poorly understood and require further investigation. METHODS: We utilized the Gene Expression Omnibus (GEO) and Expression Analysis Interactive Hub (XENA) databases to assess AP1M2 mRNA expression levels in HCC patients. Additionally, we employed the Cancer Genome Atlas (TCGA) database to identify pathways associated with both AP1M2 and HCC development. To evaluate the effect of AP1M2 on HCC cell proliferation and migration, we employed various techniques including EdU, CCK-8, Colony formation assay, and Transwell assays. Furthermore, Western blot analysis was conducted to examine the signaling pathways influenced by AP1M2. RESULTS: AP1M2 expression was significantly increased at the mRNA level in HCC tissues(P<0.001). Importantly, overall survival (OS) analysis confirmed the association between higher AP1M2 expression and a poorer prognosis in HCC patients compared to those with lower AP1M2 expression (P<0.019).Multivariate Cox regression analysis showed that AP1M2 was an independent prognostic factor and a valid predictor for HCC patients. Furthermore, GSEA results indicated differential enrichment of lipid, metal metabolism, and coagulation processes in HCC samples demonstrating a high AP1M2 expression phenotype. In vitro experiments supported these findings by demonstrating that AP1M2 promotes HCC cell proliferation and migration, while activating the JNK/ERK pathway. CONCLUSION: Our findings indicate that AP1M2 expression may serve as a potential molecular marker indicating a poor prognosis for HCC patients. Furthermore, we have demonstrated that AP1M2 significantly influences HCC cell proliferation and migration, with the JNK/ERK signaling pathway playing a key role in AP1M2-mediated regulation in the context of HCC.

Transcriptional upregulation of MMP-9 gene under hyperglycemic conditions in AGS cells: Role of AP-1 transcription factor.

Gastric cancer and diabetes are two complex and interrelated diseases having significant impact on global health. Hyperglycemic condition notably exacerbates cancer by promoting inflammation, angiogenesis, and metastasis. Elevated glucose levels can also upregulate the expression of specific matrix metalloproteinases (MMPs), especially MMP-9, which is associated with cancer cell migration and invasion. However, the molecular mechanism behind such upregulation remains unexplored. In the present study, we have identified the mechanism for hyperglycemia-induced transcriptional activation of MMP-9, in gastric adenocarcinoma (AGS) cells. Using various tools like luciferase-reporter assays with promoter deletion constructs, siRNAs, pharmacological inhibitors, and nuclear translocation experiments, we have identified that the transcriptional activation of MMP-9 under hyperglycemic conditions is predominantly governed by the MAPK pathway, via formation of the AP-1 heterodimer. The p65 NF-κB signaling pathway, although activated, plays no significant role in regulating hyperglycemia-induced MMP-9 expression. Chromatin immunoprecipitation studies indicate that the distal AP-1 binding site is responsible for hyperglycemia-induced MMP-9 transcription; whereas the proximal one accounts for both hyperglycemia-induced and basal MMP-9 transcription. Therefore, binding of AP-1 at both the proximal and distal binding sites on the MMP-9 promoter region is required for hyperglycemia-induced MMP-9 expression. Overall, our study unveils a novel mechanism of MMP-9 transcription under hyperglycemic conditions and also suggests that inhibiting the binding of the AP-1 heterodimer with its distal binding site can potentially reduce the complications developed during gastric cancer-hyperglycemia co-morbidity. A drug designed specifically to inhibit this interaction may prevent hyperglycemia-induced tumor aggressiveness to a considerable extent by impeding MMP-9 transcription.

The Oncoprotein Fra-2 Drives the Activation of Human Endogenous Retrovirus Env Expression in Adult T-Cell Leukemia/Lymphoma (ATLL) Patients.

Human endogenous retroviruses (HERVs) are retroviral sequences integrated into 8% of the human genome resulting from ancient exogenous retroviral infections. Unlike endogenous retroviruses of other mammalian species, HERVs are mostly replication and retro-transposition defective, and their transcription is strictly regulated by epigenetic mechanisms in normal cells. A significant addition to the growing body of research reveals that HERVs' aberrant activation is often associated with offsetting diseases like autoimmunity, neurodegenerative diseases, cancers, and chemoresistance. Adult T-cell leukemia/lymphoma (ATLL) is a very aggressive and chemoresistant leukemia caused by the human T-cell leukemia virus type 1 (HTLV-1). The prognosis of ATLL remains poor despite several new agents being approved in the last few years. In the present study, we compare the expression of HERV genes in CD8+-depleted PBMCs from HTLV-1 asymptomatic carriers and patients with acute ATLL. Herein, we show that HERVs are highly upregulated in acute ATLL. Our results further demonstrate that the oncoprotein Fra-2 binds the LTR region and activates the transcription of several HERV families, including HERV-H and HERV-K families. This raises the exciting possibility that upregulated HERV expression could be a key factor in ATLL development and the observed chemoresistance, potentially leading to new therapeutic strategies and significantly impacting the field of oncology and virology.

The transcription factors NR5A1 and JUNB cooperate to activate the Axl promoter in mouse Sertoli cell lines.

BACKGROUND: The Axl gene is a receptor tyrosine kinase essential for male fertility. With other Tyro3 family members, it regulates cell apoptosis and preserves the organization of seminiferous tubules. However, the regulation of the expression of Axl in testicular Sertoli cells is not entirely understood. The transcription factors NR5A1 and JUNB are involved in several male fertility mechanisms such as sex development and steroidogenesis. We hypothesize that Axl promoter activity is regulated by cooperation between JUNB and NR5A1 in Sertoli cells. METHODS AND RESULTS: Following transfections of TM4 Sertoli cells with DsiRNA interference against Axl, our results show that cell morphology may be regulated by AXL. Using transfections of expression plasmids and reporter plasmids containing the Axl promoter, we report that Axl expression is highly activated by cooperation between NR5A1 and JUNB in TM4 and 15P-1 Sertoli cells. Chromatin immunoprecipitation and luciferase reporter assays with 5' promoter deletions demonstrate that JUNB and NR5A1 are being recruited to DNA regulatory elements in the proximal region of the Axl promoter. The fourth intronic region of Axl also participates in the recruitment of JUNB. CONCLUSION: Thus, Axl expression is regulated by a cooperation between the transcription factors JUNB and NR5A1 and influences the morphology of TM4 Sertoli cells.

SHP2-Triggered Endothelial Cell Activation Fuels Estradiol-Independent Endometrial Sterile Inflammation.

Sterile inflammation occurs in various chronic diseases due to many nonmicrobe factors. Examples include endometrial hyperplasia (EH), endometriosis, endometrial cancer, and breast cancer, which are all sterile inflammation diseases induced by estrogen imbalances. However, how estrogen-induced sterile inflammation regulates EH remains unclear. Here, a single-cell RNA-Seq is used to show that SHP2 upregulation in endometrial endothelial cells promotes their inflammatory activation and subsequent transendothelial macrophage migration. Independent of the initial estrogen stimulation, IL1ß and TNFα from macrophages then create a feedforward loop that enhances endothelial cell activation and IGF1 secretion. This endothelial cell-macrophage interaction sustains sterile endometrial inflammation and facilitates epithelial cell proliferation, even after estradiol withdrawal. The bulk RNA-Seq results and phosphoproteomic analysis show that endothelial SHP2 mechanistically enhances RIPK1 activity by dephosphorylating RIPK1Tyr380. This event activates downstream activator protein 1 (AP-1) and instigates the inflammation response. Furthermore, targeting SHP2 using SHP099 (an allosteric inhibitor) or endothelial-specific SHP2 deletion alleviates endothelial cell activation, macrophage infiltration, and EH progression in mice. Collectively, the findings demonstrate that SHP2 mediates the transition of endothelial activation from estradiol-driven acute inflammation to macrophage-amplified chronic inflammation. Targeting sterile inflammation mediated by endothelial cell activation is a promising strategy for nonhormonal intervention in estrogen-related diseases.

Knocking down RAD51AP1 enhances chemosensitivity by inhibiting the self-renewal of CD133 positive ovarian cancer stem-like cells.

PURPOSE: This study was designed to investigate the function of RAD51AP1 in the self-renewal and chemosensitivity of CD133 positive (CD133+) ovarian cancer (OC) stem-like cells. METHODS: CD133+ (CD133 positive) OVCAR4 and CD133 negative (CD133-) OVCAR4 cells were separated from OVCAR4 by flow cytometry. Then, the separated CD133+OVCAR4 cells were divided into the following groups: Vector group; RAD51AP1 group; siNC group; si-RAD51AP1 group. Next, sphere-formation assay and colony forming assay were used to evaluate the self-renewal and proliferation ability of cells; western blot to detect the expression of RAD51AP1, transforming growth factor beta 1 (TGF-ß1) and SMAD4 proteins in tissues and cells; qRT-PCR to assess the mRNA levels of sex-determining region Y-box 2 (SOX2), octamer-binding transcription factor 4 (OCT4), NANOG and Kruppel-like factor 4 (KLF4). RESULTS: The performance of CD133+OVCAR4 cells was much better than that of CD133-OVCAR4 cells in sphere-formation assay and colony forming assay. Besides, compared with adjacent group and CD133-OVCAR4 cells, the expression level of RAD51AP1 increased significantly in OC group and CD133+OVCAR4 cells. Moreover, the over-expression of RAD51AP1 promoted the self-renewal and proliferation of CD133+OVCAR4 cells. On the contrary, knocking down the expression level of RAD51AP1 could inhibit the self-renewal and proliferation of CD133+OVCAR4 cells and improve the sensitivity of cells to chemotherapy drugs. CONCLUSION: The findings of this study showed that RAD51AP1 was highly expressed in OC tissue and CD133+OVCAR4 cells, and regulated the self-renewal and chemosensitivity of tumor cells through the TGF-ß1/SMAD4 signaling pathway.

SARS-CoV-2 NSP14 induces AP-1 transcriptional activity via its interaction with MEK.

The NSP14 protein of SARS-CoV-2 not only facilitates viral replication but also plays a pivotal role in activating the host immune system by enhancing cytokine production. In this study, we found that NSP14 markedly activated the activator protein 1 (AP-1) pathway by increasing the phosphorylation of ERK (p-ERK), which enters the nucleus and promotes AP-1 transcription. The screening of the main proteins of the ERK pathway revealed that NSP14 could interact with MEK, a kinase of ERK, and increase the level of phosphorylated MEK. The addition of the MEK inhibitor U0126 suppressed the level of p-ERK induced by NSP14 and partly blocked cytokine production, suggesting that NSP14 activates MEK to enhance AP-1 signaling. Further investigation demonstrated that the ExoN domain of NSP14 might be crucial for the interaction and activation of MEK. These results suggest a novel mechanism by which NSP14 of SARS-CoV-2 induces a proinflammatory response in the host.

Single-cell RNA sequencing reveals a distinct profile of bone immune microenvironment and decreased osteoclast differentiation in type 2 diabetic mice.

The pathogenic effects of type 2 diabetes on bone tissue are gaining attention, but the cellular and molecular mechanisms underlying osteoimmunology are still unclear in diabetes-related bone diseases. We delineated the single-cell transcriptome of bone marrow cells from both wide type and type 2 diabetes mice, which provided the first detailed global profile of bone marrow cells and revealed a distinct bone immune microenvironment at the genetic level under type 2 diabetic condition. It was observed that osteoclast activity was inhibited due to a dysregulated cytokine network, which ultimately led to decreased osteoclast formation and differentiation. In type 2 diabetes mice, a specific C d 36 + cluster (cluster 18, monocytes/macrophages 2) was identified as the precursor of osteoclasts with diminished differentiation potential. AP-1 was demonstrated to be the key transcription factor in the underlying mechanism.

Revising pathogenesis of AP1S1-related MEDNIK syndrome: a missense variant in the AP1S1 gene as a causal genetic lesion.

MEDNIK syndrome is a rare autosomal recessive disease characterized by mental retardation, enteropathy, deafness, peripheral neuropathy, ichthyosis, and keratoderma, and caused by variants in the adaptor-related protein complex 1 subunit sigma 1 (AP1S1) gene. This gene encodes the σ1A protein, which is a subunit of the adaptor protein complex 1 (AP-1), a key component of the intracellular protein trafficking machinery. Previous work identified three AP1S1 nonsense, frameshift and splice-site variants in MEDNIK patients predicted to encode truncated σ1A proteins, with consequent AP-1 dysfunction. However, two AP1S1 missense variants (c.269 T > C and c.346G > A) were recently reported in patients who presented with severe enteropathy but no additional symptoms of MEDNIK. This condition was described as a novel non-syndromic form of congenital diarrhea caused specifically by the AP1S1 missense variants. In this study, we report two patients with the same c.269 T > C variant, who, contrary to the previous cases, presented as complete MEDNIK syndrome. These data substantially revise the presentation of disorders associated with AP1S1 gene variants and indicate that all the identified pathogenic AP1S1 variants result in MEDNIK syndrome. We also provide a series of functional analyses that elucidate the impact of the c.269 T > C variant on σ1A function, contributing to a better understanding of the molecular pathogenesis of MEDNIK syndrome. KEY MESSAGES: A missense AP1S1 c.269 T > C (σ1A L90P) variant causes full MEDNIK syndrome. The σ1A L90P variant is largely unable to assemble into the AP-1 complex. The σ1A L90P variant fails to bind [DE]XXXL[LI] sorting motifs. The σ1A L90P variant results in loss-of-function of the protein.

Exploration of the potential mechanism of aqueous extract of Artemisia capillaris for the treatment of non-alcoholic fatty liver disease based on network pharmacology and experimental verification.

OBJECTIVES: Non-alcoholic fatty liver disease (NAFLD) is a nutritional and metabolic disease with a high prevalence today. Artemisia capillaris has anti-inflammatory, antioxidant, and other effects. However, the mechanism of A. capillaris in treating NAFLD is still poorly understood. METHODS: This study explored the mechanism of A. capillaris in the treatment of NAFLD through network pharmacology and molecular docking, and verified the results through in vivo experiments using a high-fat diet-induced mouse model and in vitro experiments using an oleic acid-induced HepG2 cell model. KEY FINDINGS: Aqueous extract of A. capillaris (AEAC) can reduce blood lipids, reduce liver lipid accumulation and liver inflammation in NAFLD mice, and improve NAFLD. Network pharmacology analysis revealed that 51 drug ingredients in A. capillaris correspond to 370 targets that act on NAFLD. GEO data mining obtained 93 liver differentially expressed genes related to NAFLD. In the UHPLC-MS detection results, 36 components were characterized and molecular docked with JNK. Verified in vitro and in vivo, the results show that JNK and the phosphorylation levels of IL-6, IL-1ß, c-Jun, c-Fos, and CCL2 are key targets and pathways. CONCLUSIONS: This study confirmed that AEAC reduces lipid accumulation and inflammation in the liver of NAFLD mice by inhibiting the JNK/AP-1 pathway.

A non-canonical repressor function of JUN restrains YAP activity and liver cancer growth.

Yes-associated protein (YAP) and its homolog, transcriptional coactivator with PDZ-binding motif (TAZ), are the main transcriptional downstream effectors of the Hippo pathway. Decreased Hippo pathway activity leads to nuclear translocation of YAP/TAZ where they interact with TEAD transcription factors to induce target gene expression. Unrestrained YAP/TAZ activity can lead to excessive growth and tumor formation in a short time, underscoring the evolutionary need for tight control of these two transcriptional coactivators. Here, we report that the AP-1 component JUN acts as specific repressor of YAP/TAZ at joint target sites to decrease YAP/TAZ activity. This function of JUN is independent of its heterodimeric AP-1 partner FOS and the canonical AP-1 function. Since expression of JUN is itself induced by YAP/TAZ, our work identifies a JUN-dependent negative feedback loop that buffers YAP/TAZ activity at joint genomic sites. This negative feedback loop gets disrupted in liver cancer to unlock the full oncogenic potential of YAP/TAZ. Our results thus demonstrate an additional layer of control for the interplay of YAP/TAZ and AP-1.

Two-polarized roles of transcription factor FOSB in lung cancer progression and prognosis: dependent on p53 status.

BACKGROUND: Activator protein-1 (AP-1) represents a transcription factor family that has garnered growing attention for its extensive involvement in tumor biology. However, the roles of the AP-1 family in the evolution of lung cancer remain poorly characterized. FBJ Murine Osteosarcoma Viral Oncogene Homolog B (FOSB), a classic AP-1 family member, was previously reported to play bewilderingly two-polarized roles in non-small cell lung cancer (NSCLC) as an enigmatic double-edged sword, for which the reasons and significance warrant further elucidation. METHODS AND RESULTS: Based on the bioinformatics analysis of a large NSCLC cohort from the TCGA database, our current work found the well-known tumor suppressor gene TP53 served as a key code to decipher the two sides of FOSB - its expression indicated a positive prognosis in NSCLC patients harboring wild-type TP53 while a negative one in those harboring mutant TP53. By constructing a panel of syngeneically derived NSCLC cells expressing p53 in different statuses, the radically opposite prognostic effects of FOSB expression in NSCLC population were validated, with the TP53-R248Q mutation site emerging as particularly meaningful. Transcriptome sequencing showed that FOSB overexpression elicited diversifying transcriptomic landscapes across NSCLC cells with varying genetic backgrounds of TP53 and, combined with the validation by RT-qPCR, PREX1 (TP53-Null), IGFBP5 (TP53-WT), AKR1C3, and ALDH3A1 (TP53-R248Q) were respectively identified as p53-dependent transcriptional targets of FOSB. Subsequently, the heterogenous impacts of FOSB on the tumor biology in NSCLC cells via the above selective transcriptional targets were confirmed in vitro and in vivo. Mechanistic investigations revealed that wild-type or mutant p53 might guide FOSB to recognize and bind to distinct promoter sequences via protein-protein interactions to transcriptionally activate specific target genes, thereby creating disparate influences on the progression and prognosis in NSCLC. CONCLUSIONS: FOSB expression holds promise as a novel prognostic biomarker for NSCLC in combination with a given genetic background of TP53, and the unique interactions between FOSB and p53 may serve as underlying intervention targets for NSCLC.

The JNK and Hippo pathways control epithelial integrity and prevent tumor initiation by regulating an overlapping transcriptome.

Epithelial organs maintain their integrity and prevent tumor initiation by actively removing defective cells, such as those that have lost apicobasal polarity. Here, we identify how transcription factors of two key signaling pathways-Jun-N-terminal kinase (JNK) and Hippo-regulate epithelial integrity by controlling transcription of an overlapping set of target genes. Targeted DamID experiments reveal that, in proliferating cells of the Drosophila melanogaster eye, the AP-1 transcription factor Jun and the Hippo pathway transcription regulators Yorkie and Scalloped bind to a common suite of target genes that promote organ growth. In defective neoplastic cells, AP-1 transcription factors repress transcription of growth genes together with the C-terminal binding protein (CtBP) co-repressor. If gene repression by AP-1/CtBP fails, neoplastic tumor growth ensues, driven by Yorkie/Scalloped. Thus, AP-1/CtBP eliminates defective cells and prevents tumor initiation by acting in parallel to Yorkie/Scalloped to repress expression of a shared transcriptome. These findings shed new light on the maintenance of epithelial integrity and tumor suppression.

Neuroprotective effect of diosmin against chlorpyrifos-induced brain intoxication was mediated by regulating PPAR-γ and NF-κB/AP-1 signals.

Chlorpyrifos (CPF) is a widely used organophosphate (OP) pesticide. Unfortunately, pesticides are known to cause neuronal intoxication. Diosmin (DS) is an antioxidant, anti-inflammatory, and neuroprotective flavonoid with high efficacy and safety. We plan to investigate the efficacy of DS in treating CPF-induced neurotoxicity, as well as the mechanisms underlying the protective effects. In our study, rats were randomized into 5 groups: control, DS (50 mg/kg), CPF (10 mg/kg), CPF + DS (25 mg/kg), and CPF + DS (50 mg/kg). The results indicated that DS ameliorated neuronal intoxication induced by CPF, evidenced by decreasing Tau, p-Tau, and ß-amyloid. Histological examinations support these findings. DS significantly ameliorated CPF-induced neuronal oxidative injury by decreasing MDA content and elevating GSH, GST, and SOD levels mediated by PPAR-γ upregulation. DS suppressed CPF-induced brain inflammation by decreasing MPO enzymatic activity and TNF-α, IL-1ß, and IL-6 levels mediated by downregulation of NF-κB/AP-1(c-FOS and c-JUN) signal. Of note, DS protective effects were dose dependent. In conclusion, our data suggested that DS was a promising therapeutic strategy for attenuating CPF-induced neuronal intoxication by restoring oxidant-antioxidant balance and inhibiting inflammatory response in brain tissues.

EWS-FLI1 and Activator Protein-1 (AP-1) Reciprocally Regulate Extracellular-Matrix Proteins in Ewing sarcoma Cells.

Ribonucleotide reductase (RNR) is the rate-limiting enzyme in the synthesis of deoxyribonucleotides and the target of multiple chemotherapy drugs, including gemcitabine. We previously identified that inhibition of RNR in Ewing sarcoma tumors upregulates the expression levels of multiple members of the activator protein-1 (AP-1) transcription factor family, including c-Jun and c-Fos, and downregulates the expression of c-Myc. However, the broader functions and downstream targets of AP-1, which are highly context- and cell-dependent, are unknown in Ewing sarcoma tumors. Consequently, in this work, we used genetically defined models, transcriptome profiling, and gene-set -enrichment analysis to identify that AP-1 and EWS-FLI1, the driver oncogene in most Ewing sarcoma tumors, reciprocally regulate the expression of multiple extracellular-matrix proteins, including fibronectins, integrins, and collagens. AP-1 expression in Ewing sarcoma cells also drives, concurrent with these perturbations in gene and protein expression, changes in cell morphology and phenotype. We also identified that EWS-FLI1 dysregulates the expression of multiple AP-1 proteins, aligning with previous reports demonstrating genetic and physical interactions between EWS-FLI1 and AP-1. Overall, these results provide novel insights into the distinct, EWS-FLI1-dependent features of Ewing sarcoma tumors and identify a novel, reciprocal regulation of extracellular-matrix components by EWS-FLI1 and AP-1.

CRKL Enhances YAP Signaling through Binding and JNK/JUN Pathway Activation in Liver Cancer.

The Hippo pathway transducers yes-associated protein (YAP) and WW-domain containing transcription regulator 1 (WWTR1/TAZ) are key regulators of liver tumorigenesis, promoting tumor formation and progression. Although the first inhibitors are in clinical trials, targeting the relevant upstream regulators of YAP/TAZ activity could prove equally beneficial. To identify regulators of YAP/TAZ activity in hepatocarcinoma (HCC) cells, we carried out a proximity labelling approach (BioID) coupled with mass spectrometry. We verified CRK-like proto-oncogene adaptor protein (CRKL) as a new YAP-exclusive interaction partner. CRKL is highly expressed in HCC patients, and its expression is associated with YAP activity as well as poor survival prognosis. In vitro experiments demonstrated CRKL-dependent cell survival and the loss of YAP binding induced through actin disruption. Moreover, we delineated the activation of the JNK/JUN pathway by CRKL, which promoted YAP transcription. Our data illustrate that CRKL not only promoted YAP activity through its binding but also through the induction of YAP transcription by JNK/JUN activation. This emphasizes the potential use of targeting the JNK/JUN pathway to suppress YAP expression in HCC patients.

Dynamic regulation of tissue fluidity controls skin repair during wound healing.

During wound healing, different pools of stem cells (SCs) contribute to skin repair. However, how SCs become activated and drive the tissue remodeling essential for skin repair is still poorly understood. Here, by developing a mouse model allowing lineage tracing and basal cell lineage ablation, we monitor SC fate and tissue dynamics during regeneration using confocal and intravital imaging. Analysis of basal cell rearrangements shows dynamic transitions from a solid-like homeostatic state to a fluid-like state allowing tissue remodeling during repair, as predicted by a minimal mathematical modeling of the spatiotemporal dynamics and fate behavior of basal cells. The basal cell layer progressively returns to a solid-like state with re-epithelialization. Bulk, single-cell RNA, and epigenetic profiling of SCs, together with functional experiments, uncover a common regenerative state regulated by the EGFR/AP1 axis activated during tissue fluidization that is essential for skin SC activation and tissue repair.