Jun proto-oncogene, AP-1 transcription factor subunit

Overview

Jun proto-oncogene, AP-1 transcription factor subunit (commonly JUN) encodes a major component of the activator protein-1 (AP-1) transcription factor complex. JUN is a nuclear transcriptional regulator that integrates signals from multiple upstream pathways, including MAPK signaling, PI3K/Akt signaling pathway, inflammatory cascades, and stress responses. By forming homo- or heterodimers with other AP-1 family proteins, JUN helps control gene expression programs involved in cell proliferation, differentiation, survival, migration, and inflammatory activation.

Biomedically, JUN is widely studied as a proto-oncogene because AP-1 activity can support tumor growth, invasion, and adaptation to stress. At the same time, JUN is also implicated in nonmalignant disease processes such as inflammation, fibrosis, and vascular remodeling. Its activity is often assessed in relation to downstream transcriptional programs involving MYC, STAT3, nuclear factor kappa B, B-cell lymphoma 2, Interleukin 1 beta, and matrix-remodeling genes such as MMP9, reflecting its role as a central signaling node rather than a disease-specific effector.

Role in Recent Research

Recent studies have continued to position JUN/AP-1 as a convergent regulator in cancer biology, inflammatory disease, and tissue remodeling. In a study of APC/TP53 double-knockout human colon organoids (PMID: 42401564), activation of KIT signaling was reported to promote early tumorigenesis through the AP-1 pathway. The authors described this as an AP-1/KIT signaling axis central to early progression of colorectal cancer, suggesting a potential therapeutic entry point in a model that combined organoid biology with oncogenic signaling analysis.

Several studies used network pharmacology and bioinformatics to identify JUN as a hub gene or regulatory node. In a nutraceutical formula study (PMID: 42384725), STRING and Cytoscape-based protein-protein interaction analysis identified JUN among fourteen hub nodes, alongside Akt1, BCL2, CASP3, CTNNB1, EGFR, ESR1, HSP90AA1, HSP90AB1, IL6, SRC, STAT3, and TNF. This places JUN within a broader cancer-associated interaction network rather than as a single isolated target. Similarly, in a cross-ecosystem host-pathway analysis (PMID: 42249966), JUN was identified as one of the conserved regulatory hubs linking microbial perturbations to cardiometabolic and inflammatory disease pathways, together with PPARG, CDC42, RHOA, and CAV1.

In kidney disease research (PMID: 42135973), JUN emerged as one of six hub genes in a bioinformatics analysis of pyroptosis-related differentially expressed genes in IgA nephropathy. Using methods including limma, LASSO regression, and SVM algorithms applied to GEO database data such as GSE99339, the study reported that JUN, along with BHLHE40, CEBPB, ACE2, IL1B, and CD14, showed high diagnostic accuracy for distinguishing IgA nephropathy from normal samples. This supports JUN’s relevance as part of an inflammatory transcriptional signature in renal pathology.

JUN/AP-1 was also implicated in multiple disease models involving tissue remodeling and inflammation. In proliferative diabetic retinopathy (PMID: 41805865), ANGPTL4 was reported to activate the AP-1 transcription factor complex and promote Cd83 transcription in human lymphatic endothelial cells and mouse heart microvascular endothelial cells, linking AP-1 activity to aberrant lymphatic-like remodeling. In bladder and colon cancer cells (PMID: 42049325), inhibition of AP-1 reduced CD46-mediated invasion, with CD46 ultimately activating phosphorylation of the AP-1 complex to stimulate MMP9 expression. In invasive lobular carcinoma (PMID: 41706704), LOX inhibition disrupted a collagen-integrin-MYC axis and downregulated MYC, NF-κB, and AP-1 transcriptional programs, indicating that AP-1 participates in extracellular matrix-driven oncogenic signaling.

Experimental and pharmacologic studies further support JUN/AP-1 as a modifiable target. In a study of type II collagen-induced arthritis (PMID: 42062033), Murraya exotica L. extract suppressed AP-1 activation by downregulating c-Fos and c-Jun, while also inhibiting NF-κB signaling through reduced IκBα phosphorylation and degradation and prevention of p65 nuclear translocation. In another inflammatory context, pyrrolidinedithiocarbamate and SR11302 were among the tools and compounds associated with AP-1 inhibition research, reflecting the use of direct or pathway-level suppression strategies. Additional methods and platforms linked to JUN-focused studies included cellular thermal shift assay, drug affinity responsive target stability, CRISPR-Cas12a, centrality metrics, and multilayer network integration framework, underscoring the breadth of experimental and computational approaches used to interrogate AP-1 biology.

Overall, the recent literature portrays JUN as a central AP-1 subunit involved in oncogenic transcription, inflammatory signaling, and remodeling processes across cancer, kidney disease, retinal disease, and arthritis. Its recurring appearance alongside PI3K/Akt signaling pathway, mitogen-activated protein kinase 14, nuclear factor kappa B, STAT3, ESR1, MYC, and collagen-associated pathways highlights its role as a transcriptional hub that integrates extracellular cues into disease-relevant gene expression programs.

Key Publications

NEWJul Activation of KIT signaling promotes early tumorigenesis through the AP-1 pathway in APC/TP53 double-knockout human colon organoids. (Cell death & disease, 2026, PMID 42401564): "Furthermore, AP-1 transcription factors (FOS/JUN) regulate KIT expression via chromatin remodeling."
NEWJul A network pharmacology-based approach and molecular docking study to explore the therapeutic potential of a nutraceutical formula (Vernolac) in the treatment of cancer. (PloS one, 2026, PMID 42384725): "Protein-protein interaction analysis using STRING and Cytoscape revealed fourteen key hub nodes, including AKT1, BCL2, CASP3, CTNNB1, EGFR, ESR1, GAPDH, HSP90AA1, HSP90AB1, IL6, JUN, SRC, STAT3, and TNF."
Jun Network pharmacology identifies repurposable drugs targeting host pathways across the oral-gut-lung axis. (Naunyn-Schmiedeberg's archives of pharmacology, 2026, PMID 42249966): "The integrative framework identified conserved cross-ecosystem regulatory hubs, including PPARG, CDC42, JUN, RHOA, and CAV1, which link microbial perturbations to cardiometabolic and inflammatory disease pathways."
Dec Identification of pyroptosis-related hub genes and immune cell infiltration in IgA nephropathy via bioinformatics analysis. (Renal failure, 2026, PMID 42135973): "A total of 19 pyroptosis-related differentially expressed genes (nine up-regulated and 10 down-regulated) were identified, with six hub genes (BHLHE40, JUN, CEBPB, ACE2, IL1B, and CD14) showing high diagnostic accuracy for discriminating IgAN from normal samples (AUC > 0.9)."
May LOX Inhibition Disrupts a Collagen-Integrin-MYC Axis to Suppress Progression of Invasive Lobular Carcinoma. (Cancer research, 2026, PMID 41706704): "...and LOX inhibition downregulated their expression, together with MYC, NF-κB, and AP-1 transcriptional programs."
May ANGPTL4 Induces Aberrant Lymphatic-Like Remodeling in Proliferative Diabetic Retinopathy. (Diabetes, 2026, PMID 41805865): "...which activated the activator protein-1 (AP-1) transcription factor complex and promoted Cd83 transcription in mouse heart microvascular endothelial cells."
May Inhibition of AP-1 Reduces CD46-mediated Invasion of Bladder and Colon Cancer Cells. (Anticancer research, 2026, PMID 42049325): "CD46 ultimately activated the phosphorylation of the AP-1 complex to stimulate the expression of MMP9."
May Potential therapeutic benefits of Murraya exotica L. extract on type II collagen-induced arthritis. (Chinese journal of natural medicines, 2026, PMID 42062033): "Mechanistically, ME blocked NF-κB activation by inhibiting phosphorylation and degradation of inhibitor of NF-κB-α (IκBα) and preventing p65 nuclear translocation, while simultaneously suppressing activator protein-1 (AP-1) activation through downregulation of c-Fos and c-Jun."