Transcription factor Jun (specifically, the c-Jun subunit of the AP-1 complex) (JUN)

JUN, known as transcription factor Jun or c-Jun, is a basic leucine zipper (bZIP) transcription factor and proto-oncogene that functions as a key component of the AP-1 transcription factor complex by dimerizing with Fos and other partners. JUN/AP-1 modulates gene expression in response to a wide range of extracellular signals—growth factors, cytokines, cellular stress, and UV—and mediates cellular outcomes such as proliferation, cell cycle control, apoptosis, immunity, and metabolic adaptation. Dysregulated JUN expression and activation are implicated in several types of cancer (notably acute myeloid leukemia and breast cancer), inflammation, and stress-related diseases, often through altered regulation of downstream effectors like the glutaminase gene GLS and Unfolded Protein Response mediators. Therapeutic targeting of JUN involves either direct inhibition of its activity (AP-1 complex formation, DNA binding) or modulation of upstream kinases, but remains challenging due to the physiological importance of JUN in normal cell function.

Other names

c-JunProto-oncogene protein c-JunAP-1 (Activator protein 1; when referring to the complex with Fos)Jun proto-oncogeneJun/AP-1 subunit

Blockade of dimerization (prevents formation of functional AP-1 complex, thus inhibiting DNA binding and target gene activation) Inhibition of phosphorylation via upstream kinases (JNK, ERK), preventing activation of c-Jun and its transcriptional programs Suppression of downstream transcriptional events (e.g., inhibition of the Unfolded Protein Response, glutaminase expression)