Myc

MYC is a family of regulator genes that encode transcription factors involved in cell growth, metabolism, and proliferation. The best known member is c-Myc, encoded by the MYC gene, with two related genes in vertebrates: MYCN (N-Myc) and MYCL (L-Myc). MYC proteins belong to the basic helix-loop-helix leucine zipper (bHLH-LZ) family and function as transcription factors that regulate a large network of target genes.

MYC proteins form functional dimers with MAX and bind to specific DNA motifs known as E-boxes (canonical sequence CACGTG) to control transcription. Through these interactions, they regulate genes involved in ribosome biogenesis, protein synthesis, metabolism, cell cycle progression, and differentiation. In many cells, MYC acts as a transcriptional amplifier, promoting broad changes in gene expression in response to growth signals.

Regulation of MYC activity is complex and occurs at multiple levels, including transcription, mRNA stability, translation, and protein degradation. Signaling pathways such as RAS/MAPK and PI3K/AKT influence MYC expression and activity, while ubiquitin-mediated pathways control its degradation. Because MYC activity is tightly tied to cell growth, its dysregulation can have profound consequences.

Clinical significance is substantial: MYC genes are frequently deregulated in cancer. Translocations or amplifications can lead to overexpression, as seen in Burkitt lymphoma (MYC translocated to immunoglobulin loci) and neuroblastoma (MYCN amplification). Due to its central role in proliferation, MYC is a major focus of cancer research, with strategies targeting MYC function or its downstream pathways under investigation, though direct, selective MYC inhibition remains challenging.