Signalveje

Signalveje, in Danish, refers to networks of molecular interactions that convey information within cells and between cells, translating stimuli into functional responses. They organize how external cues such as nutrients, hormones, or stress, and internal states, are processed to regulate processes like metabolism, growth, differentiation, and apoptosis.

A typical signalvej begins with reception, where a signal molecule binds to a receptor on the cell surface or inside the cell. This event is followed by transduction, a cascade of molecular interactions often involving phosphorylation, second messengers, and changes in protein activity. Through amplification and integration with other signals, the information is refined before triggering an appropriate response, which can be changes in gene expression, enzyme activity, or cytoskeletal rearrangement. Many signalveje feature feedback loops and cross-talk with other pathways, shaping the dynamics and robustness of the response.

Signaling can be categorized by the initiating mechanism, the cellular location, and the type of response. Major classes include membrane-initiated pathways such as receptor tyrosine kinases and G protein‑coupled receptors, as well as intracellular receptors for lipophilic ligands. Intercellular signaling also occurs, including autocrine, paracrine, endocrine, and juxtacrine modes.

Numerical and spatial dynamics are important in signalveje: dose dependency, temporal patterns, and network topology influence outcomes. Dysregulation of signaling pathways is linked to diseases such as cancer, metabolic disorders, and neurodegeneration, making them common targets for therapeutic intervention. Classic examples of well-studied signalveje include MAPK/ERK, PI3K/Akt, JAK/STAT, TGF-β, Wnt, and Notch pathways.