Prolaktinsignalering

Prolaktinsignalering describes the molecular pathways initiated when prolactin, a hormone produced by the anterior pituitary gland, binds to its receptor on target cells. This binding event triggers a cascade of intracellular events that ultimately influence a wide range of physiological processes. The prolactin receptor is a transmembrane protein belonging to the cytokine receptor superfamily. Upon prolactin binding, the receptor undergoes a conformational change, leading to the activation of associated Janus kinases (JAKs), particularly JAK2.

Activated JAKs then phosphorylate tyrosine residues on the receptor itself, creating docking sites for other signaling proteins. The signal transducer and activator of transcription (STAT) family of proteins is a key downstream effector. STAT proteins, such as STAT1, STAT3, and STAT5, are recruited to the phosphorylated receptor and subsequently phosphorylated by the JAKs. Phosphorylated STATs then dimerize and translocate to the nucleus, where they bind to specific DNA sequences and regulate the transcription of target genes.

Beyond the JAK-STAT pathway, prolaktinsignalering also involves other signaling cascades. The phosphatidylinositol 3-kinase (PI3K)/Akt pathway is activated, contributing to cell survival and proliferation. Additionally, mitogen-activated protein kinase (MAPK) pathways, such as the ERK pathway, can be engaged, influencing cell growth and differentiation. The specific cellular response to prolactin depends on the cell type and the interplay of these various signaling molecules. Prolaktinsignalering is crucial for lactation, mammary gland development, immune function, and reproductive processes. Dysregulation of this signaling pathway is implicated in various endocrine disorders.