Prolactin and growth hormone signaling

Area of Science:

• Endocrinology
• Molecular Biology
• Cell Signaling

Background:

• Prolactin (PRL) and growth hormone (GH) function systemically as hormones and locally as cytokines.
• Their signaling primarily occurs through the Janus kinase 2 (Jak2)/Signal transducer and activator of transcription 5 (Stat5) pathway.
• This pathway is crucial for activating target genes in response to PRL and GH.

Purpose of the Study:

• To review recent advances in Prolactin (PRL) and growth hormone (GH) signal transduction.
• To highlight the role of the Jak2/Stat5 pathway and its interactions.
• To discuss emerging regulatory mechanisms and alternative signaling routes.

Main Methods:

• Review of recent scientific literature on PRL and GH signaling.
• Analysis of data from knockout mouse models for signaling cascade members.
• Examination of evidence for alternative pathways like MAP kinase, PI3K/Akt, and Jak2/RUSH.

Main Results:

• The Jak2/Stat5 pathway is the principal route for PRL/GH-mediated gene activation.
• Jak2 also participates in alternative signaling pathways, including MAP kinase and PI3K/Akt.
• The Jak2/RUSH pathway is implicated in PRL's augmentation of progesterone-dependent gene transcription.
• New findings identify suppressors, regulators, and degraders that control Jak2/Stat5 activity.

Conclusions:

• The Jak2/Stat5 pathway remains central to PRL and GH action, with significant insights gained from genetic models.
• Alternative signaling pathways and novel regulatory factors (suppressors, regulators, degraders) add complexity to PRL/GH signal transduction.
• Continued research is vital for a comprehensive understanding of these intricate signaling networks.