Signaling via the CytoR/JAK/STAT/SOCS pathway: Emergence during evolution

Area of Science:

• Evolutionary biology
• Molecular biology
• Immunology

Background:

• Multicellular organisms rely on cell-cell signaling for communication, especially immune cells.
• The cytokine receptor/Janus kinase/Signal Transducer and Activator of Transcription/Suppressor of Cytokine Signaling (CytoR/JAK/STAT/SOCS) pathway is crucial for this signaling.
• Previous research focused on pathway function in vertebrates and protostomes, but its evolutionary origins remain unclear.

Purpose of the Study:

• To investigate the evolutionary origins of individual components within the CytoR/JAK/STAT/SOCS pathway.
• To understand how these components assembled over evolutionary time to form a functional signaling pathway.
• To determine the evolutionary models governing pathway assembly.

Main Methods:

• Bioinformatic analysis of pathway components across key extant species.
• Tracing the step-wise accretion of individual pathway elements.
• Comparative genomics to identify key evolutionary innovations.

Main Results:

• Individual components of the pathway were gradually acquired over a long evolutionary timescale.
• The complete CytoR/JAK/STAT pathway was finalized through a series of innovations specifically within Bilateria.
• Pathway assembly followed the retrograde model for CytoR/JAK/STAT components and the patchwork model for SOCS.

Conclusions:

• The CytoR/JAK/STAT/SOCS pathway evolved through a protracted process of component accretion and innovation.
• The emergence of a complete functional pathway was a significant evolutionary event in Bilateria.
• Different evolutionary models explain the assembly of distinct parts of this complex signaling system.