Opposing roles for Drosophila JAK/STAT signalling during cellular proliferation

Area of Science:

• Cell Biology
• Developmental Biology
• Genetics

Background:

• The Janus kinase/signal transducer and activator of transcription (JAK/STAT) signaling pathway is crucial for cellular responses to cytokines and interferons.
• Dysregulation of STAT molecules is linked to various cancers.
• Drosophila possesses a single STAT gene, STAT92E, offering a model to study conserved JAK/STAT functions.

Purpose of the Study:

• To investigate the role of Drosophila STAT92E in cell proliferation during development.
• To understand the dual pro- and antiproliferative functions of STAT92E within the JAK/STAT cascade.

Main Methods:

• Analysis of STAT92E activity in Drosophila larval wing discs.
• Investigating the effects of canonical and noncanonical STAT92E activation on cell proliferation.
• Cell cycle analysis to determine effects on cell cycle phases.

Main Results:

• STAT92E signaling is essential for epithelial cell proliferation in early larval stages.
• Later in development, STAT92E is activated via a noncanonical mechanism to inhibit proliferation.
• Ectopic canonical activation of STAT92E causes G2 cell cycle arrest and reduces proliferation.

Conclusions:

• Drosophila STAT92E exhibits both pro-proliferative and antiproliferative functions, analogous to vertebrate STAT3 and STAT1, respectively.
• These dual roles represent ancestral functions of the JAK/STAT pathway conserved through evolution.
• Distinct STAT molecules in vertebrates may have evolved from a single ancestral gene with dual functions.