Related Experiment Video

Updated: Jun 12, 2026

Induction and Diagnosis of Tumors in Drosophila Imaginal Disc Epithelia
08:14

Induction and Diagnosis of Tumors in Drosophila Imaginal Disc Epithelia

Published on: July 25, 2017

Characterization of a dominant-active STAT that promotes tumorigenesis in Drosophila

Laura A Ekas1, Timothy J Cardozo, Maria Sol Flaherty

  • 1Pharmacology Department, New York University School of Medicine, New York, New York 10016-6402, USA.

Developmental Biology
|May 27, 2010
PubMed

Insights

Researchers identified a constitutively active Signal Transducer and Activator of Transcription (STAT) protein in Drosophila, Stat92E(DeltaNDeltaC), which promotes tumor formation. This study reveals novel negative regulatory roles for STAT protein termini and identifies a critical DNA-binding domain residue conserved across species.

Area of Science:

  • Molecular Biology
  • Genetics
  • Cancer Research

Background:

  • Signal Transducer and Activator of Transcription (STAT) proteins are crucial in cellular signaling pathways.
  • Dysregulation of STAT proteins is implicated in various human cancers, but their precise oncogenic mechanisms remain largely unknown.
  • The fruit fly, Drosophila melanogaster, offers a powerful model system to study STAT function due to its single STAT gene, Stat92E, whose hyperactivation mimics tumor development.

Purpose of the Study:

  • To identify and characterize novel dominant-active forms of Stat92E.
  • To elucidate the molecular mechanisms underlying STAT-mediated tumorigenesis.
  • To investigate the functional significance of specific domains and residues within Stat92E.

Main Methods:

  • Generation and expression of a truncated, dominant-active Stat92E mutant (Stat92E(DeltaNDeltaC)).
  • In vivo studies using Drosophila to assess tumor formation (melanotic tumors).
  • In vitro reporter assays (Stat92E-luciferase) to measure transcriptional activity.
  • Site-directed mutagenesis to investigate the role of specific residues (e.g., R442P).
  • Protein modeling to predict DNA-binding interactions.

Main Results:

  • The N- and C-termini-deleted Stat92E (Stat92E(DeltaNDeltaC)) exhibits dominant-active, gain-of-function phenotypes, inducing melanotic tumors in vivo and constitutive reporter gene activation in vitro.
  • Gain-of-function phenotypes are dependent on Y711 phosphorylation and dimer formation with endogenous full-length Stat92E.
  • A specific point mutation (R442P) within the DNA-binding domain completely abrogates Stat92E function, despite nuclear translocation upon activation.
  • The R442 residue is conserved in STAT proteins of higher organisms, suggesting a conserved functional role.
  • Structural modeling suggests R442 interacts with the minor groove of DNA.

Conclusions:

  • The N- and C-termini of Stat92E unexpectedly act as negative regulators of its activity, potentially by modulating dephosphorylation or DNA-binding stability.
  • The R442 residue in the DNA-binding domain is essential for Stat92E's nuclear function, specifically in dimer:DNA binding.
  • These findings provide critical insights into STAT protein regulation and function in tumorigenesis, with potential implications for human cancer research.

More Related Videos

The Drosophila Imaginal Disc Tumor Model: Visualization and Quantification of Gene Expression and Tumor Invasiveness Using Genetic Mosaics10:31

The Drosophila Imaginal Disc Tumor Model: Visualization and Quantification of Gene Expression and Tumor Invasiveness Using Genetic Mosaics

Published on: October 6, 2016

A Protocol for Genetic Induction and Visualization of Benign and Invasive Tumors in Cephalic Complexes of Drosophila melanogaster07:23

A Protocol for Genetic Induction and Visualization of Benign and Invasive Tumors in Cephalic Complexes of Drosophila melanogaster

Published on: September 11, 2013

Related Concept Videos

Abnormal Proliferation02:23

Abnormal Proliferation

Under normal conditions, most adult cells remain in a non-proliferative state unless stimulated by internal or external factors to replace lost cells. Abnormal cell proliferation is a condition in which the cell's growth exceeds and is uncoordinated with normal cells. In such situations, cell division persists in the same excessive manner even after cessation of the stimuli, leading to persistent tumors. The tumor arises from the damaged cells that replicate to pass the damage to the daughter...
The Ras Gene02:38

The Ras Gene

The Ras-gene-encoded proteins are regulators of signaling pathways controlling cell proliferation, differentiation, or cell survival. The Ras-gene family in humans constitutes three primary members—the HRas, NRas, and KRas. These genes code for four functionally distinct yet closely related proteins—the HRas, NRas, KRas4A, and KRas4B. The involvement of mutant Ras genes in human cancer was first discovered in 1982 and is among the most common causes of human tumorigenesis.
Ras is a superfamily...
The JAK-STAT Signaling Pathway01:20

The JAK-STAT Signaling Pathway

Several cytokine receptors have tightly bound Janus kinase or JAK proteins attached at their cytosolic tail. Small signaling molecules such as cytokines, growth hormones, or prolactins bind to the cytokine receptors and initiate their dimerization. The dimerization brings the cytosolic JAKs together that trans-phosphorylate and activates each other. The activated JAKs now phosphorylate cytosolic tails of the cytokine receptors, which serve as binding sites for adaptor proteins such as  SH2...
mTOR Signaling and Cancer Progression03:03

mTOR Signaling and Cancer Progression

The mammalian target of rapamycin or mTOR protein was discovered in 1994 due to its direct interaction with rapamycin. The protein gets its name from a yeast homolog called TOR. The mTOR protein complex in mammalian cells plays a major role in balancing anabolic processes such as the synthesis of proteins, lipids, and nucleotides and catabolic processes, such as autophagy in response to environmental cues, such as availability of nutrients and growth factors.
The mTOR pathway or the...