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Updated: Mar 26, 2026
Immunostaining of Whole-Mount Drosophila Testes for 3D Confocal Analysis of Large Spermatocytes
Published on: August 27, 2020
The novel tumour suppressor Madm regulates stem cell competition in the Drosophila testis
Shree Ram Singh1, Ying Liu1, Jiangsha Zhao1
1The Basic Research Laboratory, National Cancer Institute, National Institutes of Health, Frederick, Maryland 21702, USA.
Abstract:
Stem cell competition has emerged as a mechanism for selecting fit stem cells/progenitors and controlling tumourigenesis. However, little is known about the underlying molecular mechanism. Here we identify Mlf1-adaptor molecule (Madm), a novel tumour suppressor that regulates the competition between germline stem cells (GSCs) and somatic cyst stem cells (CySCs) for niche occupancy. Madm knockdown results in overexpression of the EGF receptor ligand vein (vn), which further activates EGF receptor signalling and integrin expression non-cell autonomously in CySCs to promote their overproliferation and ability to outcompete GSCs for niche occupancy. Conversely, expressing a constitutively activated form of the Drosophila JAK kinase (hop(Tum-l)) promotes Madm nuclear translocation, and suppresses vn and integrin expression in CySCs that allows GSCs to outcompete CySCs for niche occupancy and promotes GSC tumour formation. Tumour suppressor-mediated stem cell competition presented here could be a mechanism of tumour initiation in mammals.
Insights
A novel tumor suppressor, Madm, regulates stem cell competition. Madm knockdown in somatic cyst stem cells (CySCs) drives overproliferation, enabling them to outcompete germline stem cells (GSCs) and initiate tumors.
Area of Science:
- Developmental Biology
- Cancer Biology
- Stem Cell Biology
Background:
- Stem cell competition is a key mechanism for maintaining tissue homeostasis and preventing tumor formation.
- The molecular underpinnings of stem cell competition and its role in tumorigenesis remain largely unexplored.
Purpose of the Study:
- To identify novel molecular regulators of stem cell competition.
- To elucidate the mechanism by which stem cell competition controls tumor initiation.
Main Methods:
- Utilized Drosophila melanogaster as a model organism.
- Investigated the role of Mlf1-adaptor molecule (Madm) in regulating germline stem cell (GSC) and somatic cyst stem cell (CySC) interactions.
- Analyzed gene expression and signaling pathways, including EGF receptor and JAK/STAT pathways.
Main Results:
- Identified Madm as a novel tumor suppressor regulating stem cell competition.
- Madm knockdown leads to overexpression of the EGF receptor ligand vein (vn), promoting CySC overproliferation and competitive advantage.
- Constitutively active JAK kinase (hopTum-l) promotes Madm nuclear translocation, suppressing CySC proliferation and favoring GSC competition, leading to GSC tumor formation.
Conclusions:
- Madm-mediated regulation of stem cell competition is a critical mechanism for controlling stem cell behavior and preventing tumor initiation.
- Dysregulation of this pathway can lead to stem cell overproliferation and tumor formation.
- This study provides insights into potential therapeutic strategies targeting stem cell competition in cancer treatment.
