The interconnected KIT receptor and Microphthalmia-associated transcription factor axis in melanoma
Author
Summary, in English
understand the molecular basis of disease development we studied the mechanisms that gatekeep and finetune the activity of both KIT and MITF.
In this thesis we have identified novel KIT ligand-dependent signaling pathways that, through MITF, affect cell proliferation. Notably, we found that the specific KIT tyrosine phosphorylation sites Y721 (PI3 kinase binding site), Y568 and Y570 (SRC binding sites) affect phosphorylation status of the MITF protein. Using
inhibitors against SRC, PI3K, AKT, MEK ERK and p38 during KIT activation, we identified that these signaling pathways are essential components in communicating signals between KIT and MITF.
The activity of KIT is regulated by the tetrapeptide insert in the extracellular juxtamembrane domain of the
receptor. By generating receptor mutants with different insert lengths, we showed that the length of this insert is critical for the fine tuning of receptor activation.
Using mass spectrometry and phospho-site specific antibodies against MITF, we found and characterized several serine and tyrosine phosphorylation sites in the protein. More importantly, in stark contrast to previous results, we discovered that the S73 and S409 phosphorylation sites of MITF are neither dependent
on KIT nor MAPK-ERK signaling. Furthermore, we show that the tyrosine phosphorylation sites of MITF are required for oncogenic KIT signaling and affect nuclear localization of MITF.
The structural properties of MITF and the KIT receptor were also clarified. By solving the crystal structure of MITF we explain the restricted heterodimerization of MITF towards TFEB, TFEC and TFE3, the binding of M-box DNA sequence and the ability to produce interallelic complementation.
In short, the detailing of KIT and MITF regulation has increased our understanding of key signaling
processes that are important to understand the development of melanoma.
Department/s
- Department of Translational Medicine
- BioCARE: Biomarkers in Cancer Medicine improving Health Care, Education and Innovation
Publishing year
2013
Language
English
Publication/Series
Lund University Faculty of Medicine Doctoral Dissertation Series
Volume
2013:82
Full text
Document type
Dissertation
Publisher
Experimental Clinical Chemistry
Topic
- Medicinal Chemistry
Status
Published
Supervisor
- Lars Rönnstrand
- Eiríkur Steingrímsson
- Jianmin Sun
ISBN/ISSN/Other
- ISSN: 1652-8220
- ISBN: 978-91-87449-54-3
Defence date
6 September 2013
Defence time
13:15
Defence place
Clinical Research Centre lecture hall, Malmö
Opponent
- Arne Östman (Professor)