Project-1:
Export from the endoplasmic reticulum (ER) is mediated by COPII vesicles that form on ER exit sites. COPII vesicles transfer cargo via the ERGIC to the Golgi. The formation of COPII vesicles is not only a constitutive process, but research by us and others showed that it is regulated by signaling pathways that are activated in response to extracellular stimuli (see Farhan, J Cell Biol, 2016 for an overview). This enables cells to tune the rate of secretion in response to the availability of nutrients and growth factors. Whether signaling pathways exits that are activated at the secretory pathway and signal to the secretory pathway remains elusive. We have identified recently identified a receptor tyrosine kinase called LTK that localizes to the ER and signals at this compartment. This is the first example of an autochthonous signaling circuit at the ER.
Goal of the project:
- Characterize the mechanism of action of LTK: what stimuli activate LTK and what does LTK signal to.
- How is LTK regulated? After LTK is activated, it must be de-activated to enable fine-tuning it’s signaling. This might be achieved either by a phosphatase or by a ubiquitiylation and degradation of LTK. Whether any of these scenarios is true will be investigated experimentally
- Investigate the de-regulation of LTK signaling in the regulation of cancer cell growth
Project-2:
The small GTPase Cdc42 is a major regulator of cell polarity., directional cell migration and cell invasion. Most research so far has focused on the Cdc42 signaling at the plasma membrane. However, Cdc42 localizes to endomembranes, but these subcellular pools remain incompletely understood. We have recently characterized the role of Cdc42 at the Golgi in cell polarity and cancer (Baschieri et al, Nature Communications, 2014).
Goal of the project:
- Map the interactome of Cdc42 at the Golgi and at the ER
- Characterize novel interaction partners and explore their role in different cellular processes such as secretion and cell migration
- Identify regulators of the subcellular pools of Cdc42
Methods of the Farhan group:
- We use several microscopy assays to study membrane dynamics such as the RUSH assay, FRAP (fluorescence recovery after photobleaching) and immunofluorescence.
- We use fluorescent biosensors to study spatial signaling that are based on FRET
- We often use YFP-BiFC (bimolecular fluorescence complementation) to study protein-protein interactions
- We further use standard biochemical and molecular biology methods such as immunoblotting, immunoprecipitation GST-pulldown, PCR cloning, etc…
- Many of our projects require bioinformatics and computational modeling using software and databases such as Cytoscape, STRING, DAVID, etc…