Open PhD position at the Institute of Cell Biology, Medical University of Innsbruck, Austria
We offer 1 fully funded PhD position with immediate effect located at the Institute of Cell Biology, Biocenter, Medical University of Innsbruck and supervised by Ass.-Prof. Georg-Friedrich Vogel (Cell Biology, Paediatrics I). The project is embedded within the PhD program Molecular and Cellular Basis of Diseases (MCBD) at the Medical University of Innsbruck, Austria. This interdisciplinary PhD program addresses the molecular control of metabolism & inflammation and connect basic life science and computational biology with medicine.
To read more about the program and the requirements, please use the following link:
Project: Delineating hepatocytic apical trafficking defects in cholestatic liver disease
In enterocytes, myo5b dependent apical trafficking has been precisely characterised in several studies, including our own. Myo5b interacts with the Rab small GTPases rab8a and rab11a in order to transport cargo vesicles to the apical plasma membrane. There, interaction with the exocyst subunit sec15 allows tethering of the vesicle and subsequent vesicle-plasma membrane fusion is mediated via a SNARE complex formed by vamp8, slp4a, STXBP2 and syntaxin3. The resulting cargo-mislocalisation gives rise to MVIDs enteropathy. Recently, our genetic analysis further identified mutations in STX3 and STXBP2 genes causative for microvillus inclusion disease (MVID).
In hepatocytes however, cargo trafficking to the apical bile canaliculus is understood to a far lesser degree. A study could show that both myo5B and rab11 are required for the formation of bile canaliculi. Defects in the establishment of proper hepatocyte polarity can result in liver disease. Further evidence was published recently showing that only missense, presumably via a dominant-negative effect, rather than nonsense mutations or loss of MYO5B cause MVID associated cholestatic liver disease (CLD). This implies that loss of myo5b does not affect apical trafficking. Furthermore, the apical SNARE protein syntaxin3 seems not be expressed in hepatocytes. How vesicles are shuttled towards the apical plasma membrane, hence the patho-mechanism of myo5b related CLD remains to be elucidated.
We hypothesize that apical cargo trafficking in hepatocytes is orchestrated by a protein machinery of different composition as compared to enterocytes. In order to better understand and develop potential disease modifying compounds, we plan to study the subcellular pathophysiology in detail. This project aims to characterize the several essential constituents of apical cargo transport in hepatocytes:
(i) Which motor protein is responsible for transport of vesicles leaving the Golgi/trans-Golgi compartments? (ii) Which are the vesicle-motor-adaptors involved (e.g. Rab small GTPases)? (iii) What is the composition of the trans-SNARE-complex at the apical face of the hepatocytes (that form the bile canaliculus)? (iv) How does experimental cholestasis match the clinical, serological and histopathological presentation of CLD patients?
The proposed research project will be carried out in the human hepatocyte cell line HepG2 which grows polarised and forms proper bile canaliculi between the cells, and will comprise protein localization and interaction studies, as well as functional assays on proper hepatocyte polarity formation and apical cargo transport.
Master Thesis: TOPIC: Functional implications of LAMTOR1 phosphorylation
Advisor: Prof Lukas A. Huber and MSc Isabel Singer
Institution: Institute of Cell Biology, Biocenter MUI, https://cellbiology.i-med.ac.at/
Contact: firstname.lastname@example.org, email@example.com
Start: Any time from March 2023 onwards
In recent years, the view of lysosomes as a cellular garbage disposal system has been extended by data underlying its importance in orchestrating cellular metabolism. Lysosomes are crucial for cell growth, proliferation, differentiation and cell-type specific processes, rendering proper lysosomal function indispensable for cellular homeostasis.
Lysosomes harbor a complex nutrient sensing machinery that integrates information about extra- and intracellular nutrient availability and activates corresponding signaling pathways, causing changes in the cell’s metabolic program. The LAMTOR [late endosomal/lysosomal adaptor and MAPK (mitogen-activated protein kinase) and mTOR (mechanistic target of Rapamycin) activator] complex plays a central role in these processes by recruiting and/or activating AMPK (AMP-activated protein kinase), MAPK and mTOR on the lysosomal surface.
In order to regulate these processes, LAMTOR associates with a number of partners including the Rag-GTPases, SLC38A9, the lysosomal v-ATPase, MEK, BORC, AXIN, LKB1, and many more. We know that some of these associations are mutually exclusive, whereas others occur under the same physiological conditions. We could show in previous work, that phosphorylation of the N-terminus of LAMTOR1 plays a role in regulating these interactions, however the functional trigger(s) for these events and their physiological consequences for the cell remain largely unknown.
The aim of this Master thesis, is to investigate these phosphorylation sites functionally. A large number of cell lines with different mutations are available for this purpose. Methods to be used include biochemical analysis, high resolution microscopy and basic molecular biology techniques.
We are looking for motivated young scientists to join our lab at the CCB Innsbruck for their Master thesis. We offer a collaborative lab atmosphere and thorough training in molecular cell biology, protein biochemistry and microscopy.
Master Thesis: TOPIC: A comparative analysis of different mTORopathies
Advisor: Mariana Eca Guimaraes de Araujo
Institution: Institute of Cell Biology, Biocenter, Mui, https://cellbiology.i-med.ac.at/
Start: Any time from March 2023 onwards
Most organisms have mechanisms for efficiently transitioning between anabolic and catabolic states, allowing them to survive and grow in environments in which nutrient availability is limited. In mammals, an example of such a mechanism is the signaling network coordinated by mTOR (Mechanistic target of rapamycin). Because mTORC1 triggers a rather resource-intensive anabolic program (growth/mass accumulation and proliferation), cells have evolved mechanisms to ensure that it becomes active only when sufficient resources are available. As such, lysosomal mTORC1 is activated as a coordinated response to amino acids, cholesterol and glucose availability. Despite decades of research, we are only now beginning to unravel the intricate cascade of events that control this cellular gatekeeper.
mTOR is involved in a wide variety of diseases, including cancer, obesity, type 2 diabetes, and neurodegeneration. Moreover, mutations in genes encoding for mTOR regulators (TSC1, TSC2, PTEN, AKT,
GATOR and KICSTOR components) result in a collection of neurodevelopmental disorders commonly known as mTORopathies. These diseases can affect multiple organs, but all have distinct neurological clinical presentations, including mental retardation, autism, and epilepsy.
Despite the mentioned similarities, there are obvious differences between the identified mTORopathies and it remains unclear if these arise from the degree of mTOR hyperactivation or if other deregulated pathways also contribute to the specific phenotypes
The aim of this project is, to perform a detailed comparative characterization of patient fibroblasts with mutations in different mTOR regulators. The analysis will include biochemical, molecular biology and fluorescence imaging methods.
We are looking for a highly motivated student with an interest in understanding the pathological mechanisms underlying rare human diseases. We offer a collaborative lab atmosphere and thorough training in molecular cell biology, protein biochemistry and microscopy.