PhD student profiles

     
     
Lisa

Lisa Redlingshoefer
Wellcome Trust 4-year Interdisciplinary PhD Programme, beginning in Autumn 2013

Project title
The role of clathrin light chains in the diversification of clathrin function

Principle investigator: Professor Frances Brodsky, Structural and Molecular Biology, UCL

 
Background

For my undergraduate degree I studied biochemistry in Tuebingen to obtain a German diploma degree, which is similar to a combined Bachelor and Master programme. The first two years comprised fundamental courses in biology, physics, maths, anatomy, plant biochemistry, biochemistry, inorganic, organic and physical chemistry. During the advanced period of my studies, I specialized in organic chemistry and patho-biochemistry. I interned in various labs in and outside Germany during that time and decided to go abroad for my PhD.

 
Rotation projects

Rotation 1: Prof Peter Coveney, Department of Chemistry, UCL
Towards a structural understanding of the interactions of APOBEC-3G with HIV-1 proteins

Rotation 2: Dr James Baker, Department of Chemistry, UCL
New Methods to Photochemically Activate Peptides

Rotation 3: Prof Frances Brodsky, Research Department of Structural and Molecular Biology, UCL
Dysregulation of CHC22 clathrin in diabetes
 
PhD Project

I work in Professor Frances Brodsky’s lab, where our research is focused on clathrin proteins, using approaches from various angles, ranging from protein biochemistry to cell biology and physiology.

The canonical form of clathrin is formed by trimerisation of clathrin heavy chains (CHCs), associated with clathrin light chain (CLC) subunits, into a three-legged structure called triskelion, which can self-assemble into a polyhedral lattice. The role of this lattice is to “trap” integral membrane cargo for sequestration into transport vesicles or for sorting into membrane domains. To date, little is known about the roles of the CLC subunits in this process and the functional differences of CLC isoforms.

We have developed biochemical strategies to produce clathrin with single CLC isoforms. The main focus of my PhD research is to test the biophysical properties of these single-CLC isoform clathrin complexes to assess how they influence cage size and structure. To this end, we are assessing triskelion stability, cage morphology and ability to form clathrin-coated vesicles. This shall give us insight into the strength added to the clathrin lattice by CLCs, which we hypothesize influences cargo internalisation.

The CLCs bind the actin-organizing proteins Hip1 and Hip1R, linking clathrin to the actin cytoskeleton in order to allow for curvature of more rigid membrane and internalisation of large cargo. Recently, we demonstrated a role for the CLC-Hip interaction in cell migration, potentially explaining the observation of metastatic behaviour in Hip over-expressing tissue. I use isothermal titration calorimetry (ITC) to determine the binding affinity of Hip1 and Hip1R coiled-coil domains to different light chain isoforms. This will further characterize the different CLCs, and enable inhibition studies of the Hip-CLC interaction to investigate on the role of this interaction in metastatic cancer.

 
figure
 
Figure: This image shows clathrin cages of the neuronal light chain a clathrin variant. The samples were prepared by negative stain and imaged by transmission electron microscopy, the scale bar is 100nm.

 

 

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