Our research focuses on two main areas:
The role of p38α-TAB1 interaction
The alpha isoform of p38 mitogen-activated protein kinase (p38α) is expressed in all cells and involved in multiple stress-sensing pathways. We are interested in an unusual form of p38α activation that was described in the heart during ischemia in the laboratory of Professor Michael Marber. During ischemia p38α activation is through autophosphorylation promoted by a scaffold protein known as TAB1. We have previously solved, using NMR and X-ray crystallography, the structure of the complex between p38α and TAB1. The structure has revealed at atomic resolution how TAB1 interaction induces p38α auto-activation, it also showed that the binding surface used for the interaction between the two proteins is conserved across species. This evidence suggests a role for the interaction that goes beyond the heart and ischemia. Recent data in the literature have shown that p38α-TAB1 interaction modulates the senescence phenotype in T-cells and it is involved in the regulation of several E3 ubiquitin ligases.
In order to characterise the biological role of p38α-TAB1 interaction we have created a knock-in mouse where the interaction between the two proteins is selectively abolished by mutating four key residues on TAB1 that are responsible for p38α-TAB1 recognition.
1) Biological characterization of p38α-TAB1 interaction. To start we plan to use the knock-in mouse model as a tool to better investigate the role of the interaction in the ubiquitination pathway and the senescence phenotype.
2) We are looking for small molecules that could inhibit the interaction between the two proteins, to this end we are using isothermal calorimetry, NMR spectrometry and X-ray crystallography.
VIDEO legend: The video shows the structural changes in p38α induced by TAB1 binding, that lead to p38α autophosphorylation
Lamin b1 is a p38α substrate
Lamin b1 is a filament protein that forms part of the nuclear lamina, a structure at the inner side of the nuclear membrane which contributes to nuclear envelope integrity, regulates chromatin organization, and transcriptional activity.
Using a proteomic approach we have identified lamin b1, as a substrate of p38α, the residues phosphorylated by the kinase are in the C-terminal region of lamin b1. We also observe localization of p38α in the nucleus upon simulated ischemia in adult rat ventricular cardiomyocytes.
1) Biophysical characterization of the C-terminus region of lamin B1. We want to study the structural changes of lamin b1 induced by phosphorylation.
2) Analyse the downstream effect of p38α mediated phosphorylation of lamin B1 on the cardiovascular system