Subcellular Ca2+ signalling microdomains regulating cardiomyocyte growth and function

This joint PhD project will be based at KU Leuven with a minimum 12 month stay at The University of Melbourne.

Project description
Precise control of intracellular Ca2+ levels is essential for heart function. Not only do increases in intracellular Ca2+ induce contraction of cardiomyocytes underlying the pumping of the heart, they participate in the regulation of gene expression that mediates long term adaptations such as hypertrophy and they modulate metabolism to ensure energy production matches demand.

Project aims

  • To develop probes for specific modulation and measurement of Ca2+ in cellular microdomains.
  • To measure Ca2+ changes in cellular microdomains at baseline and in response to cell stimuli that initiate pathological and physiological hypertrophic remodelling.
  • To test the influence of manipulation of Ca2+ in cellular microdomains on induction of transcriptional remodelling during the hypertrophic response to physiological and pathological stressors.
  • Model interactions between IGF/PI3K and InsP3 signaling pathways to determine how pathological and physiological hypertrophic stimuli modulate Ca2+ and downstream transcription factor dynamics to induce specific responses.

The question arises as to how Ca2+ can act in a selective manner to precisely control these diverse functions with great fidelity. Indeed, perturbation of Ca2+ regulatory mechanisms contributes to diminished Ca2+ transients and reduced cardiac contraction, arrhythmias and induction of pathological hypertrophic growth that ultimately can lead to heart failure or sudden cardiac death.

We will test the central hypothesis that the partitioning of Ca2+-dependent activities relies upon subcellular Ca2+ signalling microdomains that are coupled to their own specific Ca2+-dependent actions. Using state- of-the-art nanoscale imaging combined with a genetically-encoded toolkit of Ca2+ signal modulators and reporters to localise Ca2+ handling proteins and membranes we will quantify Ca2+ changes in subcellular microdomains including the nucleus, perinuclear space, dyad and bulk cytosol. Activation of gene expression will be determined using RNA-Seq, fluorescently-tagged transcription factors and reporters.

Known cues for pathological and physiological hypertrophy as well as strategies for artificially altering intracellular Ca2+ levels will be applied to allow identification of signatures and localisation of Ca2+ signals linked to specific functions. These data will be used to inform model development, with experiments guided by models generated during the course of this PhD project.

The project will be complemented by The University of Melbourne based project and the collaboration will ensure a successful completion of the project.

Supervision team:

Principal Investigators (PIs)

Professor Dr H. Llewelyn Roderick (KU Leuven)
Dr Vijay Rajagopal (The University of Melbourne)

Co-Principal Investigators (co-PIs)

Professor Edmund Crampin (The University of Melbourne)