Visualizing the DNA Damage Response in Purkinje Cells Using Cerebellar Organotypic Cultures

Our work is focused on understanding a human genetic disorder called ataxia-telangiectasia, or A-T for short. It is caused by loss of the protein kinase ATM. ATM has many functions and A-T is characterized by many symptoms, but the major symptom of A-T is progressive cerebellar degeneration and it is currently unclear which of the many functions of the ATM protein is the one whose loss is specifically responsible for this devastating symptom.

We're trying to investigate this central problem in A-T research and for this we are utilizing cerebellar organotypic cultures derived from wild-type and ATM-deficient mice. They allow us to focus on the cell type that is probably the first to be lost in the degenerating cerebellum of A-T patients, Purkinje cells. Like many fields in life sciences research in A-T leveraging a variety of advanced techniques and methods.

Those methods include animal models, novel types of tissue cultures, induced polyploid stem cells, cutting-edge imaging technologies, induced omic methods and single cell partials imaging. The source of cerebellar deterioration in A-T is deterioration of Purkinje cells. Those cells are notoriously difficult to isolate and cannot survive in cultures without supporting of other cell types.

A unique experimental challenge is obtaining mature, functioning human Purkinje cells using induced polyploid stem cell technology. Since growing isolated Purkinje cells is currently impossible, cerebellar organotypic cultures provide valuable opportunity to study those cells in a culture dish within the natural tissue context. Using protein correlation as a readout for DNA damage response is highly informative, particularly concerning Purkinje cells.

A major function of the ATM protein kinase is regulating the DNA damage response, which is critical for maintaining genome integrity and cellular homeostasis in the face of the ongoing DNA damage which occurs in every cell. We need to pinpoint the critical DNA lesion whose repair is defective in ATM-deficient Purkinje cells and we hope to do this using the cerebellar organotypic cultures. This should allow us to understand better the physiological and molecular basis of the most important and devastating symptom of A-T, the cerebellar degeneration.