Immune health maintained by meticulously ordered DNA

15 October 2018
Walter and Eliza Hall Institute researchers have revealed how immune health is maintained by the exquisite organisation skills of a protein called Pax5.

The new study published today in Nature Immunology shows how Pax5 helps to efficiently organise the genetic information (DNA) required for our immune cells to maintain their form, function and help fight disease. The findings also suggest that a breakdown in this process of organisation by Pax5 could increase the risk of diseases such cancer.

(L-R) Professor Gordon Smyth, Professor Stephen Nutt,
Dr Tim Johanson, Dr Hannah Coughlan and Dr Rhys Allan.

The research was led by Dr Rhys Allan and Dr Tim Johanson, in collaboration with Professor Stephen Nutt and bioinformaticians Professor Gordon Smyth and Dr Hannah Coughlan from the Walter and Eliza Hall Institute of Medical Research.

At a glance

•    Researchers have discovered that a protein called Pax5 helps to meticulously organise DNA in immune B cells.
•    Carefully organised DNA means cells can easily access the genetic instructions required to maintain specific functions to keep the body healthy.
•    The findings also show how Pax5 could help the immune system guard against diseases like cancer.

The importance of maintaining order

Dr Johanson said the researchers had shown, for the first time, that Pax5 could sweep across the genome and fold, twist and store DNA for B cells in a fantastically ordered way – making each cell into what is like a jam-packed but very neat suitcase.

“This immaculate organisation is crucial because each cell contains roughly two meters of DNA – that’s a huge amount of material to fit inside something smaller than a grain of sand.

“Every second of every day, different cells require access to highly specific parts of DNA in order to perform a myriad of jobs that help keep us healthy,” he said.

Dr Johanson said life depended on cells accessing what they needed, when they needed it.

“For instance, immune B cells must access the right information to produce potentially life-saving antibodies that are critical for vaccine and immune responses.

“Think of how a meticulously ordered suitcase increases your chance of finding a specific item of clothing at a moment’s notice, and, how a jumbled case could work against you finding what you need. In the case of our bodies, the difference between order and disorder can be a matter of life and death,” he said.

Disorder leads to disease

Dr Allan said the disarray of DNA could lead to errors ‘further down the line’.

“Seemingly small errors in the process of DNA organisation can turn out to be very serious drivers for disease.

“A lack of instructions required to function can put cells at risk of morphing or devolving into something they perhaps shouldn’t be – like a cancer cell. It is therefore unsurprising that Pax5 is faulty in many childhood leukaemias.”

The power of computing

DNA being ordered by the transcription factor Pax5.
WEHI.TV image by biomedical animator Ms Etsuko Uno.

Dr Coughlan said recent technological advances had allowed the teams to visualise Pax5’s activity across the genome for the first time.

“With the help of powerful computers, we performed thousands of complex calculations to spot the difference in DNA organisation when Pax5 was present, versus absent, from the B cells. Our analyses showed that without Pax5, the cells could no longer package their DNA adequately.

Bioinformatics is shining a light on how vital factors regulate our DNA. This in turn progresses an understanding of what could be going wrong in cases of disease,” she said.

Two roles for the same player

Dr Allan said the findings were particularly intriguing because for two decades Pax5 was known only as a ‘transcription factor’.

“Transcription factors help cells identify the instructions they need, but there was no evidence they could also play a part in the organisation and upkeep of this information, until now,” he said.

The research was supported by the Australian National Health and Medical Research Council, the Australian Research Council, the Victorian State Government and the Australian Government’s NHMRC Independent Research Institute Infrastructure Support scheme.

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