Mediating the delicate balance between protection and damage

The Opening Session theme on how the disease progresses within the Central Nervous System (CNS) continued with the presentation by Prof Stan Appel from Baylor College of Medicine, Huston on neuroinflammation.

Examination of post-mortem brain and spinal cords from people with MND shows clear evidence of inflammation (although Prof Appel was quick to point out that this is not the same as occurs in ‘primary’ inflammatory conditions such as multiple sclerosis). Similar patterns are seen in human MND spinal cord and in SOD1 mice, suggesting that at least for this aspect of the disease, SOD1 mice may be a good model of human MND.

He went on to explain how migroglia, the ‘innate’ immune cells of the CNS, help mediate a delicate balance between protection and damage. The speed of progression in MND appears to be dictated by this balance.

Prof Appel showed that SOD1 mice exhibit two phases of disease: an early slow phase, where the microglia release a series of protective factors, and a rapid secondary progressive phase where levels of these protective markers fall and are replaced by a rise in ‘pro-inflammatory’ toxic factors. Of course, strains of lab mice are so inbred that they are genetically very similar and develop the disease in a uniform manner. Humans on the other hand are very different, as is the way the disease progresses between one individual and the next, so the two stages of disease are not easy to demonstrate in MND patients. However, by examining the inflammatory factors present in patients with very rapid progression against those with slower progression, he was able to show that the factors associated with the second ‘rapid progression’ phase in mice were also present in the rapidly progressing patients. He suggested that this may assist clinicians in predicting how the disease is likely to progress in patients at an early stage in the disease.

It is relatively easy in cell culture studies to tilt this balance from protective to toxic, but could the balance be tilted the other way in patients, as a therapeutic strategy? Certainly, in response to a question from the floor, he suggested that greater attempts should be made in this direction, commenting, “The whole issue of immunosuppressant drugs in MND needs to be re-opened. But – you can’t just take down all immune responses in an uncontrolled way. You need drugs that are much more selective”.

Read our official day one symposium press release on our website.

Copying, transporting and creating proteins – what could possibly go wrong?

Proteins are the building blocks of our cells and have a variety of important roles within our bodies. The instructions for how to build our proteins sit within our DNA, our genetic code in the control centre of our cells (the nucleus). There are many steps to go through from reading that ‘raw’ instruction to ending up with a fully functioning protein.
However, the amount of information held within our genetic code is so huge that only small segments of it are read and transferred to the factory floor, as and when they are needed. These copies, known as messenger RNA, are small enough to be transported to the ‘factory floor’ of the cell to large machine-like entities called ribosomes where the copy is read, and used to create the resulting protein.
When I was doing my A levels and later at University (yes, that long ago!), we were taught that only 1% of the genetic code ever made it to the factory floor. This held true until a couple of years ago. However, as explained by Professor Bob Brown in his presentation at the ‘RNA and protein processing’ session this afternoon, such is the change in our knowledge in that area, we now know that 95% of our genetic code makes it through to the first step of making proteins.
This was a key piece of context in trying to understand the role that TDP43 plays in functioning cells – never mind specifically in motor neurones or in cases of the presence of damaged TDP43 in MND!
Professor Brown, University of Massachusetts Medical School, Boston, USA went on to give an enlightening review of what has been uncovered about this fascinating protein (TDP43) so far. Once the protein of TDP43 has been correctly made, its function is to go back and ensure that other proteins are correctly made too – the so called ‘reading helpers’ of the cells, or ‘editors of instructions’. Another new fact to me from this talk was that TDP43 is involved in editing or reading up to ONE THIRD of all proteins within the cell. That’s a city fat cat type of job! So how is it all related to it’s function in MND?
Some elegant experiments have shown that TDP43 regulates how many copies of it’s own protein are made. However, the regulation takes place in the control centre of the cell (see the top of this blog). If TDP43 gets stuck or waylaid on the factory floor, it can’t get back to press the stop button in time. So it’s thought that more and more protein is made, accumulating on the factory floor until that accumulation can be seen as the protein deposits so characteristic of what you see of motor neurones affected by MND down the microscope.
Part of the editing work that TDP43 does so well is known as ‘splicing’. In true ‘Blue Peter’ style, here is a description of that process that Kelly prepared before I flew out to Sydney:

Alternative protein
One gene can hold the instructions for a number of different versions or variants of a protein. These variants are created when different parts of the gene are used in alternative combinations. This is a normal process and it’s called ‘alternative splicing’. This complicates matters in terms of genetic research, as even though we have approximately 20,000 genes, we could potentially have a much higher number of functional proteins because of alternative spliced variants.

How does alternative splicing work?
The picture (below) depicts a simple version of how a gene can be alternatively spliced, given three ‘parts’. The example demonstrates that the first version of the protein is made up of parts 1, 2 and 3, whereas version two is made up of only parts 1 and 3. These resulting proteins would go on to function in our bodies in potentially different ways. It is therefore possible for a number of different proteins to be created given one set of original instructions in the genetic code.

 

 

Read our official day one symposium press release on our website.

Deserved recognition

At the end of the opening session of the International Symposium on ALS/MND, two members of the MND research community were recognised for their contribution to the field.

Professor Orla Hardiman, from Trinity College, Dublin is this year’s recipient of the Forbes Norris Award. Presented by Dee Forbes Norris, this award recognises care and compassion in the study and management of MND/ALS. It is awarded by the International Alliance of the ALS/MND in consultation with the World Federation of Neurology. Prof Hardiman accepted the award saying “I’m not normally lost for words, but to use a local expression, I’m gobsmacked”. She paid tribute to her colleagues throughout her career and in particular to what she described as as her formative years in Boston, USA, working with Professor Bob Brown Jnr.

It was a privilege to witness the first presentation of an Institute Paulo Gontijo (IPG) Young Investigator award at the Symposium. Following a moving speech from Paulo’s daughter Marcela, Professor Mamede de Carvalho, chair of the awarding panel announced that the unanimous decision was to give the award to Dr Aaron Gitler of University of Pennsylvania.

http://www.ipg.org.br/noticia.php?id=319&lang=1

“I’m honoured and humbled to accept this award” commented Dr Gitler. “The ALS field is experiencing a revolution, with paradigm changing discoveries even in the last few months – it is good to be a part of it”.

He gave a brief overview of the research that led to this award. The work has been conducted in the most basic of organisms – yeast. Without a brain and spinal cord, looking at yeast may seem an unusual way to study MND Dr Gitler acknowledged. However, as his talk demonstrated, yeast are an excellent model for understanding a common cellular sign of many neurodegenerative diseases – accumulation of proteins. A modifier of protein that accumulates in the yeast model led the way to identifying a link with a protein called Ataxin2 in MND.

Read our official day one symposium press release on our website.

Rip roaring start to Symposium

Entering the room for the opening session of the International Symposium on ALS, there was a real air or anticipation. Organisers (yes, that included you, Brian!) nervously pacing back and forwards, checking final details and greeting old friends and colleagues. Then Wim Robberecht, chair of the Programme Committee, called us all to order. A ripple of murmuring and camera flashes from the back of the room drew our attention as Glen Doyle on behalf of the Gadigal tribe welcomed us to Sydney by playing the didgeridoo and singing us a welcome song. Dressed and decorated in a traditional manner it was a stunning start to the meeting!

We heed the invitation of the President of MND Australia, Ralph Warren, to learn and participate in the deliberations, by absorbing the excellent talks of the two opening speakers. (Yes, there was a third presentation too, but more of this later).

Prof Ravits gave us an insight into what may be causing the differences that we see in people with MND. As he said himself, he started his talk in the most fitting way – by starting with one of his patients, describing their symptoms over the progression of their illness. Even for people with the form of MND known as ALS (or amyotrophic lateral sclerosis) each person develops the disease in a different way – why?? Prof Ravits has identified a broad two stages of disease – an early stage, where the symptoms are separate and very specific and a later stage where there is generalised damage to motor neurones and a broader range of symptoms. On a cellular level, these symptoms are reflected in ‘trigger’, ‘propagation’ and ‘neurone death’ stages of disease. Learning more about the early stage of the disease may give us opportunities to target specific treatments to the area of motor neurone damage, he concluded.

The theme of a trigger for motor neurone damage dovetailed the presentations of John Ravits and the next speaker, Garth Nicholson together. In a spectacular video involving a chain reaction of ping pong balls being released from a large table of loaded rat traps, Prof Nicholson highlighted that a trigger event is needed in all forms of MND –whether it is the rare, inherited form of MND or the more common sporadic disease. In the video, this trigger was a colleague throwing a single ping pong ball on to the table, triggering all of the other balls to be released and fly everywhere (with the initiator cowering in the back of the room to protect himself from the flying balls!). He is optimistic for the future of MND research in finding these, as yet unknown triggers of disease.

Read our official day 1 press release on our website.

Tuesday evening – the night before Symposium

At 6pm this evening, there was a real air of anticipation at the conference hotel. On level 2 the poster presenters were gradually finding their allocated slots and gaps were being filled. Up the escalator on level 3, the registration desk has now closed for the night. It will open again at 6am in the morning, ready to register another few hundred delegates. The lanyards are neatly rolled, the bags stacked tidy and ready for their eager recipients. A snake of coffee cups is ready for that all-important mid-morning energy boost.

Getting into the lift is like entering a who’s who of the MND world, international scientists and clinicians greeting each other and exchanging stories on jet lag, holiday plans and of course the results from their lab or scientific gossip.

As well as soaking up this atmosphere, today I’ve been busy putting Kate and Kelly’s plans for the poster session into action. The poster session is arguably the most interactive part of the meeting, an opportunity to share a hard copy of your presentation with a (possible) 600 people is valuable. They may pass on the next tips to helping get that experiment to work or you may set up a new collaboration or redirect your research. However, in order for this all to happen, 300-ish 2m high and 1m wide boards, need to be individually assigned to specific posters, in an order that (I hope) the delegates will follow. Thanks to Harriet for all her help with sorting this out.

Across the road from the hotel is the Queen Victoria Building shopping arcade. It is beautifully decorated for Christmas – there are only a few weeks to go. But for Symposium delegates it is only one more sleep before our excitement begins!

Another recycling bounty hunter linked to MND

In the short space of three months, details of a second gene have been published linking MND to the protein recycling system in our cells.

Leading this research was Prof Teepu Siddique, eminent MND researcher from North Western University in Chicago USA. Not only was he the founder of the first MND causing gene SOD1, but he also led the group that identified faults in the UBQLN2 gene in MND in August 2011. This research was published in the November edition of the Archives of Neurology journal.

We’ve invited Prof Siddique to give a plenary talk at this year’s International Symposium in Sydney, Australia from 30 November to 2 December 2011, at which we believe he’ll be discussing these exciting new advances!

What did they do?
Instead of searching for common genetic mistakes in families with the inherited form of MND, this research group focused on a candidate gene called SQSTM1. They chose SQSTM1 as a candidate due to the prior knowledge that its protein product is associated with MND.

They then unravelled the code for this particular gene in 340 people with the rare, inherited form of the disease and 206 sporadic cases of MND. They also compared these with 738 healthy controls.

They identified 10 different mistakes in the SQSTM1 gene in 15 people and did not find any of these mistakes in the healthy controls. The research group therefore estimate that genetic mistakes in the SQSTM1 gene could account for approximately 2-3% of cases of MND.

However, it is not yet conclusively known whether these mistakes cause MND, or increase the risk of somebody developing the disease. Further studies are therefore needed to confirm this.

What does SQSTM1 do?
The gene SQSTM1, holds the instructions for a protein called P62, otherwise known as sequestosome 1. 

The P62 protein can be thought of as a ‘bounty hunter’ of proteins that need to be recycled inside motor neurones and other cells. When given instructions to find proteins waiting to be recycled, it seeks them out and delivers them to the cells recycling system.

P62 has a related role to ubiquilin 2 (UBQLN2 which we wrote about in August) as they both work in the protein recycling system within the body.

This research therefore further implicates that the protein recycling system is faulty in MND.

The next steps with this story, is for researchers to confirm whether mistakes in the SQSTM1 gene cause, or contribute to the disease in other populations around the world. They will also need to investigate how the protein recycling system can go wrong in MND to be able to develop new treatments that can target these processes to slow down, or stop the disease.

More information on the protein recycling system:
Last month, Prof John Mayer from University of Nottingham, who is the Chair of our Biomedical Research Advisory Panel, took us behind the scenes of the protein recycling system on our research blog

Read our press release.

Reference: Fecto F et al. Arch Neurol. 2011; 68(11):1-7