AsianScientist (Feb. 9, 2016) – For scientists trained within the last decade, tools such as polymerase chain reaction (PCR) thermocyclers may seem mundane, found on top of every lab bench and considered as little more than sophisticated water baths. However, the ubiquity of these tools belies the biomedical revolution they have enabled. The ability to produce many copies of DNA, and the technology to translate them into proteins, have spawned countless innovations and made biomedical science the significant field that it is today.
While this may be true for DNA and proteins, the same cannot be said of another important class of organic molecules: carbohydrates, also known as saccharides or sugars. While making many homogenous copies of DNA is a matter of a few hours in a PCR thermocycler, synthesizing carbohydrates is a complex task that could take several weeks or even months, and results in a mixture of different isomers called glycoforms.
Recognizing the important role that saccharides play in human health and disease, Professor Wong Chi-Huey, president of Taiwan’s Academia Sinica, has built his scientific career around pioneering new means of manipulating saccharides and applying those methods to challenging problems such as infectious disease and vaccine development.
“I was first drawn to the field of glycobiology as it was the least understood area,” Wong shared with Asian Scientist Magazine. “There have not been equivalent tools like PCR or sequencing, creating a huge research bottleneck.”
The complexity of carbohydrates
Glycosylation, the enzymatic attachment of carbohydrates, is one of the most common and biologically important post- translational modifications that proteins undergo after they are synthesized. More than 50 percent of all proteins made in the body are glycosylated, a process which can modify their structure and function. For example, glycosylation is required for the proper folding of some proteins and can influence protein-protein interactions in others.
Genetic defects in the glycosylation pathway can lead to severe disease, particularly affecting the nervous system and muscles. However, pinpointing the underlying cause can be challenging, as the glycosylation pathway involves more than a hundred different enzymes, ranging from glycosyltranserases and glycosidases to transporters and synthases.
To add to the complexity, there are nine monosaccharides (e.g. glucose and fructose) commonly found in biological systems, with at least three different ways of forming linkages between each monomer. In contrast, there are only four nucleotides (A, T, G and C) used in DNA, with only one type of chemical bond linking the monomers. Therefore, forming a short chain of four monosaccharides results in 15 million possible combinations, Wong explained, whereas a chain of four nucleotides involves only 256 (44) possible combinations.
Understandably, this complexity makes the large-scale synthesis of saccharides very challenging. Traditional oligosaccharide synthesis involved multiple steps of chemical manipulation, with the need to purify intermediates at each step. Not only was the process very complicated and time- consuming, taking up to several months, it was also inefficient, giving poor yields.
Dissatisfied with this slow and laborious process, Wong and his research group set about to developing a more efficient and reliable way of synthesizing saccharides.
What they came up with was Optimer One-Pot Synthesis (OPopS), an enzymatic method that facilitates the synthesis of oligosaccharides.
“It is the first automated chemical synthesis of oligosaccharides, enabling rapid access to oligosaccharides for discovery research,” said Wong.
The method is based onthe fact that the addition of different donors called glycosyls affects the reactivity of each monomer.
“Using this fact, we were able to tune the reactivity of the monomeric building blocks. We then compared the reactivity of the monomers and compiled a large database documenting the relative reactivity values of each monomer,” Wong said.
“Ian Ollmann, a very bright student in my lab who subsequently left academic research and went to develop computer systems for Apple, wrote an algorithm that could be used to rank to suitability of donor molecules. This allows researchers to perform sequential coupling in a one-pot reaction, where the product can be obtained after a few minutes or hours, as opposed to months with traditional methods.”
“The development of programmable and enzymatic synthesis of oligosaccharides and glycoproteins has undoubtedly facilitated our understanding of the role of carbohydrates in biology, not only in my own research group, but for the whole community of glycobiologists,” said Wong.
From cancer vaccines to sugar arrays
The ability to synthesize oligosaccharides easily and quickly enabled has already led to successful applications such as a vaccine for cancer.
“Without exception, the oligosaccharides sialic acid and fucose are highly expressed in cancer cells, making them natural targets for the next phase of our study. We were interested in how these oligosaccharides are incorporated into glycoproteins, and what effect this had on the progression of cancer, if any,” Wong explained.
In order to study the effects of sialic acid and fucose in cancer, Wong and his group synthesized the sugars and linked them to fluorescent molecules, allowing them to act as molecular probes. When these synthetic sugars were fed to cancer cells, they eventually found their way to the cell surface proteins, which were subsequently identified by mass spectrometry. One of the proteins identified in this way was Globo H, which is found only on cancer cells and not on healthy cells.
Based on this discovery, Wong was able to develop one of the first carbohydrate- based vaccines, Globo H conjugated to a carrier protein. Crucially, Globo H is found not only on mature cancer cells, but also on cancer stem cells. This means that the vaccine, currently in Phase III trials, could potentially eradicate cancer at its source.
Easily available synthetic oligosaccharides also facilitated the development of the next useful tool that Wong invented, the sugar array. Microarray technology has allowed the high throughput discovery of drugs that can bind to DNA and uncovered differences in RNA expression patterns, but was not available for studies using saccharides.
“By spotting the synthetic oligosaccharides on glass slides coated with active esters to form covalent linkages, we were able to create the first microarrays for carbohydrates,” Wong said.
“These microarrays could be used to study sugar-protein interactions commonly found on the surface of cells. It is a useful and much-needed tool for the understanding of specificity and multivalent interactions between sugars and proteins.”
In the context of cancer, sugar arrays could be used to detect antibodies against cancer-specific sugars such as Globo H. Able to detect as few as ten molecules of antibody in a single cubic centimeter of fluid, sugar arrays could be useful in the early stage diagnosis of cancer and also to monitor the response to vaccination.
Life at the Academy
The discoveries made over the course of his 30-year long career are based on research conducted in labs at the Scripps Research Institute in the US, where he was the Ernest W. Hahn Chair from 1989 to 2006; to RIKEN in Japan, where he directed the Frontier Research Program on Glycotechnology between 1991 and 1999; and of course at Academia Sinica in his native Taiwan, where he was elected as academician in 1994 and has served as president since 2006.
“My election as president came as a bit of a surprise to me, as I had never been in an administrative position. But, encouraged by the former president Lee Yuen Tseh and many other academicians, I decided to accept the position and have since tried my best to do a good job,” he shared.
“As president of Academia Sinica, I have three main responsibilities. Firstly, of course, is the budget; I have to explain the budget of the Academy to the congress. Secondly, I am involved in the appointment of institute directors for the 24 institutes and seven centers under Academia Sinica. Lastly, I play a role in deciding the major direction of the Academy.”
Wong’s commitment to the work of the Academy has by no means resulted in his research career has taking a back seat.
“We have a special feature here at Academia Sinica. In most national academies, the head is usually not involved in research or not even a scientist. But here, I am an active scientist. Even though I serve as the president I still have research going on,” Wong said.
“You may ask how I find time for that. At our institution, we have a really good administration office. The person in charge of administration is equivalent to the chief operating officer, with a team of 300 people assisting him. There are also three vice-presidents to take care of the three divisions individually, namely, the Divisions of Humanities and Social Sciences, Mathematics and Physical Sciences, and Life Sciences.”
Transition and translation
“Taiwan is in a transition from the information and communication technology area to six other emergent industries as prioritized by the government: biotech, healthcare, clean energy, agriculture, tourism and culture,” Wong said.
“If you look at these six emerging industries, three of them are directly related to biotech. Green energy is indirectly related, for example biofuels and solar energy could also be in the biotech category. So I think biotech is quite important to Taiwan as the next emerging industry.”
However, even as Taiwan forges ahead in biotech, the sector faces the pressing issue of brain drain. With the majority of high school students going on to earn college degrees, Taiwan has a well-qualified workforce that has gained the attention of its regional neighbors. In 2011, Wong and others issued a declaration highlighting the problem to the Taiwanese government.
“Our neighbors including Singapore, Hong Kong, China and Korea are moving very fast. They improved their salary, and their governments have committed substantial funding to research. We have started to see that they are coming to Taiwan to recruit talent,” Wong said.
“I don’t see that as negative; I see it as an opportunity for us to think about how to retain our good people. The government has become quite concerned about the brain drain, and has taken action such as improving salaries and allowing scientists to do part time work with other institutions and the business sector. I think that’s a good sign, we are beginning to face the problem.”
Wong has also noticed that while countries in Asia such as Taiwan are strong in early stage drug discovery and late stage trials, there is a gap in the middle translational phases.
“In general, there seems to be less appreciation of the importance of basic research and its translation to innovative development in Asia. I would say that this is one of the biggest obstacles to research and development in the region. I think there is much that the national academies such as Academia Sinica can do to bridge the gap between academia and industry.”
Wong points to the Science and Technology Act and the New Pharmaceutical Development Act as practical measures the Academy has taken to bridge the gap between fundamental and applied research. These two bylaws, analogous to the Bayh-Dole Act in the US, encourage investors to get involved in the biotech sector.
“We recognized that the biotech industry is risky, and that we needed to have a bylaw to encourage investments. Incentives include tax benefits for investment and allowance for scientists or inventors to become consultants or board members and hold to technology shares.”
“As a result of these laws, Taiwan now has more than 20 new drugs in Phase III clinical trials. The market capitalization of the biotech sector is now about US$30 billion, or one trillion Taiwan dollars. I think the government, if they do it right and keep the focus on improving the bylaw regulation and the research environment, they will give the people a lot of encouragement. Taiwanese are very innovative; I believe they will perform very well in the right environment,” Wong stressed.
Science in society
In his position as scientific advisor to the government of Taiwan, Wong has had the opportunity to guide policy decisions, in addition to writing new laws. However, he strongly feels that making an impact on society is something that all scientists should strive to do, not just the president of the national science academy.
“Science is evidence-based and apolitical, and thus the opinions of scientists are often respected. In addition toconducting good research, scientists also need to demonstrate their social responsibility by translating their discoveries for the benefit of society and to encourage more people to join the public service,” Wong said.
As science policy in Asia continues to develop and evolve, Wong feels that it is an exciting opportunity for scientists to get involved in and have a say in the process and the final outcome.
“I think science could make the whole region work together more smoothly and peacefully. We can work together to attack major problems in Asia, such as infectious disease, agriculture, food supply, population, energy and environmental issues,” Wong concluded.
This article was first published in the print version of Asian Scientist Magazine, October 2014.
Photo: Wong Chi-Huey/Academia Sinica.
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