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Written in sugar: Dr Rebeca Kawahara on bringing the glycan code into medicine
“It’s like a hidden layer of biology we’ve only just started to decode.”

Dr Rebeca Kawahara, a glycoproteomics researcher with dual affiliations at Griffith University’s Institute for Biomedicine and Glycomics and the Institute for Glyco-core Research (iGCORE) at Nagoya University, is working to decode one of biology’s most overlooked languages: the complex sugar structures, known as glycans, that coat every cell in the human body, shape how cells recognise one another, and may hold answers to some of medicine’s most persistent questions. Her journey from undergraduate proteomics to leading international glycome mapping initiatives spans three continents, several bold career pivots, and a growing conviction that the “glycan code” represents medicine’s next major frontier. Now at the centre of efforts to build a comprehensive atlas of human glycans, she is focused on making this hidden layer of biology readable and clinically meaningful for researchers worldwide.


Decoding the hidden language of cells

Rebeca’s work centres on something she calls the “glycan code” – the complex sugar structures, known as glycans, that attach to proteins and act as a kind of biological annotation system. Around half of all proteins in the human body are predicted to carry these attachments. Each cell presents its own unique glycan signature, shaped by multiple layers of regulation, from how genes are transcribed all the way through to how proteins are modified after they’re made.

That last step, post-translational modification, matters because a protein isn’t simply an inert structure once it exists. It can be switched on or off, directed to different parts of a cell, or made to interact with entirely different molecular partners, all depending on the modifications it carries. Glycosylation is one of the most widespread of these modifications, and yet it has historically been one of the hardest to study. Unlike DNA, glycans cannot be predicted from a genome sequence or amplified in a laboratory. Every measurement has to be made directly, from real biological samples, using highly sensitive and specialised techniques.

“It’s like a hidden layer of biology that we’ve only just started to decode,” Rebeca says. “I was fascinated by the idea that we might be missing a critical piece of the puzzle in understanding health and disease – that sense of uncovering something that’s been overlooked for so long.”

That difficulty is precisely what drew her in.

From gel to global initiative

Her entry into the field came through proteomics at a time when the technology was just beginning to mature. As an undergraduate, she joined a research group using mass spectrometry to explore the protein landscape of melanoma, and found herself captivated not just by the biology, but by the volume and resolution of information a single experiment could yield.

“I was immediately fascinated by the ability to generate large-scale biological data and, more importantly, to both identify and quantify hundreds of proteins in a single experiment,” she recalls. When researchers can measure hundreds of proteins simultaneously, patterns emerge that would otherwise be invisible: which proteins rise or fall together, which combinations are associated with a particular disease state, which shifts precede a change that might one day be detected in a blood test or a biopsy.

Photos by Kevin Chau at iGCORE, Nagoya University

That curiosity carried her into a PhD focused on discovering protein biomarkers in oral cancer. The practical stakes are straightforward: if you can identify a molecule that reliably signals the presence or progression of a cancer, you can potentially build a test around it: as an example, Rebeca envisions a saliva test during a routine dental visit, measuring a small panel of proteins known to be elevated in oral cancer, flagging a patient for further investigation before symptoms appear. “Potentially catching the disease much earlier,” she says, “when treatment is far more effective.” Her PhD work identified novel candidate biomarkers for oral cancer detection in patient saliva – work she’d later extend to prostate cancer in urine and colorectal cancer in blood plasma.

It was during this period that a pivotal realisation changed the direction of her career. Many of the proteins she was identifying as potential biomarkers were glycosylated, yet the proteomics methods she was using were largely blind to that fact. “I realised there was a missing layer of information that could be highly relevant to disease biology,” she says.

Supported by a FAPESP fellowship, she joined the lab of Prof Giuseppe Palmisano at the University of São Paulo for postdoctoral research in post-translational modifications, then spent a year at Macquarie University in Sydney, trained by glycoscience leaders Prof Morten Thaysen-Andersen and Prof Nicolle Packer. She subsequently secured an independent fellowship from the Cancer Institute NSW, during which one line of work crystallised what this field could actually deliver.

Working in colorectal cancer, Rebeca and her colleagues identified an enzyme called hexosaminidase B, which trims specific sugar structures on proteins and generates a distinctive glycan signature – short structures known as paucimannose glycans that are highly enriched in tumour cells compared to normal tissue.

What made the finding clinically significant was that the enzyme is not only present and active in tumours; it is also released into the bloodstream. That opened up a question: could its activity be measured in a simple blood test? Using a fluorescent assay, the team found that patients with higher levels of enzyme activity in their plasma had significantly poorer survival outcomes – roughly increasing up to twice the risk of death within five years compared to patients with lower levels.

When the enzyme was experimentally inhibited in colorectal cancer cells, the cells became less aggressive, showing reduced ability to migrate and invade – two of the hallmarks of cancer progression.

“It shows how understanding changes in sugar structures can translate into a real clinical tool – a blood-based prognostic marker – and at the same time point to a potential therapeutic target,” Rebeca says. “It’s a clear illustration that glycans are not just decorative modifications on proteins, but active players in disease that we can measure, understand, and potentially target.”

If you ask most people whether they’ve heard of DNA or the genome, the answer is almost always yes – largely thanks to landmark efforts like the Human Genome Project, which transformed our understanding of biology and medicine. The Human Glycome Atlas Project and the Human Glycoproteomics Initiative (HGI) aim to do something analogous for glycans: systematically mapping the glycan code at a scale that hasn’t previously been possible.

“In many ways, these efforts are laying the groundwork for the next major leap in life sciences, similar to what the genome project achieved years ago.”

But mapping something first requires being able to read it reliably and, in 2021, that was still an open problem. Under the HGI, Rebeca led a landmark study published in Nature Methods evaluating the different software tools and analytical strategies researchers use to identify glycopeptides, the fragments of glycosylated proteins measured in mass spectrometry experiments. Results varied substantially depending on which software was used and how the analysis was configured. By systematically comparing approaches and defining key parameters for more reliable analysis, the study provided practical guidance for the community and helped inform the development of better tools going forward.

“I realised how much impact we could have by making these approaches more accessible and reproducible,” Rebeca reflects. It made her see her work differently: not just as a source of new biological insights, but as infrastructure for others. Enabling non-specialist labs to confidently study the glycoproteome became as important a goal as the discoveries themselves.

The sex-specific glycoproteome

One of her most significant recent projects, developed at iGCORE and supported by the Human Glycome Atlas Project in Japan, involved mapping the glycoproteome across 19 different tissues in mice, comparing males and females across each of them.

Sex turned out to be a major driver of tissue-specific differences in glycan signatures, with pronounced variation in the salivary gland, liver, and kidney. The brain, by contrast, showed remarkable consistency between the sexes. Just as importantly, these differences arose from coordinated regulation of the glycosylation machinery itself, reflecting systematic biological differences rather than incidental variation.

Rebeca breaks it down:

“If glycans help cells communicate and respond to their environment, then men and women may be using slightly different ‘dialects’ of the same biological language across different organs.”

Biomedical research has long treated male and female biology as largely interchangeable, or considered sex differences only at a broad level. “From a genomic perspective, males and females differ by just one chromosome,” Rebeca notes. But at the level of the glycan code, the differences are widespread and systematic across many tissues, which means that biomarkers or treatments developed without accounting for sex could be missing important signals or be less effective for part of the population. “It reinforces the need to design research and medical strategies that take sex into account from the beginning – not as an afterthought. In the long term, this could lead to more precise diagnostics and more personalised treatments that better reflect the biology of each individual.”

Completing the study required integrating transcriptomics, proteomics, glycomics, and glycoproteomics into a coherent analysis – a task that demanded close collaboration with bioinformatics specialists and robust computational frameworks to ensure the different data types were genuinely comparable. “Without this level of computational support, much of the underlying biological complexity would have been extremely difficult to interpret.”

Learn more about the paper here.

In 2023, Rebeca was recruited to establish a dedicated Glycoproteomics Lab at iGCORE – a move that was, by any measure, a significant step. She was in Australia, approaching the end of an Early Career Fellowship, with a competitive grant application in progress and a stable research environment at Macquarie University. The offer from Japan arrived while the outcome of that application was still uncertain.

“It was a difficult decision,” she says. “Accepting the offer meant moving to a new country, adapting to a completely different culture, and taking my young family with me – my two boys were just one and four years old at the time.” The stability she had built felt real, and walking away from it felt like a genuine risk. In the end, she took the offer without knowing how things would unfold.

Photos by Kevin Chau at iGCORE, Nagoya University

“Looking back, it was one of the best decisions I’ve made. It pushed me out of my comfort zone, helped me grow in independence, and allowed me to build new international collaborations and expand my research profile. It wasn’t always easy, but that experience made me more resilient and more confident in my ability to take risks and create new opportunities.”

The experience also deepened something Rebeca has come to see as an underappreciated skill in science: the ability to work across cultures. Coordinating research between Japan, Australia, and Brazil meant learning, consciously, how different environments communicate, build trust, and make decisions. “In Australia, for example, communication tends to be quite direct and informal. In Japan, it is often more indirect and nuanced, with a stronger emphasis on building consensus and maintaining harmony.” What reads as efficiency in one context can read as bluntness in another. “Over time, I’ve learned to adapt; being more explicit when needed, more patient in consensus-building, and more intentional about building relationships.”

When it works well, she says, these collaborations become greater than the sum of their parts. “You’re not only combining expertise, but also diverse ways of thinking.”

Setting up the new lab also meant making deliberate choices about equipment and analytical infrastructure. For high-performance liquid chromatography, Rebeca sought out IonOpticks’ Aurora Series columns, which came well recommended by colleagues. “The performance has been outstanding,” Rebeca notes. Working with a Vanquish Neo coupled to an Orbitrap Exploris 240, the lab achieved sharp, reproducible chromatography – FWHM values under six seconds, stable across more than 500 runs.

“We were able to obtain excellent glycoproteome coverage, which was particularly important for our mouse tissue glycoproteome mapping studies.”

The frontier: one cell at a time

What keeps Rebeca up at night is the fact that, despite all the technical advancements in proteomics, “we are still not quite able to measure glycosylation at the single-cell level.”

The rapid development of single-cell proteomics, enabled by advances in automated cell sorting, next-generation chromatography, and increasingly sensitive mass spectrometry, is one of the most transformative shifts currently underway in her field. Instead of averaging a signal across millions of cells in a sample, researchers are beginning to measure individual cells directly. That matters because cells within the same tissue, even the same tumour, are not identical. The differences between them – not just in which genes they express, but in how their proteins are modified – may explain mechanisms of disease progression that bulk analysis has always obscured.

For glycoproteomics, this frontier is still just beyond reach:

“Glycosylation is so tightly regulated by the state of each individual cell,” Rebeca explains.” If we could truly map glycans at single-cell resolution, it would fundamentally transform our understanding of how individual cells generate their unique glycome and use it to communicate, interact, and function.”

If resources were no constraint, she would pursue exactly this: combining advanced cell sorting, multiplexed protein labelling, and comprehensive glycopeptide libraries to analyse hundreds or thousands of individual cells from cancer tissues directly. Alongside this, she would develop machine learning approaches to multi-omics integration: computational models trained on single-cell transcriptomic and proteomic data to predict glycosylation patterns at the single-cell level, linking gene expression, protein abundance, and glycan signatures within individual cells into a unified picture.

“This would allow us to capture cellular heterogeneity at an entirely new level,” she says, “revealing how glycosylation varies between individual cells within the same tumour and across diseases.” The downstream potential is substantial: more precise biomarkers, better understanding of how tumours evade the immune system, and more targeted therapeutic strategies.

Beyond the methods and the publications, Rebeca is reflective about what a scientific career actually asks of a person.

“A career in science is inherently uncertain,” she says,”and that’s not something to fear, but to embrace. There’s rarely a straight or predictable path. Instead, it’s shaped by unexpected opportunities, challenges, and the people you meet along the way.”

Her own path has taken her across three countries and several disciplines, each transition requiring a willingness to sit with not-knowing long enough to find out what comes next.

The advice she would offer her younger self reinforces this idea: “Don’t be afraid to explore and to pioneer. Some of the most meaningful opportunities come from following curiosity into the unknown. Those moments of uncertainty are often exactly what open new paths and lead to the most exciting discoveries.”

It’s the same instinct that drew her to glycans in the first place – the conviction that the most important things are often the ones nobody has thought to look for yet.

Detailed Q&A

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