Center/Research Area Affiliations
Dr. Pablo Argüeso earned his PhD in Biochemistry from the University of Valladolid in Spain. He completed a postdoctoral fellowship at Schepens Eye Reserach Institute of Mass. Eye and Ear after working briefly at the Institute for Cancer Research at The Norwegian Radium Hospital in Oslo. He conducts research in the fields of glycobiology and ophthalmology, focusing on the structure and function of mucins—highly O-glycosylated, high-molecular-weight glycoproteins that constitute a major component of the protective biofilm on epithelial and endothelial cell surfaces. More recent research from his laboratory seeks to define the role of carbohydrate interactions on the physiological and pathological remodeling processes associated with wound repair. Dr. Argüeso has published more than 60 peer-reviewed manuscripts and book chapters in such journals as the Journal of Biological Chemistry and the Journal of Cell Science and Nature Communications. He participates in a number of grant review panels, currently serving as a standing member of the Biology of the Visual System study section for the National Institutes of Health, and contributes to both national and international scientific societies, having chaired the program committee (cornea section) for the Association for Research in Vision and Ophthalmology (ARVO). As a faculty member, he has obtained independent funding for his research programs from different sources, including the NIH, corporate entities, and nonprofit organizations. R01-Research Project Grants from the National Eye Institute have funded his laboratory since 2003. He is currently the principal investigator for the P30 Core Grant for Vision Research and director of the Morphology core at Schepens Eye Research Institute of Mass. Eye and Ear.
Download his CV [PDF] for more information.
B.S., Chemistry, University of Valladolid, Spain (1993)
Ph.D., Biochemistry, University of Valladolid, Spain (1997)
Research Fellowship, Institute for Cancer Research, Department of Biochemistry, the Norwegian Radium Hospital, Oslo, Norway (1997)
Research Fellowship, Schepens Eye Research Institute of Mass. Eye and Ear (1998-2002)
2015-2021 Member Center for Scientific Review, National Institutes of Health
2015: Silver Fellow The Association for Research in Vision and Ophthalmology
2014: Excellence in Tutoring Academy Center for Teaching and Learning, Harvard Medical School
2013: Alice J. Adler Fellowship Harvard Fellowships for Scholars in Medicine
2004: Young Investigator Award The International Society for Eye Research
2003: Young Investigator Award Tear Film and Ocular Surface Society
1998-99: Distinguished Collaborator University of Valladolid, Valladolid, Spain
1997: Apto cum laude (PhD) Department of Biochemistry, University of Valladolid, Spain
Dr. Pablo Argüeso's research focuses on one of the last frontiers of molecular biology—glycobiology—analyzing the sugars that coat the surface of the eye and deciphering their role in protecting the eye against dehydration and pathogen invasion.
What is glycobiology?
“Glyco” derives from the Greek word "glykos”—meaning “sweet”—and refers to sugars or carbohydrates. The term glycobiology was originally coined in 1988 and recognizes the discipline of biology that studies the structure and function of the carbohydrate chains (also called glycans) present in all living organisms. In humans, there are 10 major sugar molecules that combine in multiple conformations among themselves, and then with proteins and fats, to create a vast array of glycoconjugates that help determine the fate of our cells. Unlike the case with the genetic code, there is no a universal code that predicts the structure of each carbohydrate chain and, therefore, the study of glycans has lagged far behind those of other major classes of biological polymers.
Carbohydrates (colored spheres in figure) are attached to the cell surface by different proteins (ribbons). Mucin carbohydrates extend far away from the cell membrane and act as a protective layer that senses the external milieu. Underneath the mucin barrier, and close to the cell membrane, there are smaller glycoconjugates that participate in the normal functioning of the cell.
Glycobiology is one of the most rapidly expanding fields in the biomedical sciences. Why?
Carbohydrates have been traditionally considered only as sources of energy for the living organism. However, during the last few years, it has become evident that carbohydrates also play important roles in determining cell function. The large number and variety of carbohydrate chains that are located on cell surfaces modulate a wide variety of cell-cell and cell-pathogen interactions. This communication results in a varied spectrum of cellular events, such as the secretion of bioactive substances, recruitment of immune cells into areas of cellular damage, and cancer cell metastasis.
Recent progress in the field of glycobiology is being facilitated by the development of new methodologies for the high-throughput analysis of glycans—a type of study known as glycomics. In 2001, the NIH’s National Institute of General Medical Sciences awarded a $34 million grant to form the Consortium for Functional Glycomics, whose goal is to develop and disseminate resources to researchers who are defining the paradigms by which carbohydrates function in cellular communication. As a result, the discipline of glycobiology is growing exponentially, with an increasing number of investigators entering the field, as well as biotech and pharmaceutical companies investing in it.
Can glycomics be applied to the study of the surface of the eye?
Similarly to other mucosal surfaces, such as the gastrointestinal tract or the mouth, the ocular surface contains large amounts of the molecules known as membrane-associated mucins. Due to their extremely large size, they extend far away from the cell surface, forming a protective barrier (see figure) that is thought to prevent desiccation and to protect the eye against infection resulting from its continuous exposure to pathogenic microorganisms. Historically, it has been very difficult to analyze these molecules because they are heavily glycosylated—up to 60% of a mucin molecule’s mass is sugars, while the remainder is protein. Glycomics has provided the technology necessary to analyze the fine structure of these molecules and to test different hypotheses about their protective function.
What is known about the glycan composition of mucins on the ocular surface?
Data from our laboratory have shown that the glycan structure of mucins at the ocular surface is different from that at other human mucosal surfaces. This difference may reflect specific requirements of the eye. In this regard, ocular mucins seem to have unique carbohydrate arrangements and modifications at the end of the glycan chain (red spheres in the Figure). These unique structures, which are in close proximity to the external milieu, may represent a defense mechanism, in that pathogens surveying the surface of the eye would encounter these atypical glycans rather than binding receptors that would allow colonization. This is a hypothesis that we are currently testing in the laboratory.
Are carbohydrates altered in ocular surface disease?
Yes. In patients with dry eye—a disease that affects 10 to 15% of middle-aged and older Americans—there is an alteration in the enzymatic machinery used by the cell to add a sugar known as N-acetylgalactosamine to mucins. Since carbohydrates are specialized molecules that retain water, we have hypothesized that their relative absence in dry-eye patients may contribute to the desiccation of the ocular surface. Interestingly, in these patients, there is an initial attempt by the eye to produce more of the required enzyme and, therefore, to add more N-acetylgalactosamine to mucins, but the battle is lost as the levels of enzyme decrease and the ocular surface dries out.
We are currently using high-throughput technology to obtain a more detailed picture of the glycosylation changes that occur with ocular surface disorders. This is being performed using microarrays—provided by the Consortium for Functional Glycomics—that will monitor the expression of approximately 2,000 human genes relevant to carbohydrate biology.
Can diseases be treated with therapies based on carbohydrate technology?
Yes. An example is “congenital disorder of glycosylation type Ib,” in which the defective synthesis of glycans causes gastrointestinal disorders and, in some instances, life-threatening bleeding. This disorder is currently treated with oral administration of mannose, the particular sugar that is lacking in this disease. In another application, pharmaceutical companies are attaching glycans to drugs to improve their efficacy and decrease the likelihood of side effects. We hope that research on the carbohydrate composition of the ocular surface will not only provide new information on ocular surface biology and disease, but will also help to develop new approaches to prevent and cure ocular surface disorders.
N-Glycosylation and Ocular Surface Homeostasis
Disruption of barrier function at the ocular surface epithelia is associated with a wide range of disorders that include dry eye—an age-related disease affecting millions of people worldwide and whose pharmacological treatment remains unresolved. Terminally differentiated stratified epithelial cells in cornea and conjunctiva maintain barrier function through a specialized protective structure composed of transmembrane mucins, a group of heavily glycosylated proteins characterized by extremely large extracellular domains. Galactosyl residues on mucin glycans are cross-linked on the apical glycocalyx by the multimeric protein galectin-3 to prevent cellular damage. Critical to preventing the decline in cellular function and homeostasis is the hexosamine pathway—a series of anabolic reactions that generate increased synthesis of N-glycan precursors. Activation of the hexosamine pathway leads to increased branching of N-glycans in the medial Golgi and the formation of cell-surface galectin-3 lattices that can modulate cell differentiation. Importantly, metabolic supplementation with hexosamine pathway metabolites is also known to enhance protein quality control mechanisms. Despite these critical roles, the relevance of N-glycosylation and the function of hesoxamine metabolites in ocular surface health and disease remains understudied.
We hypothesize that N- glycans play a dynamic role in ocular surface epithelial cells, changing in response to inflammation and driving mucin barrier and stress responses. The long-term objective of this proposal is to determine the contribution of the N-glycan branching in promoting ocular surface health, and whether activation of the hexosamine pathway can be used for therapeutic gain in the eye. The following specific aims will address this objective:
- Characterize mucin N-glycans in human corneal epithelial cells and their relationship to galectin-3 under normal and pro-inflammatory conditions
- Determine the regulatory role of N-glycans in promoting barrier function and reducing stress responses at the ocular surface
- Evaluate whether activation of the hexosamine pathway promotes ocular surface homeostasis.
This research will address the largely unstudied function of N-glycans in ocular surface barrier function and stress responses, and explore the potential of pharmacologically activating the hexosamine pathway for the treatment of ocular surface diseases.
CD147 and Corneal Wound Repair
The healing process after corneal injury is initiated through the release of a number of proteins that disassemble the epithelial junctions and contribute to the movement of the epithelial sheet to cover the wounded area. Matrix metalloproteinases (MMPs), a family of proteolytic enzymes that degrade components of the cell surface and extracellular matrix, are central to this process. Barely detected in the unwounded cornea, their induction is thought to play a key role during wound healing and in the establishment of chronic wounds. The production and activation of MMPs are tightly regulated by complex mechanisms that include homo-oligomerization of CD147, a heavily N-glycosylated transmembrane protein highly expressed in tumor cells.
We recently discovered that CD147 is a novel cell surface counter-receptor for galectin-3, a galactoside-binding lectin known to cluster cell surface receptors. More importantly, we found that clustering of CD147 by galectin-3 dramatically upregulates MMP9, the primary metalloproteinase synthesized and secreted by corneal epithelial cells migrating to resurface a wound.
The long-term objective of this proposal is to determine whether induction of CD147 clustering by galectin-3 is a powerful regulatory mechanism of the physiological and pathological remodeling processes associated with wound repair in the cornea. The following specific aims will address this objective:
- Investigate the role of CD147 clustering by galectin-3 as modulator of collective cell detachment and cell migration in corneal epithelial cells. We also aim to determine whether degradation of the galectin-3 by MMP9 inhibits CD147 clustering, thereby constituting a negative feedback mechanism to prevent sustained corneal remodeling
- Investigate the role of CD147 N-glycosylation in modulating galectin-3 binding affinity, CD147 clustering, and MMP9 induction
- Characterize the biological role of the CD147/galectin-3 complex in mouse models of wound healing and recurrent erosion, and determine whether inhibiting galectin-3 receptor clustering and CD147 function have a therapeutic potential during recurrent epithelial wound healing.
This research will explore, for the first time, the molecular mechanism linking glycan dynamics to the biological process by which wounded tissue initiates epithelial cell detachment and migration, and will provide better insight into the pathogenesis of chronic wounds.
Current Research Funding
NIH/NEI R01 EY024031: PI
CD147 and corneal wound repair
The long-term objective of this study is to determine whether induction of CD147 clustering on the cell surface glycocalyx is a regulatory mechanism of the physiological and pathological remodeling processes associated with wound repair in the cornea.
||NIH/NEI R01 EY026147: PI
N-glycosylation and ocular surface homeostasis
The long-term objective of this study is to explore the contribution of N-glycosylation to promoting barrier function and reducing stress responses in stratified ocular surface epithelia in vitro and in vivo, and to determine the potential of pharmacologically activating the N-glycosylation pathway at the ocular surface for therapeutic gain.
||NIH/NEI P30 EY003790: PI
Core grant for vision research
The goals of this grant are to support four research modules that facilitate and enhance interaction among the investigators in the various disciplines represented at the Schepens Eye Research Institute. The modules extend endeavors of individual research programs by providing opportunities for projects in which investigators do not have expertise, funding, or technical capabilities. The modules are: Morphology, Animal Resource, Laboratory Computer Applications and Flow Cytometry.