GlycoLab- Functional Glycobiology
Our main research interests are focused on understanding glycan-protein interactions in the context of natural glycans present in an organism.
We approach this using the power of the high-throughput glycan microarray technology to identify functional glycan epitopes for proteins at a glycomics scale, and apply an integrative approach that combines glycan microarrays with structural biology to understand the molecular determinants of glycan recognition. We use this information to set-up functional studies aiming at characterising novel glycan-recognition systems.
Glycans play diverse roles in biology, mediating cell-cell, host-nutrient and host-pathogen interactions; and alterations in the glycosylation of proteins and lipids are associated with several diseases, including cancer. These biological functions of glycans occur through their specific recognition by glycan-binding proteins. Hence, the study of these interactions is crucial for discovering novel disease biomarkers and developing glycan-based diagnostics/therapies.
Glycan-mediated host-microbiome interactions
The human microbiome has adapted to the intestinal ecological niche by targeting different glycans (carbohydrates) as nutrients. The structures of glycans are complex and diverse and originate from the diet (dietary glycans) and from the mucosal mucin glycoprotein layer that protects the intestinal epithelium (host glycans). Diet changes to the glycan influx into the gut can restructure the composition of commensal or pathogenic bacteria that have adapted to use host glycans. Alterations of the mucosal glycan barrier, associated with an imbalance in the microbiome (dysbiosis), are attributed to the onset of several diseases, including inflammatory bowel disease, pathogen infection and cancer.
In this context, in the project GLYCOINTERACT (PTDC/BIA-MIB/31730/2017) we are characterising surface glycan-recognition systems of two representative strains of gut microbiota, Bacteroides thetaiotaomicron and B. ovatus, which have adapted to mammalian- or dietary-derived glycans, respectively. In collaboration with Ten Feizi’s group from Imperial College London, we are developing glycome-based microarrays (MOLECULAR & CELLULAR PROTEOMICS 2015; 14, 988) of dietary- or mammalian-type glycan structures potentially targeted by these bacteria. We integrate the information derived from high-throughput glycan microarray analysis of the bacterial proteins, with structural biology to understand the molecular determinants of glycan recognition (THE FEBS JOURNAL 2020; 287, 2723). This is an approach implemented in collaboration with the X-ray Crystallography Lab at UCIBIO (Ana Luisa Carvalho and Maria João Romão). The project also involves the (Bio)Molecular Structure and Interactions by NMR Lab at UCIBIO (Filipa Marcelo, Eurico Cabrita) and external collaborations with the University of Aveiro (Manuel Coimbra) and NZYTech genes and enzymes company (Carlos Fontes).
Integrative approach to study human microbiome glycan recognition systems at a structural and functional level
Glycan ligand discovery and specificity assignment for immune-lectins and anti-cancer antibodies
The recognition of glycans by effector proteins of the immune system is key to mediate signalling events in disease, including in tumour immune-invasion and progression. We are applying recently developed microarrays of structurally-defined glycans found in normal and tumour cells to identify the glycan ligands and assign specificity of immune-lectins and therapeutic antibodies. The engagement of macrophage-expressed human Siglec-15 with tumour cells expressing the sialyl Tn glycan triggers tumour growth. However, we showed that Siglec-15 binds with higher avidity to sialylated glycans other than sialyl-Tn and that these could be functional ligands, as Siglec-15 recognition of sialylated glycans on tumour cells is independent of sialyl-Tn antigen expression (GLYCOBIOLOGY, 2020). Due to the resulting immune-suppressive phenotype of the interactions of immune-lectins with tumour-associated glycan antigens, promising and attractive immunotherapies are being designed that exploit monoclonal antibodies specifically targeting these antigens. In collaboration with the GlycoImmunology Lab at UCIBIO (Paula Videira), we have assigned the unique glycan-binding specificity for a monoclonal antibody (mAbL2A5) targeting sialyl-Tn antigen (SCIENTIFIC REPORTS 2018; 8,12196), and that is now being developed for anti-cancer therapy. Following these studies and the implementation of the glycan microarrays, we have a programme for the pre-clinical characterisation of antibodies for the development of effective anti-cancer strategies, also in collaboration with biopharmaceutical companies.
“GLYCOINTERACT: Glycan-human microbiome interaction: glycan diversity and recognition in the human gut with impact on health and nutrition”, FCT-MCTES, Total funding: €234,280, Unit funding: € 176,405 + € 15,625 (NZYTech), Angelina Sá Palma (PI).
“GLYCANTIGENS: Advances in MUC1 Glycan Cancer Antigens: From structure to function in the fight against cancer”, FCT-MCTES, Total funding: €238,195, Unit funding: € 176,266, Angelina Sá Palma (Co-PI).
“INNOGLY, Innovation with Glycans: new frontiers from synthesis to new biological targets”, COST Action CA18103, Angelina Sá Palma (Management Committee member).
“Targeting glycan specificity of tumour-specific antibodies for development of effective anti-cancer strategies”, CRA Siamab Therapeutics, Total Funding: €10,000, Angelina Sá Palma (PI).
Murugesan G; Correia VG; Palma AS; Chai W; Li C; Feizi T; Martin E; Laux B; Franz A; Fuchs K; Weigle B; Crocker PR. 2020. Siglec-15 recognition of sialoglycans on tumor cell lines can occur independently of sialyl Tn antigen expression.. GLYCOBIOLOGY, DOI: 10.1093/glycob/cwaa048
Diana ORibeiro; Aldino Viegas; Virgínia MRPires; João Medeiros‐Silva; Pedro Bule; Wengang Chai; Filipa Marcelo; Carlos MGAFontes; Eurico JCabrita; Angelina SPalma; Ana Luísa Carvalho. 2019. Molecular basis for the preferential recognition of β1,3‐1,4‐glucans by the family 11 carbohydrate‐binding module from Clostridium thermocellum. The FEBS Journal, DOI: 10.1111/febs.15162
Gao, T; Yan, JY; Liu, CC; Palma, AS; Guo, ZM; Xiao, M; Chen, X; Liang, XM; Chai, WG; Cao, HZ. 2019. Chemoenzymatic Synthesis of O-Mannose Glycans Containing Sulfated or Nonsulfated HNK-1 Epitope. JOURNAL OF THE AMERICAN CHEMICAL SOCIETY, 141, DOI: 10.1021/jacs.9b08964
Loureiro LR; Sousa DP; Ferreira D; Chai W; Lima L; Pereira C; Lopes CB; Correia VG; Silva LM; Li C; Santos LL; Ferreira JA; Barbas A; Palma AS; Novo C; Videira PA. 2018. Novel monoclonal antibody L2A5 specifically targeting sialyl-Tn and short glycans terminated by alpha-2-6 sialic acids.. Scientific Reports, DOI: 10.1038/s41598-018-30421-w
Palma, AS; Liu, Y; Zhang, HT; Zhang, YB; McCleary, BV; Yu, GL; Huang, QL; Guidolin, LS; Ciocchini, AE; Torosantucci, A; Wang, DN; Carvalho, AL; Fontes, CMGA; Mulloy, B; Childs, RA; Feizi, T; Chai, WG. 2015. Unravelling Glucan Recognition Systems by Glycome Microarrays Using the Designer Approach and Mass Spectrometry. MOLECULAR & CELLULAR PROTEOMICS, 14, DOI: 10.1074/mcp.M115.048272