Day 13 :
- Glycobiology
Session Introduction
Yolanda Mthembu
Dept. of Clinical Chemistry and Blood Transfusion, Gothenburg University, Sweden
Title: Binding of the gastric pathogen Helicobacter pylori to recombinant mucin fusion proteins carrying Leb, SLex, LacdiNAc and GlcNAcα1,4Gal determinants on O-glycan cores
Biography:
Yolanda Mthembu is currently a PhD student at the Department of Laboratory Medicine, University of Gothenburg, Sweden. She was formally accepted in January 2014 and works in a PhD project within the 7th framework program-sponsored Initial Training Network entitled “Systems Glycobiology of Gastric Cancer” (Acronym: GastricGlycoExplorer). Further, she has during her whole PhD program been involved in teaching in the department corresponding to 20% of full time. Her project is progressing according to plan and she is expected to defend her PhD thesis in September 2019.
Abstract:
Helicobacter pylori attach to mucin-glycans with two major attachment prtoteins; the blood group antigen-binding adhesin, BabA, which binds to ABO and Lewis b (Leb) (Fucα1, 2Galβ1,3[Fucα1,4]GlcNAc1-R) and, H type-1 (Fucα1,2Galβ1,3GlcNAc1-R) histo-blood group antigens and, in addition with the sialic acid-binding adhesin, SabA, which binds to sialylated atigens including, sialyl-Lewisx (SLex)(NeuAcα2,3Galβ1,4[Fucα1,3]GlcNAc1-R).
The CHO-K1 cells were genetically engineered to express a mucin-type fusion protein (PSGL-1/mIgG2b) tghat carry Leb and SLex determinants on core 2, core 3 and extended core 1 O-glycans. PSGL-1/mIgG2b that carry LacdiNAc on core 2 and the GlcNAcα1,4Gal1 determinant on core 1 were also expressed by CHO-K1. Immunoblots by lectins and mAbs combend with LC-MS of released glycans were used to identify the O-glycomes of the PSGL-1/mIgG2b proteins. Further, the inhibition of binding of the H. pylori 17875/Leb that express BabA and, the almsot isogenic H. pylori DM that instead express SabA, by the seriues of glyco-engineered PSGL-1/mIgG2b proteins was assessed.
The presence of the Leb, SLex, LacdiNAc and GlcNAcα1,4Gal determinants on PSGL-1/mIgG2b was first confirmed. The H. pylori experiments demonstrated that only PSGL-1/mIgG2b proteins with Leb on core 3 inhibited BabA-mediated binding. On the other hand, the seris of sialylated PSGL-1/mIgG2b proteins all demonstaretd various degrees of inhibition of SabA-mediated binding, suggesting that SabA accepts various substitutyion of sLex for binding, simiar to babA that accets a serios of derivatis of the ABO series (albeit restricted tyo the acto series type 1 core chains).
Abdul Rouf Mir
Department of Biochemistry, Jawaharlal Nehru Medical College, Faculty of Medicine, AMU, Aligarh, Uttar Pradesh, India
Title: Glycoxidation mediated amorphous aggregation of linker histone H1 generates specific auto-antibodies in patients with cancer of lungs and prostate.
Biography:
Dr. Abdul Rouf Mir is working as a Senior Resident in the Department of Biochemistry,
Faculty of Medicine, Aligarh Muslim University, Aligarh, India. He has completed PhD in
2014, and has published 20 research papers/reviews in peer reviewed international journals.
He has worked on the role of carbohydrate derived dicarbonyls in the chemical modifications
of nuclear proteins and studied the generation of neo-epitopes upon them and worked out
their role in the immunopathology of cancer, pleading the possibility of glycoxidatively
modified histones as bioprobes for the early detection of cancer. He has expertise in protein
biochemistry, biophysics, immunology of cancer & diabetes and clinical studies.
Abstract:
Aberrant non enzymatic protein modifications under glycoxidation and AGE-RAGE axis
have emerged as a promising research in the field of cancer. Glycoxdiation makes proteins
immunogenic and stimulates specific humoral immune responses. We studied methylglyoxal
induced H1 histone modifications and their role in immunopathology of cancer. We observed
lysine side chain modifications, blocking of free amino groups and the formation of
condensed cross structures in histone H1. It generated N
É›
-(carboxyethyl) lysine (CEL) as
observed in MALDI-MS, HPLC and LCMS. MG-H1 appeared as an amorphous aggregate
under electron microscopy and gave altered binding with DNA in CD studies. The modified
histone elicited high titre immunogen specific antibodies in rabbits when compared to the
native, thus pointing towards the generation of neo-epitopes in MG-H1. The auto-antibodies
derived from cancer patients exhibited enhanced binding with MG-H1 as compared to the
native histone in ELISA, gel retardation assay and Western blot analysis. MG-1 may be
considered as potential antigenic candidate for autoimmune response in cancer with potential
role as a biomarker for early detection of cancers.