Macroevolutionary history of glycosylation and biostatistical analysis of environmental effects on N-glycosylation of immunoglobulin G

Glikozilacija je prisutna u svim živućim organizmima – od bakterija i arheja pa sve do čovjeka. Struktura glikana nije izravno zapisana u genomu nego je rezultat precizno kontrolirane aktivnosti proteina zaduženih za biosintezu glikana. Strukturne razlike glikana između vrsta su odgovor na selektivni pritisak, a svaka promjena koja je postala konzervirana u evoluciji nosi važnu ulogu. S druge strane, uočena je varijabilnost glikana unutar organizama jedne vrste što je dijelom rezultat okolišnih čimbenika i stanja pojedine jedinke. Cilj ovog rada je odrediti makroevolucijske trendove glikozilacije i analizirati utjecaj okolišnih čimbenika na N-glikom imunoglobulina G (IgG). Genomskom je filostratigrafijom određena starost gena koji kodiraju za glikoproteine i gena koji kodiraju za proteine koji sudjeluju u glikozilaciji. Dobiveni rezultati su pokazali da proteini koji sudjeluju u glikozilaciji vuku korijene još iz zajedničkog pretka svih staničnih organizama, uz pojedine inovacije u zajedničkom pretku svih eukariota, te manje u zajedničkom pretku pravih životinja. Unatoč starosti, glikozilacija u svoje zlatno doba ulazi razvojem višestaničnih životinja s ciljem razvoja međustanične komunikacije i interakcije stanica s okruženjem kada u većoj mjeri nastaju novi geni koji kodiraju za polipeptidne lance glikoproteina. S ciljem procjene utjecaja raznih čimbenika i stanja analizirana je povezanost podataka dostupnih u biobazi „10001 Dalmatinac“ s različitim deriviranim svojstvima Nglikoma IgG-a kao najproučavanijeg glikoproteina. Rezultati dobiveni analizom preko 3500 ljudi su pokazali da postoji utjecaj prehrane (učestalost konzumacije voćnih derivata i slatke hrane), hipertenzije, artritisa, regularnosti menstrualnog ciklusa, debljine, krvnog tlaka, koncentracije gliciranog hemoglobina, fibrinogena i inzulina na sintezu agalaktoziliranih glikana IgG-a. Zatim, digalaktozilacija IgG-a je povezana s hipertenzijom, artritisom, redovitošću menstrualnog ciklusa, debljinom, krvnim tlakom, mineralnom gustoćom kostiju, prehranom (voćni derivati, slatka hrana), koncentracijama urata, triglicerida, fibrinogena, inzulina, kolesterola i HDL kolesterola. Sijalinizacija IgG-a je povezana s regularnošću menstrualnog ciklusa, debljinom, mineralnom gustoćom kostiju, krvnim tlakom, koncentracijama triglicerida i inzulina. Udio struktura s račvajućim N-acetilglukozamin u N-glikomu IgG-a ovisi o mineralnoj gustoći kostiju, redovitošću menstrualnog ciklusa, pušenju, te koncentracijama triglicerida i kolesterola.Glycosylation is present in all living organisms - from bacteria and archaea to humans. The structure of glycans is not directly written in the genome but is the result of the precisely controlled activity of proteins responsible for glycan biosynthesis. The structural differences of glycans between species are a response to selective pressure, and any change that has become conserved in evolution plays an important role. On the other hand, variability of glycans within the organism of one species was observed, which is partly the result of environmental factors and the state of individual individuals. This thesis aims to determine the macroevolutionary trends of glycosylation and to analyse the influence of environmental factors on the N-glycome of immunoglobulin G. Genomic phylostratigraphy determined the evolutionary age of genes encoding glycoproteins and genes encoding proteins involved in glycosylation eukaryotes. Obtained results pointed out that the genes involved in glycosylation which we find today in humans, were present in all cellular organisms, with some innovations in the last common ancestor of all eukaryotes and less in the common ancestor of eumetazoans. Despite its ancient evolutionary age, glycosylation in its golden era enters with the development of multicellular animals when new genes encode polypeptide glycoprotein chains are increasingly emerging, probably intending to develop tools for cell-cell and cell-environment interaction. To assess the influence of various factors and conditions, the correlation of data available in the 10001 Dalmatian database with different derived properties of N-glycome immunoglobulin G (IgG), as the most studied glycoprotein, was analysed. The results obtained from the analysis of over 3500 people showed that there is an impact of diet (frequency of consumption of fruit derivatives and sugary foods), hypertension, arthritis, menstrual regularity, obesity, blood pressure and glycated haemoglobin, fibrinogen, and insulin concentration on IgG agalactosylation. Then, IgG digalactosylation is associated with hypertension, arthritis, menstrual regularity, obesity, blood pressure, bone mineral density, diet (fruit derivatives, sugary foods), urate, triglyceride, fibrinogen, insulin, cholesterol, and HDL cholesterol levels. Sialylation of IgG is associated with menstrual cycle regularity, obesity, bone mineral density, blood pressure, triglyceride, and insulin concentrations. The abundance of structures with branching N-acetylglucosamine in N-glycome IgG depends on bone mineral density, regularity of the menstrual cycle, smoking, and the concentration of triglycerides and cholesterol