Glycosaminoglycans of proliferating and non-proliferating cells
Glycosaminoglycans associated with 3 independent cell systems - the regenerating rat liver, human lymphocytes in culture, baby hamster kidney (BHK) cells in culture - were examined under different conditions of cell growth. In all 3 systems studied CSA and CSC were associated with growing cells while DS and HS were the major GAGS present in stationary cell populations. Elevated levels of HA were also associated with the regenerating rat liver and proliferating BHK cells. The effect of viral transformation on the nature of the GAG complement expressed by BHK cells was also assessed. There were indications that one of the changes occurring as a result of transformation might involve some alteration, in the metabolism of DS, a component, the relative amount of which, is frequently observed to be reduced in transformed cells. The effect of transformation on the degree of sulphation of HS was also investigated. Preliminary results seemed to indicate that the species associated with the transformed cell was less sulphated than the species isolated from the normal cell. However, further investigations showed no apparent difference between the two HS components. The production of a plasminogen activator by BHK and PyY-BHK cells was evaluated in growing and stationary cultures. Both cell lines produced an activator, which appeared to be urokinase-like, under both conditions of cell growth. The production of the activator was elevated in the transformed cell. The effects of standard GAGS on the AT-III mediated inhibition of plasmin and urokinase were studied and both Hep and HS potentiated the inhibition of these enzymes by the anti-proteinase. Following the observations described in 2, k and 5 a model, was proposed which attempted to link the expression of cell-surface associated GAGS with extracellular proteolytic events under different conditions of cell growth. This model, together with others, was discussed in an attempt to describe the possible roles of GAGS in the control of cellular proliferative activity and the mediation of cell contacts.