engleski

Glycosylation of Stress Glycoprotein GP62 in Cells Exposed to Heat-shock and Subculturing

GP62 is a member of the stress glycoprotein family that was proposed to have a chaperone-like function in the heat-shock response. Using lectin blotting we have analyzed glycosylation of GP62 in A1235 cells exposed to heat-shock (2 h at 42ºC), subculturing and UV-radiation. As expected, heat-shock resulted in the appearance of significant amounts of GP62, which was undetectable in the control cells. SNA, DSA and PHA-E lectins recognized GP62, while BSA I, Con A, RCA I, SJA, UEA-I, VVA and WGA did not. Based on this information, it is possible to identify some segments of carbohydrate structures attached to GP62. GP62 appears to contain a bianntenary complex-type oligosaccharide with at least one a(2,6)-linked sialic acid, N-acetyllactosamine and bissecting b(1,4)-linked N-acetylglucosamine. While performing these experiments we noticed that heat-shock is not necessary for the induction of GP62, and that even simple subculturing of cells was a sufficient stimulus. However, the dynamics of the induction was somewhat different. When GP62 was induced by a heat-shock, it appeared within 4 h after the end of heat treatment and remained on a relatively high level for at least next 24 h. After subculturing, GP62 appeared after only 2 h, stayed on a high level during the following 2 h, and virtually disappeared after 24 h. Interestingly, glycosylation of GP62 induced by subculturing was found to be different from glycosylation of GP62 induced by heat-shock. In addition to SNA, DSA and PHA-E lectins, which recognized GP62 induced by heat-shock, GP62 induced by subculturing was also recognized by RCA I and WGA lectins. Thus, in addition to carbohydrates present on GP62 induced by heat-shock, GP62 induced by subculturing contained terminal galactose and N-acetylglucosamine residues. Contrary to heat-shock and subculturing, when cells were exposed to UV-C radiation, GP62 did not appear, suggesting that it is associated with some, but not all, cellular stress-response pathway.

Glycobiology; Glycoproteins; Heat-shock; Stress

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