Processing of asparagine-linked oligosaccharides is an early biochemical marker of the enterocytic differentiation of HT-29 cells

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Abstract
The inability of HT‐29 cells to undergo an enterocytic differentiation when grown in a glucose‐containing (Glc+) medium has been recently correlated to an overall impairment of N‐glycan processing. These results were obtained using confluent HT‐29 cells in which the differentiation characteristics are fully expressed under differentiation permissive conditions (glucose‐deprived medium, Glc−). Whether these changes of N‐glycan processing appear progressively during the cell growth or are already present from the beginning of the culture was investigated in this work by comparing the actual status of N‐glycan processing in both exponentially growing Glc+ and Glc− HT‐29 cells. Under these conditions, HT‐29 cells do not express any characteristics of enterocytic differentiation, even when grown in differentiation permissive conditions. We show here that the conversion of high‐mannose to complex glycoproteins is, however, severely reduced in HT‐29 cells grown studied. In contrast, HT‐29 cells grown in differentiation permissive conditions (HT‐29 Glc−) display a normal pattern of N‐glycan processing in both the exponential and the stationary phase of growth. We also show that both growing and confluent HT‐29 Glc+ cells accumulate Man9–8 GlcNAc2 species, thus suggesting that there is an important regulatory point at this level. We therefore conclude that the N‐glycan processing may be used as an early biochemical probe for the enterocytic differentiation of HT‐29 cells. Whether these early changes result from an early metabolic regulation or are the consequence of a genetic control remains to be studied.