Sialic‐Acid Content of Low‐Density Lipoproteins Controls Their Binding and Uptake by Cultured Cells

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Abstract
The (high‐affinity receptor)‐mediated uptake of homologous low‐density (low‐ϱ) lipoproteins by cultured human arterial smooth muscle cells or human skin fibroblasts is controlled by the sialic acid content of low‐ϱ lipoprotein particles. This conclusion is derived from the following results.1. Gangliosides incubated with native low‐ϱ lipoproteins associate with low‐ϱ lipoprotein particles. Low‐ϱ lipoproteins modified by associated GLac1, GGtet1, and GGtet2b + GGtet3 gangliosides are internalized by arterial smooth muscle cells at a rate up to 80% lower than native low‐ϱ lipoproteins or those preincubated with desialized gangliosides.2. The inhibitory effect of gangliosides is specific for high affinity uptake and not detectable on skin fibroblasts deficient in low‐ϱ lipoprotein receptor.3. Desialyzed low‐ϱ lipoproteins are internalized by smooth muscle cells up to 100% faster than native low‐ϱ lipoproteins, the enhancement of uptake corresponding to the degree of desialization.