Glycosylation of fibronectin and other proteins in tissues of patients with tuberous sclerosis

SDS-polyacrylamide gel electrophoresis and Western blotting has been used to study the proteins and glycoproteins of tumours and apparently unaffected tissue obtained by surgery or post mortem from brains of individuals with tuberous sclerosis. Staining for protein and for carbohydrate, with lectins, of tumour-derived samples gave patterns consistenly different from those derived from normal individuals. Corresponding patterns from unaffected tuberous sclerotic tissue were indistinguishble from the normal pattern. Total glycopeptides were obtained by Pronase digestion of extracts of tumours and brain tissue. After chromatographic fractionation on Con A-Sepharose, their carbohydrate composition was determined by gas liquid chromatography. No major differences were revealed. Fibroblasts grown from skin and skin lesions of tuberous sclerosis patients and from sex- and age-matched normal individuals have been metabolically labelled with radiolabelled amino acid or carbohydrate precursors. The synthesis and secretion of glycoproteins have been studied using SDS-PAGE of cell extract and/or spent medium followed by slicing of the gel and radioassay of gel slices, or fluorography of the dried gel. Cultures of fibroblasts from TS patients exhihit an increased glycosylation of proteins when compared with normal. The increased glycosylation is more prominent in the area of 54, 80, 90, 110-190 and 200-240 kDa. The 220 kDa glycoprotein has been identified immunochemically to be fibronectin. Its synthesis, secretion and glycosylation is increased in fibroblasts grown from skin lesions of TS patients compared to those from the unaffected skin of the same patients, which in turn is higher than normal skin.