EXPRESSION OF THE NEUROFIBROMATOSIS-I GENE-PRODUCT, NEUROFIBROMIN, IN BLOOD-VESSEL ENDOTHELIAL-CELLS AND SMOOTH-MUSCLE

Vascular pathology is an underestimated complication of neurofibromatosis 1 (NF1). Manifestations include renovascular stenosis with associated hypertension, cerebrovascular occlusion, visceral ischaemia and aneurysms of smaller arteries. This is illustrated by a woman recently evaluated in our Neurofibromatosis Program who had multiple cerebrovascular and renovascular abnormalities. To determine the contribution of NF1 expression to NF1 vasculopathy, the expression of the NF1 gene product, neurofibromin, was examined in blood vessels. Neurofibromin was detected in the endothelial cell layer of rat cerebral vessels, renal arteries, and aorta by immunohistochemistry. Cultured bovine cerebral endothelial cells were found to express NF1 mRNA by RT-PCR and neurofibromin by Western immunoblotting and immunocytochemistry. Neurofibromin expression was also detected in the smooth muscle layer of the aorta but not of cerebral or renal vessels. The vascular abnormalities of NF1 are reviewed and possible pathogenesis with respect to neurofibromin expression is discussed.