title: Expression of the TSC2 product tuberin and its target Rap1 in normal human tissues.
abstract: The tuberous sclerosis-2 (TSC2) gene is linked to tuberous sclerosis (TSC), a dominantly inherited genetic syndrome in which inactivation of the normal TSC2 allele is associated with the development of mostly benign tumors and focal dysplasias. TSC2 encodes the protein tuberin, which is a widely expressed 180-kd polypeptide that exhibits specific GTPase activating activity toward Rap1 in vitro and co-localizes with Rap1 in cultured cells. In this study, we have performed immunohistochemical analyses, using affinity-purified anti-tuberin antibodies, to study the distribution of tuberin in a panel of normal human organs that are commonly affected by TSC. Cryosections indicated that tuberin is widely expressed at low levels. More intense staining of tuberin, in the cryosections and in paraffin sections, was observed in the small blood vessels of many organs, including the kidney, skin, and adrenal gland. High levels of tuberin were also detected in cortical neurons and cerebellar Purkinje cells. These findings imply that loss-of-function mutations in TSC2 might lead to the development of highly vascularized tumors, subcortical tubers, and focal atrophy of the cerebellar cortex, which are features commonly associated with TSC. Moreover, Rap1 was also found to be highly expressed in many of the same cells that contained high levels of tuberin, suggesting a functional interaction between tuberin and Rap1 in these tissues.
authors.affiliation: Laboratory of Cellular Oncology, National Cancer Institute, Bethesda, Maryland 20892, USA.
authors.forename: R
authors.initials: R
authors.lastname: Wienecke
authors.forename: J C
authors.initials: JC
authors.lastname: Maize
authors.forename: J A
authors.initials: JA
authors.lastname: Reed
authors.forename: J
authors.initials: J
authors.lastname: de Gunzburg
authors.forename: R S
authors.initials: RS
authors.lastname: Yeung
authors.forename: J E
authors.initials: JE
authors.lastname: DeClue
mesh_terms: D002540:Cerebral Cortex / Q000737:chemistry; D019204:GTP-Binding Proteins / Q000096:biosynthesis* / Q000737:chemistry; D016147:Genes, Tumor Suppressor; D006801:Humans; D007150:Immunohistochemistry; D007668:Kidney / Q000737:chemistry; D009206:Myocardium / Q000737:chemistry; D012097:Repressor Proteins / Q000096:biosynthesis* / Q000737:chemistry / Q000235:genetics*; D012867:Skin / Q000737:chemistry; D014402:Tuberous Sclerosis / Q000235:genetics* / Q000473:pathology; D000077005:Tuberous Sclerosis Complex 2 Protein; D025521:Tumor Suppressor Proteins; D020668:rap GTP-Binding Proteins
chemical_list: D012097:Repressor Proteins; C000624653:TSC2 protein, human; D000077005:Tuberous Sclerosis Complex 2 Protein; D025521:Tumor Suppressor Proteins; D019204:GTP-Binding Proteins; D020668:rap GTP-Binding Proteins