title: Calmodulin-binding proteins in human Y-79 retinoblastoma and HTB-14 glioma cell lines.
abstract: The Y-79 human retinoblastoma cell line has been used as a model system for studying differentiation of primitive neuroectodermal cells into either glial-like (glial fibrillary acidic protein positive) or neuron-like (neuron-specific enolase-positive) cells. To determine whether Y-79 retinoblastoma cells express neuronotypic calmodulin-binding proteins, Y-79 cells were either treated with butyrate or dibutyryl cyclic AMP (dbcAMP) in serum-containing medium or were maintained in serum-free media. Using a biotinylated calmodulin blot overlay technique, we found that Y-79 cells treated with dbcAMP or butyrate expressed low levels of membrane-bound calmodulin-binding proteins of 150, 147, 127, and 126 kilodaltons (kDa); butyrate-treated cells also expressed a calmodulin-binding peptide of 135 kDa. Since butyrate treatment of Y-79 cells induces the expression and the secretion of interphotoreceptor retinoid-binding protein (IRBP, 140 kDa), we tested the hypothesis that the calmodulin-binding protein of 135 kDa induced by butyrate treatment was IRBP. Purified bovine IRBP did not bind calmodulin; further, the 135-kDa calmodulin binding protein was not immunoreactive with antisera directed against IRBP. Since dbcAMP and butyrate induce some glial-like characteristics in Y-79 cells, we compared the calmodulin-binding protein pattern in these cells with that seen in human HTB-14 glioma cells. The HTB-14 line did not express calmodulin-binding proteins, even after treatments with agents that induce morphologic change in these cells. Thus, we conclude that Y-79 cells express membrane-bound calmodulin-binding proteins, but in a pattern different from that seen with adult, differentiated neurons or from human HTB-14 glioma cells.
authors.affiliation: Department of Pharmacology, Milton S. Hershey Medical Center, Pennsylvania State University, Hershey 17033.
authors.forename: K R
authors.initials: KR
authors.lastname: Pennypacker
authors.forename: A
authors.initials: A
authors.lastname: Kyritsis
authors.forename: G J
authors.initials: GJ
authors.lastname: Chader
authors.forename: M L
authors.initials: ML
authors.lastname: Billingsley
mesh_terms: D001710:Biotin; D003994:Bucladesine / Q000494:pharmacology; D002087:Butyrates / Q000494:pharmacology; D020148:Butyric Acid; D002148:Calmodulin-Binding Proteins / Q000378:metabolism*; D002454:Cell Differentiation; D002462:Cell Membrane / Q000378:metabolism; D003600:Cytosol / Q000378:metabolism; D004591:Electrophoresis, Polyacrylamide Gel; D005136:Eye Proteins; D005910:Glioma / Q000378:metabolism*; D006801:Humans; D007118:Immunoassay; D012175:Retinoblastoma / Q000378:metabolism*; D012177:Retinol-Binding Proteins / Q000378:metabolism; D014407:Tumor Cells, Cultured; D000099214:Retinol-Binding Proteins, Interstitial
chemical_list: D001710:Biotin; D003994:Bucladesine; D002087:Butyrates; D020148:Butyric Acid; D002148:Calmodulin-Binding Proteins; D005136:Eye Proteins; D012177:Retinol-Binding Proteins; D000099214:Retinol-Binding Proteins, Interstitial