HIGHLY SPECIFIC ANTIBODY TO ROUS-SARCOMA VIRUS SRC GENE-PRODUCT RECOGNIZES NUCLEAR AND NUCLEOLAR ANTIGENS IN HUMAN-CELLS

An antiserum to the Rous sarcoma virus-transforming protein pp60(v-src ), raised in rabbits immunized with the bacterially produced protein a lpha p60 serum (M. D. Resh and R L. Erikson, J. Cell Biol. 100:409-417 , 1985) previously reported to detect very specifically a novel popula tion of pp60(v-src) and pp6(c-src) molecules associated with juxtareti cular nuclear membranes in normal and Rous sarcoma virus-infected cell s of avian and mammalian origin, was used here to investigate by immun ofluorescence microscopy localization patterns of src molecules in hum an cell lines, either normal or derived from spontaneous tumors. We fo und that the alpha p60 serum reveals nuclear and nucleolar concentrati ons of antigens in all the human cell Lines tested and in two rat and mouse hepatoma cell lines derived from adult tumorous tissues but not in any established rat and mouse cell lines either untransformed or tr ansformed lay the spe and ras oncogenes, Both the nuclear and nucleola r stainings can be totally extinguished by preincubation of the serum with highly purified chicken c-Src; We show also that the partitioning of the alpha p60-reactive proteins among the whole nucleus and the nu cleolus depends mostly on two different parameters: the position in th e cell cycle and the degree of cell confluency. Our observations raise the attractive possibility that, in differentiated cells, pp60(c-src) and related proteins plight be involved not only in mediating the tra nsduction of mitogenic signals at the plasma membrane level but also i n controlling progression through the cell cycle and entry in mitosis by interacting with cell division cycle regulatory components at the n uclear level.