Inhibition of nucleolar protein nucleolin by electroporation with anti-nucleolin antibodies results in an increase of the nucleolar size.
Electroporation of exponentially growing human larynx epidermoid carcinoma cells (HEp-2) with a serum against nucleolin, one of the most abundant non-histone nuclear proteins, has shown, 24 h after electroporation, a significant increase in the size of the nucleolus of these cells compared with normal HEp-2 cells (non-electroporated) and electroporated HEp-2 cells in the absence of anti-nucleolin serum (P < 0.01). Image analysis evaluation of the different nucleolar components proved a major contribution of the dense fibrillar component to the total nucleolar size in cells electroporated with anti-nucleolin antibodies, more than that corresponding to the dense fibrillar component in cells from any of the control groups (P < 0.01), indicating that the reported increase in nucleolar size was due to a marked enlargement of the dense fibrillar regions. These results, in agreement with previous biochemical and molecular biology studies, suggest a pivotal role for nucleolin in pre-rRNA processing and constitute morphological evidence supporting this role. Following nucleolin inhibition, impaired pre-rRNA processing might result in an accumulation of this molecular species in the dense fibrillar component of the nucleolus, where pre-rRNA is first present.
Abadía-Molina
F
F
Department of Cell Biology, Faculty of Science, University of Granada, Spain.
Torreblanca
J
J
García-Herdugo
G
G
Moreno
F J
FJ
D000906:Antibodies / Q000008:administration & dosage; D002460:Cell Line; D002466:Cell Nucleolus / Q000378:metabolism* / Q000648:ultrastructure*; D018274:Electroporation; D006801:Humans; D008854:Microscopy, Electron; D009687:Nuclear Proteins / Q000037:antagonists & inhibitors* / Q000276:immunology / Q000378:metabolism*; D010750:Phosphoproteins / Q000037:antagonists & inhibitors* / Q000276:immunology / Q000378:metabolism*; D012322:RNA Precursors / Q000378:metabolism; D012323:RNA Processing, Post-Transcriptional; D016601:RNA-Binding Proteins / Q000037:antagonists & inhibitors* / Q000276:immunology / Q000378:metabolism*; D000097796:Nucleolin
D000906:Antibodies; D009687:Nuclear Proteins; D010750:Phosphoproteins; D012322:RNA Precursors; D016601:RNA-Binding Proteins; D000097796:Nucleolin