title: Nucleolin protein interacts with microprocessor complex to affect biogenesis of microRNAs 15a and 16.
abstract: MicroRNAs (miRNA) are endogenous, short, non-coding RNA that undergo a multistep biogenesis before generating the functional, mature sequence. The core components of the microprocessor complex, consisting of Drosha and DGCR8, are both necessary and sufficient for this process, although accessory proteins have been found that modulate the biogenesis of a subset of miRNA. Curiously, many of the proteins involved in miRNA biogenesis are also needed for ribosomal RNA processing. Here we show that nucleolin, another protein critical for rRNA processing, is involved in the biogenesis of microRNA 15a/16 (miR-15a/16), specifically at the primary to precursor stage of processing. Through overexpression and knockdown studies, we show that miR-15a/16 levels are directly correlated to nucleolin expression. Furthermore, we found that cellular localization is critical for the proper functioning of nucleolin in this pathway and that nucleolin directly interacts with DGCR8 and Drosha in the nucleus. Nucleolin can bind to the primary miRNA both directly and specifically. Finally, we show that in the absence of nucleolin, cell extracts are unable to process miR-15a/16 in vitro and that this can be rescued by the addition of nucleolin. Our findings offer a new protein component in the microRNA biogenesis pathway and lend insight into miRNA dysregulation in certain cancers.
authors: Department of Molecular and Cellular Oncology, The University of Texas MD Anderson Cancer Center, Houston, Texas 77030; Cancer Biology Program, The University of Texas Graduate School of Biomedical Sciences, Houston, Texas 77030. Electronic address: bpickeri@mdanderson.org.
authors: Brian F
authors: BF
authors: Pickering
authors: Department of Molecular and Cellular Oncology, The University of Texas MD Anderson Cancer Center, Houston, Texas 77030; Cancer Biology Program, The University of Texas Graduate School of Biomedical Sciences, Houston, Texas 77030. Electronic address: dyu@mdanderson.org.
authors: Dihua
authors: D
authors: Yu
authors: Department of Chemistry and Physics, Western Carolina University, Cullowhee, North Carolina 28723.
authors: Michael W
authors: MW
authors: Van Dyke
mesh_terms: D045744:Cell Line, Tumor; D002466:Cell Nucleolus / Q000378:metabolism; D005786:Gene Expression Regulation; D057809:HEK293 Cells; D006801:Humans; D035683:MicroRNAs / Q000737:chemistry* / Q000378:metabolism; D010750:Phosphoproteins / Q000737:chemistry* / Q000378:metabolism; D011485:Protein Binding; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000378:metabolism; D012313:RNA / Q000378:metabolism; D012335:RNA, Ribosomal / Q000378:metabolism; D016601:RNA-Binding Proteins / Q000737:chemistry* / Q000378:metabolism; D015398:Signal Transduction; D013347:Subcellular Fractions / Q000378:metabolism; D000097796:Nucleolin
chemical_list: D035683:MicroRNAs; D010750:Phosphoproteins; D019253:Proto-Oncogene Proteins c-bcl-2; D012313:RNA; D012335:RNA, Ribosomal; D016601:RNA-Binding Proteins; D000097796:Nucleolin; C505361:MIRN15 microRNA, human; C505362:MIRN16 microRNA, human