Residual Cajal Bodies in Coilin Knockout Mice Fail to Recruit Sm snRNPs and SMN, the Spinal Muscular Atrophy Gene Product

• Published in: The Journal of cell biology Vol. 154; no. 2; pp. 293 - 307
• Main Authors: Tucker, Karen E., Berciano, Maria Teresa, Jacobs, Erica Y., LePage, David F., Shpargel, Karl B., Rossire, Jennifer J., Edward K. L. Chan, Lafarga, Miguel, Conlon, Ronald A., Matera, A. Gregory
• Format: Journal Article
• Language: English
• Published: United States Rockefeller University Press 23.07.2001; The Rockefeller University Press
• Subjects: Animals; Antibodies; Autoantigens - metabolism; Blotting, Northern; Cell Line; Cell lines; Cell nucleolus; Cell Nucleolus - metabolism; Cell Nucleolus - ultrastructure; Cells; Cellular biology; Chromosomal Proteins, Non-Histone - metabolism; Coiled bodies; Coiled Bodies - genetics; Coiled Bodies - metabolism; Coiled Bodies - ultrastructure; Cyclic AMP Response Element-Binding Protein; Exons; Fetal Viability - genetics; Gene Expression - drug effects; Gene Targeting; Green Fluorescent Proteins; HeLa cells; Homozygote; Luminescent Proteins - genetics; Mice; Mice, Knockout - genetics; Nerve Tissue Proteins - metabolism; Nuclear Proteins - biosynthesis; Nuclear Proteins - deficiency; Nuclear Proteins - genetics; Nuclear Proteins - metabolism; Organ Specificity; Phosphoproteins - metabolism; Proteins; Recombinant Fusion Proteins - biosynthesis; Recombinant Fusion Proteins - genetics; Recombinant Fusion Proteins - pharmacology; Ribonucleoproteins, Small Nuclear - metabolism; RNA Splicing; RNA, Messenger; RNA-Binding Proteins; Rodents; Small nuclear ribonucleoproteins; SMN Complex Proteins; snRNP Core Proteins; Spine; Splicing; Survival Rate
• ISSN: 0021-9525; 1540-8140
• DOI: 10.1083/jcb.200104083

Cajal bodies (CBs) are nuclear suborganelles involved in the biogenesis of small nuclear ribonucleoproteins (snRNPs). In addition to snRNPs, they are highly enriched in basal transcription and cell cycle factors, the nucleolar proteins fibrillarin (Fb) and Nopp140 (Nopp), the survival motor neuron (SMN) protein complex, and the CB marker protein, p80 coilin. We report the generation of knockout mice lacking the COOH-terminal 487 amino acids of coilin. Northern and Western blot analyses demonstrate that we have successfully removed the fulllength coilin protein from the knockout animals. Some homozygous mutant animals are viable, but their numbers are reduced significantly when crossed to inbred backgrounds. Analysis of tissues and cell lines from mutant animals reveals the presence of extranucleolar foci that contain Fb and Nopp but not other typical nucleolar markers. These so-called "residual" CBs neither condense Sm proteins nor recruit members of the SMN protein complex. Transient expression of wild-type mouse coilin in knockout cells results in formation of CBs and restores these missing epitopes. Our data demonstrate that full-length coilin is essential for proper formation and/or maintenance of CBs and that recruitment of snRNP and SMN complex proteins to these nuclear subdomains requires sequences within the coilin COOH terminus.