Abstract
Type I spinal muscular atrophy (SMA) is an autosomal recessive disorder caused by loss or mutations of the survival motor neuron 1 (SMN1) gene. The reduction in SMN protein levels in SMA leads to degeneration and death of motor neurons. In this study, we have analyzed the nuclear reorganization of Cajal bodies, PML bodies and nucleoli in type I SMA motor neurons with homozygous deletion of exons 7 and 8 of the SMN1 gene. Western blot analysis revealed a marked reduction of SMN levels compared to the control sample. Using a neuronal dissociation procedure to perform a careful immunocytochemical and quantitative analysis of nuclear bodies, we demonstrated a severe decrease in the mean number of Cajal bodies per neuron and in the proportion of motor neurons containing these structures in type I SMA. Moreover, most Cajal bodies fail to recruit SMN and spliceosomal snRNPs, but contain the proteasome activator PA28γ, a molecular marker associated with the cellular stress response. Neuronal stress in SMA motor neurons also increases PML body number. The existence of chromatolysis and eccentric nuclei in SMA motor neurons correlates with Cajal body disruption and nucleolar relocalization of coilin, a Cajal body marker. Our results indicate that the Cajal body is a pathophysiological target in type I SMA motor neurons. They also suggest the Cajal body-dependent dysfunction of snRNP biogenesis and, therefore, pre-mRNA splicing in these neurons seems to be an essential component for SMA pathogenesis.
Similar content being viewed by others
References
Alías L, Bernal S, Fuentes-Prior P, Barceló MJ, Also E, Martínez-Hernández R, Rodríguez-Alvarez FJ, Martín Y, Aller E, Grau E, Peciña A, Antiñolo G, Galán E, Rosa AL, Fernández-Burriel M, Borrego S, Millán JM, Hernández-Chico C, Baiget M, Tizzano EF (2009) Mutation update of spinal muscular atrophy in Spain: molecular characterization of 745 unrelated patients and identification of four novel mutations in the SMN1 gene. Hum Genet 125:29–39
Alías L, Bernal S, Barceló MJ, Also-Rallo E, Martínez-Hernández R, Rodríguez-Alvarez FJ, Hernández-Chico C, Baiget M, Tizzano EF (2011) Accuracy of marker analysis, quantitative real-time polymerase chain reaction, and multiple ligation-dependent probe amplification to determine SMN2 copy number in patients with spinal muscular atrophy. Genet Test Mol Biomarkers 15:587–594
Baltanas F, Casafont I, Weruaga E, Alonso JR, Berciano MT, Lafarga M (2011) Nucleolar disruption and Cajal body disassembly are nuclear hallmarks of DNA damage-induced neurodegeneration in Purkinje cells. Brain Pathol 21:374–388
Berciano MT, Novell M, Villagra NT, Casafont I, Bengoechea R, Val-Bernal JF, Lafarga M (2007) Cajal body number and nucleolar size correlate with the cell body mass in human sensory ganglia neurons. J Struct Biol 158:410–420
Bernardi R, Pandolfi PP (2007) Structure, dynamics and functions of promyelocytic leukaemia nuclear bodies. Natl Rev Mol Cell Biol 8:1006–1016
Boulon S, Westman BJ, Hutten S, Boisvert FM, Lamond AI (2010) The nucleolus under stress. Mol Cell 40:216–227
Burghes AH, Beattie CE (2009) Spinal muscular atrophy: why do low levels of survival motor neuron protein make motor neurons sick? Nat Rev Neurosci 10:597–609
Carmo-Fonseca M (2002) New clues to the function of the Cajal body. EMBO Rep 3:726–727
Carvalho T, Almeida F, Calapez A, Lafarga M, Berciano MT, Carmo-Fonseca M (1999) The spinal muscular atrophy disease gene product, SMN: a link between snRNP biogenesis and the Cajal (coiled) body. J Cell Biol 147:715–728
Casafont I, Navascués J, Pena E, Lafarga M, Berciano MT (2006) Nuclear organization and dynamics of transcription sites in rat sensory ganglia neurons detected by incorporation of 5′-fluorouridine into nascent RNA. Neuroscience 140:453–462
Cauchi RJ (2010) SMN and Gemins: “we are family”…or are we? Bioessays 32:1077–1089
Cho S, Dreyfuss G (2010) A degron created by SMN2 exon 7 skipping is a principal contributor to spinal muscular atrophy severity. Genes Dev 24:438–442
Cioce M, Lamond AI (2005) Cajal bodies: a long history of discovery. Annu Rev Cell Dev Biol 21:105–131
Cioce M, Boulon S, Matera AG, Lamond AI (2006) UV-induced fragmentation of Cajal bodies. J Cell Biol 175:401–413
Coady TH, Lorson CL (2011) SMN in spinal muscular atrophy and snRNP biogenesis. Wiley Interdiscip Rev RNA 2:546–564
Coovert DD, Le TT, McAndrew PE, Strasswimmer J, Crawford TO, Mendell JR, Coulson SE, Androphy EJ, Prior TW, Burghes AH (1997) The survival motor neuron protein in spinal muscular atrophy. Hum Mol Genet 6:1205–1214
Crawford TO, Pardo CA (1996) The neurobiology of childhood spinal muscular atrophy. Neurobiol Dis 3:97–110
Cuscó I, Barceló MJ, Rojas-García R, Illa I, Gámez J, Cervera C, Pou A, Izquierdo G, Baiget M, Tizzano EF (2006) SMN2 copy number predicts acute or chronic spinal muscular atrophy but does not account for intrafamilial variability in siblings. J Neurol 253:21–25
Dellaire G, Bazett-Jones DP (2004) PML nuclear bodies: dynamic sensors of DNA damage and cellular stress. Bioessays 26:963–977
Dundr M, Hebert MD, Karpova TS, Stanek D, Xu H, Shpargel KB, Meier UT, Neugebauer KM, Matera AG, Misteli T (2004) In vivo kinetics of Cajal body components. J Cell Biol 164:831–842
Feldkötter M, Schwarzer V, Wirth R, Wienker TF, Wirth B (2002) Quantitative analyses of SMN1 and SMN2 based on real-time lightCycler PCR: fast and highly reliable carrier testing and prediction of severity of spinal muscular atrophy. Am J Hum Genet 70:358–368
Frugier T, Tiziano FD, Cifuentes-Diaz C, Miniou P, Roblot N, Dierich A, Le Meur M, Melki J (2000) Nuclear targeting defect of SMN lacking the C-terminus in a mouse model of spinal muscular atrophy. Hum Mol Genet 9:849–858
Frugier T, Nicole S, Cifuentes-Diaz C, Melki J (2002) The molecular bases of spinal muscular atrophy. Curr Opin Genet Dev 12:294–298
Gall JG (2000) Cajal bodies: the first 100 years. Annu Rev Cell Dev Biol 16:273–300
Gavrilov DK, Shi X, Das K, Gilliam TC, Wang CH (1998) Differential SMN2 expression associated with SMA severity. Nat Genet 20:230–231
Gilder AS, Hebert M (2011) Relationship of the Cajal body to the nucleolus. In: The nucleolus. Springer, Berlin, pp 361–380
Gilder AS, Do PM, Carrero ZI, Cosman AM, Broome HJ, Velma V, Martinez LA, Hebert MD (2011) Coilin participates in the suppression of RNA polymerase I in response to cisplatin-induced DNA damage. Mol Biol Cell 22:1070–1079
Hebert MD, Shpargel KB, Ospina JK, Tucker KE, Matera AG (2002) Coilin methylation regulates nuclear body formation. Dev Cell 3:329–337
Kolb SJ, Kissel JT (2011) Spinal muscular atrophy. Arch Neurol 68:979–984
Kwon DY, Motley WW, Fischbeck KH, Burnett BG (2011) Increasing expression and decreasing degradation of SMN ameliorate the spinal muscular atrophy phenotype in mice. Hum Mol Genet 20:3667–3677
Lafarga M, Berciano MT, Garcia-Segura LM, Andres MA, Carmo-Fonseca M (1998) Acute osmotic/stress stimuli induce a transient decrease of transcriptional activity in the neurosecretory neurons of supraoptic nuclei. J Neurocytol 27:205–217
Lafarga M, Berciano MT, Pena E, Mayo I, Castaño JG, Bohmann D, Rodrigues JP, Tavanez JP, Carmo-Fonseca M (2002) Clastosome: a subtype of nuclear body enriched in 19S and 20S proteasomes, ubiquitin, and protein substrates of proteasome. Mol Biol Cell 13:2771–2782
Lafarga M, Casafont I, Bengoechea R, Tapia O, Berciano MT (2009) Cajal’s contribution to the knowledge of the neuronal cell nucleus. Chromosoma 118:437–443
Lallemand-Breitenbach V, de Thé H (2010) PML nuclear bodies. Cold Spring Harb Perspect Biol 2:a000661
Lefebvre S, Bürglen L, Reboullet S, Clermont O, Burlet P, Viollet L, Benichou B, Cruaud C, Millasseau P, Zeviani M, le Paslier D, Frézal J, Cohen D, Weissenbach J, Munnich A, Melki J (1995) Identification and characterization of a spinal muscular atrophy-determining gene. Cell 80:155–165
Lefebvre S, Burlet P, Liu Q, Bertrandy S, Clermont O, Munnich A, Dreyfuss G, Melki J (1997) Correlation between severity and SMN protein level in spinal muscular atrophy. Nat Genet 16:265–269
Lemm I, Girard C, Kuhn AN, Watkins NJ, Schneider M, Bordonné R, Lührmann R (2006) Ongoing U snRNP biogenesis is required for integrity of Cajal bodies. Mol Biol Cell 17:3221–3231
Liu Q, Dreyfuss G (1996) A novel nuclear structure containing the survival of motor neurons protein. EMBO J 15:3555–3565
Lorson CL, Rindt H, Shababi M (2010) Spinal muscular atrophy. Mechanisms and therapeutic strategies. Hum Mol Genet 19:R111–R118
Matera AG, Shpargel KB (2006) Pumping RNA: nuclear bodybuilding along the RNP pipeline. Curr Opin Cell Biol 18:317–324
Matera AG, Terns RM, Terns MP (2007) Non-coding RNAs: lessons from the small nuclear and small nucleolar RNAs. Nat Rev Mol Cell Biol 8:209–220
Matera AG, Izaguire-Sierra M, Praveen K, Rajendra TK (2009) Nuclear bodies: random aggregates of sticky proteins or crucibles of macromolecular assembly? Dev Cell 17:639–647
Mentis GZ, Blivis D, Liuy W, Drobac E, Crowder ME, Kong L, Alvarez FJ, Sumner CJ, O’Donovan MJ (2011) Early functional impairment of sensory-motor connectivity in a mouse model of spinal muscular atrophy. Neuron 69:453–467
Misteli T (2008) Physiological importance of RNA and protein mobility in the cell nucleus. Histochem Cell Biol 129:5–11
Monani UR (2005) Spinal muscular atrophy: a deficiency in a ubiquitous protein; a motor neuron-specific disease. Neuron 48:885–896
Navascues J, Berciano MT, Tucker KE, Lafarga M, Matera AG (2004) Targeting SMN to Cajal bodies and nuclear gems during neuritogenesis. Chromosoma 112:398–409
Nizami Z, Deryusheva S, Gall JG (2010) The Cajal body and histone locus body. Cold Sring Harb Perspect Biol 2:a000653
Pena E, Berciano MT, Fernandez R, Ojeda JL, Lafarga M (2001) Neuronal body size correlates with the number of nucleoli and Cajal bodies, and with the organization of the splicing machinery in rat trigeminal ganglion neurons. J Comp Neurol 430:250–263
Platani M, Goldberg I, Swedlow JR, Lamond AI (2000) In vivo analysis of Cajal body movement, separation, and joining in live human cells. J Cell Biol 151:1561–1574
Rajendra TK, Gonsalvez GB, Walker MP, Shpargel KB, Salz HK, Matera AG (2007) A Drosophila melanogaster model of spinal muscular atrophy reveals a function for SMN in striated muscle. J Cell Biol 176:831–841
Renvoisé B, Khoobarry K, Gendron MC, Cibert C, Viollet L, Lefebvre S (2006) Distinct domains of the spinal muscular atrophy protein SMN are required for targeting to Cajal bodies in mammalian cells. J Cell Sci 119:680–692
Ruggiu M, McGovern VL, Lotti F, Saieva L, Li DK, Kariya S, Monani UR, Burgues AHM, Pellizzoni L (2012) A role for SMN exon 7 splicing in the selective vulnerability of motor neurons in spinal muscular atrophy. Mol Cell Biol 32:126–138
Salomoni P, Betts-Henderson J (2011) The role of PML in the nervous system. Mol Neurobiol 43:114–123
Shpargel KB, Matera AG (2005) Gemin proteins are required for efficient assembly of Sm-class ribonucleoproteins. Proc Natl Acad Sci USA 102:17372–17377
Smolinski DJ, Wróbel B, Noble A, Zienkiewicz A, Górska-Brylass A (2011) Periodic expression of Sm protein parallels formation of nuclear Cajal bodies and cytoplasmic snRNP-rich bodies. Histochem Cell Biol 136:527–541
Soler-Botija C, Ferrer I, Gich I, Baiget M, Tizzano EF (2002) Neuronal death is enhanced and begins during foetal development in type I spinal muscular atrophy spinal cord. Brain 125:1624–1634
Soler-Botija C, Cuscó I, Caselles L, López E, Baiget M, Tizzano EF (2005) Implication of fetal SMN2 expression in type I SMA pathogenesis: protection or pathological gain of function? J Neuropathol Exp Neurol 64:215–223
Stanek D, Neugebauer KM (2006) The Cajal body: a meeting place for spliceosomal snRNPs in the nuclear maze. Chromosoma 115:343–354
Tapia O, Bengoechea R, Berciano MT, Lafarga M (2010) Nuclear targeting of coilin is regulated by its hypomethylation state. Chromosoma 119:527–540
Tucker KE, Berciano MT, Jacobs EY, LePage DF, Shpargel KB, Rossire JJ, Chan EK, Lafarga M, Conlon RA, Matera AG (2001) Residual Cajal bodies in coilin knockout mice fail to recruit Sm snRNPs and SMN, the spinal muscular atrophy gene product. J Cell Biol 154:293–307
Villagrá NT, Berciano J, Altable M, Navascués J, Casafont I, Lafarga M, Berciano MT (2004) PML bodies in reactive sensory ganglion neurons of the Guillain-Barré syndrome. Neurobiol Dis 16:158–168
Young PJ, Le TT, Man NT, Burghes AH, Morris GE (2000) The relationship between SMN, the spinal muscular atrophy protein, and nuclear bodies in differentiated tissues and cultured cells. Exp Cell Res 256:365–374
Young PJ, Le TT, Dunckley M, Nguyen TM, Burghes AH, Morris GE (2001) Nuclear gems and Cajal (coiled) bodies in fetal tissues: nucleolar distribution of the spinal muscular atrophy protein, SMN. Exp Cell Res 265:252–261
Zhang R, So BR, Li P, Yong J, Glisovic T, Wan L, Dreyfuss G (2011) Structure of a key intermediate of the SMN complex reveals Gemin2′s crucial function in snRNP assembly. Cell 146:384–395
Acknowledgments
The authors wish to thank Saray Pereda and Raquel García-Ceballos for technical assistance. We would also like to thank Greg Matera for critical reading of this manuscript. This work was supported by the following grants: “Dirección General de Investigación” (BFU2008-00175 and BFU2011-23983), “Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas” (CIBERNED; CB06/05/0037) Spain, and Instituto de Salud Carlos III, Fondo de Investigación Sanitaria (08-0729) to EFT.
Author information
Authors and Affiliations
Corresponding author
Rights and permissions
About this article
Cite this article
Tapia, O., Bengoechea, R., Palanca, A. et al. Reorganization of Cajal bodies and nucleolar targeting of coilin in motor neurons of type I spinal muscular atrophy. Histochem Cell Biol 137, 657–667 (2012). https://doi.org/10.1007/s00418-012-0921-8
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1007/s00418-012-0921-8