The Musashi Family of RNA Binding Proteins: Master Regulators of Multiple Stem Cell Populations

  • Jessie M. Sutherland
  • Eileen A. McLaughlinEmail author
  • Gary R. Hime
  • Nicole A. Siddall
Part of the Advances in Experimental Medicine and Biology book series (AEMB, volume 786)


In order to maintain their unlimited capacity to divide, stem cells require controlled temporal and spatial protein expression. The Musashi family of RNA-binding proteins have been shown to exhibit this necessary translational control through both repression and activation in order to regulate multiple stem cell populations. This chapter looks in depth at the initial discovery and characterisation of Musashi in the model organism Drosophila, and its subsequent emergence as a master regulator in a number of stem cell populations. Furthermore the unique roles for mammalian Musashi-1 and Musashi-2 in different stem cell types are correlated with the perceived diagnostic power of Musashi expression in specific stem cell derived oncologies. In particular the potential role for Musashi in the identification and treatment of human cancer is considered, with a focus on the role of Musashi-2 in leukaemia. Finally, the manipulation of Musashi expression is proposed as a potential avenue towards the targeted treatment of specific aggressive stem cell cancers.


RNA binding proteins Stem cell niche Cancer stem cells 


  1. 1.
    Becker AJ, Mc CE, Till JE (1963) Cytological demonstration of the clonal nature of spleen colonies derived from transplanted mouse marrow cells. Nature 197:452–4PubMedCrossRefGoogle Scholar
  2. 2.
    Siminovitch L, McCulloch EA, Till JE (1963) The distribution of colony-forming cells among spleen colonies. J Cell Physiol 62:327–36PubMedCrossRefGoogle Scholar
  3. 3.
    Crittenden SL, Bernstein DS, Bachorik JL, Thompson BE et al (2002) A conserved RNA-binding protein controls germline stem cells in Caenorhabditis elegans. Nature 417(6889):660–3PubMedCrossRefGoogle Scholar
  4. 4.
    Unhavaithaya Y, Hao Y, Beyret E, Yin H et al (2009) MILI, a PIWI-interacting RNA-binding protein, is required for germ line stem cell self-renewal and appears to positively regulate translation. J Biol Chem 284(10):6507–19PubMedCrossRefGoogle Scholar
  5. 5.
    Okano H, Kawahara H, Toriya M, Nakao K et al (2005) Function of RNA-binding protein Musashi-1 in stem cells. Exp Cell Res 306(2):349–56PubMedCrossRefGoogle Scholar
  6. 6.
    Siddall NA, Kalcina M, Johanson TM, Monk AC et al (2012) Drosophila Rbp6 is an orthologue of vertebrate Msi-1 and Msi-2, but does not function redundantly with dMsi to regulate germline stem cell behaviour. PLoS One 7(11):e49810PubMedCrossRefGoogle Scholar
  7. 7.
    Akindahunsi AA, Bandiera A, Manzini G (2005) Vertebrate 2xRBD hnRNP proteins: a comparative analysis of genome, mRNA and protein sequences. Comput Biol Chem 29(1):13–23PubMedCrossRefGoogle Scholar
  8. 8.
    Good P, Yoda A, Sakakibara S, Yamamoto A et al (1998) The human Musashi homolog 1 (MSI1) gene encoding the homologue of Musashi/Nrp-1, a neural RNA-binding protein putatively expressed in CNS stem cells and neural progenitor cells. Genomics 52(3):382–4PubMedCrossRefGoogle Scholar
  9. 9.
    Nagata T, Kanno R, Kurihara Y, Uesugi S et al (1999) Structure, backbone dynamics and interactions with RNA of the C-terminal RNA-binding domain of a mouse neural RNA-binding protein, Musashi1. J Mol Biol 287(2):315–30PubMedCrossRefGoogle Scholar
  10. 10.
    Ohyama T, Furukawa A, Mashima T, Sugiyama T et al (2008) Structural analysis of Musashi-RNA complex on the basis of long-range structural information. Nucleic Acids Symp Ser (Oxf) 52:193–4CrossRefGoogle Scholar
  11. 11.
    Kawahara H, Imai T, Imataka H, Tsujimoto M et al (2008) Neural RNA-binding protein Musashi1 inhibits translation initiation by competing with eIF4G for PABP. J Cell Biol 181(4):639–53PubMedCrossRefGoogle Scholar
  12. 12.
    Gunter KM, McLaughlin EA (2011) Translational control in germ cell development: a role for the RNA-binding proteins Musashi-1 and Musashi-2. IUBMB Life 63(9):678–685PubMedGoogle Scholar
  13. 13.
    Okabe M, Imai T, Kurusu M, Hiromi Y et al (2001) Translational repression determines a neuronal potential in Drosophila asymmetric cell division. Nature 411(6833):94–8PubMedCrossRefGoogle Scholar
  14. 14.
    Hirota Y, Okabe M, Imai T, Kurusu M et al (1999) Musashi and seven in absentia downregulate Tramtrack through distinct mechanisms in Drosophila eye development. Mech Dev 87(1–2):93–101PubMedCrossRefGoogle Scholar
  15. 15.
    Sakakibara S, Imai T, Hamaguchi K, Okabe M et al (1996) Mouse-Musashi-1, a neural RNA-binding protein highly enriched in the mammalian CNS stem cell. Dev Biol 176(2):230–42PubMedCrossRefGoogle Scholar
  16. 16.
    Battelli C, Nikopoulos GN, Mitchell JG, Verdi JM (2006) The RNA-binding protein Musashi-1 regulates neural development through the translational repression of p21WAF-1. Mol Cell Neurosci 31(1):85–96PubMedCrossRefGoogle Scholar
  17. 17.
    Imai T, Tokunaga A, Yoshida T, Hashimoto M et al (2001) The neural RNA-binding protein Musashi1 translationally regulates mammalian numb gene expression by interacting with its mRNA. Mol Cell Biol 21(12):3888–900PubMedCrossRefGoogle Scholar
  18. 18.
    Horisawa K, Imai T, Okano H, Yanagawa H (2009) 3′-Untranslated region of doublecortin mRNA is a binding target of the Musashi1 RNA-binding protein. FEBS Lett 583(14):2429–34PubMedCrossRefGoogle Scholar
  19. 19.
    Charlesworth A, Wilczynska A, Thampi P, Cox LL et al (2006) Musashi regulates the temporal order of mRNA translation during Xenopus oocyte maturation. EMBO J 25(12):2792–801PubMedCrossRefGoogle Scholar
  20. 20.
    MacNicol AM, Wilczynska A, MacNicol MC (2008) Function and regulation of the mammalian Musashi mRNA translational regulator. Biochem Soc Trans 36(Pt 3):528–30PubMedCrossRefGoogle Scholar
  21. 21.
    Arumugam K, Wang Y, Hardy LL, MacNicol MC et al (2010) Enforcing temporal control of maternal mRNA translation during oocyte cell-cycle progression. EMBO J 29(2):387–97PubMedCrossRefGoogle Scholar
  22. 22.
    MacNicol MC, Cragle CE, MacNicol AM (2011) Context-dependent regulation of Musashi-mediated mRNA translation and cell cycle regulation. Cell Cycle 10(1):39–44PubMedCrossRefGoogle Scholar
  23. 23.
    Arumugam K, Macnicol M, Macnicol A (2012) Autoregulation of Musashi1 mRNA translation during Xenopus oocyte maturation. Mol Reprod Dev 79(8):553–563PubMedCrossRefGoogle Scholar
  24. 24.
    Kuwako K, Kakumoto K, Imai T, Igarashi M et al (2010) Neural RNA-binding protein Musashi1 controls midline crossing of precerebellar neurons through posttranscriptional regulation of Robo3/Rig-1 expression. Neuron 67(3):407–21PubMedCrossRefGoogle Scholar
  25. 25.
    de Sousa AR, Sanchez-Diaz PC, Vogel C, Burns SC et al (2009) Genomic analyses of musashi1 downstream targets show a strong association with cancer-related processes. J Biol Chem 284(18):12125–35CrossRefGoogle Scholar
  26. 26.
    Nikpour P, Baygi ME, Steinhoff C, Hader C et al (2011) The RNA binding protein Musashi1 regulates apoptosis, gene expression and stress granule formation in urothelial carcinoma cells. J Cell Mol Med 15(5):1210–24PubMedCrossRefGoogle Scholar
  27. 27.
    Sakakibara S, Nakamura Y, Yoshida T, Shibata S et al (2002) RNA-binding protein Musashi family: roles for CNS stem cells and a subpopulation of ependymal cells revealed by targeted disruption and antisense ablation. Proc Natl Acad Sci U S A 99(23):15194–9PubMedCrossRefGoogle Scholar
  28. 28.
    Kharas MG, Lengner CJ, Al-Shahrour F, Bullinger L et al (2010) Musashi-2 regulates normal hematopoiesis and promotes aggressive myeloid leukemia. Nat Med 16(8):903–8PubMedCrossRefGoogle Scholar
  29. 29.
    Ito T, Kwon HY, Zimdahl B, Congdon KL et al (2010) Regulation of myeloid leukaemia by the cell-fate determinant Musashi. Nature 466(7307):765–8PubMedCrossRefGoogle Scholar
  30. 30.
    Kawahara H, Okada Y, Imai T, Iwanami A et al (2011) Musashi1 cooperates in abnormal cell lineage protein 28 (Lin28)-mediated let-7 family microRNA biogenesis in early neural differentiation. J Biol Chem 286(18):16121–30PubMedCrossRefGoogle Scholar
  31. 31.
    Kawase S, Imai T, Miyauchi-Hara C, Yaguchi K et al (2011) Identification of a novel intronic enhancer responsible for the transcriptional regulation of musashi1 in neural stem/progenitor cells. Mol Brain 4:14PubMedCrossRefGoogle Scholar
  32. 32.
    Vo DT, Qiao M, Smith AD, Burns SC et al (2011) The oncogenic RNA-binding protein Musashi1 is regulated by tumor suppressor miRNAs. RNA Biol 8(5)Google Scholar
  33. 33.
    Nakamura M, Okano H, Blendy JA, Montell C (1994) Musashi, a neural RNA-binding protein required for Drosophila adult external sensory organ development. Neuron 13(1):67–81PubMedCrossRefGoogle Scholar
  34. 34.
    Siddall NA, Hime GR, Pollock JA, Batterham P (2009) Ttk69-dependent repression of lozenge prevents the ectopic development of R7 cells in the Drosophila larval eye disc. BMC Dev Biol 9:64PubMedCrossRefGoogle Scholar
  35. 35.
    Siddall NA, McLaughlin EA, Marriner NL, Hime GR (2006) The RNA-binding protein Musashi is required intrinsically to maintain stem cell identity. Proc Natl Acad Sci U S A 103(22):8402–7PubMedCrossRefGoogle Scholar
  36. 36.
    Yoda A, Sawa H, Okano H (2000) MSI-1, a neural RNA-binding protein, is involved in male mating behaviour in Caenorhabditis elegans. Genes Cells 5(11):885–95PubMedCrossRefGoogle Scholar
  37. 37.
    Kawashima T, Murakami AR, Ogasawara M, Tanaka K et al (2000) Expression patterns of Musashi homologs of the ascidians, Halocynthia roretzi and Ciona intestinalis. Dev Genes Evol 210(3):162–5PubMedCrossRefGoogle Scholar
  38. 38.
    Higuchi S, Hayashi T, Tarui H, Nishimura O et al (2008) Expression and functional analysis of musashi-like genes in planarian CNS regeneration. Mech Dev 125(7):631–45PubMedCrossRefGoogle Scholar
  39. 39.
    Kaneko Y, Sakakibara S, Imai T, Suzuki A et al (2000) Musashi1: an evolutionally conserved marker for CNS progenitor cells including neural stem cells. Dev Neurosci 22(1–2):139–53PubMedCrossRefGoogle Scholar
  40. 40.
    Shibata S, Umei M, Kawahara H, Yano M et al (2012) Characterization of the RNA-binding protein Musashi1 in Zebrafish. Brain Res 1462:162PubMedCrossRefGoogle Scholar
  41. 41.
    Toda M, Iizuka Y, Yu W, Imai T et al (2001) Expression of the neural RNA-binding protein Musashi1 in human gliomas. Glia 34(1):1–7PubMedCrossRefGoogle Scholar
  42. 42.
    Kong DS, Kim MH, Park WY, Suh YL et al (2008) The progression of gliomas is associated with cancer stem cell phenotype. Oncol Rep 19(3):639–43PubMedGoogle Scholar
  43. 43.
    Nakano A, Kanemura Y, Mori K, Kodama E et al (2007) Expression of the neural RNA-binding protein Musashi1 in pediatric brain tumors. Pediatr Neurosurg 43(4):279–84PubMedCrossRefGoogle Scholar
  44. 44.
    Kanemura Y, Sakakibara S, Okano H (2002) Identi-fication of Musashi1-positive cells in human normal and neoplastic neuroepithelial tissues by immunohistochemical methods. Methods Mol Biol 198:273–81PubMedGoogle Scholar
  45. 45.
    Kanemura Y, Mori K, Sakakibara S, Fujikawa H et al (2001) Musashi1, an evolutionarily conserved neural RNA-binding protein, is a versatile marker of human glioma cells in determining their cellular origin, malignancy, and proliferative activity. Differentiation 68(2–3):141–52PubMedCrossRefGoogle Scholar
  46. 46.
    Yen TH, Wright NA (2006) The gastrointestinal tract stem cell niche. Stem Cell Rev 2(3):203–12PubMedCrossRefGoogle Scholar
  47. 47.
    Yuqi L, Chengtang W, Ying W, Shangtong L et al (2008) The expression of Msi-1 and its significance in small intestinal mucosa severely damaged by high-dose 5-FU. Dig Dis Sci 53(9):2436–42PubMedCrossRefGoogle Scholar
  48. 48.
    Potten CS, Booth C, Tudor GL, Booth D et al (2003) Identification of a putative intestinal stem cell and early lineage marker; Musashi-1. Differentiation 71(1):28–41PubMedCrossRefGoogle Scholar
  49. 49.
    He XC, Yin T, Grindley JC, Tian Q et al (2007) PTEN-deficient intestinal stem cells initiate intestinal polyposis. Nat Genet 39(2):189–98PubMedCrossRefGoogle Scholar
  50. 50.
    Montgomery RK, Breault DT (2008) Small intestinal stem cell markers. J Anat 213(1):52–8PubMedCrossRefGoogle Scholar
  51. 51.
    Samuel S, Walsh R, Webb J, Robins A et al (2009) Characterization of putative stem cells in isolated human colonic crypt epithelial cells and their interactions with myofibroblasts. Am J Physiol Cell Physiol 296(2):C296–C305PubMedCrossRefGoogle Scholar
  52. 52.
    George RJ, Sturmoski MA, May R, Sureban SM et al (2009) Loss of p21Waf1/Cip1/Sdi1 enhances intestinal stem cell survival following radiation injury. Am J Physiol Gastrointest Liver Physiol 296(2):G245–G54254PubMedCrossRefGoogle Scholar
  53. 53.
    Murata H, Tsuji S, Tsujii M, Nakamura T et al (2008) Helicobacter pylori infection induces candidate stem cell marker Musashi-1 in the human gastric epithelium. Dig Dis Sci 53(2):363–9PubMedCrossRefGoogle Scholar
  54. 54.
    Nagata H, Akiba Y, Suzuki H, Okano H et al (2006) Expression of Musashi-1 in the rat stomach and changes during mucosal injury and restitution. FEBS Lett 580(1):27–33PubMedCrossRefGoogle Scholar
  55. 55.
    Bobryshev YV, Freeman AK, Botelho NK, Tran D et al (2010) Expression of the putative stem cell marker Musashi-1 in Barrett’s esophagus and esophageal adenocarcinoma. Dis Esophagus 23(7):580–9PubMedCrossRefGoogle Scholar
  56. 56.
    Wang T, Ong CW, Shi J, Srivastava S et al (2011) Sequential expression of putative stem cell markers in gastric carcinogenesis. Br J Cancer 105(5):658–65PubMedCrossRefGoogle Scholar
  57. 57.
    Burkert J, Otto WR, Wright NA (2008) Side populations of gastrointestinal cancers are not enriched in stem cells. J Pathol 214(5):564–73PubMedCrossRefGoogle Scholar
  58. 58.
    Sureban SM, May R, George RJ, Dieckgraefe BK et al (2008) Knockdown of RNA binding protein musashi-1 leads to tumor regression in vivo. Gastroenterology 134(5):1448–58PubMedCrossRefGoogle Scholar
  59. 59.
    Gotte M, Wolf M, Staebler A, Buchweitz O et al (2008) Increased expression of the adult stem cell marker Musashi-1 in endometriosis and endometrial carcinoma. J Pathol 215(3):317–29PubMedCrossRefGoogle Scholar
  60. 60.
    Wang XY, Yin Y, Yuan H, Sakamaki T et al (2008) Musashi1 modulates mammary progenitor cell expansion through proliferin-mediated activation of the Wnt and Notch pathways. Mol Cell Biol 28(11):3589–99PubMedCrossRefGoogle Scholar
  61. 61.
    Wang XY, Penalva LO, Yuan H, Linnoila RI et al (2010) Musashi1 regulates breast tumor cell proliferation and is a prognostic indicator of poor survival. Mol Cancer 9:221PubMedCrossRefGoogle Scholar
  62. 62.
    Glazer RI, Wang XY, Yuan H, Yin Y (2008) Musashi1: a stem cell marker no longer in search of a function. Cell Cycle 7(17):2635–9PubMedCrossRefGoogle Scholar
  63. 63.
    Kagara N, Huynh K, Kuo C, Okano H et al (2012) Epigenetic regulation of cancer stem cell genes in triple-negative breast cancer. Am J Pathol 181(1):257PubMedCrossRefGoogle Scholar
  64. 64.
    Götte M, Greve B, Kelsch R, Müller-Uthoff H et al (2011) The adult stem cell marker Musashi-1 modulates endometrial carcinoma cell cycle progression and apoptosis via Notch-1 and p21 (WAF1/CIP1). Int J Cancer J Int du Cancer 129(8):2042CrossRefGoogle Scholar
  65. 65.
    Sakakibara S, Okano H (1997) Expression of neural RNA-binding proteins in the postnatal CNS: implications of their roles in neuronal and glial cell development. J Neurosci 17(21):8300–12PubMedGoogle Scholar
  66. 66.
    Sakakibara S, Nakamura Y, Satoh H, Okano H (2001) Rna-binding protein Musashi2: developmentally regulated expression in neural precursor cells and subpopulations of neurons in mammalian CNS. J Neurosci 21(20):8091–107PubMedGoogle Scholar
  67. 67.
    Wuebben E, Mallanna S, Cox J, Rizzino A (2012) Musashi2 is required for the self-renewal and pluripotency of embryonic stem cells. PLoS One 7(4):e34827PubMedCrossRefGoogle Scholar
  68. 68.
    Lemieux ME, Cheng Z, Zhou Q, White R et al (2011) Inactivation of a single copy of Crebbp selectively alters pre-mRNA processing in mouse hematopoietic stem cells. PLoS One 6(8):e24153PubMedCrossRefGoogle Scholar
  69. 69.
    de Andres-Aguayo L, Varas F, Kallin EM, Infante JF et al (2011) Musashi 2 is a regulator of the HSC compartment identified by a retroviral insertion screen and knockout mice. Blood 118(3):554–64PubMedCrossRefGoogle Scholar
  70. 70.
    Nishimoto Y, Okano H (2010) New insight into cancer therapeutics: induction of differentiation by regulating the Musashi/Numb/Notch pathway. Cell Res 20(10):1083–5PubMedCrossRefGoogle Scholar
  71. 71.
    Hope KJ, Sauvageau G (2011) Roles for MSI2 and PROX1 in hematopoietic stem cell activity. Curr Opin Hematol 18(4):203–7PubMedCrossRefGoogle Scholar
  72. 72.
    Griner LN, Reuther GW (2010) Aggressive myeloid leukemia formation is directed by the Musashi 2/Numb pathway. Cancer Biol Ther 10(10):979–82PubMedCrossRefGoogle Scholar
  73. 73.
    Barbouti A, Hoglund M, Johansson B, Lassen C et al (2003) A novel gene, MSI2, encoding a putative RNA-binding protein is recurrently rearranged at disease progression of chronic myeloid leukemia and forms a fusion gene with HOXA9 as a result of the cryptic t(7;17)(p15;q23). Cancer Res 63(6):1202–6PubMedGoogle Scholar
  74. 74.
    De Weer A, Speleman F, Cauwelier B, Van Roy N et al (2008) EVI1 overexpression in t(3;17) positive myeloid malignancies results from juxtaposition of EVI1 to the MSI2 locus at 17q22. Haematologica 93(12):1903–7PubMedCrossRefGoogle Scholar
  75. 75.
    De Weer A, Poppe B, Cauwelier B, Carlier A et al (2008) EVI1 activation in blast crisis CML due to juxtaposition to the rare 17q22 partner region as part of a 4-way variant translocation t(9;22). BMC Cancer 8:193PubMedCrossRefGoogle Scholar
  76. 76.
    Danovi SA (2010) Leukaemia: comfortably MSI2-NUMB. Nat Rev Cancer 10(9):602PubMedCrossRefGoogle Scholar
  77. 77.
    Byers RJ, Currie T, Tholouli E, Rodig SJ et al (2011) MSI2 protein expression predicts unfavorable outcome in acute myeloid leukemia. Blood 118(10):2857–67PubMedCrossRefGoogle Scholar
  78. 78.
    de Andrés-Aguayo L, Varas F, Graf T (2012) Musashi 2 in hematopoiesis. Curr Opin Hematol 19(4):268PubMedCrossRefGoogle Scholar

Copyright information

© Springer Science+Business Media Dordrecht 2013

Authors and Affiliations

  • Jessie M. Sutherland
    • 1
  • Eileen A. McLaughlin
    • 1
    Email author
  • Gary R. Hime
    • 2
  • Nicole A. Siddall
    • 2
  1. 1.Priority Research Centre in Reproductive Science, School of Environmental and Life SciencesUniversity of NewcastleCallaghanAustralia
  2. 2.Department of Anatomy and NeuroscienceUniversity of MelbourneParkville, MelbourneAustralia

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