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Gene Review

Mnx1  -  motor neuron and pancreas homeobox 1

Mus musculus

Synonyms: HB9, Hlxb9, Homeobox protein HB9, MNR2, Motor neuron and pancreas homeobox protein 1
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Disease relevance of Hlxb9


High impact information on Hlxb9

  • Thus, Hlxb9 is key to normal pancreas development and function [2].
  • During mouse development, the dorsal and ventral pancreatic buds and mature beta-cells in the islets of Langerhans express Hlxb9 [2].
  • In absence of Hlxb9 expression, the dorsal region of the gut epithelium fails to initiate a pancreatic differentiation program [3].
  • Thus, dorsally Hlxb9 is required for specifying the gut epithelium to a pancreatic fate and ventrally for ensuring proper endocrine cell differentiation [3].
  • Presumptive MN progenitors and postmitotic MNs express HB9, whereas only a small population of interneurons located ventrally to the central canal express this factor [4] [5].

Biological context of Hlxb9

  • The homeobox gene Hlxb9, which is essential for the initiation of the pancreatic program in the dorsal foregut endoderm, is still expressed in Raldh2--/-- dorsal epithelium but the number of HB9-expressing cells is severely reduced [6].
  • In contrast, simultaneous transfection of Ngn2 and HB9 cDNA increased the expression of Isl1/2, a motoneuron marker, when the cells were maintained in medium supplemented with retinoic acid, forskolin, and sonic hedgehog [7].
  • In the transgenic mice used in our study, the HB9 promotor controlled the expression of the reporter gene enhanced green fluorescent protein (eGFP), giving rise to GFP+ motoneurons and ventral interneurons [8].
  • These results indicate that HB9 protein might be involved in chick tarsometatarsal scale and feather development and that nuclear import of HB9 protein might be regulated by these NLS sequences in the homeodomain [9].
  • ES cells were obtained from a transgenic mouse line in which the gene for enhanced green fluorescent protein (eGFP) is expressed under the control of the promotor of the MN specific homeobox gene Hb9 [10].

Anatomical context of Hlxb9


Associations of Hlxb9 with chemical compounds


Other interactions of Hlxb9

  • 5. At earlier stages, only a dorsal bud rudiment forms transiently and expresses the transcription factors Ipf1 and Hlxb9 but lacks the key transcription factor involved in the acquisition of a pancreatic fate, Ptf1a, as well as all endocrine precursor cells [13].
  • We showed that all these factors were present in neural progenitors derived from mouse ES cells, whereas NSCs derived from the rat embryonic spinal cord expressed neither HB9 nor Islet1 and contained low levels of Nkx6.1 and LIM3 [1].
  • NSFCs transfected with Olig2, Ngn2, and HB9 alone exhibited no phenotypic lineage restriction [7].

Analytical, diagnostic and therapeutic context of Hlxb9



  1. Forced expression of the motor neuron determinant HB9 in neural stem cells affects neurogenesis. Bréjot, T., Blanchard, S., Hocquemiller, M., Haase, G., Liu, S., Nosjean, A., Heard, J.M., Bohl, D. Exp. Neurol. (2006) [Pubmed]
  2. Pancreas dorsal lobe agenesis and abnormal islets of Langerhans in Hlxb9-deficient mice. Harrison, K.A., Thaler, J., Pfaff, S.L., Gu, H., Kehrl, J.H. Nat. Genet. (1999) [Pubmed]
  3. Selective agenesis of the dorsal pancreas in mice lacking homeobox gene Hlxb9. Li, H., Arber, S., Jessell, T.M., Edlund, H. Nat. Genet. (1999) [Pubmed]
  4. Conditional rhythmicity of ventral spinal interneurons defined by expression of the Hb9 homeodomain protein. Wilson, J.M., Hartley, R., Maxwell, D.J., Todd, A.J., Lieberam, I., Kaltschmidt, J.A., Yoshida, Y., Jessell, T.M., Brownstone, R.M. J. Neurosci. (2005) [Pubmed]
  5. Active suppression of interneuron programs within developing motor neurons revealed by analysis of homeodomain factor HB9. Thaler, J., Harrison, K., Sharma, K., Lettieri, K., Kehrl, J., Pfaff, S.L. Neuron (1999) [Pubmed]
  6. Dorsal pancreas agenesis in retinoic acid-deficient Raldh2 mutant mice. Martín, M., Gallego-Llamas, J., Ribes, V., Kedinger, M., Niederreither, K., Chambon, P., Dollé, P., Gradwohl, G. Dev. Biol. (2005) [Pubmed]
  7. Role of transcription factors in motoneuron differentiation of adult human olfactory neuroepithelial-derived progenitors. Zhang, X., Cai, J., Klueber, K.M., Guo, Z., Lu, C., Winstead, W.I., Qiu, M., Roisen, F.J. Stem Cells (2006) [Pubmed]
  8. Locomotor-like rhythms in a genetically distinct cluster of interneurons in the mammalian spinal cord. Hinckley, C.A., Hartley, R., Wu, L., Todd, A., Ziskind-Conhaim, L. J. Neurophysiol. (2005) [Pubmed]
  9. Localization of HB9 homeodomain protein and characterization of its nuclear localization signal during chick embryonic skin development. Kosaka, Y., Akimoto, Y., Yokozawa, K., Obinata, A., Hirano, H. Histochem. Cell Biol. (2004) [Pubmed]
  10. Functional properties of motoneurons derived from mouse embryonic stem cells. Miles, G.B., Yohn, D.C., Wichterle, H., Jessell, T.M., Rafuse, V.F., Brownstone, R.M. J. Neurosci. (2004) [Pubmed]
  11. Persistent expression of Hlxb9 in the pancreatic epithelium impairs pancreatic development. Li, H., Edlund, H. Dev. Biol. (2001) [Pubmed]
  12. Requirement for the homeobox gene Hb9 in the consolidation of motor neuron identity. Arber, S., Han, B., Mendelsohn, M., Smith, M., Jessell, T.M., Sockanathan, S. Neuron (1999) [Pubmed]
  13. Lack of TCF2/vHNF1 in mice leads to pancreas agenesis. Haumaitre, C., Barbacci, E., Jenny, M., Ott, M.O., Gradwohl, G., Cereghini, S. Proc. Natl. Acad. Sci. U.S.A. (2005) [Pubmed]
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