Transcriptional regulation of human MAP2 gene in melanoma: role of neuronal bHLH factors and Notch1 signaling.
Microtubule-associated protein 2 (MAP2), a neuron-specific protein, stabilizes microtubules and is critical for neurite outgrowth and dendrite development. Although MAP2 is widely used as a marker of neuronal differentiation, regulation of its transcription has not been investigated. We showed that MAP2 is frequently activated in human cutaneous melanoma. Here, we identified a 2.2 kb region that is sufficient for neuronal-specific expression in vitro and in vivo. Comparative analysis of the mouse, rat and human MAP2 promoter sequences showed the presence of a conserved bHLH factor binding sites. Electrophoretic mobility shift analysis, promoter mutagenesis and co-transfection experiments showed that NeuroD, a pro-neuronal differentiation factor, and Hairy and Enhancer of Split (HES1), a transcription repressor, are involved in the regulation of MAP2 promoter activity. Melanoma cells express both NeuroD and HES1. Chromatin immunoprecipitation showed that in metastatic melanoma cells N-box region of the MAP2 promoter is occupied by endogenous HES1. We show that the inhibition of Notch signaling, a regulator of HES1 gene expression, and/or shRNA knockdown of HES1 results in the upregulation of MAP2 promoter activity. Thus, our data suggest that Notch signaling, which is implicated in melanoma progression, and HES1 play a role in MAP2 gene regulation during melanoma progression.
Bhat
Kumar M R
KM
Department of Dermatology, University of Wisconsin, 1300 University Avenue, B25, Madison, WI 53706, USA.
Maddodi
Nityanand
N
Shashikant
Cooduvalli
C
Setaluri
Vijayasaradhi
V
D000818:Animals; D001483:Base Sequence; D051792:Basic Helix-Loop-Helix Proteins / Q000378:metabolism*; D001665:Binding Sites; D045744:Cell Line, Tumor; D017124:Conserved Sequence; D015972:Gene Expression Regulation, Neoplastic; D006367:HeLa Cells; D018398:Homeodomain Proteins / Q000378:metabolism; D006801:Humans; D008545:Melanoma / Q000235:genetics* / Q000378:metabolism; D051379:Mice; D008869:Microtubule-Associated Proteins / Q000235:genetics*; D009419:Nerve Tissue Proteins / Q000378:metabolism; D016716:PC12 Cells; D011401:Promoter Regions, Genetic; D051381:Rats; D051881:Receptor, Notch1 / Q000378:metabolism*; D012097:Repressor Proteins / Q000378:metabolism; D015398:Signal Transduction; D000072056:Transcription Factor HES-1; D015533:Transcriptional Activation
D051792:Basic Helix-Loop-Helix Proteins; D018398:Homeodomain Proteins; D008869:Microtubule-Associated Proteins; D009419:Nerve Tissue Proteins; D051881:Receptor, Notch1; D012097:Repressor Proteins; D000072056:Transcription Factor HES-1; C489734:Hes1 protein, mouse; C489788:MAP2 protein, human; C093564:Neurogenic differentiation factor 1