title: Effects of IKAP/hELP1 deficiency on gene expression in differentiating neuroblastoma cells: implications for familial dysautonomia.
abstract: Familial dysautonomia (FD) is a developmental neuropathy of the sensory and autonomous nervous systems. The IKBKAP gene, encoding the IKAP/hELP1 subunit of the RNA polymerase II Elongator complex is mutated in FD patients, leading to a tissue-specific mis-splicing of the gene and to the absence of the protein in neuronal tissues. To elucidate the function of IKAP/hELP1 in the development of neuronal cells, we have downregulated IKBKAP expression in SHSY5Y cells, a neuroblastoma cell line of a neural crest origin. We have previously shown that these cells exhibit abnormal cell adhesion when allowed to differentiate under defined culture conditions on laminin substratum. Here, we report results of a microarray expression analysis of IKAP/hELP1 downregulated cells that were grown on laminin under differentiation or non-differentiation growth conditions. It is shown that under non-differentiation growth conditions, IKAP/hELP1 downregulation affects genes important for early developmental stages of the nervous system, including cell signaling, cell adhesion and neural crest migration. IKAP/hELP1 downregulation during differentiation affects the expression of genes that play a role in late neuronal development, in axonal projection and synapse formation and function. We also show that IKAP/hELP1 deficiency affects the expression of genes involved in calcium metabolism before and after differentiation of the neuroblastoma cells. Hence, our data support IKAP/hELP1 importance in the development and function of neuronal cells and contribute to the understanding of the FD phenotype.
authors.affiliation: Department of Cell Research and Immunology, Tel Aviv University, Ramat-Aviv, Israel.
authors.forename: Rachel
authors.initials: R
authors.lastname: Cohen-Kupiec
authors.forename: Metsada
authors.initials: M
authors.lastname: Pasmanik-Chor
authors.forename: Varda
authors.initials: V
authors.lastname: Oron-Karni
authors.forename: Miguel
authors.initials: M
authors.lastname: Weil
mesh_terms: D002118:Calcium / Q000378:metabolism; D002352:Carrier Proteins / Q000235:genetics* / Q000502:physiology*; D002448:Cell Adhesion; D002454:Cell Differentiation; D002465:Cell Movement; D004402:Dysautonomia, Familial / Q000235:genetics*; D020869:Gene Expression Profiling; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D009432:Neural Crest / Q000378:metabolism; D009447:Neuroblastoma / Q000235:genetics / Q000378:metabolism*; D012319:RNA Polymerase II / Q000378:metabolism; D015398:Signal Transduction; D035602:Transcriptional Elongation Factors
chemical_list: D002352:Carrier Proteins; C114720:Elp1 protein, human; D035602:Transcriptional Elongation Factors; D012319:RNA Polymerase II; D002118:Calcium