Transcription regulator LMO4 interferes with neuritogenesis in human SH-SY5Y neuroblastoma cells.
LMO4 is a transcription regulator interacting with proteins involved, among else, in tumorigenesis. Its function in the nervous system, and particularly in the adult nervous system, has however still to be elucidated. We decided to modify its expression in a neuronal model, human SH-SY5Y neuroblastoma cells, by permanent transfection of sense or anti-sense Lmo4 cDNAs. Generated clones overexpressing the Lmo4 transcript in sense orientation tended to aggregate. They showed significantly reduced average number of neurites per cell and average neuritic length per cell. The opposite was observed with clones overexpressing the anti-sense Lmo4 transcript. Furthermore, selected clones were subjected to 72 h long-term treatments with retinoic acid and phorbol ester (TPA), two biochemicals known to stimulate differentiation of non-transfected SH-SY5Y cells and other neuroblastoma cells. Neuritogenesis occurred after retinoic acid stimulation in all cases. The inhibitory effect of sense Lmo4 RNA overexpression on neuritic outgrowth was indeed prevented. The protein kinase C activator TPA could not induce neuritogenesis in SH-SY5Y cells overexpressing sense Lmo4 RNA. Thus, sense Lmo4 RNA overexpression, not Lmo4 endogenous transcription, overrides the stimulatory effect of TPA upon neuritic outgrowth. We also showed that Lmo4-dependent neuritic retraction and outgrowth correspond to altered phosphorylation of cytoskeletal proteins. Overall, Lmo4 RNA overexpression interferes with neuritic outgrowth, whereas anti-sense Lmo4 RNA expression favors neuritogenesis in SH-SY5Y cells. Consequently, changes in Lmo4 RNA expression levels might alter the rate of neuritic outgrowth in the developing and adult nervous system.
Vu
Dung
D
Department of Psychiatry, University of Geneva School of Medicine, CH-1225, Geneva, Switzerland.
Marin
Pascale
P
Walzer
Claude
C
Cathieni
Maria Margherita
MM
Bianchi
Estelle N
EN
Saïdji
Farouk
F
Leuba
Geneviève
G
Bouras
Constantin
C
Savioz
Armand
A
D048868:Adaptor Proteins, Signal Transducing; D000970:Antineoplastic Agents / Q000494:pharmacology; D015153:Blotting, Western / Q000379:methods; D002273:Carcinogens / Q000494:pharmacology; D002449:Cell Aggregation / Q000187:drug effects / Q000235:genetics / Q000502:physiology; D002454:Cell Differentiation / Q000187:drug effects / Q000502:physiology; D002460:Cell Line; D003001:Cloning, Molecular; D003598:Cytoskeletal Proteins / Q000378:metabolism; D015870:Gene Expression / Q000502:physiology; D018398:Homeodomain Proteins / Q000235:genetics / Q000502:physiology*; D006801:Humans; D060588:LIM Domain Proteins; D008959:Models, Neurological; D016501:Neurites / Q000187:drug effects / Q000502:physiology*; D009447:Neuroblastoma / Q000473:pathology; D010703:Phorbol Esters / Q000494:pharmacology; D012322:RNA Precursors / Q000502:physiology*; D016372:RNA, Antisense / Q000378:metabolism; D012333:RNA, Messenger / Q000096:biosynthesis; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000379:methods; D014157:Transcription Factors / Q000235:genetics / Q000502:physiology*; D014162:Transfection / Q000379:methods; D014212:Tretinoin / Q000494:pharmacology; D014407:Tumor Cells, Cultured
D048868:Adaptor Proteins, Signal Transducing; D000970:Antineoplastic Agents; D002273:Carcinogens; D003598:Cytoskeletal Proteins; D018398:Homeodomain Proteins; D060588:LIM Domain Proteins; C114905:LMO4 protein, human; D010703:Phorbol Esters; D012322:RNA Precursors; D016372:RNA, Antisense; D012333:RNA, Messenger; D014157:Transcription Factors; D014212:Tretinoin