A positive feedback mechanism that regulates expression of miR-9 during neurogenesis.
MiR-9, a neuron-specific miRNA, is an important regulator of neurogenesis. In this study we identify how miR-9 is regulated during early differentiation from a neural stem-like cell. We utilized two immortalized rat precursor clones, one committed to neurogenesis (L2.2) and another capable of producing both neurons and non-neuronal cells (L2.3), to reproducibly study early neurogenesis. Exogenous miR-9 is capable of increasing neurogenesis from L2.3 cells. Only one of three genomic loci capable of encoding miR-9 was regulated during neurogenesis and the promoter region of this locus contains sufficient functional elements to drive expression of a luciferase reporter in a developmentally regulated pattern. Furthermore, among a large number of potential regulatory sites encoded in this sequence, Mef2 stood out because of its known pro-neuronal role. Of four Mef2 paralogs, we found only Mef2C mRNA was regulated during neurogenesis. Removal of predicted Mef2 binding sites or knockdown of Mef2C expression reduced miR-9-2 promoter activity. Finally, the mRNA encoding the Mef2C binding partner HDAC4 was shown to be targeted by miR-9. Since HDAC4 protein could be co-immunoprecipitated with Mef2C protein or with genomic Mef2 binding sequences, we conclude that miR-9 regulation is mediated, at least in part, by Mef2C binding but that expressed miR-9 has the capacity to reduce inhibitory HDAC4, stabilizing its own expression in a positive feedback mechanism.
W.M. Keck Center for Collaborative Neuroscience and the Department of Cell Biology and Neuroscience, Rutgers University, Piscataway, New Jersey, United States of America.
Jonathan L
JL
Davila
W.M. Keck Center for Collaborative Neuroscience and the Department of Cell Biology and Neuroscience, Rutgers University, Piscataway, New Jersey, United States of America.
Loyal A
LA
Goff
W.M. Keck Center for Collaborative Neuroscience and the Department of Cell Biology and Neuroscience, Rutgers University, Piscataway, New Jersey, United States of America.
Christopher L
CL
Ricupero
W.M. Keck Center for Collaborative Neuroscience and the Department of Cell Biology and Neuroscience, Rutgers University, Piscataway, New Jersey, United States of America.
Cynthia
C
Camarillo
W.M. Keck Center for Collaborative Neuroscience and the Department of Cell Biology and Neuroscience, Rutgers University, Piscataway, New Jersey, United States of America.
Eileen N
EN
Oni
W.M. Keck Center for Collaborative Neuroscience and the Department of Cell Biology and Neuroscience, Rutgers University, Piscataway, New Jersey, United States of America.
Mavis R
MR
Swerdel
W.M. Keck Center for Collaborative Neuroscience and the Department of Cell Biology and Neuroscience, Rutgers University, Piscataway, New Jersey, United States of America.
Alana J
AJ
Toro-Ramos
W.M. Keck Center for Collaborative Neuroscience and the Department of Cell Biology and Neuroscience, Rutgers University, Piscataway, New Jersey, United States of America.
Jiali
J
Li
W.M. Keck Center for Collaborative Neuroscience and the Department of Cell Biology and Neuroscience, Rutgers University, Piscataway, New Jersey, United States of America.
Ronald P
RP
Hart
D020413:3' Untranslated Regions; D000818:Animals; D001483:Base Sequence; D001665:Binding Sites; D002454:Cell Differentiation / Q000235:genetics; D002461:Cell Line, Transformed; D025461:Feedback, Physiological; D018507:Gene Expression Regulation, Developmental; D006655:Histone Deacetylases / Q000235:genetics / Q000378:metabolism; D064326:MEF2 Transcription Factors / Q000235:genetics / Q000378:metabolism; D035683:MicroRNAs / Q000235:genetics*; D058953:Neural Stem Cells / Q000166:cytology / Q000378:metabolism; D055495:Neurogenesis / Q000502:physiology*; D009474:Neurons / Q000166:cytology / Q000378:metabolism; D011401:Promoter Regions, Genetic; D011485:Protein Binding; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D051381:Rats; D014158:Transcription, Genetic
D020413:3' Untranslated Regions; D064326:MEF2 Transcription Factors; C582333:MIRN9 microRNA, rat; D035683:MicroRNAs; D012333:RNA, Messenger; C559944:HDAC4 protein, rat; D006655:Histone Deacetylases