Neuronal ELAV proteins enhance mRNA stability by a PKCalpha-dependent pathway.
More than 1 in 20 human genes bear in the mRNA 3' UTR a specific motif called the adenine- and uridine-rich element (ARE), which posttranscriptionally determines its expression in response to cell environmental signals. ELAV (embryonic lethal abnormal vision) proteins are the only known ARE-binding factors that are able to stabilize the bound mRNAs, thereby positively controlling gene expression. Here, we show that in human neuroblastoma SH-SY5Y cells, neuron-specific ELAV (nELAV) proteins (HuB, HuC, and HuD) are up-regulated and redistributed by 15 min of treatment with the activators of PKC phorbol esters and bryostatin-1. PKC stimulation also induces nELAV proteins to colocalize with the translocated PKCalpha isozyme preferentially on the cytoskeleton, with a concomitant increase of nELAV threonine phosphorylation. The same treatment promotes stabilization of growth-associated protein 43 (GAP-43) mRNA, a well known nELAV target, and induces an early increase in GAP-43 protein concentration, again only in the cytoskeletal cell fraction. Genetic or pharmacological inactivation of PKCalpha abolishes nELAV protein cytoskeletal up-regulation, GAP-43 mRNA stabilization, and GAP-43 protein increase, demonstrating the primary role of this specific PKC isozyme in the cascade of nELAV recruitment. Finally, in vivo PKC activation is associated with an up-regulation of nELAV proteins in the hippocampal rat brain. These findings suggest a model for gene expression regulation by nELAV proteins through a PKCalpha-dependent pathway that is relevant for the cellular programs in which ARE-mediated control plays a pivotal role.
Pascale
Alessia
A
Department of Experimental and Applied Pharmacology, University of Pavia, Via Taramelli 14, 27100 Pavia, Italy. alessia.pascale@unipv.it
Amadio
Marialaura
M
Scapagnini
Giovanni
G
Lanni
Cristina
C
Racchi
Marco
M
Provenzani
Alessandro
A
Govoni
Stefano
S
Alkon
Daniel L
DL
Quattrone
Alessandro
A
D020413:3' Untranslated Regions / Q000378:metabolism; D020816:Amino Acid Motifs / Q000502:physiology; D000818:Animals; D015153:Blotting, Western; D054713:Bryostatins; D045744:Cell Line, Tumor; D003599:Cytoskeleton / Q000378:metabolism; D017931:DNA Primers; D051959:ELAV Proteins / Q000378:metabolism*; D019922:GAP-43 Protein / Q000378:metabolism; D005786:Gene Expression Regulation / Q000187:drug effects / Q000502:physiology*; D006624:Hippocampus / Q000378:metabolism; D006801:Humans; D007150:Immunohistochemistry; D047468:Immunoprecipitation; D018942:Macrolides / Q000494:pharmacology; D009474:Neurons / Q000378:metabolism*; D010703:Phorbol Esters / Q000494:pharmacology; D051571:Protein Kinase C-alpha / Q000378:metabolism*; D020871:RNA Stability / Q000502:physiology*; D012333:RNA, Messenger / Q000378:metabolism*; D051381:Rats; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction / Q000502:physiology*
D020413:3' Untranslated Regions; D054713:Bryostatins; D017931:DNA Primers; D051959:ELAV Proteins; D019922:GAP-43 Protein; D018942:Macrolides; D010703:Phorbol Esters; D012333:RNA, Messenger; C046785:bryostatin 1; D051571:Protein Kinase C-alpha