SC35 promotes sustainable stress-induced alternative splicing of neuronal acetylcholinesterase mRNA

Abstract

Long-lasting alternative splicing of neuronal acetylcholinesterase (AChE) pre-mRNA occurs during neuronal development and following stress, altering synaptic properties. To explore the corresponding molecular events, we sought to identify mRNAs encoding for abundant splicing factors in the prefrontal cortex (PFC) following stress. Here we show elevated levels of the splicing factor SC35 in stressed as compared with naïve mice. In cotransfections of COS-1 and HEK293 cells with an AChE minigene allowing 3 0 splice variations, SC35 facilitated a shift from the primary AChE-S to the stress-induced AChE-R variant, while ASF/SF2 caused the opposite effect. Transfection with chimeric constructs comprising of SC35 and ASF/SF2 RRM/RS domains identified the SC35 RRM as responsible for AChE mRNA's alternative splicing. In poststress PFC neurons, increased SC35 mRNA and protein levels coincided with selective increase in AChE-R mRNA. In the developing mouse embryo, cortical progenitor cells in the ventricular zone displayed transient SC35 elevation concomitant with dominance of AChE-R over AChE-S mRNA. Finally, transgenic mice overexpressing human AChE-R, but not those overexpressing AChE-S, showed significant elevation in neuronal SC35 levels, suggesting a reciprocal reinforcement process. Together, these findings point to an interactive relationship of SC35 with cholinergic signals in the long-lasting consequences of stress on nervous system plasticity and development. Molecular Psychiatry (2005) 10, 985-997.

Quantitative and evolutionary biology of alternative splicing: how changing the mix of alternative transcripts affects phenotypic plasticity and reaction norms

“…Mice exposed to mild stress, and transgenic mice overexpressing AChE-R, show fearful behavioral traits such as delayed willingness to emerge from a box into an open field. The AChE-R isoform also increases expression of the splicing factor (SC35) that favors AChE-R transcript formation, Alternative splicing and phenotypic plasticity JH Marden thereby forming a positive feedback loop that may be the mechanism underlying the prolonged behavioral impact of acute stress (Meshorer et al, 2005).…”

Acetylcholinesterase/C terminal binding protein interactions modify Ikaros functions, causing T lymphopenia

“…Under stress, AChE-S is substituted with AChE-R. 10 Consequent myelopoiesis could be solely due to AChE-R's capacity to upregulate hematopoiesis. 9 Alternatively, the decrease in AChE-S could also be actively involved, by avoiding negative regulatory function(s).…”

“…Under stress, an S-to-R shift suppresses the levels of the nuclearly targeted AChE-S protein and its ASP C terminus. 10 (b) The CtBP 2 amino-acid sequence. The ASP 67 -binding domain is highlighted.…”

“…11 Vectors AChE-S under cytomegalovirus (CMV) control and fusion proteins of GFP and AChE C-terminal peptides were as described. 10,18 For luciferase assays, we used the pcDNA3.Gal4 DBD (activating the reporter gene), pcDNA3.mCtBP2 (encoding murine CtBP2) and pcDNA3.Gal4DBD.Ikaros1-81, encoding Gal4 DBD fused to the CtBP-interacting region of Ikaros (Ik1-81), 19,20 all a kind gift from Dr M Crossley (Sydney, Australia). The firefly luciferase reporter vector, pGL2(Gal4) 5 TK, contained five copies of the Gal4 DBD upstream of the TK promoter in the vector pGL2-TK (Promega, Madison, WI, USA).…”

“…Multiple stress stimuli involve increased ratio between AChE-R and AChE-S in brain and blood cells alike. 9,10 AChE-R interacts with the intracellular scaffold protein RACK1 and its protein kinase C (PKC) partner through its C-terminal peptide, ARP. 11 In hematopoietic cells, this induces myelopoiesis.…”