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Translational control of nicotine-evoked synaptic potentiation in mice and neuronal responses in human smokers by eIF2α

  1. Andon N Placzek
  2. David L Molfese
  3. Sanjeev Khatiwada
  4. Gonzalo Viana Di Prisco
  5. Wei Huang
  6. Carmela Sidrauski
  7. Krešimir Krnjević
  8. Christopher L Amos
  9. Russell Ray
  10. John A Dani
  11. Peter Walter
  12. Ramiro Salas
  13. Mauro Costa-Mattioli  Is a corresponding author
  1. Baylor College of Medicine, United States
  2. Michael E. DeBakey Veteran Administration Medical Center, United States
  3. Howard Hughes Medical Institute, University of California, San Francisco, United States
  4. McGill University, Canada
  5. Dartmouth College, United States
  6. Perelman School of Medicine, United States
Short Report
Cite this article as: eLife 2016;5:e12056 doi: 10.7554/eLife.12056
2 figures

Figures

Figure 1 with 1 supplement
Reduced p-eIF2α-mediated translational control increases the susceptibility to nicotine-induced LTP.

(a-b) Left, Representative traces of AMPAR and NMDAR EPSCs recorded from VTA DA neurons 24 hr after i.p. injection of saline or the indicated dose of nicotine. A relatively low dose of nicotine (0.4 mg/kg) induced LTP, shown by an increase in AMPAR/NMDAR ratio in VTA DA neurons (a, Right, P<0.01, n=6,6 saline/0.4 mg/kg nicotine, t10=4.026) from adolescent mice (5 weeks old), but not in those from adult mice (3–5 months old, b, Right, P=0.802, n=6/7/6 saline/0.4 mg/kg nicotine/1.0 mg/kg nicotine, F2,16=9.029). A higher dose of nicotine (1.0 mg/kg) was required to increase the AMPAR/NMDAR ratio in VTA DA neurons from adult mice (b, Right, P<0.05 vs. saline or 1.0 mg/kg nicotine, n=6/7/6 saline/0.4 mg/kg nicotine/1.0 mg/kg nicotine, F2,16=9.029). (c-d) A low dose of nicotine (0.4 mg/kg) reduced p-eIF2α in the VTA of adolescents (c, P<0.05, n=9/5 saline/0.4 mg/kg nicotine, t12=2.479), but not adult mice (d, P=0.5710, n=7/11 saline/0.4 mg/kg nicotine, t16=0.5784). (e) A higher dose of nicotine (1 mg/kg) was required to reduce p-eIF2α in VTA of adult mice (P<0.01, n=11/5 saline/1 mg/kg nicotine, t14=3.428). (f) A low dose of nicotine (0.4 mg/kg) failed to induce LTP in VTA DA neurons from adult WT (Eif2s1S/S) mice (Left, P=0.964, n=5 per group, t8=0.05), but elicited significant LTP in adult Eif2s1S/A mice (Right, P=0.003, n=5 per group, t8=6.73). (g) A low dose of nicotine (0.4 mg/kg) induced LTP in ISRIB-injected adult mice compared to vehicle-injected mice (P<0.001, n=7/7 nicotine+vehicle/nicotine+ISRIB, t12=5.222).

https://doi.org/10.7554/eLife.12056.003
Figure 1—figure supplement 1
Adolescent mice are more susceptible than adult mice to nicotine-induced synaptic potentiation.

Adolescent (5 weeks old, n=6–7 per group) or adult mice (3–5 months old, n=6–7 per group) were i.p-injected with saline or nicotine at indicated doses and whole-cell recordings were performed in VTA DA neurons. An increase in the AMPAR/NMDAR ratio (an index of LTP) was induced with the 0.4 mg/kg dose of nicotine (F2,32=4.34, P<0.01 vs. saline) in adolescent mice, whereas 1.0 mg/kg was required for a significant increase in adults (F2,32=4.34, P<0.05 vs. saline or 0.4 mg/kg nicotine).

https://doi.org/10.7554/eLife.12056.004
Figure 2 with 3 supplements
The effect of a single nucleotide polymorphism (SNP) in the promoter of the Eif2s1 gene on reward-dependent striatal activity in human tobacco smokers.

(a-c) Reward-related activity in caudate/putamen is lower in smokers than non-smokers (b, P<0.01, n=33/55, t86=2.678). (b-c) Transverse (b) and sagittal (c) views of significant fMRI BOLD signal in caudate/putamen of non-smokers compared to smokers in response to juice reward. (d) Interaction between smoking and rs10144417 genotype (P<0.05, F1,86=5.836). (e) Partial alignment of Eif2s1 promoter sequences in human and related animals. Note high level of nucleotide conservation: the rs10144417 SNP is indicated in blue and the non-conserved nucleotides in red. (f) Schematic of firefly luciferase reporter constructs, in which a 5-kb Eif2s1 promoter fragment containing either the A or G allele was cloned upstream of the firefly luciferase gene in the p15Amp reporter vector. A renilla luciferase reporter was co-transfected with reporters containing the A or G variant and firefly luciferase (Fluc) activity was normalized to renilla (Rluc) activity. (g) Effects of A and G variants of SNP rs10144417 on the transcriptional activity of the Eif2s1 promoter as assessed by a luciferase reporter assay in HEK-293 cells. The data are from three independent experiments (P<0.001, n=6 per group, t10=5.405). (h) Western blotting showing that overexpression of Eif2s1 (pRc/CMV-Eif2s1) increased eIF2α levels compared to control (vector alone pRc/CMV). (i) Diagram of the 5′ UTR-Ophn1-Fluc reporter, which consists of the 5’UTR of Ophn1 mRNA fused to the coding region of Firefly luciferase (Fluc). A renilla luciferase (Rluc) reporter vector was co-transfected into HEK293T as a transfection control. (j) Overexpression of Eif2s1 reduced expression of 5′ UTR-Ophn1-Fluc (P<0.01, n=6, t10=3.9425).

https://doi.org/10.7554/eLife.12056.005
Figure 2—figure supplement 1
Demographic information of human participants involved in fMRI studies.

(a) Table showing the number of participants by gender, age, and smoking status carrying the A or the G variant in the Eif2s1 gene. (b) Table showing the number of participants by their self-reported ethnicities The participants have no history of any other drug dependance.

https://doi.org/10.7554/eLife.12056.006
Figure 2—figure supplement 2
fMRI recording paradigm and reward-stimulus pairing in human smokers.

(a) The fMRI recording session consisted of four 5–7 min blocks of light-juice pairings. A self-paced break (“inter-run interval”) was included between runs to allow participants to ask any questions and to allow the investigators to provide feedback on participant motion within the scanner. (b) A total of fifty-five light-juice (1 mL) pairings were presented. The delay between light and juice was 7 s.

https://doi.org/10.7554/eLife.12056.007
Figure 2—figure supplement 3
ATF4-Luciferase construct design and activity with Eif2s1.

(a) Diagram of the 5 UTR-ATF4 Fluc reporter, which consists of the 5’UTR of ATF4 mRNA fused to the coding region of Firefly luciferase (Fluc). A renilla luciferase (Rluc) reporter vector was co-transfected into HEK293T as a transfection control. (b) Overexpression of Eif2s1 reduced expression of 5 UTR-ATF4-Fluc (P<0.0001, n=4 per group, t6=11.33).

https://doi.org/10.7554/eLife.12056.008

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