BDNF/TrkB signaling endosomes in axons coordinate CREB/mTOR activation and protein synthesis in the cell body to induce dendritic growth in cortical neurons
- Department of Physiology, Faculty of Biological Sciences and Center for Aging and Regeneration), Pontificia Universidad Católica de Chile. Av. Libertador Bernardo O´Higgins, Chile
- NeuroSignaling Lab (NESLab), Center for Aging and Regeneration (CARE-UC), Institute of Biomedical Sciences (ICB), Faculty of Medicine, and Faculty of Life Sciences, Universidad Andrés Bello, Chile
- Department of Neurosciences, University of California, San Diego, United States
- Department of Physiology and Pharmacology, Sackler Faculty of Medicine; Sagol School of Neuroscience, Tel Aviv University, Israel
Figures
Figure 1 with 1 supplement
Addition of BDNF to axons promotes dendritic branching in a TrkB-dependent manner.
(A) Representative images of compartmentalized microfluidic chambers (400 µm long and 15 µm wide microgrooves) after addition of BDNF/Ctb-555. Ctb-555 (upper left panel), EGFP (upper right panel), …
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Figure 1—source data 1
Addition of BDNF to axons promotes dendritic branching in a TrkB-dependent manner.
- https://cdn.elifesciences.org/articles/77455/elife-77455-fig1-data1-v1.xlsx
Figure 1—figure supplement 1
Experimental design used to study retrograde BDNF signaling in compartmentalized cortical neurons.
(A) Representative images of compartmentalized neurons whose axons were incubated with Ctb-555 for 48 hr. Neurons were immunostained for MAP2 (green). The arrows indicate neurons that projected …
Figure 2
Axonal BDNF increases dendritic arborization in a p75-independent manner.
(A) Representative images of the CB (red indicates Ctb-555) of compartmentalized p75WT, p75HET, or p75KO mouse cortical neurons whose axons were treated with BDNF (50 ng/mL). Quantification of …
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Figure 2—source data 1
Axonal BDNF increases dendritic arborization in a p75-independent manner.
- https://cdn.elifesciences.org/articles/77455/elife-77455-fig2-data1-v1.xlsx
Figure 3 with 3 supplements
CREB activity is required for long-distance axonal BDNF-induced dendritic arborization.
(A) Lower panel, schematic representation of the protocol used to evaluate CREB phosphorylation induced by axonal BDNF and the requirement of CREB for dendritic arborization induced by BDNF using …
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Figure 3—source data 1
CREB activity is required for long-distance axonal BDNF-induced dendritic arborization.
- https://cdn.elifesciences.org/articles/77455/elife-77455-fig3-data1-v1.xlsx
Figure 3—figure supplement 1
Evaluation of CREB activation in different p75 strains.
DIV seven cortical neurons from p75WT, p75HET, or p75KO mice were treated with BDNF (50 ng/mL) for 30 min, washed and fixed for immunostaining for pCREB (S133), as indicated in the Materials and …
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Figure 3—figure supplement 1—source data 1
Evaluation of CREB activation in different p75 strains.
Graph B’s raw data.
- https://cdn.elifesciences.org/articles/77455/elife-77455-fig3-figsupp1-data1-v1.xlsx
Figure 3—figure supplement 2
Evaluation of neuronal survival after KG501 treatment.
(A) To control cell death induced by KG501, we performed the experiments as described in Figure 3C–F and visualization of DNA fragmentation in fixed cells by TUNEL staining (green) was performed. …
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Figure 3—figure supplement 2—source data 1
Evaluation of neuronal survival after KG501 treatment.
Graph B´s raw data.
- https://cdn.elifesciences.org/articles/77455/elife-77455-fig3-figsupp2-data1-v1.xlsx
Figure 3—figure supplement 3
Expression of a dominant-negative mutant of CREB (CREB-DN-EGFP) in the pyramidal neurons of the sensory-motor cortex of mouse brain induced dendritic retraction and shrinkage of neuronal body size.
(A) Representative image of a mouse brain injected unilaterally with AAV1 into layer II/III of the motor cortex. Scale bar = 500 µm. (B) Representative image of neurons expressing EGFP/mCherry or …
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Figure 3—figure supplement 3—source data 1
Expression of a dominant-negative mutant of CREB (CREB-DN-EGFP) in the pyramidal neurons of the sensory-motor cortex of mouse brain induced dendritic retraction and shrinkage of neuronal body size.
Graph D-G´s raw data.
- https://cdn.elifesciences.org/articles/77455/elife-77455-fig3-figsupp3-data1-v1.xlsx
Figure 4
Dynein activity is required for phosphorylation of CREB and dendritic arborization induced by BDNF.
(A) Schematic representation of the protocol used to evaluate the retrograde transport of BDNF. Biotinylated BDNF conjugated to streptavidin QD-655 (2 nM) was added to AC for 4 hr in the presence or …
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Figure 4—source data 1
Dynein activity is required for phosphorylation of CREB and dendritic arborization induced by BDNF.
- https://cdn.elifesciences.org/articles/77455/elife-77455-fig4-data1-v1.xlsx
Figure 5 with 1 supplement
Somatodendritic activity of axonal TrkB is required for long-distance BDNF signaling.
(A) Schematic representation of the protocol used to label axonal TrkB. DIV five compartmentalized cortical neurons were transfected with Flag-TrkB for 48 hr. At DIV seven, anti-Flag antibody was …
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Figure 5—source data 1
Somatodendritic activity of axonal TrkB is required for long-distance BDNF signaling.
- https://cdn.elifesciences.org/articles/77455/elife-77455-fig5-data1-v1.xlsx
Figure 5—figure supplement 1
1NM-PP1 can reduce TrkB activation in TrkBF616A mouse cortical neurons after BDNF treatment.
(A) Diagrams of the experimental designs used to stimulate neurons in noncompartmentalized cultures. The medium of DIV 7 cortical neurons was removed for 1 hr, and the neurons were treated with or …
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Figure 5—figure supplement 1—source data 1
1NM-PP1 can reduce TrkB activation in TrkBF616A mouse cortical neurons after BDNF treatment.
Original Western blots supporting Figure 5—figure supplement 1. This source data contains the original Western blots that supports the Figure 5—figure supplement 1. The images are separated in folders each one corresponding to independent experiments (N1, N2, N3). In the original pictures, the order of lines is the same than in Figure 5—figure supplement 1B and the name of the file indicates the antibody used to develop the nitrocellulose membrane.
- https://cdn.elifesciences.org/articles/77455/elife-77455-fig5-figsupp1-data1-v1.zip
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Figure 5—figure supplement 1—source data 2
1NM-PP1 can reduce TrkB activation in TrkBF616A mouse cortical neurons after BDNF treatment.
Graph C, D, F-H´s raw data.
- https://cdn.elifesciences.org/articles/77455/elife-77455-fig5-figsupp1-data2-v1.xlsx
Figure 6
Axonal BDNF colocalizes with active TrkB in signaling endosomes within cell bodies and dendrites of compartmentalized cortical neurons.
(A) Left panel, schematic representation of the protocol used to stimulate neurons. Right panel, DIV 4 neurons were transduced with AAV1 expressing mCherry. After 4 days, Ctb-647 (Ctb, red) and …
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Figure 6—source data 1
Axonal BDNF colocalizes with active TrkB in signaling endosomes within cell bodies and dendrites of compartmentalized cortical neurons.
- https://cdn.elifesciences.org/articles/77455/elife-77455-fig6-data1-v1.xlsx
Figure 7 with 2 supplements
Activation of PI3K activity in the cell body but not the axons is required for dendritic arborization induced by axonal BDNF.
(A) Schematic representation of the protocol used to stimulate compartmentalized cortical neurons. DIV six cortical neurons were transfected with EGFP, and then TrkB-Fc (100 ng/mL) was added to the …
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Figure 7—source data 1
Activation of PI3K activity in the cell body but not the axons is required for dendritic arborization induced by axonal BDNF.
- https://cdn.elifesciences.org/articles/77455/elife-77455-fig7-data1-v1.xlsx
Figure 7—figure supplement 1
PI3K activation is required for BDNF signaling in cortical neurons.
(A) Representative images of rat cortical neurons in non-compartmentalized cultures treated with vehicle, LY294002 (10 μM), BDNF (50 ng/mL) or BDNF after preincubation with LY294002. Scale bar = 20 …
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Figure 7—figure supplement 1—source data 1
PI3K activation is required for BDNF signaling in cortical neurons.
Graph B´s raw data.
- https://cdn.elifesciences.org/articles/77455/elife-77455-fig7-figsupp1-data1-v1.xlsx
Figure 7—figure supplement 2
PI3K and mTOR activity is required for activation of downstream TrkB signaling pathways.
Western blot analysis of DIV 7 non-compartentalized neurons treated with BDNF (50 ng/mL) in the presence or absence of LY294002 (10 μM) or Torin 1 (0.25 μM) for 1 hr. pTrkB (Y515), TrkB, pAkt …
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Figure 7—figure supplement 2—source data 1
This source data contains the original western blots that supports the Figure 7—figure supplement 2.
In the original pictures, the order of lines is the same than in Figure 7—figure supplement 2 and the name of the file indicates the antibody used to develop the nitrocellulose membrane.
- https://cdn.elifesciences.org/articles/77455/elife-77455-fig7-figsupp2-data1-v1.zip
Figure 8 with 1 supplement
Axonal BDNF promotes mTOR activation in the cell bodies of compartmentalized cortical neurons in a PI3K-dependent manner.
(A) Representative images of p4E-BP1 immunostaining (green) and Ctb-555 (red). DIV six compartmentalized cortical neurons were incubated with Ctb-555 overnight. At DIV 7, BDNF (50 ng/mL) was added …
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Figure 8—source data 1
Axonal BDNF promotes mTOR activation in the cell bodies of compartmentalized cortical neurons in a PI3K-dependent manner.
- https://cdn.elifesciences.org/articles/77455/elife-77455-fig8-data1-v1.xlsx
Figure 8—figure supplement 1
BDNF added to axons increases pS6r in cell bodies.
(A) Representative images of β-III-tubulin (green) and pS6r (red) in cortical neurons whose axons were stimulated with BDNF (50 ng/mL) for 180 min. Scale bar = 50 μm. (B) Quantification of pS6r …
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Figure 8—figure supplement 1—source data 1
BDNF added to axons increases pS6r in cell bodies.
Graph B´s raw data.
- https://cdn.elifesciences.org/articles/77455/elife-77455-fig8-figsupp1-data1-v1.xlsx
Figure 9 with 1 supplement
Axonal BDNF promotes somatodendritic protein synthesis in an mTOR- and CREB-dependent manner.
(A) Schematic representation of the protocol used to evaluate protein synthesis. DIV 6–7 cortical neurons were incubated in methionine-free medium for 1 hr, and KG501 (10 µm) or Torin 1 (0.25 µm) …
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Figure 9—source data 1
Axonal BDNF promotes somatodendritic protein synthesis in an mTOR- and CREB-dependent manner.
- https://cdn.elifesciences.org/articles/77455/elife-77455-fig9-data1-v1.xlsx
Figure 9—figure supplement 1
Visualization of protein translation inusing AHA.
Representative image of AHA staining in neurons treated with BDNF for 5 hr in the presence or absence of cycloheximide. Right panel, color code for intensity. Scale bar = 20 µm.
Additional files
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Transparent reporting form
- https://cdn.elifesciences.org/articles/77455/elife-77455-transrepform1-v1.pdf
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Supplementary file 1
List of materials and reagents.
- https://cdn.elifesciences.org/articles/77455/elife-77455-supp1-v1.xlsx
