Layer specific and general requirements for ERK/MAPK signaling in the developing neocortex
- The University of North Carolina School of Medicine, United States
- Allen Institute for Brain Science, United States
- Arizona State University, United States
- University of North Carolina at Chapel Hill, United States
Figures
Figure 1 with 1 supplement
Loss of ERK/MAPK signaling leads to a reduction in the number of CTIP+ layer 5 neurons and reduced neuronal somal size.
(A–B). Immunostaining of P14 control (A) and Map2k1/2;Neurod6-Cre (B) sagittal forebrain sections for all neurons, callosal projection neurons, and subcortical projection neurons with NEUN, SATB2, …
Figure 1—figure supplement 1
Developmental changes in ERK/MAPK activity and mouse models for loss of ERK/MAPK signaling in cortical excitatory neurons.
(A) Whole cortical lysates show significant changes in the expression and phosphorylation of ERK/MAPK components, MAP2K1/2 and MAPK1/3(ERK1/2), during the first three weeks of postnatal development …
Figure 2 with 1 supplement
Corticospinal tract defects in Map2k1/2;Neurod6-Cre mice.
(A–D) To further evaluate the loss of layer 5 projection neurons, we examined the expression of a well-established corticospinal tract marker, PKCγ. Compared to control hindbrains (A) and spinal …
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Figure 2—source data 1
Reduced expression of layer 5 neuron markers following loss of Map2k1/2.
(A) Gene expression profiling of RNA extracts from the cortex of control and Map2k1/2;Neurod6-Cre mice collected at P9 (n=2) and P14 (n=3) revealed significantly diminished expression (fold change>1.5 and p<0.05) of many genes that are known to be expressed in layer 5 neurons (red filled boxes).
- https://doi.org/10.7554/eLife.11123.006
Figure 2—figure supplement 1
Reduced number of corticospinal neurons following loss of Map2k1/2.
(A–B) Similar to results with Neurod6-Cre mice, deletion of Map2k1/2 with Emx1-Cre also led to a disruption of CTIP2 labeling in layer 5 sensorimotor cortices in Map2k1/2;Emx1-Cre mice (B) when …
Figure 3 with 1 supplement
Layer 5 neuron corticospinal axon outgrowth requires ERK/MAPK signaling in vivo.
(A–C) Expression of a well-known master transcription factor for layer 5 neurons, CTIP2, was intact in cortical layer 5 as shown in representative confocal images of newborn control (A) and Map2k1/2;…
Figure 3—figure supplement 1
The rostrocaudal elongation of layer 5 axons in the spinal cord requires ERK/MAPK, but not IGF1R, signaling.
(A–B) In vivo DiI injections into the sensorimotor cortex were performed in P0.5 control and Map2k1/2;Neurod6-Cre neonates to label subcortical projection neuron afferents (A). Mice were collected …
Figure 4
Initiation of layer 5 neuron death by P3 in Map2k1/2;Neurod6-Cre mutants.
(A–B) Representative confocal images of immunolabeling for cleaved activated caspase-3, a well-known marker of neuronal apoptosis in P3 control (A) and Map2k1/2;Neurod6-Cre (B) sensorimotor …
Figure 5 with 1 supplement
Gain of function ERK/MAPK signaling in ca-Map2k1;Neurod6-Cre mice decreases corticospinal extension into the spinal cord.
(A–C) Representative confocal images of sensory cortices show that the expression and distribution of the callosal projection neuron marker, SATB2, and subcerebral projection neuron marker, CTIP2, …
Figure 5—figure supplement 1
Mouse model for excitatory neuron specific gain-of-ERK/MAPK signaling in the cortex.
(A–B) Representative confocal images of forebrain sections from controls (A) and ca-Map2k1;Neurod6-Cre mutants (B) demonstrate that the expression of MAP2K1 is substantially higher in excitatory …
Figure 6 with 1 supplement
Hyperactivation of ERK/MAPK enhances axonal branching in the hindbrain and spinal cord.
(A–J) AAV5-FLEX-tdTomato injections into control (Neurod6-Cre) and ca-Map2k1;Neurod6-Cre motor cortices at P1 (inset in A–B) results in labeling of subcerebral axon projections in P30 hindbrains (A–F…
Figure 6—figure supplement 1
ca-Map2k1;Emx1-Cre mice exhibit alterations in the pattern of corticospinal outgrowth in the spinal cord similar to ca-Map2k1;Neurod6-Cre mutants.
(A–D) The entire pattern of corticospinal branching can be visualized in Emx1-Cre;Ai3 mice. P30 ca-Map2k1;Emx1-Cre;Ai3 mice showed a significant reduction in the area of corticospinal labeling in …
Figure 7 with 1 supplement
The differentiation and morphology of callosal projecting neurons in layer 2/3 does not require ERK/MAPK signaling during development.
(A–E) Analysis of intracortical neuron markers, CUX1 (A–B) and SATB2 (C–D), from confocal images of P14 control (A, C) and Map2k1/2;Neurod6-Cre (B, D) sensory cortices did not reveal significant …
Figure 7—figure supplement 1
ERK/MAPK signaling is dispensable for the differentiation and axonal morphology of callosal projection neurons in layer 2/3.
(A–B) Co-in utero electroporation (IUEP) of pNeurod1-Cre and ploxp-STOP-loxp-EGFP plasmids into E14.5 control (Map2k1loxp/wt;Map2k2-/-) and mutant (Map2k1loxp/loxp;Map2k2-/-) embryonic ventricles …
Figure 8 with 1 supplement
ERK/MAPK signaling promotes ARC expression and reduces neuron excitability in layer 2/3 and 5 pyramidal neurons during development.
(A) Microarray profiling of whole cortical lysates detected a significant decrease in the expression of activity-dependent genes in P14 Map2k1/2;Neurod6-Cre mice compared to controls (n=3). (B) …
Figure 8—figure supplement 1
Loss of ERK/MAPK signaling leads to imbalanced excitatory and inhibitory synaptic drive in layer 2/3 neurons.
(A) Intrinsic membrane properties and action potential properties of layer 5 (n=16 control, 14 mutant neurons, mean ± SEM) and layer 2/3 (n=14 control, 14 mutant neurons, mean ± SEM) neurons …
