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Mice lacking integrin β3 expression exhibit altered response to chronic stress.

Varney S, Polston KF, Jessen T, Carneiro AM - Neurobiol Stress (2015)

Bottom Line: We found that genetic abrogation of integrin β3 expression elicits an exaggerated vulnerability to chronic unpredictable stress in the open field test.Semi-quantitative Western blot studies revealed that the synaptic expression, but not total tissue expression, of multiple signaling proteins is correlated with integrin αv levels in the midbrain.Moreover, loss of integrin β3 expression modifies this correlation network.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Pharmacology, Vanderbilt University Medical Center, Nashville, TN 37232-6600, USA.

ABSTRACT

Recent studies indicate multiple roles for integrin αvβ3 in adult neurons, including response to pharmacological agents such as cocaine and selective serotonin reuptake inhibitors. In this study, we examined the role of the integrin β3 gene (Itgb3) in the response to environmental stimuli by subjecting Itgb3 (+/+) and Itgb3 (-/-) mice to unpredictable chronic mild stressors. We found that genetic abrogation of integrin β3 expression elicits an exaggerated vulnerability to chronic unpredictable stress in the open field test. In this test, chronic stress elicited significant decreases in stereotypic behavior and horizontal locomotor activity, including increases in anxiety behaviors. Mild chronic stress led to reductions in dopamine turnover in midbrains of Itgb3 (+/+), but not Itgb3 (-/-) mice, suggesting a disruption of stress-dependent regulation of DA homeostasis. Chronic stress elicited altered synaptic expression of syntaxin and synaptophysin in midbrains of Itgb3 (-/-) mice, when compared to Itgb3 (+/+). Semi-quantitative Western blot studies revealed that the synaptic expression, but not total tissue expression, of multiple signaling proteins is correlated with integrin αv levels in the midbrain. Moreover, loss of integrin β3 expression modifies this correlation network. Together, these findings demonstrate that Itgb3 (-/-) mice display a pattern of changes indicating disrupted regulation of midbrain synaptic systems involved in conferring resilience to mild stressors.

No MeSH data available.


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Western blot analysis of synaptic expression of several signaling, structural, and glutamate receptor subunits in the midbrain. Expression levels for each protein are normalized to both Na+/K+ ATPase and Itgb3+/+Control. a, Representative Western blots from whole tissue (left column) and synaptosome fractions (right column). b, Synaptic PSD-95 expression is not modified by chronic stress in Itgb3-/- mice. Itgb3+/+Control N = 9, Itgb3+/+UCMS N = 6, Itgb3-/-Control N = 9, Itgb3-/-cs N = 9. c, Synaptic syntaxin expression. Itgb3+/+Control N = 7, Itgb3UCMS N = 6, Itgb3-/-Control N = 8, Itgb3-/-UCMS N = 8. c, Synaptic synaptophysin expression. Itgb3+/+Control N = 4, Itgb3+/+UCMS N = 3, Itgb3-/-Control N = 4, Itgb3-/-UCMS N = 4). *P < 0.05 for control vs. UCMS post-tests, and #P < 0.05 for genotype comparisons within treatment group. All post-tests P values are Bonferonni corrected.
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Figure 2: Western blot analysis of synaptic expression of several signaling, structural, and glutamate receptor subunits in the midbrain. Expression levels for each protein are normalized to both Na+/K+ ATPase and Itgb3+/+Control. a, Representative Western blots from whole tissue (left column) and synaptosome fractions (right column). b, Synaptic PSD-95 expression is not modified by chronic stress in Itgb3-/- mice. Itgb3+/+Control N = 9, Itgb3+/+UCMS N = 6, Itgb3-/-Control N = 9, Itgb3-/-cs N = 9. c, Synaptic syntaxin expression. Itgb3+/+Control N = 7, Itgb3UCMS N = 6, Itgb3-/-Control N = 8, Itgb3-/-UCMS N = 8. c, Synaptic synaptophysin expression. Itgb3+/+Control N = 4, Itgb3+/+UCMS N = 3, Itgb3-/-Control N = 4, Itgb3-/-UCMS N = 4). *P < 0.05 for control vs. UCMS post-tests, and #P < 0.05 for genotype comparisons within treatment group. All post-tests P values are Bonferonni corrected.

Mentions: We used Western blotting of whole-tissue and synaptoneurosomal preparations from midbrains to identify potential molecular determinants of stress-induced phenotypes influenced by integrin αvβ3 (Fig. 2a). We focused on two major protein groups: proteins involved in canonical integrin signaling (talin, FAK, Src, PP2A, and ERK) and synaptic proteins involved in synapse formation and plasticity (synaptophysin, syntaxin, PSD-95, GluR2, and the NR1 subunit of the NMDA receptor). No significant changes in total tissue protein levels were observed. We then isolated midbrain synaptoneurosomes to identify changes in trafficking and/or synaptic translation events. Synaptic expression of integrin αv, FAK, Src, ERK, PP2A, GluR2, and NMDAR were unaltered by chronic stress or Itgb3 genotype. We observed no changes in post-synaptic PSD-95 levels (Fig. 2b), but observed significant gene × stress interactions in the synaptic levels of syntaxin (Fig. 2c. Interaction: F(1,25) = 10.43; P = 0.003. Itgb3-/-Control vs. Itgb3-/-UCMS, P = 0.022. Itgb3+/+UCMS vs. Itgb3-/-UCMS, P = 0.029) and synaptophysin (Fig. 2d. Interaction: F(1,11) = 15.47; P = 0.002. Itgb3+/+UCMS vs. Itgb3-/-UCMS, P = 0.009). Therefore, loss of Itgb3 expression also confers significant reductions in presynaptic protein expression in the context of chronic unpredictable stress.


Mice lacking integrin β3 expression exhibit altered response to chronic stress.

Varney S, Polston KF, Jessen T, Carneiro AM - Neurobiol Stress (2015)

Western blot analysis of synaptic expression of several signaling, structural, and glutamate receptor subunits in the midbrain. Expression levels for each protein are normalized to both Na+/K+ ATPase and Itgb3+/+Control. a, Representative Western blots from whole tissue (left column) and synaptosome fractions (right column). b, Synaptic PSD-95 expression is not modified by chronic stress in Itgb3-/- mice. Itgb3+/+Control N = 9, Itgb3+/+UCMS N = 6, Itgb3-/-Control N = 9, Itgb3-/-cs N = 9. c, Synaptic syntaxin expression. Itgb3+/+Control N = 7, Itgb3UCMS N = 6, Itgb3-/-Control N = 8, Itgb3-/-UCMS N = 8. c, Synaptic synaptophysin expression. Itgb3+/+Control N = 4, Itgb3+/+UCMS N = 3, Itgb3-/-Control N = 4, Itgb3-/-UCMS N = 4). *P < 0.05 for control vs. UCMS post-tests, and #P < 0.05 for genotype comparisons within treatment group. All post-tests P values are Bonferonni corrected.
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Figure 2: Western blot analysis of synaptic expression of several signaling, structural, and glutamate receptor subunits in the midbrain. Expression levels for each protein are normalized to both Na+/K+ ATPase and Itgb3+/+Control. a, Representative Western blots from whole tissue (left column) and synaptosome fractions (right column). b, Synaptic PSD-95 expression is not modified by chronic stress in Itgb3-/- mice. Itgb3+/+Control N = 9, Itgb3+/+UCMS N = 6, Itgb3-/-Control N = 9, Itgb3-/-cs N = 9. c, Synaptic syntaxin expression. Itgb3+/+Control N = 7, Itgb3UCMS N = 6, Itgb3-/-Control N = 8, Itgb3-/-UCMS N = 8. c, Synaptic synaptophysin expression. Itgb3+/+Control N = 4, Itgb3+/+UCMS N = 3, Itgb3-/-Control N = 4, Itgb3-/-UCMS N = 4). *P < 0.05 for control vs. UCMS post-tests, and #P < 0.05 for genotype comparisons within treatment group. All post-tests P values are Bonferonni corrected.
Mentions: We used Western blotting of whole-tissue and synaptoneurosomal preparations from midbrains to identify potential molecular determinants of stress-induced phenotypes influenced by integrin αvβ3 (Fig. 2a). We focused on two major protein groups: proteins involved in canonical integrin signaling (talin, FAK, Src, PP2A, and ERK) and synaptic proteins involved in synapse formation and plasticity (synaptophysin, syntaxin, PSD-95, GluR2, and the NR1 subunit of the NMDA receptor). No significant changes in total tissue protein levels were observed. We then isolated midbrain synaptoneurosomes to identify changes in trafficking and/or synaptic translation events. Synaptic expression of integrin αv, FAK, Src, ERK, PP2A, GluR2, and NMDAR were unaltered by chronic stress or Itgb3 genotype. We observed no changes in post-synaptic PSD-95 levels (Fig. 2b), but observed significant gene × stress interactions in the synaptic levels of syntaxin (Fig. 2c. Interaction: F(1,25) = 10.43; P = 0.003. Itgb3-/-Control vs. Itgb3-/-UCMS, P = 0.022. Itgb3+/+UCMS vs. Itgb3-/-UCMS, P = 0.029) and synaptophysin (Fig. 2d. Interaction: F(1,11) = 15.47; P = 0.002. Itgb3+/+UCMS vs. Itgb3-/-UCMS, P = 0.009). Therefore, loss of Itgb3 expression also confers significant reductions in presynaptic protein expression in the context of chronic unpredictable stress.

Bottom Line: We found that genetic abrogation of integrin β3 expression elicits an exaggerated vulnerability to chronic unpredictable stress in the open field test.Semi-quantitative Western blot studies revealed that the synaptic expression, but not total tissue expression, of multiple signaling proteins is correlated with integrin αv levels in the midbrain.Moreover, loss of integrin β3 expression modifies this correlation network.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Pharmacology, Vanderbilt University Medical Center, Nashville, TN 37232-6600, USA.

ABSTRACT

Recent studies indicate multiple roles for integrin αvβ3 in adult neurons, including response to pharmacological agents such as cocaine and selective serotonin reuptake inhibitors. In this study, we examined the role of the integrin β3 gene (Itgb3) in the response to environmental stimuli by subjecting Itgb3 (+/+) and Itgb3 (-/-) mice to unpredictable chronic mild stressors. We found that genetic abrogation of integrin β3 expression elicits an exaggerated vulnerability to chronic unpredictable stress in the open field test. In this test, chronic stress elicited significant decreases in stereotypic behavior and horizontal locomotor activity, including increases in anxiety behaviors. Mild chronic stress led to reductions in dopamine turnover in midbrains of Itgb3 (+/+), but not Itgb3 (-/-) mice, suggesting a disruption of stress-dependent regulation of DA homeostasis. Chronic stress elicited altered synaptic expression of syntaxin and synaptophysin in midbrains of Itgb3 (-/-) mice, when compared to Itgb3 (+/+). Semi-quantitative Western blot studies revealed that the synaptic expression, but not total tissue expression, of multiple signaling proteins is correlated with integrin αv levels in the midbrain. Moreover, loss of integrin β3 expression modifies this correlation network. Together, these findings demonstrate that Itgb3 (-/-) mice display a pattern of changes indicating disrupted regulation of midbrain synaptic systems involved in conferring resilience to mild stressors.

No MeSH data available.


Related in: MedlinePlus