1
|
Handwerk CJ, Denzler CJ, Kalinowski AR, Cook HN, Rodriguez HV, Bland KM, Brett CA, Swinehart BD, Vinson EC, Vidal GS. Integrin β3 regulates apical dendritic morphology of pyramidal neurons throughout hippocampal CA3. Hippocampus 2023; 33:936-947. [PMID: 36967540 PMCID: PMC10952146 DOI: 10.1002/hipo.23530] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2022] [Revised: 03/09/2023] [Accepted: 03/13/2023] [Indexed: 03/29/2023]
Abstract
In excitatory hippocampal pyramidal neurons, integrin β3 is critical for synaptic maturation and plasticity in vitro. Itgb3 is a potential autism susceptibility gene that regulates dendritic morphology in the cerebral cortex in a cell-specific manner. However, it is unknown what role Itgb3 could have in regulating hippocampal pyramidal dendritic morphology in vivo, a key feature that is aberrant in many forms of autism and intellectual disability. We found that Itgb3 mRNA is expressed in the stratum pyramidale of CA3. We examined the apical dendritic morphology of CA3 hippocampal pyramidal neurons in conditional Itgb3 knockouts and controls, utilizing the Thy1-GFP-M line. We fully reconstructed the apical dendrite of each neuron and determined each neuron's precise location along the dorsoventral, proximodistal, and radial axes of the stratum pyramidale. We found a very strong effect for Itgb3 expression on CA3 apical dendritic morphology: neurons from conditional Itgb3 knockouts had longer and thinner apical dendrites than controls, particularly in higher branch orders. We also assessed potential relationships between pairs of topographic or morphological variables, finding that most variable pairs were free from any linear relationships to each other. We also found that some neurons from controls, but not conditional Itgb3 knockouts, had a graded pattern of overall diameter along the dorsoventral and proximodistal axes of the stratum pyramidale of CA3. Taken together, Itgb3 is essential for constructing normal dendritic morphology in pyramidal neurons throughout CA3.
Collapse
Affiliation(s)
| | - Collin J. Denzler
- Department of BiologyJames Madison UniversityMSC 7801, HarrisonburgVirginia22807USA
| | - Anna R. Kalinowski
- Department of BiologyJames Madison UniversityMSC 7801, HarrisonburgVirginia22807USA
| | - Hollyn N. Cook
- Department of BiologyJames Madison UniversityMSC 7801, HarrisonburgVirginia22807USA
| | - Hilda V. Rodriguez
- Department of BiologyJames Madison UniversityMSC 7801, HarrisonburgVirginia22807USA
| | - Katherine M. Bland
- Department of BiologyJames Madison UniversityMSC 7801, HarrisonburgVirginia22807USA
| | - Cooper A. Brett
- Department of BiologyJames Madison UniversityMSC 7801, HarrisonburgVirginia22807USA
| | - Brian D. Swinehart
- Department of BiologyJames Madison UniversityMSC 7801, HarrisonburgVirginia22807USA
| | - Elizabeth C. Vinson
- Department of BiologyJames Madison UniversityMSC 7801, HarrisonburgVirginia22807USA
| | - George S. Vidal
- Department of BiologyJames Madison UniversityMSC 7801, HarrisonburgVirginia22807USA
| |
Collapse
|
2
|
Handwerk CJ, Bland KM, Denzler CJ, Kalinowski AR, Brett CA, Swinehart BD, Rodriguez HV, Cook HN, Vinson EC, Florenz ME, Vidal GS. Simultaneous 3D cellular positioning and apical dendritic morphology of transgenic fluorescent mouse CA3 hippocampal pyramidal neurons. J Neurosci Methods 2023; 388:109823. [PMID: 36809825 PMCID: PMC10006342 DOI: 10.1016/j.jneumeth.2023.109823] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2022] [Revised: 01/31/2023] [Accepted: 02/17/2023] [Indexed: 02/21/2023]
Abstract
BACKGROUND Pyramidal neurons throughout hippocampal CA3 are diverse in their dendritic morphology, and CA3 is not homogenous in its structure or function. Nonetheless, few structural studies have captured the precise 3D somatic position and the 3D dendritic morphology of CA3 pyramidal neurons simultaneously. NEW METHOD Here, we present a simple approach to reconstruct the apical dendritic morphology of CA3 pyramidal neurons using the transgenic fluorescent Thy1-GFP-M line. The approach simultaneously tracks the dorsoventral, tangential, and radial positions of reconstructed neurons within the hippocampus. It is especially designed for use with transgenic fluorescent mouse lines, which are commonly used in genetic studies of neuronal morphology and development. RESULTS We demonstrate how topographic and morphological data are captured from transgenic fluorescent mouse CA3 pyramidal neurons. COMPARISON WITH EXISTING METHODS There is no need to select and label CA3 pyramidal neurons with the transgenic fluorescent Thy1-GFP-M line. By taking transverse (not coronal) serial sections, we preserve fine dorsoventral, tangential, and radial somatic positioning of 3D-reconstructed neurons. Because CA2 is well defined by PCP4 immunohistochemistry, we use that technique here to to increase precision in defining tangential position along CA3. CONCLUSIONS We developed a method for simultaneously collecting precise somatic positioning as well as 3D morphological data among transgenic fluorescent mouse hippocampal pyramidal neurons. This fluorescent method should be compatible with many other transgenic fluorescent reporter lines and immunohistochemical methods, facilitating the capture of topographic and morphological data from a wide variety of genetic experiments in mouse hippocampus.
Collapse
Affiliation(s)
- Christopher J Handwerk
- Department of Biology, James Madison University, MSC 7801, Harrisonburg, VA 22807, United States of America
| | - Katherine M Bland
- Department of Biology, James Madison University, MSC 7801, Harrisonburg, VA 22807, United States of America
| | - Collin J Denzler
- Department of Biology, James Madison University, MSC 7801, Harrisonburg, VA 22807, United States of America
| | - Anna R Kalinowski
- Department of Biology, James Madison University, MSC 7801, Harrisonburg, VA 22807, United States of America
| | - Cooper A Brett
- Department of Biology, James Madison University, MSC 7801, Harrisonburg, VA 22807, United States of America
| | - Brian D Swinehart
- Department of Biology, James Madison University, MSC 7801, Harrisonburg, VA 22807, United States of America
| | - Hilda V Rodriguez
- Department of Biology, James Madison University, MSC 7801, Harrisonburg, VA 22807, United States of America
| | - Hollyn N Cook
- Department of Biology, James Madison University, MSC 7801, Harrisonburg, VA 22807, United States of America
| | - Elizabeth C Vinson
- Department of Biology, James Madison University, MSC 7801, Harrisonburg, VA 22807, United States of America
| | - Madison E Florenz
- Department of Biology, James Madison University, MSC 7801, Harrisonburg, VA 22807, United States of America
| | - George S Vidal
- Department of Biology, James Madison University, MSC 7801, Harrisonburg, VA 22807, United States of America.
| |
Collapse
|
3
|
Lopuch AJ, Swinehart BD, Widener EL, Holley ZL, Bland KM, Handwerk CJ, Brett CA, Cook HN, Kalinowski AR, Rodriguez HV, Song MI, Vidal GS. Integrin β3 in forebrain Emx1-expressing cells regulates repetitive self-grooming and sociability in mice. BMC Neurosci 2022; 23:12. [PMID: 35247972 PMCID: PMC8897866 DOI: 10.1186/s12868-022-00691-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2021] [Accepted: 01/28/2022] [Indexed: 12/02/2022] Open
Abstract
Background Autism spectrum disorder (ASD) is characterized by repetitive behaviors, deficits in communication, and overall impaired social interaction. Of all the integrin subunit mutations, mutations in integrin β3 (Itgb3) may be the most closely associated with ASD. Integrin β3 is required for normal structural plasticity of dendrites and synapses specifically in excitatory cortical and hippocampal circuitry. However, the behavioral consequences of Itgb3 function in the forebrain have not been assessed. We tested the hypothesis that behaviors that are typically abnormal in ASD—such as self-grooming and sociability behaviors—are disrupted with conditional Itgb3 loss of function in forebrain circuitry in male and female mice. Methods We generated male and female conditional knockouts (cKO) and conditional heterozygotes (cHET) of Itgb3 in excitatory neurons and glia that were derived from Emx1-expressing forebrain cells during development. We used several different assays to determine whether male and female cKO and cHET mice have repetitive self-grooming behaviors, anxiety-like behaviors, abnormal locomotion, compulsive-like behaviors, or abnormal social behaviors, when compared to male and female wildtype (WT) mice. Results Our findings indicate that only self-grooming and sociability are altered in cKO, but not cHET or WT mice, suggesting that Itgb3 is specifically required in forebrain Emx1-expressing cells for normal repetitive self-grooming and social behaviors. Furthermore, in cKO (but not cHET or WT), we observed an interaction effect for sex and self-grooming environment and an interaction effect for sex and sociability test chamber. Limitations While this study demonstrated a role for forebrain Itgb3 in specific repetitive and social behaviors, it was unable to determine whether forebrain Itgb3 is required for a preference for social novelty, whether cHET are haploinsufficient with respect to repetitive self-grooming and social behaviors, or the nature of the interaction effect for sex and environment/chamber in affected behaviors of cKO. Conclusions Together, these findings strengthen the idea that Itgb3 has a specific role in shaping forebrain circuitry that is relevant to endophenotypes of autism spectrum disorder. Supplementary Information The online version contains supplementary material available at 10.1186/s12868-022-00691-2.
Collapse
|
4
|
Brett CA, Carroll JB, Gabriele ML. Compromised fractalkine signaling delays microglial occupancy of emerging modules in the multisensory midbrain. Glia 2021; 70:697-711. [PMID: 35132709 PMCID: PMC8826074 DOI: 10.1002/glia.24134] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2021] [Revised: 12/13/2021] [Accepted: 12/17/2021] [Indexed: 12/31/2022]
Abstract
Microglial cells (MGCs) are highly dynamic and have been implicated in shaping discrete neural maps in several unimodal systems. MGCs respond to numerous cues in their microenvironment, including the neuronally expressed chemokine, fractalkine (CX3CL1), via interactions with its corresponding fractalkine receptor (CX3CR1). The present study examines microglial and CX3CL1 patterns with regard to the emerging modular-extramodular matrix organization within the lateral cortex of the inferior colliculus (LCIC). The LCIC is a multisensory shell region of the midbrain inferior colliculus where discrete compartments receive modality-specific connections. Somatosensory inputs terminate within modular confines, while auditory inputs target the surrounding matrix. Glutamic acid decarboxylase (GAD) is an established marker of LCIC modules in developing mouse. During early postnatal development, multimodal LCIC afferents segregate into discrete, neurochemically defined compartments. Here, we analyzed neonatal GAD67-GFP (GFP is defined as green fluorescent protein) and CX3CR1-GFP mice to assess: (1) whether MGCs are recruited to distinct LCIC compartments known to be undergoing active circuit assembly, and (2) if such behaviors are fractalkine signaling-dependent. MGCs colonize the nascent LCIC by birth and increase in density until postnatal day 12 (P12). At the peak critical period (P4-P8), MGCs conspicuously border emerging LCIC modules, prior to their subsequent invasion by P12. CX3CL1 expression becomes distinctly modular at P12, in keeping with the notion of fractalkine-mediated recruitment of microglia to modular centers. In CX3CR1GFP/GFP mice with compromised fractalkine signaling, microglial recruitment into modules is delayed. Taken together, these results suggest a potential role for microglia and fractalkine signaling in sculpting multisensory LCIC maps during an early critical period.
Collapse
Affiliation(s)
- Cooper A. Brett
- Department of Biology James Madison University Harrisonburg Virginia USA
| | | | - Mark L. Gabriele
- Department of Biology James Madison University Harrisonburg Virginia USA
| |
Collapse
|
5
|
Stinson JPC, Brett CA, Carroll JB, Gabriele ML. Registry of Compartmental Ephrin-B3 Guidance Patterns With Respect to Emerging Multimodal Midbrain Maps. Front Neuroanat 2021; 15:649478. [PMID: 33815071 PMCID: PMC8010652 DOI: 10.3389/fnana.2021.649478] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2021] [Accepted: 02/23/2021] [Indexed: 11/16/2022] Open
Abstract
Guidance errors and unrefined neural map configurations appear linked to certain neurodevelopmental conditions, including autism spectrum disorders. Deficits in specific multisensory tasks that require midbrain processing are highly predictive of cognitive and behavioral phenotypes associated with such syndromes. The lateral cortex of the inferior colliculus (LCIC) is a shell region of the mesencephalon that integrates converging information from multiple levels and modalities. Mature LCIC sensory maps are discretely-organized, mimicking its compartmental micro-organization. Intermittent modular domains receive patchy somatosensory connections, while inputs of auditory origin terminate in the encompassing extramodular matrix.Eph-ephrin signaling mechanisms instruct comparable topographic arrangements in a variety of other systems. Whether Eph-ephrin interactions also govern the assembly of LCIC multimodal maps remains unaddressed. Previously, we identified EphA4 and ephrin-B2 as key mediators, with overlapping expression patterns that align with emerging LCIC modules. Here, we implicate another member of this guidance family, ephrin-B3, and quantify its transient expression with respect to neurochemically-defined LCIC compartments. Multiple-labeling studies in GAD67-GFP knock-in mice reveal extramodular ephrin-B3 expression, complementary to that of EphA4 and ephrin-B2. This distinctive pattern sharpens over the early postnatal period (birth to P8), prior to ephrin-B3 downregulation once multimodal LCIC inputs are largely segregated (P12). Channel-specific sampling of LCIC ROIs show ephrin-B3 signal periodicities that are out-of-phase with glutamic acid decarboxylase (GAD;modular marker) signal fluctuations, and match calretinin (CR) waveforms (matrix marker). Taken together, the guidance mosaic registry with emerging LCIC compartments and its interfacing afferent streams suggest a prominent role for Eph-ephrins in ordering behaviorally significant multisensory midbrain networks.
Collapse
Affiliation(s)
- Jeremiah P C Stinson
- Department of Biology, James Madison University, Harrisonburg, VA, United States
| | - Cooper A Brett
- Department of Biology, James Madison University, Harrisonburg, VA, United States
| | - Julianne B Carroll
- Department of Biology, James Madison University, Harrisonburg, VA, United States
| | - Mark L Gabriele
- Department of Biology, James Madison University, Harrisonburg, VA, United States
| |
Collapse
|
6
|
Gay SM, Brett CA, Stinson JP, Gabriele ML. Cover Image, Volume 526, Issue 16. J Comp Neurol 2018. [DOI: 10.1002/cne.24567] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Sean M. Gay
- Department of Biology; James Madison University; Harrisonburg Virginia
| | - Cooper A. Brett
- Department of Biology; James Madison University; Harrisonburg Virginia
| | | | - Mark L. Gabriele
- Department of Biology; James Madison University; Harrisonburg Virginia
| |
Collapse
|
7
|
Gay SM, Brett CA, Stinson JPC, Gabriele ML. Alignment of EphA4 and ephrin-B2 expression patterns with developing modularity in the lateral cortex of the inferior colliculus. J Comp Neurol 2018; 526:2706-2721. [PMID: 30156295 DOI: 10.1002/cne.24525] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2018] [Revised: 07/31/2018] [Accepted: 08/21/2018] [Indexed: 01/26/2023]
Abstract
In the multimodal lateral cortex of the inferior colliculus (LCIC), there are two neurochemically and connectionally distinct compartments, termed modular and extramodular zones. Modular fields span LCIC layer 2 and are recipients of somatosensory afferents, while encompassing extramodular domains receive auditory inputs. Recently, in developing mice, we identified several markers (among them glutamic acid decarboxylase, GAD) that consistently label the same modular set, and a reliable extramodular marker, calretinin, (CR). Previous reports from our lab show similar modular-extramodular patterns for certain Eph-ephrin guidance members, although their precise alignment with the developing LCIC neurochemical framework has yet to be addressed. Here we confirm in the nascent LCIC complementary GAD/CR-positive compartments, and characterize the registry of EphA4 and ephrin-B2 expression patterns with respect to its emerging modular-extramodular organization. Immunocytochemical approaches in GAD67-GFP knock-in mice reveal patchy EphA4 and ephrin-B2 domains that precisely align with GAD-positive LCIC modules, and are complementary to CR-defined extramodular zones. Such patterning was detectable neonatally, yielding discrete compartments prior to hearing onset. A dense plexus of EphA4-positive fibers filled modules, surrounding labeled ephrin-B2 and GAD cell populations. The majority of observed GABAergic neurons within modular boundaries were also positive for ephrin-B2. These results suggest an early compartmentalization of the LCIC that is likely instructed in part through Eph-ephrin guidance mechanisms. The overlap of developing LCIC neurochemical and guidance patterns is discussed in the context of its seemingly segregated multimodal input-output streams.
Collapse
Affiliation(s)
- Sean M Gay
- Department of Biology, James Madison University, Harrisonburg, Virginia
| | - Cooper A Brett
- Department of Biology, James Madison University, Harrisonburg, Virginia
| | | | - Mark L Gabriele
- Department of Biology, James Madison University, Harrisonburg, Virginia
| |
Collapse
|