Neuronal activity disrupts myelinated axon integrity in the absence of NKCC1b

Through a genetic screen in zebrafish, we identified a mutant with disruption to myelin in both the CNS and PNS caused by a mutation in a previously uncharacterized gene, slc12a2b, predicted to encode a Na+, K+, and Cl− (NKCC) cotransporter, NKCC1b. slc12a2b/NKCC1b mutants exhibited a severe and progressive pathology in the PNS, characterized by dysmyelination and swelling of the periaxonal space at the axon–myelin interface. Cell-type–specific loss of slc12a2b/NKCC1b in either neurons or myelinating Schwann cells recapitulated these pathologies. Given that NKCC1 is critical for ion homeostasis, we asked whether the disruption to myelinated axons in slc12a2b/NKCC1b mutants is affected by neuronal activity. Strikingly, we found that blocking neuronal activity completely prevented and could even rescue the pathology in slc12a2b/NKCC1b mutants. Together, our data indicate that NKCC1b is required to maintain neuronal activity–related solute homeostasis at the axon–myelin interface, and the integrity of myelinated axons.

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Disruption to NKCC1 impairs the response of myelinating Schwann cells to neuronal activity and leads to severe peripheral nerve pathology

10.1101/757831 ◽

2019 ◽

Cited By ~ 2

Author(s):

Linde Kegel ◽

Katy LH Marshall-Phelps ◽

Marion Baraban ◽

Rafael G Almeida ◽

Maria Rubio-Brotons ◽

...

Keyword(s):

Peripheral Nerve ◽

Schwann Cells ◽

Neuronal Activity ◽

Peripheral Nerves ◽

Ion Homeostasis ◽

Myelinated Axon ◽

Loss Of Function ◽

Cell Type Specific ◽

Solute Carrier

AbstractMyelinating Schwann cells of the peripheral nervous system (PNS) express numerous ion channels and transporters, and have the capacity to respond to neuronal activity. However, it remains unknown how the response of Schwann cells to neuronal activity affects peripheral nerve formation, health or function in vivo. Through a genetic screen in zebrafish, we identified a mutant, ue58, with severe disruption to the morphology of myelin along peripheral nerves and associated nerve oedema. Molecular analyses indicated that this phenotype was caused by the loss of function of a previously uncharacterized gene, slc12a2b, which encodes a zebrafish paralog of the solute carrier NKCC1. NKCC1 is a co-transporter of Na+, K+, and Cl− ions and water, typically from the extracellular space into cells. Upon impairing slc12a2b function, constitutively, or specifically in neurons or myelinating Schwann cells, we observed disruption to myelin and nerve oedema. Strikingly, we found that treatment of slc12a2b mutants with TTX completely prevented the emergence of these pathologies. Furthermore, TTX treatment rescued pathology in animals with cell-type specific loss of slc12a2b from myelinating Schwann cells. Together our data indicate that NKCC1 regulates ion homeostasis following neuronal activity and that this is required to maintain myelinated axon and peripheral nerve integrity.

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Molecular and cellular adaptations in hippocampal parvalbumin neurons mediate behavioral responses to chronic social stress

10.1101/2021.09.14.459024 ◽

2021 ◽

Author(s):

Dionnet L Bhatti ◽

Lucian Medrihan ◽

Michelle X Chen ◽

Junghee Jin ◽

Kathryn McCabe ◽

...

Keyword(s):

Neuronal Activity ◽

Affinity Purification ◽

Behavioral Outcomes ◽

Behavioral Responses ◽

Specific Gene ◽

Mrna Levels ◽

Cell Type ◽

Stress Resilience ◽

Cell Type Specific ◽

Stress Susceptibility

BACKGROUND: Behavioral responses to stress are, in part, mediated by the hippocampus and Parvalbumin (PV)-expressing neurons. However, whether chronic stress induces molecular and cellular adaptations in hippocampal PV neurons contribute to stress-induced behavioral outcomes remains elusive. METHOD: Using chronic social defeat stress (CSDS), we investigated the role of neuronal activity and gene expression in hippocampal PV neurons in mediating stress-resilience and -susceptibility. We first used in vivo high-density silicon probe recordings and chemogenetics to test whether the activity of PV neurons in ventral dentate gyrus (PVvDG) is associated with particular behavioral outcomes. To find critical molecular pathways associated with stress-resilience and -susceptibility, we used PV-neuron-selective translating ribosome affinity purification and RNAseq. We used immunoblotting, RNAscope, and region- or cell type-specific gene deletion to determine whether Ahnak, a molecule regulating depression-like behavior, was necessary for behavioral divergence after CSDS. RESULTS: We find CSDS modulates neuronal activity in vDG. Notably, stress-susceptibility is associated with an increase of PVvDG firing, which we find is necessary and sufficient for susceptibility. Additionally, genes involved in mitochondrial function, protein synthesis and synaptogenesis are differentially expressed in hippocampal PV neurons of stress-resilient and -susceptible mice. Interestingly, protein and mRNA levels of Ahnak, an endogenous regulator of L-type calcium channels are associated with susceptibility after CSDS. vDG- and PV cell type-specific deletions reveal that Ahnak is required for stress-susceptibility to CSDS. CONCLUSIONS: These findings indicate that CSDS-induced molecular and cellular adaptations in hippocampal PV neurons mediate behavioral consequences, proposing a mechanism underlying individual differences in stress vulnerability.

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Misregulation of poly(ADP-ribose) polymerase-1 activity and cell type-specific loss of poly(ADP-ribose) synthesis in the cerebellum of aged rats

Journal of Neurochemistry ◽

10.1111/j.1471-4159.2005.03082.x ◽

2005 ◽

Vol 93 (4) ◽

pp. 1000-1009 ◽

Cited By ~ 4

Author(s):

M. Malanga ◽

M. Romano ◽

A. Ferone ◽

A. Petrella ◽

G. Monti ◽

...

Keyword(s):

Aged Rats ◽

Cell Type ◽

Specific Loss ◽

Cell Type Specific

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Secreted reporter assay enables quantitative and longitudinal monitoring of neuronal activity

10.1101/2021.01.22.427811 ◽

2021 ◽

Author(s):

Ana C. Santos ◽

Sungjin Park

Keyword(s):

Neuronal Activity ◽

Specific Activity ◽

Repeated Measurements ◽

Reporter Assay ◽

Cell Type ◽

Conditional Expression ◽

Specific Manner ◽

A Cell ◽

Cell Type Specific ◽

And Function

AbstractThe ability to measure changes in neuronal activity in a quantifiable and precise manner is of fundamental importance to understand neuron development and function. Repeated monitoring of neuronal activity of the same population of neurons over several days is challenging and, typically, low-throughput. Here, we describe a new biochemical reporter assay that allows for repeated measurements of neuronal activity in a cell type-specific manner. We coupled activity-dependent elements from the Arc/Arg3.1 gene with a secreted reporter, Gaussia luciferase, to quantify neuronal activity without sacrificing the neurons. The reporter predominantly senses calcium and NMDA receptor-dependent activity. By repeatedly measuring the accumulation of the reporter in cell media, we can profile the developmental dynamics of neuronal activity in cultured neurons from male and female mice. The assay also allows for longitudinal analysis of pharmacological treatments, thus distinguishing acute from delayed responses. Moreover, conditional expression of the reporter allows for monitoring cell type-specific changes. This simple, quantitative, cost-effective, automatable, and cell type-specific activity reporter is a valuable tool to study the development of neuronal activity in normal and disease-model conditions, and to identify small molecules or protein factors that selectively modulate the activity of a specific population of neurons.SignificanceNeurological and neurodevelopmental disorders are prevalent worldwide. Despite significant advances in our understanding of synapse formation and function, developing effective therapeutics remains challenging, in part due to the lack of simple and robust high-throughput screening assays of neuronal activity. Here, we describe a simple biochemical assay that allows for repeated measurements of neuronal activity in a cell type-specific manner. Thus filling the need for assays amenable to longitudinal studies, such as those related to neural development. Other advantages include its simple and quantitative nature, logitudinal profiling, cell type-specificity, and being multiplexed with other invasive techniques.

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