Biology subjects

Moss, S. J.

Publications and source records attributed to Moss, S. J..

9 recordsLinked to original sources

bioRxiv2026

KCC2 Activation Reverses Neurophysiological and Behavioral Deficits in Female Rett Mice

Rett syndrome is an X-linked neurodevelopmental disorder resulting from mutations in the MeCP2 gene, leading to intellectual disability, impaired motor coordination, decreased sociability, and seizures. Central to the underlying pathophysiology are deficits in synaptic inhibition, which are mediated by hyperpolarizing GABAAR currents. These events develop postnatally and are dependent upon increased neuronal Cl- extrusion mediated by SLC12A5 (KCC2). Therefore, we tested whether its activation modifies the disease phenotypes evident in female MeCP2+/- mice, using OV350, a direct activator of KCC2. OV350 rapidly induced a sustained reduction in EEG power, accompanied by a decrease in the severity of epileptic discharges. Increased motor coordination, sociability, and spatial memory were also observed. Deficits in KCC2 phosphorylation were also seen in MeCP2+/- mice, consistent with reductions in its activity that were also ameliorated by OV350. Thus, KCC2 activation may be efficacious in limiting the impact of Rett syndrome and other neurodevelopmental disorders.

neuroscience↗

bioRxiv2025

Activation of KCC2 during development alleviates cognitive, behavioral, and neural excitability in adult CDKL5-deficient mice

Cyclin-dependent kinase-like 5 (CDKL5) deficiency disorder (CDD) is a developmental and epileptic encephalopathy (DEE) characterized by severe drug-resistant epileptic disorders beginning in early childhood, along with cognitive and social impairments in later childhood and adulthood. Existing pharmacological therapies for CDD primarily focus on anti-seizure medications, which often have associated sedative side effects. In addition, there are currently no effective treatments for cognitive or behavioral impairments associated with this disorder. Postnatal development expression of CDKL5 has a similar timeline as the developmental activity of the potassium chloride co-transporter (KCC2), the maturation of which is a prerequisite for the developmental switch to fast synaptic hyperpolarizing inhibition mediated by g-aminobutyric acid type A receptors (GABAAR). This developmental GABA switch is determined by changes in the phosphorylation of multiple residues in KCC2. During this initial postnatal period, dramatic changes occur as major neuronal circuits are formed, laying down the initial pathways important for memory consolidation and behavioral processing. Currently, a knowledge gap exists in understanding KCC2 dysfunction in CDD. In adult Cdkl5 KO mice we found aberrant KCC2 phosphorylation and expression, such that KCC2 phosphorylation profile appeared immature. We examined the developmental changes in KCC2 and observed significant alterations in the phosphorylation of key residues and decreased KCC2 expression from p14 to p21. Because KCC2 loss-of-function has been strongly correlated with excessive neuronal excitation, cognitive and behavioral impairments, we examined seizure susceptibility, spatial memory, and social interaction in adult Cdkl5 KO mice following once daily administration of the KCC2 activator (OV350), or vehicle, to infant Cdkl5 KO mice. We found that adult Cdkl5 KO mice are more susceptible to kainate-induced seizures, show poor sociability and deficits in spatial learning and memory compared to WT mice. Twelve days of OV350 treatment as infants (p10 to p21) prevented the development of benzodiazepine-resistant seizures and alleviated cognitive and behavioral deficits in adult Cdkl5 KO mice. In contrast, 12 days of OV350 treatment in adult Cdkl5 KO mice had limited ability to alleviate cognitive and behavioral deficits. In summary, this study demonstrates that enhancing KCC2 function may be a potential therapeutic target for CDD and other DEEs. However, early intervention during critical developmental windows is crucial for optimal outcomes.

neuroscience↗

bioRxiv2025

Neuroactive steroids activate membrane progesterone receptors to induce sex specific effects on protein kinase activity

Neuroactive steroids (NAS), which are synthesized in the brain from progesterone, exert potent effects on behavior and are used to treat postpartum depression, yet how these compounds induce sustained modifications in neuronal activity are ill-defined. Here, we examined the efficacy of NAS for membrane progesterone receptors (mPRs) {delta} and {varepsilon}, members of a family of GPCRs for progestins that are expressed in the CNS. NAS increase PKC activity via Gq activation of mPR{delta} with EC50s between 3-11nM. In contrast, they activate Gs via mPR{varepsilon} to potentiate PKA activity with similar potencies. NAS also induced rapid internalization of only mPR{delta}. In the forebrain of female mice, mPR{delta} expression levels were 8-fold higher than males. Consistent with this, activation of PKC by NAS was evident in acute brain slices from female mice. Collectively, our results suggests that NAS may exert sex-specific effects on intracellular signaling in the brain via activation of mPRs.

neuroscience↗

bioRxiv2023

Estradiol regulates local synthesis of synaptic proteome via sex-specific mechanisms.

Estrogens, specifically 17{beta}-estradiol (estradiol), can modulate synaptic function by regulating the expression and localisation of synaptic proteins. However, the mechanisms underlying estradiols regulation of synaptic protein expression, and whether if they occur in a sex specific manner, is not well understood. In this study, using sex-specific hippocampal slice cultures and mixed-sex primary hippocampal neurons, we investigated whether local protein synthesis is required for estradiol- induced synaptic protein expression. Estradiol rapidly increased the rate of protein synthesis and the number of actively translating ribosomes along dendrites and near synapses in both male and female hippocampal neurons. Importantly, these effects occurred independently of gene transcription. Moreover, estradiol also increased the abundance of nascent proteins localised to synapses, independently of gene transcription. Specifically, estradiol increased the synaptic expression of GluN2B- containing N-methyl-D-aspartate receptors and PSD-95 in male and female hippocampus. Mechanistically, mTOR signalling was required for estradiol-induced increases in overall local protein synthesis only in male but not female hippocampus. Consistent with this, mTOR signalling mediated estradiol increases in GluN2B in male, but not female, hippocampus. Conversely, mTOR inhibition, blocked estradiol-induced increased PSD-95 expression in both male and female hippocampus. Collectively, these data suggest that the rapid modulation of local protein synthesis by estradiol is required for changes in the synaptic proteome in male and female hippocampus, and that the requirement of the mTOR signalling pathway in these effects occur in both a sex-specific and protein-dependent manner, with this signalling pathway have a greater role in male compared to female hippocampus.

neuroscience↗

bioRxiv2021

Opposing roles of p38α phosphorylation and arginine methylation in driving TDP-43 proteinopathy.

Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disorder typically characterized by insoluble inclusions of hyperphosphorylated TDP-43. The mechanisms underlying toxic TDP-43 accumulation are not understood. Persistent activation of p38 mitogen-activated protein kinase (MAPK) is implicated in ALS. However, it is unclear how p38 MAPK affects TDP-43 proteinopathy. Here, we demonstrate that inhibition of p38 MAPK reduces pathological TDP-43 phosphorylation, aggregation, cytoplasmic mislocalization, and neurotoxicity. We establish that p38 MAPK phosphorylates TDP-43 at pathological serine 409/410 (S409/S410) and serine 292 (S292), which reduces TDP-43 liquid-liquid phase separation (LLPS) but allows pathological TDP-43 aggregation. Moreover, we show that protein arginine methyltransferase 1 methylates TDP-43 at R293. Importantly, S292 phosphorylation reduces R293 methylation, and R293 methylation reduces S409/S410 phosphorylation. R293 methylation permits TDP-43 LLPS and reduces pathological TDP-43 aggregation. Thus, strategies to reduce p38-mediated TDP-43 phosphorylation and promote R293 methylation could have therapeutic utility for ALS and related TDP-43 proteinopathies.

molecular biology↗

bioRxiv2020

KCC2 is required for the survival of mature neurons but not for their development

The K+/Cl- co-transporter KCC2 (SLC12A5) allows mature neurons in the CNS to maintain low intracellular Cl- levels that are critical in mediating fast hyperpolarizing synaptic inhibition via type A {gamma}-aminobutyric acid receptors GABAARs. In accordance with this, compromised KCC2 activity results in seizures but whether such deficits directly contribute to the subsequent changes in neuronal viability that lead to epileptogenesis, remains to be assessed. Canonical hyperpolarizing GABAAR currents develop postnatally which reflect a progressive increase in KCC2 expression levels and activity. To investigate the role that KCC2 plays in regulating neuronal viability and architecture we have conditionally ablated KCC2 expression in developing and mature neurons. Decreasing KCC2 expression resulted in the rapid activation of the extrinsic apoptotic pathway, in mature hippocampal neurons. Intriguingly, direct pharmacological inhibition of KCC2 in mature neurons resulted in the rapid activation of the extrinsic apoptotic pathway. In contrast, ablating KCC2 expression in immature neurons had no discernable effects on their subsequent development, arborization or dendritic structure. However ablating KCC2 expression in immature neurons was sufficient to prevent the subsequent postnatal development of hyperpolarizing GABAAR currents. Collectively, our results demonstrate that KCC2 plays a critical role in neuronal survival by limiting apoptosis, and mature neurons are highly sensitive to loss of KCC2 function. In contrast KCC2 appears to play a minimal role in mediating neuronal development or architecture.

neuroscience↗

bioRxiv2020

Isolation and characterization of multi-protein complexes enriched in the K-Cl co-transporter 2 from brain plasma membranes

Kcc2 plays a critical role in determining the efficacy of synaptic inhibition, however, the cellular mechanism neurons use to regulate its membrane trafficking, stability and activity are ill-defined. To address these issues, we used affinity purification to isolate stable multi-protein complexes of Kcc2 from the plasma membrane of murine forebrain. We resolved these using Blue-native polyacrylamide gel electrophoresis (BN-PAGE) coupled to LC-MS/MS. Purified Kcc2 migrated as distinct molecular species of 300, 600 and 800 kDa following BN-PAGE. In excess of 90% coverage of the soluble N and C-termini of Kcc2 was obtained. The 300kDa species largely contained Kcc2, which is consistent with a dimeric quaternary structure for this transporter. Intriguingly, lower levels of Kcc1 were also found in this species suggesting the existence of "mixed" Kcc2/Kcc1 heterodimers. The 600 and 800 kDa species represented stable multi-protein complexes of Kcc2. We identified a set of novel structural, ion transporting and signaling protein interactors, that are present at both excitatory and inhibitory synapses, consistent with the proposed association of Kcc2. These included spectrins, ankyrins, and the IP3 receptor. We also identified interactors more directly associated with phosphorylation; Akap5 and Lmtk3. Finally, we used LC-MS/MS on highly purified endogenous plasma membrane Kcc2 to detect phosphorylation sites. We detected 11 sites with high confidence, including known and novel sites. Collectively our experiments demonstrate that Kcc2 is associated with components of the neuronal cytoskeleton and signaling molecules that may act to regulate transporter membrane trafficking, stability, and activity.

neuroscience↗

bioRxiv2020

The K-Cl co-transporter 2 is a point of convergence for multiple autism spectrum disorder and epilepsy risk gene products.

KCC2 plays a critical role in determining the efficacy of synaptic inhibition and deficits in its activity lead to epilepsy and neurodevelopmental delay. Here we use unbiased proteomic analyses to demonstrate that KCC2 forms stable protein complexes in the neuronal plasma membrane with 96 autism and/or epilepsy risk gene (ASD/Epi) products including ANKB, ANKG, CNTN1, ITPR1, NCKAP1, SCN2A, SHANK3, SPTAN1, and SPTBN1. Many of these proteins are also targets of Fragile-X mental retardation protein (FMRP), the inactivation of which is the leading monogenic cause of autism. Accordingly, the expression of a subset of these KCC2-binding partners was decreased in Fmr1 knockout mice. Fmr1 knockout compromised KCC2 phosphorylation, a key regulatory mechanism for transporter activity and the postnatal development of GABAergic inhibition. Thus, KCC2 is a point of convergence for multiple ASD/Epi risk genes and therapies targeting this transporter may have broad utility in alleviating these heterogeneous disorders and their associated epilepsies.

neuroscience↗

bioRxiv2018

Brain neurosteroids are natural anxiolytics targeting α2 subunit γ-aminobutyric acid type-A receptors

Neurosteroids are naturally-occurring molecules in the brain that modulate neurotransmission. They are physiologically important since disrupting their biosynthesis precipitates neurological disorders, such as anxiety and depression. The endogenous neurosteroids, allopregnanolone and tetrahydro-deoxycorticosterone are derived from sex and stress hormones respectively, and exhibit therapeutically-useful anxiolytic, analgesic, sedative, anticonvulsant and antidepressant properties. Their main target is the {gamma}-aminobutyric acid type-A inhibitory neurotransmitter receptor (GABAAR), whose activation they potentiate. However, whether specific GABAAR isoforms and neural circuits differentially mediate endogenous neurosteroid effects is unknown. By creating a knock-in mouse that removes neurosteroid potentiation from 2-GABAAR subunits, we reveal that this isoform is a key target for neurosteroid modulation of phasic and tonic inhibition, and is essential for the anxiolytic role of endogenous neurosteroids, but not for their anti-depressant or analgesic properties. Overall, 2-GABAAR targeting neurosteroids may act as selective anxiolytics for the treatment of anxiety disorders, providing new therapeutic opportunities for drug development.

neuroscience↗