Opposing roles of p38α-mediated phosphorylation and PRMT1-mediated arginine methylation in driving TDP-43 proteinopathy

Cell Reports · 2025-02-19 · 1 citations

Opposing roles of p38α-mediated phosphorylation and PRMT1-mediated arginine methylation in driving TDP-43 proteinopathy

Cell Reports · 2025-01-01 · 14 citations

Amyotrophic lateral sclerosis (ALS) is a devastating 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 show that p38α MAPK inhibition reduces pathological TDP-43 phosphorylation, aggregation, cytoplasmic mislocalization, and neurotoxicity. Remarkably, p38α MAPK inhibition mitigates aberrant TDP-43 phenotypes in diverse ALS patient-derived motor neurons. p38α MAPK phosphorylates TDP-43 at pathological S409/S410 and S292, which reduces TDP-43 liquid-liquid phase separation (LLPS) but allows pathological TDP-43 aggregation. Moreover, we establish that PRMT1 methylates TDP-43 at R293. Importantly, S292 phosphorylation reduces R293 methylation, and R293 methylation reduces S409/S410 phosphorylation. Notably, R293 methylation permits TDP-43 LLPS and reduces pathological TDP-43 aggregation. Thus, strategies to reduce p38α-mediated TDP-43 phosphorylation and promote PRMT1-mediated R293 methylation could have therapeutic utility for ALS and related TDP-43 proteinopathies.

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

bioRxiv (Cold Spring Harbor Laboratory) · 2025-01-25

Summary 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) δ and ε, members of a family of GPCRs for progestins that are expressed in the CNS. NAS increase PKC activity via G q activation of mPRδ with EC50s between 3-11nM. In contrast, they activate G s via mPRε to potentiate PKA activity with similar potencies. NAS also induced rapid internalization of only mPRδ. In the forebrain of female mice, mPRδ 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.

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

bioRxiv (Cold Spring Harbor Laboratory) · 2025-02-26 · 1 citations

Abstract 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 (GABA A R). 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.

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

iScience · 2025-04-06 · 1 citations

via mPRε to potentiate PKA activity with similar potencies. NAS also induced the rapid internalization of only mPRδ. In the forebrain of female mice, mPRδ expression levels were 8-fold higher than in males. Consistent with this, the activation of PKC by NAS was evident in acute brain slices from female mice. Collectively, our results suggest that NAS may exert sex-specific effects on intracellular signaling in the brain via the activation of mPRs.

The brain-specific kinase LMTK3 regulates neuronal excitability by decreasing KCC2-dependent neuronal Cl− extrusion

iScience · 2024-03-15 · 5 citations

<h2>Summary</h2> LMTK3 is a brain-specific transmembrane serine/threonine protein kinase that acts as a scaffold for protein phosphatase-1 (PP1). Although LMKT3 has been identified as a risk factor for autism and epilepsy, its physiological significance is unknown. Here, we demonstrate that LMTK3 copurifies and binds to KCC2, a neuron-specific K⁺/Cl⁻ transporter. KCC2 activity is essential for Cl⁻-mediated hyperpolarizing GABA_AR receptor currents, the unitary events that underpin fast synaptic inhibition. LMTK3 acts to promote the association of KCC2 with PP1 to promote the dephosphorylation of S940 within its C-terminal cytoplasmic domain, a process the diminishes KCC2 activity. Accordingly, acute inhibition of LMTK3 increases KCC2 activity dependent upon S940 and increases neuronal Cl⁻ extrusion. Consistent with this, LMTK3 inhibition reduced intrinsic neuronal excitability and the severity of seizure-like events <i>in vitro</i>. Thus, LMTK3 may have profound effects on neuronal excitability as an endogenous modulator of KCC2 activity.

The PDE4 inhibitor apremilast modulates ethanol responses in Gabrb1-S409A knock-in mice via PKA-dependent and independent mechanisms

Neuropharmacology · 2024-06-13 · 1 citations

A revised nomenclature for the lemur family of protein kinases

Communications Biology · 2024-01-08 · 6 citations

The lemur family of protein kinases has gained much interest in recent years as they are involved in a variety of cellular processes including regulation of axonal transport and endosomal trafficking, modulation of synaptic functions, memory and learning, and they are centrally placed in several intracellular signalling pathways. Numerous studies have also implicated role of the lemur kinases in the development and progression of a wide range of cancers, cystic fibrosis, and neurodegenerative diseases. However, parallel discoveries and inaccurate prediction of their kinase activity have resulted in a confusing and misleading nomenclature of these proteins. Herein, a group of international scientists with expertise in lemur family of protein kinases set forth a novel nomenclature to rectify this problem and ultimately help the scientific community by providing consistent information about these molecules.

Abstract 3636: Liver endothelium secreted LRG1 promotes metastatic colorectal cancer growth through the HER3/RSK/EIF4B AXIS

Cancer Research · 2023-04-04

Abstract Background: 25% of patients diagnosed with colorectal cancer (CRC) have liver metastasis at presentation, and ~80% of all metastatic CRC are developed in the liver. We previously reported that liver endothelial cells (ECs), a key component of the liver microenvironment, secrete LRG1 to promote CRC growth via activating human epidermal growth factor receptor (ERbB3, also known as HER3). However, we found that LRG1-induced HER3 activation is distinct from the canonical neuregulin 1 (NRG1)-induced HER3 pathway. The present study further validated LRG1 as a new HER3 ligand for promoting mCRC growth and elucidated the novel downstream signaling pathway induced by LRG1-HER3. Methods: We first measured the binding affinity between HER3 and LRG1 by Biolayer interferometry (BLI). We then used in vitro and in vivo xenograft approaches to determine the effect of LRG1 monoclonal antibody (15C4) on HER3 activation and CRC growth. To further determine the role of LRG1 in promoting CRC growth in the liver, we used murine CRC cells in a syngeneic orthotropic liver injection model to establish CRC allografts in the liver of LRG1−/− mice with systemic LRG1 knockout and wild-type siblings (LRG1+/+). We also performed unbiased phospho-MS analysis and subsequent validations to determine the downstream signaling pathway activated by LRG1-HER3. Results: We identified that LRG1 binds to HER3 with the affinity at ~100nM. The LRG1 antibody 15C4 completely attenuated LRG1-induced HER3 activation and in vitro and xenograft growth in vivo. Moreover, LRG1−/− mice with CRC allografts in the liver had 2 times longer overall survival than tumor-bearing LRG1+/+ mice. Lastly, unbiased -omics analysis identified eIF4-protein synthesis is significantly activated by LRG1. With target-specific inhibitors, we further determined that LRG1-HER3 activates the PI3K-PDK1-RSK1/3-eIF4 axis independent of AKT. Conclusions: We identified LRG1 as a novel HER3 ligand and demonstrated that the liver microenvironment-derived LRG1 plays a key oncogenic role in mCRC, by activating a novel RSK-eIF4 survival pathway. Our findings highlighted the potential of blocking LRG1-HER3 and involved downstream pathways for treating patients with mCRC. Citation Format: Moeez Ghani Rathore, Michelle Wright, Wei Huang, Derek Taylor, Yamu Li, Jordan Winter, Zhenghe Wang, John Greenwood, Stephen Moss, Rui Wang. Liver endothelium secreted LRG1 promotes metastatic colorectal cancer growth through the HER3/RSK/EIF4B AXIS. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 3636.

Molecular basis of selective amyloid‐β degrading enzymes in Alzheimer's disease

FEBS Journal · 2023-08-25 · 31 citations

The accumulation of the small 42-residue long peptide amyloid-β (Aβ) has been proposed as a major trigger for the development of Alzheimer's disease (AD). Within the brain, the concentration of Aβ peptide is tightly controlled through production and clearance mechanisms. Substantial experimental evidence now shows that reduced levels of Aβ clearance are present in individuals living with AD. This accumulation of Aβ can lead to the formation of large aggregated amyloid plaques-one of two detectable hallmarks of the disease. Aβ-degrading enzymes (ADEs) are major players in the clearance of Aβ. Stimulating ADE activity or expression, in order to compensate for the decreased clearance in the AD phenotype, provides a promising therapeutic target. It has been reported in mice that upregulation of ADEs can reduce the levels of Aβ peptide and amyloid plaques-in some cases, this led to improved cognitive function. Among several known ADEs, neprilysin (NEP), endothelin-converting enzyme-1 (ECE-1), insulin degrading enzyme (IDE) and angiotensin-1 converting enzyme (ACE) from the zinc metalloprotease family have been identified as important. These ADEs have the capacity to digest soluble Aβ which, in turn, cannot form the toxic oligomeric species. While they are known for their amyloid degradation, they exhibit complexity through promiscuous nature and a broad range of substrates that they can degrade. This review highlights current structural and functional understanding of these key ADEs, giving some insight into the molecular interactions that leads to the hydrolysis of peptide substrates, the crucial tasks performed by them and the potential for therapeutic use in the future.