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.

Vessel wall imaging in the diagnosis of antiphospholipid syndrome presenting as Moyamoya syndrome—A case report

The Neuroradiology Journal · 2024-04-15 · 4 citations

Objectives: We describe a case of anti-phospholipid syndrome (APLS) vasculopathy presenting with Moyamoya syndrome (MMS) and show the associated intracranial vessel wall MRI (VWI) findings. Methods: A 37-year-old-woman presented with acute onset dizziness and left-sided weakness. Neurologic exam revealed a left facial droop and left hemiparesis. She underwent a comprehensive laboratory work-up for stroke. Neuroimaging included a CT head, CT angiogram, VWI, and digital subtraction angiography. Results: Work-up revealed a triple-positive APLS antibody profile. CT of the head showed an acute right basal ganglia infarction and right frontal subarachnoid hemorrhage. CT angiogram revealed severe stenosis of the right internal carotid artery terminus in a Moyamoya pattern. Intracranial VWI showed long-segment concentric vessel wall thickening and homogeneous vessel wall enhancement and T2-hyperintense wall edema of the stenotic right ICA terminus, M1 middle cerebral artery, and A1 anterior cerebral artery. She was treated with long-term anticoagulation with warfarin and a right superficial temporal artery to middle cerebral artery bypass. Discussion: We present intracranial VWI features of vessel wall pathology in a patient with primary APLS presenting with MMS.

Reliability of Past Medical History in a Single Hospital Participating in Get With The Guidelines‐Stroke Registry

Journal of the American Heart Association · 2022-06-22

Background The GWTG (Get With The Guidelines)‐Stroke registry supports clinical research and quality improvement projects that often rely on past medical history elements, the reliability of which remains largely unknown. Here, we evaluated the reliability of specific past medical history elements in a local GWTG–Stroke data set, with particular attention to calculating the CHA 2 DS 2 ‐VASc score. Methods and Results A single‐center cohort was identified by querying the Hospital of the University of Pennsylvania’s GWTG IQVIA Registry Platform for patients admitted with acute ischemic stroke between January 2017 and December 2020, with a previously known history of atrial fibrillation. Demographics and previously known medical history elements were retrieved from the registry to calculate the CHA 2 DS 2 ‐VASc score. Five neurologists abstracted the same medical history elements from the health records. The κ statistics quantified the reliability of medical history elements and CHA 2 DS 2 ‐VASc score. Four hundred fifty‐three patients with acute ischemic stroke and previously known atrial fibrillation were included in the cohort. In comparison with manual reabstraction, registry‐based medical history elements were only moderately reliable: congestive heart failure (κ=0.53), hypertension (κ=0.42), diabetes (κ=0.80), prior stroke (κ=0.45), and vascular disease (κ=0.48). However, leveraging these variables to calculate the CHA 2 DS 2 ‐VASc score was more reliable (κ=0.73). Conclusions Previously known medical history elements in the GWTG‐Stroke registry were only modestly reliable in this single‐center study, suggesting caution should be exercised when relying on any individual history elements in registry‐based research. Combining these variables to calculate the CHA 2 DS 2 ‐VASc score was somewhat more reliable. Multicenter data are needed before assuming generalizability.

Heterozygous frameshift variants in HNRNPA2B1 cause early-onset oculopharyngeal muscular dystrophy

Nature Communications · 2022 · 43 citations

• Genetics
• Medicine
• Biology

Abstract Missense variants in RNA-binding proteins (RBPs) underlie a spectrum of disease phenotypes, including amyotrophic lateral sclerosis, frontotemporal dementia, and inclusion body myopathy. Here, we present ten independent families with a severe, progressive muscular dystrophy, reminiscent of oculopharyngeal muscular dystrophy (OPMD) but of much earlier onset, caused by heterozygous frameshift variants in the RBP hnRNPA2/B1. All disease-causing frameshift mutations abolish the native stop codon and extend the reading frame, creating novel transcripts that escape nonsense-mediated decay and are translated to produce hnRNPA2/B1 protein with the same neomorphic C-terminal sequence. In contrast to previously reported disease-causing missense variants in HNRNPA2B1 , these frameshift variants do not increase the propensity of hnRNPA2 protein to fibrillize. Rather, the frameshift variants have reduced affinity for the nuclear import receptor karyopherin β2, resulting in cytoplasmic accumulation of hnRNPA2 protein in cells and in animal models that recapitulate the human pathology. Thus, we expand the phenotypes associated with HNRNPA2B1 to include an early-onset form of OPMD caused by frameshift variants that alter its nucleocytoplasmic transport dynamics.

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

bioRxiv (Cold Spring Harbor Laboratory) · 2021 · 10 citations

• Cell biology
• Biology
• Chemistry

Abstract 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 p38α MAPK reduces pathological TDP-43 phosphorylation, aggregation, cytoplasmic mislocalization, and neurotoxicity. We establish that p38α 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 p38α-mediated TDP-43 phosphorylation and promote R293 methylation could have therapeutic utility for ALS and related TDP-43 proteinopathies.

Characterization of HNRNPA1 mutations defines diversity in pathogenic mechanisms and clinical presentation

JCI Insight · 2021 · 70 citations

• Biology
• Cell biology
• Genetics

Mutations in HNRNPA1 encoding heterogeneous nuclear ribonucleoprotein (hnRNP) A1 are a rare cause of amyotrophic lateral sclerosis (ALS) and multisystem proteinopathy (MSP). hnRNPA1 is part of the group of RNA-binding proteins (RBPs) that assemble with RNA to form RNPs. hnRNPs are concentrated in the nucleus and function in pre-mRNA splicing, mRNA stability, and the regulation of transcription and translation. During stress, hnRNPs, mRNA, and other RBPs condense in the cytoplasm to form stress granules (SGs). SGs are implicated in the pathogenesis of (neuro-)degenerative diseases, including ALS and inclusion body myopathy (IBM). Mutations in RBPs that affect SG biology, including FUS, TDP-43, hnRNPA1, hnRNPA2B1, and TIA1, underlie ALS, IBM, and other neurodegenerative diseases. Here, we characterize 4 potentially novel HNRNPA1 mutations (yielding 3 protein variants: *321Eext*6, *321Qext*6, and G304Nfs*3) and 2 known HNRNPA1 mutations (P288A and D262V), previously connected to ALS and MSP, in a broad spectrum of patients with hereditary motor neuropathy, ALS, and myopathy. We establish that the mutations can have different effects on hnRNPA1 fibrillization, liquid-liquid phase separation, and SG dynamics. P288A accelerated fibrillization and decelerated SG disassembly, whereas *321Eext*6 had no effect on fibrillization but decelerated SG disassembly. By contrast, G304Nfs*3 decelerated fibrillization and impaired liquid phase separation. Our findings suggest different underlying pathomechanisms for HNRNPA1 mutations with a possible link to clinical phenotypes.

Specific heterozygous frameshift variants in <i>hnRNPA2B1</i> cause early-onset oculopharyngeal muscular dystrophy

medRxiv · 2021-04-16 · 2 citations

Summary RNA-binding proteins (RBPs) are essential for post-transcriptional regulation and processing of RNAs. Pathogenic missense variants in RBPs underlie a spectrum of disease phenotypes, including amyotrophic lateral sclerosis, frontotemporal dementia, inclusion body myopathy, distal myopathy, and Paget’s disease of the bone. Here, we present ten independent families with a severe, progressive, early-onset muscular dystrophy, reminiscent of oculopharyngeal muscular dystrophy (OPMD), caused by heterozygous frameshift variants in the prion-like domain of hnRNPA2B1 . We found that in contrast with the previously reported missense variants, the frameshift hnRNPA2B1 variants do not promote, but rather decelerate the fibrillization of the protein. Importantly, the frameshift variants harbor altered nuclear-localization sequences and exhibit reduced affinity for the nuclear-import receptor, Karyopherin-β2, which promotes their cytoplasmic accumulation in cells and in animal models that recapitulate the human pathology. Thus, we expand the phenotypes associated with hnRNPA2B1 to include a severe, early-onset disease reminiscent of OPMD, caused by a distinct class of frameshift variants that alter its nucleocytoplasmic transport dynamics.

Polyglutamine (CAG) Intermediate Repeat Expansions in ATXN2 is Associated with a More Aggressive Form of ALS Across Multiple Independent Cohorts (2094)

Neurology · 2020-04-14 · 1 citations

Objective: To investigate the association of intermediate length poly CAG expansions in ATXN2 with functional disease progression in amyotrophic lateral sclerosis measured using the ALSFRS-R and respiratory vital capacity (SVC/FVC). Background: ALS is a heterogeneous neurodegenerative condition for which effective treatments are lacking. Multiple human genetic studies have identified intermediate repeat CAG expansions in ATXN2, as a significant risk factor for developing ALS [Elden 2010; Neuenschwander 2014; Sproviero 2017]. With the emergence of candidate disease-modifying ATXN2 therapies, including antisense oligonucleotides, it is critical to understand the association of intermediate CAG repeats with ALS disease progression. Design/Methods: We performed a retrospective multi-cohort analysis of 20 intermediate CAG (30–33) ATXN2 expansion cases and 640 non-expanded matched controls without a CAG expansion ( Results: Sex, baseline age, disease duration, site of onset (bulbar vs. limb) and baseline ALSFRS-R and vital capacity did not differ between intermediate and non-expanded cases within each cohort. Meta-analyses revealed that across cohorts, ALS patients with intermediate CAG repeats exhibited a faster slope of decline on ALSFRS-R (z=2.92; p=0.0035) and vital capacity (z=2.77; p=0.0056) relative to non-expanded disease controls. Conclusions: Our results build on the mounting evidence of the pathologic role of ATXN2 intermediate repeat mutations in ALS further supporting the therapeutic potential of targeting ATXN2 for the treatment of ALS. Disclosure: Dr. McMillan has received personal compensation for consulting, serving on a scientific advisory board, speaking, or other activities with Axon Advisors. Dr. McMillan has received research support from Biogen, Inc and Avanir Pharmaceuticals. Dr. Tsai has received personal compensation for consulting, serving on a scientific advisory board, speaking, or other activities with Biogen Inc. Dr. Tsai holds stock and/or stock options in Biogen Inc. which sponsored research in which Dr. Tsai was involved as an investigator. Dr. Tsai holds stock and/or stock options in Biogen Inc.. Dr. Hurt has received personal compensation for consulting, serving on a scientific advisory board, speaking, or other activities with Biogen Inc. Dr. Hurt holds stock and/or stock options in Biogen Inc which sponsored research in which Dr. Hurt was involved as an investigator. Dr. Wuu has received personal compensation for consulting, serving on a scientific advisory board, speaking, or other activities with Biogen Inc.. Dr. Wuu holds stock and/or stock options in Biogen Inc. which sponsored research in which Dr. Wuu was involved as an investigator. Dr. Ford has nothing to disclose. Dr. Van Deerlin has received research support from Asuragen. Dr. Elman has nothing to disclose. Yes - Amicus – Advisory Board; Amylyx – Advisory Board; Acceleron – Advisory BoardDr. McCluskey has nothing to disclose. Dr. Liu has received personal compensation for consulting, serving on a scientific advisory board, speaking, or other activities with Biogen Inc.. Dr. Chang has received personal compensation for consulting, serving on a scientific advisory board, speaking, or other activities with Employees of and hold stock/stock options in Biogen. Dr. Chang holds stock and/or stock options in Biogen, stock greater than 10K which sponsored research in which Dr. Chang was involved as an investigator. Dr. Rademakers has nothing to disclose. Dr. Van Blitterswijk has nothing to disclose. Dr. Sun has received personal compensation for consulting, serving on a scientific advisory board, speaking, or other activities with Biogen Inc.. Dr. Consortium has nothing to disclose. Dr. Consortium has nothing to disclose. Dr. Benatar has served on the AveXis Scientific Advisory Board ($2,151), Genentech Honorarium as visiting speaker ($1,000) The University of Miami has received funding from Biogen ($50K) and Orphazyme ($40K) in support of my ALS research program.Dr. Harms has received personal compensation for consulting, serving on a scientific advisory board, speaking, or other activities with Biogen, Sanofi, and Maze Therapeutics. Dr. Harms has received research support from Biogen. Dr. Currier has received personal compensation for consulting, serving on a scientific advisory board, speaking, or other activities with Biogen. Dr. Currier holds stock and/or stock options in Biogen Inc. which sponsored research in which Dr. Currier was involved as an investigator.

Mechanisms and Modifiers of Protein Misfolding and Toxicity Associated with Multisystem Proteinopathy

ScholarlyCommons (University of Pennsylvania) · 2017-01-01

Multisystem proteinopathy (MSP) is a degenerative syndrome incorporating features of inclusion body myopathy (IBM), Paget’s disease of bone (PDB), frontotemporal dementia (FTD), and amyotrophic lateral sclerosis (ALS) that is currently incurable and ultimately fatal. Missense mutations in the prion-like domains (PrLDs) of the genes encoding the RNA-binding proteins (RBPs) heterogeneous nuclear ribonucleoprotein (hnRNP) A1 (D262V) and hnRNPA2 (D290V) cause MSP. These MSP-linked mutations introduce a potent steric zipper into the PrLD and accelerate spontaneous hnRNPA1 and hnRNPA2 fibrillogenesis. However, the mechanism by which these variants of hnRNPA1 and hnRNPA2 cause disease is unknown. Here, we employ Saccharomyces cerevisiae as a model system to recapitulate the cellular phenotype seen in MSP patients and map the determinants of hnRNPA1 and hnRNPA2 toxicity and misfolding. We have also utilized a candidate gene approach and an unbiased gene deletion screen to identify genetic modifiers of hnRNPA1 and hnRNPA2 toxicity. Using a series of deletion and truncation constructs, we have determined that hnRNPA1 and hnRNPA2 require at least one intact RNA-recognition motif and a portion of the low complexity PrLD to confer toxicity. Thus, we propose a mechanism of toxicity that requires RNA binding and formation of cytoplasmic inclusions by hnRNPA1 or hnRNPA2. hnRNPA1 and hnRNPA2 form self-templating fibrils in vitro, which cannot occur in the absence of the PrLD. We identified forty gene deletions that suppressed the toxicity of hnRNPA1 and hnRNPA2, including RNP (ribonucleoprotein)-granule components (Sbp1, Lsm6, and Lsm7), molecular chaperones (Hsc82, Sti1, Sse1, and Ydj1), and spliceosome proteins (Lsm6, Lsm7, Prp18, and Bud31). In all cases, genetic suppressors of hnRNPA1 toxicity also suppressed hnRNPA2 toxicity, indicating mechanistic convergence. Importantly, only five genes from this list are known modifiers of FUS or TDP-43 toxicity in yeast. TDP-43 and FUS are also RBPs with PrLDs implicated in the pathogenesis of neurodegenerative disease. This lack of overlap in genetic modifiers suggests important mechanistic differences in the underpinnings of cellular toxicity mediated by hnRNPA1 and hnRNPA2 versus TDP-43 or FUS. By contrast, engineered variants of a protein disaggregase, Hsp104, that possess potentiated disaggregase activity suppressed the toxicity of TDP-43 and FUS in addition to hnRNPA1, hnRNPA2, and both MSP-linked mutant hnRNPs. Potentiated Hsp104 variants, therefore, represent a possibly broadly efficacious therapeutic that could be developed to combat a range of neurodegenerative phenotypes caused by RBPs with PrLDs. The toxicity suppressors that we have identified may ultimately have therapeutic implications for not only MSP patients, but also patients with sporadic ALS, FTD, IBM, and PDB. Future work should include investigation of existing small-molecule inhibitors, for example Hsp90 or Hsp70 inhibitors, that mimic the genetic deletions we have uncovered for potential therapeutic use.