Project description:Mutation in TDP-43 is causative to amyotrophic lateral sclerosis (ALS). TDP-43 is a multifunctional ribonucleoprotein and is reproted to regulate thousands of genes in neurons, but how astrocytes contribute to TDP-43 pathogenesis is not known. This study examined how mutant TDP-43 in astrocytes kills motor neurons and causes ALS phenotypes. Primary astrocytes were isolated from transgenic rats expressing mutant TDP-43 or from control rats without mutant TDP-43 expression. Cultured astrocytes were induced to express mutant human TDP-43 and their gene expression profiles were determined by microarray assays. Microarray analysis revealed that hundreds of genes were altered in astrocytes in response to mutant TDP-43 expression.
Project description:Mutation in TDP-43 is causative to amyotrophic lateral sclerosis (ALS). TDP-43 is a multifunctional ribonucleoprotein and is reproted to regulate thousands of genes in neurons, but how astrocytes contribute to TDP-43 pathogenesis is not known. This study examined how mutant TDP-43 in astrocytes kills motor neurons and causes ALS phenotypes. Primary astrocytes were isolated from transgenic rats expressing mutant TDP-43 or from control rats without mutant TDP-43 expression. Cultured astrocytes were induced to express mutant human TDP-43 and their gene expression profiles were determined by microarray assays. Microarray analysis revealed that hundreds of genes were altered in astrocytes in response to mutant TDP-43 expression. As mutant TDP-43 transgene is under the control of tetracycline-regulated pomoter elements (TRE), mutant TDP-43 expression is subjected to Doxycline regulation. Astrocytes isolated from GFAP-tTA/TRE-TDP43M337V rats were desiginated as M337V groups and astrocytes isolated from GFAP-tTA single transgenic rats were desiginated as tTA control groups. Total RNA was isolated from cultured astrocytes at varying times (3, 4, or 6 days after Dox withdrawal) after mutant TDP-43 was induced in astrocytes. Upon mutant TDP-43 induction in astroyctes, gene expression profiles in astroyctes were determined by Illumina Direct Hybridization Assay and compared between tTA and M337V groups at the varying time points of mutant TDP-43 induction.
Project description:The majority of patients with amyotrophic lateral sclerosis (ALS) have abnormal TDP-43 aggregates in the nucleus and/or cytosol of their surviving neurons and glia. Although accumulating evidence indicates that astroglial dysfunctions contribute to motor neuron degeneration in ALS, the normal physiological functions of TDP-43 in astrocytes are largely unknown and whether the loss of astroglial TDP-43 contributes to ALS remains to be clarified. Here, we showed that TDP-43 deleted astrocytes showed cell-autonomously enhanced GFAP immunoreactivity without affecting astrocyte or microglia proliferation. At the transcriptomic level, TDP-43 deleted astrocytes resemble the A1-reactive astrocytes and induce microglia to increase C1q expression. These astrocytic changes do not cause the loss of motor neurons in spinal cords or denervation at the neuromuscular junctions. In contrast, there was a selective reduction of mature oligodendrocytes, but not oligodendrocyte precursor cells, suggesting a tri-glial dysfunction mediated by TDP-43-deleted astrocytes. Mice with astroglial TDP-43 deletion developed motor, but not sensory, deficits. Taken together, our results demonstrate that TDP-43 is required to maintain the protective functions of astrocytes relevant to the development of motor deficits in mice.
Project description:TDP-43, a DNA/RNA binding protein involved in RNA transcription and splicing has been associated with the pathophysiology of neurodegenerative diseases, including ALS. However, the function of TDP-43 in motor neurons remains undefined. Here, we employ both gain- and loss-of-function approaches to determine roles of TDP-43 in motor neurons. Mice expressing human TDP-43 in neurons exhibited growth retardation and premature death that are characterized by abnormal intranuclear inclusions comprised of TDP-43 and Fused in Sarcoma (FUS), and massive accumulation of mitochondria in TDP-43-negative cytoplasmic inclusions in motor neurons, lack of mitochondria in motor axon terminals and immature neuromuscular junctions. Whereas elevated level of TDP-43 disrupts the normal nuclear distribution of Survival Motor Neuron (SMN)-associated Gemini of coiled bodies (GEMs) in motor neurons, its absence prevents the formation of GEMs in the nuclei of these cells. Moreover, transcriptome-wide deep sequencing analysis revealed that decrease in abundance of neurofilament transcripts contributed to the reduction of caliber of motor axons in TDP-43 mice. In concert, our findings indicate that TDP-43 participates in pathways critical for motor neuron physiology, including those that regulate the normal distributions of SMN-associated GEMs in the nucleus and mitochondria in the cytoplasm. Human TDP-43 coding region were inserted into pThy1.2 expression cassette and subsequently injected into C57BL/6;SJL hybrid mouse embryos to make human TDP-43 transgenic mice
Project description:TDP-43, a DNA/RNA binding protein involved in RNA transcription and splicing has been associated with the pathophysiology of neurodegenerative diseases, including ALS. However, the function of TDP-43 in motor neurons remains undefined. Here, we employ both gain- and loss-of-function approaches to determine roles of TDP-43 in motor neurons. Mice expressing human TDP-43 in neurons exhibited growth retardation and premature death that are characterized by abnormal intranuclear inclusions comprised of TDP-43 and Fused in Sarcoma (FUS), and massive accumulation of mitochondria in TDP-43-negative cytoplasmic inclusions in motor neurons, lack of mitochondria in motor axon terminals and immature neuromuscular junctions. Whereas elevated level of TDP-43 disrupts the normal nuclear distribution of Survival Motor Neuron (SMN)-associated Gemini of coiled bodies (GEMs) in motor neurons, its absence prevents the formation of GEMs in the nuclei of these cells. Moreover, transcriptome-wide deep sequencing analysis revealed that decrease in abundance of neurofilament transcripts contributed to the reduction of caliber of motor axons in TDP-43 mice. In concert, our findings indicate that TDP-43 participates in pathways critical for motor neuron physiology, including those that regulate the normal distributions of SMN-associated GEMs in the nucleus and mitochondria in the cytoplasm.
Project description:Edaravone is a free-radical scavenger drug that was recently approved for the treatment of amyo-trophic lateral sclerosis (ALS), a neurodegenerative disease. A pathological hallmark of ALS is the accumulation of ubiquitinated or phosphorylated aggregates of the 43-kDa transactive response DNA binding protein (TDP-43) within the cytoplasm of motor neurons. This study revealed the efficacy of edaravone in preventing neuronal cell death in a TDP-43 proteinopathy model and analyzed the molecular changes associated with the neuroprotection. The viability of the neuronal cells expressing TDP-43 was reduced by oxidative stress, and edaravone (≥10 μmol/L) protected in a concentration-dependent manner against the neurotoxic insult. Differential gene expression analysis revealed changes among pathways related to nuclear erythroid 2-related-factor (Nrf2)-mediated oxidative stress response in cells expressing TDP-43. In edaravone-treated cells express-ing TDP-43, significant changes in gene expression were also identified among Nrf2-oxidative re-sponse, unfolded protein response, and autophagy pathways. In addition, the expression of genes belonging to phosphatidylinositol metabolism pathways was modified. These findings suggest that the neuroprotective effect of edaravone involves the prevention of TDP-43 misfolding and en-hanced clearance of pathological TDP-43 in TDP-43 proteinopathy.
Project description:Aims: Loss of nuclear TDP-43 characterises sporadic and most familial forms of amyotrophic lateral sclerosis (ALS). TDP-43 (encoded by TARDBP) has multiple roles in RNA processing. We aimed to determine whether 1) RNA splicing dysregulation is present in lower motor neurons in ALS and in a motor neuron-like cell model, and 2) TARDBP mutations (mtTARDBP) are associated with aberrant RNA splicing using patient-derived fibroblasts. Methods: Affymetrix exon arrays were used to study mRNA expression and splicing in lower motor neurons obtained by laser capture microdissection of autopsy tissue from individuals with sporadic ALS and TDP-43 proteinopathy. Findings were confirmed by qRT-PCR and in NSC34 motor neuronal cells following shRNA-mediated TDP-43 depletion. Exon arrays and immunohistochemistry were used to study mRNA splicing and TDP-43 expression in fibroblasts from patients with mtTARDBP-associated, sporadic and mutant SOD1-associated ALS. Results: We found altered expression of spliceosome components in motor neurons and widespread aberrations of mRNA splicing that specifically affected genes involved in ribonucleotide binding. This was confirmed in TDP-43 depleted NSC34 cells. Fibroblasts with mtTARDBP showed loss of nuclear TDP-43 protein and demonstrated similar changes in splicing and gene expression, that were not present in fibroblasts from patients with sporadic or SOD1-related ALS. Conclusion: Loss of nuclear TDP-43 is associated with RNA processing abnormalities in ALS motor neurons, patient-derived cells with mtTARDBP, and following artificial TDP-43 depletion, suggesting that splicing dysregulation directly contributes to disease pathogenesis. Key functional pathways affected include those central to RNA metabolism. RNA was extracted from lower motor neurons obtained by laser capture microdissection from autopsy material from neurologically healthy controls (n=6) and cases of sporadic ALS (n=3) and ALS due to C9ORF72 mutations (n=3).
Project description:Aims: Loss of nuclear TDP-43 characterises sporadic and most familial forms of amyotrophic lateral sclerosis (ALS). TDP-43 (encoded by TARDBP) has multiple roles in RNA processing. We aimed to determine whether 1) RNA splicing dysregulation is present in lower motor neurons in ALS and in a motor neuron-like cell model, and 2) TARDBP mutations (mtTARDBP) are associated with aberrant RNA splicing using patient-derived fibroblasts. Methods: Affymetrix exon arrays were used to study mRNA expression and splicing in lower motor neurons obtained by laser capture microdissection of autopsy tissue from individuals with sporadic ALS and TDP-43 proteinopathy. Findings were confirmed by qRT-PCR and in NSC34 motor neuronal cells following shRNA-mediated TDP-43 depletion. Exon arrays and immunohistochemistry were used to study mRNA splicing and TDP-43 expression in fibroblasts from patients with mtTARDBP-associated, sporadic and mutant SOD1-associated ALS. Results: We found altered expression of spliceosome components in motor neurons and widespread aberrations of mRNA splicing that specifically affected genes involved in ribonucleotide binding. This was confirmed in TDP-43 depleted NSC34 cells. Fibroblasts with mtTARDBP showed loss of nuclear TDP-43 protein and demonstrated similar changes in splicing and gene expression, that were not present in fibroblasts from patients with sporadic or SOD1-related ALS. Conclusion: Loss of nuclear TDP-43 is associated with RNA processing abnormalities in ALS motor neurons, patient-derived cells with mtTARDBP, and following artificial TDP-43 depletion, suggesting that splicing dysregulation directly contributes to disease pathogenesis. Key functional pathways affected include those central to RNA metabolism. RNA was extracted from NSC34 motor neuronal cells depleted of TDP-43 by shRNA (n=4), treated with control shGFP (n=4), and treated with control shLuciferase (n=3).
Project description:Mislocalization of the predominantly nuclear RNA/DNA binding protein, TDP-43, occurs in motor neurons of ~95% of ALS patients, but the contribution of axonal TDP-43 to this fatal neurodegenerative disease is unclear. Here, we find TDP-43 accumulation in the axons of intra-muscular nerves from ALS patients, and in motor neurons and neuromuscular junctions(NMJs) of a mouse model with TDP-43 mislocalization. This leads to the formation of G3BP1- and TDP-43-positive RNA-granules in motor neuron axons, and to inhibition of local protein synthesis in axons and NMJs. Specifically, the axonal and synaptic levels of nuclear-encoded mitochondria proteins are reduced. Clearance of axonal TDP-43 restored local translation of the nuclear-encoded mitochondrial proteins and rescued TDP-43-derived axonal and NMJ toxicity. These findings suggest that targeting TDP-43 axonal gain of function may mediata therapeutic effect in ALS.
Project description:Aims: Loss of nuclear TDP-43 characterises sporadic and most familial forms of amyotrophic lateral sclerosis (ALS). TDP-43 (encoded by TARDBP) has multiple roles in RNA processing. We aimed to determine whether 1) RNA splicing dysregulation is present in lower motor neurons in ALS and in a motor neuron-like cell model, and 2) TARDBP mutations (mtTARDBP) are associated with aberrant RNA splicing using patient-derived fibroblasts. Methods: Affymetrix exon arrays were used to study mRNA expression and splicing in lower motor neurons obtained by laser capture microdissection of autopsy tissue from individuals with sporadic ALS and TDP-43 proteinopathy. Findings were confirmed by qRT-PCR and in NSC34 motor neuronal cells following shRNA-mediated TDP-43 depletion. Exon arrays and immunohistochemistry were used to study mRNA splicing and TDP-43 expression in fibroblasts from patients with mtTARDBP-associated, sporadic and mutant SOD1-associated ALS. Results: We found altered expression of spliceosome components in motor neurons and widespread aberrations of mRNA splicing that specifically affected genes involved in ribonucleotide binding. This was confirmed in TDP-43 depleted NSC34 cells. Fibroblasts with mtTARDBP showed loss of nuclear TDP-43 protein and demonstrated similar changes in splicing and gene expression, that were not present in fibroblasts from patients with sporadic or SOD1-related ALS. Conclusion: Loss of nuclear TDP-43 is associated with RNA processing abnormalities in ALS motor neurons, patient-derived cells with mtTARDBP, and following artificial TDP-43 depletion, suggesting that splicing dysregulation directly contributes to disease pathogenesis. Key functional pathways affected include those central to RNA metabolism. RNA was extracted from fibroblasts grown from neurologically healthy controls (n=6) and 3 groups of patients with ALS: 1) sporadic cases (n=6); 2) cases due to mutations of SOD1 (n=4); 3) cases due to mutations of TARDBP (n=3). The three ALS groups were compared to the controls.