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Cytoplasmic mislocalization of RNA splicing factors and aberrant neuronal gene splicing in TDP-43 transgenic pig brain.

Wang G, Yang H, Yan S, Wang CE, Liu X, Zhao B, Ouyang Z, Yin P, Liu Z, Zhao Y, Liu T, Fan N, Guo L, Li S, Li XJ, Lai L - Mol Neurodegener (2015)

Bottom Line: We found that transgenic TDP-43 is also distributed in the cytoplasm of neuronal cells in the spinal cord and brain.The cytoplasmic localization of PSF and NeuN as well as abnormal PSF-related neuronal RNA splicing was also found in ALS patient brains.Our findings from a large mammalian model suggest that cytoplasmic mutant TDP-43 could reduce the nuclear function of RNA splicing factors, contributing to neuropathology.

View Article: PubMed Central - PubMed

Affiliation: State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, 100101, China. ghwang85@gmail.com.

ABSTRACT

Background: TAR DNA-binding protein 43 (TDP-43) is a nuclear protein, but it is redistributed in the neuronal cytoplasm in both amyotrophic lateral sclerosis (ALS) and frontotemporal lobar degeneration (FTLD). Because small transgenic animal models often lack cytoplasmic TDP-43, how the cytoplasmic accumulation of TDP-43 contributes to these diseases remains unclear. The current study is aimed at studying the mechanism of cytoplasmic pathology of TDP-43.

Results: We established transgenic pigs expressing mutant TDP-43 (M337V). This pig model shows severe phenotypes and early death. We found that transgenic TDP-43 is also distributed in the cytoplasm of neuronal cells in the spinal cord and brain. Transgenic TDP-43 interacts with PSF, an RNA splicing factor that associates with NeuN to regulate neuronal RNA splicing. The interaction of TDP-43, PSF and NeuN causes PSF and NeuN mislocalize into the neuronal cytoplasm in transgenic pigs. Consistently, abnormal PSF-related neuronal RNA splicing is seen in TDP-43 transgenic pigs. The cytoplasmic localization of PSF and NeuN as well as abnormal PSF-related neuronal RNA splicing was also found in ALS patient brains.

Conclusion: Our findings from a large mammalian model suggest that cytoplasmic mutant TDP-43 could reduce the nuclear function of RNA splicing factors, contributing to neuropathology.

No MeSH data available.


Related in: MedlinePlus

Progressive phenotypes of transgenic TDP-43 pigs. a Body weight reduction in different transgenic TDP-43 pigs at different ages. b Body weight (mean ± SE) of non-transgenic and transgenic TDP-43 pigs at 3, 4, 9 and 10 months of age (n = 5 for non-TG (Control) and n = 5 for TDP-43 transgenic pigs (TG)). * p < 0.05; ** p < 0.01. c Western blots analysis of ear tissues showing the expression of transgenic TDP-43 pigs that were monitored for their body weights. d Survival plot showing that expression of mutant TDP-43 caused early death of TDP-43 transgenic (TG) pigs (n = 12 for non-TG (Control) and n = 27 for TG). e Photographs of representative non-transgenic (Control) and TDP-43 transgenic pig (TG-16, 18, 24) at 9 months of age. f Summary of some transgenic pigs for their genotypes and phenotypes. C: Genotype is non-transgenic with the endogenous copies of pig TDP-43
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Fig2: Progressive phenotypes of transgenic TDP-43 pigs. a Body weight reduction in different transgenic TDP-43 pigs at different ages. b Body weight (mean ± SE) of non-transgenic and transgenic TDP-43 pigs at 3, 4, 9 and 10 months of age (n = 5 for non-TG (Control) and n = 5 for TDP-43 transgenic pigs (TG)). * p < 0.05; ** p < 0.01. c Western blots analysis of ear tissues showing the expression of transgenic TDP-43 pigs that were monitored for their body weights. d Survival plot showing that expression of mutant TDP-43 caused early death of TDP-43 transgenic (TG) pigs (n = 12 for non-TG (Control) and n = 27 for TG). e Photographs of representative non-transgenic (Control) and TDP-43 transgenic pig (TG-16, 18, 24) at 9 months of age. f Summary of some transgenic pigs for their genotypes and phenotypes. C: Genotype is non-transgenic with the endogenous copies of pig TDP-43

Mentions: Newborn transgenic TDP-43 pigs appeared as normal at birth as non-transgenic pigs. However, they started to gain less body weight from 3 months after birth compared to non-transgenic pigs (Fig. 2a and b). The extent of body weight loss appears to be correlated with the expression levels of TDP-43 in pig ear tissues (Fig. 2c). Many transgenic TDP-43 pigs die earlier starting at the age of 4–5 months, and 85 % (21/27) of the TDP-43 transgenic pigs died within one year (Fig. 2d). As a result of gaining considerable less body weight during development, the transgenic TDP-43 pigs often displayed loose skin characterized by wrinkled and sagging skin on their bodies (Fig. 2e). We previously established ALS pigs expressing mutant SOD1, which grew normally without body weight loss but showed an obvious running defect on a treadmill [27]. Like these ALS transgenic pigs, the TDP-43 transgenic pigs also showed progressive weakness and limb movement defects (Fig. 2f). However, following the training for the treadmill test, some TDP-43 pigs died, which did not allow us to use the treadmill to obtain quantified data of the limb movement impairment for TDP-43 pigs. Therefore, we used the surviving TDP-43 pigs, not including those that died right after treadmill test, to assess the growth, life span, and motor deficit of TDP-43 pigs. We found that there was the progressive reduction in the body weight and that transgenic TDP-43 pigs died earlier than non-transgenic pigs. The shorter life span and the more severe motor deficit in TDP-43 pigs than those of our previously reported transgenic SOD1 pigs [27] suggest that mutant TDP-43 elicits more toxicity than mutant SOD1 in transgenic pigs.Fig. 2


Cytoplasmic mislocalization of RNA splicing factors and aberrant neuronal gene splicing in TDP-43 transgenic pig brain.

Wang G, Yang H, Yan S, Wang CE, Liu X, Zhao B, Ouyang Z, Yin P, Liu Z, Zhao Y, Liu T, Fan N, Guo L, Li S, Li XJ, Lai L - Mol Neurodegener (2015)

Progressive phenotypes of transgenic TDP-43 pigs. a Body weight reduction in different transgenic TDP-43 pigs at different ages. b Body weight (mean ± SE) of non-transgenic and transgenic TDP-43 pigs at 3, 4, 9 and 10 months of age (n = 5 for non-TG (Control) and n = 5 for TDP-43 transgenic pigs (TG)). * p < 0.05; ** p < 0.01. c Western blots analysis of ear tissues showing the expression of transgenic TDP-43 pigs that were monitored for their body weights. d Survival plot showing that expression of mutant TDP-43 caused early death of TDP-43 transgenic (TG) pigs (n = 12 for non-TG (Control) and n = 27 for TG). e Photographs of representative non-transgenic (Control) and TDP-43 transgenic pig (TG-16, 18, 24) at 9 months of age. f Summary of some transgenic pigs for their genotypes and phenotypes. C: Genotype is non-transgenic with the endogenous copies of pig TDP-43
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Related In: Results  -  Collection

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Fig2: Progressive phenotypes of transgenic TDP-43 pigs. a Body weight reduction in different transgenic TDP-43 pigs at different ages. b Body weight (mean ± SE) of non-transgenic and transgenic TDP-43 pigs at 3, 4, 9 and 10 months of age (n = 5 for non-TG (Control) and n = 5 for TDP-43 transgenic pigs (TG)). * p < 0.05; ** p < 0.01. c Western blots analysis of ear tissues showing the expression of transgenic TDP-43 pigs that were monitored for their body weights. d Survival plot showing that expression of mutant TDP-43 caused early death of TDP-43 transgenic (TG) pigs (n = 12 for non-TG (Control) and n = 27 for TG). e Photographs of representative non-transgenic (Control) and TDP-43 transgenic pig (TG-16, 18, 24) at 9 months of age. f Summary of some transgenic pigs for their genotypes and phenotypes. C: Genotype is non-transgenic with the endogenous copies of pig TDP-43
Mentions: Newborn transgenic TDP-43 pigs appeared as normal at birth as non-transgenic pigs. However, they started to gain less body weight from 3 months after birth compared to non-transgenic pigs (Fig. 2a and b). The extent of body weight loss appears to be correlated with the expression levels of TDP-43 in pig ear tissues (Fig. 2c). Many transgenic TDP-43 pigs die earlier starting at the age of 4–5 months, and 85 % (21/27) of the TDP-43 transgenic pigs died within one year (Fig. 2d). As a result of gaining considerable less body weight during development, the transgenic TDP-43 pigs often displayed loose skin characterized by wrinkled and sagging skin on their bodies (Fig. 2e). We previously established ALS pigs expressing mutant SOD1, which grew normally without body weight loss but showed an obvious running defect on a treadmill [27]. Like these ALS transgenic pigs, the TDP-43 transgenic pigs also showed progressive weakness and limb movement defects (Fig. 2f). However, following the training for the treadmill test, some TDP-43 pigs died, which did not allow us to use the treadmill to obtain quantified data of the limb movement impairment for TDP-43 pigs. Therefore, we used the surviving TDP-43 pigs, not including those that died right after treadmill test, to assess the growth, life span, and motor deficit of TDP-43 pigs. We found that there was the progressive reduction in the body weight and that transgenic TDP-43 pigs died earlier than non-transgenic pigs. The shorter life span and the more severe motor deficit in TDP-43 pigs than those of our previously reported transgenic SOD1 pigs [27] suggest that mutant TDP-43 elicits more toxicity than mutant SOD1 in transgenic pigs.Fig. 2

Bottom Line: We found that transgenic TDP-43 is also distributed in the cytoplasm of neuronal cells in the spinal cord and brain.The cytoplasmic localization of PSF and NeuN as well as abnormal PSF-related neuronal RNA splicing was also found in ALS patient brains.Our findings from a large mammalian model suggest that cytoplasmic mutant TDP-43 could reduce the nuclear function of RNA splicing factors, contributing to neuropathology.

View Article: PubMed Central - PubMed

Affiliation: State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, 100101, China. ghwang85@gmail.com.

ABSTRACT

Background: TAR DNA-binding protein 43 (TDP-43) is a nuclear protein, but it is redistributed in the neuronal cytoplasm in both amyotrophic lateral sclerosis (ALS) and frontotemporal lobar degeneration (FTLD). Because small transgenic animal models often lack cytoplasmic TDP-43, how the cytoplasmic accumulation of TDP-43 contributes to these diseases remains unclear. The current study is aimed at studying the mechanism of cytoplasmic pathology of TDP-43.

Results: We established transgenic pigs expressing mutant TDP-43 (M337V). This pig model shows severe phenotypes and early death. We found that transgenic TDP-43 is also distributed in the cytoplasm of neuronal cells in the spinal cord and brain. Transgenic TDP-43 interacts with PSF, an RNA splicing factor that associates with NeuN to regulate neuronal RNA splicing. The interaction of TDP-43, PSF and NeuN causes PSF and NeuN mislocalize into the neuronal cytoplasm in transgenic pigs. Consistently, abnormal PSF-related neuronal RNA splicing is seen in TDP-43 transgenic pigs. The cytoplasmic localization of PSF and NeuN as well as abnormal PSF-related neuronal RNA splicing was also found in ALS patient brains.

Conclusion: Our findings from a large mammalian model suggest that cytoplasmic mutant TDP-43 could reduce the nuclear function of RNA splicing factors, contributing to neuropathology.

No MeSH data available.


Related in: MedlinePlus