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Interaction of transactive response DNA binding protein 43 with nuclear factor κB in mild cognitive impairment with episodic memory deficits.

Ohta Y, Tremblay C, Schneider JA, Bennett DA, Calon F, Julien JP - Acta Neuropathol Commun (2014)

Bottom Line: Recently, TDP-43 was reported to contribute to pathogenesis in amyotrophic lateral sclerosis through its interaction with p65 nuclear factor κB (NF-κB) resulting in abnormal hyperactivation of this signaling pathway in motor neurons.These MCI-p cases exhibited high expression levels of soluble TDP-43, p65, phosphorylated p65 and low expression levels of β-amyloid 40 when compared to AD or NCI cases.From these results, we propose that enhanced NF-κB activation due to TDP-43 and p65 interaction may contribute to neuronal dysfunction in MCI individuals with episodic memory deficits.

View Article: PubMed Central - HTML - PubMed

Affiliation: Research Centre of Institut universitaire en santé mentale de Québec, Québec, QC, Canada. jean-pierre.julien@fmed.ulaval.ca.

ABSTRACT

Introduction: Transactive response DNA binding protein 43 (TDP-43) is detected in pathological inclusions in many cases of Alzheimer's disease (AD) and mild cognitive impairment (MCI), but its pathological role in AD and MCI remains unknown. Recently, TDP-43 was reported to contribute to pathogenesis in amyotrophic lateral sclerosis through its interaction with p65 nuclear factor κB (NF-κB) resulting in abnormal hyperactivation of this signaling pathway in motor neurons. Hence, we investigated the interaction of TDP-43 with p65 in the temporal cortex of subjects with a clinical diagnosis of MCI (n = 12) or AD (n = 12) as well as of age-matched controls with no cognitive impairment (NCI, n = 12).

Results: Immunoprecipitation and immunofluorescence approaches revealed a robust interaction of TDP-43 with p65 in the nucleus of temporal lobe neurons in four individuals with MCI (named MCI-p). These MCI-p cases exhibited high expression levels of soluble TDP-43, p65, phosphorylated p65 and low expression levels of β-amyloid 40 when compared to AD or NCI cases. The analysis of cognitive performance tests showed that MCI-p individuals presented intermediate deficits of global cognition and episodic memory between those of AD cases and of NCI cases and MCI cases with no interaction of TDP-43 with p65.

Conclusions: From these results, we propose that enhanced NF-κB activation due to TDP-43 and p65 interaction may contribute to neuronal dysfunction in MCI individuals with episodic memory deficits. Accordingly, treatment with inhibitors of NF-κB activation may be considered for MCI individuals with episodic memory deficits.

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Full-length TDP-43 interacts with p65 NF-κB in the temporal cortex of four individuals with mild cognitive impairment (MCI). a The presence of phosphorylated p65 NF-κB at ser536 and accumulation of p65 and full-length of TDP-43 in TBS-soluble fraction from the temporal cortex of individuals with MCI. Protein extracts from the temporal cortex of individuals with no obvious cognitive impairment (NCI; N, n = 12), MCI (M, n = 12) or Alzheimer’s disease (AD; A, n = 12) were subjected to SDS-PAGE and immunoblotting with the indicated antibodies. Actin was used as a loading control. b, c Interaction of TDP-43 with p65 in TBS-soluble fraction from the temporal cortex of four individuals with MCI (Subjects 8, 15, 17 and 23), one individual with AD (Subject 2) and four individuals with NCI (Subjects 7, 14, 21 and 29). Protein extracts from the temporal cortex of individuals with NCI, MCI or AD were used for immunoprecipitation (IP) with anti-p65 polyclonal antibody (b) or anti-TDP-43 polyclonal antibody (c). Immunoprecipitates were subjected to SDS-PAGE and immunoblotting with the indicated antibodies. Number of Subjects 8, 15, 17 and 23 is written in red color.
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Figure 1: Full-length TDP-43 interacts with p65 NF-κB in the temporal cortex of four individuals with mild cognitive impairment (MCI). a The presence of phosphorylated p65 NF-κB at ser536 and accumulation of p65 and full-length of TDP-43 in TBS-soluble fraction from the temporal cortex of individuals with MCI. Protein extracts from the temporal cortex of individuals with no obvious cognitive impairment (NCI; N, n = 12), MCI (M, n = 12) or Alzheimer’s disease (AD; A, n = 12) were subjected to SDS-PAGE and immunoblotting with the indicated antibodies. Actin was used as a loading control. b, c Interaction of TDP-43 with p65 in TBS-soluble fraction from the temporal cortex of four individuals with MCI (Subjects 8, 15, 17 and 23), one individual with AD (Subject 2) and four individuals with NCI (Subjects 7, 14, 21 and 29). Protein extracts from the temporal cortex of individuals with NCI, MCI or AD were used for immunoprecipitation (IP) with anti-p65 polyclonal antibody (b) or anti-TDP-43 polyclonal antibody (c). Immunoprecipitates were subjected to SDS-PAGE and immunoblotting with the indicated antibodies. Number of Subjects 8, 15, 17 and 23 is written in red color.

Mentions: TBS-soluble fraction of temporal cortex of subjects with NCI, MCI and AD was used for immunoblotting and coimmunoprecipitation experiments. Immunoblotting experiments revealed that the levels of both TDP-43 and p65 were elevated in 5 individuals with MCI (Subjects 8, 12, 15, 17 and 23), 2 individuals with AD (Subjects 2 and 13) and 4 individuals with NCI (Subjects 7, 14, 21 and 29) (Figure 1a). It is established that activation of p65 is associated with its phosphorylation [39]. Moreover, an elevation of phosphorylated p65 at ser536 can be achieved by overexpression of TDP-43 in microglial cells after stimulation with LPS or H2O2[23]. As shown in Figure 1a, the signal of phosphorylated p65 at ser536 was quite weak in post-mortem tissue of temporal cortex from most subjects. Nonetheless, phosphorylated p65 was detectable by immunoblotting in 4 individuals with MCI (Subjects 8, 12, 15 and 23) and 1 individual with AD (Subject 28). Thus, using χ2test, the frequency of positive phospho-p65 were increased in MCI (χ2 = 6.039, p = 0.049).


Interaction of transactive response DNA binding protein 43 with nuclear factor κB in mild cognitive impairment with episodic memory deficits.

Ohta Y, Tremblay C, Schneider JA, Bennett DA, Calon F, Julien JP - Acta Neuropathol Commun (2014)

Full-length TDP-43 interacts with p65 NF-κB in the temporal cortex of four individuals with mild cognitive impairment (MCI). a The presence of phosphorylated p65 NF-κB at ser536 and accumulation of p65 and full-length of TDP-43 in TBS-soluble fraction from the temporal cortex of individuals with MCI. Protein extracts from the temporal cortex of individuals with no obvious cognitive impairment (NCI; N, n = 12), MCI (M, n = 12) or Alzheimer’s disease (AD; A, n = 12) were subjected to SDS-PAGE and immunoblotting with the indicated antibodies. Actin was used as a loading control. b, c Interaction of TDP-43 with p65 in TBS-soluble fraction from the temporal cortex of four individuals with MCI (Subjects 8, 15, 17 and 23), one individual with AD (Subject 2) and four individuals with NCI (Subjects 7, 14, 21 and 29). Protein extracts from the temporal cortex of individuals with NCI, MCI or AD were used for immunoprecipitation (IP) with anti-p65 polyclonal antibody (b) or anti-TDP-43 polyclonal antibody (c). Immunoprecipitates were subjected to SDS-PAGE and immunoblotting with the indicated antibodies. Number of Subjects 8, 15, 17 and 23 is written in red color.
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
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getmorefigures.php?uid=PMC4230634&req=5

Figure 1: Full-length TDP-43 interacts with p65 NF-κB in the temporal cortex of four individuals with mild cognitive impairment (MCI). a The presence of phosphorylated p65 NF-κB at ser536 and accumulation of p65 and full-length of TDP-43 in TBS-soluble fraction from the temporal cortex of individuals with MCI. Protein extracts from the temporal cortex of individuals with no obvious cognitive impairment (NCI; N, n = 12), MCI (M, n = 12) or Alzheimer’s disease (AD; A, n = 12) were subjected to SDS-PAGE and immunoblotting with the indicated antibodies. Actin was used as a loading control. b, c Interaction of TDP-43 with p65 in TBS-soluble fraction from the temporal cortex of four individuals with MCI (Subjects 8, 15, 17 and 23), one individual with AD (Subject 2) and four individuals with NCI (Subjects 7, 14, 21 and 29). Protein extracts from the temporal cortex of individuals with NCI, MCI or AD were used for immunoprecipitation (IP) with anti-p65 polyclonal antibody (b) or anti-TDP-43 polyclonal antibody (c). Immunoprecipitates were subjected to SDS-PAGE and immunoblotting with the indicated antibodies. Number of Subjects 8, 15, 17 and 23 is written in red color.
Mentions: TBS-soluble fraction of temporal cortex of subjects with NCI, MCI and AD was used for immunoblotting and coimmunoprecipitation experiments. Immunoblotting experiments revealed that the levels of both TDP-43 and p65 were elevated in 5 individuals with MCI (Subjects 8, 12, 15, 17 and 23), 2 individuals with AD (Subjects 2 and 13) and 4 individuals with NCI (Subjects 7, 14, 21 and 29) (Figure 1a). It is established that activation of p65 is associated with its phosphorylation [39]. Moreover, an elevation of phosphorylated p65 at ser536 can be achieved by overexpression of TDP-43 in microglial cells after stimulation with LPS or H2O2[23]. As shown in Figure 1a, the signal of phosphorylated p65 at ser536 was quite weak in post-mortem tissue of temporal cortex from most subjects. Nonetheless, phosphorylated p65 was detectable by immunoblotting in 4 individuals with MCI (Subjects 8, 12, 15 and 23) and 1 individual with AD (Subject 28). Thus, using χ2test, the frequency of positive phospho-p65 were increased in MCI (χ2 = 6.039, p = 0.049).

Bottom Line: Recently, TDP-43 was reported to contribute to pathogenesis in amyotrophic lateral sclerosis through its interaction with p65 nuclear factor κB (NF-κB) resulting in abnormal hyperactivation of this signaling pathway in motor neurons.These MCI-p cases exhibited high expression levels of soluble TDP-43, p65, phosphorylated p65 and low expression levels of β-amyloid 40 when compared to AD or NCI cases.From these results, we propose that enhanced NF-κB activation due to TDP-43 and p65 interaction may contribute to neuronal dysfunction in MCI individuals with episodic memory deficits.

View Article: PubMed Central - HTML - PubMed

Affiliation: Research Centre of Institut universitaire en santé mentale de Québec, Québec, QC, Canada. jean-pierre.julien@fmed.ulaval.ca.

ABSTRACT

Introduction: Transactive response DNA binding protein 43 (TDP-43) is detected in pathological inclusions in many cases of Alzheimer's disease (AD) and mild cognitive impairment (MCI), but its pathological role in AD and MCI remains unknown. Recently, TDP-43 was reported to contribute to pathogenesis in amyotrophic lateral sclerosis through its interaction with p65 nuclear factor κB (NF-κB) resulting in abnormal hyperactivation of this signaling pathway in motor neurons. Hence, we investigated the interaction of TDP-43 with p65 in the temporal cortex of subjects with a clinical diagnosis of MCI (n = 12) or AD (n = 12) as well as of age-matched controls with no cognitive impairment (NCI, n = 12).

Results: Immunoprecipitation and immunofluorescence approaches revealed a robust interaction of TDP-43 with p65 in the nucleus of temporal lobe neurons in four individuals with MCI (named MCI-p). These MCI-p cases exhibited high expression levels of soluble TDP-43, p65, phosphorylated p65 and low expression levels of β-amyloid 40 when compared to AD or NCI cases. The analysis of cognitive performance tests showed that MCI-p individuals presented intermediate deficits of global cognition and episodic memory between those of AD cases and of NCI cases and MCI cases with no interaction of TDP-43 with p65.

Conclusions: From these results, we propose that enhanced NF-κB activation due to TDP-43 and p65 interaction may contribute to neuronal dysfunction in MCI individuals with episodic memory deficits. Accordingly, treatment with inhibitors of NF-κB activation may be considered for MCI individuals with episodic memory deficits.

Show MeSH
Related in: MedlinePlus