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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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TDP-43 colocalizes with p65 in the nucleus of neurons of the temporal cortex of individuals with MCI showing the interaction of TDP-43 with p65 in coimmunoprecipitation experiments (Figure1B, C; MCI-p). a, b A section from the temporal cortex of MCI-p (Subject 15) were incubated with anti-p65 and anti-TDP-43 (a) or anti-NeuN (b) antibodies and subsequently with corresponding Alexa 488 and 633 antibodies (Molecular Probes), and imaged by confocal laser microscopy. The nuclei were counterstained with Dapi. Autofluorescence was detected using 575–630 nm bandpass emission filter. Arrows indicate colocalization of Dapi, p65 and TDP-43 (a) or NeuN (b). Scale bars, 50 μm.
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Figure 2: TDP-43 colocalizes with p65 in the nucleus of neurons of the temporal cortex of individuals with MCI showing the interaction of TDP-43 with p65 in coimmunoprecipitation experiments (Figure1B, C; MCI-p). a, b A section from the temporal cortex of MCI-p (Subject 15) were incubated with anti-p65 and anti-TDP-43 (a) or anti-NeuN (b) antibodies and subsequently with corresponding Alexa 488 and 633 antibodies (Molecular Probes), and imaged by confocal laser microscopy. The nuclei were counterstained with Dapi. Autofluorescence was detected using 575–630 nm bandpass emission filter. Arrows indicate colocalization of Dapi, p65 and TDP-43 (a) or NeuN (b). Scale bars, 50 μm.

Mentions: To examine the subcellular distribution of interaction of TDP-43 with p65, double immunofluorescence staining using anti-TDP-43 and anti-p65 antibodies was performed on paraffin-embedded sections of the temporal cortex from the same series of samples (Figures 2a, 3 and Additional file 1: Figure S1). As expected, TDP-43 was normally found in the nucleus of neuronal cells in the temporal cortex of subjects with NCI, MCI and AD. The nuclear colocalization of p65 with TDP-43 in neurons was observed predominantly in MCI individuals (Figures 2a, 3a and Additional file 1: Figure S1a, arrows) who showed interaction of TDP-43 with p65 as determined by coimmunoprecipitation assays, especially Subjects 8, 15, 17 and 23 that we defined as MCI-p. To identify neuronal cells expressing p65, immunofluorescence staining using anti-p65 plus anti-NeuN antibodies as a neuronal marker was performed for subjects with MCI-p (Figure 2b). Strong signals of p65 were found in the nucleus of many neurons in the subjects with MCI-p (Figure 2b, arrows). On the contrary, subjects with NCI and AD showing the interaction of TDP-43 with p65 in coimmunoprecipitation experiments (Figure 1b,c; Subjects 7, 14, 21 and 29; NCI-p and Subject 2; AD-p) and MCI without the interaction of TDP-43 with p65 (Figure 1b,c; MCI-n) presented only few cells expressing p65 in the nucleus (Figures 3b-d, Additional file 1: Figure S1c). Among the subjects with MCI-p, the frequencies of colocalization of TDP-43 with p65 in the nuclear TDP-43 positive cells were higher in Subjects 8 and 15 (Figure 3a; 45.6%) compared to Subjects 17 and 23 (Additional file 1: Figure S1a; 12.5%). On the contrary, only few TDP-43 positive cells showed p65 signals in the subjects identified as MCI-n (Figure 3b). Note the absence of TDP-43 and/or p65 aggregates in Figures 2 and 3. The cytosolic signals detected are due to autofluorescence. These results corroborated band intensities detected after coimmunoprecipitation of TDP-43 with p65 (Figure 1b,c). Although 1 individual with AD-p (Subject 2) and 4 individuals with NCI-p (Subjects 7, 14, 21 and 29) showed weak interaction of TDP-43 with p65 in coimmunoprecipitation experiments (Figure 1b,c), the frequencies of colocalization of TDP-43 with p65 in TDP-43 cells of these subjects was lower (5.6% and 8.1%, respectively) than MCI-p (mean of Subjects 8, 15, 17 and 23 is 29.0%). In AD without the interaction of TDP-43 with p65 in coimmunoprecipitation experiments (Figure 1b,c; AD-n), only few TDP-43 positive cells showed p65 signals (Additional file 1: Figure S1b). This result suggests that the interaction of TDP-43 with p65 in the neurons of temporal lobe was stronger in some subjects with MCI (Subjects 8, 15, 17 and 23) compared to AD and NCI. In previous work using same series of samples [21], TDP-43 immunofluorescence in the cytoplasm of neuron-like cells was detected in 6 individuals with AD, 4 individuals with MCI and one individual with NCI, which is not a typical pathology as FTLD-TDP [2,40,41].


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)

TDP-43 colocalizes with p65 in the nucleus of neurons of the temporal cortex of individuals with MCI showing the interaction of TDP-43 with p65 in coimmunoprecipitation experiments (Figure1B, C; MCI-p). a, b A section from the temporal cortex of MCI-p (Subject 15) were incubated with anti-p65 and anti-TDP-43 (a) or anti-NeuN (b) antibodies and subsequently with corresponding Alexa 488 and 633 antibodies (Molecular Probes), and imaged by confocal laser microscopy. The nuclei were counterstained with Dapi. Autofluorescence was detected using 575–630 nm bandpass emission filter. Arrows indicate colocalization of Dapi, p65 and TDP-43 (a) or NeuN (b). Scale bars, 50 μm.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Figure 2: TDP-43 colocalizes with p65 in the nucleus of neurons of the temporal cortex of individuals with MCI showing the interaction of TDP-43 with p65 in coimmunoprecipitation experiments (Figure1B, C; MCI-p). a, b A section from the temporal cortex of MCI-p (Subject 15) were incubated with anti-p65 and anti-TDP-43 (a) or anti-NeuN (b) antibodies and subsequently with corresponding Alexa 488 and 633 antibodies (Molecular Probes), and imaged by confocal laser microscopy. The nuclei were counterstained with Dapi. Autofluorescence was detected using 575–630 nm bandpass emission filter. Arrows indicate colocalization of Dapi, p65 and TDP-43 (a) or NeuN (b). Scale bars, 50 μm.
Mentions: To examine the subcellular distribution of interaction of TDP-43 with p65, double immunofluorescence staining using anti-TDP-43 and anti-p65 antibodies was performed on paraffin-embedded sections of the temporal cortex from the same series of samples (Figures 2a, 3 and Additional file 1: Figure S1). As expected, TDP-43 was normally found in the nucleus of neuronal cells in the temporal cortex of subjects with NCI, MCI and AD. The nuclear colocalization of p65 with TDP-43 in neurons was observed predominantly in MCI individuals (Figures 2a, 3a and Additional file 1: Figure S1a, arrows) who showed interaction of TDP-43 with p65 as determined by coimmunoprecipitation assays, especially Subjects 8, 15, 17 and 23 that we defined as MCI-p. To identify neuronal cells expressing p65, immunofluorescence staining using anti-p65 plus anti-NeuN antibodies as a neuronal marker was performed for subjects with MCI-p (Figure 2b). Strong signals of p65 were found in the nucleus of many neurons in the subjects with MCI-p (Figure 2b, arrows). On the contrary, subjects with NCI and AD showing the interaction of TDP-43 with p65 in coimmunoprecipitation experiments (Figure 1b,c; Subjects 7, 14, 21 and 29; NCI-p and Subject 2; AD-p) and MCI without the interaction of TDP-43 with p65 (Figure 1b,c; MCI-n) presented only few cells expressing p65 in the nucleus (Figures 3b-d, Additional file 1: Figure S1c). Among the subjects with MCI-p, the frequencies of colocalization of TDP-43 with p65 in the nuclear TDP-43 positive cells were higher in Subjects 8 and 15 (Figure 3a; 45.6%) compared to Subjects 17 and 23 (Additional file 1: Figure S1a; 12.5%). On the contrary, only few TDP-43 positive cells showed p65 signals in the subjects identified as MCI-n (Figure 3b). Note the absence of TDP-43 and/or p65 aggregates in Figures 2 and 3. The cytosolic signals detected are due to autofluorescence. These results corroborated band intensities detected after coimmunoprecipitation of TDP-43 with p65 (Figure 1b,c). Although 1 individual with AD-p (Subject 2) and 4 individuals with NCI-p (Subjects 7, 14, 21 and 29) showed weak interaction of TDP-43 with p65 in coimmunoprecipitation experiments (Figure 1b,c), the frequencies of colocalization of TDP-43 with p65 in TDP-43 cells of these subjects was lower (5.6% and 8.1%, respectively) than MCI-p (mean of Subjects 8, 15, 17 and 23 is 29.0%). In AD without the interaction of TDP-43 with p65 in coimmunoprecipitation experiments (Figure 1b,c; AD-n), only few TDP-43 positive cells showed p65 signals (Additional file 1: Figure S1b). This result suggests that the interaction of TDP-43 with p65 in the neurons of temporal lobe was stronger in some subjects with MCI (Subjects 8, 15, 17 and 23) compared to AD and NCI. In previous work using same series of samples [21], TDP-43 immunofluorescence in the cytoplasm of neuron-like cells was detected in 6 individuals with AD, 4 individuals with MCI and one individual with NCI, which is not a typical pathology as FTLD-TDP [2,40,41].

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