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Identification of ubiquilin, a novel presenilin interactor that increases presenilin protein accumulation.

Mah AL, Perry G, Smith MA, Monteiro MJ - J. Cell Biol. (2000)

Bottom Line: However, apart from a role in early development, neither the normal function of the presenilins nor the mechanisms by which mutant proteins cause AD are well understood.Moreover, the anti-ubiquilin antibodies robustly stained neurofibrillary tangles and Lewy bodies in AD and Parkinson's disease affected brains, respectively.Our results indicate that ubiquilin may be an important modulator of presenilin protein accumulation and that ubiquilin protein is associated with neuropathological neurofibrillary tangles and Lewy body inclusions in diseased brain.

View Article: PubMed Central - PubMed

Affiliation: Medical Biotechnology Center, Department of Neurology, University of Maryland Biotechnology Institute, Baltimore, Maryland 21201, USA.

ABSTRACT
Mutations in the highly homologous presenilin genes encoding presenilin-1 and presenilin-2 (PS1 and PS2) are linked to early-onset Alzheimer's disease (AD). However, apart from a role in early development, neither the normal function of the presenilins nor the mechanisms by which mutant proteins cause AD are well understood. We describe here the properties of a novel human interactor of the presenilins named ubiquilin. Yeast two-hybrid (Y2H) interaction, glutathione S-transferase pull-down experiments, and colocalization of the proteins expressed in vivo, together with coimmunoprecipitation and cell fractionation studies, provide compelling evidence that ubiquilin interacts with both PS1 and PS2. Ubiquilin is noteworthy since it contains multiple ubiquitin-related domains typically thought to be involved in targeting proteins for degradation. However, we show that ubiquilin promotes presenilin protein accumulation. Pulse-labeling experiments indicate that ubiquilin facilitates increased presenilin synthesis without substantially changing presenilin protein half-life. Immunohistochemistry of human brain tissue with ubiquilin-specific antibodies revealed prominent staining of neurons. Moreover, the anti-ubiquilin antibodies robustly stained neurofibrillary tangles and Lewy bodies in AD and Parkinson's disease affected brains, respectively. Our results indicate that ubiquilin may be an important modulator of presenilin protein accumulation and that ubiquilin protein is associated with neuropathological neurofibrillary tangles and Lewy body inclusions in diseased brain.

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Anti-ubiquilin staining of human brain tissue reveals strong staining of neurons in human brain and robust staining of NFTs and Lewy bodies of AD and PD, respectively. Sections of human brain were stained with either the preimmune or anti–ubiquilin-B and anti–ubiquilin-C antibodies. (A–D) Consecutive sections of the hippocampus of an AD afflicted brain were stained with either the (A and C) preimmune serum or with their corresponding (B) anti–ubiquilin-B and (D) anti–ubiquilin-C antibodies. (E and F) Examples of strong staining of NFTs (arrows) in hippocampal sections of AD afflicted brains with anti–ubiquilin-C antibodies. (G) Anti–ubiquilin-C antibody staining of a control nonAD human brain showing strong staining of neurons. (H) Cortical human brain section of a DLBD afflicted brain showing strong anti–ubiquilin-C staining of Lewy bodies (arrows). Bars: (A–D and G and H) 40 μm; (E and F) 20 μm.
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Figure 10: Anti-ubiquilin staining of human brain tissue reveals strong staining of neurons in human brain and robust staining of NFTs and Lewy bodies of AD and PD, respectively. Sections of human brain were stained with either the preimmune or anti–ubiquilin-B and anti–ubiquilin-C antibodies. (A–D) Consecutive sections of the hippocampus of an AD afflicted brain were stained with either the (A and C) preimmune serum or with their corresponding (B) anti–ubiquilin-B and (D) anti–ubiquilin-C antibodies. (E and F) Examples of strong staining of NFTs (arrows) in hippocampal sections of AD afflicted brains with anti–ubiquilin-C antibodies. (G) Anti–ubiquilin-C antibody staining of a control nonAD human brain showing strong staining of neurons. (H) Cortical human brain section of a DLBD afflicted brain showing strong anti–ubiquilin-C staining of Lewy bodies (arrows). Bars: (A–D and G and H) 40 μm; (E and F) 20 μm.

Mentions: Since neuropathological lesions in AD and PD have been found to be highly immunoreactive to ubiquitin antibodies, we investigated whether these structures may also contain ubiquilin immunoreactivity. Immunohistochemistry of adult human brain sections was performed with anti–ubiquilin-B and anti–ubiquilin-C antibodies. The former was raised against ubiquilin polypeptides that were devoid of the UB domain, whereas the latter was raised against ubiquilin polypeptides lacking the UBA domain as well (Fig. 2 III, B and C, respectively). Compared with the preimmune sera, which showed no specific staining (Fig. 10A and Fig. C), both antibodies strongly stained neurons with little, if any, staining of glia (Fig. 10B, Fig. D, and Fig. E). In general, the anti–ubiquilin-C antibody stained neurons with greater clarity and intensity. As with cultured cells, anti-ubiquilin staining in neurons was to the nucleus and the cytoplasm. In addition, there is clear evidence for ubiquilin staining within long axonal processes (Fig. 10 D). Interestingly, neurons containing neurofibrillary tangles (NFTs) from AD affected brains seemed to stain more intensely compared with control neurons (Fig. 10 E and F). Moreover, examination of ubiquilin staining in brains afflicted with PD (not shown) and diffuse LB disease revealed robust staining of Lewy bodies (Fig. 10 H).


Identification of ubiquilin, a novel presenilin interactor that increases presenilin protein accumulation.

Mah AL, Perry G, Smith MA, Monteiro MJ - J. Cell Biol. (2000)

Anti-ubiquilin staining of human brain tissue reveals strong staining of neurons in human brain and robust staining of NFTs and Lewy bodies of AD and PD, respectively. Sections of human brain were stained with either the preimmune or anti–ubiquilin-B and anti–ubiquilin-C antibodies. (A–D) Consecutive sections of the hippocampus of an AD afflicted brain were stained with either the (A and C) preimmune serum or with their corresponding (B) anti–ubiquilin-B and (D) anti–ubiquilin-C antibodies. (E and F) Examples of strong staining of NFTs (arrows) in hippocampal sections of AD afflicted brains with anti–ubiquilin-C antibodies. (G) Anti–ubiquilin-C antibody staining of a control nonAD human brain showing strong staining of neurons. (H) Cortical human brain section of a DLBD afflicted brain showing strong anti–ubiquilin-C staining of Lewy bodies (arrows). Bars: (A–D and G and H) 40 μm; (E and F) 20 μm.
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Related In: Results  -  Collection

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Figure 10: Anti-ubiquilin staining of human brain tissue reveals strong staining of neurons in human brain and robust staining of NFTs and Lewy bodies of AD and PD, respectively. Sections of human brain were stained with either the preimmune or anti–ubiquilin-B and anti–ubiquilin-C antibodies. (A–D) Consecutive sections of the hippocampus of an AD afflicted brain were stained with either the (A and C) preimmune serum or with their corresponding (B) anti–ubiquilin-B and (D) anti–ubiquilin-C antibodies. (E and F) Examples of strong staining of NFTs (arrows) in hippocampal sections of AD afflicted brains with anti–ubiquilin-C antibodies. (G) Anti–ubiquilin-C antibody staining of a control nonAD human brain showing strong staining of neurons. (H) Cortical human brain section of a DLBD afflicted brain showing strong anti–ubiquilin-C staining of Lewy bodies (arrows). Bars: (A–D and G and H) 40 μm; (E and F) 20 μm.
Mentions: Since neuropathological lesions in AD and PD have been found to be highly immunoreactive to ubiquitin antibodies, we investigated whether these structures may also contain ubiquilin immunoreactivity. Immunohistochemistry of adult human brain sections was performed with anti–ubiquilin-B and anti–ubiquilin-C antibodies. The former was raised against ubiquilin polypeptides that were devoid of the UB domain, whereas the latter was raised against ubiquilin polypeptides lacking the UBA domain as well (Fig. 2 III, B and C, respectively). Compared with the preimmune sera, which showed no specific staining (Fig. 10A and Fig. C), both antibodies strongly stained neurons with little, if any, staining of glia (Fig. 10B, Fig. D, and Fig. E). In general, the anti–ubiquilin-C antibody stained neurons with greater clarity and intensity. As with cultured cells, anti-ubiquilin staining in neurons was to the nucleus and the cytoplasm. In addition, there is clear evidence for ubiquilin staining within long axonal processes (Fig. 10 D). Interestingly, neurons containing neurofibrillary tangles (NFTs) from AD affected brains seemed to stain more intensely compared with control neurons (Fig. 10 E and F). Moreover, examination of ubiquilin staining in brains afflicted with PD (not shown) and diffuse LB disease revealed robust staining of Lewy bodies (Fig. 10 H).

Bottom Line: However, apart from a role in early development, neither the normal function of the presenilins nor the mechanisms by which mutant proteins cause AD are well understood.Moreover, the anti-ubiquilin antibodies robustly stained neurofibrillary tangles and Lewy bodies in AD and Parkinson's disease affected brains, respectively.Our results indicate that ubiquilin may be an important modulator of presenilin protein accumulation and that ubiquilin protein is associated with neuropathological neurofibrillary tangles and Lewy body inclusions in diseased brain.

View Article: PubMed Central - PubMed

Affiliation: Medical Biotechnology Center, Department of Neurology, University of Maryland Biotechnology Institute, Baltimore, Maryland 21201, USA.

ABSTRACT
Mutations in the highly homologous presenilin genes encoding presenilin-1 and presenilin-2 (PS1 and PS2) are linked to early-onset Alzheimer's disease (AD). However, apart from a role in early development, neither the normal function of the presenilins nor the mechanisms by which mutant proteins cause AD are well understood. We describe here the properties of a novel human interactor of the presenilins named ubiquilin. Yeast two-hybrid (Y2H) interaction, glutathione S-transferase pull-down experiments, and colocalization of the proteins expressed in vivo, together with coimmunoprecipitation and cell fractionation studies, provide compelling evidence that ubiquilin interacts with both PS1 and PS2. Ubiquilin is noteworthy since it contains multiple ubiquitin-related domains typically thought to be involved in targeting proteins for degradation. However, we show that ubiquilin promotes presenilin protein accumulation. Pulse-labeling experiments indicate that ubiquilin facilitates increased presenilin synthesis without substantially changing presenilin protein half-life. Immunohistochemistry of human brain tissue with ubiquilin-specific antibodies revealed prominent staining of neurons. Moreover, the anti-ubiquilin antibodies robustly stained neurofibrillary tangles and Lewy bodies in AD and Parkinson's disease affected brains, respectively. Our results indicate that ubiquilin may be an important modulator of presenilin protein accumulation and that ubiquilin protein is associated with neuropathological neurofibrillary tangles and Lewy body inclusions in diseased brain.

Show MeSH
Related in: MedlinePlus