Details

Autor(en) / Beteiligte

• Rentsendorj, Altan
• Raedschelders, Koen
• Vaibhav, Vineet
• Porritt, Rebecca A
• Fuchs, Dieu‐Trang
• Sheyn, Julia
• Shi, Haoshen
• Dagvadorj, Jargalsaikhan
• Koronyo, Yosef
• Arditi, Moshe
• Black, Keith L
• Van Eyk, Jennifer E
• Koronyo‐Hamaoui, Maya

Titel

Proteomics profiling reveals Spp1 deficiency to downregulate UCHL1 in macrophages and to associate with lysosome‐mitochondria mediated apoptotic pathways

Ist Teil von

• Alzheimer's & dementia, 2021-12, Vol.17 (S3), p.e055297-n/a

Ort / Verlag

United States

Erscheinungsjahr

2021

Link zum Volltext

Quelle

Wiley Online Library All Journals

Beschreibungen/Notizen

• Background Osteopontin (OPN; Spp1) is an immunomodulatory cytokine highly expressed by bone marrow‐derived macrophages (BMMΦ) known to regulate immune cell responses to brain injury. We have previously found that glatiramer acetate (GA) upregulates Spp1 expression, promoting an anti‐inflammatory and highly phagocytic phenotype in macrophages. Knockout of OPN (Spp1‐/‐) in BMMΦ impairs Alzheimer’s disease (AD)‐related amyloid‐β (Aβ40 and Aβ42) phagocytosis and hinders the neuroprotective phenotype. Method Here, we applied quantitative proteomics profiling and targeted immunohistochemistry (IHC) to explore the effects of Spp1 deficiency and GA modulation on protein networks of BMMΦ in vitro and in brains of AD transgenic (ADtg) mice. Result Mass spectrometry analysis detected over 630 differentially expressed proteins in Spp1‐/‐ BMMΦ cell culture lysates. Approximately 170 proteins showed significantly (p<0.05) altered expression (>1.2‐fold). In Spp1‐/‐ cells, proteins were downregulated by a factor of 0.1‐1.23, whereas the same proteins were upregulated in GA‐stimulated cells by a factor of 0.1 to 1.42, relative to WT cells. Numerous ubiquitin proteasome system (UPS) related proteins were downregulated in Spp1‐/‐ macrophages. Of UPS proteins, ubiquitin carboxyterminal hydrolase L1 (UCHL1) was most downregulated in Spp1‐/‐ cells and upregulated by GA stimulation. We confirmed these findings by IHC and Western blot analysis in BMMΦ cells. Additionally, UCHL1 colocalized within Spp1‐expressing Iba1+CD45high infiltrating myelomonocytes in vivo; these cells migrated and concentrated around Aβ plaques in cortices ADtg mice. We revealed that Spp1 directly interacts with UCHL1 as validated by co‐immunoprecipitation. Further, substantial reductions in expression of proteins involved in translation in Spp1‐/‐ BMMΦ indicate that Spp1 may regulate translation processes. Importantly, lysosomal, mitochondrial and apoptosis pathway‐associated proteins were upregulated in Spp1‐deficient macrophages, including Lysozyme C‐2, ATP‐synthase subunits, Cathepsins and Cytochrome C and B subunits. Enhanced expression of lysosomal proteins in SPP1‐/‐ BMMΦ cells indicates increased autophagy. Conclusion Spp1 deficiency in macrophages downregulates UCHL1 and associates with lysosome‐mitochondria mediated apoptosis pathway. This study reveals that UCHL1 is expressed by macrophages in vitro as well as in vivo in cerebral infiltrating immune cells in ADtg mice, thereby identifying novel UPS and lysosome‐mitochondrial related therapeutic targets for AD.