PT  - JOURNAL ARTICLE
AU  - Kosuke Kataoka
AU  - Andras Bilkei-Gorzo
AU  - Andreas Zimmer
AU  - Toru Asahi
TI  - Immunohistochemical Characterization of Phosphorylated Ubiquitin in the Mouse Hippocampus
AID  - 10.1101/2020.01.20.912238
DP  - 2020 Jan 01
TA  - bioRxiv
PG  - 2020.01.20.912238
4099  - http://biorxiv.org/content/early/2020/01/21/2020.01.20.912238.short
4100  - http://biorxiv.org/content/early/2020/01/21/2020.01.20.912238.full
AB  - Mitochondrial autophagy (mitophagy) is an essential and evolutionarily conserved process that maintains mitochondrial integrity via the removal of damaged or superfluous mitochondria in eukaryotic cells. Phosphatase and tensin homolog (PTEN)-induced putative kinase 1 (PINK1) and Parkin promote mitophagy and function in a common signaling pathway. PINK1-mediated ubiquitin phosphorylation at Serine 65 (Ser65-pUb) is a key event in the efficient execution of PINK1/Parkin-dependent mitophagy. However, few studies have used immunohistochemistry to analyze Ser65-pUb in the mouse. Here, we examined the immunohistochemical characteristics of Ser65-pUb in the mouse hippocampus. Some hippocampal cells were Ser65-pUb positive, whereas the remaining cells expressed no or low levels of Ser65-pUb. PINK1 deficiency resulted in a decrease in the density of Ser65-pUb-positive cells, consistent with a previous hypothesis based on in vitro research. Interestingly, Ser65-pUb-positive cells were detected in hippocampi lacking PINK1 expression. The CA3 pyramidal cell layer and the dentate gyrus (DG) granule cell layer exhibited significant reductions in the density of Ser65-pUb-positive cells in PINK1-deficient mice. Moreover, Ser65-pUb immunoreactivity colocalized predominantly with neuronal markers. These findings suggest that Ser65-pUb may serve as a biomarker of in situ PINK1 signaling in the mouse hippocampus; however, the results should be interpreted with caution, as PINK1 deficiency downregulated Ser65-pUb only partially.