Page 48 - ebook
P. 48
[A. Biochemistry/Molecular Biology] A-24
Circulating Proteasome Activity in Blood Plasma as a Novel
Biomarker in Mild Cognitive Impairment with Chronic
Tinnitus
Yejin Yun¹,², Sumin Kim¹,², Dawon Jeong¹,², Min Jae Lee¹,²*
¹Department of Biochemistry and Molecular Biology, Seoul National University College of Medicine, Seoul 03080,
Korea, ²Department of Biomedical Sciences, Seoul National University College of Medicine, Seoul 03080, Korea
The proteasome is the major proteolytic enzyme complex involved in the maintenance of protein quality control in
the cell. Although the existence of proteasomes in human blood, termed circulating proteasomes (c-proteasomes),
has been reported previously, their origin and pathophysiological functions remain largely unknown. Over the course
of biochemically characterizing c-proteasomes, we observed that the catalytic activity of c-proteasomes was
significantly reduced in multiple lines of Alzheimer’s disease model mice. Given that a relatively high frequency of
mild cognitive impairment (MCI) is accompanied by chronic tinnitus in aged patients, we examined whether c-
proteasome activity in human plasma was associated with cognitive function in patients with chronic tinnitus (N =
55). The activity of c-proteasome was significantly lower in patients with chronic tinnitus and MCI (p = 0.042),
whereas activities of other plasma enzymes showed little correlation with c-proteasome activity. In addition, c-
proteasome activity was negatively associated with the level of plasma beta-amyloids and was directly dependent
on its own concentration in the plasma of patients with chronic tinnitus.
