Journal Article

Sushi repeat-containing protein 1: a novel disease-associated molecule in cerebral amyloid angiopathy

Kakita, Akiyoshi, Ando, Yukio, Inoue, Yasuteru, Matsumoto, Sayaka, Mizukami, Mayumi, Ueda, Mitsuharu, Masuda, Teruaki, Nagatoshi, Akihito, Misumi, Yohei, Yamashita, Taro, Takahashi, Hitoshi, Kosaka, Takayuki, Takeshima, Akari, Nomura, Toshiya, Tasaki, Masayoshi

2017

Overview

Sporadic cerebral amyloid angiopathy (CAA) is characterized by cerebrovascular amyloid beta (Aβ) deposits and causes cerebral hemorrhage and dementia. The exact molecules that co-accumulate with cerebrovascular Aβ deposits are still not fully known. In our study here, we performed proteomic analyses with microdissected leptomeningeal arteries and cerebral neocortical arterioles from 8 cases with severe CAA, 12 cases with mild CAA, and 10 control cases without CAA, and we determined the levels of highly expressed proteins in cerebral blood vessels in CAA. We focused on sushi repeat-containing protein 1 (SRPX1), which is specifically expressed in CAA-affected cerebral blood vessels. Because SRPX1, which is known as a tumor suppressor gene, reportedly induced apoptosis in tumor cells, we hypothesized that SRPX1 may play an important role in Aβ-induced apoptosis in CAA. Immunohistochemical studies revealed that SRPX1 co-accumulated with Aβ deposits in cerebral blood vessels of all autopsied cases with severe CAA. In contrast, no SRPX1 co-accumulated with Aβ deposits in senile plaques. Furthermore, we demonstrated that both Aβ40 and Aβ42 bound to SRPX1 in vitro and enhanced SRPX1 expression in primary cultures of cerebrovascular smooth muscle cells. SRPX1 enhanced caspase activity induced by Aβ40. Knockdown of SRPX1, in contrast, reduced the formation of Aβ40 accumulations and the activity of caspase in cultured cerebrovascular smooth muscle cells. SRPX1 may thus be a novel molecule that is up-regulated in cerebrovascular Aβ deposits and that may increase Aβ-induced cerebrovascular degeneration in CAA.

• Publisher: Springer Berlin Heidelberg,Springer,Springer Nature B.V
• Subject: Aged / Aged, 80 and over / Amyloid beta-Peptides - metabolism / Analysis / Animals / Apolipoproteins E - genetics / Apoptosis / Arteries / Arterioles / Blood vessels / Brain / Brain - metabolism / Brain - pathology / Caspase / Cells, Cultured / Cerebral amyloid angiopathy / Cerebral Amyloid Angiopathy - genetics / Cerebral Amyloid Angiopathy - metabolism / Cerebral Amyloid Angiopathy - pathology / Cerebrovascular system / Circulatory system / Degeneration / Dementia disorders / Deposits / Female / Hemorrhage / Humans / Male / Medicine / Medicine & Public Health / Membrane Proteins - genetics / Membrane Proteins - metabolism / Meninges / Mice, Inbred C57BL / Middle Aged / Myocytes, Smooth Muscle - metabolism / Neocortex / Neurofibrillary Tangles - metabolism / Neurofibrillary Tangles - pathology / Neurosciences / Original Paper / Pathology / Peptide Fragments - metabolism / Protein Binding / Proteins / Proteome / RNA, Small Interfering / Senile plaques / Smooth muscle / Tumor cells / Tumor suppressor genes / β-Amyloid