About this Research Topic
Human cystatins have been studied thoroughly; from structure to pathology. They are found in various types of cytoplasmic vesicles, including secretory vesicles (cystatin C), in lysosomes, spread in the cytoplasm and the nucleus (stefin B, i.e., cystatin B). They are protease inhibitors of multiple proteins, including lysosomal cysteine cathepsins. However, it was demonstrated that they exert alternative and additional functions, among them bridging cytoskeletal proteins (Di Giamo et al., 2002), fighting oxidative stress (Lehtinen et al, 2009), augmenting autophagy (Tizon et al., 2007), and regulating transcription by binding to histones (Ceru et al., 2010). Two cystatins have pathogenic roles in the central nervous system. Cystatin C is an amyloidogenic protein causing hereditary cystatin C amyloid angiopathy (HCCAA), and stefin B (cystatin B, CSTB gene) mutations cause progressive myoclonus epilepsy of type 1 (EPM1). Cystatins are prone to form domain-swapped dimers and higher oligomers. As model animal studies show that while enhanced inhibition of cathepsins is beneficial in certain neurodegenerative disorders, absence of these inhibitors proves beneficial in other (Zerovnik 2009). Under stress conditions such as status epilepticus, hypoxia and epileptic seizures, cystatins are overexpressed, suggesting their neuroprotective role. However, the exact in vivo physiological function(s) of cystatins and their pathogenic roles are not completely understood and the purpose of this Research Topic is to delineate major directions for further study.
Table of Topics:
1. Structural characteristics of cystatins and stefins
2. Amyloid formation in vitro and in ex vivo
3. Cystatins in neurodegenerative symptomatology
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