Induction of autophagy by cystatin C: a mechanism that protects murine primary cortical neurons and neuronal cell lines.
Cystatin C (CysC) expression in the brain is elevated in human patients with epilepsy, in animal models of neurodegenerative conditions, and in response to injury, but whether up-regulated CysC expression is a manifestation of neurodegeneration or a cellular repair response is not understood. This study demonstrates that human CysC is neuroprotective in cultures exposed to cytotoxic challenges, including nutritional-deprivation, colchicine, staurosporine, and oxidative stress. While CysC is a cysteine protease inhibitor, cathepsin B inhibition was not required for the neuroprotective action of CysC. Cells responded to CysC by inducing fully functional autophagy via the mTOR pathway, leading to enhanced proteolytic clearance of autophagy substrates by lysosomes. Neuroprotective effects of CysC were prevented by inhibiting autophagy with beclin 1 siRNA or 3-methyladenine. Our findings show that CysC plays a protective role under conditions of neuronal challenge by inducing autophagy via mTOR inhibition and are consistent with CysC being neuroprotective in neurodegenerative diseases. Thus, modulation of CysC expression has therapeutic implications for stroke, Alzheimer's disease, and other neurodegenerative disorders.
Tizon
Belen
B
Nathan S. Kline Institute, Orangeburg, New York, United States of America.
Sahoo
Susmita
S
Yu
Haung
H
Gauthier
Sebastien
S
Kumar
Asok R
AR
Mohan
Panaiyur
P
Figliola
Matthew
M
Pawlik
Monika
M
Grubb
Anders
A
Uchiyama
Yasuo
Y
Bandyopadhyay
Urmi
U
Cuervo
Ana Maria
AM
Nixon
Ralph A
RA
Levy
Efrat
E
D000225:Adenine / Q000031:analogs & derivatives / Q000378:metabolism; D000818:Animals; D051017:Apoptosis Regulatory Proteins / Q000378:metabolism; D001343:Autophagy; D000071186:Beclin-1; D002460:Cell Line; D003078:Colchicine / Q000494:pharmacology; D055316:Cystatin C / Q000378:metabolism*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D008247:Lysosomes / Q000378:metabolism; D051379:Mice; D019636:Neurodegenerative Diseases / Q000378:metabolism; D009474:Neurons / Q000378:metabolism*; D018384:Oxidative Stress; D051381:Rats; D017207:Rats, Sprague-Dawley; D019311:Staurosporine / Q000494:pharmacology; D058570:TOR Serine-Threonine Kinases / Q000037:antagonists & inhibitors* / Q000378:metabolism; D050257:Tubulin Modulators / Q000494:pharmacology
D051017:Apoptosis Regulatory Proteins; D000071186:Beclin-1; C115010:Becn1 protein, mouse; C512829:Becn1 protein, rat; D055316:Cystatin C; D004791:Enzyme Inhibitors; D050257:Tubulin Modulators; C025946:3-methyladenine; D058570:TOR Serine-Threonine Kinases; D019311:Staurosporine; D000225:Adenine; D003078:Colchicine