Inhibition of calpain increases LIS1 expression and partially rescues in vivo phenotypes in a mouse model of lissencephaly

Abstract

Lissencephaly is a devastating neurological disorder due to defective neuronal migration. LIS1 (or PAFAH1B1) was identified as the gene mutated in lissencephaly patients, and was found to regulate cytoplasmic dynein function and localization. Here, we show that more than half of LIS1 is degraded via calpain-dependent proteolysis, and that inhibition or knockdown of calpains protects LIS1 from proteolysis, resulting in the augmentation of LIS1 levels in Lis1+/− mouse embryonic fibroblast (MEF) cells, which leads to rescue of the aberrant distribution of cytoplasmic dynein, mitochondria and β-COP positive vesicles. We also show that calpain inhibitors improve neuronal migration of Lis1+/− cerebellar granular neurons. Intra-peritoneal injection of ALLN to pregnant Lis1+/− dams rescued apoptotic neuronal cell death and neuronal migration defects in Lis1+/− offspring. Furthermore, in utero knockdown of calpain by shRNA rescued defective cortical layering in Lis1+/− mice. Thus, the inhibition of calpain is a potential therapeutic intervention for lissencephaly.

Vital Role of the Calpain-Calpastatin System for Placental-Integrity-Dependent Embryonic Survival

“…The calpain-calpastatin system has been shown to participate in a number of pathological conditions, including hypoxia, ischemia, spinal cord injury, Alzheimer's disease, muscular dystrophy, cataract, and lissencephaly (26,36,39). This is reflected in the finding that calpastatin deficiency enhances amyloidosis, inflammation, and neuronal atrophy in a mouse model of Alzheimer's disease (M. Higuchi and T. C. Saido, unpublished data).…”

The essential role of LIS1, NDEL1 and Aurora-A in polarity formation and microtubule organization during neurogensis

“…We recently demonstrated that inhibition or knockdown of calpain protects LIS1 from proteolysis resulting in the augmen tation of LIS1 levels in Lis1 +/-mouse embryonic fibroblast (MEF) cells, which leads to rescue of the aberrant distribution of cytoplasmic dynein and intracellular components including mitochondria and β-COP positive vesicles. 18 We also showed that presence of calpain inhibitors improves neuronal migration of Lis1 +/-cerebellar granular neurons. 18 This study demonstrates that stabilization of proteins in disorders caused by haploinsufficiency is a potential therapeutic strategy and provides a proof-of-principle for this notion.…”

Rab6a releases LIS1 from a dynein idling complex and activates dynein for retrograde movement

“…Although mNUDC is required for anterograde transport of a dynactin-containing complex, the dynein complex and the dynactin complex were separately transported to the plus end of MTs 9 . Interestingly, half of the LIS1 is degraded through calpain-dependent proteolysis at the plus end of MTs, and that inhibition or knockdown of calpains protects LIS1 from proteolysis, which leads to the rescue of the phenotypes in Lis1 þ / À mice 14 . Despite numerous studies for the regulation of motor proteins, the mechanism of LIS1 release from idling dynein at the plus end of MTs remains poorly understood.…”