Altered cleavage and localization of PINK1 to aggresomes in the presence of proteasomal stress.

Following our identification of PTEN-induced putative kinase 1 (PINK1) gene mutations in PARK6-linked Parkinson's disease (PD), we have recently reported that PINK1 protein localizes to Lewy bodies (LBs) in PD brains. We have used a cellular model system of LBs, namely induction of aggresomes, to determine how a mitochondrial protein, such as PINK1, can localize to aggregates. Using specific polyclonal antibodies, we firstly demonstrated that human PINK1 was cleaved and localized to mitochondria.

Hsp27 and Hsp70 administered in combination have a potent protective effect against FALS-associated SOD1-mutant-induced cell death in mammalian neuronal cells.

Amyotrophic lateral sclerosis (ALS) is an adult-onset degenerative disorder characterised by the death of motor neurons in the cortex, brainstem, and spinal cord; resulting in progressive muscle weakness, atrophy, and death from respiratory paralysis, usually within 3-5 years of symptom onset. Approximately 10% of ALS cases are familial (FALS). Mutations in superoxide dismutase-1 (SOD1) cause approximately 20% of FALS cases and there is overwhelming evidence that a toxic gain of function is the cause of the disease.

Cold-sensitive, menthol-insensitive neurons in the murine sympathetic nervous system.

Several mechanisms have been implicated in underlying the perception of cold, most notably the activation of TRPM8 and TRPA1. We have used ratiometric calcium imaging to reveal a population of neurons in the superior cervical ganglion (SCG) of the mouse that respond to cooling but are insensitive to menthol. Furthermore we show that the expression of the mRNA transcripts encoding the recently identified noxious cold-sensitive channel TRPA1 but not TRPM8 are expressed in the SCG.

HSP27 but not HSP70 has a potent protective effect against alpha-synuclein-induced cell death in mammalian neuronal cells.

alpha-Synuclein is a neuronally expressed protein which is mutated in familial Parkinson's disease. We have previously shown that disease-associated mutants of alpha-synuclein cause enhanced neuronal cell death in response to a variety of stimuli, whereas wild-type alpha-synuclein has a protective effect against some stimuli, whilst enhancing the death response to others. We demonstrate, for the first time, that over-expression of the heat shock protein HSP27 has a potent protective anti-apoptotic effect against the damaging effects of wild-type and particularly of mutant alpha-synuclein.

Parkin is recruited into aggresomes in a stress-specific manner: over-expression of parkin reduces aggresome formation but can be dissociated from parkin's effect on neuronal survival.

Parkinson's disease (PD) is characterized by loss of dopamine neurons in the substantia nigra and the presence of cytoplasmic inclusions known as Lewy bodies (LBs). Mutations in parkin cause autosomal recessive juvenile parkinsonism (AR-JP) that is distinct from sporadic PD by the general absence of LBs. Several studies have reported that parkin is present in LBs of sporadic PD but the role of parkin in LB formation is unclear.

Sensory neurons from mice lacking the Brn-3b POU family transcription factor are resistant to death-inducing stimuli both in vitro and in vivo.

The critical role for programmed cell death in the normal development of the nervous system and the abnormal cell death that occurs in human neurodegenerative diseases renders it of vital importance to identify factors that enhance or reduce the levels of cell death in specific neuronal cells in the nervous system. We show that the Brn-3b transcription factor is essential for normal cell death responses in the peripheral nervous system and that in its absence neurons are resistant to a variety of death-inducing stimuli both in vitro and in vivo.

Modulation of cell death by alpha-synuclein is stimulus-dependent in mammalian cells.

alpha-synuclein is a neuronally-expressed protein which is mutated in familial Parkinson's disease. Previous studies have suggested that over-expression of alpha-synuclein can either enhance, reduce or have no effect on the degree of cell death in response to death-inducing stimuli. We resolve this discrepancy by using a well-characterised cell system to demonstrate that wild type alpha-synuclein can enhance cell death in response to ischaemia/reoxygenation or staurosporine treatment whilst protecting against serum removal and dopamine-induced cell death.