Climacostol reduces tumour progression in a mouse model of melanoma via the p53-dependent intrinsic apoptotic programme.

Climacostol, a compound produced by the ciliated protozoan Climacostomum virens, displayed cytotoxic properties in vitro. This study demonstrates that it has anti-tumour potential. Climacostol caused a reduction of viability/proliferation of B16-F10 mouse melanoma cells, a rapidly occurring DNA damage, and induced the intrinsic apoptotic pathway characterised by the dissipation of the mitochondrial membrane potential, the translocation of Bax to the mitochondria, the release of Cytochrome c from the mitochondria, and the activation of Caspase 9-dependent cleavage of Caspase 3. The apoptotic mechanism of climacostol was found to rely on the up-regulation of p53 and its targets Noxa and Puma. In vivo analysis of B16-F10 allografts revealed a persistent inhibition of tumour growth rate when melanomas were treated with intra-tumoural injections of climacostol. In addition, it significantly improved the survival of transplanted mice, decreased tumour weight, induced a remarkable reduction of viable cells inside the tumour, activated apoptosis and up-regulated the p53 signalling network. Importantly, climacostol toxicity was more selective against tumour than non-tumour cells. The anti-tumour properties of climacostol and the molecular events associated with its action indicate that it is a powerful agent that may be considered for the design of pro-apoptotic drugs for melanoma therapy.

Neuronal-specific roles of the survival motor neuron protein: evidence from survival motor neuron expression patterns in the developing human central nervous system.

Despite recent data on the cellular function of the survival motor neuron (SMN) gene, the spinal muscular atrophy (SMA) disease gene, the role of the SMN protein in motor neurons and hence in the pathogenesis of SMA is still unclear. The spatial and temporal expression of SMN in neurons, particularly during development, could help in verifying the hypotheses on the SMN protein functions so far proposed. We have therefore investigated the expression and subcellular localization of the SMN protein in the human central nervous system (CNS) during ontogenesis with immunocytochemical, confocal immunofluorescence, and Western blot experiments using a panel of anti-SMN antibodies recognizing the full-length SMN protein. The experiments not only revealed the early SMN expression in all neurons, but also demonstrated the progressive shift in SMN subcellular localization from mainly nuclear to cytoplasmic and then to axons during CNS maturation. This finding was present in selected neuronal cell populations and it was particularly conspicuous in motor neurons. Our data support the idea of a specific role for SMN in axons, which becomes predominant in the ontogenetic period encompassing axonogenesis and axonal sprouting. In addition, the asymmetric SMN staining demonstrated in the germinative neuroepithelium suggests a possible role for SMN in neuronal migration and/or differentiation.

Electroencephalographic recordings of focal seizures in patients affected by periventricular nodular heterotopia: role of the heterotopic nodules in the genesis of epileptic discharges.

Patients affected by periventricular nodular heterotopia are frequently characterized by focal drug-resistant epilepsy. To investigate the role of periventricular nodules in the genesis of seizures, we analyzed the electroencephalographic (EEG) features of focal seizures recorded by means of video-EEG in 10 patients affected by different types of periventricular nodular heterotopia and followed for prolonged periods of time at the epilepsy center of our institute. The ictal EEG recordings with surface electrodes revealed common features in all patients: all seizures originated from the brain regions where the periventricular nodular heterotopia were located; EEG patterns recorded on the leads exploring the periventricular nodular heterotopia were very similar both at the onset and immediately after the seizure's end in all patients. Our data suggest that seizures are generated by abnormal anatomic circuitries, including the heterotopic nodules and adjacent cortical areas. The major role of heterotopic neurons in the genesis and propagation of epileptic discharges must be taken into account when planning surgery for epilepsy in patients with periventricular nodular heterotopia.

Abnormal lysosomal and ubiquitin-proteasome pathways in 19p13.3 distal myopathy.

We describe a second large Italian kindred with autosomal dominant vacuolar myopathy characterized by variable severity, adult-onset weakness of distal limb muscles, and no cardiac involvement. At least 19 individuals over four generations are affected. Histopathological and immunochemical features of the vacuoles, present in many fibers, indicate protein degradation abnormalities with dysregulation of the lysosomal pathway and activation of the ubiquitin-proteasomal pathway. Linkage analysis localized the defect to the 19p13.3 locus in a region with no known genes. We speculate that the primary defect may be an abnormality in the lysosomal degradation pathway or related components.

The genesis of epileptogenic cerebral heterotopia: clues from experimental models.

The pre-natal administration of methylazoxymethanol acetate (MAM) in rats is able to induce cerebral heterotopia that share striking similarities with those observed in human periventricular nodular heterotopia, a cerebral dysgenesis frequently associated with drug-resistant focal seizures. In the present study, we investigated the mode of neurogenesis in cerebral heterotopia of MAM-treated rats, by analyzing post-natal cytoarchitectural features and time of neurogenesis using bromodeoxyuridine immunocytochemistry. The cytoarchitectural analysis demonstrated the existence, in the early post-natal period, of white matter cellular bands in close anatomical relationship with the heterotopia, which most likely serve as a reservoir of young, migrating neurons for the newly forming heterotopia. The birth dating analysis demonstrated that the period of generation of neurons within the heterotopia and adjacent white matter bands, was extended in comparison to corticogenesis in normal rat brains. In addition, it demonstrated that the heterotopia were formed through a rather precise outside-in (for cortical and periventricular heterotopia) and dorso-ventral (for intra-hippocampal heterotopia) neurogenetic pattern. We hypothesize that the MAM-induced ablation of an early wave of cortical neurons is sufficient to alter per se the migration and differentiation of subsequently generated neurons, which in turn set the base for the formation of the different types of heterotopia. On this basis, we suggest a neurogenetic scheme for MAM-induced heterotopia that can also explain the origin and intrinsic epileptogenicity of periventricular nodular heterotopia in humans.

Constitutive knockout of Surf1 is associated with high embryonic lethality, mitochondrial disease and cytochrome c oxidase deficiency in mice.

We report here the creation of a constitutive knockout mouse for SURF1, a gene encoding one of the assembly proteins involved in the formation of cytochrome c oxidase (COX). Loss-of-function mutations of SURF1 cause Leigh syndrome associated with an isolated and generalized COX deficiency in humans. The murine phenotype is characterized by the following hallmarks: (1) high post-implantation embryonic lethality, affecting approximately 90% of the Surf1(-/-) individuals; (2) early-onset mortality of post-natal individuals; (3) highly significant deficit in muscle strength and motor performance; (4) profound and isolated defect of COX activity in skeletal muscle and liver, and, to a lesser extent, heart and brain; (5) morphological abnormalities of skeletal muscle, characterized by reduced histochemical reaction to COX and mitochondrial proliferation; (6) no obvious abnormalities in brain morphology, reflecting the virtual absence of overt neurological symptoms. These results indicate a function for murine Surf1 protein (Surf1p) specifically related to COX and recapitulate, at least in part, the human phenotype. This is the first mammalian model for a nuclear disease gene of a human mitochondrial disorder. Our model constitutes a useful tool to investigate the function of Surf1p, help understand the pathogenesis of Surf1p deficiency in vivo, and evaluate the efficacy of treatment.