Mitochondrial dysfunction is implicated in the pathophysiology of Parkinsons disease (PD), a common age-associated neurodegenerative disease characterized by intraneuronal inclusions (Lewy bodies) and progressive degeneration of the nigrostriatal dopamine (DA) system. It has recently been demonstrated that midbrain DA neurons of PD patients and elderly humans contain high levels of somatic mtDNA mutations, which may impair respiratory chain function. However, clinical studies have not established whether the respiratory chain deficiency is a primary abnormality leading to inclusion formation and DA neuron death, or whether generalized metabolic abnormalities within the degenerating DA neurons cause secondary damage to mitochondria. We have used a reverse genetic approach to investigate this question and created conditional knockout mice (termed MitoPark mice), with disruption of the gene for mitochondrial transcription factor A (Tfam) in DA neurons. The knockout mice have reduced mtDNA expression and respiratory chain deficiency in midbrain DA neurons, which, in turn, leads to a parkinsonism phenotype with adult onset of slowly progressive impairment of motor function accompanied by formation of intraneuronal inclusions and dopamine nerve cell death. Confocal and electron microscopy show that the inclusions contain both mitochondrial protein and membrane components. These experiments demonstrate that respiratory chain dysfunction in DA neurons may be of pathophysiological importance in PD.inclusion ͉ mitochondria ͉ mtDNA ͉ neurodegeneration ͉ Parkinson

Summary Although many distinct mutations in a variety of genes are known to cause Amyotrophic Lateral Sclerosis (ALS), it remains poorly understood how they selectively impact motor neuron biology and whether they converge on common pathways to cause neuronal degeneration. Here, we have combined reprogramming and stem cell differentiation approaches with genome engineering and RNA sequencing to define the transcriptional and functional changes that are induced in human motor neurons by mutant SOD1. Mutant SOD1 protein induced a transcriptional signature indicative of increased oxidative stress, reduced mitochondrial function, altered sub-cellular transport as well as activation of the ER stress and unfolded protein response pathways. Functional studies demonstrated that these pathways were perturbed in a manner dependent on the SOD1 mutation. Finally, interrogation of stem cell-derived motor neurons produced from ALS patients harboring a repeat expansion in C9orf72 indicates at least a subset of these changes are more broadly conserved in ALS.

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Inflammation and activation of immune cells are key mechanisms in the development of atherosclerosis. Previous data indicate important roles for monocytes and T-lymphocytes in lesions. However, recent data suggest that neutrophils also may be of importance in atherogenesis. Here, we use apolipoprotein E (ApoE)-deficient mice with fluorescent neutrophils and monocytes (ApoE ؊/؊ /Lys EGFP/EGFP mice) to specifically study neutrophil presence and recruitment in atherosclerotic lesions. We show by flow cytometry and confocal microscopy that neutrophils make up for 1.8% of CD45 ؉ leukocytes in the aortic wall of ApoE ؊/؊ /Lys EGFP/EGFP mice and that their contribution relative to monocyte/macrophages within lesions is approximately 1:3. However, neutrophils accumulate at sites of monocyte high density, preferentially in shoulder regions of lesions, and may even outnumber monocyte/macrophages in these areas. Furthermore, intravital microscopy established that a majority of leukocytes interacting with endothelium on lesion shoulders are neutrophils, suggesting a significant recruitment of these cells to plaque. These data demonstrate neutrophilic granulocytes as a major cellular component of atherosclerotic lesions in ApoE ؊/؊ mice and call for further study on the roles of these cells in atherogenesis. Recruitment of immune cells to the arterial intima is central to atherogenesis. Current dogma emphasizes the role of macrophages and T-lymphocytes in promoting plaque development and destabilization.1,2 However, the most abundant white blood cell in the circulation, the neutrophilic granulocyte, has until recently rarely been associated with the development of atherosclerosis. Nonetheless, proteins typically secreted by neutrophils are abundant in lesions, [3][4][5][6][7] and systemic neutrophil counts appear to correlate closely with severity of atherosclerosis in humans.8 Similar observations were also recently made in the murine system in which increased peripheral neutrophil count was associated with enhanced plaque size, whereas the opposite was true when neutrophils were depleted from the circulation. There are also data that indicate presence of neutrophils in lesions of low-density lipoprotein (LDL) receptor-deficient mice.5 Despite these findings, data on potential roles of neutrophils in atherogenesis are rare in the literature.We recently crossed apolipoprotein E-deficient ApoE mice, which allow for sensitive detection of neutrophils in atherosclerotic plaques. 11 Here, we study the presence and spatial distribution of neutrophils in atherosclerotic arteries of these mice. We demonstrate that neutrophils are present in substantial numbers in aortic plaque. Moreover, their contribution is higher in shoulder regions of plaque, which are areas of high inflammatory activity. Intravital microscopy further revealed that neutrophils are the main cell population that interacts with atherosclerotic endothelium, suggesting an ongoing recruitment of neutrophils to lesions. These data demonstrate that neutrophils represen...

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