The dynactin p150glued subunit, encoded by the gene DCTN1 is part of the dynein-dynactin motor protein complex responsible for retrograde axonal transport. This subunit is a candidate modifier for neurodegenerative diseases, in particular motoneuron and extrapyramidal diseases. Based on an extensive screening effort of all 32 exons in more than 2,500 ALS/MND patients, patients suffering from Parkinsonian Syndromes and controls, we investigated 24 sequence variants of p150 in cell-based studies. We used both non-neuronal cell lines and primary rodent spinal motoneurons and report on cell biological abnormalities in five of these sequence alterations and also briefly report on the clinical features. Our results suggest the presence of biological changes caused by some p150 mutants pointing to a potential pathogenetic significance as modifier of the phenotype of the human disease.

Background: Hereditary diffuse leukodystrophy with spheroids is a rare type of leukoencephalopathy. Mutations in the colony stimulating factor 1 receptor have recently been identified to be the cause of this microgliopathy. Clinical and radiological presentation can often misguide physicians during the diagnosis of patients with this underdiagnosed disease. Case presentation: We present a 29 year-old woman with a rapid course of hereditary diffuse leukodystrophy with spheroids. She mainly showed cognitive impairment and severe motor dysfunctions. Her MRI showed spotted and confluent hyperintensities of the white matter on T2-weighted images involving the corticospinal tract as well as the corpus callosum. Further, those lesions showed striking restricted diffusion. As this restricted diffusion in all areas showing signs of leukoencephalopathy was so impressive we searched Medline for these terms and got hereditary diffuse leukodystrophy with spheroids as one of the first results. After a comprehensive diagnostic workup and exclusion of other leukoencephalopathies, stereotactic biopsy and genetic testing confirmed the diagnosis. Conclusion: This case points out at two important features of hereditary diffuse leukodystrophy with spheroids being spotted and/or confluent leukoencephalopathy with areas of restricted diffusion. This might help to identify more patients with this underdiagnosed disease. Moreover, the rapid clinical course in our patient raises the question whether the relatively pronounced areas of restricted diffusion are indicative of a more acute progression of the disease.

The dynactin p150(Glued) subunit, encoded by the gene DCTN1, is part of the dynein-dynactin motor protein complex responsible for retrograde axonal transport in motor neurons. The p150 subunit is a candidate gene for neurodegenerative diseases, in particular motor neuron and extrapyramidal diseases. Tubulin-binding cofactors are believed to be involved in tubulin biogenesis and degradation and therefore to contribute to microtubule functional diversity and regulation. A yeast-two-hybrid screen for putative interacting proteins of dynactin p150(Glued) has revealed tubulin-folding cofactor B (TBCB). We analyzed the interaction of these proteins and investigated the impact of this complex on the microtubule network in cell lines and primary hippocampal neurons in vitro. We especially concentrated on neuronal morphology and synaptogenesis. Overexpression of both proteins or depletion of TBCB alone does not alter the microtubule network and/or neuronal morphology. The demonstration of the interaction of the transport molecule dynactin and the tubulin-regulating factor TBCB is thought to have an impact on several cellular mechanisms. TBCB expression levels have been found to have only a subtle influence on the microtubule network and neuronal morphology. However, overexpression of TBCB leads to the decreased localization of p150 to the microtubule network that might result in a functional modulation of this protein complex.

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