Chance in our strands?

In keeping with the spirit of the article on which this perspective is based, a coin was tossed to decide the order of authors

Enhanced differentiation of the mouse oli-neu oligodendroglial cell line using optimized culture conditions

Abstract Objective Oligodendrocytes (OL) are the glial cell type in the CNS that are responsible for myelin formation. The ability to culture OLs in vitro has provided critical insights into the mechanisms underlying their function. However, primary OL cultures are tedious to obtain, difficult to propagate and are not easily conducive to genetic manipulation. To overcome these obstacles, researchers have generated immortalized OL like cell lines derived from various species. One such cell line is the mouse Oli-neu line which is thought to recapitulate characteristics of OLs in early stages of maturity. They have been extensively utilized in multiple studies as surrogates for OLs, especially in analyzing epigenetic modifications and regulatory pathways in the OL lineage. Results In this report we present the development of optimized culture media and growth conditions that greatly facilitate the differentiation of Oli-neu cells. Oli-neu cells differentiated using these new protocols exhibit a higher expression of myelin related genes and increased branching, both of which are defining characteristics of mature OLs, when compared to previous culture protocols. We envision that these new culture conditions will greatly facilitate the use of Oli-neu cells and enhance their ability to recapitulate the salient features of primary OLs

Glycogen synthase kinase 3β as a likely target for the action of lithium on circadian clocks

Although lithium is one of the most commonly used drugs in the prophylaxis and treatment of bipolar disorder, the mechanisms underlying its therapeutic action are still unclear. Together with its mood-stabilizing effects, lithium is also known to influence the circadian clocks of several organisms including man. Circadian rhythms are altered in patients with bipolar disorder, and it is believed that these rhythms may play an important role in disease mechanisms. It is therefore possible that some of the therapeutic actions of lithium may be related to its effect on circadian clocks. Identifying the targets for lithium's action on circadian clocks would therefore be important both for understanding the mechanisms of its therapeutic effect and also in further understanding disease mechanisms in bipolar disorders. Using Drosophila melanogaster as a model system, we show that long-term administration of lithium results in lengthening of the free-running period (t) of circadian locomotor activity rhythm of flies in constant darkness (DD). This effect occurs at concentrations similar to the plasma levels of lithium used in the treatment of bipolar disorder. The lithium-treated flies also show reduced activity of one of the previously reported targets of lithium action, Glycogen Synthase Kinase 3β (GSK 3β ). GSK 3β has been shown to be involved in the regulation of circadian clocks as the down regulation of this protein results in an elongation of t. The t elongation resembles the effect seen with lithium administration in a number of organisms including man, and taken together with the earlier observations our results suggest that lithium inhibits the activity of GSK 3β to produce its effect on circadian clocks

Identification of a novel 45 repeat unstable allele associated with a disease phenotype at the MJD1/SCA3 locus

We report a three generation Indian pedigree with the proband having 45 repeats at the Machado Joseph Disease (MJD)/spinocerebellar ataxia 3 (SCA3) disease locus. The proband exhibited clinical features of SCA and showed signs of cerebellar and brainstem atrophy on the MRI scan. The 45 repeat allele was unstable upon inter-generational transmission and was associated with a haplotype found in the majority of MJD/SCA3 patients from around the world. This is the smallest unstable allele reported till date at the MJD/SCA3 locus and may greatly reduce the gap between normal and pathological repeat ranges

Variants in the zinc transporter TMEM163 cause a hypomyelinating leukodystrophy

Hypomyelinating leukodystrophies comprise a subclass of genetic disorders with deficient myelination of the CNS white matter. Here we report four unrelated families with a hypomyelinating leukodystrophy phenotype harbouring variants in TMEM163 (NM_030923.5). The initial clinical presentation resembled Pelizaeus-Merzbacher disease with congenital nystagmus, hypotonia, delayed global development and neuroimaging findings suggestive of significant and diffuse hypomyelination. Genomic testing identified three distinct heterozygous missense variants in TMEM163 with two unrelated individuals sharing the same de novo variant. TMEM163 is highly expressed in the CNS particularly in newly myelinating oligodendrocytes and was recently revealed to function as a zinc efflux transporter. All the variants identified lie in highly conserved residues in the cytoplasmic domain of the protein, and functional in vitro analysis of the mutant protein demonstrated significant impairment in the ability to efflux zinc out of the cell. Expression of the mutant proteins in an oligodendroglial cell line resulted in substantially reduced mRNA expression of key myelin genes, reduced branching and increased cell death. Our findings indicate that variants in TMEM163 cause a hypomyelinating leukodystrophy and uncover a novel role for zinc homeostasis in oligodendrocyte development and myelin formation

Analysis of LMNB1 Duplications in Autosomal Dominant Leukodystrophy Provides Insights into Duplication Mechanisms and Allele-Specific Expression

Autosomal dominant leukodystrophy (ADLD) is an adult onset demyelinating disorder that is caused by duplications of the lamin B1 (LMNB1) gene. However, as only a few cases have been analyzed in detail, the mechanisms underlying LMNB1 duplications are unclear. We report the detailed molecular analysis of the largest collection of ADLD families studied, to date. We have identified the minimal duplicated region necessary for the disease, defined all the duplication junctions at the nucleotide level and identified the first inverted LMNB1 duplication. We have demonstrated that the duplications are not recurrent; patients with identical duplications share the same haplotype, likely inherited from a common founder and that the duplications originated from intrachromosomal events. The duplication junction sequences indicated that nonhomologous end joining or replication-based mechanisms such fork stalling and template switching or microhomology-mediated break induced repair are likely to be involved. LMNB1 expression was increased in patients’ fibroblasts both at mRNA and protein levels and the three LMNB1 alleles in ADLD patients show equal expression, suggesting that regulatory regions are maintained within the rearranged segment. These results have allowed us to elucidate duplication mechanisms and provide insights into allele-specific LMNB1 expression levels