Myelin Proteomics: Molecular Anatomy of an Insulating Sheath

Fast-transmitting vertebrate axons are electrically insulated with multiple layers of nonconductive plasma membrane of glial cell origin, termed myelin. The myelin membrane is dominated by lipids, and its protein composition has historically been viewed to be of very low complexity. In this review, we discuss an updated reference compendium of 342 proteins associated with central nervous system myelin that represents a valuable resource for analyzing myelin biogenesis and white matter homeostasis. Cataloging the myelin proteome has been made possible by technical advances in the separation and mass spectrometric detection of proteins, also referred to as proteomics. This led to the identification of a large number of novel myelin-associated proteins, many of which represent low abundant components involved in catalytic activities, the cytoskeleton, vesicular trafficking, or cell adhesion. By mass spectrometry-based quantification, proteolipid protein and myelin basic protein constitute 17% and 8% of total myelin protein, respectively, suggesting that their abundance was previously overestimated. As the biochemical profile of myelin-associated proteins is highly reproducible, differential proteome analyses can be applied to material isolated from patients or animal models of myelin-related diseases such as multiple sclerosis and leukodystrophies

Polyene-lipids: A new tool to image lipids

Microscopy of lipids in living cells is currently hampered by a lack of adequate fluorescent tags. The most frequently used tags, NBD and BODIPY, strongly influence the properties of lipids, yielding analogs with quite different characteristics. Here, we introduce polyene-lipids containing five conjugated double bonds as a new type of lipid tag. Polyene-lipids exhibit a unique structural similarity to natural lipids, which results in minimal effects on the lipid properties. Analyzing membrane phase partitioning, an important biophysical and biological property of lipids, we demonstrated the superiority of polyene-lipids to both NBD- and BODIPY-tagged lipids. Cells readily take up various polyene-lipid precursors and generate the expected end products with no apparent disturbance by the tag. Applying two-photon excitation microscopy, we imaged the distribution of polyene-lipids in living mammalian cells. For the first time, ether lipids, important for the function of the brain, were successfully visualized

Peroxisomes and their central role in metabolic interaction networks in humans

Peroxisomes catalyze a number of essential metabolic functions and impairments in any of these are usually associated with major clinical signs and symptoms. In contrast to mitochondria which are autonomous organelles that can catalyze the degradation of fatty acids, certain amino acids and other compounds all by themselves, peroxisomes are non-autonomous organelles which are highly dependent on the interaction with other organelles and compartments to fulfill their role in metabolism. This includes mitochondria, the endoplasmic reticulum, lysosomes, and the cytosol. In this paper we will discuss the central role of peroxisomes in different metabolic interaction networks in humans, including fatty acid oxidation, ether phospholipid biosynthesis, bile acid synthesis, fatty acid alpha-oxidation and glyoxylate metabolism

Overexpression of peroxisomal testis-specific 1 protein induces germ cell apoptosis and leads to infertility in male mice

The overexpression of PXT1 in mouse testis leads to germ cell apoptosis and male infertility. The PXT1 protein contains a functional BH3-motif. PXT1 protein interacts with BAT3, and BAT3 is able to protect cells from PXT1-induced apoptosis

Treatment of High-grade Non–muscle-invasive Bladder Carcinoma by Standard Number and Dose of BCG Instillations Versus Reduced Number and Standard Dose of BCG Instillations: Results of the European Association of Urology Research Foundation Randomised Phase III Clinical Trial “NIMBUS”

Background: Intravesical instillation of bacillus Calmette-Guérin (BCG) is an accepted strategy to prevent recurrence of non–muscle-invasive bladder cancer (NMIBC) but associated with significant toxicity. Objective: NIMBUS assessed whether a reduced number of standard-dose BCG instillations are noninferior to the standard number and dose in patients with high-grade NMIBC. Design, setting, and participants: A total of 345 patients from 51 sites were randomised between December 2013 and July 2019. We report results after a data review and safety analysis by the Independent Data Monitoring Committee based on the cut-off date of July 1, 2019. Intervention: The standard BCG schedule was 6 wk of induction followed by 3 wk of maintenance at 3, 6, and 12 mo (15 instillations). The reduced frequency BCG schedule was induction at wks 1, 2, and 6 followed by 2 wk (wks 1 and 3) of maintenance at 3, 6, and 12 mo (nine instillations). Outcome measurements and statistical analysis: The primary endpoint was time to first recurrence. Secondary endpoints included progression to ≥ T2 and toxicity. Results and limitations: In total, 170 patients were randomised to reduced frequency and 175 to standard BCG. Prognostic factors at initial resection were as follows: Ta/T1: 46/54%; primary/recurrent: 92/8%; single/multiple: 57/43%; and concomitant carcinoma in situ: 27%. After 12 mo of median follow-up, the intention-to-treat analysis showed a safety-relevant difference in recurrences between treatment arms: 46/170 (reduced frequency) versus 21/175 patients (standard). Additional safety analyses showed a hazard ratio of 0.40 with the upper part of the one-sided 97.5% confidence interval of 0.68, meeting a predefined stopping criterion for inferiority. Conclusions: The reduced frequency schedule was inferior to the standard schedule regarding the time to first recurrence. Further recruitment of patients was stopped immediately to avoid harm in the reduced frequency BCG arm. Patient summary: After surgical removal of the tumour, patients with high-grade non–muscle-invasive bladder cancer are treated with bacillus Calmette-Guérin to prevent recurrence and progression. This is associated with significant side effects. We report the results of a clinical trial showing a reduction in the number of instillations (from 15 to nine in total) being inferior to the standard protocol. From today's perspective, complete tumour resection and a standard number of instillations remain the standard of care