Calcineurin determines responses to?-synuclein

Calcineurin (CN) senses Ca2+ concentrations and transduces that information into cellular responses. Signaling through CN plays critical roles in processes ranging from stress response survival in yeast to mammalian development. Here, we report that?-syn, from yeast to neurons, leads to sustained highly elevated levels of cytoplasmic Ca2+, thereby activating a CaM-CN cascade that engages substrates that result in toxicity.

Firstly, we demonstrate that increasing levels of?-syn expression increase cytosolic Ca2+ concentrations. Mutations or aberrant expression of?-synuclein (?-syn), a major protein involved in the pathogenesis of PD, can induce Ca2+ overload and cell death. Midbrain dopaminergic (DA) neurons that overexpress Ca2+-binding proteins, which buffer intracellular Ca2+, are characteristically spared from degeneration.

Next, we show that partial calcineurin activity is necessary to protect against?-syn toxicity ex vivo and in vivo. CN function can be eliminated by deleting the regulatory subunit cnb1 alone or by the combined deletion of the catalytic subunits cna1 and cna2.

We examined NFAT activation in fixed postmortem tissue from humans diagnosed with PD or with a more aggressive synucleinopathy, dementia with Lewy bodies (DLB). The enhanced sensitivity of the SNc DA neurons to Ca2+ stress would exacerbate the defects in vesicle trafficking.

These findings have immediate therapeutic implications for synucleinopathies.

An important model system for differentiation is hematopoiesis, in which a single hematopoietic stem cell gives rise to a large number of cell types through a series of characterized intermediate progenitor cells. Its technical limitations slow down profiling of homogeneous differentiation intermediates. Here, we developed a high-sensitivity indexing-first ChIP approach to profile the dynamics of four chromatin modifications across 16 stages of hematopoietic differentiation.

The lower limit for genome-wide chromatin analysis is about 50,000 cells, for one cell nearly has 4 pg of DNA. We named the new approach the iChIP, which involving an initial chromatin barcoding step before ChIP with the desired antibody. We performed ChIP on the barcoded chromatin with an antibody to mono- and trimethylated histone H3 lysine 4 (H3K4me1 and H3K4me3). Totally, we have analyzed 48,415 enhancers (high H3K4me1/2 and low H3K4me3) and 17,923 promoters (highH3K4me3). Clustering of all 48,415 H3K4me1 peaks during hematopoiesis revealed 9 major clusters, in line with the underlying biology of the system.

To summary, iChIP enables the execution of reproducible and sensitive ChIP on only a few hundred cells. Combining our enhancer catalog with gene expression profiles, we elucidate the transcription factor network controlling chromatin dynamics and lineage specification in hematopoiesis.

Numerologist Warda is hooked on OG-L002 fishing, collecting. And lastly her encouragement comes from socializing along with her companions.