The rockefeller university

Astrocytes are known to facilitate repair following brain injury; however, little is known about how injured astrocytes repair themselves. Repair of cell membrane injury requires Ca2+-triggered vesicle exocytosis. In astrocytes, lysosomes are the main Ca2+-regulated exocytic vesicles. Here we show that astrocyte cell membrane injury results in a large and rapid calcium increase. This triggers robust lysosome exocytosis where the fusing lysosomes release all luminal contents and merge fully with the plasma membrane. In contrast to this, receptor stimulation produces a small sustained calcium increase, which is associated with partial release of the lysosomal luminal content, and the lysosome membrane does not merge into the plasma membrane. In most cells, lysosomes express the synaptotagmin (Syt) isoform Syt VII; however, this isoform is not present on astrocyte lysosomes and exogenous expression of Syt VII on lysosome inhibits their exocytosis. Deletion of one of the most abundant Syt isoform in astrocyte - Syt XI - suppresses astrocyte lysosome exocytosis. This identifies lysosome as Syt XI-regulated exocytic vesicle in astrocytes. Further, inhibition of lysosome exocytosis (by Syt XI depletion or Syt VII expression) prevents repair of injured astrocytes. These results identify the lysosomes and Syt XI as the sub-cellular and molecular regulators, respectively of astrocyte cell membrane repair.

Objective: Assess the effectiveness of selected yoga postures in raising bone mineral density (BMD). Methods: Ten-year study of 741 Internet-recruited volunteers comparing preyoga BMD changes with postyoga BMD changes. Outcome Measures: Dual-energy x-ray absorptiometric scans. Optional radiographs of hips and spine and bone quality study (7 Tesla). Results: Bone mineral density improved in spine, hips, and femur of the 227 moderately and fully compliant patients. Monthly gain in BMD was significant in spine (0.0029 g/cm(2), P = .005) and femur (0.00022 g/cm(2), P =.053), but in 1 cohort, although mean gain in hip BMD was 50%, large individual differences raised the confidence interval and the gain was not significant for total hip (0.000357 g/cm(2)). No yoga-related serious injuries were imaged or reported. Bone quality appeared qualitatively improved in yoga practitioners. Conclusion: Yoga appears to raise BMD in the spine and the femur safely.

Despite the well-established role of the human serotonin transporter (hSERT) in the treatment of depression, the molecular details of antidepressant drug binding are still not fully understood. Here we utilize amber codon suppression in a membrane-bound transporter protein to encode photocrosslinking unnatural amino acids (UAAs) into 75 different positions in hSERT. UAAs are incorporated with high specificity, and functionally active transporters have similar transport properties and pharmacological profiles compared with wild-type transporters. We employ ultraviolet-induced crosslinking with p-azido-L-phenylalanine (azF) at selected positions in hSERT to map the binding site of imipramine, a prototypical tricyclic antidepressant, and vortioxetine, a novel multimodal antidepressant. We find that the two antidepressants crosslink with azF incorporated at different positions within the central substrate-binding site of hSERT, while no crosslinking is observed at the vestibular-binding site. Taken together, our data provide direct evidence for defining the high-affinity antidepressant binding site in hSERT.

N-methyl-D-aspartate receptors (NMDARs) are gluta-mate-gated, calcium-permeable ion channels that mediate synaptic transmission and underpin learning and memory. NMDAR dysfunction is directly implicated in diseases ranging from seizure to ischemia. Despite its fundamental importance, little is known about how the NMDAR transitions between inactive and active states and how small molecules inhibit or activate ion channel gating. Here, we report electron cryo-microscopy structures of the GluN1-GluN2B NMDA receptor in an ensemble of competitive antagonist-bound states, an agonist-bound form, and a state bound with agonists and the allosteric inhibitor Ro25-6981. Together with double electron-electron resonance experiments, we show how competitive antagonists rupture the ligand binding domain (LBD) gating "ring,'' how agonists retain the ring in a dimer-of- dimers configuration, and how allosteric inhibitors, acting within the amino terminal domain, further stabilize the LBD layer. These studies illuminate how the LBD gating ring is fundamental to signal transduction and gating in NMDARs.

Here we report the identification and verification of a beta-hydroxybutyrate-derived protein modification, lysine beta-hydroxybutyrylation (Kbhb), as a new type of histone mark. Histone Kbhb marks are dramatically induced in response to elevated beta-hydroxybutyrate levels in cultured cells and in livers from mice subjected to prolonged fasting or streptozotocin-induced diabetic ketoacidosis. In total, we identified 44 histone Kbhb sites, a figure comparable to the known number of histone acetylation sites. By ChIP-seq and RNA-seq analysis, we demonstrate that histone Kbhb is a mark enriched in active gene promoters and that the increased H3K9bhb levels that occur during starvation are associated with genes upregulated in starvation-responsive metabolic pathways. Histone beta-hydroxybutyrylation thus represents a new epigenetic regulatory mark that couples metabolism to gene expression, offering a new avenue to study chromatin regulation and diverse functions of beta-hydroxybutyrate in the context of important human pathophysiological states, including diabetes, epilepsy, and neoplasia.

Rescue in vitro maturation (IVM) is currently not a routine procedure in association with in vitro fertilization (IVF). We compared in a prospectively cohort study of 10 patients with normal functional ovarian reserve (NFOR) and of 25 with low functional ovarian reserve (LFOR), defined by abnormally high FSH and/or abnormally low AMH levels), IVM dynamics of immature oocytes. Following controlled ovarian hyperstimulation in IVF cycles, only immature oocytes underwent rescue IVM (for up to 48 h). Oocyte maturation dynamics, fertilization rates, embryo development, and pregnancy rates were then compared between NFOR and LFOR patients. Though proportion of MI and GV oocytes reaching MII stages within 48 h and rate of maturation of MI oocytes did not differ, in women with LFOR significantly more GV oocytes reached MII stage within 24 h (30.4 vs. 66.9 %; P = 0.013), while fertilization rates and embryo generation numbers were similar between both groups. Rescue IVM, thus, produced 1.5 additional embryos for transfer in women with LFOR and 1.6 in patients with NFOR, a highly significant difference in relative improvement in available embryo numbers for LFOR (+60.0 %) and NFOR women (+16.5 %). Rescue IVM, thus, not only demonstrates different time dynamics between women with LFOR and NFOR but also disproportionate efficacy in improving available embryo numbers for transfer in favor of LFOR patients. 1/7 patients, who reached embryo transfer with only embryos produced via rescue IVF conceived and delivered, proving that rescue IVF in women with LFOR also improves pregnancy and delivery chances. Because of the small number of embryos LFOR patients produce, every additional embryo is of considerable potential clinical significance for them, suggesting that rescue IVM in women with LFOR should become routine practice.

Adult tissue stem cells (SCs) reside in niches, which orchestrate SC behavior. SCs are typically used sparingly and exist in quiescence unless activated for tissue growth. Whether parsimonious SC use is essential to conserve long-term tissue-regenerating potential during normal homeostasis remains poorly understood. Here, we examine this issue by conditionally ablating a key transcription factor Forkhead box C1 (FOXC1) expressed in hair follicle SCs (HFSCs). FOXC1-deficient HFSCs spend less time in quiescence, leading to markedly shortened resting periods between hair cycles. The enhanced hair cycling accelerates HFSC expenditure, and impacts hair regeneration in aging mice. Interestingly, although FOXC1-deficient HFs can still form a new bulge that houses HFSCs for the next hair cycle, the older bulge is left unanchored. As the new hair emerges, the entire old bulge, including its reserve HFSCs and SC-inhibitory inner cell layer, is lost. We trace this mechanism first, to a marked increase in cell cycle-associated transcripts upon Foxc1 ablation, and second, to a downstream reduction in E-cadherin-mediated inter-SC adhesion. Finally, we show that when the old bulge is lost with each hair cycle, overall levels of SC-inhibitory factors are reduced, further lowering the threshold for HFSC activity. Taken together, our findings suggest that HFSCs have restricted potential in vivo, which they conserve by coupling quiescence to adhesion-mediated niche maintenance, thereby achieving long-term tissue homeostasis.

As B cells engage in the immune response, they express activation-induced cytidine deaminase (AID) to initiate the hypermutation and recombination of immunoglobulin genes, which are crucial processes for the efficient recognition and disposal of pathogens. However, AID must be tightly controlled in B cells to minimize off-target mutations, which can drive chromosomal translocations and the development of B cell malignancies, such as lymphomas. Recent genomic and biochemical analyses have begun to unravel the mechanisms of how AID-mediated deamination is targeted outside immunoglobulin genes. Here, we discuss the transcriptional and topological features that are emerging as key drivers of AID promiscuous activity.