Biology subjects

Cohen, B. M.

Publications and source records attributed to Cohen, B. M..

5 recordsLinked to original sources

bioRxiv2025

Identifying and targeting abnormal mitochondrial localization associated with psychoses

Therapeutics working by novel mechanisms are needed for patients with psychiatric conditions. Cell-based assays to identify candidates that reverse observed abnormalities could accelerate the process. Here, we imaged peripheral cells (skin fibroblasts) of 168 patients, stained for DNA, actin, and mitochondria. We found mitochondria tend to be farther from the cell border for patients who experience psychosis (including subsets of individuals with bipolar disorder, schizophrenia, and schizoaffective disorder). We observed a reverse trend, albeit not statistically significant, for patients diagnosed with major depression. Because the phenotype could be identified by a single metric, we could query existing databases of cells stained for their mitochondria and treated with various chemical or genetic perturbations. We identified compounds and genes both negatively and positively affecting the psychosis-associated phenotype, including some known to impact psychiatric conditions. Developing therapeutics with novel mechanisms is a complex multi-step challenge. This cell-based assay holds promise for virtual and physical screening to identify candidates for treating psychiatric conditions.

systems biology↗

bioRxiv2022

SOX10 Expression Levels may be a Critical Mediator of White Matter Dysfunction in Schizophrenia.

Abnormalities of brain connectivity are consistently observed in individuals with schizophrenias (SZ). Underlying these anomalies, convergent in vivo, post-mortem, and genomic evidence suggest abnormal oligodendrocyte (OL) development and function, including lower in vivo myelination in SZ. Using patient derived induced pluripotent stem cells (IPSCs), we previously observed a significant and substantial reduction in the number of OLs produced in cells from the SZ group compared to the healthy control (HC) group. We a lso observed a correlation between white matter (WM) estimated in brain in vivo and the number of OLs produced in vitro. We have now characterized potential mediators that may contribute to the SZ-associated deficit in OL production. We ran qRT-PCRs to detect group-specific differences in key myelin pathway proteins. Significant reductions of PAX6 and SOX10 expression were seen in the SZ group. We focused on SOX10 since one of its functions is the commitment of precursor cells to an oligodendrocyte fate. Using an inducible lentiviral system, we expressed SOX10 in patterned neural stem cells (NSCs) and quantified the number of OLs produced. Expression of SOX10 rescued the SZ-associated deficit in OL production, indicating that reduced SOX10 may be a critical mediator of OL dysfunction in SZ. We then ran qRT-PCRs to screen mRNAs for three proteins (SOX9, QK1 and FEZ1) whose expression was directly influenced by SOX10 or directly influenced the expression of SOX10. We saw significant reductions of SOX9 expression and a reduction in QK1 expression in the SZ group. RNAseq analysis confirmed these gene expression changes.

neuroscience↗

bioRxiv2022

A global atlas of substrate specificities for the human serine/threonine kinome

Protein phosphorylation is one of the most widespread post-translational modifications in biology. With the advent of mass spectrometry-based phosphoproteomics, more than 200,000 sites of serine and threonine phosphorylation have been reported, of which several thousand have been associated with human diseases and biological processes. For the vast majority of phosphorylation events, it is not yet known which of the more than 300 protein Ser/Thr kinases encoded in the human genome is responsible. Here, we utilize synthetic peptide libraries to profile the substrate sequence specificity of nearly every functional human Ser/Thr kinase. Viewed in its entirety, the substrate specificity of the kinome was substantially more diverse than expected and was driven extensively by negative selectivity. Our kinome-wide dataset was used to computationally annotate and identify the most likely protein kinases for every reported phosphorylation site in the human Ser/Thr phosphoproteome. For the small minority of phosphosites where the protein kinases involved have been previously identified, our predictions were in excellent agreement. When this approach was applied to examine the signaling response of tissues and cell lines to hormones, growth factors, targeted inhibitors, and environmental or genetic perturbations, it revealed unexpected insights into pathway complexity and compensation. Overall, these studies reveal the full extent of substrate specificity of the human Ser/Thr kinome, illuminate cellular signaling responses, and provide a rich resource to link unannotated phosphorylation events to biological pathways.

systems biology↗

bioRxiv2017

Alternative Methods for Mitochondrial Transplantation: Efficiency of Unpackaged and Lipid-Packaged Preparations

Mitochondrial transplantation is currently being explored as a means to repair and restore proper organelle function in a variety of inherited and acquired disorders of energy metabolism. The optimal preparation and application of donor mitochondria is unknown, but most studies in vivo have used injection techniques or, for tissue studies, unpackaged mitochondria (organelles isolated and suspended in buffer) in transplant experiments. Packaging in lipid rafts can increase recipient cell uptake of some compounds and objects. We present the first data comparing recipient cell uptake of unpackaged mitochondria to recipient cell uptake of mitochondria packaged in cell membrane lipids. Mitochondria and membranes were prepared from autologous cells and applied to cells (fibroblasts) in culture. Both unpackaged and lipid-packaged mitochondria were taken into recipient cells and the donor mitochondria showed evidence, in each case, of retained functionality and the ability to merge with the recipient mitochondrial matrix. However, lipid packaging appeared to enhance the uptake of functional mitochondria. Current studies of mitochondrial transplantation in animal models might fruitfully explore the utility and efficacy of lipid-packaged mitochondria in transplant experiments.

molecular biology↗

bioRxiv2017

Gαq Mediates Clozapine Effects in Caenorhabditis elegans

Clozapine binds and has significant effects on multiple neurotransmitter receptors, notably including some dopamine receptors. Downstream of these receptors, clozapine affects the balance of Gi- and Gq-dependent second-messenger signaling. We used Caenorhabiditis elegans as a genetic model to study further how clozapine affects both dopamine receptors and downstream Gq mediated signaling. Four of six worm dopamine receptor orthologs, dop-1, dop-2, dop-4, and dop-5 produced resistance to clozapine induced developmental delay when mutated, suggesting that both type I and type II dopamine receptors mediate the behavioral effects of clozapine in C. elegans. Beyond these receptors, reduction of function of one of the G proteins, egl-30 (Gq), produced greatly increased susceptibility to clozapine. Gq has multiple known downstream effects. Among these is the control of acetylcholine release, which is in balance with monoamines in the human brain and is another target of clozapine and other antipsychotic drugs. We tested for downstream effects on acetylcholine at the neuromuscular junction upon clozapine treatment but found no evidence for effects of clozapine. In contrast, modulation of Gq upstream leads to worms that are either more resistant or more susceptible to clozapine, emphasizing the importance of Gq proteins in mediating effects of clozapine. A genetic screen for suppressors of egl-30 recovered eight mutants. By characterizing the behavioral effects of these mutants, we found that clozapine exerts its function on development by affecting Gq signaling through control of the pharyngeal pumping rate. A whole-genome sequencing technique was utilized and identified a list of candidate genes for these suppressor mutations. Further characterization of these mutants promises the discovery of novel components participating in Gq signaling and a better understanding of the mechanisms of action of clozapine.

genetics↗