Biology subjects

Cohn, R.

Publications and source records attributed to Cohn, R..

6 recordsLinked to original sources

bioRxiv2023

A cell-type-specific nitric oxide-cGMP pathway regulates proprioceptor morphology

Neurons show remarkable morphological diversity facilitated by transcriptional regulation during development and fitting with their connectivity and function. Second messenger pathways mediated by cyclic 3,5 adenosine or guanosine monophosphate (cAMP or cGMP) may serve to integrate extrinsic signals and regulate branching and growth of neurites. We investigated the regulation of cGMP signaling in neuronal morphogenesis in Drosophila somatosensory neurons and found cell type-specificity in expression of the enzyme soluble guanylate cyclase (sGC) in different sensory neuron classes. sGC is responsible for the production of cGMP in response to the diffusible free radical messenger nitric oxide (NO) such that different levels of sGC impart cell type-specific sensitivity to NO. Supporting a role for the NO-cGMP pathway in neuronal morphogenesis, we find that knockout of sGC or nitric oxide synthase (NOS) impacts the morphology of multidendritic proprioceptors. The homeodomain transcription factor Cut shows different levels of expression in different somatosensory neuron types and we find that Cut regulates the level of cGMP signaling via repression of sGC expression. Thus, transcription factor levels contribute to cell type diversification by regulating levels of a signaling pathway to mediate somatosensory neuron morphogenesis.

neuroscience↗

bioRxiv2021

An Efficient and Cost-effective Purification Methodology for Cas9 Nuclease

With an ever-increasing demand for laboratory-grade Cas9 proteins by many groups advancing the use of CRISPR technology, a more efficient and scalable process for generating the proteins, coupled with rapid purification methods is in urgent demand. Here, we introduce a modified methodology for rapid purification of active SaCas9 protein within 24 hours. The product has over 90% protein purity. The simplicity and cost-effectiveness of such methodology will enable general labs to produce a sizable amount of Cas9 proteins, further accelerating the advancement of CRISPR/Cas9-based research.

biochemistry↗

bioRxiv2021

Adult fibroblasts retain organ-specific transcriptomic identity

Organ fibroblasts are essential components of homeostatic and diseased tissues. They participate in sculpting the extracellular matrix, sensing the microenvironment and communicating with other resident cells. Recent studies have revealed transcriptomic heterogeneity among fibroblasts within and between organs. To dissect the basis of inter-organ heterogeneity, we compare the gene expression of fibroblasts from different tissues (tail, skin, lung, liver, heart, kidney, gonads) and show that they display distinct positional and organ-specific transcriptome signatures that reflect their embryonic origins. We demonstrate that fibroblasts expression of genes typically attributed to the surrounding parenchyma is established in embryonic development and largely maintained in culture, bioengineered tissues, and ectopic transplants. Targeted knockdown of key organ-specific transcription factors affects fibroblasts functions, with modulation of genes related to fibrosis and inflammation. Our data open novel opportunities for the treatment of fibrotic diseases in a more precise, organ-specific manner.

cell biology↗

bioRxiv2020

Transsynaptic mapping of Drosophila mushroom body output neurons

The Mushroom Body (MB) is a well-characterized associative memory structure within the Drosophila brain. Although previous studies have analyzed MB connectivity and provided a map of inputs and outputs, a detailed map of the downstream targets is missing. Using the genetic anterograde transsynaptic tracing tool, trans-Tango, we identified divergent projections across the brain and convergent downstream targets of the MB output neurons (MBONs). Our analysis revealed at least three separate targets that receive convergent input from MBONs: other MBONs, the fan shaped body (FSB), and the lateral accessory lobe (LAL). We describe, both anatomically and functionally, a multilayer circuit in which inhibitory and excitatory MBONs converge on the same genetic subset of FSB and LAL neurons. This circuit architecture provides an opportunity for the brain to update information and integrate it with previous experience before executing appropriate behavioral responses. Highlights-The postsynaptic connections of the output neurons of the mushroom body, a structure that integrates environmental cues with associated valence, are mapped using trans-Tango. -Mushroom body circuits are highly interconnected with several points of convergence among mushroom body output neurons (MBONs). -The postsynaptic partners of MBONs have divergent projections across the brain and convergent projections to select target neuropils outside the mushroom body important for multimodal integration. -Functional connectivity suggests the presence of multisynaptic pathways that have several layers of integration prior to initiation of an output response.

neuroscience↗

bioRxiv2020

Identifying dynamic protein and RNA proximity interaction networks of actinin reveals RNA-binding and metabolic regulatory mechanisms

RationaleActinins are actin cross-linkers that are ubiquitously expressed and harbor mutations in heritable diseases. The predominant cardiac actinin is encoded by ACTN2, which is a core structural component of the sarcomere Z-disk. ACTN2 is required for sarcomere function through complex interactions with proteins involved in sarcomere assembly, cell signaling and transcriptional regulation. However, there remain critical gaps in our knowledge of the complete and dynamic cardiac actinin interactome, which could reveal new insights into sarcomere biology. ObjectiveWe sought to examine the cardiac actinin interactome through sarcomere assembly in human cardiomyocytes. Methods and ResultsWe utilized CRISPR/Cas9, induced pluripotent stem cell technology and BioID to reveal cardiac actinin protein interactions in human cardiomyocytes. We identified 324 cardiac actinin proximity partners, analyzed networks, and studied interactome changes associated with sarcomere assembly. We focused additional studies on unexpected actinin interactions with effectors with RNA-binding functions. Using RNA immunoprecipitation followed by sequencing, we determined that RNA-binding partners uncovered by actinin BioID were bound to gene transcripts with electron transport chain and mitochondrial biogenesis functions. Mammalian two-hybrid studies established that IGF2BP2, an RNA-binding protein associated with type 2 diabetes, directly interacted with the rod domain of actinin through its K Homology domain. IGF2BP2 was necessary for electron transport chain transcript localization to vicinal RNA-binding proteins, mitochondrial mass and oxidative metabolism. IGF2BP2 knockdown also impaired sarcomere function in a cardiac microtissue assay. ConclusionsThis study expands our functional knowledge of cardiac actinin, uncovers new sarcomere interaction partners including those regulated by sarcomere assembly, and reveals sarcomere crosstalk with RNA-binding proteins including IGF2BP2 that are important for metabolic functions.

cell biology↗

bioRxiv2018

A contraction stress model of hypertrophic cardiomyopathy due to thick filament sarcomere mutations

Thick filament sarcomere mutations are the most common cause of hypertrophic cardiomyopathy (HCM), a disorder of heart muscle thickening associated with sudden cardiac death and heart failure, with unclear mechanisms. We engineered an isogenic panel of four human HCM induced pluripotent stem cell (iPSc) models using CRISPR/Cas9, and studied iPSc-derived cardiomyocytes (iCMs) in 3-dimensional cardiac microtissue (CMT) assays that resemble in vivo cardiac architecture and biomechanics. HCM mutations result in hypercontractility in association with prolonged relaxation kinetics in proportion to mutation pathogenicity but not calcium dysregulation. RNA sequencing and protein expression studies identified that HCM mutations result in p53 activation secondary to increased oxidative stress, which results in increased cytotoxicity that can be reversed by p53 genetic ablation. Our findings implicate hypercontractility as an early consequence of thick filament mutations, and the p53 pathway as a molecular marker and candidate therapeutic target for thick filament HCM.

cell biology↗