Biology subjects

Du, G.

Publications and source records attributed to Du, G..

35 records · Page 2Linked to original sources

bioRxiv2023

Cooperative progression of colitis and leukemia modulated by clonal hematopoiesis via PTX3/IL-1β pro-inflammatory signaling

Clonal hematopoiesis (CH) is considered an important risk factor for all-cause mortality and the development of multiple chronic diseases including hematological neoplasms, cardiovascular diseases, and potentially a range of autoimmune or immune-deficiency diseases. Mutations in TET2 are one of the first identified, most important, and prevalent genetic drivers of CH. However, cooperative factors and mechanisms underlying TET2-deficiency related CH (TedCH) remain largely unknown. Recently, it has been suggested that certain diseases occurred before TedCH and promote TedCH trajectory on the contrary, indicating that diseases in non-hematopoietic organs may act as environmental non-genetic drivers of CH. To clarify the relationships between immune-dysfunctional diseases and CH, here we tested the impact of various challenges on TedCH. We found that expedited TedCH depended on establishment of an inflammatory environment. Primary or chimeric Tet2-mutant mice spontaneously developed co-symptoms reminiscent of human chronic colitis and myeloid leukemia, which was exacerbated by feeding with DSS, an experimental inducer of ulcerative colitis. Single cell RNA-seq (scRNA-seq) analysis reveals in depth the damage of colon in the Tet2-mutant mice in physiological conditions or fed with DSS, along with increase of dysbacteriosis indicated by gut microbiome analysis. Results from colon scRNA-seq from both mouse and human highlight the important roles of PTX3/IL-1{beta} pro-inflammatory signaling in promoting colitis or leukemia. Finally, TedCH trajectory and inflammation in colon and bone marrow were ameliorated by treatment of IL-1R1 inhibitor Anakinra. Our study suggests that PTX3/IL-1{beta} signaling and clonal hematopoiesis cooperate and play important roles in gut-bone marrow axis and related diseases including colitis and leukemia. HighlightsO_LICertain environmental factors, such as Dextran Sulfate Sodium (DSS), an experimental inducer of ulcerative colitis, promote TedCH C_LIO_LIColitis and leukemia are spontaneously and simultaneously developed in Tet2-defficient primary or chimeric mice, along with increased pathogenic gut microbiomes, indicating an aberrant gut-bone marrow axis in the mutant mice. C_LIO_LISingle cell RNA-seq analysis reveals enhanced PTX3, a soluble pattern recognition molecule and IL-1{beta} pro-inflammatory signaling in colitis and leukemia. C_LIO_LIThe In vivo function of the PTX3/IL-1{beta} pro-inflammatory signaling in TedCH is indicated in human colitis and validated in experimental settings. C_LI

immunology↗

bioRxiv2023

Optogenetic strategies for optimizing the performance of biosensors of membrane phospholipids in live cells

High-performance biosensors play a crucial role in elucidating the intricate spatiotemporal regulatory roles and dynamics of membrane lipids. However, enhancing their sensitivity and substrate-detecting capabilities remains a significant challenge. Here, we presented optogenetic-based strategies to optimize phospholipid biosensors. These strategies involved pre-sequestering unbound probes in the cell nucleus to minimize background signals in the cytoplasm. These stored probes could be released from the nucleus in response to blue light according to experimental requirements. Furthermore, we employed optically-controlled phase separation to generate punctate probes that amplified signals and facilitated the visualization of phospholipids in cells. These improved phospholipid biosensors hold great potential for enhancing our understanding of the spatiotemporal dynamics and regulatory roles of membrane lipids in live cells and this methodological insights might be valuable for developing other high-performance biosensors.

cell biology↗

bioRxiv2023

Spatio-temporal patterns of ovarian development and VgR gene silencing reduced fecundity of parthenogenetic Artemia

Halophilic zooplankton brine shrimp Artemia has been used as an experimental animal in multidisciplinary research. However, the reproductive patterns and regulation mechanisms of Artemia remain a mystery. In this study, the ovarian development process of parthenogenetic Artemia (P. Artemia) was distinguished into five stages, and oogenesis or egg formation process was identified with six phases. The mode of oogenesis was assumed polytrophic. Moreover, we traced the dynamic translocation of germline stem cells (GSCs) by EdU labeling, elucidated several key cytological events in oogenesis through HE staining and florescent image. Notably, distinguished from the ovary structure of insects and crustaceans, P. Artemia germarium originated from ovariole buds and located in the base of the ovarioles. RNA-seq based on five stages of ovarian development revealed that 2657 up-regulated genes related to reproduction were obtained by pair-to-pair comparison of RNA-seq. Furthermore, Gbb, Dpp, piwi, vasa, nanos, VgA and VgR associated with GSCs recognition and reproductive development genes were screened and also verified by qPCR. Silencing of the VgR gene in P. Artemia (PA-VgR) at stage L of ovarian development led to a low level of gene expression (<10%) within five days, which resulted variations of oogenesis-related gene expression and significantly inhibited vitellogenesis, impeded oocyte maturation, and eventually decreased the offspring number. In conclusion, we illustrated the patterns of ovarian development, outlined the key spatio-temporal features of oogenesis and established a platform for gene function research using P. Artemia as an experimental animal. These results lay the foundation for studying the reproductive biology of invertebrates, may also provide a novel insight in the reproductive regulation mechanism of aquatic animals in extreme environments. SUMMARY STATEMENTArtemia is a novel experimental platform and potential "model" crustacean for studying specific process and mechanism of reproduction.

developmental biology↗

bioRxiv2023

ROS-dependent palmitoylation is an obligate licensing modification for GSDMD pore formation

Gasdermin D (GSDMD) is the common effector for cytokine secretion and pyroptosis downstream of inflammasome activation by forming large transmembrane pores upon cleavage by inflammatory caspases. Here we report the surprising finding that GSDMD cleavage is not sufficient for its pore formation. Instead, GSDMD is lipidated by S-palmitoylation at Cys191 upon inflammasome activation, and only palmitoylated GSDMD N-terminal domain (GSDMD-NT) is capable of membrane translocation and pore formation, suggesting that palmitoylation licenses GSDMD activation. Treatment by the palmitoylation inhibitor 2-bromopalmitate and alanine mutation of Cys191 abrogate GSDMD membrane localization, cytokine secretion, and cell death, without affecting GSDMD cleavage. Because palmitoylation is formed by a reversible thioester bond sensitive to free thiols, we tested if GSDMD palmitoylation is regulated by cellular redox state. Lipopolysaccharide (LPS) mildly and LPS plus the NLRP3 inflammasome activator nigericin markedly elevate reactive oxygen species (ROS) and GSDMD palmitoylation, suggesting that these two processes are coupled. Manipulation of cellular ROS by its activators and quenchers augment and abolish, respectively, GSDMD palmitoylation, GSDMD pore formation and cell death. We discover that zDHHC5 and zDHHC9 are the major palmitoyl transferases that mediate GSDMD palmitoylation, and when cleaved, recombinant and partly palmitoylated GSDMD is 10-fold more active in pore formation than bacterially expressed, unpalmitoylated GSDMD, evidenced by liposome leakage assay. Finally, other GSDM family members are also palmitoylated, suggesting that ROS stress and palmitoylation may be a general switch for the activation of this pore-forming family. One-Sentence SummaryGSDMD palmitoylation is induced by ROS and required for pore formation

immunology↗

bioRxiv2023

Development of Multiomics in situ Pairwise Sequencing (MiP-Seq) for Single-cell Resolution Multidimensional Spatial Omics

Delineating the spatial multiomics landscape will pave the way to understanding the molecular basis of physiology and pathology. However, current spatial omics technology development is still in its infancy. Here, we developed a high-throughput multiomics in situ pairwise sequencing (MiP-Seq) strategy to efficiently decipher multiplexed DNAs, RNAs, proteins, and small biomolecules at subcellular resolution. We delineated dynamic spatial gene profiles in the hypothalamus using MiP-Seq. Moreover, MiP-Seq was unitized to detect tumor gene mutations and allele-specific expression of parental genes and to differentiate sites with and without the m6A RNA modification at specific sites. MiP-Seq was combined with in vivo Ca2+ imaging and Raman imaging to obtain a spatial multiomics atlas correlated to neuronal activity and cellular biochemical fingerprints. Importantly, we proposed a "signal dilution strategy" to resolve the crowded signals that challenge the applicability of in situ sequencing. Together, our method improves spatial multiomics and precision diagnostics and facilitates analyses of cell function in connection with gene profiles.

molecular biology↗

bioRxiv2021

Hyperactive chemotaxis contributes to anti-TNFα treatment resistance in inflammatory bowel disease

Background & AimsAnti-tumour necrosis factor-alpha (anti-TNF) agents have been used for inflammatory bowel disease (IBD), however, it has up to 30% non-response rate. Identifying molecular pathways and finding reliable diagnostic biomarkers for patient response to anti-TNF treatment are clearly needed. MethodsPublicly available transcriptomic data from IBD patients receiving anti-TNF therapy was systemically collected and integrated. In silico flow cytometry approaches and MetaScape were applied to evaluate immune cell populations and to perform gene enrichment analysis, respectively. Genes identified within enrichment pathways validated in neutrophils were tracked in an anti-TNF-treated animal model (with lipopolysaccharide (LPS)-induced inflammation). The receiver operating characteristic (ROC) curve was applied to all genes to identify the best prediction biomarkers. ResultsA total of 449 samples were retrieved from control, baseline and after primary anti-TNF therapy or placebo. No statistically significant differences were observed between anti-TNF treatment responders and non-responders at baseline in immune microenvironment scores. Neutrophils, endothelial and B cell populations were higher in baseline non-responders and chemotaxis pathways may contribute to the treatment resistance. Genes related to chemotaxis pathways were significantly up-regulated in LPS-induced neutrophils but no statistically significant changes were observed in neutrophils treated with anti-TNF. Interleukin 13 receptor subunit alpha 2 (IL13RA2) is the best predictor (ROC: 80.7%, 95% CI: 73.8% - 87.5%) with a sensitivity of 68.13% and specificity of 84.93%, and significantly higher in non-responders compared to responders (p < 0.0001). ConclusionsHyperactive chemotaxis influences responses to anti-TNF treatment and IL13RA2 is a potential biomarker to predict anti-TNF treatment response.

molecular biology↗

bioRxiv2021

Transcription factor-like 5 is a potential DNA/RNA-binding protein essential for maintaining male fertility in mice.Running title: Tcfl5 is haploinsufficient in vivo

Tissue-specific transcription factors often play key roles in the development of specific cell lineages. Transcription factor-like 5 (TCFL5) is a testis-specific protein that contains the basic helix-loop-helix domain, although the in vivo functions of TCFL5 remain unknown. Herein, we generated CRISPR/Cas9-mediated knockout mice to dissect the function of TCFL5 in mouse testes. Surprisingly, we found that it was difficult to generate homozygous mice with the Tcfl5 deletion since the heterozygous males (Tcfl5+/-) were infertile. We did, however, observe markedly abnormal phenotypes of spermatids and spermatozoa in the testes and epididymides of Tcfl5+/- mice. Mechanistically, we demonstrated that TCFL5 transcriptionally regulated a set of genes participating in male germ cell development, which we uncovered via RNA-sequencing and TCFL5 ChIP-sequencing. We also found that TCFL5 interacted with RNA-binding proteins (RBPs) that regulated RNA processing, and further identified the fragile X mental retardation gene 1, autosomal homolog (FXR1, a known RBP) as an interacting partner of TCFL5 that may coordinate the transition and localization of TCFL5 in the nucleus. Collectively, we herein report for the first time that Tcfl5 is haploinsufficient in vivo and hypothesize that TCFL5 may be a dual-function protein that mediates DNA and RNA to regulate spermatogenesis.

cell biology↗

bioRxiv2021

Decoupling of global brain activity and cerebrospinal fluid flow in Parkinson's cognitive decline

BackgroundDeposition and spreading of misfolded proteins (-synuclein and tau) have been linked to Parkinsons cognitive dysfunction. The glymphatic system may play an important role in the clearance of these toxic proteins via cerebrospinal fluid (CSF) flow through perivascular and interstitial spaces. Recent studies discovered that sleep-dependent global brain activity is coupled to CSF flow that may reflect glymphatic function. ObjectiveTo determine if the decoupling of brain activity-CSF flow is linked to Parkinsons cognitive dysfunction. MethodsFunctional and structural MRI data, clinical motor (Unified Parkinson's Disease Rating Scale), and cognitive (Montreal Cognitive Assessment, MoCA) scores were collected from 60 Parkinsons and 58 control subjects. Parkinsons patients were subgrouped into those with (MoCA < 26; N = 29) and without (MoCA [≥] 26; N = 31) mild cognitive impairment (MCI). The coupling strength between the resting-state global blood-oxygen-level-dependent signal (gBOLD) and associated CSF flow was quantified, compared among groups, and associated with clinical and structural measurements. ResultsgBOLD-CSF coupling decreased significantly (p < 0.006) in Parkinsons patients showing MCI, compared to those without MCI and controls. Reduced gBOLD-CSF coupling was associated with decreased MoCA scores that was present in Parkinsons patients (p = 0.005) but not in controls (p = 0.65). Weaker gBOLD-CSF coupling in Parkinsons patients also was associated with a thinner right entorhinal cortex (Spearmans correlation = - 0.36; p = 0.012), an early structural change often seen in Alzheimers. ConclusionsThe decoupling between global brain activity and associated CSF flow is related to Parkinsons cognitive impairment.

neuroscience↗

bioRxiv2020

A framework for predicting potential host ranges of pathogenic viruses based on receptor ortholog analysis

Viral zoonoses are a serious threat to public health and global security, as reflected by the current scenario of the growing number of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) cases. However, as pathogenic viruses are highly diverse, identification of their host ranges remains a major challenge. Here, we present a combined computational and experimental framework, called REceptor ortholog-based POtential virus hoST prediction (REPOST), for the prediction of potential virus hosts. REPOST first selects orthologs from a diverse species by identity and phylogenetic analyses. Secondly, these orthologs is classified preliminarily as permissive or non-permissive type by infection experiments. Then, key residues are identified by comparing permissive and non-permissive orthologs. Finally, potential virus hosts are predicted by a key residue-specific weighted module. We performed REPOST on SARS-CoV-2 by studying angiotensin-converting enzyme 2 orthologs from 287 vertebrate animals. REPOST efficiently narrowed the range of potential virus host species (with 95.74% accuracy).

microbiology↗

bioRxiv2020

A pathway of NADPH diaphorase positivity between central canal and pial surface at anterior fissure in spinal cord: Supra fissure area with hypothesis configuring from dog, rat, monkey and pigeon

The spinal cord is a cylinder structure in the vertebra and thought a simplified with the gray matter and white matter. Rexed lamination for the gray matter and regional sub-division for whiter matter are completely termed to date. Anterior commissure locates between the central canal and the anterior median fissure. However, some experimental data may still confront with new confined anatomical interpretation. By using NADPH diaphorase [N-d] enzyme histology, we found a vertical oriented neuronal pathway between the central canal and the anterior median fissure in the sacral spinal cord of young adult and aged dog. We used a term "supra fissure area" [SFA] to illustrate the region which consisted of the gray commissure and anterior white commissure. The N-d pathway was notably observable in aged animals. The vertical neurites revealed the cerebrospinal fluid [CSF] contacting neurites between the anterior median fissure and the central canal. We further examined the monkey, rat and pigeon in the region for better understanding of the structure and potential function. The neurodegeneration of N-d dystrophy was detected in the [SFA] in the thoracic spinal cord of the aged monkey. N-d positive fibers were detected in anterior fissure of the rat spinal cord. N-d fibrous structures were also detected in the pigeon spinal cord. These results suggested a new pathway of CSF contacting neurons and the neuronal communications about the central canal.

neuroscience↗

bioRxiv2019

NADPH diaphorase neuronal dystrophy in gracile nucleus, cuneatus nucleus and spinal trigeminal nucleus in aged rat

NADPH-diaphorase (N-d) activity is commonly used to identify NOS-ergic neurons. In our previous study, N-d positive neuritic dystrophy and spheroid termed aging-related N-d Body is discovered in the lumbosacral spinal cord in the normal aging rats. Histological studies also reveal that N-d positive neurodegenerative changes occur in the gracile nucleus. We re-examined N-d activity in gracile nucleus in aged rat. We found N-d positive neuritic dystrophy and spheroid also occurred in the cuneatus nucleus and spinal trigeminal nucleus. Besides regular coronal section, longitudinal oriented dystrophic neurites were detected in the sagittal and horizontal section in gracile nucleus and dorsal column. We fziurther examined the medullary oblongata with regular classical histology including Golgi staining, immunocytochemistry of NOS and phosphorylated tau protein, neuronal tracing method with wheat germ agglutinin conjugated alexa-fluor-488 through sciatic nerve, and spinal cord transection at thoracic level. Most of N-d positive neuritic dystrophy and spheroid did not showed colocalization with NOS or phosphorylated tau protein. Neuronal tracing and spinal cord transection revealed that N-d dystrophic neurites in gracile nucleus originated from terminal of sensory projection from spinal cord and peripheral somatic input. The results suggested that aging-related N-d dystrophy in the gracile nucleus was unique morphological feature. In conclusion, it was postulated that the N-d dystrophy as a morphological marker of aging degenerative damage in normal aged organisms.

neuroscience↗

bioRxiv2019

DeepHiC: A Generative Adversarial Network for Enhancing Hi-C Data Resolution

Hi-C is commonly used to study three-dimensional genome organization. However, due to the high sequencing cost and technical constraints, the resolution of most Hi-C datasets is coarse, resulting in a loss of information and biological interpretability. Here we develop DeepHiC, a generative adversarial network, to predict high-resolution Hi-C contact maps from low-coverage sequencing data. We demonstrated that DeepHiC is capable of reproducing high-resolution Hi-C data from as few as 1% downsampled reads. Empowered by adversarial training, our method can restore fine-grained details similar to those in high-resolution Hi-C matrices, boosting accuracy in chromatin loops identification and TADs detection, and outperforms the state-of-the-art methods in accuracy of prediction. Finally, application of DeepHiC to Hi-C data on mouse embryonic development can facilitate chromatin loop detection with higher accuracy. We develop a web-based tool (DeepHiC, http://sysomics.com/deephic) that allows researchers to enhance their own Hi-C data with just a few clicks.\n\nAuthor summaryWe developed a novel method, DeepHiC, for enhancing Hi-C data resolution from low-coverage sequencing data using generative adversarial network. DeepHiC is capable of reproducing highresolution (10-kb) Hi-C data with high quality even using 1/100 downsampled reads. Our method outperforms the previous methods in Hi-C data resolution enhancement, boosting accuracy in chromatin loops identification and TADs detection. Application of DeepHiC on mouse embryonic development data shows that enhancements afforded by DeepHiC facilitates the chromatin loops identification of these data achieving higher accuracy. We also developed a user-friendly web server (http://sysomics.com/deephic) that allows researchers to enhance their own low-resolution Hi-C data (40kb-1 Mb) with just few clicks.

bioinformatics↗

bioRxiv2019

Identification of NAD-dependent xylitol dehydrogenase from Gluconobacter oxydans WSH-003

Gluconobacter oxydans plays important role in conversion of D-sorbitol to L-sorbose, which is an essential intermediate for industrial-scale production of vitamin C. In the fermentation process, some D-sorbitol could be converted to D-fructose and other byproducts by uncertain dehydrogenases. Genome sequencing has revealed the presence of diverse genes encoding dehydrogenases in G. oxydans. However, the characteristics of most of these dehydrogenases remain unclear. Therefore, analyses of these unknown dehydrogenases could be useful for identifying those related to the production of D-fructose and other byproducts. Accordingly, dehydrogenases in G. oxydans WSH-003, an industrial strain used for vitamin C production, were examined. An NAD-dependent dehydrogenase, which was annotated as xylitol dehydrogenase 2, was identified, codon-optimized, and expressed in Escherichia coli BL21 (DE3) cells. The enzyme exhibited high preference for NAD+ as the cofactor, while no activity with NADP+, FAD, or PQQ was noted. Although this enzyme presented high similarity with NAD-dependent xylitol dehydrogenase, it showed high activity to catalyze D-sorbitol to D-fructose. Unlike the optimum temperature and pH for most of the known NAD-dependent xylitol dehydrogenases (30{degrees}C-40{degrees}C and about 6-8, respectively), those for the identified enzyme were 57{degrees}C and 12, respectively. The Km and Vmax of the identified dehydrogenase towards L-sorbitol were 4.92 M and 196.08 M/min, respectively. Thus, xylitol dehydrogenase 2 can be useful for cofactor NADH regeneration under alkaline conditions or its knockout can improve the conversion ratio of D-sorbitol to L-sorbose.\n\nImportanceProduction of L-sorbose from D-sorbitol by Gluconobacter oxydans is the first step for industrial scale production of L-ascorbic acid. G. oxydans contains a lot of different dehydrogenases, among which only several are responsible for the conversion of D-sorbitol to L-sorbose, while others may responsible for the accumulation of byproducts, thus decreased the yield of L-sorbose on D-sorbitol. Therefore, a new xylitol dehydrogenase has been identified from 44 dehydrogenases of G. oxydans. Optimum temperature and pH of the xylitol dehydrogenase are different to most of the known ones. Knock-out of the dehydrogenase may improve the conversion ratio of D-sorbitol to L-sorbose. Besides, the enzyme exhibits high preference for NAD+ and have potential to be used for cofactor regeneration.

bioengineering↗

bioRxiv2019

Dual forms of aging-related NADPH diaphorase neurodegeneration in the sacral spinal cord of aged non-human primates

We discovered two different anomalous NADPH diaphorase (NADPH-d) positive alterations, which were expressed as aging-related NADPH-d positive spheroidal bodies and megaloneurites specially distributed in the superficial dorsal horn, dorsal gray commissure (DGC), lateral collateral pathway (LCP) and sacral parasympathetic nucleus (SPN) in the aged monkeys sacral spinal cord, compared with the cervical, thoracic and lumbar segments. In the gracile nucleus of aged monkeys, only aging-related spheroidal bodies were observed and no megaloneurites occurred. The dense, abnormal NADPH-d positive megaloneurites, extremely different from regular NADPH-d positive fibers, were prominent in the sacral segments and occurred in extending from Lissauers tract (LT) through lamina I along the lateral boundary of the dorsal horn to the region of the SPN. Meanwhile, large diameter punctate NADPH-d activity occurred and scattered in the lateral white matter of the LCP and dorsal root entry zone (DREZ) at the same level of NADPH-d abnormality in the gray matters. Those dot-like NADPH-d alterations were examined by horizontal sectioning and indicated ascending or descending oriental fibers. These NADPH-d megaloneurites had the same composition as the punctate NADPH-d alterations and were co-localized with the VIP immunoreaction, while the ANBs did not coexist with the VIP immunoreaction. Both ANBs and megaloneurites provide consistent evidence that the anomalous neuritic alterations in the aged sacral spinal cord are referred to as a specialized aging marker in the pelvic visceral organs in non-human primates.

neuroscience↗

bioRxiv2018

De novo aging-related meganeurites: alteration of NADPH diaphorase positivity in the sacral spinal cord of the aged dog

The aging-related changes of NADPH-diaphorase (NADPH-d) in the spinal cord were studied in aged dogs. At all levels of the spinal cord examined, NADPH-d activities were present in neurons and fibers in the superficial dorsal horn, dorsal commissure and in neurons around the central canal. In addition, the sympathetic autonomic nucleus in the thoracic and rostral lumbar segments exhibited prominent NADPH-d cellular staining whereas the sacral parasympathetic nucleus (SPN) in the sacral segments was not well stained. Interestingly, we found abundant NADPH-d positive enlarged-diameter fibers termed megaloneurite, which characteristically occurred in the aged sacral segments, distributed in the dorsal gray commissure (DGC), lateral collateral pathway (LCP) the lateral fasciculi and the central canal compared with the cervical, thoracic and lumbar segments. The dense, abnormal NADPH-d megaloneurites occurred in extending from dorsal entry zone through lamina I along with the lateral boundary of the dorsal horn to the region of the SPN. These fibers were prominent in the S1-S3 segments but not in adjacent segments L5-L7 and Cx1 or in thoracolumbar segments and cervical segments. Double staining with GFAP, NeuN, CGRP, MAP2 and Iba1, NADPH-d megaloneurite colocalized with vasoactive intestinal peptide. Presumably, the megaloneurites may represent, in part, visceral afferent projections to the SPN and/or DGC. The NADPH-d megaloneurites in the aged sacral spinal cord indicated some anomalous changes in the neurites, which might account for a disturbance in the aging pathway of the autonomic and sensory nerve in the pelvic visceral organs.

neuroscience↗

bioRxiv2018

Bile acids target proteolipid nano-assemblies of EGFR and phosphatidic acid in the plasma membrane for stimulation of MAPK signaling

Bile acids are critical biological detergents in the gastrointestinal tract and also act as messengers to regulate a multitude of intracellular signaling events, including mitogenic signaling, lipid metabolism and endo/exocytosis. In particular, bile acids stimulate many receptors and ion channels on the cell surface, the mechanisms of which are still poorly understood. Membrane-associating proteins depend on the local spatial distribution of lipids in the plasma membrane (PM) for their function. Here, we report that the highly amphipathic secondary bile acid deoxycholic acid (DCA), a major constituent in the human bile, at doses <1M enhances the nanoclustering of phosphatidic acid (PA) but disrupts the local segregation of phosphoinositol 4,5-bisphosphate (PIP2) in the basolateral PM of the human colorectal adenocarcinoma Caco-2 cells. PA has been shown to be a key structural component of the signaling nano-domains of epidermal growth factor receptor (EGFR) on the cell surface. We show that DCA promotes the co-localization between PA and EGFR, the PA-driven EGFR dimerization/oligomerization and EGFR signaling. Depletion of PA abolishes the stimulatory effects of DCA on the EGFR oligomerization and signaling. This effect occurs in the cultured Caco-2 cells and the ex vivo human intestinal enteroids. We propose a novel mechanism, where the amphiphilic DCA monomers alter the nano-assemblies of anionic phospholipids and in turn change the dynamic structural integrity of the lipid-driven oligomerization of cell surface receptors and their signal transduction.

biophysics↗

bioRxiv2016

Compromised External Validity: Federally Produced Cannabis Does Not Reflect Legal Markets

As the most widely used illicit drug, the basis of the fastest growing major industry in the US, and as a source of numerous under-studied psychoactive compounds, understanding the psychological and physiological effects of Cannabis is essential. The National Institute on Drug Abuse (NIDA) is designated as the sole legal producer of Cannabis for use in US research studies. We sought to compare the chemical profiles of Cannabis varieties that are available to consumers in states that have state-legalized use versus what is available to researchers interested in studying the plant and its effects. Our results demonstrate that the federally produced Cannabis has significantly less variety and lower concentrations of cannabinoids. Current research, which has focused on material that is far less diverse and less potent than that used by the public, limits our understanding of the plants chemical, biological, psychological, medical, and pharmacological properties. Investigation is urgently needed on the diverse forms of Cannabis used by the public in state-legal markets.

plant biology↗