Biology subjects

Cai, Q.

Publications and source records attributed to Cai, Q..

68 records · Page 4Linked to original sources

bioRxiv2022

Optical Modulation of Blood-Brain-Tumor Barrier Permeability Enhances Drug Delivery in Diverse Preclinical Glioblastoma Models

Glioblastoma multiforme (GBM) is the most prevalent malignant tumor in the central nervous system. It has diverse phenotypes, including diffuse single-cell infiltration in which the tumor cells co-opt the normal microvasculature, and the neovascularization of an expanding tumor mass. The blood-brain-tumor barrier (BBTB) is a significant obstacle to GBM treatment and restricts entry of most FDA-approved effective oncology drugs. Herein, we report that picosecond laser excitation of vascular-targeted plasmonic gold nanoparticles (AuNPs) can non-invasively and reversibly modulate the BBTB permeability (optoBBTB). OptoBBTB enhances the delivery of paclitaxel (Taxol) in two genetically engineered glioma models (GEMM) that span the spectrum of GBM phenotypes. OptoBBTB followed by Taxol delivery effectively suppresses tumor growth and prolongs the survival time of both GEMM. Moreover, our results raise the possibility that paclitaxel, which is amongst the most widely used oncology drugs because of its proven efficacy but has been abandoned for GBM following its failure to efficacy in early phase clinical trials due to poor blood-brain barrier (BBB) penetration, could now be reconsidered in combination with strategies to increase BBB permeability. In summary, optoBBTB is a novel and effective approach to increase the delivery of therapeutics with limited BBB permeability to treat neoplastic and non-neoplastic brain diseases.

bioengineering↗

bioRxiv2022

Calcium-Mediated Modulation of Blood-Brain Barrier Permeability by Laser Stimulation of Endothelial-Targeted Nanoparticles

The blood-brain barrier (BBB) maintains an optimal environment for brain homeostasis but excludes most therapeutics from entering the brain. Strategies that can reversibly increase BBB permeability will be essential for treating brain diseases and is the focus of significant preclinical and translational interest. Recently, we reported that picosecond laser excitation of molecular-targeted gold nanoparticles (AuNPs) induced a graded and reversible increase in BBB permeability in vivo (OptoBBB). Here we investigate how to increase the targeting efficiency and how picosecond lase stimulation of AuNP leads to an increase in endothelial paracellular permeability. Our results suggest that targeting brain endothelial glycoproteins leads to >20-fold higher targeting efficiency compared with tight junction targeting. We report that OptoBBB is associated with a transient elevation of Ca2+ that propagates to adjacent endothelial cells after laser excitation and extends the region of BBB opening. The Ca2+ response involves both internal Ca2+ depletion and Ca2+ influx. Furthermore, we demonstrate that the involvement of actin polymerization and Ca2+-dependent phosphorylation of ERK1/2 lead to cytoskeletal activation, increasing paracellular permeability. Taken together, we provide mechanistic insight into how excitation of endothelial targeted AuNPs leads to an increase in BBB permeability. These insights will be critical for guiding the future developments of this technology for brain disease treatment.

bioengineering↗

bioRxiv2022

Minimally invasive delivery of peptides to the spinal cord for behavior modulation

The blood-spinal cord barrier (BSCB) tightly regulates molecular transport from the blood to the spinal cord. Herein, we present a novel approach for transient modulation of BSCB permeability and localized delivery of peptides into the spinal cord for behavior modulation with high spatial resolution. This approach utilizes optical stimulation of vasculature-targeted nanoparticles and allows delivery of BSCB-nonpermeable molecules into the spinal cord without significant glial activation or impact on animal locomotor behavior. We demonstrate minimally invasive light delivery into the spinal cord using an optical fiber and BSCB permeability modulation in the lumbar region. Our method of BSCB modulation allows delivery of bombesin, a centrally-acting and itch-inducing peptide, into the spinal cord and induces a rapid and transient increase in itching behaviors in mice. This minimally invasive approach enables behavior modulation without genetic modifications and is promising for delivering a wide range of biologics into the spinal cord for behavior modulation and potentially therapy. Significance StatementSpinal cord diseases and disorders are common and cause significant disability, including chronic pain, paralysis, cognitive impairment, and mortality. The blood-spinal cord barrier is a considerable challenge for delivery by systemic therapeutic administration. We developed an optical approach for effectively and safely delivering molecules to the spinal cord to overcome this barrier. The fiberoptic method is minimally invasive and overcomes challenges that previous technologies face, including the complicated bone structure and standing waves that complicate BSCB opening using ultrasound. Optical stimulation offers unprecedented spatial resolution for the precise delivery in intricate spinal cord structures. Significantly, our approach modulates animal behavior (i.e., itch) without genetic modifications and demonstrates the potential for delivery of biologics such as peptides into the spinal cord.

neuroscience↗

bioRxiv2021

Methodological guidelines for isolation and purification of plant extracellular vesicles

Plant extracellular vesicles (EVs) have become the focus of rising interest due to their important roles in the cross-kingdom trafficking of molecules from hosts to interacting microbes to modulate pathogen virulence. However, the isolation of pure intact EVs from plants still represents a considerable challenge. Currently, plant EVs have been isolated from apoplastic washing fluid (AWF) using a variety of methods. Here, we compare two published methods used for isolating plant EVs, and provide a detailed recommended method for AWF collection from Arabidopsis thaliana, followed by EV isolation via differential ultracentrifugation. To further separate and purify specific subclasses of EV from heterogeneous vesicles, sucrose or iodixanol density-based separation and immunoaffinity capture are then utilized. We found that immunoaffinity capture provides a significant advantage for specific EV isolation when suitable specific EV biomarkers and their corresponding antibodies are available. Overall, this study guides the selection and optimization of EV isolation methods for desired downstream applications.

plant biology↗

bioRxiv2021

Human colorectal pre-cancer atlas identifies distinct molecular programs underlying two major subclasses of pre-malignant tumors

Most colorectal cancers (CRCs) develop from either adenomas (ADs) or sessile serrated lesions (SSLs). The origins and molecular landscapes of these histologically distinct pre-cancerous polyps remain incompletely understood. Here, we present an atlas at single-cell resolution of sporadic conventional tubular/tubulovillous ADs, SSLs, hyperplastic polyps (HPs), microsatellite stable (MSS) and unstable (MSI-H) CRC, and normal colonic mucosa. Using single-cell transcriptomics and multiplex imaging, we studied 69 datasets from 33 participants. We also examined separate sets of 66 and 274 polyps for RNA and targeted gene sequencing, respectively. We performed multiplex imaging on a tissue microarray of 14 ADs and 15 CRCs, and we integrated pre-cancer polyp data with published single-cell and The Cancer Genome Atlas (TCGA) bulk CRC data to establish potential polyp-cancer relationships. Striking differences were observed between ADs and SSLs that extended to MSS and MSI-H CRCs, respectively, reflecting their distinct origins and trajectories. ADs arose from WNT pathway dysregulation in stem cells, which aberrantly expanded and expressed a Hippo and ASCL2 regenerative program. In marked contrast, SSLs were depleted of stem cell-like populations and instead exhibited a program of gastric metaplasia in the setting of elevated cytotoxic inflammation. Using subtype-specific gene regulatory networks and shared genetic variant analysis, we implicated serrated polyps, including some HPs conventionally considered benign, as arising from a metaplastic program in committed absorptive cells. ADs and SSLs displayed distinct patterns of immune cell infiltration that may influence their natural history. Our multi-omic atlas provides novel insights into the malignant potential of colorectal polyps and serves as a framework for precision surveillance and prevention of sporadic CRC.

cancer biology↗

bioRxiv2020

CaMKII activation triggers persistent formation and segregation of postsynaptic liquid phase

Transient information input to brain leads to persistent changes in synaptic circuit, thereby forming memory engrams. Synapse undergoes coordinated functional and structural changes during this process but how such changes are achieved by its component molecules still largely remain enigmatic. We found that activated CaMKII, the central player of synaptic plasticity, undergoes liquid-liquid phase separation (LLPS) with NMDAR subunit GluN2B. Due to CaMKII autophosphorylation, the condensate stably persists even after Ca2+ is removed. The selective binding of activated CaMKII with GluN2B co-segregates AMPAR/neuroligin (NLGN) into a phase-in-phase assembly. Because postsynaptic NLGN clusters presynaptic neurexin and other active zone proteins thereby increasing the release probability of synaptic vesicles, this ensures efficient synaptic transmission. In this way, Ca2+-induced and persistent formation of LLPS by CaMKII serves as molecular basis of memory by functioning as an activity-dependent crosslinker for postsynaptic proteins and segregating trans-synaptic nanocolumns.

neuroscience↗

bioRxiv2020

Modulating the Blood-Brain Barrier by Light Stimulation of Molecular-Targeted Nanoparticles

The blood-brain barrier (BBB) tightly regulates the entry of molecules into the brain by tight junctions that seals the paracellular space and receptor-mediated transcytosis. It remains elusive to selectively modulate these mechanisms and to overcome BBB without significant neurotoxicity. Here we report that light stimulation of tight junction-targeted plasmonic nanoparticles selectively opens up the paracellular route to allow diffusion through the compromised tight junction and into the brain parenchyma. The BBB modulation does not impair vascular dynamics and associated neurovascular coupling, or cause significant neural injury. It further allows antibody and adeno-associated virus delivery into local brain regions. This novel method offers the first evidence of selectively modulating BBB tight junctions and opens new avenues for therapeutic interventions in the central nervous system. One Sentence SummaryGentle stimulation of molecular-targeted nanoparticles selectively opens up the paracellular pathway and allows macromolecules and gene therapy vectors into the brain.

neuroscience↗

bioRxiv2020

Oncogenic Activation of AKT by MAPK6

Mitogen-activated protein kinase 6 (MAPK6) is an atypical MAPK closely related to MAPK4. We recently reported that MAPK4 can promote cancer by activating the Protein Kinase B (PKB/AKT) pathway of cell growth and survival. Here we report that MAPK6 overexpression also activates AKT to induce oncogenic outcomes, including transforming "normal" human epithelial cells into anchorage-independent growth and enhancing cancer cell growth. Knockdown of MAPK6 inhibited cancer cell growth and xenograft growth, supporting the tumor-promoting activities of endogenous MAPK6. Unlike MAPK4, which binds AKT through its kinase domain and phosphorylates AKT at T308, MAPK6 interacts with AKT through its C34 region and the unique C-terminal tail and phosphorylates AKT at S473 independent of mTORC2, the major AKT S473 kinase. MAPK6 overexpression is associated with decreased overall survival and the survival of lung adenocarcinoma, mesothelioma, uveal melanoma, and breast cancer patients. We conclude that MAPK6 can promote cancer by activating AKT and that targeting MAPK6 may be effective in human cancers.

cancer biology↗

bioRxiv2020

The S1/S2 boundary of SARS-CoV-2 spike protein modulates cell entry pathways and transmission

The global spread of SARS-CoV-2 is posing major public health challenges. One unique feature of SARS-CoV-2 spike protein is the insertion of multi-basic residues at the S1/S2 subunit cleavage site, the function of which remains uncertain. We found that the virus with intact spike (Sfull) preferentially enters cells via fusion at the plasma membrane, whereas a clone (Sdel) with deletion disrupting the multi-basic S1/S2 site instead utilizes a less efficient endosomal entry pathway. This idea was supported by the identification of a suite of endosomal entry factors specific to Sdel virus by a genome-wide CRISPR-Cas9 screen. A panel of host factors regulating the surface expression of ACE2 was identified for both viruses. Using a hamster model, animal-to-animal transmission with the Sdel virus was almost completely abrogated, unlike with Sfull. These findings highlight the critical role of the S1/S2 boundary of the SARS-CoV-2 spike protein in modulating virus entry and transmission.

microbiology↗

bioRxiv2020

Electro-acupuncture alleviates METH withdrawal-induced spatial memory deficits by restoring astrocyte-derived glutamate uptake in dCA1

Methamphetamine (METH) is frequently abused drug and produces cognitive deficits. METH could induce hyper-glutamatergic state in the brain, which could partially explain METH-related cognitive deficits, but the synaptic etiology remains incompletely understood. To address this issue, we explored the role of dCA1 tripartite synapses and the potential therapeutic effects of electro-acupuncture (EA) in the development of METH withdrawal-induced spatial memory deficits in mice. We found that METH withdrawal weakened astrocytic capacity of glutamate (Glu) uptake, but failed to change Glu release from dCA3, which lead to hyper-glutamatergic excitotoxicity at dCA1 tripartite synapses. By restoring the astrocytic capacity of Glu uptake, EA treatments suppressed the hyper-glutamatergic state and normalized the excitability of postsynaptic neuron in dCA1, finally alleviated spatial memory deficits in METH withdrawal mice. These findings indicate that astrocyte at tripartite synapses might be a key target for developing therapeutic interventions against METH-associated cognitive disorders, and EA represent a promising non-invasive therapeutic strategy for the management of drugs-caused neurotoxicity.

neuroscience↗

bioRxiv2020

Untargeted Metabolomics Shows Alterations in Homocysteine, Lipids, and Fatty Acids Predicting Memory Decline in Healthy Middle-Aged Individuals

INTRODUCTIONSome aspects of memory start declining in the fifth decade which may be related to systemic metabolic changes. These changes have not been fully identified. This is the first Metabolome-Wide Association Study of the human plasma for the longitudinal change in memory in healthy adults. METHODSUltra-high resolution mass spectrometry with liquid chromatography was performed on 207 University employees plasma. RESULTSFrom 10,201 measured metabolic features, 558 differed between those experiencing change vs no change in memory (False Discovery Rate, FDR< 0.2). Differentially abundant metabolites were observed in lipid and fatty acid metabolism pathways: glycerophospholipid (p=0.0003), fatty acid (p=0.0003) and linoleate (p=0.0003) pathways. Within these pathways, higher homocysteine (OR for memory decline=1.09, FDR=0.19) and lower arachidonic acid (OR=0.97, FDR=0.19), sterol (OR=0.92, FDR=0.02), acetylcholine (OR=0.78, FDR=0.19), carnitine (OR=0.75, FDR=0.19) and linoleic acid (OR=0.74, FDR=0.19) were associated memory decline. DISCUSSIONAltered systemic lipid and fatty acid are linked with early memory decline in middle-aged individuals.

neuroscience↗

bioRxiv2019

How do we segment text? Two-stage chunking operation in reading

Chunking in language comprehension is a process that segments continuous linguistic input into smaller chunks that are in readers mental lexicon. Effective chunking during reading facilitates disambiguation and enhances efficiency for comprehension. However, the mechanisms of chunking remain elusive, especially in reading given that information arrives simultaneously yet the written systems may not have explicit cues for labeling boundaries such as Chinese. What are the mechanisms of chunking operation that mediates the reading of the text that normally contains hierarchical information? We investigated this question by manipulating the lexical status of the chunks at distinct levels of grain-size in four-character Chinese strings, including the two-character local chunk and four-character global chunk. Participants were asked to make lexical decision on these strings in a behavioral experiment, followed by a passive reading task when their electroencephalography (EEG) were recorded. The behavioral results showed that the lexical decision time of lexicalized two-character local chunks was influenced by the lexical status of four-character global chunk, but not vice versa, which indicated that the processing of global chunks possessed priority over the local chunks. The EEG results revealed that familiar lexical chunks were detected simultaneously at both levels and further processed in a different temporal order -- the onset of lexical access for the global chunks was earlier than that of local chunks. These consistent behavioral and EEG results suggest that chunking in reading occurs at multiple levels via a two-stage operation -- simultaneous detection and global-first recognition.\n\nSignificance StatementThe learners of a new language often read word by word. But why can proficient readers read multiple words at a time? The current study investigates how we efficiently segment a complicate text into smaller pieces and how we process these pieces. Participants read Chinese strings with different structures while their key-press responses and brain EEG signals were recorded. We found that texts were quickly (about 100 ms from their occurrences) segmented to varied sizes of pieces, and larger pieces were then processed earlier than small pieces. Our results suggest that readers can use existing knowledge to efficiently segment and process written information.

animal behavior and cognition↗

bioRxiv2019

Structural complementarity facilitates E7820-mediated degradation of RBM39 by DCAF15

The investigational drugs E7820, indisulam and tasisulam (aryl-sulfonamides) promote the degradation of the splicing factor RBM39 in a proteasome-dependent mechanism. While the activity critically depends on the Cullin RING ligase substrate receptor DCAF15, the molecular details remain elusive. Here we present the cryo-EM structure of the DDB1-DCAF15-DDA1 core ligase complex bound to RBM39 and E7820 at 4.4 [A] resolution, together with crystal structures of engineered subcomplexes. We show that DCAF15 adopts a novel fold stabilized by DDA1, and that extensive protein-protein contacts between the ligase and substrate mitigate low affinity interactions between aryl-sulfonamides and DCAF15. Our data demonstrates how aryl-sulfonamides neo-functionalize a shallow, non-conserved pocket on DCAF15 to selectively bind and degrade RBM39 and the closely related splicing factor RBM23 without the requirement for a high affinity ligand, which has broad implications for the de novo discovery of molecular glue degraders.

biochemistry↗

bioRxiv2019

Analysis of the Mutant Selection Window and Killing of Mycoplasma hyopneumoniae for Doxycycline, Tylosin, Danofloxacin, Tiamulin, and Valnemulin

Mycoplasma hyopneumoniae is the major pathogenic microorganism causing enzootic pneumonia in pigs. With increasing resistance of M. hyopneumoniae to conventional antibiotics, treatment is becoming complicated. Herein, we investigated the mutant selection window (MSW) of doxycycline, tylosin, danofloxacin, tiamulin, and valnemulin for treating M. hyopneumoniae strain (ATCC 25934) to determine the likelihood of promoting resistance with continued use of these antibiotics. Minimum inhibitory concentration (MIC) values against M. hyopneumoniae were determined for each antimicrobial agent and ranged from 105 colony-forming units (CFU)/mL to 109 CFU/mL based on microdilution broth and agar dilution methods. The minimal concentration inhibiting colony formation by 99% (MIC99) and the mutant prevention concentration (MPC) were determined by the agar dilution method with three inoculum sizes. Antimicrobial killing was determined based on MIC99 and MPC values for all five agents. MIC values ranged from 0.001 to 0.25 g/mL based on the microdilution broth method, and from 0.008 to 1.0 g/mL based on the agar dilution method. MPC values ranged from 0.0016 to 10.24 g/mL. MPC/MIC99 values were ordered tylosin >doxycycline >danofloxacin >tiamulin >valnemulin. MPC achieved better bactericidal action than MIC99. Based on pharmacodynamic analyses, danofloxacin, tylosin, and doxycycline are more likely to select resistant mutants than tiamulin and valnemulin.

pharmacology and toxicology↗