Biology subjects

Su, X.

Publications and source records attributed to Su, X..

At least 55 records · Page 3Linked to original sources

bioRxiv2025

A trade-off mechanism underpins the evolution of a young two-gene sex-determining system in plants

Sexual systems in animals and plants are remarkably diverse, with dioecy having evolved independently in numerous lineages. In plants, dioecy often evolved more recently than in the best-studied animal systems, making plants especially important for understanding how separate sexes evolved independently from functionally hermaphrodite ancestors. Despite long-standing theories of developmental trade-offs in sex allocation, the underlying genetic mechanisms remain elusive. Here, we show that the XY sex determination system in the dioecious plant species Eurycorymbus cavaleriei in Sapindaceae involves two Y-linked mutations that act jointly within the developmental male-female trade-off: YUN{Delta}, a truncated allele that lowers the dosage of the D-class MADS-box gene YUN, and SUNMAO, a novel sRNA locus that silences the X-linked SUN allele. In females, SUN stabilizes the HD-ZIP transcription factor KUN, which is a known sex determinant in another dioecious plant, thereby promoting femaleness by increasing YUN expression; loss of SUN expression, together with the effect of YUN{Delta}, shifts development toward males. Two interlocking regulatory loops in this "SKY" module (SUN-KUN-YUN) fine-tunes YUN dosage. This dioecious system in E. cavaleriei likely evolved by sequential mutations in genes acting in the predicted male-female trade-off system, with their close linkage reflecting a translocation, and later recombination-suppressing inversions.

plant biology↗

bioRxiv2025

Optimized large-scale longitudinal biorepository of gastroesophageal adenocarcinoma patient-derived organoids: High-fidelity models for personalized treatment to overcome resistance.

A major limitation in studying gastroesophageal adenocarcinoma (GEA) has been the lack of reliable models that represent the diseases complexity. We present lessons learned from a comprehensive large-scale biobanking effort combining traditional sample collection with several in vitro models including 3-dimensional patient-derived organoids (PDOs), 2-dimensional cancer-associated fibroblasts (CAFs), tumor-infiltrating lymphocytes (TILs) and/or in vivo xenografts. This initiative started in 2018, integrating multiple advanced ex-vivo models such as PDOs, patient-derived xenografts (PDXs) and organoids (PDXOs). This unique resource now includes tumor avatars from over 380 consented patients, making it the largest living GEA biobank in the world. We achieved > 90% success rate in creating per-patient models, including 227 tumor-derived and 203 neighboring normal PDOs. These organoids accurately mirror key features of the original tumors, such as their histology (e.g. microsatellite instability), mutations, and drug response, across treatment points. Notably, PDOs can predict individual patient responses to chemotherapy within five weeks, underscoring their clinical relevance. Furthermore, high-throughput drug screening on PDO subsets generates personalized chemosensitivity profiles for 22 drugs. Through a process of continued refinement of culture techniques and tumor sampling approach, our large-scale comprehensive collection of GEA avatars represents a unique and valuable preclinical experimental resource for precision oncology. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=76 SRC="FIGDIR/small/663874v1_ufig1.gif" ALT="Figure 1"> View larger version (28K): org.highwire.dtl.DTLVardef@f8a032org.highwire.dtl.DTLVardef@dd6fa3org.highwire.dtl.DTLVardef@1cc558corg.highwire.dtl.DTLVardef@492a5_HPS_FORMAT_FIGEXP M_FIG Schematic depiction of GEA live-banking workflow C_FIG

cancer biology↗

bioRxiv2025

T cell protrusions enable fast, localised initiation of CAR signalling

Actin-rich protrusions densely cover the surface of T cells and are well characterised for their role in cell migration. However, recent studies have uncovered their role in antigen surveillance and immune signalling initiation. To investigate how membrane protrusions initiate and contribute to signalling, from the first cell-cell contact to immunological synapse formation, we performed dynamic imaging experiments of endogenously tagged signalling proteins in T cells. To quantitatively capture the early dynamics of cell-cell interactions, we employed HER2-CAR-expressing T cells targeting HER2+breast cancer cells. By harnessing live-cell imaging and super-resolution stimulated emission depletion (STED) microscopy we were able to capture topological membrane changes and their correlation with mesoscale protein rearrangements over time. Our findings indicate that, prior to activation, key molecular players in T cell activation, including the kinase Lck, the phosphatase CD45 and the adaptor LAT, as well as the exogenously expressed CAR, lack any enrichment in actin-rich protrusions. However, upon initial contact of the T cell with the target cell, a dynamic and fast rearrangement of the surface receptors, phosphatases, and kinases occurs within the protrusions, ensuring a rapid and effective initiation of the immune signalling cascade. The rapid clustering of the HER2-CAR occurs preferentially within protrusions rather than flat membrane regions and is accompanied by enhanced recruitment of the kinase ZAP-70 and LAT. While the localisation of the kinase Lck remained unchanged, protrusion-cell contacts trigger a pronounced exclusion of the phosphatase CD45, an effect observed both with and without the cytosolic signalling domain of the CAR. Overall, the signalling machinery rearranged more rapidly and efficiently at contacts mediated by protrusive structures compared to non-protrusive regions. Together, our data provide a quantitative framework illustrating how signalling proteins are dynamically reorganised to facilitate CAR-mediated activation within these specialised structures.

cell biology↗

bioRxiv2025

Inclusion of the ζ-chain drives phosphotyrosine signalling in CD19-CAR T cells

Although chimeric antigen receptor (CAR) T cell therapy has revolutionised individualised cancer therapies for relapsed/refractory lymphomas, signalling mechanisms underlying CAR T activation remain incompletely understood, especially among the three generations of CAR T exploiting different signalling domains. Here, using Jurkat T cell as a model, we investigate how costimulation influences tyrosine phosphorylation cascades using LC-MS/MS based phosphotyrosine (pY) proteomics and CD69 expression in the presence of small molecule inhibitors of key TCR signalling regulators. We find that including the {zeta}-chain in first ({zeta}-CAR), second (28{zeta}-CAR and BB{zeta}-CAR), and third (28BB{zeta}-CAR) generation CARs largely determines pY signalling, irrespective of costimulation. Further, we show that the phosphatase activity of PTPN22 and SHP-1 are largely negligible for activation of CARs, but indiscriminate inhibition of phosphatases using Pervanadate (PV) selectively activates BB{zeta}-CARs without antigen encounter. Finally, we find that selective, partial inhibition of Itk using Soquelitinib reduces basal CD69 expression in Jurkat CAR T cells while maintaining their ability to activate in response to antigen. Our data suggest that the {zeta}-chain determines the pY signalling profile of CD19-CAR Jurkat T cells and that Itk may drive antigen-independent CD19-CAR activation.

cancer biology↗

bioRxiv2025

Optimizing Metagenome Analysis for Early Detection of Colorectal Cancer: Benchmarking Bioinformatics Approaches and Advancing Cross-Cohort Prediction

Colorectal cancer (CRC) continues to be a major global public health challenge. Extensive research has underscored the critical role of the gut microbiome for diagnostics of CRC. However, early-stage prediction of CRC, particularly at the precancerous adenomas (ADA) stage, remains challenging due to the instability of microbial features across cohorts. In this study, we conducted a systematic analysis of 2,053 gut metagenomes from 14 globally-sampled public cohorts and a newly recruited cohort. Despite substantial regional and cohort-level heterogeneity in microbiome composition, we elucidated that the consistent dynamic patterns of microbial signatures are the fundamental for CRC detection. These patterns enabled robust performance in both inter-cohort and independent validations using an optimized bioinformatics framework. In contrast, such basis was lacking in ADA-associated microbial markers, limiting the generalizability of early detection models. To address this, we developed an instance-based transfer learning approach, Meta-iTL, which effectively leveraged knowledge from existing datasets to detect CRC risk at the ADA stage in the newly recruited cohort. Thus, Meta-iTL overcomes challenges posed by cohort-specific variability and limited data availability, advances the application of non-invasive approaches for the early screening and prevention of CRC.

bioinformatics↗

bioRxiv2025

Autophagy Suppresses CCL2 to Preserve Appetite and Prevent Lethal Cachexia

Macroautophagy (autophagy hereafter) captures intracellular components and delivers them to lysosomes for degradation and recycling1. In adult mice, autophagy sustains metabolism to prevent wasting by cachexia and to survive fasting, and also suppresses inflammation, liver steatosis, neurodegeneration, and lethality2,3. Defects in autophagy contribute to metabolic, inflammatory and degenerative diseases, however, the specific mechanisms involved were unclear 4. Here we profiled metabolism and inflammation in adult mice with conditional, whole-body deficiency in an essential autophagy gene and found that autophagy deficiency altered fuel usage, and reduced ambulatory activity, energy expenditure, and food intake, and elevated circulating GDF15, CXCL10, and CCL2. While deletion of Gdf15 or Cxcl10 provided no or mild benefit, deletion of Ccl2 restored food intake, suppressed cachexia and rescued lethality of autophagy-deficient mice. To test if appetite suppression by CCL2 was responsible for lethal cachexia we performed single nucleus RNA sequencing of the hypothalamus, the center of appetite control in the brain. Notably, we found that autophagy deficiency was specifically toxic to PMCH and HCRT neurons that produce orexigenic neuropeptides that promote food intake, which was rescued by deficiency in CCL2. Finally, the restoration of food intake via leptin deficiency prevented lethal cachexia in autophagy-deficient mice. Our findings demonstrate a novel mechanism where autophagy prevents induction of a cachexia factor, CCL2, which damages neurons that maintain appetite, the destruction of which may be central to degenerative wasting conditions. Key points of paper1) Autophagy-deficient mice have reduced food intake, systemic inflammation, and cachexia 2) CCL2, but not GDF15 or CXCL10, induces lethal cachexia caused by autophagy defect 3) Autophagy-deficient mice have CCL2-dependent destruction of appetite-promoting neurons in the hypothalamus 4) Leptin deficiency restores appetite and rescues lethal cachexia in autophagy-deficient mice 5) Autophagy-deficient mice die from cachexia mediated by appetite loss 6) Degenerative conditions due to impaired autophagy are caused by the inflammatory response to the damage 7) Targeting CCL2 may be a viable approach to prevent degenerative wasting disorders

molecular biology↗

bioRxiv2025

Disruption of Mitochondrial Dynamics and Stasis Leads to Liver Injury and Tumorigenesis

Background & AimsMitochondrial dysfunction has been implicated in aging and various cancer development. As highly dynamic organelles, mitochondria constantly undergo fission, mediated by dynamin-related protein 1 (DRP1, gene name Dnm1l), and fusion, regulated by mitofusin 1 (MFN1), MFN2, and optic atrophy 1 (OPA1). However, whether and how dysregulation of mitochondria dynamics would be involved in liver pathogenesis and tumorigenesis is unknown. MethodsDnm1l Flox/Flox (Dnm1lF/F), Mfn1F/F and Mfn2F/F mice were crossed with albumin-Cre mice to generate liver-specific Dnm1l knockout (L-Dnm1l KO), L-Mfn1 KO, L-Mfn2 KO, L-Mfn1, Mfn2 double KO (DKO), and L-Mfn1, Mfn2, Dnm1l triple KO (TKO) mice. These mice were housed for various periods up to 18 months. Some mice also received hydrodynamic tail vein injections of a Sleeping Beauty transposon-transposase plasmid system with c-MYC and YAP. Blood and liver tissues were harvested for biochemical and histological analysis. ResultsL-Dnm1l KO mice had elevated serum alanine aminotransferase levels and increased hepatic fibrosis as early as two months of age. By 12 to 18 months, male L-Dnm1l KO mice developed spontaneous liver tumors, primarily hepatocellular adenomas. While female L-Dnm1l KO mice also developed liver tumors, their incidence was much lower. In contrast, neither L-Mfn1 KO nor L-Mfn2 KO mice had notable liver injury or tumorigenesis. However, a small portion of DKO mice developed tumors at 15-18 month-old. Increased DNA damage, senescence and compensatory proliferation were observed in L-Dnm1l KO mice but were less evident in L-Mfn1 KO, L-Mfn2 KO or DKO mice, indicating that mitochondrial fission is more important to maintain hepatocyte homeostasis and prevent liver tumorigenesis. Interestingly, further deletion of Mfn1 and Mfn2 in L-Dnm1l KO mice markedly abolished liver injury, fibrosis, and both spontaneous and oncogene-induced tumorigenesis. RNA sequencing and metabolomics analysis revealed significant activation of the cGAS-STING-interferon pathway and alterations in the tumor microenvironment pathways, alongside increased pyrimidine synthesis and metabolism in the livers of L-Dnm1l KO mice. Notably, the changes in gene expression and pyrimidine metabolism were considerably corrected in the TKO mice. ConclusionsMitochondrial dynamics and stability are essential for maintaining hepatic mitochondrial homeostasis and hepatocyte functions. Loss of hepatic DRP1 promotes liver tumorigenesis by increasing pyrimidine metabolism and activating the cGAS-STING-mediated innate immune response.

cell biology↗

bioRxiv2025

CandyCollect Open to Closed (O2C) Microfluidic System for Rapid and User-Centric Detection of Group A Streptococcus

We created CandyCollect, a lollipop-inspired, child-friendly saliva sampling device that provides enhanced comfort compared to common throat and mouth swabs. The device has an open microchannel and a functionalized surface that effectively captures and stores the saliva and pathogens. We recently demonstrated the ability to combine the CandyCollect with rapid antigen detection tests (RADTs) for fast and accessible detection of group A streptococcus (GAS). However, the current procedure necessitates manual steps to elute and transfer captured antigens from the lollipop to RADTs, which relies on the user to follow complex instructions, increasing the likelihood of error. In this work, we developed the CandyCollect Open to Closed (O2C) microfluidic system to automate antigen elution and streamline detection with RADTs. The O2C system securely seals the open microchannels of the CandyCollect device to create a continuous closed channel for seamless delivery of elution reagents to release antigens at the press of a button for subsequent lateral flow detection. Our system leverages and combines the unique benefits of both open channel and closed channel microfluidics into one platform, further enhancing the potential of both methods. We performed experiments with GAS bacteria spiked into saliva and compared the manual and O2C elution methods. Both the manual and O2C methods showed clear test lines on the RADT strips at clinically relevant GAS concentrations (between 5 x105 and 109 CFU/mL). The O2C provided comparable or better results than the manual procedure in a more convenient form factor. The O2C platform has the potential to enable user-friendly screening for respiratory pathogens by minimally trained users in decentralized settings.

bioengineering↗

bioRxiv2025

Gut microbiota phospholipids regulate intestinal gene expression and can counteract the effects of antibiotic treatment

The gut microbiome influences immune and metabolic homeostasis. Our research using non-obese diabetic (NOD) mice revealed that early-life antibiotic exposure remodels the gut microbiome affecting metabolism and accelerating type 1 diabetes (T1D) incidence, with cecal material transplant (CMT) mitigating the damage. Now examining murine intestinal lipidomic profiles, we identified 747 compounds. Comparing the lipidomic profiles of cecal contents of conventional and germ-free mice and their diets, we identified 87 microbially-produced lipids reduced by antibiotic exposure but CMT-restored. Parallel analysis of human fecal lipid profiles after azithromycin-exposure showed significant alterations with substantial overlap with mice. In vitro co-culture with mouse macrophages or small intestinal epithelial cells and human colonic epithelial cells identified phospholipids that repress inflammation through the NF{kappa}B pathway. Oral administration of these phospholipids to antibiotic-treated NOD mice reduced expression of ileal genes involved in early stages of T1D pathogenesis. These findings indicate potential therapeutic anti-inflammatory roles of microbially-produced lipids.

microbiology↗

bioRxiv2025

Neural circuits between nodose ganglion and pulmonary neuroendocrine cells regulate lung inflammatory responses

The lungs are organs exposed to the external environment, and the air we inhale contains various pathogens, such as endotoxins. The vagus nerve, which innervates the lungs, may play a role in detecting pathogens that invade the lungs. Through transcriptome analysis, tissue clearance imaging, electrical excitability recording, and gene- and cell-specific knockout experiments, we found that vagus nerve endings innervate pulmonary neuroendocrine cells (PNECs). These nerve endings sense bacterial endotoxins via pain receptors (TRPA1) rather than toll-like receptors (TLR4), eliciting electrical excitation and enhancing the production of neuropeptides (CGRP) in the nodose ganglia. In turn, CGRP released by sensory neurons from the nodose ganglia promotes both neuropeptide production and the proliferation of PNECs, thereby amplifying endotoxin-induced lung inflammatory responses. This reveals that the neural circuits between the nodose ganglion and PNECs play a critical role in regulating lung inflammatory responses.

neuroscience↗

bioRxiv2024

CSF1R-CAR T cells induce CSF1R signalling and promote cancer cell growth

Chimeric antigen receptor (CAR) T cells have transformed the landscape of cancer therapy and demonstrate unprecedented success in treating relapsed/refractory blood cancers. The mechanism underlaying the interactions and responses of CAR T cells and their targets remain incompletely understood. Previous studies focus on the activation of CAR T cells and attempt to optimise CAR design to increase efficacy, meanwhile ignoring tumours and their responses to CAR ligation. Here, we evaluate the signalling capacity of a second generation CSF1-tageted CSF1R CAR compared with a scFv-targeted CD19-CAR using a SILAC co- culture approach coupled with phosphotyrosine (pY) enrichment and LC-MS/MS. We show that ligation of CSF1R-expressing THP1 cells with CSF1R-CAR T cells induces CSF1R-like signalling in THP1 cells, whereas no target cell signalling response is observed after CD19- CAR/Raji B cell ligation. Using small molecule inhibitors of Lck, actin polymerisation, and CSF1R, we find that CAR-induced CSF1R signalling in THP1 cells depends exclusively on CSF1R kinase activity with no participation from T cell activation. Consistently, CSF1R- CAR T cells promote THP1 growth at low effector-to-target (E:T) ratios but prevent THP1 growth at high E:T ratios. Our data provide evidence for an unintended consequence of CARs; CAR-induced signalling in cancer cells. These data may have broad implications for the choice of CAR antigen for optimal clinical efficacy. One Sentence Summary: CSF1R-CAR activates intracellular signalling cascades in THP1 cells, which promote THP1 cell growth.

cancer biology↗

bioRxiv2024

Hyperactive PLCG1 drives non-canonical signaling to promote cell survival

One of the long-standing questions in cell signaling field to identify and characterize key signaling nodes out of a complex network. Phospholipase C{gamma}1 (PLCG1) was identified as the most frequently mutated gene in adult T-cell leukemia/lymphoma, suggesting a critical function of PLCG1 in driving T cell activation. However, it remains unclear how these mutations regulate T cell physiology and pathology. Here we investigated three common leukemia/lymphoma associated mutations (R48W, S345F, and D1165H). We discovered that these mutations induced hyperactive T cell signaling and caused pro-survival phenotypes. PLCG1 mutants enhanced LAT condensation, calcium influx, and ERK activation. They promoted T cell proliferation, induced cell aggregation, and rendered resistance to vorinostat, an FDA-approved drug for cutaneous T-cell lymphoma. The resistance to vorinostat depended on ERK signaling and can be reversed with an ERK inhibitor. Mechanistically, alpha smooth muscle actin, which was specifically induced by PLCG1 mutants, directly bound PLCG1 to promote its activation. Together, these results demonstrated that hyperactive PLCG1 promoted T cell survival and drug resistance through inducing non-canonical signaling.

cell biology↗

bioRxiv2024

TFE3 fusion proteins drive oxidative metabolism, ferroptosis resistance and general RNA synthesis in translocation renal cell carcinoma

The oncogenic mechanisms by which TFE3 fusion proteins drive translocation renal cell carcinoma (tRCC) are poorly characterised. Here, we integrated loss and gain of function experiments with multi-omics analyses in tRCC cell lines and patient tumors. High nuclear accumulation of NONO-TFE3 or PRCC-TFE3 fusion proteins promotes their broad binding across the genome at H3K27ac-marked active chromatin, engaging a core set of M/E-box-containing regulatory elements to activate specific gene expression programs as well as promiscuous binding to active promoters to stimulate mRNA synthesis. Within the core program, TFE3 fusions directly regulate genes involved in ferroptosis resistance and oxidative phosphorylation metabolism (OxPhos) increasing functional OxPhos levels. Consequently, human tRCC tumors display high OxPhos scores that persist during their epithelial to mesenchymal transition (EMT). We further show that tRCC tumour aggressiveness is related to their EMT and their associated enrichment in myofibroblast cancer-associated fibroblasts (myCAFs) that are both hallmarks of poor prognostic outcomes. We define tRCC as a novel metabolic subtype of renal cancer and provide unique insights into how broad genomic binding of TFE3 fusion proteins regulates OxPhos and ferroptosis resistance and more generally stimulates RNA synthesis. SynopsisDefining the gene expression programs regulated by TFE3 fusion proteins in translocation renal cell carcinoma. TFE3 fusion proteins promote expression of oxidative metabolism genes and oxidative metabolism in tRCC. TFE3 fusion proteins regulate glutathione metabolism and ferroptosis resistance in tRCC. TFE3 fusion proteins bind broadly at active promoters and stimulate RNA synthesis in tRCC. Epithelial-to-mesenchymal transition in tRCC is accompanied by enrichment in myofibroblastic cancer-associated-fibroblasts and poor patient outcome. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=187 SRC="FIGDIR/small/620047v2_ufig1.gif" ALT="Figure 1"> View larger version (37K): org.highwire.dtl.DTLVardef@b9dcb6org.highwire.dtl.DTLVardef@495f42org.highwire.dtl.DTLVardef@10d1770org.highwire.dtl.DTLVardef@7df40c_HPS_FORMAT_FIGEXP M_FIG C_FIG The paper explained. Problem.Translocation renal cell carcinoma (tRCC) is a rare subtype of kidney cancer characterised by genetic translocation events frequently involving transcription factor TFE3 or more rarely TFEB. While the resulting fusion proteins are considered as the oncogenic drivers, their mechanism of action remains poorly understood. Results.By integrative multi-omics analyses in tRCC cell lines and patient tumors together with loss and gain of function experiments, we found broad binding of TFE3-fusion proteins at active promoters and identified a core set of target genes involved in multiple pathways, including oxidative metabolism (OxPhos) and ferroptosis. Consequently, tRCC cell lines displayed higher functional OxPhos levels and patient tumours displayed elevated OxPhos scores and ferroptosis resistance gene expression. Analyses of tRCC patient transcriptome data further revealed that mesenchymal tRCC tumours are enriched in myofibroblastic cancer associated fibroblasts that are hallmarks of poor prognostic outcome. ImpactThis study advances understanding of the molecular mechanisms underlying oncogenic transformation by TFE3 fusion proteins by defining a core program of gene expression and key features of tumour cells and their microenvironment that negatively impact patient outcome. Our integrative multi-omics and functional analyses reveal how extensive genomic binding of TFE3 fusion proteins drives high levels of oxidative metabolism, ferroptosis resistance and general RNA synthesis.

cancer biology↗

bioRxiv2024

Mutations of schizophrenia risk gene SETD1A dysregulate synaptic function in human neurons

Schizophrenia (SCZ) is a complex neuropsychiatric disorder associated with both common risk variants of small effect sizes and rare risk variants of high penetrance. Rare protein truncating variants (PTVs) in SETD1A (SET Domain Containing 1A) show a strong association with SCZ; however, it remains largely unclear how rare PTVs in SETD1A contribute to the pathophysiology of SCZ. To understand the impact of SETD1A rare PTVs in human neurons, we CRISPR/Cas9-engineered five isogenic pairs of human induced pluripotent stem cells (iPSCs), with a recurrent heterozygous patient-specific PTV mutation c.4582-2delAG in two donor lines and a heterozygous frameshift mutation c.4596_4597insG (p. Leu1533fs) in three donor lines. These two mutations are predicted to cause a premature stop codon in exon 16 of SETD1A, leading to the loss of the conserved SET domain that is critical for its histone methyltransferase activity. We found that these presumably loss-of-function (LoF) mutations caused the SETD1A mRNAs to be degraded by nonsense-mediated decay (NMD), accompanied by a reduction of full-length SETD1A protein level in iPSCs. We then characterized the morphological, electrophysiological, and transcriptomic impacts of the SETD1A+/- LoF mutations in iPSC-derived human excitatory neurons induced by NGN2. We found that the SETD1A+/- exon-16 LoF mutations altered dendrite complexity, dysregulated synaptic transmission, and synaptic plasticity, likely by dysregulating genes involved in synaptic function. These results provide mechanistic insights into how SETD1A+/-exon-16 patient-specific LoF mutations affect neuron phenotypes that may be relevant to the pathophysiology of SCZ.

neuroscience↗

bioRxiv2024

CandyCollect: An Open-Microfluidic Device for the Direct Capture and Enumeration of Salivary-Extracellular Vesicles

Extracellular vesicles (EVs) are promising biomarkers for disease detection using a liquid biopsy approach, in which they are enriched and analyzed directly from biofluids. However, implementing EV biomarker technologies in the clinic remains limited by the need for practical and patient-centric biofluid collection methods that are compatible with downstream EV processing and analysis. While saliva offers a non-invasive source of EVs, its complexity and heterogeneity--cells, debris, and other non-EV proteins--can present hurdles when using traditional analytical platforms. Here, we present the CandyCollect, a lollipop-inspired sampling device with open microfluidic channels, as a patient-friendly approach for rapid salivary EV capture. CandyCollect simplifies sample preparation by effectively pre-concentrating EVs in oxygen-plasma treated open microfluidic channels. In this proof-of-principle study, we show that following a 3-5 minute-oral sampling period, EVs collected by the CandyCollect can be released with high purity within minutes and subsequently quantified and analyzed for cargo content. We observed consistent EV capture across repeated collections within individuals and expected variability across healthy participants. Additionally, single and pooled collections of EVs from a healthy participant resulted in a concordant protein profile. Overall, the CandyCollect is a new platform for rapid, non-invasive salivary EV collection and analysis for clinical diagnostics.

bioengineering↗

bioRxiv2024

ADENYLATE CYCLASE 3 MEDIATES CAROTID BODY ACTIVATION AND AUTONOMIC DYSFUNCTION IN A SLEEP APNEA MODEL

Patients with obstructive sleep apnea (OSA) experience chronic intermittent hypoxia (CIH). OSA patients and CIH-treated rodents exhibit autonomic dysfunction, characterized by overactive sympathetic nervous system and hypertension, mediated through hyperactive carotid body (CB) chemoreflex. Activation of olfactory receptor 78 (Olfr78) by hydrogen sulfide (H2S) is implicated in CB activation and autonomic responses to CIH, but the downstream signaling pathways remain unknown. Given that odorant receptor signaling is coupled to adenylyl cyclase 3 (Adcy3), we hypothesized that Adcy3-dependent cAMP contributes to CB and autonomic responses to CIH. Our findings show that CIH increases cAMP levels in the CB, a response absent in Adcy3, Cth, and Olfr78 null mice. CBs from Cth and Olfr78 mutant mice lacked persulfidation response to CIH, indicating that Adcy3 activation by CIH requires Olfr78 activation by H2S. CIH also enhanced glomus cell Ca2+ influx, an effect absent in Cnga2 and Adcy3 mutants, suggesting that CIH-induced cAMP mediates enhanced Ca2+ responses through cyclic nucleotide-gated channels. Furthermore, Adcy3 null mice did not exhibit neither CB activation nor autonomic dysfunction by CIH. These results demonstrate that Adcy3-dependent cAMP is a downstream signaling pathway to H2S/Olfr78, mediating CIH-induced CB activation and autonomic dysfunction.

physiology↗

bioRxiv2024

Architecture of the ATP-driven motor for protein import into chloroplasts

Thousands of nuclear-encoded proteins are transported into chloroplasts through the TOC-TIC translocon spanning the chloroplast envelope membranes. A motor complex pulls the translocated proteins out of the TOC-TIC complex into the chloroplast stroma by hydrolyzing ATP. The Orf2971-FtsHi complex was suggested to serve as the ATP-hydrolyzing motor in Chlamydomonas reinhardtii, but little is known about its architecture and assembly. Here, we report the 3.2-[A] resolution structure of the Chlamydomonas Orf2971-FtsHi complex. The 20-subunit complex spans the chloroplast inner envelope with two bulky modules protruding into the intermembrane space and stromal matrix. Six subunits form a hetero-hexamer potentially providing the pulling force through ATP hydrolysis. The remaining subunits, including potential enzymes/chaperones, likely facilitate the complex assembly and regulate its proper function. Our results provide the structural foundation for mechanistic understanding of chloroplast protein translocation.

biochemistry↗

bioRxiv2024

Microbial Weathering Analysis of Anshun Tunbao Artifacts

AbstractsCultural heritages are the crystallization of human technology, culture and embody the efforts of many craftsmen in ancient times. Wooden cultural heritages are affected by their own materials, and are very susceptible to microbial invasion under suitable temperature and humidity conditions. This project mainly studies the microbial weathering of the core wood carving masks and wooden ancient stage in Anshun Tunpu cultural heritage, and uses scanning electron microscopy, high-throughput sequencing and traditional culture methods to analyze the characteristics of their microbial communities, and finds that the bacteria represented by Pseudomonas, Paenibacillus and Stenotrophomonas, and the fungi represented by Cladosporium, Alternaria and Aspergillus, are the core microorganisms shared by indoor and outdoor cultural heritage. The dominant genera such as Pseudomonas, Stenotrophomonas, and Cladosporium showed lignocellulose deradation ability. By cultivating insect eggs extracted from sampled specimens and analyzing the correlation with surface microbiota, we verified the role of insect eggs as vectors in dispersing key microbial communities. We speculate that these insects are likely to be Anobiidae family. Furthermore, by comparing the microbial compositions under different climatic conditions, we validated the influence of temperature, humidity, vegetation diversity, and microbial intrinsic structures on microbial growth. Therefore, monitoring the surrounding environment is crucial in microbial weathering studies and cultural heritage preservation efforts. This study pioneered the investigation of microbial weathering aspects on unique heritage of the Tuenbao culture, emphasizing the importance of preserving distinctive ethnic cultures. Additionally, it presented a case study on the microbial weathering of wooden artifacts in karst landscape environments.

microbiology↗