Biology subjects

Zhang, C.

Publications and source records attributed to Zhang, C..

At least 343 records · Page 19Linked to original sources

bioRxiv2024

Structural Basis of GPCR-G Protein Pre-coupling and Activation: Insights from CCR1-Gi Complex

GPCR-mediated G protein activation cycle contains obligated step of the receptor-G protein assembly before G protein activation (pre-coupling state). However, transient nature of this pre-coupling state has prevented structural and mechanistic understanding of this essential step of G protein activation cycle. In this study, we discover that CCR1 has high level of pre-coupling state, which allows its rapid response to chemokines. Taking advantage of this observation, we uncover molecular mechanism of the pre-coupling state by solving the cryo-electron microscopy structure of the chemokine receptor CCR1 in complex with its cognate G protein (Gi) in a pre-coupled, inactivated state. This structure reveals that CCR1 adopts a conformation distinct from both its fully active and inactive states, with the G proteins 5 helix partially inserted into the receptors intracellular cavity. Notably, the C-terminal four residues of the G subunit are disordered in this pre-coupled state, contrasting with their well-defined -helical structure in the fully active complex. Functional assays demonstrate that while deletion of these four C-terminal G residues does not affect pre-coupling, it abolishes G protein activation upon agonist binding. This finding highlights the critical role of these residues in GPCR-mediated G protein activation, but not in initial recruitment. Furthermore, our studies indicate that the ability to form pre-coupled complexes is conserved among chemokine receptors, suggesting a common mechanism for rapid signal transduction in this GPCR subfamily. These results provide the first structural evidence for GPCR-G protein pre-coupling and offer molecular insights into the transition from inactive to active states. Our findings fill the long-missing gap in understanding GPCR-mediated G protein activated cycle.

biophysics↗

bioRxiv2024

Nitrate Promoting Hair Growth Through Enhancing Wnt/β-catenin and Downregulating TGF-β/Samd/BMP signaling pathway in C57BL/6 Mice

Nitrate found widely distributed in vegetables and fruits. It has been proved to have many physiological functions through nitrate-nitrite-NO pathway, such as attenuate oxidative stress, enhance the skeletal muscle and tone skin vascular. But the function of nitrate in regulating hair growth is unclear. Here, we evaluated potential roles of nitrate on hair growth and its mechanisms by in vivo models. Mice treated with 10mM nitrate supplementation significantly promoting hair growth, along with an increase in the number of hair follicles and thickness of dermis. We further demonstrated that Wnt3a and {beta}-catenin were highly expressed in the nitrate-treated groups, while the expression of TGF-{beta}1 was attenuated. Moreover, nitrate also increased the expression levels of growth factors (Fgf, Igf-1, and Vegf). Our data indicated that nitrate supplementation could effectively accelerate hair regrowth through activating the Wnt/{beta}-catenin and inhibiting TGF-{beta}1/Smad/BMP signaling pathway. Therefore, these findings provide support for a potential therapeutic role of nitrate in preventing and treating alopecia.

biochemistry↗

bioRxiv2024

Site-specific quantification of the in vivo UFMylome reveals myosin modification in ALS

UFMylation is a ubiquitin-like protein post-translational modification of Ubiquitin Fold Modifier 1 (UFM1) applied to substrate proteins. The UFMylation system is important for normal development and plays a critical role in a variety of cellular processes including regulating telomere length, stress responses and protein quality control. Here, we describe the development of an antibody-based enrichment approach to immunoprecipitate in vivo remnant UFMylated peptides and identification by liquid chromatography and tandem mass spectrometry (LC-MS/MS). We used this approach to identify >200 UFMylation sites from various mouse tissues revealing extensive modification in skeletal muscle. Furthermore, we show that UFMylation is increased in skeletal muscle biopsies from people living with Amyotrophic Lateral Sclerosis (plwALS). Quantification of UFMylation sites in these participant biopsies with multiplexed isotopic labeling and LC-MS/MS reveal prominent increases in myosin UFMylation. Finally, in silico modelling suggest UFMylation of myosin directly adjacent to the ATP-binding site may regulate stability and/or function. Our data suggest that although UFMylation is not as widespread as ubiquitylation, its in vivo status is more complex than previously thought.

biochemistry↗

bioRxiv2024

Omega-3 fatty acid normalizes postsynaptic density proteins via miRNAs regulation in hippocampus and prevents DEHP-induced impairment of learning and memory in mice

AbstractsDEHP is the most widely used plasticizer in many products. However, growing evidence has indicated that DEHP may induce neurotoxicity. DEHP exposure affects mircoRNAs (miRNAs) expression in brain. A growing body of evidence suggests that nutrients and other bioactive food components prevent neurotoxicity through regulation of miRNA expression. Due to the increasing concern about the risks of DEHP to human health, we explored the neuroprotective effect of Omega-3 fatty acid (Omega-3FA) on subchronic DEHP-induced neurotoxicity in mice, and the potential involved miRNAs and their targets in the protective action of Omega-3FA against DEHP-induced neurotoxicity. Omega-3FA protected against the DEHP-induced impairment of learning and memory and alleviated the thinning of postsynaptic density (PSD) thickness in hippocampal synapses. We observed that there are fourteen up or down regulated miRNAs associated PSD in DEHP exposure which were normalized by Omega-3FA treatment. Protein targets in PSD of these differentially expressed miRNAs were predicted. Furthermore, the expression levels of protein mGluR5, Homer1, and NMDAR2B were carried out via Western blot, for further verifying PSD associated miRNAs targets are involved in neuroprotection of Omega-3FA against DEHP. These findings suggested that Omega-3FA protected DEHP-induced impairment of learning and memory as well as synaptic structure alteration in the hippocampus by regulating the expression of PSD associated miRNAs and their targets. Thus, Omega-3FA should be included in diet to prevent or suppress neurotoxicity caused by continuous exposure to DEHP.

neuroscience↗

bioRxiv2024

Genomic diversity and underlying metabolic variations of the human gut microbiome between populations at single nucleotide resolution

BackgroundA comprehensive and representative reference database is crucial for accurate taxonomic and functional profiling of the human gut microbiome in population-level studies. However, with 70% of current microbial reference data derived from Europeans and the Americans, East Asia, especially China, remain underrepresented. MethodsWe constructed the human Gut Microbiome Reference (GMR), comprising 478,588 high-quality microbial genomes from Chinese (247,134) and non-Chinese (231,454) populations. Species-level clustering and protein annotations were performed to characterize microbial diversity and function. We further integrated novel genomes into taxonomic profiling database and validated the improvements using independent cohort data. ResultsThe GMR dataset spans 6,664 species, including 26.4% newly classified species, and encodes over 20 million unique proteins, with 47% lacking known functional annotations. Notably, we observed that 35.35% and 32.46% of species unique to Chinese and non-Chinese populations, respectively. For 2,145 species shared between populations, 74% of 304 species with balanced prevalence between populations exhibited population-specific phylogenetic stratification, involving health relevant functionalities such as antibiotic resistance. Integration of novel genomes into taxonomic improved population-level species profiling by up to 23% and uncovered replicable associations between novel species and host physiological traits. ConclusionsOur study largely expands the compositional and functional landscape of the human gut microbiome, providing a crucial resource for studying the role of gut microbiome for regional health disparities.

genomics↗

bioRxiv2024

A spatiotemporal atlas of human spermatogenesis based on single-cell transcriptomics and multiplex antibody imaging

Understanding how transcriptional programs are translated into functional protein landscapes within intact tissues remains a major challenge in biology. While single-cell RNA sequencing (scRNA-seq) has enabled high-resolution identification of cellular states, corresponding protein expression within its spatial context remains poorly resolved at scale. Here, we present a scalable framework that integrates scRNA-seq with multiplex immunohistochemistry (mIHC) and automated image analysis to achieve spatially resolved, single-cell-level protein mapping across human spermatogenesis. Using this approach, we quantified the expression of nearly 500 proteins across 12 discrete germ cell states within intact human testis tissue, generating a high-resolution spatiotemporal proteomic atlas. Comparative analysis of mRNA and protein expression revealed widespread temporal discordance, indicating that transcriptional state is not always predictive of protein abundance. Notably, we identify delayed translation of key regulators such as PIWIL4, whose protein expression peaks at later differentiation stages than its mRNA expression. Together, our results establish a generalizable strategy for proteome-wide spatial mapping of single-cell states and demonstrate the importance of integrating protein-level measurements to resolve cellular identity and function in complex tissues.

molecular biology↗

bioRxiv2024

IOP-induced blood-retinal barrier compromise contributes to RGC death in glaucoma

The integrity of the blood-retinal barrier (BRB) has been largely unexplored in glaucoma. We reveal that elevated intraocular pressure (IOP) partially compromises the BRB in two human-relevant inherited mouse models of glaucoma (DBA/2J and Lmx1bV265D). Experimentally increasing IOP in mouse eyes further confirms this. Notably, the compromise induces subtle leakage, happening without bleeding or detected endothelial cell junction disruption, and it precedes neurodegeneration. Leakage occurs from peripheral veins in the retinal ganglion cell layer with a concomitant loss of the transcytosis inhibitor MFSD2A. Importantly, stabilizing {beta}-catenin in retinal endothelial cells prevents both vascular leakage and neurodegeneration in the DBA/2J model. The occurrence of leakage in all 3 high IOP models indicates that BRB compromise may be a common, yet overlooked, mechanism in glaucoma. These findings suggest that IOP-induced BRB compromise plays a critical role in glaucoma, offering a new therapeutic target.

neuroscience↗

bioRxiv2024

Sugar-rich foods exacerbate antibiotic-induced microbiome injury

Intestinal microbiota composition is implicated in several diseases; understanding the factors that influence it are key to elucidating host-commensal interactions and to designing microbiome-targeted therapies. We quantified how diet influences microbiome dynamics in hospitalized patients. We recorded 9,419 meals consumed by 173 patients undergoing hematopoietic cell transplantation and profiled the microbiome in 1,009 longitudinally collected stool samples from 158 of them. Caloric intake was correlated with fecal microbiota diversity. Bayesian inference revealed associations between intake of sweets or sugars during antibiotic exposure with microbiome disruption, as assessed by low diversity or expansion of the pathobiont Enterococcus. We validated this observation experimentally, finding that sucrose exacerbated antibiotic-induced Enterococcus expansion in mice. Taken together, our results suggest that avoiding sugar-rich foods during antibiotic treatment may reduce microbiome injury. One Sentence SummaryAnalyses of hematopoietic cell transplant patients and of mice uncover links between foods and microbiome disruption.

microbiology↗

bioRxiv2024

Manipulation of the brown glume and internode 1 gene leads to alterations in lignified tissue coloration, lignification, and pathogen resistance in wheat

Lignin is a crucial component of the cell wall, providing mechanical support and protection against biotic and abiotic stresses. However, little is known about wheat lignin-related mutants and their roles in pathogen defense. In this study, we identified an ethyl methanesulfonate (EMS)-derived Aegilops tauschii mutant named brown glume and internode 1 (bgi1), which exhibits reddish-brown pigmentation in various tissues, including internodes, spikes, and glumes. Using map-based cloning and single nucleotide polymorphism (SNP) analysis, we identified AET6Gv20438400 (BGI1) as the leading candidate gene, encoding the TaCAD1 protein. The mutation occurred in the splice acceptor site of the first intron, resulting in a premature stop codon in BGI1. We validated the function of BGI1 using loss-of-function EMS and gene editing knockout mutants, both of which displayed reddish-brown pigmentation in lignified tissues. BGI1 knockout mutants exhibited reduced lignin content and shearing force relative to wild type, while BGI1 overexpression transgenic plants showed increased lignin content and enhanced disease resistance against common root rot and Fusarium crown rot. We confirmed that BGI1 exhibits CAD activity both in vitro and in vivo, playing an important role in lignin biosynthesis. BGI1 was highly expressed in the stem and spike and localized in the cytoplasm. Transcriptome analysis revealed the regulatory networks associated with BGI1. Finally, we demonstrated that BGI1 interacts with TaPYL-1D, potentially involved in the abscisic acid signaling pathway. The identification and functional characterization of BGI1 significantly advance our understanding of CAD proteins in lignin biosynthesis and plant defense against pathogen infection in wheat.

plant biology↗

bioRxiv2024

Protective effects of PDGF-AB/BB against cellular senescence in human intervertebral disc

Cellular senescence, characterized by a permanent state of cell cycle arrest and a secretory phenotype contributing to inflammation and tissue deterioration, has emerged as a target for age-related interventions. Accumulation of senescent cells is closely linked with intervertebral disc (IVD) degeneration, a prevalent age-dependent chronic disorder causing low back pain. Previous studies have highlighted that platelet-derived growth factor (PDGF) mitigated IVD degeneration through anti-apoptosis, anti-inflammation, and pro-anabolism. However, its impact on IVD cell senescence remains elusive. In this study, human NP and AF cells derived from aged, degenerated IVDs were treated with recombinant human (rh) PDGF-AB/BB for 5 days and changes of transcriptome profiling were examined through mRNA sequencing. NP and AF cells demonstrated similar but distinct responses to the treatment. However, the effects of PDGF-AB and BB on human IVD cells were comparable. Specifically, PDGF-AB/BB treatment resulted in downregulation of gene clusters related to neurogenesis and response to mechanical stimulus in AF cells while the downregulated genes in NP cells were mainly associated with metabolic pathways. In both NP and AF cells, PDGF-AB and BB treatment upregulated the expression of genes involved in cell cycle regulation, mesenchymal cell differentiation, and response to reduced oxygen levels, while downregulating the expression of genes related to senescence associated phenotype, including oxidative stress, reactive oxygen species (ROS), and mitochondria dysfunction. Network analysis revealed that PDGFRA and IL6 were the top hub genes in treated NP cells. Furthermore, in irradiation-induced senescent NP cells, PDGFRA gene expression was significantly reduced compared to non-irradiated cells. However, rhPDGF-AB/BB treatment increased PDGFRA expression and mitigated the senescence progression through increased cell population in the S phase, reduced SA-{beta}-Gal activity, and decreased expression of senescence related regulators including P21, P16, IL6, and NF-{kappa}B. Our findings reveal a novel anti-senescence role of PDGF in the IVD, making it a promising potential candidate to delay aging-induced IVD degeneration. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=102 SRC="FIGDIR/small/617862v2_ufig1.gif" ALT="Figure 1"> View larger version (26K): org.highwire.dtl.DTLVardef@1f151d0org.highwire.dtl.DTLVardef@324747org.highwire.dtl.DTLVardef@e58c92org.highwire.dtl.DTLVardef@6fe26c_HPS_FORMAT_FIGEXP M_FIG C_FIG

cell biology↗

bioRxiv2024

Arginine methylation coordinates with phosphorylation to regulate NADP+ synthesis

NADK is the sole cytosolic enzyme responsible for synthesizing NADP+ from NAD+ within cells. The homeostasis of NAD+/NADP+ is controlled by NADK, usually dysregulated in various cancers, yet the precise underlying regulatory mechanisms remain largely unknown. In this study, we discover that PRMT6 methylates NADK at R39, R41, and R45, resulting in the suppression of NADK kinase activity and NADP+ synthesis. Mutations of these sites promote cancer cell proliferation and tumor growth. PRMT6-mediated methylation of NADK coordinates with Akt-mediated phosphorylation to regulate NADK, which stimulates its activity to increase NADP+ production through relief of an autoinhibitory function inherent to its amino terminus. PRMT6 also inhibits NADK activity in a phosphorylation-independent manner. Furthermore, NADK methylation is upregulated by RB1/E2F pathway in high-fat diet mice. Downregulation of NADK methylation in HCC enhances NADP+ production to promote cancer development. Our findings illuminate the molecular regulatory mechanisms governing NAD+/NADP+ homeostasis, suggesting that the PRMT6-NADK axis emerges as a direct player in high energy state. Furthermore, our research suggests potential therapeutic targets through chemical and genetic interventions. SignificancePrevious studies revealed that phosphorylation of NADK activates its activity in response to nutrient or other signaling pathways. Here, we discovered that PRMT6 methylates NADK at residues R39, R41, and R45, leading to the suppression of NADK kinase activity and NADP+ synthesis. This PRMT6-mediated methylation works in conjunction with Akt-mediated phosphorylation to regulate NADK. Additionally, we found that NADK methylation is upregulated by the RB1/E2F pathway in mice on a high-fat diet. In hepatocellular carcinoma (HCC), the downregulation of NADK methylation enhances NADP+ production, thereby promoting cancer development. Our findings provide a significant breakthrough in understanding the regulation of NADK and its response to environmental factors.

cancer biology↗

bioRxiv2024

Latexin facilitates neointimal formation via promoting smooth muscle cell proliferation and macrophage migration

RationaleNeointimal formation is the major cause of cardiovascular diseases such as atherosclerosis and restenosis. Although restenosis rates are significantly reduced by the development of drug-eluting, the stent may not be implanted at all atherosclerotic sites, and long-term dual anti-platelet therapy is needed after stent implantation. Thus, it is essential to elucidate the detailed mechanisms underlying neointimal formation for developing novel therapies. Latexin (LXN), a previously identified pro-inflammatory protein, is highly expressed in vasculature and its expression is regulated by shear stress. Whether it plays a role in vascular remodeling, however, remains unknown. ObjectiveTo determine whether LXN is involved in neointimal formation, and if so, to define the molecular mechanisms involved. Methods and ResultsWe found that the expression of LXN was significantly increased in neointimal hyperplasia, as determined by western blot. Immunofluorescent staining indicated that increased LXN expression was predominantly localized in smooth muscle cells and macrophages. To determine the cell specific roles of LXN in neointimal formation after injury, we generated global, smooth muscle cell (SMC)-specific, endothelial specific-, and myeloid-specific LXN knockout (KO) mice. We found that global, SMC-, and myeloid-specific LXN deficiency markedly prevented neointimal hyperplasia in mice after carotid artery ligation, whereas LXN deficiency in endothelial cells had no effects. Mechanistically, we found that LXN deficiency in SMCs significantly attenuated SMC proliferation and migration, mainly through inhibiting the expression of platelet-derived growth factor (PDGF) receptors. Intriguely, LXN deficiency in macrophages inhibited monocyte chemoattractant protein-1 (MCP-1)-induced macrophage migration through inhibiting ERK phosphorylation. ConclusionsIn summary, we for the first time demonstrated that LXN is essentially involved in SMC proliferation and microphage migration. Specific inhibition of LXN signaling may provide a novel therapeutic strategy for the treatment of cardiovascular diseases, such as restenosis and atherosclerosis. Novelty and SignificanceO_ST_ABSWhat is known?C_ST_ABSO_LILatexin (LXN) is considered to be a novel pro-inflammatory protein and its expression is responsive to laminar shear stress. C_LIO_LIVascular inflammation, SMC proliferation, and macrophage migration are critical events in neointimal hyperplasia. C_LI What new information does this article contribute?O_LILXN is elevated in carotid artery ligation-induced neointimal hyperplasia in mice. C_LIO_LISMC-specific LXN deficiency prevents neointimal hyperplasia through inhibiting SMC proliferation migration via attenuating platelet-derived growth factor receptor expression. C_LIO_LIMyeloid-specific LXN deficiency prevents neointimal hyperplasia through inhibiting monocyte chemoattractant protein-1-induced macrophage migration and extracellular signal-regulated kinase phosphorylation. C_LI Neointimal formation is the major cause of cardiovascular disease such as atherosclerosis and restenosis after stenting or balloon angioplasty. Because of the development of drug-eluting stents, restenosis rates have been significantly reduced; however, it is still essential to explore the detailed mechanisms underlying neointimal hyperplasia. Latexin (LXN) is considered a novel pro-inflammatory protein that is ubiquitously expressed in vascular and immune cells. We found that LXN is elevated in neointimal hyperplasia, and its deficiency in SMCs and macrophages, but not in ECs, markedly prevents neointimal formation after carotid artery ligation in mice. Mechanistically, LXN deficiency in SMCs prevents SMC proliferation and migration via attenuation of platelet-derived growth factor receptor expression. Further, myeloid-specific LXN deficiency inhibits monocyte chemoattractant protein-1-induced macrophage migration via attenuation of extracellular signal-regulated kinase phosphorylation. For the first time, the present study demonstrated that LXN is a crucial mediator implicated in SMC biology and macrophage migration.

physiology↗

bioRxiv2024

Enhanced bacterial chemotaxis in confined microchannels: Optimal performance in lane widths matching circular swimming radius

Understanding bacterial behavior in confined environments is helpful for elucidating microbial ecology and developing strategies to manage bacterial infections. While extensive research has focused on bacterial motility on surfaces and in porous media, chemotaxis in confined spaces remains poorly understood. Here, we investigate the chemotaxis of Escherichia coli within microfluidic lanes under a linear concentration gradient of L-aspartate. We demonstrate that E. coli exhibits significantly enhanced chemotaxis in lanes with sidewalls compared to open surfaces. We attribute this phenomenon primarily to the intrinsic chiral clockwise circular motion of surface-swimming bacteria and the subsequent alignment effect upon collision with the sidewalls. By varying lane widths, we identify that an 8 m width--approximating the radius of bacterial circular swimming on surfaces--maximizes chemotactic drift velocity. These results are supported by both experimental observations and stochastic simulations, establishing a clear proportional relationship between optimal lane width and the radius of bacterial circular swimming. Further geometric analysis provides an intuitive understanding of this phenomenon. Our results may offer insights into bacterial navigation in complex biological environments such as host tissues and biofilms, providing a preliminary step toward exploring microbial ecology in confined habitats and potential strategies for controlling bacterial infections.

biophysics↗

bioRxiv2024

Lysophospholipid headgroup size, and acyl chain length and saturation differentially affect vacuole acidification, Ca2+ transport, and fusion

SNARE-mediated membrane fusion is regulated by the lipid composition of the engaged bilayers. Lipids impact fusion through direct protein-lipid interactions or through modulating the physical properties of membranes to affect protein function. Lysophospholipids (LPLs) can affect membrane curvature, fluidity and energy of deformation. Their effects are due to their head group, and the length and saturation of their single acyl chains. Here we examined how the properties of LPLs affect yeast vacuole fusion and ion transport. We found that lysophosphatidylcholine (LPC) with acyl chains containing 14-18 carbons inhibited fusion with IC50 values of {cong} 40-120 {micro}M. While acyl chain length moderately affected fusion, the head group played a major role. Unlike LPCs, Lysophosphatidic acid (LPA 18:1) failed to fully inhibit fusion, while lysophosphatidylethanolamine (LPE 18:1) had no effect. Separately we found that changes in acyl chain length and saturation differentially affected Ca2+ transport and vacuole acidification. Together these data show that the effects of LPLs on membrane fusion and ion transport were due to a combination of head group type and acyl chain length.

biochemistry↗

bioRxiv2024

Tumor-induced endothelial RhoA activation mediates tumor cell transendothelial migration and metastasis

Abstract/SummaryThe endothelial barrier plays an active role in transendothelial tumor cell migration during metastasis, however, the endothelial regulatory elements of this step remain obscure. Here we show that endothelial RhoA activation is a determining factor during this process. Breast tumor cell-induced endothelial RhoA activation is the combined outcome of paracrine IL-8-dependent and cell-to-cell contact {beta}1 integrin-mediated mechanisms, with elements of this pathway correlating with clinical data. Endothelial-specific RhoA blockade or in vivo deficiency inhibited the transendothelial migration and metastatic potential of human breast tumor and three murine syngeneic tumor cell lines, similar to the pharmacological blockade of the downstream RhoA pathway. These findings highlight endothelial RhoA as a potent, universal target in the tumor microenvironment for anti-metastatic treatment of solid tumors.

physiology↗

bioRxiv2024

Integrating various Experimental Information to Assist Protein Complex Structure Prediction by GRASP

Protein complex structures are essential for understanding of biological activities and drug development. Improving complex structure prediction accuracy of AI models for cases such as antigen-antibody complexes is expected to further enhance their applicability. Meanwhile, a large variety of experimental methods are used to provide structural insights for protein complexes, with only sparse or approximate knowledge obtained. A general tool is needed to integrate AI models with limited experimental information for high-throughput and accurate protein complex structure prediction. To efficiently and flexibly incorporate the different forms of experimental information, we introduce here GRASP. GRASP outperforms existing tools in handling both simulated and real-world experimental restraints including those obtained from XL, CL, CSP, and DMS. As an example, GRASP excels in predicting antigen-antibody complex structures, even surpassing AF3 when utilizing experimental DMS and CL restraints. In addition to accelerating the restrained modeling process, its ability to integrate multiple forms of restraints makes it capable of integrative modeling. We also showcase its potential in modeling protein structural interactome in the near-cellular condition based on large-scale in vivo XL data for mitchondria.

bioinformatics↗

bioRxiv2024

MdLRR-RLK1-MdATG3 module enhances the resistance of apples to abiotic stress via autophagy

LRR-RLKs play a key role in plant responses to stress, although their physiological functions under abiotic stress are not yet fully understood. MdLRR-RLK1 was found to regulate plant growth and development and to increase tolerance to salt and drought stress. MdLRR-RLK1 interacts with MdATG3, which ubiquitinates and degrades MdLRR-RLK1. MdATG3 enhances salt and drought tolerance through autophagy, interacting with MdATG8F/I-like in apple. These findings reveal the interaction between MdLRR-RLK1 and MdATG3, suggesting mechanisms that regulate apple growth and resistance to abiotic stress.

molecular biology↗

bioRxiv2024

Shade Inhibits Cambial Activity in Populus Stems by the SPL16/SPL23-Mediated Cytokinin Pathway

Trees in natural forests or plantations often encounter neighbor proximity signal that negatively impacts wood production. However, the molecular basis underlying shade-regulation of vascular cambial activity during stem radial growth remains unknown in woody species. Here, we revealed that high stand density and simulated shade (low R/FR ratio) suppress the division and differentiation of cambial cells in poplar stems. A genome-wide screen for Populus SQUAMOSA PROMOTER BINDING PROTEIN-LIKE (SPL) genes identified that SPL16 and SPL23 are preferentially expressed in the phloem and cambium, being downregulated by simulated shade. Knocking out SPL16/23 impaired cambial activity, whereas phloem-specific overexpression of SPL16 stimulated cambial proliferation and mitigated the shade-inhibition of cambial activity. Additionally, shade decreased bioactive cytokinin (CK) levels by suppressing the expression of CK biosynthesis genes IPT5a, IPT5b and LOG1b in poplar stems. Molecular and genetic studies reveled that SPL16/23 directly activate IPT5s/LOG1b expression to promote CK biosynthesis and cambial activity. Moreover, elevated miR156 expression in shade-treated stems regulated SPL16/23 at the post-transcriptional level, mediating shades effects on cambial activity. Collectively, our findings unravel that the miR156-SPL16/23-IPT5/LOG1-cytokinin pathway operates in the shade-mediated inhibition of cambial activity, providing potential targets for the genetic improvement of shade-tolerant trees.

plant biology↗