Biology subjects

Wu, Y.

Publications and source records attributed to Wu, Y..

At least 595 records · Page 33Linked to original sources

bioRxiv2023

Disrupted excitation-inhibition balance in cognitively normal individuals at risk of Alzheimers disease

BackgroundSex differences impact Alzheimers disease (AD) neuropathology, but cell-to-network level dysfunctions in the prodromal phase are unclear. Alterations in hippocampal excitation-inhibition balance (EIB) have recently been linked to early AD pathology. ObjectiveExamine how AD risk factors (age, APOE-{varepsilon}4, amyloid-{beta}) relate to hippocampal EIB in cognitively normal males and females using connectome-level measures. MethodsIndividuals from the OASIS-3 cohort (age 42-95) were studied (N = 437), with a subset aged 65+ undergoing neuropsychological testing (N = 231). ResultsIn absence of AD risk factors (APOE-{varepsilon}4/A{beta}+), whole-brain EIB decreases with age more significantly in males than females (p = 0.021, {beta} = -0.007). Regression modeling including APOE-{varepsilon}4 allele carriers (A{beta}-) yielded a significant positive AGE-by-APOE interaction in the right hippocampus for females only (p = 0.013, {beta} = 0.014), persisting with inclusion of A{beta}+ individuals (p = 0.012, {beta} = 0.014). Partial correlation analyses of neuropsychological testing showed significant associations with EIB in females: positive correlations between right hippocampal EIB with categorical fluency and whole-brain EIB with the trail-making test (p < 0.05). ConclusionSex differences in EIB emerge during normal aging and progresses differently with AD risk. Results suggest APOE-{varepsilon}4 disrupts hippocampal balance more than amyloid in females. Increased excitation correlates positively with neuropsychological performance in the female group, suggesting a duality in terms of potential beneficial effects prior to cognitive impairment. This underscores the translational relevance of APOE-{varepsilon}4 related hyperexcitation in females, potentially informing therapeutic targets or early interventions to mitigate AD progression in this vulnerable population.

neuroscience↗

bioRxiv2023

Exploiting Substrate Specificities of 6-O-Sulfotransferases to Enzymatically Synthesize Keratan Sulfate Oligosaccharides

Keratan sulfate (KS) is a glycosaminoglycan that is widely expressed in the extracellular matrix of various tissue types where it is involved in many biological processes. Herein, we describe a chemo-enzymatic approach to prepare well-defined KS oligosaccharides by exploiting known and newly discovered substrate specificities of relevant sulfotransferases. The premise of the approach is that recombinant GlcNAc-6-O-sulfotransferases (CHST2) only sulfates terminal GlcNAc moieties to give GlcNAc6S that can be galactosylated by B4GalT4. Furthermore, CHST1 can modify internal galactosides of a poly-LacNAc chain, however, it was found that a GlcNAc6S residue greatly increases the reactivity of CHST1 of a neighboring and internal galactoside. The presence of a 2,3-linked sialoside further modulates the site of modification by CHST1, and a galactoside flanked by 2,3-Neu5Ac and GlcNAc6S is preferentially sulfated over other Gal residues. The substrate specificities of CHST1 and 2 were exploited to prepare a panel of KS oligosaccharides including selectively sulfated N-glycans. The compounds and several other reference derivatives were used to construct a microarray that was probed for binding by several plant lectins, Siglec proteins and hemagglutinins of influenza viruses. It was found that not only the sulfation pattern but also presentation of epitopes as part of an O- or N-glycan determines binding properties.

biochemistry↗

bioRxiv2023

Pretrainable Geometric Graph Neural Network for Antibody Affinity Maturation

Increasing the binding affinity of an antibody to its target antigen is a crucial task in antibody therapeutics development. This paper presents a pretrainable geometric graph neural network, GearBind, and explores its potential in in silico affinity maturation. Leveraging multi-relational graph construction, multi-level geometric message passing and contrastive pretraining on mass-scale, unlabeled protein structural data, GearBind outperforms previous state-of-the-art approaches on SKEMPI and an independent test set. A powerful ensemble model based on GearBind is then derived and used to successfully enhance the binding of two antibodies with distinct formats and target antigens. ELISA EC50 values of the designed antibody mutants are decreased by up to 17 fold, and KD values by up to 6.1 fold. These promising results underscore the utility of geometric deep learning and effective pretraining in macromolecule interaction modeling tasks.

bioinformatics↗

bioRxiv2023

A dynamic model of neurovascular coupling network accounting for capillary K+-sensing vasomotion

Neurovascular coupling (NVC) is a fundamental unit that elucidates the regulation of vascular activity by neuronal electrical activity, ensuring adequate blood flow to the brains active regions and optimizing neural function. In this article, we propose a comprehensive dynamic model of a neural vascular coupling network that integrates the capillary K+ sensing mechanism and its impact on vascular motion. Our computational framework incorporates the dynamics of neurons, astrocytes, and smooth muscle cells at the cellular level. By integrating recent experimental findings, we have successfully demonstrated the ability of capillary endothelial cells to detect localized fluctuations in extracellular potassium (K+) concentration via the Kir2.1 channel situated on their membranes. Subsequently, these cells transmit this signal to smooth muscle cells, initiating the release of vasoactive substances and thereby facilitating vascular movement. This sequence of events serves as the fundamental basis of our model. Furthermore, the simulation we provide supports the inclusion of a temperature term in our model, enabling accurate replication of experimental observations: variations in neuronal electrical activity resulting from an increase in temperature and subsequent vasoconstriction. In conclusion, our dynamic model presents a valuable tool for investigating the mechanisms underlying neurovascular coupling and the role of capillary K+ sensing in regulating vascular activity. It enhances our understanding of brain function and offers insights for developing therapeutic interventions for neurovascular diseases. Author summaryIt is widely accepted that neuronal activity induces vasodilation, resulting in increased blood flow, while vascular activity provides energy supply to the nervous system. The role of astrocytes in these processes has been extensively studied, revealing their dual involvement in neuronal firing and facilitation of energy delivery to the nervous system through blood vessels. As cellular mediators of bidirectional processes, astrocytes play a crucial role in promoting neurovascular coupling, leading to the formation of neurovascular coupling units. Building upon existing experimental observations and previous theoretical reports, the present study successfully replicates the phenomenon of vasodilation caused by an increase in potassium ion concentration in the perivascular space, as well as vasoconstriction resulting from elevated potassium ion concentration. A new neuron-astrocyte-endothelial-smooth muscle cell coupling network model, incorporating temperature considerations, was constructed to achieve these outcomes. Additionally, by manipulating temperature, the experimental observation of neuronal vasoconstriction during febrile seizures was successfully reproduced. These results highlight the significance of the neurovascular coupling unit as the fundamental entity for investigating the functions and mechanisms of the nervous system and brain.

neuroscience↗

bioRxiv2023

Large-scale population genomics of Malayan pangolins reveals deep diversification and a new species

BackgroundArchipelagos and oceanic islands often present high percentage of endemism due to rapid speciation. The Malayan pangolin is a species distributing at both mainland (southern Yunnan, China) and oceanic islands via Malayan peninsula, which may result in deep differentiation among populations. In-depth investigation of population structure and genetic consequences for such species is of vital importance for their protection and conservation, practically for the critically endangered Malayan pangolin that is suffering from poaching, illegal trade, and habitat loss. ResultsHere we carried out a large-scale population genomic analysis for Malayan pangolins, and revealed three highly distinct genetic populations in this species, two of which are now being reported for the first time. Based on multiple lines of genomic and morphological evidence, we postulate the existence of a new pangolin species (Manis_1). Genetic diversity and recent inbreeding were both at a moderate level for both Malayan pangolins and Manis_1, but mainland Malayan pangolins presented relatively lower genetic diversity, higher inbreeding and fitness cost than island populations. ConclusionsWe found extremely deep and graded differentiation in Malayan pangolins, with two newly discovered genetic populations and a new pangolin species that is closely related to the Philippine pangolin than the typical Malayan pangolin, but a distant relative of the Indian pangolin. Anthropogenic factors did not significantly weaken the basis of genetic sustainability for Malayan pangolins, but mainland Malayan pangolins should be paid more attention for conservation due to higher genetic risks than island populations.

genomics↗

bioRxiv2023

Purifying selection and adaptive evolution proximate to the zoonosis of SARS-CoV-1 and SARS-CoV-2

Over the past two decades the pace of spillovers from animal viruses to humans has accelerated, with COVID-19 becoming the most deadly zoonotic disease in living memory. Prior to zoonosis, it is conceivable that the virus might largely be subjected to purifying selection, requiring no additional selective changes for successful zoonotic transmission. Alternatively, selective changes occurring in the reservoir species may coincidentally preadapt the virus for human-to-human transmission, facilitating spread upon cross-species exposure. Here we quantify changes in the genomes of SARS-CoV-2 and SARS-CoV-1 proximate to zoonosis to evaluate the selection pressures acting on the viruses. Application of molecular-evolutionary and population-genetic approaches to quantify site-specific selection within both SARS-CoV genomes revealed strong purifying selection across many genes at the time of zoonosis. Even in the viral surface-protein Spike that has been fast-evolving in humans, there is little evidence of positive selection proximate to zoonosis. Nevertheless, in SARS-CoV-2, NSP12, a core protein for viral replication, exhibited a region under adaptive selection proximate to zoonosis. Furthermore, in both SARS-CoV-1 and SARS-CoV-2, regions of adaptive selection proximate to zoonosis were found in ORF7a, a putative Major Histocompatibility Complex modulatory gene. These findings suggest that these replication and immunomodulatory proteins have played a previously underappreciated role in the adaptation of SARS coronaviruses to human hosts.

evolutionary biology↗

bioRxiv2023

OsNAC2 maintains the homeostasis of immune responses to bacterial blight through the OsEREBP1 in rice

Rice bacterial blight, caused by Xanthomonas oryzae pv. Oryzae (Xoo), threatens plant growth and yield. However, the molecular mechanisms underlying rice immunity against Xoo remain elusive. Here, we demonstrated down-regulation of a NAC (NAM-ATAF-CUC) transcription factor OsNAC2 enhanced resistance to bacterial blight disease in rice. Consistently, salicylic acid (SA) biosynthesis was greatly attenuated when OsNAC2 overexpressed. Furthermore, study demonstrated that OsNAC2 can down-regulated the expression of SA synthesis genes, thus mediating SA signal transmission. Simultaneously, OsNAC2 interacted with OsEREBP1 (AP2/ERF family) in the nucleus, may be bloking the inhibition of OsNAC2 to OsICS1, OsPAL3 and so on. Furthermore, OsEREBP1 interacted with OsXb22a in the cytoplasm to exert its positive regulatory effects to bacterial blight. However, OsNAC2-overexpression kept OsEREBP1 in the nucleus and be rapidly degraded in pathogen infection, which adversely affects the interaction of OsEREBP1-OsXb22a. Our results determined that OsNAC2 inhibits the SA signaling and stably interacts with OsEREBP1 to maintain disease resistance. This OsNAC2-OsEREBP1-based homeostatic mechanism provides new insights into rice disease resistance, and it may be useful for improving the disease resistance of important crops through breeding.

molecular biology↗

bioRxiv2023

BrrRCO, encoding a homeobox protein, is involved in leaf lobe development in Brassica rapa

Leaf shape is a vital economic and developmental trait in leafy vegetable Chinese cabbage (Brassica rapa L. subsp. pekinensis), which varies from smooth to deeply lobed, whereas the molecular basis remains unclear. Here, we detected an incompletely dominant major quantitative trait locus (QTL) qBrrLLA10 for the lobed-leaf trait in B. rapa, and identified BrrRCO, encoding a HD-Zip transcription factor, as the casual gene underlying lobed leaf formation in B. rapa. Genotyping analysis showed that abundant variations in promoter of BrrRCO is responsible for leaf lobe variation, and the expression levels and promoter activity were significantly affected by the promoter variations between two parents. BrrRCO was a nucleus-specific protein and possess highest expression level at the bases of each lobe. Ectopic overexpression of BrrRCO in Arabidopsis led to deeply lobed leaves have never been seen in wild type, and leaf lobe development was blocked when BrrRCO expression was down-regulated through virus-induced gene silencing assays. Taken together, our findings revealed that BrrRCO positively regulate leaf lobe formation in Chinese cabbage, and the cis-regulatory element modifications result in functional variation of BrrRCO, providing a novel insight into the leaf shape improvement in Chinese cabbage and other Brassica species. HighlightBrrRCO is essential for leaf lobe formation by repressing local growth of leaf margin cells in B. rapa, and cis-regulatory modifications cause the different allele effects.

plant biology↗

bioRxiv2023

Mechano-induced homotypic patterned domain formation by monocytes

Matrix stiffness and corresponding mechano-signaling play indispensable roles in cellular phenotypes and functions. How tissue stiffness influences the behavior of monocytes, a major circulating leukocyte of the innate system, and how it may promote the emergence of collective cell behavior is less understood. Here, using tunable collagen-coated hydrogels of physiological stiffness, we show that human primary monocytes undergo a dynamic local phase separation to form highly patterned multicellular multi-layered domains on soft matrix. Local activation of the {beta}2 integrin initiates inter-cellular adhesion, while global soluble inhibitory factors maintain the steady-state domain pattern over days. Patterned domain formation generated by monocytes is unique among other key immune cells, including macrophages, B cells, T cells, and NK cells. While inhibiting their phagocytic capability, domain formation promotes monocytes survival. We develop a computational model based on the Cahn-Hilliard equation, which includes combined local activation and global inhibition mechanisms of intercellular adhesion suggested by our experiments, and provides experimentally validated predictions of the role of seeding density and both chemotactic and random cell migration on pattern formation.

biophysics↗

bioRxiv2023

Competitive fitness and homologous recombination of SARS-CoV-2 variants of concern

SARS-CoV-2 variants continue to emerge and cocirculate in humans and wild animals. The factors driving the emergence and replacement of novel variants and recombinants remain incompletely understood. Herein, we comprehensively characterized the competitive fitness of SARS-CoV-2 wild type (WT) and three variants of concern (VOCs), Alpha, Beta and Delta, by coinfection and serial passaging assays in different susceptible cells. Deep sequencing analyses revealed cell-specific competitive fitness: the Beta variant showed enhanced replication fitness during serial passage in Caco-2 cells, whereas the WT and Alpha variant showed elevated fitness in Vero E6 cells. Interestingly, a high level of neutralizing antibody sped up competition and completely reshaped the fitness advantages of different variants. More importantly, single clone purification identified a significant proportion of homologous recombinants that emerged during the passage history, and immune pressure reduced the frequency of recombination. Interestingly, a recombination hot region located between nucleotide sites 22995 and 28866 of the viral genomes could be identified in most of the detected recombinants. Our study not only profiled the variable competitive fitness of SARS-CoV-2 under different conditions, but also provided direct experimental evidence of homologous recombination between SARS-CoV-2 viruses, as well as a model for investigating SARS-CoV-2 recombination. ImportanceSARS-CoV-2 variants or subvariants keep emerging and the epidemic strains keeps changing in humans and animals. The continued replacement of the epidemic strains was attributed to higher competitive fitness evolved by the newly appeared ones than the older ones, but which factors affect the final outcomes are still not entirely clear. In this study, we performed in vitro coinfection and serial passage with three VOCs and WT under different conditions. Our results showed that the competition outcomes of these viral strains varied in different cell lines or under different immune pressure, confirming the probable effects of these two factors for the competitive fitness of different SARS-CoV-2 viral strains. Meanwhile, strikingly, we found that coinfection and serial passage with different SARS-CoV-2 viral strains can mimic the recombination process of SARS-CoV-2 occurred in coinfection individual, indicating it is a novel model to investigate the SARS-CoV-2 recombination mechanism.

microbiology↗

bioRxiv2023

Sorcin-STAT3-Serpin E1/CCL5 axis can be the trigger of pancreatic cancer-associated new-onset diabetes

A rise in blood glucose is the early warning signs of underlying pancreatic cancer (PC), which could be the externalization of genetic events in PC progression. But there is still a vacancy in the field of mechanism research on pancreatic cancer-associated new-onset diabetes (PCAND). Using siRNA-mediated gene knockdown in vitro, we made MIN6 cells incubated with conditioned media from transfected PC cells, and detected its response. Immunological techniques were used to explore the interaction between sorcin and STAT3. Human cytokine array was performed to explore the inflammatory cytokines downstream of sorcin. In the present study, we have identified a PCAND driver gene SRI. In PC cells, sorcin and STAT3 form a positive feedback loop to enhance the transcription of serpin E1 and CCL5, which can impair nearby islet {beta}-cells, likely by activating the p38 pathway. In 88 biopsies, expression of sorcin was elevated in PC tissues, especially so in PCAND patient samples. Furthermore, clinical-SRI gene combination model can better distinguish PCAND from T2DM, and serpin E1 level is higher in the peripheral blood samples from PCAND than T2DM. Thus, Sorcin could be the key driver in PCAND, and figuring out sorcin-STAT3-serpin E1/CCL5 signaling axis can help us better understand the pathogenesis of PCAND and identify potential biomarkers. Statement of significanceThis study mapped out a novel sorcin-STAT3-Serpin E1/CCL5 signaling axis in pancreatic cancer cells, which explains how early pre-symptomatic pancreatic cancer may coincide with new-onset diabetes in some patients.

cancer biology↗

bioRxiv2023

Design of SARS-CoV-2 protease inhibitors with improved affinity and reduced sensitivity to mutations

Inhibitors of the SARS-CoV-2 main protease (Mpro) such as nirmatrelvir (NTV) and ensitrelvir (ETV) have proven effective in reducing the severity of COVID-19, but the presence of resistance-conferring mutations in sequenced viral genomes raises concerns about future drug resistance. Second-generation oral drugs that retain function on these mutants are thus urgently needed. We hypothesized that the covalent HCV protease inhibitor boceprevir (BPV) could serve as the basis for orally bioavailable drugs that inhibit SARS-CoV-2 Mpro more tightly than existing drugs. Performing structure-guided modifications of BPV, we developed a picomolar-affinity inhibitor, ML2006a4, with antiviral activity, oral pharmacokinetics, and therapeutic efficacy similar or superior to NTV. A crucial feature of ML2006a4 is a novel derivatization of the ketoamide reactive group that improves cell permeability and oral bioavailability. Finally, ML2006a4 is less sensitive to several mutations that cause resistance to NTV or ETV and occur in the natural SARS-CoV-2 population. Thus, anticipatory drug design can preemptively address potential resistance mechanisms.

microbiology↗

bioRxiv2023

AMPK targets PDZD8 to trigger carbon source shift to glutamine

The shift of carbon utilisation from glucose to other nutrients is a fundamental metabolic adaptation to cope with the decreased glucose oxidation during fasting or starvation1. AMP-activated protein kinase (AMPK) plays crucial roles in manifesting physiological benefits accompanying glucose starvation or calorie restriction2. However, the underlying mechanisms are unclear. Here, we show that low glucose-induced activation of AMPK plays a decisive role in the shift of carbon utilisation from glucose to glutamine. We demonstrate that endoplasmic reticulum (ER)-localised PDZD8, which we identify to be a new substrate of AMPK, is required for the glucose starvation-promoted glutaminolysis. AMPK phosphorylates PDZD8 at threonine 527 (T527), and promotes it to interact with and activate the mitochondrial glutaminase 1 (GLS1), a rate-limiting enzyme of glutaminolysis3-5, and as a result the ER-mitochondria contact is strengthened. In vivo, PDZD8 enhances glutaminolysis, and triggers mitohormesis that is required for extension of lifespan and healthspan in Caenorhabditis elegans subjected to glucose starvation or caloric restriction. Muscle-specific re-introduction of wildtype PDZD8, but not the AMPK-unphosphorylable PDZD8-T527A mutant, to PDZD8-/- mice is able to rescue the increase of glutaminolysis, and the rejuvenating effects of caloric restriction in aged mice, including grip strength and running capacity. Together, these findings reveal an AMPK-PDZD8-GLS1 axis that promotes glutaminolysis and executes the anti-ageing effects of calorie restriction by promoting inter-organelle crosstalk between ER and mitochondria.

cell biology↗

bioRxiv2023

CircRNAs and their regulatory networks associated with the antioxidant enzymes and immune responses of Asian honey bee larvae to fungal infection

Non-coding RNA (ncRNA) plays an important role in the regulation of immune responses, growth, and development in plants and animals. Here, the identification, characteristic investigation, and molecular verification of circRNAs in Apis cerana cerana larval guts were conducted, and the expression pattern of larval circRNAs during Ascosphaera apis infection was analyzed. This was followed by exploration of the potential regulatory part of differentially expressed circRNAs (DEcircRNAs) in host immune responses. A total of 3178 circRNAs in the larval guts of A. c. cerana were identified, with a length distribution ranging from 15 nt to 96007 nt. Additionally, 45, 33, and 48 up-regulated circRNAs, as well as 110, 62, and 38 down-regulated circRNAs were identified in the A.-apis-inoculated 4-, 5-, and 6-day-old larval guts in comparison with the corresponding uninoculated larval guts. These DEcircRNAs were predicted to target 29, 25, and 18 parental genes, which were relative to 12, 20, and 17 GO terms as well as 144, 114, and 61 KEGG pathways, including five cellular and four humoral immune pathways containing melanization, phagosomes, lysosomes, endocytosis, apoptosis, MAPK, Ras, and Jak-STAT signaling pathways. Furthermore, complex competing endogenous RNA (ceRNA) regulatory networks were detected as being formed among DEcircRNAs, DEmiRNAs, and DEmRNAs. The target DEmRNAs were engaged in 36, 47, and 47 GO terms as well as 331, 332, and 331 pathways, including six cellular and six humoral immune-related pathways. In total, nineteen DEcircRNAs, five DEmiRNAs, and three mRNAs were included in the sub-networks relative to three antioxidant enzymes, including superoxide dismutase (SOD), catalase (CAT), and glutathione S-transferase (GST). Finally, back-splicing sites within 15 circRNAs and the difference in the 15 DEcircRNAs expression between uninoculated and A.-apis-inoculated larval guts were confirmed utilizing molecular methods. These findings not only enrich our understanding of bee host-fungal pathogen interactions, but also lay a foundation for illuminating the mechanism underlying the DEcircRNA-mediated immune defense of A. c. cerana larvae against A. apis invasion.

molecular biology↗

bioRxiv2023

Neural stimulation hardware for the selective intrafascicular modulation of the vagus nerve

The neural stimulation of the vagus nerve is able to modulate various functions of the parasympathetic response in different organs. The stimulation of the vagus nerve is a promising approach to treating inflammatory diseases, obesity, diabetes, heart failure, and hypertension. The complexity of the vagus nerve requires highly selective stimulation, allowing the modulation of target-specific organs without side effects. Here, we address this issue by adapting a neural stimulator and developing an intraneural electrode for the particular modulation of the vagus nerve. The neurostimulator parameters such as amplitude, pulse width, and pulse shape were modulated. Single-, and multi-channel stimulation was performed at different amplitudes. For the first time, I polyimide thin-film neural electrode was designed for the specific stimulation of the vagus nerve. In vivo experiments were performed in the adult minipig to validate to elicit electrically evoked action potentials and to modulate physiological functions selectively, validating the selectivity of intraneural stimulation. Electrochemical tests of the electrode and the neurostimulator showed that the stimulation hardware was working correctly. Stimulating the porcine vagus nerve resulted in selective modulation of the vagus nerve. Alpha, beta, and theta waves could be distinguished during single- and multi-channel stimulation. We have shown that the here presented system is able to activate the vagus nerve selectively and can therefore modulate the heart rate, diastolic pressure, and systolic pressure. The here presented system may be used to restore the cardiac loop after denervation by implementing biomimetic stimulation patterns. Presented methods may be used to develop intraneural electrodes adapted for various applications.

bioengineering↗

bioRxiv2023

A Recurrent Neural Circuit Mechanism of Temporal-scaling Equivariant Representation

Time perception is fundamental in our daily life. An important feature of time perception is temporal scaling (TS): the ability to generate temporal sequences (e.g., movements) with different speeds. However, it is largely unknown about the mathematical principle underlying TS in the brain. The present theoretical study investigates temporal scaling from the Lie group point of view. We propose a canonical nonlinear recurrent circuit dynamics, modeled as a continuous attractor network, whose neuronal population responses embed a temporal sequence that is TS equivariant. We find the TS group operators can be explicitly represented by a time-invariant control input to the network, whereby the input gain determines the TS factor (group parameter), and the spatial offset between the control input and the network state on the continuous attractor manifold gives rise to the generator of the Lie group. The recurrent circuits neuronal responses are consistent with experimental data. The recurrent circuit can drive a feedforward circuit to generate complex sequences with different temporal scales, even in the case of negative temporal scaling ("time reversal"). Our work for the first time analytically links the abstract temporal scaling group and concrete neural circuit dynamics.

neuroscience↗

bioRxiv2023

Polarized localization of kinesin-1 and RIC-7 drives axonal mitochondria anterograde transport

Mitochondria transport is crucial for mitochondria distribution in axons and is mediated by kinesin-1-based anterograde and dynein-based retrograde motor complexes. While Miro and Milton/TRAK were identified as key adaptors between mitochondria and kinesin-1, recent studies suggest the presence of additional mechanisms. In C. elegans, ric-7 is the only single gene described so far, other than kinesin-1, that is absolutely required for axonal mitochondria localization. Using CRISPR engineering in C. elegans, we find that Miro is important but is not essential for anterograde traffic, whereas it is required for retrograde traffic. Both the endogenous RIC-7 and kinesin-1 act at the leading end to transport mitochondria anterogradely. RIC-7 recruitment to mitochondria requires its N-terminal domain and partially relies on MIRO-1, whereas RIC-7 accumulation at the leading end depends on its disordered region, kinesin-1 and metaxin2. We conclude that polarized transport complexes containing kinesin-1 and RIC-7 form at the leading edge of mitochondria, and that these complexes are required for anterograde axonal transport. Summary statementAnterograde transport of axonal mitochondria is critical for maintenance of the mitochondria pool and neuronal health. Wu et al. show that the endogenous kinesin-1 and RIC-7 localize at the leading end of mitochondria to drive axonal anterograde transport in vivo.

cell biology↗

bioRxiv2023

A framework for Frizzled-G protein coupling and implications to the Wnt-PCP signaling pathways

The ten Frizzled receptors (FZDs) are essential in Wnt signaling and play important roles in embryonic development and tumorigenesis. Among these, FZD6 is closely associated with lens development. Understanding FZD activation mechanism is key to unlock these emerging targets. Here we present the cryo-EM structures of FZD6 and FZD3 which are known to relay non-canonical Wnt-PCP (planar cell polarity) signaling pathways as well as FZD1 in their G protein-coupled (active) and G protein-free (inactive) states, respectively. Comparison of the three inactive/active pairs unveiled a shared activation framework among all ten FZDs. Mutagenesis along with imaging and functional analysis on the human lens epithelial tissues suggested potential crosstalk between G-protein binding and Wnt-PCP signaling pathways. Together, this study provides an integrated understanding of FZD structure and function, and lays the foundation for developing therapeutic modulators to activate or inhibit FZD signaling for a range of disorders including cancers and cataracts.

biochemistry↗