Biology subjects

Lai, G.

Publications and source records attributed to Lai, G..

10 recordsLinked to original sources

bioRxiv2026

APP functions at the endomembrane system

INTRODUCTION: APP is a type I transmembrane protein, and its intracellular domain (AICD) interacts with FE65, X11, and mDAB1, et al., through the YENPTY motif. Accordingly, it has been proposed that the functions of APP are similar to Notch, which regulates gene expression through releasing NICD after combining with its ligands. However, the detailed underlying mechanisms of how FE65 is regulated by APP, as well as their target genes, remain unknown. METHODS: We overexpressed APP695 in N2a cells, and deleted/mutated APP in H4 cells by CRISPR-Cas9, respectively. The impacts of APP overexpression and ablation were detected by proteome comparison and immunoblotting. Thereafter, the subcellular localizations of APP and its binding protein FE65 were examined by immunofluorescence. RESULTS: APP overexpression not only resulted in its retention in Golgi apparatus (GA) and Endoplasmic reticulum (ER), but also induced FE65 clustering. In addition, it significantly reduced the protein level of ATF4 in N2a cells. On the contrary, knockdown of FE65 restored the protein level of ATF4. More importantly, APP overexpression also impaired autophagy. In contrast, knockout of APP rescued LC3 conversion. Of note, the APP Swedish mutant did not impact ER stress or the autophagic flux. Nevertheless, it facilitated the cleavage of APP-CTFs by gamma-secretase. DISCUSSION: The evidence presented in the current study demonstrates that APP is involved in stabilizing the endomembrane system and the subcellular transport of FE65. More importantly, the role of APP in regulating autophagy indicated that full-length APP could be considered a therapeutic target for preventing the development of AD.

neuroscience↗

bioRxiv2026

Genetic background diversifies mutational paths but converges on membrane depolarization for bleomycin resistance in yeast

Drug resistance evolution is shaped by both selective agent and genetic background in which resistant mutations arise, but most experimental evolution studies rely on a single genetic background. Here we performed parallel experimental evolution across six genetically diverged Saccharomyces cerevisiae strains, propagating 48 replicate populations for [~]225 generations under the selection of DNA-damaging chemotherapeutic bleomycin. Over 70% of the evolved populations acquired resistance with the magnitude and repeatability of adaptation varying markedly across genetic backgrounds. Whole-genome sequencing showed that bleomycin elevated single-nucleotide and insertion-deletion mutation rates, and induced background-specific aneuploidies and structural variants, including Ty-element-mediated translocations and tandem duplications. Notably, mutation rates varied up to 10-fold among backgrounds, with the most commonly-used lab strain exhibiting the highest mutagenic susceptibility, underscoring that evolutionary insights derived from single-background models may not universally generalize across a species. Despite this background-dependent genomic heterogeneity, we identified recurrent loss-of-function mutations in PMA1 and PTK2 that arose independently across nearly all genetic backgrounds and conferred strong resistance. Functional and biophysical assays revealed that these mutations impair Pma1p H+-ATPase activity and depolarize the plasma membrane, thereby limiting the cellular uptake of the positively charged drug. Our findings demonstrate that while the mutational routes to drug resistance are heavily shaped by genetic background, a convergent, background-independent mechanism centered on membrane potential regulation can dominate phenotypic adaptation. This work underscores the necessity of integrating genetic diversity into experimental evolution paradigm and nominates plasma membrane potential as an important lever for modulating chemotherapeutic efficacy.

genetics↗

bioRxiv2026

Intramembrane protease SPPL2b deficiency linked to synaptic proteostasis remodeling with brain aging

Signal peptide peptidase-like 2b (SPPL2b) is a brain-enriched intramembrane protease implicated in synaptic function, immune signaling, and neuronal development, but its physiological role in brain and neuronal homeostasis remains poorly understood. We investigated the impact of constitutive Sppl2b deletion on the brain proteome and neuronal function using quantitative shotgun proteomics in cortex and hippocampus from wild-type and SPPL2b-deficient mice at 3 and 12 months, combined with western blot, immunofluorescence, dendritic spine analysis, and behavioral testing. SPPL2b deficiency was associated with alterations in biological processes linked to axonal transport and synaptic vesicle trafficking, including consistent upregulation of the kinesin motor protein KIF1A and vesicle-associated membrane protein 2 (VAMP2). SPPL2b deletion also attenuated age-associated proteomic changes in synaptic pathways and was accompanied by increased dendritic spine density, morphological remodeling of pyramidal neurons, increased locomotor activity, and reduced anxiety-like behavior. These findings reveal a previously unrecognized association between SPPL2b and synaptic proteome remodeling during aging and nominate SPPL2b-dependent pathways as candidates for further mechanistic and functional investigation in neurodegenerative disease.

neuroscience↗

bioRxiv2025

Multimodal brain cell atlas across the adult macaque lifespan

High-throughput single-cell omics of non-human primate tissues present a remarkable opportunity to study primate brain aging. Here, we introduce a transcriptomic and chromatin accessibility landscape of 1,985,317 cells from eight brain regions of 13 cynomolgus female monkeys spanning adult lifespan including exceptionally old individuals up to 29-years old. This dataset uncovers dynamic molecular changes in critical brain functions such as synaptic communication and axon myelination, exhibiting a high degree of cell type and brain region specificity. We identify the multicellular networks of the pons and medulla as a previously unrecognized hotspot for aging. Furthermore, comparative analyses with human neurodegeneration datasets highlight both shared and distinct mechanisms contributing to aging and disease. In addition, we uncover transcription factors implicated in monkey brain aging and pinpoint aging-regulated loci linked to longevity and neurodegeneration. This spatiotemporal atlas will advance our understanding of primate brain aging and its broader implications for health and disease.

neuroscience↗

bioRxiv2024

Human tau promotes Warburg effect-like glycolytic metabolism under acute hyperglycemia conditions through modulating the homeostasis of protein-membrane association

The neurofilaments formed by hyperphosphorylated tau is a hallmark of tau-related neurodegenerative disease, including Alzheimers disease, tau related FTDP-17, Picks disease, et al. However, the biological functions of tau and the physiological significance of its phosphorylation are still not fully understood. By using human tau (441 a.a.) transgenic (hTau) mice in which murine tau has been deleted simultaneously, murine tau knockout (Tau KO) mice and C57BL/6J (C57) mice, unexpectedly, we found that under acute hyperglycemia conditions, JNK but not previously reported GSK-3{beta} mediated tau phosphorylation. Moreover, Akt, the upstream GSK-3{beta} inhibitory kinase, was activated in a tau dependent manner. By comparing the membrane-associated proteome, we found that human tau influenced the homeostasis of protein-membrane association under acute hyperglycemia conditions. Of note, with respect to WT and Tau KO mice, the membrane-association of Krts, TFAM, TRAP1, mTOR et al, were strengthened by human tau. Whereas, the membrane-association of ribosomal proteins Rpls, proteasome proteins Psmds, and mitochondrial proteins, such as COXs, Ndufa1, Mtnt4, et al, were impeded by human tau. In vitro study showed that aerobic glycolysis was promoted in the presence of human tau, which maintained NAD+/NADH ratio. On the other hand, it restricted oxidative phosphorylation level, modulated the activity of SDH, and reduced ROS production upon challenging by high glucose. Furthermore, under acute high glucose conditions, the presence of human tau significantly augmented Akt activation, but inhibited 4EBP phosphorylation simultaneously, indicating that human tau is also involved in regulating the alternative activation of mTORC1/2. In summary, the current study revealed that human tau played an important role in regulating glycolytic metabolism under acute high hyperglycemia conditions, which is similar with the Warburg-effect, through influencing the homeostasis of protein-membrane association.

molecular biology↗

bioRxiv2024

Cardiac Cycle Modulates Alpha and Beta Suppression during Motor Imagery.

IntroductionThe baroreceptor hypothesis posits that baroreceptors, located on the cardiac walls, are most active during systole, translating cardiac contraction information to the brain. Studies within this context have suggested that the systolic phase, characterised by increased noise, may compromise the processing of sensory stimuli. Although the effect of systolic and diastolic cardiac cycle phases on cognition, perception, and action has been widely documented, there remains a gap in applying these interoceptive insights to enhance assistive technologies such as brain-computer interfaces (BCIs). In the context of BCIs, motor imagery (MI) --the mental rehearsal of movement--serves as a widely used control paradigm, yet its modulation through the cardiac cycle has not been empirically tested. Bridging this gap, this study examined how the cardiac cycle phases influence MI by assessing their effect on contralateral suppression of alpha (8-13 Hz) and beta (14-30 Hz) activity in primary sensorimotor cortices. Materials & MethodsTwenty-nine participants performed left/right thumb abductions based on the direction of an arrow presented on the screen to get familiarised with kinesthetic sensations. They then completed a MI task of the same movements. We recorded both electroencephalography (EEG) and electrocardiography (ECG), focusing our analysis on data epochs aligned with the experimental cue, based on whether it occurred during the systolic or diastolic phase of the cardiac cycle. Time-frequency analysis of source-reconstructed data assessed cue-induced changes in power spectral density (PSD) within the alpha and beta bands in the postcentral and precentral gyrus. ResultsWe found that alpha and beta suppression in the contralateral primary motor and somatosensory cortex was more pronounced when the cue fell during the diastolic phase of the cardiac cycle than during the systolic phase. Validating the main results, an analysis with circular statistics revealed that trials with particularly pronounced contralateral alpha and beta suppression featured cues with latencies clustering during diastole, the quietest time of the cardiac cycle. Accompanying the EEG effects, EMG activity on the side of the movement was enhanced during diastole. ConclusionThese findings provide evidence that MI performance can be enhanced by considering the cardiac cycle phases, offering promising implications for BCI-based applications. O_LIKey point 1: The phases of the cardiac cycle influence motor imagery performance. C_LIO_LIKey point 2: Alpha and beta contralateral suppression over sensorimotor cortices is more pronounced when movement direction is cued during diastole. C_LIO_LIKey point 3: Contralateral suppression is more likely to cluster during the quietest time of the diastolic phase: between the T-wave and the P-wave. C_LI

neuroscience↗

bioRxiv2023

Dearth of smoking-induced mutations in oncogene-driven non-small-cell lung cancer despite smoking exposure

Non-small cell lung cancers (NSCLCs) in non-smokers are mostly driven by mutations in the oncogenes EGFR, ERBB2, and MET, and fusions involving ALK and RET. We term these "non-smoking-related oncogenes" (NSROs). In addition to occurring in non-smokers, NSRO-driven tumors also occur in smokers, and the clonal architecture and genomic landscape of these tumors remain unknown. We investigated genomic and transcriptomic alterations in 173 tumor sectors from 48 patients with NSRO-driven or typical-smoking NSCLCs. NSRO-driven NSCLCs in smokers and non-smokers have similar genomic landscapes. Surprisingly, even in patients with prominent smoking histories, the mutational signature caused by tobacco smoking was essentially absent in NSRO-driven NSCLCs. However, NSRO-driven NSCLCs in smokers had higher transcriptomic activities related to regulation of the cell cycle, suggesting that smoking still affects tumor phenotype independently of genomic alterations. Statement of significanceThis study highlights the lack of genomic scars caused by smoking in NSCLCs driven by non-smoking-related oncogenes regardless of smoking history. The impact of smoking on these tumors is mainly non-genomic. The transcriptomic features of NSCLCs associated with smoking may help in the development of therapeutic approaches.

cancer biology↗

bioRxiv2022

A SI3-sigma; arch stabilizes cyanobacteria transcription initiation complex

Multi-subunit RNA polymerases (RNAPs) associate with initiation factors ({sigma} in bacteria) to start transcription. The {sigma} factors are responsible for recognizing and unwinding promoter DNA in all bacterial RNAPs. Here, we report two cryo-EM structures of cyanobacterial transcription initiation complexes at near-atomic resolutions. The structures show that cyanobacterial RNAP forms an SI3-{sigma} arch interaction between domain 2 of {sigma}A ({sigma}2) and the sequence insertion 3 (SI3) in the mobile catalytic domain Trigger Loop (TL). The SI3-{sigma} arch facilitates transcription initiation from promoters of different classes through sealing the main cleft and thereby stabilizing RNAP-promoter DNA open complex. Disruption of the SI3-{sigma} arch disturbs cyanobacteria growth and stress response. Our study reports the structure of cyanobacterial RNAP and unique mechanism for its transcription initiation. Our data suggest functional plasticity of SI3 and provide foundation for further research into cyanobacteria and chloroplasts transcription.

biochemistry↗

bioRxiv2021

Cell transcriptomic atlas of the non-human primate Macaca fascicularis

Studying tissue composition and function in non-human primates (NHP) is crucial to understand the nature of our own species. Here, we present a large-scale single-cell and single-nucleus transcriptomic atlas encompassing over one million cells from 43 tissues from the adult NHP Macaca fascicularis. This dataset provides a vast, carefully annotated, resource to study a species phylogenetically close to humans. As proof of principle, we have reconstructed the cell-cell interaction networks driving Wnt signalling across the body, mapped the distribution of receptors and co-receptors for viruses causing human infectious diseases and intersected our data with human genetic disease orthologous coordinates to identify both expected and unexpected associations. Our Macaca fascicularis cell atlas constitutes an essential reference for future single-cell studies in human and NHP.

cell biology↗

bioRxiv2019

Diagnostic value of galactomannan in bronchoalveolar lavage fluid for chronic respiratory disease with pulmonary aspergillosis

ObjectiveTo explore the diagnostic value of the bronchoalveolar lavage fluid galactomannan (BALF GM) test for chronic respiratory disease with pulmonary aspergillosis, and establish the optimal cut-off value.\n\nMethodsA total of 180 chronic respiratory disease patients seen at the Respiratory Medicine Department of Peking University Shenzhen Hospital from September 2017 to September 2018 were analyzed. According to the diagnostic criteria, we divided the patients into the case group (n = 70, comprising 5, 20, and 45 proven, probable, and possible cases, respectively) and the control group (n = 110). Bronchoalveolar lavage fluid was collected, and the BALF GM test results were analyzed.\n\nResultsA non-parametric rank-sum test showed that the mean rank of the case group was 140.80, which was higher than that of the control group (58.49). The Z-value was 10.335 (P = 0.000), indicating that the general distribution of BALF GM differed between the two groups. A BALF GM cut-off value of 0.485 showed the highest diagnostic efficacy for pulmonary aspergillosis. The sensitivity, specificity, positive predictive value, and negative predictive value were 92.9%, 100%, 92.8%, and 100%, respectively. As the cut-off value increased, the specificity and sensitivity of the BALF GM test increased and decreased, respectively.\n\nConclusionsThe BALF GM test can be used confirm the diagnosis of patients with pulmonary aspergillosis and chronic respiratory disease. The optimum BALF GM cut-off value was 0.485. Antifungal therapy is important for treating pulmonary aspergillus infection in patients with chronic respiratory disease.

microbiology↗