Biology subjects

Jia, K.

Publications and source records attributed to Jia, K..

26 records · Page 2Linked to original sources

bioRxiv2022

New Functions Identified for HIV gp120 with the New ProtSub Sequence Matching

The reduced cost of sequencing is leading to an explosive growth in the number of available sequences across diverse genomes, and for individual patients. Inferring meaningful functions of individual genes/proteins is lagging, which hinders the deeper understanding of biological function and evolution. Traditionally, protein function has been determined by time consuming experimental methods or by sequence matching that often does not agree with the experimental findings. We have significantly improved protein sequence matching, by accounting for inter-dependent amino acid substitutions observed within densely packed protein structures, which yields additional substitutions beyond those usually seen, with good matches to additional proteins, some having new functions, not identified by conventional sequence matching. In the current study, we have applied this approach to predict novel functions for the proteins from HIV. These newly found functional annotations are then manually reviewed and many are validated from the literature, here for the HIV envelope protein gp120. These new functions are both more specific as well as some being entirely novel functions. We also show statistically that on average our new functional annotations are more informative than those given by conventional substitution matrices such as BLOSUM62. These results suggest that the new ProtSub protein sequence matching that incorporates structural information generally yields better identifications of related proteins, which can have broader and often gains in identifying more specific functions

bioinformatics↗

bioRxiv2020

Phage Peptides Mediate Precision Base Editing with Focused Targeting Window

Cytidine base editors (CBE) are novel genome engineering tools that can generate C-to-T nucleotide substitutions without introducing double-stranded breaks (DSBs). Instead of generating single-point mutations, CBEs induce nucleotide substitutions at wobble positions within the 20-nucleotide target site. A variety of strategies have been developed to improve the targeting scope and window of CBEs. Among these strategies, molecular switches that can temporally control CBE activities represent compelling options. In this study, we investigated the feasibility of using a bacteriophage-derived peptide, referred to as G8PPD, as the off-switch of CBEs. We showed that G8PPD could be employed to control the activities of and improve the targeting window of A3A and BE3 CBEs and adenine base editor 7.10 (ABE7.10). Notably, in a cell-based disease model of Marfan syndrome, G8PPD facilitated A3A CBE-based gene correction with a more focused targeting window and improved the percentage of perfectly edited gene alleles from less than 4% to more than 38% of the whole population. Our study presents the first peptide off-switch that can improve the targeting scope of CBEs, thus highlighting the importance of the temporal control of BE activity for precision base editing.

genomics↗

bioRxiv2020

Experience-dependent alteration of mnemonic representation in early visual cortex and intraparietal sulcus

The ability to discriminate between stimuli relies on a chain of neural operations associated with perception, memory and decision-making. Accumulating studies show learning-dependent plasticity in perception or decision-making, yet whether perceptual learning modifies mnemonic processing remains unclear. Here, we trained participants on an orientation discrimination task, while using fMRI and TMS to separately examine training-induced changes in working memory (WM) representation. Although fMRI decoding revealed orientation-specific neural patterns during delay period in early visual cortex (V1) before, but not after, training, neurodisruption of V1 during delay period led to behavioral deficit in both phases. In contrast, both fMRI decoding and disruptive effect of TMS showed that intraparietal sulcus (IPS) represent WM content after, but not before, training. These results suggest that sensory engagement for WM is relatively independent of training but the coding format may be altered, whereas the involvement of parietal area in WM depends on training.

neuroscience↗

bioRxiv2020

RPRH: a web-based tool for the inference of potential roles of plant microRNAs in human body

Recently, increasing studies reported that plant microRNAs (miRNAs) from food could be absorbed through gastrointestinal tract to regulate the physiological processes of animals. These novel cross-kingdom regulatory roles of plant miRNAs open a new field in miRNA study and drug discovery, but the lack of corresponding bioinformatics tools limit the development of this field. In this study, we built a web-based tool, RPRH (Role of Plant microRNA in Human), to infer the potential roles of plant miRNAs in human and to profile the landscape of all documented plant miRNAs regulatory functions in human. Totally, RPRH included 10414 miRNAs from 82 plant species and 18062 annotation terms like diseases, pathway, gene ontology (GO), and drugs. RPRH represents a bioinformatics resource for further investigation of cross-kingdom regulations of plant miRNAs. Availabilityhttp://www.rnanut.net/rprh/

bioinformatics↗

bioRxiv2020

Recurrent plasticity mechanisms for perceptual decisions in the human brain

Learning and experience are critical for translating ambiguous sensory information from our environments to perceptual decisions. Yet, evidence on how training molds the adult human brain remains controversial, as fMRI at standard resolution does not allow us to discern the finer-scale mechanisms that underlie sensory plasticity. Here, we combine ultra-high field (7T) functional imaging at sub-millimetre resolution with orientation discrimination training to interrogate experience-dependent plasticity across cortical depths. Our results provide evidence for recurrent plasticity, by contrast to sensory encoding vs. feedback mechanisms. We demonstrate that learning alters orientation-specific representations in superficial rather than middle V1 layers, suggesting changes in read-out rather than input signals. Further, learning increases feedforward rather than feedback layer-to-layer connectivity in occipito-parietal regions, suggesting that sensory plasticity gates perceptual decisions. Our findings propose finer-scale plasticity mechanisms that re-weight sensory signals to inform improved decisions, bridging the gap between micro- and macro-circuits of experience-dependent plasticity.

neuroscience↗

bioRxiv2020

Suppressive recurrent and feedback computations for adaptive processing in the human brain

Adapting to the environment statistics by reducing brain responses to repetitive sensory information is key for efficient information processing. Yet, the fine-scale computations that support this adaptive processing in the human brain remain largely unknown. Here, we capitalize on the sub-millimetre resolution afforded by ultra-high field imaging to examine BOLD-fMRI signals across cortical depth and discern competing hypotheses about the brain mechanisms (feedforward vs. feedback) that mediate adaptive visual processing. We demonstrate suppressive recurrent processing within visual cortex, as indicated by stronger BOLD decrease in superficial than middle and deeper layers for gratings that were repeatedly presented at the same orientation. Further, we show dissociable connectivity mechanisms for adaptive processing: enhanced feedforward connectivity within visual cortex, while feedback occipito-parietal connectivity, reflecting top-down influences on visual processing. Our findings provide evidence for a circuit of local recurrent and feedback interactions that mediate rapid brain plasticity for adaptive information processing.

neuroscience↗

bioRxiv2018

Anchorene is an endogenous diapocarotenoid required for anchor root formation in Arabidopsis

Arabidopsis root development is predicted to be regulated by yet unidentified carotenoid-derived metabolite(s). In this work, we screened known and putative carotenoid cleavage products and identified anchorene, a predicted carotenoid-derived dialdehyde (diapocarotenoid) that triggers anchor root development. Anchor roots are the least characterized type of root in Arabidopsis. They form at the root-shoot junction, particularly upon damage to the root apical meristem. Using Arabidopsis reporter lines, mutants and chemical inhibitors, we show that anchor roots originate from pericycle cells and that the development of this root type is auxin-dependent and requires carotenoid biosynthesis. Transcriptome analysis and treatment of auxin-reporter lines indicate that anchorene triggers anchor root development by modulating auxin homeostasis. Exogenous application of anchorene restored anchor root development in carotenoid-deficient plants, indicating that this compound is the carotenoid-derived signal required for anchor root development. Chemical modifications of anchorene led to a loss of anchor root promoting activity, suggesting that this compound is highly specific. Furthermore, we demonstrate by LC-MS analysis that anchorene is a natural, endogenous Arabidopsis metabolite. Taken together, our work reveals a new member of the family of carotenoid-derived regulatory metabolites and hormones.\n\nSignificanceUnknown carotenoid-derived compounds are predicted to regulate different aspects of plant development. Here, we characterize the development of anchor roots, the least characterized root type in Arabidopsis, and show that this process depends on auxin and requires a carotenoid-derived metabolite. We identified a presumed carotenoid-derivative, anchorene, as the likely, specific signal involved in anchor root formation. We further show that anchorene is a natural metabolite that occurs in Arabidopsis. Based on the analysis of auxin reporter lines and transcriptome data, we provide evidence that anchorene triggers the growth of anchor roots by modulating auxin homeostasis. Taken together, our work identifies a novel carotenoid-derived growth regulator with a specific developmental function.

plant biology↗

bioRxiv2018

SeqStruct : A New Amino Acid Similarity Matrix Based on Sequence Correlations and Structural Contacts Yields Sequence-Structure Congruence

Protein sequence matching does not properly account for some well-known features of protein structures: surface residues being more variable than core residues, the high packing densities in globular proteins, and does not yield good matches of sequences of many proteins known to be close structural relatives. There are now abundant protein sequences and structures to enable major improvements to sequence matching. Here, we utilize structural frameworks to mount the observed correlated sequences to identify the most important correlated parts. The rationale is that protein structures provide the important physical framework for improving sequence matching. Combining the sequence and structure data in this way leads to a simple amino acid substitution matrix that can be readily incorporated into any sequence matching. This enables the incorporation of allosteric information into sequence matching and transforms it effectively from a 1-D to a 3-D procedure. The results from testing in over 3,000 sequence matches demonstrate a 37% gain in sequence similarity and a loss of 26% of the gaps when compared with the use of BLOSUM62. And, importantly there are major gains in the specificity of sequence matching across diverse proteins. Specifically, all known cases where protein structures match but sequences do not match well are resolved.

bioinformatics↗