Biology subjects

Zheng, K.

Publications and source records attributed to Zheng, K..

7 recordsLinked to original sources

bioRxiv2018

Osteoblastic PLEKHO1 contributes to joint inflammation in rheumatoid arthritis

Osteoblasts participating in the inflammation regulation gradually obtain concerns. However, its role in joint inflammation of rheumatoid arthritis (RA) is largely unknown. Pleckstrin homology domain-containing family O member 1 (PLEKHO1) was previously identified as a negative regulator of osteogenic lineage activity. Here we demonstrated that PLEKHO1 was highly expressed in osteoblasts of articular specimens from RA patients and inflammatory arthritis mice. Genetic deletion of osteoblastic Plekho1 ameliorated joint inflammation in mice with collagen-induced arthritis (CIA) and K/BxN serum-transfer arthritis (STA), whereas overexpressing Plekho1 only within osteoblasts in CIA and STA mice demonstrated exacerbated local inflammation. Further in vitro studies indicated that PLEKHO1 was required for TRAF2-mediated RIP1 ubiquitination to activate NF-kB for inducing inflammatory cytokines production in osteoblasts. Moreover, osteoblastic PLEKHO1 inhibition improved joint inflammation and attenuated bone formation reduction in CIA mice and non-human primate arthritis model. These data strongly suggest that highly expressed PLEKHO1 in osteoblast mediates joint inflammation in RA. Targeting osteoblastic PLEKHO1 may exert dual therapeutic action of alleviating joint inflammation and promoting bone formation in RA.

cell biology↗

bioRxiv2018

Astroglia withdraw from potentiated synapses boosting inter-synaptic cross-talk

Extrasynaptic actions of glutamate are limited by high-affinity transporters on perisynaptic astroglial processes (PAPs), which helps to maintain point-to-point transmission in excitatory circuits. Memory formation in the brain is associated with synaptic remodelling, but how this remodelling affects PAPs and therefore extrasynaptic glutamate actions is poorly understood. Here we used advanced imaging methods, in situ and in vivo, to find that a classical synaptic memory mechanism, long-term potentiation (LTP), triggers withdrawal of PAPs from potentiated synapses. Optical glutamate sensors combined with patch-clamp and 3D molecular localisation reveal that LTP induction thus prompts a spatial retreat of glial glutamate transporters, boosting glutamate spillover and NMDA receptor-mediated inter-synaptic cross-talk. The LTP-triggered PAP withdrawal involves NKCC1 transporters and the actin-controlling protein cofilin but does not depend on major Ca2+-dependent cascades in astrocytes. We have therefore uncovered a mechanism by which synaptic potentiation could alter signal handling by multiple nearby connections.

neuroscience↗

bioRxiv2018

Multiplexed calcium imaging of single-synapse activity and astroglial responses in the intact brain

All-optical registration of neuronal and astrocytic activities within the intact mammalian brain has improved significantly with recent advances in optical sensors and biophotonics. However, relating single-synapse release events and local astroglial responses to sensory stimuli in an intact animal has not hitherto been feasible. Here, we present a multiplexed multiphoton excitation imaging approach for assessing the relationship between presynaptic Ca2+ entry at thalamocortical axonal boutons and perisynaptic astrocytic Ca2+ elevations, induced by whisker stimulation in the barrel cortex of C57BL/6 mice. We find that, unexpectedly, Ca2+ elevations in the perisynaptic astrocytic regions consistently precede local presynaptic Ca2+ signals during spontaneous brain activity associated with anaesthesia. The methods described here can be adapted to a variety of optical sensors and are compatible with experimental designs that might necessitate repeated sampling of single synapses over a longitudinal behavioural paradigm.\n\nHighlightsO_LIWe applied multiplexed multiphoton imaging to optically assess activity of individual synapses and the surrounding astroglia in the intact brain\nC_LIO_LIPerisynaptic astrocytic regions display localiased, context-dependent Ca2+ elevations in vivo\nC_LIO_LISuch elevations may precede spontaneous Ca2+ entry at presynaptic boutons\nC_LIO_LIThis method paves the way for optical investigation of glutamate release probability in vivo\nC_LI

neuroscience↗

bioRxiv2018

Multiplex imaging of quantal glutamate release and presynaptic Ca2+ at multiple synapses in situ

Information processing by brain circuits depends on Ca2+-dependent, stochastic release of the excitatory neurotransmitter glutamate. Recently developed optical sensors have enabled detection of evoked and spontaneous release at common glutamatergic synapses. However, monitoring synaptic release probability, its use-dependent changes, and its underpinning presynaptic machinery in situ requires concurrent, intensity-independent readout of presynaptic Ca2+ and glutamate release. Here, we find that the red-shifted Ca2+ indicator Cal-590 shows Ca2+-sensitive fluorescence lifetime, and employ it in combination with the novel green glutamate sensor SF-iGluSnFR variant to document quantal release of glutamate together with presynaptic Ca2+ concentration, in multiple synapses in an identified neural circuit. At the level of individual presynaptic boutons, we use multi-exposure and stochastic reconstruction procedures to reveal nanoscopic co-localisation of presynaptic Ca2+ entry and glutamate release, a fundamental unknown in modern neurobiology. This approach opens a new horizon in the quest to understand release machinery of central synapses.

neuroscience↗

bioRxiv2018

Changes in neuronal immunofluorescence in the C- versus N-terminal domains of hnRNP H following D1 dopamine receptor activation

RNA binding proteins are a diverse class of proteins that regulate all aspects of RNA metabolism. Accumulating studies indicate that heterogeneous nuclear ribonucleoproteins are associated with cellular adaptations in response to drugs of abuse. We recently mapped and validated heterogeneous nuclear ribonucleoprotein H1 (Hnrnph1) as a quantitative trait gene underlying differential behavioral sensitivity to methamphetamine. The molecular mechanisms by which hnRNP H1 alters methamphetamine behaviors are unknown but could involve preand/or post-synaptic changes in protein localization and function. Methamphetamine initiates post-synaptic D1 dopamine receptor signaling indirectly by binding to pre-synaptic dopamine transporters and vesicular monoamine transporters of midbrain dopaminergic neurons which triggers revers e transport and accumulation of dopamine at the synapse. Here, we examined changes in neuronal localization of hnRNP H in primary rat cortical neurons that express dopamine receptors that can be modulated by the D1 or D2 dopamine receptor agonists SKF38393 and (-)-Quinpirole HCl, respectively. Basal immunostaining of hnRNP H was localized primarily to the nucleus. D1 dopamine receptor activation induced an increase in hnRNP H nuclear immunostaining as detected by immunocytochemistry with a C-domain directed antibody containing epitope near the glycine-rich domain but not with an N-domain specific antibody. Although there was no change in hnRNP H protein in the nucleus or cytoplasm, there was a decrease in Hnrnph1 transcript following D1 receptor stimulation. Taken together, these results suggest that D1 receptor activation increases availability of the hnRNP H C-terminal epitope, which could potentially reflect changes in protein-protein interactions. Thus, D1 receptor signaling could represent a key molecular post-synaptic event linking Hnrnph1 polymorphisms to drug-induced behavior.\n\nHighlightsO_LIWe investigated immunofluorescence and localization of hnRNP H following dopamine receptor activation in primary rat cortical neurons.\nC_LIO_LIActivation of D1 dopamine receptor increased nuclear immunofluorescence of the C-terminal domain but not the N-terminal domain of hnRNP H with no change in either nuclear or cytoplasmic levels of hnRNP H protein.\nC_LIO_LID1 dopamine signaling could alter interaction of hnRNP H with other proteins.\nC_LI

neuroscience↗

bioRxiv2017

Rice TSV3 Encoding Obg-like GTPase Protein is Essential for Chloroplast Development during the Early Leaf Stage under Cold Stress

The Spo0B-associated GTP-binding (Obg) proteins occupy a wide variety of roles in the viability of nearly all bacteria. Its detailed roles in higher plants have not yet been elucidated. A novel rice thermo-sensitive virescent mutant tsv3 was identified in this study that displayed albino phenotype at 20{degrees}C before the 3-leaf stage while being normal green at 32{degrees}C or even at 20{degrees}C after the 4-leaf stage. The mutant phenotype was aligned with altered chlorophyll (Chl) content and chloroplast development. Map-based cloning and complementation test showed that TSV3 encoded a kind of small GTP binding protein. Subcellular localization revealed that TSV3 was in chloroplast. TSV3 transcripts were highly expressed in leaves and weak or undetectable in other tissues, suggesting the tissue-specific expression. In tsv3 mutant, the transcriptional levels of certain genes associated with biogenesis of chloroplast ribosomes 50S subunit were severely decreased at the 3-leaf-stage under cold stress, but could be recovered to normal levels at a higher temperature (32{degrees}C). The observations from this study indicated that the rice nuclear-encoded TSV3 plays important roles in chloroplast development at early leaf stage under cold stress.

plant biology↗

bioRxiv2016

Cas13b is a Type VI-B CRISPR-associated RNA-Guided RNase differentially regulated by accessory proteins Csx27 and Csx28

CRISPR-Cas adaptive immune systems defend microbes against foreign nucleic acids via RNA-guided endonucleases. Using a computational sequence database mining approach, we identify two Class 2 CRISPR-Cas systems (subtype VI-B) that lack Cas1 and Cas2 and encompass a single large effector protein, Cas13b, along with one of two previously uncharacterized associated proteins, Csx27 or Csx28. We establish that these CRISPR-Cas systems can achieve RNA interference when heterologously expressed. Through a combination of biochemical and genetic experiments, we show that Cas13b processes its own CRISPR array with short and long direct repeats, cleaves target RNA, and exhibits collateral RNase activity. Using an E. coli essential gene screen, we demonstrate that Cas13b has a double-sided protospacer-flanking sequence and elucidate RNA secondary structure requirements for targeting. We also find that Csx27 represses, whereas Csx28 enhances, Cas13b-mediated RNA interference. Characterization of these CRISPR systems creates opportunities to develop tools to manipulate and monitor cellular transcripts.

microbiology↗