Biology subjects

Peng, B.

Publications and source records attributed to Peng, B..

At least 55 records · Page 3Linked to original sources

bioRxiv2022

Autofluorescence is a biomarker of neural stem cell activation state

Neural stem cells (NSCs) in the adult brain are primarily quiescent but can activate and enter the cell cycle to produce newborn neurons. NSC quiescence can be regulated by disease, injury, and age, however our understanding of NSC quiescence is limited by technical limitations imposed by the bias of markers used to isolate each population of NSCs and the lack of live-cell labeling strategies. Fluorescence lifetime imaging (FLIM) of autofluorescent metabolic cofactors has previously been used in other cell types to study shifts in cell states driven by metabolic remodeling that change the optical properties of these endogenous fluorophores. Here we asked whether autofluorescence could be used to discriminate NSC activation state. We found that quiescent NSCs (qNSCs) and activated NSCs (aNSCs) each have unique autofluorescence intensity and fluorescence lifetime profiles. Additionally, qNSCs specifically display an enrichment of a specific autofluorescent signal localizing to lysosomes that is highly predictive of cell state. These signals can be used as a graded marker of NSC quiescence to predict cell behavior and track the dynamics of quiescence exit at single cell resolution in vitro and in vivo. Through coupling autofluorescence imaging with single-cell RNA sequencing in vitro and in vivo, we provide a high-resolution resource revealing transcriptional features linked to rapid NSC activation and deep quiescence. Taken together, we describe a single-cell resolution, non-destructive, live-cell, label-free strategy for measuring NSC activation state in vitro and in vivo and use this tool to expand our understanding of adult neurogenesis.

neuroscience↗

bioRxiv2022

ExposomeX: Integrative Exposomic Platform Expediates Discovery of "Exposure-Biology-Disease" Nexus

Exposome has become the hotspot of next-generation health studies. To date, there is no available effective platform to standardize the analysis of exposomic data. In this study, we aim to propose one new framework of exposomic analysis and build up one novel integrated platform "ExposomeX" to expediate the discovery of the "Exposure-Biology-Disease" nexus. We have developed 13 standardized modules to accomplish six major functions including statistical learning (E-STAT), exposome database search (E-DB), mass spectrometry data processing (E-MS), meta-analysis (E-META), biological link via pathway integration and protein-protein interaction (E-BIO) and data visualization (E-VIZ). Using ExposomeX, we can effectively analyze the multiple-dimensional exposomics data and investigate the "Exposure-Biology-Disease" nexus by exploring mediation and interaction effects, understanding statistical and biological mechanisms, strengthening prediction performance, and automatically conducting meta-analysis based on well-established literature databases. The performance of ExposomeX has been well validated by re-analyzing two previous multi-omics studies. Additionally, ExposomeX can efficiently help discover new associations, as well as relevant in-depth biological pathways via protein-protein interaction and gene ontology network analysis. In sum, we have proposed a novel framework for standardized exposomic analysis, which can be accessed using both R and online interactive platform (http://www.exposomex.cn/).

bioinformatics↗

bioRxiv2022

Synthetic in vivo compartmentalisation improves metabolic flux and modulates the product profile of promiscuous enzymes

Enzyme spatial organisation and compartmentalisation are naturally evolved mechanisms for facilitating multi-step biocatalysis. We explored the synthetic in vivo co-encapsulation of two different cargo proteins in yeast using a self-assembling virus-like particle. Co-encapsulation was verified using single particle techniques for both end-to-end fusion of the cargo proteins with the encapsulation anchor at one end, and coexpression of each cargo protein with their individual anchors. The co-encapsulation of a bifunctional geranyl diphosphate/farnesyl diphosphate synthase and a bifunctional linalool/nerolidol synthase delivered nerolidol titres up to 30 times that of an unorganised free enzyme control, a remarkable improvement from a single engineering step. Interestingly, striking differences in the ratio of products (linalool and nerolidol) were observed with each spatial organisation approach. This work presents the largest reported titre fold increases from in vivo enzyme compartmentalisation and suggests that enzyme spatial organisation could be used to modulate the product profile of promiscuous enzymes.

synthetic biology↗

bioRxiv2022

Translational fusion of terpene synthases enhances metabolic flux by increasing protein stability

The end-to-end fusion of enzymes that catalyse successive steps in a reaction pathway is a metabolic engineering strategy that has been successfully applied in a variety of pathways and is particularly common in terpene bioproduction. Despite its popularity, limited work has been done to interrogate the mechanism of metabolic enhancement from enzyme fusion. We observed a remarkable >110-fold improvement in nerolidol production upon translational fusion of nerolidol synthase (a sesquiterpene synthase) to farnesyl diphosphate synthase. This delivered a titre increase from 29.6 mg/L up to 4.2 g/L nerolidol in a single engineering step. Whole-cell proteomic analysis revealed that nerolidol synthase levels in the fusion strains were greatly elevated compared to the non-fusion control. Similarly, the fusion of nerolidol synthase to non-catalytic domains also produced comparable increases in titre, which coincided with improved enzyme expression. When farnesyl diphosphate synthase was fused to other terpene synthases, we observed more modest improvements in terpene titre (1.9- and 3.8-fold), which corresponds to increases of a similar magnitude in terpene synthase expression. Therefore, increased in vivo enzyme levels - resulting from improved expression and/or stability - is likely to be a major driver of catalytic enhancement from enzyme fusion.

synthetic biology↗

bioRxiv2022

Engineering a plant polyketide synthase for the biosynthesis of methylated flavonoids

Homoeriodictyol and hesperetin are naturally occurring O-methylated flavonoids with many health-promoting properties. They are produced in plants in low abundance and as complex mixtures of similar compounds that are difficult to separate. Synthetic biology offers the opportunity to produce various flavonoids in a targeted, bottom-up approach in engineered microbes with high product titers. However, the production of O-methylated flavonoids is currently still highly inefficient. In this study, we investigated and engineered a combination of enzymes that had previously been shown to support homoeriodictyol and hesperetin production in Escherichia coli from fed O-methylated cinnamic acids. We determined the crystal structures of the enzyme catalyzing the first committed step of the pathway, chalcone synthase from Hordeum vulgare, in three ligand-bound states. Based on these structures and a multiple sequence alignment with other chalcone synthases, we constructed mutant variants and assessed their performance in E. coli towards producing methylated flavonoids. With our best mutant variant, HvCHS (Q232P, D234V), we were able to produce homoeriodictyol and hesperetin at 2 times and 10 times higher titers than previously reported. Our findings will facilitate the further engineering of this enzyme towards higher production of methylated flavonoids.

biochemistry↗

bioRxiv2022

PLK1 O-GlcNAcylation is essential for dividing mammalian cells and inhibits uterine carcinoma

The O-linked N-acetylglucosamine (O-GlcNAc) transferase (OGT) mediates intracellular O-GlcNAcylation modification, whose function and substrates have entranced biologists and chemists alike. O-GlcNAcylation occurs on Ser/Thr residues and takes part in a vast array of physiological processes. OGT is essential for dividing mammalian cells, and it underscores many human diseases. Yet many of its fundamental substrates in the cell division process remains to be unveiled. Here we focus on its effect on Polo-like kinase 1 (PLK1), a mitotic master kinase that governs DNA replication, mitotic entry, chromosome segregation and mitotic exit. We found that PLK1 interacts with OGT and is O-GlcNAcylated. By utilizing stepped collisional energy/higher-energy collisional dissociation (sceHCD) mass spectrometry (MS) and mutagenesis studies, the critical O-GlcNAc site is located to be Thr291. Interestingly, T291N is a uterine carcinoma mutant in the TCGA database. Biochemical assays show that T291A and T291N both increase PLK1 stability. Using stable H2B-GFP cells, we show that PLK1-T291A and -T291N mutants display chromosome segregation defects, and result in misaligned and lagging chromosomes. In mouse xenograft models, we demonstrate that the O-GlcNAc-deficient PLK1-T291A and -T291N mutants would enhance uterine carcinoma in animals. Hence, we propose that OGT partially exerts its mitotic function through O-GlcNAcylation of PLK1, and sceHCD MS might be a new method to reveal many more O-GlcNAcylation substrates.

cancer biology↗

bioRxiv2022

Individual differences in oxycodone addiction-like behaviors in a large cohort of heterogeneous stock (HS) rats

Family and twin studies demonstrate that genetic factors determine 20-60% of the vulnerability to opioid use disorder. However, the genes/alleles that mediate the risk of developing addiction-related behaviors, including the sensitivity to the analgesic efficacy of opioids, the development of tolerance, dependence, and escalation of oxycodone taking and seeking, have been ill-defined, thus hindering efforts to design pharmacological interventions to enable precision medicine strategies. Here we characterized oxycodone addiction-like behaviors in heterogeneous stock (HS) rats, that show high genetic diversity that mimics the high genetic variability in humans. HS rats were allowed to self-administer oxycodone for two h/daily for four days (ShA) and then moved to 12h/daily (LgA) for 14 days. Animals were screened for motivation to self-administer oxycodone using a progressive-ratio (PR) schedule of reinforcement and for the development of withdrawal-induced hyperalgesia and tolerance to the analgesic effects of oxycodone using the von-Frey and tail immersion tests, respectively. To reduce cohort-specific effects, we used cohorts of 46-60 rats and normalized the response level within cohorts using a Z-score. To take advantage of the four opioid-related behaviors and further identify subjects that are consistently vulnerable vs. resilient to compulsive oxycodone use, we computed an Addiction Index by averaging normalized responding (Z-scores) for the four behavioral tests. Results showed high individual variability between vulnerable and resilient rats, likely to facilitate the detection of gene variants associated with vulnerable vs. resilient individuals. Such data will have considerable translational value for designing follow-up studies in humans.

neuroscience↗

bioRxiv2022

Functional autapses form in striatal parvalbumin interneurons but not medium spiny neurons

Autapses (or self-synapses) selectively form in specific cell types in many brain regions including the neocortex and the hippocampus, where they provide feedback control over self-spiking activities. Previous morphological studies also found putative autapses in medium spiny neurons (MSNs) of the striatum. However, it remains unclear whether striatal neurons indeed form physiologically functional autapses. We performed whole-cell recordings from striatal neurons in acute mouse brain slices, and identify autaptic neurons by the occurrence of prolonged asynchronous release (AR) of neurotransmitter after high-frequency burst of action potentials (APs) in the same cell. To our surprise, we found no autaptic release in all recorded MSNs after the AP burst, even in the presence of Sr2+ that should desynchronize and thus prolong synaptic vesicle release. In sharp contrast, we observed robust autaptic AR events in half of the recorded parvalbumin (PV)-positive neurons. Autaptic responses in PV cells were mediated by GABAA receptors, and the AR strength was dependent on the frequency and the number of APs during the burst. Further simulation results show that autapses regulate burst spiking in PV cells by providing self-inhibition and thus shape network oscillation at certain frequencies. Together, we reveal that, distinct from MSNs, striatal PV neurons form functional autapses, activation of which would regulate self-activities in PV cells, and thereby shape MSN firing and network oscillations. Author summarySynapses, which usually occur between two neurons, are key structures for signal communication in the nervous system. However, some types of neurons form autapses, where a neuron synapses onto itself. Autaptic transmission provides feedback signal regulating self-spiking activities. Neuronal and network activities in the striatum play critical roles in motor control and other brain functions. Previous studies suggest formation of autapses in striatal principal MSNs, but it remains unclear whether striatal neurons form functional autapses. We performed direct recordings from striatal neurons and examined the occurrence of autaptic transmission in acute brain slices. Surprisingly, we did not detect any autaptic responses in MSNs. A large proportion of striatal PV neurons, however, produced robust autaptic GABA release upon high-frequency stimulation, indicating selective formation of autapses in striatal PV cells. Our computation simulations suggest that autapses provide self-inhibition in PV cells and thereby shape activities in MSNs and striatal network, particularly when PV cells discharge at high frequencies corresponding to a high dopamine state. Together, our findings indicate that PV cells, but not MSNs, in the striatum form physiologically functional autapses. Autapses in PV cells could be essential circuit elements in the striatum and contribute to striatal functions, such as motor control.

neuroscience↗

bioRxiv2021

The m6A reader YTHDF2 is a negative regulator for dendrite development and maintenance of retinal ganglion cells

The precise control of growth and maintenance of the retinal ganglion cell (RGC) dendrite arborization is critical for normal visual functions in mammals. However, the underlying mechanisms remain elusive. Here we find that the m6A reader YTHDF2 is highly expressed in the mouse RGCs. Conditional knockout (cKO) of Ythdf2 in the retina leads to increased RGC dendrite branching, resulting in more synapses in the inner plexiform layer. Interestingly, the Ythdf2 cKO mice show improved visual acuity compared with control mice. We further demonstrate that Ythdf2 cKO in the retina protects RGCs from dendrite degeneration caused by the experimental acute glaucoma model. We identify the m6A-modified YTHDF2 target transcripts which mediate these effects. This study reveals mechanisms by which YTHDF2 restricts RGC dendrite development and maintenance. YTHDF2 and its target mRNAs might be valuable in developing new treatment approaches for glaucomatous eyes. Impact statementThe m6A reader YTHDF2 negatively regulates RGC dendrite branching through destabilizing its m6A-modified target mRNAs encoding proteins controlling dendrite development and maintenance. Ythdf2 cKO improves visual acuity and alleviates acute ocular hypertension-induced glaucoma in mice.

neuroscience↗

bioRxiv2021

Cell-state specific aggresome formation in fibroblasts is driven by stress-activated MAPK signaling

The aggresome is a protein turnover system in which proteins are trafficked along microtubules to the centrosome for degradation. Despite extensive focus on aggresomes in immortalized cell lines, it remains unclear if the aggresome is conserved in all primary cells and all cell-states. Here we examined the aggresome in primary adult mouse dermal fibroblasts shifted into four distinct cell-states. We found that in response to proteasome inhibition, quiescent and immortalized fibroblasts formed aggresomes whereas proliferating and senescent fibroblasts did not. Using this model, we generated a resource to better understand the aggresome, providing a characterization of the proteostasis networks in which the aggresome is used and transcriptomic features associated with the presence or absence of aggresome formation. Using this resource, we validate a previously reported role for p38 MAPK signaling in aggresome formation and identify TAK1 as a novel driver of aggresome formation upstream of p38 MAPKs. Together, our data demonstrate that the aggresome is a non-universal protein degradation system which can be used cell-state specifically and provide a resource for better understanding aggresome formation and function.

cell biology↗

bioRxiv2021

Molecular basis for SPINDOC-Spindlin1 engagement and its role in transcriptional inhibition

Spindlin1 is a transcriptional coactivator with three Tudor-like domains, of which the first and second Tudors are engaged in histone methylation readout, while the function of the third Tudor is largely unknown. Recent studies revealed that the transcriptional co-activator activity of Spindlin1 could be attenuated by SPIN*DOC. Here we solved the crystal structure of SPIN*DOC-Spindlin1 complex, revealing that a hydrophobic motif, DOCpep3 (256-281), of SPIN*DOC interacts with Tudor 3 of Spindlin1 and completes its {beta}-barrel fold. Massive hydrophobic contacts and hydrogen bonding interactions ensure a high affinity DOCpep3-Spindlin1 engagement with a binding Kd of 30 nM. Interestingly, we characterized two more K/R-rich motifs of SPIN*DOC, DOCpep1 (187-195) and DOCpep2 (228-239), which bind to Spindlin1 at lower affinities with Kd values of 78 M and 31 M, respectively. Structural and binding studies revealed that DOCpep1 and DOCpep2 competitively bind to the aromatic cage of Spindlin1 Tudor 2 that is responsible for H3K4me3 readout. Although DOCpep3-Spindlin1 engagement is compatible with histone readout, an extended SPIN*DOC fragment containing DOCpep1 and DOCpep2 inhibits histone or TCF4 binding by Spindin1 due to introduced competition. This inhibitory effect is more pronounced for weaker binding targets but not for strong ones such as H3 "K4me3-K9me3" bivalent mark. Our RT-qPCR experiment showed that the removal of the hydrophobic motif or the K/R-rich region compromised the inhibitory effects of SPIN*DOC on Spindlin1-mediated transcriptional activation. In sum, here we revealed multivalent engagement between SPIN*DOC and Spindlin1, in which a hydrophobic motif acts as the primary binding site for stable SPIN*DOC-Spindlin1 association, while two more neighboring K/R-rich motifs further modulate the target selectivity of Spindlin1 via competitive inhibition, therefore attenuating the transcriptional co-activator activities of Spindlin1 through affecting its chromatin association.

biophysics↗

bioRxiv2021

Robust T1 MRI cortical surface pipeline for neonatal brain and systematic evaluation using multi-site MRI datasets

The human brain grows the most dramatically during the perinatal and early postnatal periods, during which preterm birth or perinatal injury that may alter brain structure and lead to developmental anomalies. Thus, characterizing cortical thickness of developing brains remains an important goal. However, this task is often complicated by inaccurate cortical surface extraction due to small-size brains. Here, we propose a novel complex framework for the reconstruction of neonatal WM and pial surfaces, accounting for large partial volumes due to small-size brains. The proposed approach relies only on T1-weighted images unlike previous T2-weighted image-based approaches while only T1-weighted images are sometimes available under the different clinical/research setting. Deep neural networks are first introduced to the neonatal MRI pipeline to address the mis-segmentation of brain tissues. Furthermore, this pipeline enhances cortical boundary delineation using combined models of the CSF/GM boundary detection with edge gradient information and a new skeletonization of sulcal folding where no CSF voxels are seen due to the limited resolution. We also proposed a systematic evaluation using three independent datasets comprising 736 preterm and 97 term neonates. Qualitative assessment for reconstructed cortical surfaces shows that 86.9% are rated as accurate across the three site datasets. In addition, our landmark-based evaluation shows that the mean displacement of the cortical surfaces from the true boundaries was less than a voxel size (0.532{+/-}0.035mm). Evaluating the proposed pipeline (namely NEOCIVET 2.0) shows the robustness and reproducibility across different sites and different age-groups. The mean cortical thickness measured positively correlated with postmenstrual age (PMA) at scan (p<0.0001); Cingulate cortical areas grew the most rapidly whereas the inferior temporal cortex grew the least rapidly. The range of the cortical thickness measured was biologically congruent (1.3mm at 28 weeks of PMA to 1.8mm at term equivalent). Cortical thickness measured on T1 MRI using NEOCIVET 2.0 was compared with that on T2 using the established dHCP pipeline. It was difficult to conclude that either T1 or T2 imaging is more ideal to construct cortical surfaces. NEOCIVET 2.0 has been open to the public through CBRAIN (https://mcin-cnim.ca/technology/cbrain/), a web-based platform for processing brain imaging data.

bioinformatics↗

bioRxiv2020

The mouse cortico-basal ganglia-thalamic network

The cortico-basal ganglia-thalamic loop is one of the fundamental network motifs in the brain. Revealing its structural and functional organization is critical to understanding cognition, sensorimotor behavior, and the natural history of many neurological and neuropsychiatric diseases. Classically, the basal ganglia is conceptualized to contain three primary information output channels: motor, limbic, and associative. However, given the roughly 65 cortical areas and two dozen thalamic nuclei that feed into the dorsal striatum, a three-channel view is overly simplistic for explaining the myriad functions of the basal ganglia. Recent works from our lab and others have subdivided the dorsal striatum into numerous functional domains based on convergent and divergent inputs from the cortex and thalamus. To complete this work, we generated a comprehensive data pool of [~]700 injections placed across the striatum, external globus pallidus (GPe), substantia nigra pars reticulata (SNr), thalamic nuclei, and cortex. We identify 14 domains of SNr, 36 in the GPe, and 6 in the parafascicular and ventromedial thalamic nuclei. Subsequently, we identify 6 parallel cortico-basal ganglia-thalamic subnetworks that sequentially transduce specific subsets of cortical information with complex patterns of convergence and divergence through every elemental node of the entire cortico-basal ganglia loop. These experiments reveal multiple important novel features of the cortico-basal ganglia network motif. The prototypical sub-network structure is characterized by a highly interconnected nature, with cortical information processing through one or more striatal nodes, which send a convergent output to the SNr and a more parallelized output to the GPe; the GPe output then converges with the SNr. A domain of the thalamus receives the nigral output, and is interconnected with both the striatal domains and the cortical areas that filter into its nigral input source. This study provides conceptual advancement of our understanding of the structural and functional organization of the classic cortico-basal ganglia network.

neuroscience↗

bioRxiv2020

Reduction of neuronal activity mediated by blood-vessel regression in the brain

The brain vasculature supplies neurons with glucose and oxygen, but little is known about how vascular plasticity contributes to brain function. Using longitudinal in vivo imaging, we reported that a substantial proportion of blood vessels in the adult brain sporadically occluded and regressed. Their regression proceeded through sequential stages of blood-flow occlusion, endothelial cell collapse, relocation or loss of pericytes, and retraction of glial endfeet. Regressing vessels were found to be widespread in mouse, monkey and human brains. Both brief occlusions of the middle cerebral artery and lipopolysaccharide-mediated inflammation induced an increase of vessel regression. Blockage of leukocyte adhesion to endothelial cells alleviated LPS-induced vessel regression. We further revealed that blood vessel regression caused a reduction of neuronal activity due to a dysfunction in mitochondrial metabolism and glutamate production. Our results elucidate the mechanism of vessel regression and its role in neuronal function in the adult brain.

neuroscience↗

bioRxiv2020

Goslin - A Grammar of Succinct Lipid Nomenclature

We introduce Goslin, a polyglot grammar for common lipid shorthand nomenclatures based on the LipidMaps nomenclature and the shorthand nomenclature established by Liebisch et al. and used by LipidHome and SwissLipids. Goslin was designed to address the following pressing issues in the lipidomics field: 1) to simplify the implementation of lipid name handling for developers of mass spectrometry-based lipidomics tools; 2) to offer a tool that unifies and normalizes the main existing lipid name dialects enabling a lipidomics analysis in a high-throughput fashion. We provide implementations of Goslin in four major programming languages, namely C++, Java, Python 3, and R to kick-start adoption and integration. Further, we set up a web service for users to work with Goslin directly. All implementations are available free of charge under a permissive open source license.

bioinformatics↗

bioRxiv2020

Differential Expression and Interaction network construction of Noncoding RNA and mRNA in Heart Tissue associated with Tetralogy of Fallot

Tetralogy of Fallot (TOF) is still the most common and complicated cyanotic congenital heart defect of all congenital heart diseases with a 10% incidence. Surgery repair is often necessary in infancy. The etiology of TOF is complex and genetic and epigenetic mechanisms such as chromosomal abnormalities, gene mutations, nucleic acid modifications, non-coding RNA, and circular RNA(circRNA) play an important role in its occurrence. RNA not only plays an auxiliary role of genetic information carrier, but also plays a more important role in various regulatory functions. There are few studies on the action mechanism of non-coding RNA. Aim to gain more in-depth knowledge of TOF, we collected tissue samples of the right ventricular outflow tract of 5 TOF children with no other intracardiac and extracardiac malformations and 5 normal fetuses. We systematically analyzed the specific long non-coding RNA (lncRNA), microRNA(miRNA), circRNA and messenger RNA(mRNA) profiles of TOF. To our knowledge, there are no reports of genome-wide study of transcriptome in TOF and we first obtained meaningful differentially expressed lncRNAs, miRNAs, circle RNA and mRNAs.

genetics↗

bioRxiv2020

Anacardic acid protects against phenylephrine-induced mouse cardiac hypertrophy through JNK signaling-dependent regulation of histone acetylation

Cardiac hypertrophy is a complex process induced by the activation of multiple signaling pathways. We previously reported that anacardic acid (AA), a histone acetylase (HAT) inhibitor, attenuates phenylephrine (PE)-induced cardiac hypertrophy by downregulating histone H3 acetylation at lysine 9 (H3K9ac). Unfortunately, the upstream signaling events remained unknown. The mitogen-activated protein kinase (MAPK) pathway is an important regulator of cardiac hypertrophy. In this study, we explored the role of JNK/MAPK signaling in cardiac hypertrophy. A mouse model of cardiomyocyte hypertrophy was successfully established in vitro using PE. This study showed that p-JNK directly interacts with HATs (P300 and P300/CBP-associated factor, PCAF) and alters H3K9ac. In addition, both the JNK inhibitor SP600125 and the HAT inhibitor AA attenuated p-JNK overexpression and H3K9 hyperacetylation by inhibiting P300 and PCAF during PE-induced cardiomyocyte hypertrophy. Moreover, we demonstrated that both SP600125 and AA attenuate the overexpression of cardiac hypertrophy-related genes (MEF2A, ANP, BNP, and {beta}-MHC), preventing cardiomyocyte hypertrophy and dysfunction. These results revealed a novel mechanism through which AA might protect mice from PE-induced cardiac hypertrophy. In particular, AA inhibits the effects of JNK signaling on HAT-mediated histone acetylation, and could therefore be used to prevent and treat hypertrophic cardiomyopathy.

cell biology↗

bioRxiv2020

A synergistic action of sirtuins directly recognizes DNA breaks and potentiates DNA damage response and repair

The DNA damage response (DDR) is a highly orchestrated process but how double-strand DNA breaks (DSBs) are initially recognized is unclear. Here, we show that polymerized SIRT6 deacetylase recognizes DSBs and potentiates the DDR. First, SIRT1 deacetylates SIRT6 at residue K33, which is important for SIRT6 polymerization and mobilization toward DSBs. Then, K33-deacetylated SIRT6 anchors to {gamma}H2AX, allowing its retention on and subsequent remodeling of local chromatin. We show that a K33R mutation that mimics hypoacetylated SIRT6 can rescue defective DNA repair as a result of SIRT1 deficiency in cultured cells. These data highlight the synergistic action between SIRTs in the spatiotemporal regulation of the DDR and DNA repair.

biochemistry↗