Abstract 254: Profiling Transcriptional Changes and Identifying Novel Molecular Markers During the Dedifferentiation of Cardiomyocyte

The loss of cardiomyocytes (CMs) during heart failure (HF) cannot be replaced by new CMs due to their limited proliferative capacity. Regenerating the failing heart by promoting CM cell-cycle re-entry has thus become a possible solution rigorously pursued. Some genes have been proven to promote endogenous CM proliferation, nearly always preceded by CM dedifferentiation, wherein terminally-differentiated CMs are reversed back initially to a less-matured status, preceding cell division. However, very little else is known about CM dedifferentiation, including the lack of robust molecular markers, the mechanisms driving it, whether it necessarily leads to CM proliferation, and the effect of CM dedifferentiation alone on cardiac function. Therefore, investigating CM dedifferentiation is of great significance. Here, we profiled genome-wide transcriptional changes and identified novel molecular markers during CM dedifferentiation. We used the established in vitro model where adult mouse CMs dedifferentiated and re-differentiated (DR) upon 2-week long culture, without detectable cell division. DR was evident by breakdown and rebuilding of sarcomeres, and differential regulation of cardiac fetal genes. Tracking the transcriptome change pointed to gene pathways involved in this process and potential markers of CM dedifferentiation. Another assumption is that transient induction of Yamanaka factors ( Oct4, Sox2, Klf4, Myc, OSKM ) induces CM dedifferentiation of CMs in vivo , since the four factors are themselves sufficient to induce pluripotency of human and mouse somatic cells. Our preliminary results show that CM-specific overexpression of OSKM using adeno-associated virus serotype 9 (AAV9) induced fetal-like hallmarks, down-regulation of sarcomeric genes, re-activation of cell cycle, reduced fatty acid utilization, and associated loss of cardiac function . Putative markers identified in the in vitro model was also validated to be upregulated in OSKM -overexpressed CMs. In conclusion, through 2 models of CM dedifferentiation, we have screened out potential novel markers and regulators of CM dedifferentiation which now requires further validation.

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Abstract 14391: Transient Cell Cycle Induction in Cardiomyocytes is a Promising Approach to Treat Ischemia Induced Heart Failure

Circulation ◽

10.1161/circ.142.suppl_3.14391 ◽

2020 ◽

Vol 142 (Suppl_3) ◽

Author(s):

Riham Abouleisa ◽

Qinghui Ou ◽

Xian-liang Tang ◽

Mitesh Solanki ◽

Yiru Guo ◽

...

Keyword(s):

Cell Cycle ◽

Cardiac Function ◽

Single Cell ◽

Ischemia Reperfusion Injury ◽

Ischemia Reperfusion ◽

Cardiomyocyte Proliferation ◽

Specific Expression ◽

Control Virus

Rationale: The regenerative capacity of the heart to repair itself after myocardial infarction (MI)is limited. Our previous study showed that ectopic introduction of Cdk1/CyclinB1 andCdk4/CyclinD1 complexes (4F) promotes cardiomyocyte proliferation in vitro and in vivo andimproves cardiac function after MI. However, its clinical application is limited due to the concernsfor tumorigenic potential in other organs. Objectives: To first, identify on a single cell transcriptomic basis the necessary reprogrammingsteps that cardiomyocytes need to undertake to progress through the proliferation processfollowing 4F overexpression, and then, to determine the pre-clinical efficacy of transient andcardiomyocyte specific expression of 4F in improving cardiac function after MI in small and largeanimals. Methods and Results: Temporal bulk and single cell RNAseq of mature hiPS-CMs treated with4F or LacZ control for 24, 48, or 72 h revealed full cell cycle reprogramming in 15% of thecardiomyocyte population which was associated with sarcomere disassembly and metabolicreprogramming. Transient overexpression of 4F specifically in cardiomyocytes was achievedusing non-integrating lentivirus (NIL) driven by TNNT2 (TNNT2-4F-NIL). One week after inductionof ischemia-reperfusion injury in rats or pigs, TNNT2-4F-NIL or control virus was injectedintramyocardially. Compared with controls, rats or pigs treated with TNNT2-4F-NIL showed a 20-30% significant improvement in ejection fraction and scar size four weeks after treatment, asassessed by echocardiography and histological analysis. Quantification of cardiomyocyteproliferation in pigs using a novel cytokinesis reporter showed that ~10% of the cardiomyocyteswithin the injection site were labelled as daughter cells following injection with TNNT2-4F-NILcompared with ~0.5% background labelling in control groups. Conclusions: We provide the first understanding of the process of forced cardiomyocyteproliferation and advanced the clinical applicability of this approach through minimization ofoncogenic potential of the cell cycle factors using a novel transient and cardiomyocyte-specificviral construct.

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The 37/67-Kilodalton Laminin Receptor Is a Receptor for Adeno-Associated Virus Serotypes 8, 2, 3, and 9

Journal of Virology ◽

10.1128/jvi.00878-06 ◽

2006 ◽

Vol 80 (19) ◽

pp. 9831-9836 ◽

Cited By ~ 264

Author(s):

Bassel Akache ◽

Dirk Grimm ◽

Kusum Pandey ◽

Stephen R. Yant ◽

Hui Xu ◽

...

Keyword(s):

Gene Therapy ◽

Cultured Cells ◽

Human Gene ◽

Laminin Receptor ◽

Transduction Efficiency ◽

Adeno Associated Virus ◽

Virus Serotype ◽

Tumor Gene

ABSTRACT Adeno-associated virus serotype 8 (AAV8) is currently emerging as a powerful gene transfer vector, owing to its capability to efficiently transduce many different tissues in vivo. While this is believed to be in part due to its ability to uncoat more readily than other AAV serotypes such as AAV2, understanding all the processes behind AAV8 transduction is important for its application and optimal use in human gene therapy. Here, we provide the first report of a cellular receptor for AAV8, the 37/67-kDa laminin receptor (LamR). We document binding of LamR to AAV8 capsid proteins and intact virions in vitro and demonstrate its contribution to AAV8 transduction of cultured cells and mouse liver in vivo. We also show that LamR plays a role in transduction by three other closely related serotypes (AAV2, -3, and -9). Sequence and deletion analysis allowed us to map LamR binding to two protein subdomains predicted to be exposed on the AAV capsid exterior. Use of LamR, which is constitutively expressed in many clinically relevant tissues and is overexpressed in numerous cancers, provides a molecular explanation for AAV8's broad tissue tropism. Along with its robust transduction efficiency, our findings support the continued development of AAV8-based vectors for clinical applications in humans, especially for tumor gene therapy.

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314. Pristimerin Enhances Recombinant Adeno-Associated Virus Serotype 2 Vector-Mediated Transgene Expression Both In Vitro and In Vivo

Molecular Therapy ◽

10.1016/s1525-0016(16)34649-4 ◽

2013 ◽

Vol 21 ◽

pp. S121

Keyword(s):

Transgene Expression ◽

Adeno Associated Virus ◽

Virus Serotype

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115. Bio-Engineering of Adeno-Associated Virus Serotype (AAV)-2 Capsid at Serine/Threonine Residues Improves Its Transduction Efficiency Both In Vitro and In Vivo

Molecular Therapy ◽

10.1016/s1525-0016(16)35919-6 ◽

2012 ◽

Vol 20 ◽

pp. S47-S48

Keyword(s):

Transduction Efficiency ◽

Adeno Associated Virus ◽

Virus Serotype ◽

Bio Engineering

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A RAD9-dependent cell cycle arrest in response to unresolved recombination intermediates in Saccharomyces cerevisiae

10.1101/736850 ◽

2019 ◽

Author(s):

Hardeep Kaur ◽

GN Krishnaprasad ◽

Michael Lichten

Keyword(s):

Saccharomyces Cerevisiae ◽

Cell Cycle ◽

Dna Damage ◽

Cell Division ◽

Cell Cycle Arrest ◽

Mitotic Cell ◽

Cycle Arrest ◽

Associated Lesions

AbstractIn Saccharomyces cerevisiae, the conserved Sgs1-Top3-Rmi1 helicase-decatenase regulates homologous recombination by limiting accumulation of recombination intermediates that are precursors of crossovers. In vitro studies have suggested that the dissolution of double-Holliday junction joint molecules by Sgs1-driven convergent junction migration and Top3-Rmi1 mediated strand decatenation could be responsible for this. To ask if dissolution occurs in vivo, we conditionally depleted Sgs1 and/or Rmi1 during return to growth, a procedure where recombination intermediates formed during meiosis are resolved when cells resume the mitotic cell cycle. Sgs1 depletion during return to growth delayed joint molecule resolution, but ultimately most were resolved and cells divided normally. In contrast, Rmi1 depletion resulted in delayed and incomplete joint molecule resolution, and most cells did not divide. rad9Δ mutation restored cell division in Rmi1-depleted cells, indicating that the DNA damage checkpoint caused this cell cycle arrest. Restored cell division in rad9Δ, Rmi1-depleted cells frequently produced anucleate cells, consistent with the suggestion that persistent recombination intermediates prevented chromosome segregation. Our findings indicate that Sgs1-Top3-Rmi1 acts in vivo, as it does in vitro, to promote recombination intermediate resolution by dissolution. They also indicate that, in the absence of Top3-Rmi1 activity, unresolved recombination intermediates persist and activate the DNA damage response, which is usually thought to be activated by much earlier DNA damage-associated lesions.

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Nestin promotes pulmonary fibrosis via facilitating recycling of TGF-β receptor I

European Respiratory Journal ◽

10.1183/13993003.03721-2020 ◽

2021 ◽

pp. 2003721

Author(s):

Jiancheng Wang ◽

Xiaofan Lai ◽

Senyu Yao ◽

Hainan Chen ◽

Jianye Cai ◽

...

Keyword(s):

Pulmonary Fibrosis ◽

Critical Role ◽

Intermediate Filament Protein ◽

Nestin Expression ◽

Adeno Associated Virus ◽

Intratracheal Administration ◽

Virus Serotype ◽

Fibrotic Lung Disease

Idiopathic pulmonary fibrosis (IPF) is a progressive fibrotic lung disease that is characterised by aberrant proliferation of activated myofibroblasts and pathological remodelling of the extracellular matrix. Previous studies have revealed that the intermediate filament protein Nestin plays key roles in tissue regeneration and wound healing in different organs. Whether Nestin plays a critical role in the pathogenesis of IPF needs to be clarified.Nestin expression in lung tissues from bleomycin-treated mice and IPF patients was determined. Transfection with Nestin shRNA vectors in vitro that regulated TGF-β/Smad signalling was conducted. Biotinylation assays to observe plasma membrane TβRI, TβRI endocytosis and TβRI recycling after Nestin knockdown were performed. Adeno-associated virus serotype 6 (AAV6)-mediated Nestin knockdown was assessed in vivo.We found that Nestin expression was increased in a murine pulmonary fibrosis model and IPF patients, and that the upregulated protein primarily localised in lung α-SMA+ myofibroblasts. Mechanistically, we determined that Nestin knockdown inhibited TGF-β signalling by suppressing recycling of TβRI to the cell surface and that Rab11 was required for the ability of Nestin to promote TβRI recycling. In vivo, we found that intratracheal administration of adeno-associated virus serotype 6 (AAV6)-mediated Nestin knockdown significantly alleviated pulmonary fibrosis in multiple experimental mice models.In conclusion, our findings reveal a pro-fibrotic function of Nestin partially through facilitating Rab11-dependent recycling of TβRI and shed new light on pulmonary fibrosis treatment.

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