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The Role of Human Antigen R (HuR) in Pathological Cardiac Remodeling

Green, Lisa
http://orcid.org/0000-0002-1164-6611
http://rave.ohiolink.edu/etdc/view?acc_num=ucin1649769228853118

Abstract Details

2022, PhD, University of Cincinnati, Medicine: Molecular, Cellular and Biochemical Pharmacology.
Heart failure is one of the leading causes of death globally, and the function of a failing heart is often worsened by the presence of pathological cardiac hypertrophy and fibrosis. RNA-binding proteins (RBPs) are gaining interest as emerging players in the mechanisms of adverse cardiac remodeling and can exert affect broad effects on the transcriptome through RNA splicing and stabilization/destabilization of target RNA transcripts. HuR (HuR; gene name ELAVL1) is a ubiquitously expressed RBP that is highly expressed in multiple cell types in the heart, although little is known about its physiological function. Immunohistochemistry of HuR expression in the myocardium indicates that HuR expression is increased in failing human hearts. Using a pressure-overload model of heart failure (Transverse Aortic Constriction, TAC), these studies demonstrate that a cardiomyocyte-specific deletion of HuR, as well as pharmacological inhibition of HuR, are cardioprotective in preserving cardiac function and decreasing cardiac fibrosis post-TAC. Interestingly, global pharmacological inhibition of HuR in every cell type within the heart, produced a much stronger dampening of adverse cardiac remodeling than the cardiomyocyte-specific knockout. This indicates that HuR could be modulating remodeling in cell types other than cardiac myocytes. Therefore, the follow-up studies went on to assess the role of HuR in cardiac fibroblasts in vitro. Using isolated primary mouse cardiac fibroblasts and a series of myofibroblast activation assays including scratch assays, collagen gel contraction assays, and picrosirius staining, these studies determined that HuR is necessary for fibroblast activation and myofibroblast activity. In order to determine which directly-bound RNA targets of HuR are important in fibroblasts activation, a photoactivatable ribonucleoside-enhanced crosslinking and immunoprecipitation (PAR-CLIP) was performed to identify mRNA transcripts that were enriched for HuR binding following TGFb treatment and myofibroblast activation. One of the most significant HuR-bound targets that was upregulated with myofibroblast activation was Wnt-inducible signaling protein-1 (Wisp1; gene name Ccn4). Wisp1 also significantly correlated with HuR and two well-known markers of fibroblast activation, periostin and aSMA, in a single-cell RNA sequencing database of fibroblasts isolated from the ischemic zone. Further studies determined that the upregulation of Wisp1 downstream of TGFb treatment is HuR-dependent. Finally, addition of exogenous recombinant Wisp1 is able to partially rescue myofibroblast contractile function following HuR inhibition, demonstrating that HuR-dependent Wisp1 expression plays a functional role in HuR-dependent myofibroblast activity downstream of TGFb. This further supports that HuR activity is necessary for the functional activation of primary cardiac fibroblasts in response to TGFb, in part through post-transcriptional regulation of Wisp1. In summary, these studies demonstrate a functional role for HuR in the progression of pressure overload–induced cardiac hypertrophy and strengthen HuR inhibition as a viable therapeutic approach for decreasing pathological cardiac hypertrophy, fibrosis, and decline to heart failure. These studies also give insight into important downstream targets that may play an important role in regulation of cardiac remodeling, such as Wisp1.
Michael Tranter, Ph.D. (Committee Member)
Onur Kanisicak, PhD (Committee Member)
Thomas Thompson, Ph.D. (Committee Member)
Sakthivel Sadayappan, Ph.D. (Committee Member)
Jo El Schultz, Ph.D. (Committee Member)
Evangelia Kranias, Ph.D. (Committee Member)
167 p.
Organismal Biology
Cardiac fibrosis; HuR; fibroblast; RNA binding protein; Cardiac hypertrophy; Wisp1

Recommended Citations

Citations

  • Green, L. (2022). The Role of Human Antigen R (HuR) in Pathological Cardiac Remodeling [Doctoral dissertation, University of Cincinnati]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1649769228853118

    APA Style (7th edition)

  • Green, Lisa. The Role of Human Antigen R (HuR) in Pathological Cardiac Remodeling. 2022. University of Cincinnati, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=ucin1649769228853118.

    MLA Style (8th edition)

  • Green, Lisa. "The Role of Human Antigen R (HuR) in Pathological Cardiac Remodeling." Doctoral dissertation, University of Cincinnati, 2022. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1649769228853118

    Chicago Manual of Style (17th edition)

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This open access ETD is published by University of Cincinnati and OhioLINK.