ECEESPE2025 Rapid Communications Rapid Communications 14: Growth Axis and Syndromes (6 abstracts)
Unexpected unbalanced upregulation of genes in gene replacement therapy with a constitutively active promoter and growth hormone receptor (GHR) in mice with nonfunctional GHR (laron mice)
Kok Onn Lee 1 , Joshua Tay 1 , Kian Sia 1 , Siti Rodhi 1 , Shu Gan 1 , Zhen Fu 1 , Max Pyatkov 2 , John Kopchick 3 , Michael Waters 4 & David Waxman 2
1National University of Singapore, Medicine, Singapore, Singapore; 2Boston University, Boston, United States; 3Ohio University, Athens, United States; 4University of Queensland, Institute for Molecular Bioscience, Brisbane, Australia
JOINT2695
Gene replacement therapy where a dysfunctional or non-functional gene is treated with in vivo delivery of a functional gene almost always utilizes a constitutively active promoter/enhancer to enable expression of the therapeutic gene product. These promoters typically lack the complex regulation that is normally present in the endogenous gene. We have treated growth hormone (GH) resistant dwarf GHR-/- (Laron) mice with nonfunctional GH-receptors, with an adeno-associated virus (AAV) with a constitutively liver specific promoter (HLP) and mouse GHR (Sia et al, 2021). A single injection of the AAV-HLP-GHR construct resulted in significant but limited increase in length and weight, of a similar order to previously reported studies of IGF-1 treatment in mice or human Laron syndrome. In the present study, we have compared the total gene expresssion profiles from the mice in that previous study. Profiles of total RNA extracted from fresh frozen livers from the 4 groups of mice (3 male and 3 female in each group) were sequenced (Novogene-AIT Genomics, Singapore) and compared: Untreated GHR+/+, and GHR-/- (Laron); GHR-/- treated with AAV-HLP-GHR (AAV-GHR), and control GHR-/- treated with AAV-HLP-luciferase (AAV-luc) only. Gene expression differed significantly in only 4 genes comparing control AAV-luc and untreated GHR-/- (Laron), indicating minimal effect of the AAV-HLP promoter. Gene expression between GHR+/+ and GHR-/- (Laron) differed significantly in 2913 genes. In contrast, treatment with AAV-GHR compared with AAV-luc showed that only 448 genes were differentially expressed significantly. There was significant upregulation of key genes involved in IGF signaling; GHR, insulin-like growth factor-1 (IGF-1) and acid-labile subunit (ALS). However, of the significant upregulated 201 genes in AAV-GHR compared to AAV-luc, growth/cancer-related genes were upregulated/rescued significantly more than metabolism-related genes towards the normal gene expression levels in the wild type mice (GHR+/+). This unexpected unbalance upregulation is most probably the result of the absence of the normal complex regulation of the GH-receptor.
Conclusion: Gene replacement therapy utilizing a consitutively active promoter/enhancer may have unexpected unbalanced changes in gene expression.
Volume 110
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Endocrine Abstracts
ISSN 1470-3947 (print) | ISSN 1479-6848 (online)
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