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Growth hormone (GH) receptor (GHR) mutations give rise to GH-resistance (Laron syndrome). We previously treated GH-resistant Ghr-/- mice (Laron mice) with adeno-associated virus (AAV) delivering mouse (m)Ghr controlled by a constitutively active liver-specific promoter (HLP). A single injection of AAV-HLP-mGHR resulted in a significant but limited increase in body length and weight, consistent with studies of IGF-1 treatment in humans and mice. Here, we performed RNA-seq on male and female mouse livers comprising the following groups: GHR+/+ (wild-type), GHR-/- (Laron), AAV-HLP-mGHR-treated GHR-/- (treatment group), and AAV-HLP-Luc (Luciferase)-treated GHR-/- (control group). Only four genes showed significant differential expression in GHR -/- mouse liver following Luciferase vector treatment, indicating minimal effect of the AAV-HLP vector. AAV-HLP-mGHR stimulated significant expression changes in 448 genes compared to AAV-HLP-Luc control, substantially fewer than the 2781 genes whose expression was altered in GHR-/- compared to GHR+/+. AAV-HLP-mGHR treatment induced the GH-responsive IGF signaling genes Igf1 and Igfals ~16-fold compared to AAV-HLP-Luc control, but only to 40–45% of GHR+/+ liver levels. The treatment also upregulated a small subset of genes beyond GHR+/+ expression levels (p-adj 0.05), including the proto-oncogenes Ascl1 , Tmprss4 , and others. Finally, genes dysregulated upon GHR loss and upregulated in livers of AAV-HLP-mGHR-treated mice were significantly enriched for sex-biased genes, consistent with the major role of GH and GHR in regulating liver sex differences. While gene replacement therapy is a potential therapy for Laron syndrome, an unregulated constitutively active promoter may drive unexpected and unbalanced changes in liver gene expression that will require monitoring.
Tay et al. (Thu,) studied this question.