Figure 1 - available via license: Creative Commons Attribution 4.0 International
Content may be subject to copyright.
Generation of Phosphorylase kinase beta deficient mouse. (A) Schematic representation of the Phkb-knockout and WT alleles. Deletion of 329 bp of exon 4 and flanking sequence of the phosphorylase kinase beta (Phkb) gene generates Phkb-knockout allele without exon 4. Arrows indicate the primer set used for genotyping. (B) PCR amplification of two PCR fragments, 485 bp and 156 bp in length amplified genomic DNA of Phkb −/− and WT (Phkb +/+ ). (C) Relative mRNA expression (Fold change) of phosphorylase kinase beta subunit gene (Phkb) in wild-type (n = 5; WT, white bar) and Phkb −/− (n = 11, grey bar) mice. (D) Representative images of livers (WT, left; Phkb −/− right). (E) Mean
Source publication
Glycogen storage disease type IX (GSD-IX) constitutes nearly a quarter of all GSDs. This ketotic form of GSD is caused by mutations in phosphorylase kinase (PhK), which is composed of four subunits (α, β, γ, δ). PhK is required for the activation of the liver isoform of glycogen phosphorylase (PYGL), which generates free glucose-1-phosphate monomer...
Contexts in source publication
Context 1
... analysis confirmed the expected deletion of 329 bp of exon 4 of the Phkb gene ( Figure 1A,B). Generation of Phkb −/− knockout mice exhibited no clear variation in physical growth or appearance compared to WT or heterozygous mice (data not shown). ...
Context 2
... of Phkb −/− knockout mice exhibited no clear variation in physical growth or appearance compared to WT or heterozygous mice (data not shown). Relative mRNA expression of the Phkb gene was later confirmed by real-time qPCR ( Figure 1C) in Phkb −/− mice. We observed Phkb −/− mice displayed hepatomegaly ( Figure 1D) with elevated liver weight/body weight (LW/BW) percentages (7.57%) compared to WT (5.38%) mice ( Figure 1E). ...
Context 3
... mRNA expression of the Phkb gene was later confirmed by real-time qPCR ( Figure 1C) in Phkb −/− mice. We observed Phkb −/− mice displayed hepatomegaly ( Figure 1D) with elevated liver weight/body weight (LW/BW) percentages (7.57%) compared to WT (5.38%) mice ( Figure 1E). No significant differences were observed in body weight or appearance between Phkb −/− and WT mice (data not shown). ...
Context 4
... mRNA expression of the Phkb gene was later confirmed by real-time qPCR ( Figure 1C) in Phkb −/− mice. We observed Phkb −/− mice displayed hepatomegaly ( Figure 1D) with elevated liver weight/body weight (LW/BW) percentages (7.57%) compared to WT (5.38%) mice ( Figure 1E). No significant differences were observed in body weight or appearance between Phkb −/− and WT mice (data not shown). ...
Context 5
... analysis confirmed the expected deletion of 329 bp of exon 4 of the Phkb gene ( Figure 1A,B). Generation of Phkb −/− knockout mice exhibited no clear variation in physical growth or appearance compared to WT or heterozygous mice (data not shown). ...
Context 6
... of Phkb −/− knockout mice exhibited no clear variation in physical growth or appearance compared to WT or heterozygous mice (data not shown). Relative mRNA expression of the Phkb gene was later confirmed by real-time qPCR ( Figure 1C) in Phkb −/− mice. We observed Phkb −/− mice displayed hepatomegaly ( Figure 1D) with elevated liver weight/body weight (LW/BW) percentages (7.57%) compared to WT (5.38%) mice ( Figure 1E). ...
Context 7
... mRNA expression of the Phkb gene was later confirmed by real-time qPCR ( Figure 1C) in Phkb −/− mice. We observed Phkb −/− mice displayed hepatomegaly ( Figure 1D) with elevated liver weight/body weight (LW/BW) percentages (7.57%) compared to WT (5.38%) mice ( Figure 1E). No significant differences were observed in body weight or appearance between Phkb −/− and WT mice (data not shown). ...
Context 8
... mRNA expression of the Phkb gene was later confirmed by real-time qPCR ( Figure 1C) in Phkb −/− mice. We observed Phkb −/− mice displayed hepatomegaly ( Figure 1D) with elevated liver weight/body weight (LW/BW) percentages (7.57%) compared to WT (5.38%) mice ( Figure 1E). No significant differences were observed in body weight or appearance between Phkb −/− and WT mice (data not shown). ...
Context 9
... addition, Aldolase B (Aldob) showed elevation, but it was not significant while mG6pc expression was slightly decreased ( Figure 3A). Glycolysis ( Figure S1A) and glycogenolysis ( Figure S1B) related genes were not changed or slightly decreased except moderate increase in Pygl −/− . Lipogenesis, lipid degradation, and transcriptional regulation related genes were evaluated to investigate fatty acid metabolism. ...
Context 10
... addition, Aldolase B (Aldob) showed elevation, but it was not significant while mG6pc expression was slightly decreased ( Figure 3A). Glycolysis ( Figure S1A) and glycogenolysis ( Figure S1B) related genes were not changed or slightly decreased except moderate increase in Pygl −/− . Lipogenesis, lipid degradation, and transcriptional regulation related genes were evaluated to investigate fatty acid metabolism. ...
Context 11
... lipid degradation, and transcriptional regulation related genes were evaluated to investigate fatty acid metabolism. Although there were no significantly changed genes in WT or Phkb −/− mice, increased volatility was observed in Phkb −/− mice for fatty acid synthesis, degradation, transcriptional regulation, and transport related genes ( Figure S1C,D). mice. ...
Context 12
... Phkb −/− mice display increased mRNA levels of Ctgf, and Col1a1 at the 2 h fasted and nonfasted time points, respectively ( Figure 3B). In addition, investigation on profibrogenic and inflammation related gene showed no significant changes ( Figure S1E,F). , and Aldob), WT (0 h, n = 5, 2 h, n = 7, and 6 h, n = 5) and Phkb −/− (0 h, n = 11, 2 h, n = 6, and 6 h, n = 5) mice. ...
Context 13
... Phkb −/− mice display increased mRNA levels of Ctgf, and Col1a1 at the 2 h fasted and nonfasted time points, respectively ( Figure 3B). In addition, investigation on profibrogenic and inflammation related gene showed no significant changes ( Figure S1E,F). ...
Context 14
... Phkg2 −/− mice successfully recapitulated human GSD-IX-γ [21], here we characterized the metabolic abnormalities associated with GSD-IX-beta, utilizing a knockout mouse harboring a deficiency in the PHK beta subunit and studied its role in the underlying disease mechanism. Through phenotypical analysis, with hepatomegaly ( Figure 1C,D), sub-normal level of fasting glucose profile (Figure 2A), and significantly elevated blood ketone levels ( Figure 2B), we confirm that Phkb −/− mouse perfectly mimics GSD-IX-beta deficiency and it enabled further investigations to find disease mechanism underlying PHK-beta deficiency. ...
Context 15
... we have followed various aged Phkb −/− mice over 40 weeks to examine hepatic pathogenesis. In our observation, we found very minimal profibrogenic phenotypes in the group ( Figure 4C1-C4) while glycogen accumulation is similar or slightly higher in Phkb −/− mice ( Figure 2D). Gene expression analysis of fibrosis related genes showed increased Ctgf and Col1a1 genes at certain fasting times suggest Phkb −/− mice have less severe fibrogenic phenotypes parallel with GSD-IX-beta patients [1]. ...
Similar publications
Glycogen phosphorylase (GP) is biologically active as a dimer of identical subunits, each activated by phosphorylation of the serine-14 residue. GP exists in three interconvertible forms, namely GPa (di-phosphorylated form), GPab (mono-phosphorylated form), and GPb (non-phosphorylated form); however, information on GPab remains scarce. Given the pr...
Citations
... [121][122][123] A GSD IX β mouse model (C57BL/6NJ-Phkb em1(IMPC)J /Mmjax or Phkb À/À ) developed mild fasting hypoglycemia with elevated blood ketones in the fed and fasting state and histology revealed enlarged, glycogen-filled hepatocytes with minimal collagen deposition at 40 weeks of age. 59 ...
Glycogen storage disorders (GSDs) are inherited disorders of metabolism resulting from the deficiency of individual enzymes involved in the synthesis, transport, and degradation of glycogen. This literature review summarizes the development of gene therapy for the GSDs. The abnormal accumulation of glycogen and deficiency of glucose production in GSDs lead to unique symptoms based upon the enzyme step and tissues involved, such as liver and kidney involvement associated with severe hypoglycemia during fasting and the risk of long-term complications including hepatic adenoma/carcinoma and end stage kidney disease in GSD Ia from glucose-6-phosphatase deficiency, and cardiac/skeletal/smooth muscle involvement associated with myopathy +/- cardiomyopathy and the risk for cardiorespiratory failure in Pompe disease. These symptoms are present to a variable degree in animal models for the GSDs, which have been utilized to evaluate new therapies including gene therapy and genome editing. Gene therapy for Pompe disease and GSD Ia has progressed to Phase I and Phase III clinical trials, respectively, and are evaluating the safety and bioactivity of adeno-associated virus vectors. Clinical research to understand the natural history and progression of the GSDs provides invaluable outcome measures that serve as endpoints to evaluate benefits in clinical trials. While promising, gene therapy and genome editing face challenges with regard to clinical implementation, including immune responses and toxicities that have been revealed during clinical trials of gene therapy that are underway. This article is protected by copyright. All rights reserved.
Glycogen storage diseases (GSDs) are abnormally inherited glycogen metabolism mainly affecting the liver, muscles, and heart. Deficiency of proteins involved in glycogen metabolism caused by genetic mutations are responsible for different subtype of GSDs. However, there are still some challenges in diagnosing GSD. This study includes 39 suspected GSDs patients from unrelated families in China. Next‐generation sequencing (NGS) was used to investigate the reason for their diseases at the genetic level. Finally, all 39 patients were diagnosed with GSDs, including 20 GSD‐Ia, 4 GSD‐VI, and 15 GSD IX (12 GSD‐IXa patients and 3 GSD‐IXb patients). Thirty‐two mutations in G6PC1 , PYGL , PHKA2 , and PHKB genes were identified, with 14 of them being novel variants. The pathogenicity of novel variants was classified according to ACMG guildlines and predicted by in slico algorithms. Mutations p.L216L and p.R83H in G6PC1 gene may be the hot spot mutation in Chinese. Hearing impairment is a rare clinical feature of GSD Ia, which has also been observed in our cohort. The severity of GSD VI and IX was indicated by our patients. Close follow‐up should be applied to GSD VI and IX patients. Our findings provided evidence for building the phenotype–genotype of GSDs and expanded the mutation spectrum of related genes.
