AChR β-Subunit mRNAs Are Stabilized by HuR in a Mouse Model of Congenital Myasthenic Syndrome With Acetylcholinesterase Deficiency

Enhancing mRNA translation efficiency by introducing sequence optimized AU-rich elements in 3' UTR via HuR anchorage

mRNA technology holds immense promise as an innovative therapeutic approach with applications spanning infectious disease vaccines, cancer immunotherapy, protein replacement, and gene editing. However, practical use of mRNA has been hindered by challenges such as low cellular stability and transient protein expression. For addressing these, we propose a novel strategy to optimize mRNA sequences, particularly in the untranslated region, by inserting adenylate/uridylate-rich elements (AU-rich elements) to enhance stability and protein expression. Our investigation revealed that integrating AU-rich elements between the open reading frame (ORF) and the 3' untranslated region (3' UTR) significantly enhances RNA stability compared with other insertion sites. We identified cytoplasmic Human antigen R (HuR) as an essential RNA-binding protein responsible for promoting mRNA stability and translation, confirmed through HuR knockdown experiments and pull-down assays between AU-rich elements and HuR. Through rational design, we optimized the sequence of natural AU-rich elements and identified the essential "AUUUA" element, which, with certain repeats, can increase protein expression up to 5-fold. To demonstrate the universality of AU-rich element sequences in enhancing mRNA translation, we switched the coding proteins from luciferase to EGFP, mCherry, and ovalbumin (OVA), finding that both natural and engineered AU-rich element sequences amplify the expression of these proteins. In conclusion, leveraging the functionalities of RNA-binding proteins and the natural regulation of RNA stability in the untranslated region represents a novel strategy to enhance mRNA pharmacokinetics in the cytoplasm, expanding the potential applications of mRNA in therapeutic drugs.

Novel copy number variation of COLQ gene in a Moroccan patient with congenital myasthenic syndrome: a case report and review of the literature

Background

Congenital myasthenic syndromes (CMSs) are rare genetic diseases due to abnormalities of the neuromuscular junction leading to permanent or transient muscle fatigability and weakness. To date, 32 genes were found to be involved in CMSs with autosomal dominant and/or recessive inheritance patterns. CMS with acetylcholinesterase deficiency, in particular, was determined to be due to biallelic mutations of COLQ gene with early-onset clinical signs. Here, we report clinical features and novel molecular findings of COLQ-related CMS in a Moroccan patient with a review of the literature for this rare form.

Case presentation

In this study, we report the case of a 28-month-old Moroccan female patient with hypotonia, associated to axial muscle weakness, global motor delay, bilateral ptosis, unilateral partial visual field deficiency with normal ocular motility, and fatigable muscle weakness. Clinical exome sequencing revealed a novel homozygous deletion of exon 13 in COLQ gene, NM_005677.4(COLQ):c.(814+1_815-1)_(954+1_955-1) del p.(Gly272Aspfs*11). This finding was subsequently confirmed by quantitative real-time PCR (qPCR) in the proband and her parents. In silico analysis of protein-protein interaction network by STRING tool revealed that 12 proteins are highly associated to COLQ with an elevated confidence score. Treatment with Salbutamol resulted in clear benefits and recovery.

Conclusions

This clinical observation illustrates the important place of next-generation sequencing in the precise molecular diagnosis of heterogeneous forms of CMS, the appropriate management and targeted treatment, and genetic counseling of families, with a better characterization of the mutational profile of this rare disease in the Moroccan population.