B6-hLMNA Mice

Figure 1. Gene editing strategy of B6-hLMNA mice. The sequence from the ATG start codon to ~0.5 kb downstream of 3’UTR of mouse Lmna will be replaced with the sequence from the ATG start codon to ~0.5 kb downstream of 3’UTR of human LMNA.

● Research on Hutchinson-Gilford Progeria Syndrome (HGPS);

● Research on neuromuscular diseases;

● Research on cardiovascular disease.

1. Detection of human LMNA gene expression

Figure 2. Human LMNA gene expression in the skeletal muscle and colon of 6-week-old male wild-type mice (B6N) and B6-hLMNA mice. The expression of the human LMNA gene was detected by RT-qPCR. The results showed significant expression of the human LMNA gene in the skeletal muscle and colon of B6-hLMNA mice, while the human LMNA gene was almost not expressed in B6N mice.

 

2. Detection of mouse Lmna gene expression

Figure 3. Mouse Lmna gene expression in the skeletal muscle and colon of 6-week-old male wild-type mice (B6N) and B6-hLMNA mice. The expression of the mouse Lmna gene was detected by RT-qPCR. The results showed the mouse Lmna gene was expressed in both the skeletal muscle and colon of B6N mice, while the mouse Lmna gene was not expressed in B6-hLMNA mice.

1. Basic information about the LMNA gene

https://rddc.tsinghua-gd.org/gene/4000

 

2. LMNA clinical variants

https://rddc.tsinghua-gd.org/ai/pathogenicity/result?id=1b7e71ee-6548-498c-ab15-c8acf82bf868

3. Disease introduction

Hutchinson-Gilford Progeria Syndrome (HGPS) is a rare genetic disease. Patients exhibit organ degeneration and physiological function decline in early infancy due to gene mutations. The rate of aging in patients is 5-10 times faster than that of normal people. The disease has obvious hormonal characteristics, and affected children are often stunted, bald, have limited joint mobility, and suffer from osteoporosis. Other key abnormalities include scalp veins protruding, delayed tooth eruption, impaired sexual maturation, and low-pitched voice. Most affected children die from cardiovascular disease or stroke due to the rapid development of atherosclerosis ^[1].

4. LMNA gene and mutations

The LMNA gene encodes lamin A/C, a member of the nuclear lamina protein family. The highly conserved nuclear lamina protein family is a network layer structure attached to the inner nuclear membrane of the eukaryotic cell nucleus during evolution. This nuclear lamina protein plays an important role in maintaining cell structure, mitosis, chromosome aggregation, and other aspects. The LMNA gene mutations can cause neuromuscular diseases, heart disease, HGPS, and other diseases. The gene contains 12 exons, and the splicing site carried by exon 10 leads to the production of two major subtypes of lamin A and C. More than 500 mutations have been found in the LMNA gene, most of which are dominant mutations and are associated with a series of laminopathies.

LMNA gene mutations associated with progeria syndrome can convert normal lamin A protein structure into a shortened, toxic progerin protein. The accumulation of progerin protein increases with age and exacerbates the symptoms of progeria patients. Approximately 90% of HGPS cases are caused by a c.1827C>T (p.Gly609Gly) mutation in exon 11 of the LMNA gene. This mutation partially activates a cryptic splice site and produces a truncated lamin A protein called progerin. Since the truncated protein lacks 50 amino acids, including the cleavage site for the protease ZMPSTE24, the C-terminus of the abnormal protein cannot be cleaved, resulting in the formation of permanently farnesylated and carboxymethylated progerin protein ^[2].

5. Function of non-coding DNA sequences

A c.937-11 C > G mutation in intron 5 of the LMNA gene can cause LMNA splicing abnormalities ^[3]. Furthermore, miR-124-3p can negatively regulate the expression of Lamin A/C by binding to the 3’UTR region of the Lmna gene in vascular smooth muscle cells. This may be a new therapeutic target for hypertension ^[4].

6. LMNA-targeted gene therapy

Currently, the LMNA-targeted drug pipeline is still in its early stages, and preclinical studies of related drug pipelines are being conducted closely. Therapies targeting the LMNA gene in the field of gene therapy have emerged, including antisense oligonucleotide (ASO) drugs and CRISPR gene editing technology. ASO drugs mediate the reduction of lamin A/C is a potential strategy for treating lamin A-specific diseases. Studies have shown that ASO drugs reduce the level of pregnenolone in the aorta and improve the pathological condition of the aorta. This study used Lmna^G609G/G609G mice with severe aortic lesions as a research model [1]. Furthermore, studies have used CRISPR gene therapy to specifically interfere with the expression of lamin A/C and pregnenolone by targeting exon 11 of the LMNA gene, which can inhibit HGPS in mouse models. It also used Lmna^G609G/G609G mice as a disease model ^[2].

7. Summary

The LMNA gene is an important pathogenic gene for neuromuscular diseases, cardiovascular disease, Hutchinson-Gilford Progeria Syndrome (HGPS), and other diseases. The pathogenesis is complex, and Lmna^G609G/G609G mice are commonly used as preclinical models for HGPS. Conducting preclinical experiments of gene therapy drugs using humanized mice can accelerate the development of drug pipelines into clinical stages. LMNA whole-genome humanized mice from Cyagen can be used for preclinical research on HGPS, and customized services can also be provided for different point mutations.