LEMD2, also known as LEM domain-containing protein 2, is an inner nuclear membrane protein. It is involved in maintaining nuclear envelope integrity and has a role in processes related to chromatin organization and nuclear shape regulation. Its functions are associated with pathways like nuclear envelope rupture repair, and it is of great biological importance, especially in the context of heart and nervous system development and function [1,2,3]. Genetic models, such as KO or CKO mouse models, have been crucial in studying LEMD2's functions.

Knock-in mice with the Lemd2 p.L13R mutation, mimicking a human homozygous mutation, developed cardiomyopathy with endocardial fibrosis, left ventricular dilatation, systolic dysfunction, ventricular arrhythmias, and conduction disease. The mutation led to increased nuclear membrane invaginations, decreased nuclear circularity, DNA damage, and premature senescence in cardiomyocytes. The p.L13R mutation in the LEM-domain disrupted the interaction between mutant LEMD2 and BAF, impairing nuclear envelope rupture repair capacity. This also resulted in cytoplasmic leakage of the DNA repair factor KU80, increased DNA damage, and recruitment of cGAS to the nuclear membrane and micronuclei [1]. Mice with cardiac-specific deletion of Lemd2 died shortly after birth due to heart abnormalities, with cardiomyocytes showing nuclear envelope deformations, extensive DNA damage, and apoptosis linked to p53 activation [3].

In conclusion, LEMD2 is essential for genome stability and cardiac function. Studies using KO/CKO mouse models have revealed its crucial role in preventing DNA-damage-dependent cardiomyopathy. Understanding LEMD2's functions through these models provides insights into the pathogenesis of certain heart diseases and may offer potential therapeutic targets for treatment [1,3].