Srrm3, serine/arginine repetitive matrix protein 3, is an important RNA binding protein involved in alternative splicing regulation. It plays a crucial role in the regulation of microexons, which are involved in various biological processes such as vesicle transport, exocytosis, and cilia biogenesis. Srrm3 is also associated with the regulation of REST (RE1-silencing transcription factor) alternative splicing, affecting the expression of REST-repressed genes [2,4,5,6].

In mouse models, mutations in Srrm3 lead to defects in islet cell identity and function, resulting in hyperinsulinaemic hypoglycaemia as pancreatic islet microexons regulated by Srrm3 are crucial for balanced insulin secretion [1]. In zebrafish, deletion of Srrm3 causes widespread down-regulation of microexon inclusion from early developmental stages, leading to severe photoreceptor defects and blindness, highlighting its importance in maintaining photoreceptor transcriptomic specialization and outer segment maintenance [3]. Mice with mutations in both Srrm3 and Srrm4 die neonatally with severe splicing defects, indicating overlapping and essential roles of these two splicing factors in regulating GABAergic neurotransmission by inactivating REST [5].

In conclusion, Srrm3 is essential for regulating microexon-related biological processes and alternative splicing of key genes like REST. Its study using gene knockout mouse models has revealed its significance in diseases such as diabetes, retinal diseases, and those related to abnormal neurotransmission, providing insights into the underlying molecular mechanisms and potential therapeutic targets.