NONO, also known as non-POU domain-containing octamer-binding protein/p54nrb, belongs to the Drosophila behaviour/human splicing (DBHS) family. It is a multifunctional nuclear protein that rarely functions alone. NONO engages in almost every step of gene regulation, including mRNA splicing, DNA unwinding, transcriptional regulation, nuclear retention of defective RNA, and DNA repair. It is involved in numerous biological processes such as cell proliferation, apoptosis, migration, DNA damage repair, and is crucial for maintaining normal cellular functions [1,4].

In mouse models, smooth muscle-specific NONO-knockout mice were more susceptible to vascular calcification, with increased calcification severity and calcium deposition. This shows that NONO is a negative regulator of vascular calcification, inhibiting osteogenic differentiation of vascular smooth muscle cells via negatively regulating bone morphogenetic protein 2 (BMP2) transcription [2]. Global deletion of NONO in mice impaired early B-cell development at the pro-to pre-B-cell transition stage and B-cell maturation in the spleen, indicating its critical role in B-cell development and B-cell receptor (BCR)-induced B-cell activation [3]. Deletion of Nono in the murine KP (KRas G12D, Trp53 -/-) cell-based lung cancer model impaired the response to DNA damage, with hyperactivation of DSB signalling and reduced induction of Gadd45b, suggesting Nono mediates DNA repair via Gadd45b [5].

In conclusion, NONO is a key regulator in multiple biological processes. Mouse knockout models have revealed its significance in diseases like vascular calcification, B-cell-related disorders, and DNA damage response in cancer. Understanding NONO's functions through these models provides insights into disease mechanisms and potential therapeutic targets.