Smpd3, sphingomyelin phosphodiesterase 3, is a lipid-metabolizing enzyme. It is crucial for sphingomyelin hydrolysis to produce ceramide, thus playing a role in sphingolipid metabolism pathways. It has significance in multiple biological processes such as embryonic development, bone formation, and is associated with various diseases [2,3,4]. Genetic models, like knockout (KO) and conditional knockout (CKO) mouse models, are valuable for studying its functions.

In KO mouse models, Smpd3 deficiency leads to various phenotypes. In Smpd3flox/flox ; Osx-Cre mice where Smpd3 was ablated in Osx-expressing chondrocytes and osteoblasts during early skeletogenesis, there were delayed extracellular matrix mineralization and severe skeletal deformities. Postnatal ablation in 3-month-old Smpd3flox/flox ; Osx-Cre mice resulted in a milder bone mineralization defect but marked increase of unmineralized osteoid in fractured tibiae [3]. In smpd3-/-mouse brain, absence of SMPD3 in the Golgi compartment of neurons led to inhibition of Golgi vesicular protein transport and progressive cognitive impairment [5]. In hepatocyte-specific Smpd3 gene disruption, it alleviated metabolic-dysfunction-associated steatohepatitis (MASH) [1].

In conclusion, Smpd3 is essential for normal endochondral bone development, ECM mineralization, chondrocyte apoptosis, and neuronal proteostasis. Mouse KO/CKO models have revealed its role in diseases such as skeletal disorders, neurodegeneration, and MASH, providing insights into potential therapeutic targets for these conditions.