Nptn, encoding Neuroplastin, is a cell recognition glycoprotein of the immunoglobulin superfamily. It participates in synapse formation and function, calcium signaling, and is associated with pathways involved in neurological processes, learning, and memory [2]. It also has a role in pancreatic β -cell function, male fertility, and hearing [1,3,4]. Gene knockout mouse models have been valuable in studying its functions.

In pancreatic β -cells, β cell-specific Nptn knockout (KO) mice showed improved glucose tolerance due to increased insulin secretion and β cell mass, along with enhanced proliferation and mitochondrial numbers in β cells. Nptn deficiency also conferred resistance to streptozotocin-induced diabetic phenotypes, indicating its role in regulating insulin secretion, proliferation, and inflammatory responses in pancreatic β -cells [1].

In male mice, Nptn-deficient (Nptn-/-) males were infertile, lacking mounting behavior and having low testosterone blood levels. Testosterone rise from juvenile to adult levels was absent, suggesting Nptn is essential for male fertility, mating, and adult testosterone levels [3].

In hearing-related studies, adult Nptn-/-mice were deaf, with hair cell and spiral ganglion cell degeneration over time. Conditional ablation of Nptn in specific cell types further demonstrated its importance in maintaining normal hearing function and PMCA 2 expression in outer hair cells [4].

In conclusion, Nptn is essential for multiple biological functions, including those related to pancreatic β -cell function, male fertility, and hearing. The gene knockout mouse models have significantly contributed to understanding the role of Nptn in these processes, providing insights into potential therapeutic targets for diseases such as diabetes mellitus, male infertility, and hearing impairments.