Pin1, also known as peptidyl-prolyl cis-trans isomerase NIMA-interacting 1, is a unique cis-trans peptidyl prolyl isomerase. It binds to and catalyzes cis-trans conformational changes of specific Ser/Thr-Pro motifs after phosphorylation, regulating the structure and function of its protein substrates. This process is involved in numerous biological pathways and is of great biological importance, playing roles in cell signaling, protein ubiquitination and degradation, and various physiological and disease states [2].

Pin1 -/- mice show developmental bone defects and reduced mineralization. Pin1 targets RUNX2, SMAD1/5, and β-catenin in the FGF, BMP, and WNT pathways, respectively, playing multiple roles in the crosstalk between different anabolic bone signaling pathways, such as controlling osteoblastogenesis and osteoclastogenesis [3]. Dysfunction or loss-of-function of Pin1 is an important step in Alzheimer's disease (AD) pathogenesis, suggesting its significance in neurodegeneration [1]. In addition, Pin1 deficiency has been proposed to be related to autism, potentially explaining some of its unique morphological features [4].

In conclusion, Pin1 is crucial in regulating protein conformation and function, influencing multiple biological processes. Gene knockout mouse models, like Pin1 -/- mice, have revealed its roles in bone development, neurodegenerative diseases such as AD, and potentially in autism. These findings contribute to understanding the mechanisms of these diseases and may offer new therapeutic directions.