Ptn, short for pleiotrophin, belongs to the subfamily of heparin-binding growth factors. It has diverse functions such as mitogenicity, inflammation, angiogenesis, oncogenesis, and stem cell self-renewal [2]. Ptn binds to its receptor, Receptor Protein Tyrosine Phosphatase (RPTP) β/ζ, and inactivates its phosphatase activity, triggering a pathway that regulates peripheral and central immune responses [1].

Mice lacking Ptn exhibit impaired adult hippocampal neurogenesis (AHN) accompanied by poor learning and memory, indicating that Ptn promotes NSPC proliferation and differentiation by activating AKT signaling, and its decrease with aging may contribute to cognitive impairment [3]. In deer antler stem cell regulation during tissue regeneration, the high levels of Ptn and its receptor PTPRZ reflect the antler stem cell activation status, and Ptn-PTPRZ signaling may be involved in regulating antler stem cell behavior [4]. In epithelial ovarian cancer, gene silencing of PTPRZ1 (Ptn's receptor) in EOC cell lines shows its essentiality for cell viability, and members of the MAPK family are likely effectors of Ptn signaling [5].

In conclusion, Ptn plays crucial roles in multiple biological processes and diseases. Its functions in AHN-related cognitive function, tissue regeneration, and cancer pathogenesis have been revealed through gene-knockout-based studies. Understanding Ptn's functions can provide potential therapeutic targets for treating age-related cognitive decline, degenerative diseases, and certain cancers.