Procr, also known as Protein C receptor, functions as a signaling receptor and is crucial for the maintenance and self-renewal of various stem cells [2]. It has been implicated in multiple biological processes and is associated with pathways like the interaction with heat shock protein 90 (HSP90AA1), Src, and IGF1R upon ligand (protein C) stimulation [2]. Procr-expressing cells have been identified as progenitors in several tissues, highlighting its overall biological importance in tissue homeostasis and repair [1,2,4,5]. Genetic models, especially KO/CKO mouse models, are valuable for studying Procr.

In KO/CKO mouse models, conditional knockout of Procr in mammary stem cells (MaSCs) demonstrated its essentiality for mammary gland development and homeostasis [2]. Ablation of Procr+ cells in the ovarian surface epithelium (OSE) impeded the repair process after ovulatory rupture, indicating Procr+ cells' critical role in OSE repair [4]. In the pancreas, Procr+ cells were shown to be endocrine progenitors capable of long-term expansion into islet-like organoids, and these organoids could reverse diabetes when transplanted into diabetic mice [1,3].

In conclusion, Procr is essential for the maintenance and self-renewal of stem cells in various tissues, playing a significant role in processes such as tissue repair, organ development, and islet-related functions. Studies using Procr KO/CKO mouse models have provided insights into its functions in mammary gland development, ovarian epithelium repair, and pancreatic islet-related diseases, contributing to a better understanding of these biological processes and potential therapeutic strategies.