Mas1 is a receptor for angiotensin 1-7 (A1-7), which is derived from angiotensin II by the action of angiotensin converting enzyme 2. It is a key component of the counter-regulatory ACE2/Ang-(1-7)/Mas1 axis of the renin-angiotensin system, inducing vasodilation, attenuating Ang II-induced vasoconstriction, and playing important roles in regulating vascular tone [1]. It is also involved in many biological processes such as ovarian function regulation, pain alleviation, and may participate in tumor-related processes [2,5]. Genetic models like KO/CKO mouse models can be valuable for studying its functions.

In breast cancer, MAS1 expression was attenuated in invasive ductal carcinoma, especially scirrhous IDC. Its decrease was associated with tumor growth, lymph node metastasis, and grade. MAS1 activation with A1-7 treatment suppressed cell growth, anti-apoptotic survival, and invasion in triple-negative breast cancer cell lines, while MAS1 knockdown enhanced these processes. In a syngeneic mouse model, combination treatment related to the ACE2/Ang-(1-7)/Mas1 axis showed synergic effects on tumor growth inhibition [3]. In endometriosis, MAS1 mRNA levels were increased in endometriotic ovarian tissues and eutopic proliferative endometria of endometriosis patients, and high MAS1 expression in the endometrium might promote the initiation of endometriosis [4].

In conclusion, Mas1 is an important receptor in the ACE2/Ang-(1-7)/Mas1 axis with functions in the vascular system, ovarian function, pain regulation, and potential roles in cancer and endometriosis. Studies on Mas1 KO/CKO mouse models, if available, could further clarify its role in these disease areas, providing insights into disease mechanisms and potential therapeutic targets.

References:

1. Kuriakose, Jithin, Montezano, Augusto C, Touyz, Rhian M. . ACE2/Ang-(1-7)/Mas1 axis and the vascular system: vasoprotection to COVID-19-associated vascular disease. In Clinical science (London, England : 1979), 135, 387-407. doi:10.1042/CS20200480. https://pubmed.ncbi.nlm.nih.gov/33511992/

2. Domińska, Kamila. 2020. Involvement of ACE2/Ang-(1-7)/MAS1 Axis in the Regulation of Ovarian Function in Mammals. In International journal of molecular sciences, 21, . doi:10.3390/ijms21134572. https://pubmed.ncbi.nlm.nih.gov/32604999/

3. Luo, Yi, Tanabe, Eriko, Kitayoshi, Misaho, Ohmori, Hitoshi, Kuniyasu, Hiroki. 2015. Expression of MAS1 in breast cancer. In Cancer science, 106, 1240-8. doi:10.1111/cas.12719. https://pubmed.ncbi.nlm.nih.gov/26080617/

4. Nakajima, Takahiro, Chishima, Fumihisa, Nakao, Takehiro, Yamamoto, Tatsuo, Kawana, Kei. 2018. The Expression of MAS1, an Angiotensin (1-7) Receptor, in the Eutopic Proliferative Endometria of Endometriosis Patients. In Gynecologic and obstetric investigation, 83, 600-607. doi:10.1159/000490561. https://pubmed.ncbi.nlm.nih.gov/29982252/

5. Yamagata, Ryota, Nemoto, Wataru, Fujita, Maho, Nakagawasai, Osamu, Tan-No, Koichi. . Angiotensin (1-7) Attenuates the Nociceptive Behavior Induced by Substance P and NMDA via Spinal MAS1. In Biological & pharmaceutical bulletin, 44, 742-746. doi:10.1248/bpb.b20-01004. https://pubmed.ncbi.nlm.nih.gov/33952831/