RT Journal Article SR Electronic T1 Unifying design principles of endocrine gland mass and its regulatory circuits JF bioRxiv FD Cold Spring Harbor Laboratory SP 2023.07.03.547486 DO 10.1101/2023.07.03.547486 A1 Raz, Moriya A1 Milo, Tomer A1 Kohanim, Yael Korem A1 Karin, Omer A1 Tendler, Avichai A1 Bar, Alon A1 Glass, David S. A1 Mayo, Avi A1 Alon, Uri YR 2023 UL http://biorxiv.org/content/early/2023/07/03/2023.07.03.547486.abstract AB Hormones are regulatory molecules that impact physiological functions. Much is known about individual hormones, but general rules that connect the regulatory logic of different hormone systems are limited. In this study, we analyzed a range of human hormone systems using a mathematical approach to integrate knowledge on endocrine cells, target tissues and regulation, to uncover unifying principles and regulatory circuits. We find that the number of cells in an endocrine gland is proportional to the number of cells in its target tissues, as one single endocrine cell serves approximately 2000 target cells. We identified five classes of regulatory circuits, each has specific regulatory functions such as homeostasis or allostasis. The most complex class includes an intermediate gland, the pituitary, which can otherwise be considered redundant and exposes to fragilities. We suggest a tradeoff: with the price of fragilities comes advantages -amplification, buffering of hypersecreting tumors, and faster response times. By elucidating these unifying principles and circuits, this study deepens our understanding of the control of endocrine processes and builds the foundation for systems endocrinology.