The invariant chain CD74 protein is a cell surface binding partner of TIMP-1 in breast cancer cells.

Tissue inhibitor of metalloproteinases-1 (TIMP-1) regulates the proteolytic activity of matrix metalloproteinases (MMPs), playing an important role in the homeostasis of the extracellular matrix. Beyond its well-known role in tissue maintenance, TIMP-1 has been associated with multiple MMP-independent cytokine-like functions. The protein structure of TIMP-1, with two distinct domains, one interacting with MMPs and another able to bind multiple partners, provides a rationale for this multifunctionality. The identification of CD63 as a cell surface receptor for TIMP-1, able to mediate intracellular signaling through the Erk/MAPK axis, provided a molecular basis for the role of TIMP-1 in cellular signaling. However, several lines of evidence suggest that TIMP-1 may be able to associate with many interaction partners, thus attaining multiple functions. To enable the identification of previously unknown interaction partners that may underpin the core cellular functions of TIMP-1, known as well as unknown, we performed a yeast two-hybrid screening using a mammary gland complementary DNA (cDNA) library. We report here the identification of multiple interactors, including MHC class II-associated invariant chain γ (CD74). We verified that CD74 interacts with TIMP-1 in breast cancer cells and that this interaction contributes to cellular internalization of TIMP-1 and mediates intracellular signaling through the Akt signaling axis in breast cancer cells. These data provide new insights into the complex nature of the functions of TIMP-1 and their potential mechanistic basis.

Lipidated PrRP31 metabolites are long acting dual GPR10 and NPFF2 receptor agonists with potent body weight lowering effect.

Prolactin-releasing peptide (PrRP) is an endogenous neuropeptide involved in appetite regulation and energy homeostasis. PrRP binds with high affinity to G-protein coupled receptor 10 (GPR10) and with lesser activity towards the neuropeptide FF receptor type 2 (NPFF2R). The present study aimed to develop long-acting PrRP31 analogues with potent anti-obesity efficacy. A comprehensive series of C18 lipidated PrRP31 analogues was characterized in vitro and analogues with various GPR10 and NPFF2R activity profiles were profiled for bioavailability and metabolic effects following subcutaneous administration in diet-induced obese (DIO) mice. PrRP31 analogues acylated with a C18 lipid chain carrying a terminal acid (C18 diacid) were potent GPR10-selective agonists and weight-neutral in DIO mice. In contrast, acylation with aliphatic C18 lipid chain (C18) resulted in dual GPR10-NPFF2R co-agonists that suppressed food intake and promoted a robust weight loss in DIO mice, which was sustained for at least one week after last dosing. Rapid in vivo degradation of C18 PrRP31 analogues gave rise to circulating lipidated PrRP metabolites maintaining dual GPR10-NPFF2R agonist profile and long-acting anti-obesity efficacy in DIO mice. Combined GPR10 and NPFF2R activation may therefore be a critical mechanism for obtaining robust anti-obesity efficacy of PrRP31 analogues.