GRN could refer to:
Granulin is a protein that in humans is encoded by the GRN gene.
Granulins are a family of secreted, glycosylated peptides that are cleaved from a single precursor protein with 7.5 repeats of a highly conserved 12-cysteine granulin/epithelin motif. The 88 kDa precursor protein, progranulin, is also called proepithelin and prostate cancer (PC) cell-derived growth factor. Cleavage of the signal peptide produces mature granulin which can be further cleaved into a variety of active, 6 kDa peptides. These smaller cleavage products are named granulin A, granulin B, granulin C, etc. Epithelins 1 and 2 are synonymous with granulins A and B, respectively.
Both the peptides and intact granulin protein regulate cell growth. However, different members of the granulin protein family may act as inhibitors, stimulators, or have dual actions on cell growth. Granulin family members are important in normal development, wound healing, and tumorigenesis.
The human liver fluke (Opisthorchis viverrini) contributes to the development of bile duct (liver) cancer by secreting a granulin-like growth hormone.
GRN-529 is a research drug that was developed by Wyeth as a negative allosteric modulator of the metabotropic glutamate receptor 5 (mGluR5).
A study conducted by Pfizer found that GRN-529 reduced repetitive behaviors without sedation and partially increased sociability in mouse models of autism.
Another study conducted by Pfizer found a therapeutically relevant effect in animal models of depression. It is theorized to work by reducing glutamate receptor hyperactivity.