Progranulin, also known as granulin-epithelin precursor (GEP), PC cell-derived growth factor (PCDGF), acrogranin, and proepithelin, is a secreted glycoprotein with a wide range of biological functions. In the context of neurodegenerative diseases, progranulin has emerged as a key factor. It is highly expressed in the brain and is implicated in the pathogenesis of frontotemporal lobar degeneration (FTLD), a type of dementia characterized by the accumulation of abnormal proteins in the brain's frontotemporal lobes. Mutations in the progranulin gene can lead to a decrease in its levels, which is associated with an increased risk of developing FTLD. Progranulin also plays a role in metabolic diseases. It has been identified as an adipokine that is involved in diet-induced obesity and insulin resistance, revealing its metabolic function. Moreover, progranulin has been linked to inflammation and immune responses. It can modulate inflammation by binding to tumor necrosis factor receptors (TNFRs) and potentially influencing TNF-dependent signaling.