Progesterone-induced-blocking factor 1 (PIBF1)

Progesterone-induced-blocking factor 1 (PIBF1), also known as progesterone immunomodulatory binding factor 1, is a multifunctional protein induced by the steroid hormone progesterone[1][5]. PIBF1 plays a crucial role in immune modulation to maintain pregnancy by skewing the immune response toward a Th2 cytokine profile, suppressing natural killer cell cytotoxicity, and interfering with arachidonic acid metabolism[1][6]. It is also involved in ciliogenesis and centrosomal organization, with additional roles in proliferation and migration of cancer cells, especially glioma[1]. Mutations in PIBF1 are linked to ciliopathies, including Joubert syndrome 33, and low serum PIBF1 is associated with increased risk of preterm labor[1][6]. While it has a clear role as a molecular target in reproductive immunology and cancer biology, there are currently no approved drugs specifically acting on PIBF1. PIBF1 acts through signaling mechanisms involving cytokine modulation via the JAK/STAT pathway, but it does not fit classic definitions as a receptor or enzyme[1][6].

Other names

Progesterone immunomodulatory binding factor 1PIBF1PIBFCEP90C13orf24Chromosome 13 open reading frame 24Centrosomal protein of 90 kDaJBTS33

Immunomodulatory action via cytokine regulation (Th2 immune bias) and suppression of NK cell cytotoxicity through JAK/STAT pathway activation (notably STAT6 activation and STAT4 inhibition) Acts as a mediator of progesterone’s immuno-protective effects during pregnancy Works through interaction with unidentified receptors, possibly implicating IL4R and GPI-anchored proteins[1][6]