Human immunodeficiency virus type 1 enhancer-binding protein 3 (SHN3)

Human immunodeficiency virus type 1 enhancer-binding protein 3, commonly known as Schnurri-3 (SHN3), is a large zinc-finger adapter protein that serves as a potent negative regulator of bone formation. It primarily functions within osteoblasts to control the levels of Runx2, the master transcription factor for bone development, by facilitating its polyubiquitination and subsequent proteasomal degradation through the E3 ubiquitin ligase WWP1. Furthermore, SHN3 acts as a dampener of the ERK MAPK signaling pathway downstream of Wnt signaling, which further suppresses osteoblast differentiation and activity. Because the loss of SHN3 leads to a significant increase in bone mass (osteosclerosis) without disrupting normal skeletal patterning, it is considered a highly promising therapeutic target for metabolic bone diseases. Research is currently focused on developing bone-targeted gene therapies, such as AAV-delivered microRNAs, to silence SHN3 and promote bone anabolic activity in conditions like osteoporosis, osteogenesis imperfecta, and rheumatoid arthritis. Additionally, SHN3 has been identified as a promoter of tumor growth and invasion in certain cancers, suggesting that its inhibition may also have applications in oncology. While no small-molecule inhibitors are currently in clinical use, experimental approaches using RNA interference have demonstrated efficacy in increasing bone density and mechanical strength in animal models.

Other names

Schnurri-3HIVEP3ZAS3KBP1KRCZNF40CFLJ16752KIAA1555

Inhibition of Schnurri-3 prevents the WWP1-mediated polyubiquitination and degradation of Runx2 and enhances ERK MAPK signaling, leading to increased osteoblast differentiation and bone anabolic activity.