Pleckstrin homology domain and leucine-rich repeat protein phosphatase 1 (PHLPP1) (PHLPP1)

Pleckstrin homology domain and leucine-rich repeat protein phosphatase 1 (PHLPP1) is a member of the PP2C family of serine/threonine phosphatases that serves as a critical negative regulator of the PI3K/Akt signaling pathway (UniProt O60346). It specifically dephosphorylates the hydrophobic motif (Ser473) of Akt, as well as specific isoforms of protein kinase C (PKC) and Mst1, thereby promoting apoptosis and inhibiting cell proliferation (PMID: 15808815). Because of its role in terminating pro-survival signaling, PHLPP1 acts as a tumor suppressor, and its expression is frequently lost or reduced in various malignancies, such as prostate, colon, and breast cancers (PMID: 18281287). Conversely, PHLPP1 is upregulated in certain degenerative conditions like osteoarthritis, where it contributes to chondrocyte dysfunction and cartilage breakdown by inhibiting anabolic signaling (PMID: 21362555). Therapeutic strategies targeting PHLPP1 include the development of small-molecule inhibitors to treat osteoarthritis or metabolic disorders, as well as RNA-based approaches like siRNA or antisense oligonucleotides to modulate its expression at the mRNA level. However, systemic inhibition of PHLPP1 poses significant safety challenges due to its fundamental role in preventing oncogenic transformation through the suppression of Akt-driven growth.

Other names

PHLPPSCOPPLEKHB1PHLPP1 mRNASuprachiasmatic nucleus circadian oscillatory proteinPleckstrin homology domain-containing family B member 1-like

Phosphatase inhibition; RNA interference; Antisense knockdown