P57

P57 may refer to:

Cyclin-dependent kinase inhibitor 1C

Cyclin-dependent kinase inhibitor 1C (p57, Kip2), also known as CDKN1C, is protein which in humans is encoded by the CDKN1C imprinted gene.

Function

Cyclin-dependent kinase inhibitor 1C is a tight-binding inhibitor of several G1 cyclin/Cdk complexes and a negative regulator of cell proliferation. Mutations of CDKN1C are implicated in sporadic cancers and Beckwith-Wiedemann syndrome suggesting that it is a tumor suppressor candidate.

CDKN1C is a tumor suppressor human gene on chromosome 11 (11p15) and belongs to the cip/kip gene family. It encodes a cell cycle inhibitor that binds to G1 cyclin-CDK complexes. Thus p57KIP2 causes arrest of the cell cycle in G1 phase.

Clinical significance

A mutation of this gene may lead to loss of control over the cell cycle leading to uncontrolled cellular proliferation. p57KIP2 has been associated with Beckwith-Wiedemann syndrome (BWS) which is characterized by increased risk of tumor formation in childhood. Loss-of-function mutations in this gene have also been shown associated to the IMAGe syndrome (Intrauterine growth restriction, Metaphyseal dysplasia, Adrenal hypoplasia congenita, and Genital anomalies).

P57 (glycoside)

P57 is an oxypregnane steroidal glycoside isolated from the African cactiform Hoodia gordonii. P57 is thought to be the main active constituent from this plant that may be responsible for the possible appetite suppressant activity of Hoodia extracts.

In a rat study at Brown Medical School, intracerebroventricular injections of the purified P57 demonstrated that the compound has a likely central nervous system (CNS) mechanism of action. The studies demonstrated that the compound increases the content of ATP by 50-150% in hypothalamic neurons. In addition, third ventricle administration of P57 reduced subsequent 24-hour food intake by 40-60%.

See also

References