Basal adrenocorticotropin (ACTH) secretion is negatively modulated by protein phosphatase 5 in mouse pituitary corticotropin AtT20 cells.
siRNA oligonucleotides for protein phosphatase 5 (PP5) were designed and transfected into mouse corticotroph AtT20 cells to induce lower PP5 expression levels. PP5-siRNA transfections (at 3 days) produced a approximately 50% down-regulation in targeted protein levels. PP5- underexpressing cells released significantly more ir-ACTH (10-12-fold) relative to baseline levels and promoted POMC release into the media. Neither CRF- mediated ACTH release nor dexamethasone-induced ACTH repression were affected in PP5-siRNA transfected cells. In summary, our observations suggest that endogenous PP5 can exert a negative modulatory effect on basal ACTH release in neurosecretion-competent AtT20 cells through a mechanism as yet unknown but which does not directly involve regulated CRF or glucocorticoid receptor-dependent pathways. However, PP5 may cause mis-sorting of POMC and POMC-derived peptides at the constitutive-like secretory pathway level in an unregulated manner. Such a missorting could lead to impaired processing of POMC.[1]References
- Basal adrenocorticotropin (ACTH) secretion is negatively modulated by protein phosphatase 5 in mouse pituitary corticotropin AtT20 cells. Liu, F., Khawaja, X. Regul. Pept. (2005) [Pubmed]
Annotations and hyperlinks in this abstract are from individual authors of WikiGenes or automatically generated by the WikiGenes Data Mining Engine. The abstract is from MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.About WikiGenesOpen Access LicencePrivacy PolicyTerms of Useapsburg