|
|
|
|
|
|
|
||
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
J. Cell Biol.,
Volume 144, Number 3, February 8, 1999 459-471
* Departments of Neuroscience and Physiology and Peptidylglycine Departments of Pathology and Anesthesiology, The Johns Hopkins
University School of Medicine, Baltimore, Maryland 21205
-amidating monooxygenase
(PAM) is an essential enzyme that catalyzes the
COOH-terminal amidation of many neuroendocrine
peptides. The bifunctional PAM protein contains an
NH2-terminal monooxygenase (PHM) domain followed by a lyase (PAL) domain and a transmembrane
domain. The cytosolic tail of PAM interacts with proteins that can affect cytoskeletal organization. A reverse tetracycline-regulated inducible expression system was used to construct an AtT-20 corticotrope cell
line capable of inducible PAM-1 expression. Upon induction, cells displayed a time- and dose-dependent increase in enzyme activity, PAM mRNA, and protein.
Induction of increased PAM-1 expression produced graded changes in PAM-1 metabolism. Increased expression of PAM-1 also caused decreased immunofluorescent staining for ACTH, a product of proopiomelanocortin (POMC), and prohormone convertase 1 (PC1) in granules at the tips of processes. Expression of
PAM-1 resulted in decreased ACTH and PHM secretion in response to secretagogue stimulation, and decreased cleavage of PC1, POMC, and PAM. Increased expression of a soluble form of PAM did not alter
POMC and PC1 localization and metabolism. Using the
inducible cell line model, we show that expression of integral membrane PAM alters the organization of the
actin cytoskeleton. Altered cytoskeletal organization
may then influence the trafficking and cleavage of lumenal proteins and eliminate the ability of AtT-20 cells
to secrete ACTH in response to a secretagogue.
CiteULike 
Complore 
Connotea 
Del.icio.us 
Digg 
Reddit 
Technorati What's this?
This article has been cited by other articles:
|
|
