Linked Life Data

2855024

Source:http://linkedlifedata.com/resource/pubmed/id/2855024

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
12
pubmed:dateCreated
1989-7-14
pubmed:abstractText
Using a cloned Leydig tumor cell line (designated MA-10), we have studied the activity of cholesterol side-chain (CSCC) enzyme, the rate-determining step in steroidogenesis, in mitochondria isolated from cells pretreated either with human chorionic gonadotropin (hCG) or dibutyryl cyclic adenosine monophosphate (dbcAMP). Results showed a slight but significant increase in CSCC activity with treatment by cAMP (25% increase) and hCG (60% increase), as compared to mitochondria isolated from nontreated control cells. However, this stimulation of CSCC activity appears to be of limited significance when compared to the approximately 1000-fold or greater increase observed in progesterone production in the presence of hCG or dbcAMP. On the other hand, unstimulated MA-10 cells or isolated mitochondria efficiently converted 25-hydroxycholesterol and 22R-hydroxycholesterol into progesterone, and this conversion was not affected by cycloheximide. The addition of cholesterol to intact cells or to isolated mitochondria did not affect progesterone production. Our observations clearly indicate that given the proper hydroxy substrates (22R-hydroxycholesterol or 25-hydroxycholesterol), MA-10 Leydig cells are able to convert them into progesterone without any stimulation by steroidogenic stimuli, i.e. cAMP or hCG. Since MA-10 Leydig cells can efficiently convert 22R-hydroxycholesterol--an intermediate in CSCC reaction--into progesterone, these results suggest that the key regulatory step in the mechanism of trophic hormone-stimulated steroid production is the first hydroxylation step of the 3 sequential monooxygenation reactions involved in the conversion of cholesterol to pregnenolone.
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Dec
pubmed:issn
0300-9084
pubmed:author
pubmed:issnType
Print
pubmed:volume
70
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
1799-806
pubmed:dateRevised
2007-11-14
pubmed:meshHeading
pubmed:year
1988
pubmed:articleTitle
Stimulation of cholesterol side-chain cleavage enzyme activity by cAMP and hCG in MA-10 Leydig tumor cells.
pubmed:affiliation
Department of Biochemistry, Texas Tech University Health Sciences Center, Lubbock 79430.
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, P.H.S.