scholarly journals A role for calmodulin in the regulation of steroidogenesis

1981 ◽  
Vol 90 (2) ◽  
pp. 402-407 ◽  
Author(s):  
PF Hall ◽  
S Osawa ◽  
CL Thomasson
Keyword(s):  
Cyclic Amp ◽  
Adrenal Tumor ◽  
Side Chain ◽  
Dibutyryl Cyclic Amp ◽  
Steroid Production ◽  
Steroid Synthesis ◽  
Side Chain Cleavage ◽  
Cleavage Activity ◽  
Chain Cleavage

Two approaches were used to study the possible role of calmodulin in the regulation of steroid synthesis by mouse adrenal tumor cells: trifluoperazine was used as an inhibitor of calmodulin and liposomes were used to deliver calmodulin into the cells. Trifluoperazine inhibits three steroidogenic responses to both ACTH and dibutyryl cyclic AMP: (a) increase in steroid production, (b) increased transport of cholesterol to mitochondria, and (c) increased side-chain cleavage by mitochondria isolated from cells incubated with ACTH or dibutyryl cyclic AMP. When calmodulin is introduced into the cells via liposomes, steroid synthesis is slightly stimulated. When calmodulin extensively dialyzed against EGTA, this stimulation is abolished. Ca(2+) introduced via liposomes was also without effect. However, when both calmodulin and Ca(2+) are introduced via liposomes (either in separate liposomes or in the same liposomes), steroid synthesis is stimulated. This stimulation does not occur when either anticalmodulin antibodies or EGTA is also present in the liposomes or when trifluoperazine is present in the incubation medium. Calmodulin and Ca(2+) presented together in liposomes to the cells stimulate transport of cholesterol to mitochondria, and side-chain cleavage activity is greater in mitochondria isolated from cells previously fused with liposomes containing calmodulin and Ca(2+) than in mitochondria from cells fused with liposomes containing buffer only. These observations suggest that calmodulin may be involved in regulating the transport of cholesterol to mitochondria, a process which is stimulated by ACTH and dibutyryl cyclic AMP and which may account, at least in part, for the increase in steroid synthesis produced by these agents.

Critical role of the plasma membrane for expression of mammalian mitochondrial side chain cleavage activity in yeast

2003 ◽  
Vol 270 (7) ◽  
pp. 1502-1514 ◽  
Author(s):  
Catherine Duport ◽  
Barbara Schoepp ◽  
Elise Chatelain ◽  
Roberto Spagnoli ◽  
Bruno Dumas ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Critical Role ◽  
Side Chain ◽  
Side Chain Cleavage ◽  
Cleavage Activity ◽  
Chain Cleavage

scholarly journals Role of actin in the responses of adrenal cells to ACTH and cyclic AMP: inhibition by DNase I.

1984 ◽  
Vol 99 (4) ◽  
pp. 1335-1342 ◽  
Author(s):  
S Osawa ◽  
G Betz ◽  
P F Hall
Keyword(s):  
Cyclic Amp ◽  
Adrenal Tumor ◽  
Dnase I ◽  
Erythrocyte Ghosts ◽  
Dibutyryl Cyclic Amp ◽  
Inner Mitochondrial Membrane ◽  
Steroid Synthesis ◽  
Adrenal Cells ◽  
Amp Inhibition

Erythrocyte ghosts were loaded with pancreatic DNase I and fused with Y-1 adrenal tumor cells to test the possibility that this enzyme might inhibit the steroidogenic responses of the cells to ACTH and cyclic AMP. Fusion of erythrocyte ghosts loaded with DNase I, but not those containing albumin, ovalbumin, boiled DNase I, or DNase I with excess G-actin, inhibited the increase in production of 20 alpha-dihydroprogesterone produced by ACTH and dibutyryl cyclic AMP; inhibition was concentration-dependent with 50% inhibition by 3 X 10(7) molecules of DNase I per cell. It was found that inhibition by DNase I was exerted at the step in the steroidogenic pathway at which cholesterol is transported to mitochondria where steroidogenesis begins. This was shown by measuring transport of cholesterol into the inner mitochondrial membrane, by measuring the production of pregnenolone by isolated mitochondria and by demonstrating that DNase I was without effect on the conversion of pregnenolone to 20 alpha-dihydroprogesterone (an end-product of steroid synthesis). The actin content of Y-1 cells was measured by two methods based upon inhibition of DNase I and by SDS gels following centrifugation. The cells were found to contain 2-3 X 10(7) molecules of actin per cell of which two-thirds is present as G-actin. Since DNase I is known to bind to G-actin to give a one to one complex, these and other findings suggest that at least some of the G-actin in the cells may be necessary for the steroidogenic responses to ACTH and cyclic AMP.

scholarly journals Interaction of human CYP17 (P-45017α, 17α-hydroxylase-17,20-lyase) with cytochrome b5: importance of the orientation of the hydrophobic domain of cytochrome b5

1997 ◽  
Vol 321 (3) ◽  
pp. 857-864 ◽  
Author(s):  
Peter LEE-ROBICHAUD ◽  
Mustak A. KADERBHAI ◽  
Naheed KADERBHAI ◽  
J. Neville WRIGHT ◽  
Muhammad AKHTAR
Keyword(s):  
Signal Sequence ◽  
Cytochrome B5 ◽  
Amino Acid Sequences ◽  
Side Chain ◽  
Hydrophobic Domain ◽  
Side Chain Cleavage ◽  
The Core ◽  
Cleavage Activity ◽  
P450 Reductase ◽  
Chain Cleavage

Human CYP17 (P-45017α, 17α-hydroxylase-17,20-lyase)-catalysed side-chain cleavage of 17α-hydroxyprogestogens into androgens is greatly dependent on the presence of cytochrome b5. The native form of cytochrome b5 is composed of a globular core, residues 1Ő98, followed by a membrane insertable C-terminal tail, residues 99Ő133. In the present study the abilities of five different forms of cytochrome b5 to support the side-chain cleavage activity of CYP17 were compared. The five derivatives were: the native pig cytochrome b5 (native pig), its genetically engineered rat counterpart (coreŐtail), the soluble core form of the latter (core), the core with the secretory signal sequence of alkaline phosphatase appended to its N-terminal (signalŐcore) and the latter containing the C-terminal tail of the native rat protein (signalŐcoreŐtail). When examined by Edman degradation and MS, the engineered proteins were shown to have the expected N-terminal amino acid sequences and molecular masses. The native pig was found to be acetylated at the N-terminal. The native pig and coreŐtail enzymes were equally efficient at enhancing the side-chain cleavage activity of human CYP17 and the signalŐcoreŐtail was 55% as efficient. The core and signalŐcore constructs were completely inactive in the aforementioned reaction. All the five derivatives were reduced to varying degrees by NADPH:cytochrome P-450 (NADPH-P450) reductase and the relative efficiencies of this reduction were reminiscent of the behaviour of these derivatives in supporting the side-chain cleavage reaction. In the side-chain cleavage assay, however, NADPH-P450 reductase was used in large excess so that the reduction of cytochrome b5 derivatives was not rate-limiting. The results highlight that productive interaction between cytochrome b5 and CYP17 is governed not only by the presence of a membrane insertable hydrophobic region on the cytochrome b5 but also by its defined spatial orientation at the C-terminal.

CONGENITAL ADRENAL HYPERPLASIA DUE TO DEFICIENT CHOLESTEROL SIDE-CHAIN CLEAVAGE ACTIVITY (20, 22-DESMOLASE) IN A PATIENT TREATED FOR 18 YEARS

1985 ◽  
Vol 23 (5) ◽  
pp. 481-493 ◽  
Author(s):  
B. P. HAUFFA ◽  
W. L. MILLER ◽  
M. M. GRUMBACH ◽  
F. A. CONTE ◽  
SELNA L. KAPLAN
Keyword(s):  
Congenital Adrenal Hyperplasia ◽  
Side Chain ◽  
Adrenal Hyperplasia ◽  
Side Chain Cleavage ◽  
Cleavage Activity ◽  
Chain Cleavage

scholarly journals Role of Steroidogenic-Factor 1 in Basal and 3′,5′-Cyclic Adenosine Monophosphate-Mediated Regulation of Cytochrome P450 Side-Chain Cleavage Enzyme in the Mouse1

1997 ◽  
Vol 57 (4) ◽  
pp. 765-771 ◽  
Author(s):  
Yuen M. Chau ◽  
Peter A. Crawford ◽  
Karen G. Woodson ◽  
Jeffrey A. Polish ◽  
Lisa M. Olson ◽  
...  
Keyword(s):  
Cytochrome P450 ◽  
Cyclic Adenosine Monophosphate ◽  
Adenosine Monophosphate ◽  
Side Chain ◽  
Steroidogenic Factor 1 ◽  
Side Chain Cleavage ◽  
Chain Cleavage ◽  
Cleavage Enzyme
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