INVESTIGADORES
BELGOROSKY Alicia
artículos
Título:
The cytochrome cP450 lacking exon 5 is associated with a phenotype of non-classic aromatase deficiency, and it is also present in normal human steroidogenic tissues.
Autor/es:
PEPE CM,; SARACO NI,; BAQUEDANO MS,; GUERCIO G,; VAIANI E,; MARINO R,; PANDEY AV,; FLÜCK CH E,; RIVAROLA MA,; BELGOROSKY, A
Revista:
Clinical Endocrinology
Editorial:
Blackwell Synergy
Referencias:
Lugar: Oxford; Año: 2007 vol. 67 p. 698 - 705
ISSN:
0300-0664
Resumen:
Summary
Objective
The previously described c655G>A mutation of the
human cytochrome P450 aromatase gene (P450aro,
CYP19
)
results in aberrant splicing due to disruption of a donor splice site.
To explain the phenotype of partial aromatase deficiency observed
in a female patient described with this mutation, molecular
consequences of the c655G>A mutation were investigated.
Design
To investigate whether the c655G>A mutation causes an
aberrant spliced mRNA lacking exon 5 (?Ex5), P450aro RNA was
analysed from the patient?s lymphocytes by reverse transcription
polymerase chain reaction (RT-PCR) and by splicing assays performed
in Y1 cells transfected with a P450aro ?Ex5 expression vector.
Aromatase activity of the c655G>A mutant was predicted by three
dimensional (3D) protein modelling studies and analysed in transiently
transfected Y1 cells. Exon 5 might be predicted as a poorly
defined exon suggesting a susceptibility to both splicing mutations
and physiological alternative splicing events. Therefore, expression of
the ?Ex5 mRNA was also assessed as a possibly naturally occurring
alternative splicing transcript in normal human steroidogenic tissues.
Patients
An aromatase deficient girl was born with ambiguous
genitalia. Elevated serum LH, FSH and androgens, as well as cystic
ovaries, were found during prepuberty. At the age of 8·4 years, spontaneous
breast development and a 194·6 pmol/l serum oestradiol
level was observed.
Results
The ?Ex5 mRNA was found in lymphocytes of the P450aro
deficient girl and her father, who was a carrier of the mutation. Mutant
minigene expression resulted in complete exon 5 skipping. As
expected from 3D protein modelling, ?Ex5 cDNA expression in
Y1 cells resulted in loss of P450aro activity. In addition, the ?Ex5
mRNA was present in placenta, prepubertal testis and adrenal tissues.
Conclusions
Alternative splicing of exon 5 of the
CYP19
gene
occurs in the wild type (WT) as well as in the c655G>A mutant.
We speculate that for the WT it might function as a regulatory
mechanism for aromatization, whereas for the mutant a relative
prevalence of the shorter over the full-length protein might explain
the phenotype of partial aromatase deficiency.
(Received 12 March 2007; returned for revision 13 April 2007; finally
revised 7 May 2007; accepted 7 May 2007)