Complex role of the mitochondrial targeting signal in the function of steroidogenic acute regulatory protein revealed by bacterial artificial chromosome transgenesis in vivo

Goro Sasaki, Tomohiro Ishii, Pancharatnam Jeyasuria, Youngah Jo, Assaf Bahat, Joseph Orly, Tomonobu Hasegawa, Keith L. Parker

Research output: Contribution to journalArticle

29 Citations (Scopus)

Abstract

The steroidogenic acute regulatory protein (StAR) stimulates the regulated production of steroid hormones in the adrenal cortex and gonads by facilitating the delivery of cholesterol to the inner mitochondrial membrane. To explore key aspects of StAR function within bona fide steroidogenic cells, we used a transgenic mouse model to explore the function of StAR proteins in vivo. We first validated this transgenic bacterial artificial chromosome reconstitution system by targeting enhanced green fluorescent protein to steroidogenic cells of the adrenal cortex and gonads. Thereafter, we targeted expression of either wild-type StAR (WT-StAR) or a mutated StAR protein lacking the mitochondrial targeting signal (N47-StAR). In the context of mice homozygous for a StAR knockout allele (StAR-/-), all StAR activity derived from the StAR transgenes, allowing us to examine the function of the proteins that they encode. The WT-StAR transgene consistently restored viability and steroidogenic function to StAR-/- mice. Although the N47-StAR protein was reportedly active in transfected COS cells and mitochondrial reconstitution experiments, the N47-StAR transgene rescued viability in only 40% of StAR -/- mice. Analysis of lipid deposits in the primary steroidogenic tissues revealed a hierarchy of StAR function provided by N47-StAR: florid lipid deposits were seen in the adrenal cortex and ovarian theca region, with milder deposits in the Leydig cells. Our results confirm the ability of StAR lacking its mitochondrial targeting signal to perform some essential functions in vivo but also demonstrate important functional defects that differ from in vitro studies obtained in nonsteroidogenic cells.

Original languageEnglish
Pages (from-to)951-964
Number of pages14
JournalMolecular Endocrinology
Volume22
Issue number4
DOIs
Publication statusPublished - 2008 Apr

Fingerprint

Bacterial Artificial Chromosomes
Gene Transfer Techniques
Transgenes
steroidogenic acute regulatory protein
Adrenal Cortex
Gonads
Lipids
Proteins
Leydig Cells
COS Cells
Mitochondrial Proteins

ASJC Scopus subject areas

  • Molecular Biology
  • Endocrinology, Diabetes and Metabolism

Cite this

Complex role of the mitochondrial targeting signal in the function of steroidogenic acute regulatory protein revealed by bacterial artificial chromosome transgenesis in vivo. / Sasaki, Goro; Ishii, Tomohiro; Jeyasuria, Pancharatnam; Jo, Youngah; Bahat, Assaf; Orly, Joseph; Hasegawa, Tomonobu; Parker, Keith L.

In: Molecular Endocrinology, Vol. 22, No. 4, 04.2008, p. 951-964.

Research output: Contribution to journalArticle

@article{d552ff1eef1a46bab2e56b4028d9758c,
title = "Complex role of the mitochondrial targeting signal in the function of steroidogenic acute regulatory protein revealed by bacterial artificial chromosome transgenesis in vivo",
abstract = "The steroidogenic acute regulatory protein (StAR) stimulates the regulated production of steroid hormones in the adrenal cortex and gonads by facilitating the delivery of cholesterol to the inner mitochondrial membrane. To explore key aspects of StAR function within bona fide steroidogenic cells, we used a transgenic mouse model to explore the function of StAR proteins in vivo. We first validated this transgenic bacterial artificial chromosome reconstitution system by targeting enhanced green fluorescent protein to steroidogenic cells of the adrenal cortex and gonads. Thereafter, we targeted expression of either wild-type StAR (WT-StAR) or a mutated StAR protein lacking the mitochondrial targeting signal (N47-StAR). In the context of mice homozygous for a StAR knockout allele (StAR-/-), all StAR activity derived from the StAR transgenes, allowing us to examine the function of the proteins that they encode. The WT-StAR transgene consistently restored viability and steroidogenic function to StAR-/- mice. Although the N47-StAR protein was reportedly active in transfected COS cells and mitochondrial reconstitution experiments, the N47-StAR transgene rescued viability in only 40{\%} of StAR -/- mice. Analysis of lipid deposits in the primary steroidogenic tissues revealed a hierarchy of StAR function provided by N47-StAR: florid lipid deposits were seen in the adrenal cortex and ovarian theca region, with milder deposits in the Leydig cells. Our results confirm the ability of StAR lacking its mitochondrial targeting signal to perform some essential functions in vivo but also demonstrate important functional defects that differ from in vitro studies obtained in nonsteroidogenic cells.",
author = "Goro Sasaki and Tomohiro Ishii and Pancharatnam Jeyasuria and Youngah Jo and Assaf Bahat and Joseph Orly and Tomonobu Hasegawa and Parker, {Keith L.}",
year = "2008",
month = "4",
doi = "10.1210/me.2007-0493",
language = "English",
volume = "22",
pages = "951--964",
journal = "Molecular Endocrinology",
issn = "0888-8809",
publisher = "The Endocrine Society",
number = "4",

}

TY - JOUR

T1 - Complex role of the mitochondrial targeting signal in the function of steroidogenic acute regulatory protein revealed by bacterial artificial chromosome transgenesis in vivo

AU - Sasaki, Goro

AU - Ishii, Tomohiro

AU - Jeyasuria, Pancharatnam

AU - Jo, Youngah

AU - Bahat, Assaf

AU - Orly, Joseph

AU - Hasegawa, Tomonobu

AU - Parker, Keith L.

PY - 2008/4

Y1 - 2008/4

N2 - The steroidogenic acute regulatory protein (StAR) stimulates the regulated production of steroid hormones in the adrenal cortex and gonads by facilitating the delivery of cholesterol to the inner mitochondrial membrane. To explore key aspects of StAR function within bona fide steroidogenic cells, we used a transgenic mouse model to explore the function of StAR proteins in vivo. We first validated this transgenic bacterial artificial chromosome reconstitution system by targeting enhanced green fluorescent protein to steroidogenic cells of the adrenal cortex and gonads. Thereafter, we targeted expression of either wild-type StAR (WT-StAR) or a mutated StAR protein lacking the mitochondrial targeting signal (N47-StAR). In the context of mice homozygous for a StAR knockout allele (StAR-/-), all StAR activity derived from the StAR transgenes, allowing us to examine the function of the proteins that they encode. The WT-StAR transgene consistently restored viability and steroidogenic function to StAR-/- mice. Although the N47-StAR protein was reportedly active in transfected COS cells and mitochondrial reconstitution experiments, the N47-StAR transgene rescued viability in only 40% of StAR -/- mice. Analysis of lipid deposits in the primary steroidogenic tissues revealed a hierarchy of StAR function provided by N47-StAR: florid lipid deposits were seen in the adrenal cortex and ovarian theca region, with milder deposits in the Leydig cells. Our results confirm the ability of StAR lacking its mitochondrial targeting signal to perform some essential functions in vivo but also demonstrate important functional defects that differ from in vitro studies obtained in nonsteroidogenic cells.

AB - The steroidogenic acute regulatory protein (StAR) stimulates the regulated production of steroid hormones in the adrenal cortex and gonads by facilitating the delivery of cholesterol to the inner mitochondrial membrane. To explore key aspects of StAR function within bona fide steroidogenic cells, we used a transgenic mouse model to explore the function of StAR proteins in vivo. We first validated this transgenic bacterial artificial chromosome reconstitution system by targeting enhanced green fluorescent protein to steroidogenic cells of the adrenal cortex and gonads. Thereafter, we targeted expression of either wild-type StAR (WT-StAR) or a mutated StAR protein lacking the mitochondrial targeting signal (N47-StAR). In the context of mice homozygous for a StAR knockout allele (StAR-/-), all StAR activity derived from the StAR transgenes, allowing us to examine the function of the proteins that they encode. The WT-StAR transgene consistently restored viability and steroidogenic function to StAR-/- mice. Although the N47-StAR protein was reportedly active in transfected COS cells and mitochondrial reconstitution experiments, the N47-StAR transgene rescued viability in only 40% of StAR -/- mice. Analysis of lipid deposits in the primary steroidogenic tissues revealed a hierarchy of StAR function provided by N47-StAR: florid lipid deposits were seen in the adrenal cortex and ovarian theca region, with milder deposits in the Leydig cells. Our results confirm the ability of StAR lacking its mitochondrial targeting signal to perform some essential functions in vivo but also demonstrate important functional defects that differ from in vitro studies obtained in nonsteroidogenic cells.

UR - http://www.scopus.com/inward/record.url?scp=41649110527&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=41649110527&partnerID=8YFLogxK

U2 - 10.1210/me.2007-0493

DO - 10.1210/me.2007-0493

M3 - Article

VL - 22

SP - 951

EP - 964

JO - Molecular Endocrinology

JF - Molecular Endocrinology

SN - 0888-8809

IS - 4

ER -