Regulation of the Acute Production of Steroids in Steroidogenic Cells
The mechanism regulating the production of steroids in response to trophic hormone stimulation has been the subject of investigation for over three decades. When considering the effects of trophic hormones on the steroidogenic process it is necessary to f
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4.1 4.2
Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. Proposed Mechanisms Involved in the Acute Regulation of Steroidogenesis. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 4.2.1 Cellular Architecture. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 4.2.2 Sterol Carrier Protein 2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 4.2.3 Steroidogenesis Activator Peptide. . . . . . . . . . . . . . . . . . . . . . . . . .. 4.2.4 Peripheral Benzodiazepine Receptor and 8.2-kDa Protein. . . . . . .. 4.2.5 The 30-kDa Mitochondrial Proteins. . . . . . . . . . . . . . . . . . . . . . . .. 4.3 Role of Transcription. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 4.4 Role of Phosphorylation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 4.5 Correlations Between Steroidogenesis and the 30-kDa Proteins. .. 4.6 Molecular Characterization of the 30-kDa Proteins. . . . . . . . . . . .. 4.6.1 Purification.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 4.6.2 Amino Acid Sequence Determination. . . . . . . . . . . . . . . . . . . . . . .. 4.6.3 Cloning and Sequencing. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 4.7 Conclusions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. References .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..
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4.1 Introduction The mechanism regulating the production of steroids in response to trophic hormone stimulation has been the subject of investigation for over three decades. When considering the effects of trophic hormones
G. Verhoeven et al. (eds.), Molecular and Cellular Endocrinology of the Testis © Springer-Verlag Berlin Heidelberg 1994
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D.M. Steeee and B.J. Clark
on the steroidogenic process it is necessary to first distinguish between acute effects and chronic effects. Acute effects are those which result in the very rapid (within minutes) synthesis and secretion of steroids in response to hormone stimulation and involve the rapid translocation of intracellular cholesterol to the site of its cleavage, as will be discussed later. Chronic effects are those which occur on the order of hours to tens of hours and involve increased gene transcription and translation of the proteins involved in the biosynthesis of steroids. This chapter will focus on studies designed to elucidate the mechanisms involved in the acute regulation of steroid production in response to hormone stimulation. Overviews of the effects of chronic stimulation on steroidogenic enzymes have appeared in several excellent review articles (Simpson and Waterman 1983; Miller 1988; Hanukoglu 1992). Cholesterol transport within steroidogenic cells can be thought of as occurring in two separate processes. The first part of the process is the mobilization of cholesterol from cellul
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