The Transcriptional and Translational Control of Diazepam Binding Inhibitor Expression in Rat Male Germ-Line Cells

Abstract

The diazepam binding inhibitor [DBI, also known as acyl-CoA-binding protein, (ACBP), or endozepine] is a 10-kD protein that has been suggested to be involved in the regulation of several biological processes such as acyl-CoA metabolism, steroidogenesis, insulin secretion, and gamma-aminobutyric acid type A (GABA(A))/benzodiazepine receptor modulation. DBI has been cloned from vertebrates, insects, plants, and yeasts. In mammals, DBI is expressed in almost all the tissues studied. Nevertheless, DBI expression is restricted to specific cell types. Here we have studied DBI gene expression in the germ-line cells of rat testis. The DBI gene was intensively transcribed in postmeiotic round spermatids from stages VI to VIII of the seminiferous epithelial cycle. A prominent, spermatid-specific upstream transcription initiation site was identified in addition to the multiple common transcriptional initiation sites found in the somatic tissues. However, no DBI protein was detected in round spermatids, suggesting that the DBI transcripts were translationally arrested. The DBI protein was detected in the late spermatogenic stages starting from elongating spermatids from step 18 (stage VI) onward. The DBI protein was also detected in mature spermatozoa and in ejaculated human sperms. The majority of DBI was located at the middle piece of the spermatozoons tail enriched with mitochondria. On the basis of this observation and the well-established role of DBI in acyl-CoA metabolism, we propose that DBI expression in spermatozoa reflects the usage of fatty acids as a primary energy source by spermatozoa. The biological function of DBI in spermatozoa could thus be related to the motility function of sperm.

Molecular cloning and expression profiles of the acyl‐CoA‐binding protein gene from the cotton bollworm Helicoverpa armigera

“…Increasing evidence regarding the cell typespecific expression of ACBP in several mammalian tissues supports the notion that specific regulatory mechanisms exist for ACBP gene expression (Kolmer et al, 1997). We hypothesized that the differential expression of HaACBP at the RNA and protein levels was due to either a posttranscriptional regulatory mechanism for the HaACBP expression or a delay in protein translation.…”

Connecting cis-elements and trans-factors with mechanisms of developmental regulation of mRNA translation in meiotic and haploid mammalian spermatogenic cells

“…RT-PCR and northern blots concur that the Pgk2 mRNA is expressed from preleptotene spermatocytes to elongated spermatids (McCarrey et al 1992, Yoshioka et al 2007, while immunocytochemistry in four laboratories reveals that the PGK2 protein is first detected in step 9 (Vandeberg et al 1981) or step 12 spermatids (Kramer 1981, Bluthmann et al 1982, Danshina et al 2010. Similarly, in situ hybridization and immunohistochemistry demonstrate that the Dbil5 mRNA and protein are respectively first detected in step 6-8 and step 16 spermatids in rats (Kolmer et al 1997, Pusch et al 2000. The developmental expression of the Dbil5 and Pgk2 mRNAs and proteins is diagrammed in Fig.…”

Cloning and expression of the translocator protein (18kDa), voltage-dependent anion channel, and diazepam binding inhibitor in the gonad of largemouth bass (Micropterus salmoides) across the reproductive cycle

“…It is unknown to what degree genes involved in MCT are expressed in teleost germline cells. In mammals, Kolmer and colleagues [30] found a high abundance of dbi transcripts in developing spermatids, followed by non-detection of dbi during the later stages of spermatid differentiation. Vdac2 is expressed and translated in mammalian spermatocytes and spermatids, and the protein can be found in mature spermatozoa [37].…”