Absence of RNA Synthesis in Shed Human Spermatozoa

Markewitz, Moshe; Graff, Samuel; Veenema, Ralph J.

doi:10.1038/214402b0

Cited by 8 publications

(5 citation statements)

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“…The question, therefore, of whether sperm has a translational capacity that cannot be ascribed to another contaminating cell type (including contaminating bacteria) remains open. De novo, chloramphenicol-(CP-) sensitive, mitochondrially directed protein synthesis in capacitating human sperm was recently demonstrated using the uptake of 35 S-methionine-lysine and BODIPY lysine tRNA [47] This report did not cite a study appearing three years earlier, concluding that protein synthesis in sperm was due to CP-sensitive bacterial contamination (repeating an assertion made almost 40 years previously; [53,54]). The only other report of de novo protein synthesis in sperm used a 2D PAGE based proteomic approach to identify 44 differentially expressed proteins in capacitated versus noncapacitated sperm including sperm capacitated in the presence of chloramphenicol [47].…”

Section: Historical Contextmentioning

confidence: 67%

“…In this regard, although a relationship between extra-mitochondrial mitochondrial ribosomes and germ cell formation has been reported in insects and fish [52], how such a mechanism can support the translation of cytoplasmic RNAs (including nuclear-encoded RNAs for mitochondrial proteins) demands explanation. In a cautionary context, other reports have suggested that the reported translational activity in ejaculate sperm (even mitochondrially driven) could also be an artifact of bacterial contamination [53,54]. The more recent of these reports, however, while implicating bacteria fell short of actually demonstrating their presence in semen samples concerned.…”

Section: Introductionmentioning

confidence: 67%

“…Much of the earliest research in this area focused on bovine spermatozoa that were shown either capable [61,62] or incapable [53,63,64] of making RNA or protein.…”

Section: Historical Contextmentioning

confidence: 99%

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Sperm RNA as a Mediator of Genomic Plasticity

Miller

2014

Advances in Biology

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Sperm RNA has been linked recently to trans-generational, non-Mendelian patterns of inheritance. Originally dismissed as "residual" to spermatogenesis, some sperm RNA may have postfertilization functions including the transmission of acquired characteristics. Sperm RNA may help explain how trans-generational effects are transmitted and it may also have implications for assisted reproductive technologies (ART) where sperm are subjected to considerable, ex vivo manual handling. The presence of sperm RNA was originally a controversial topic because nuclear gene expression is switched off in the mature mammalian spermatozoon. With the recent application of next generation sequencing (NGS), an unexpectedly rich and complex repertoire of RNAs has been revealed in the sperm of several species that makes its residual presence counterintuitive. What follows is a personal survey of the science behind our understanding of sperm RNA and its functional significance based on experimental observations from my laboratory as well as many others who have contributed to the field over the years and are continuing to contribute today. The narrative begins with a historical perspective and ends with some educated speculation on where research into sperm RNA is likely to lead us in the next 10 years or so.

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Section: Historical Contextmentioning

confidence: 67%

Section: Introductionmentioning

confidence: 67%

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Sperm RNA as a Mediator of Genomic Plasticity

Miller

2014

Advances in Biology

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“…A clear example suggesting a correlation between transcriptional activity and TFIIH levels was found when inspecting sections of testis, in particular the seminiferous tubules in which male germ cell development proceeds in a peripheral-to-central fashion. Indeed, during this process, chromatin in male germ cells is progressively condensed, concomitantly genes are silenced by promoter methylation and gradually basal transcription is reduced to undetectable levels [3, 14, 25]. Immunohistochemistry of the seminiferous tubules of an Xpb y/y mouse showed that TFIIH concentration follows the peripheral-to-central reduction of transcriptional activity (Fig.…”

Section: Resultsmentioning

confidence: 99%

Cell-type specific concentration regulation of the basal transcription factor TFIIH in XPBy/y mice model

et al. 2019

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Background The basal transcription/repair factor TFIIH is a ten sub-unit complex essential for RNA polymerase II (RNAP2) transcription initiation and DNA repair. In both these processes TFIIH acts as a DNA helix opener, required for promoter escape of RNAP2 in transcription initiation, and to set the stage for strand incision within the nucleotide excision repair (NER) pathway. Methods We used a knock-in mouse model that we generated and that endogenously expresses a fluorescent version of XPB (XPB-YFP). Using different microscopy, cellular biology and biochemistry approaches we quantified the steady state levels of this protein in different cells, and cells imbedded in tissues. Results Here we demonstrate, via confocal imaging of ex vivo tissues and cells derived from this mouse model, that TFIIH steady state levels are tightly regulated at the single cell level, thus keeping nuclear TFIIH concentrations remarkably constant in a cell type dependent manner. Moreover, we show that individual cellular TFIIH levels are proportional to the speed of mRNA production, hence to a cell’s transcriptional activity, which we can correlate to proliferation status. Importantly, cancer tissue presents a higher TFIIH than normal healthy tissues. Conclusion This study shows that TFIIH cellular concentration can be used as a bona-fide quantitative marker of transcriptional activity and cellular proliferation.

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“…Similar reports of the time were generally dismissed as artifacts of bacterial, erythrocyte or epithelial cell contamination. The suggestion that spermatozoal RNA synthesis was probably restricted to the mitochondria was based on an inability to detect such synthesis in the isolated heads of human spermatozoa (Markewitz et al, 1967). Sole incorporation into mitochondrial 23S, 16S and 4S RNAs was finally confirmed using inorganic [ 32 P]-phosphate (Premkumar and Bhargava, 1972) and [ 3 H] uridine (MacLaughlin and Terner, 1973) as tracers although the latter were unable to distinguish between 23S or 28S rRNA species.…”

Section: Ejaculate Spermatozoa As (Non-invasive) Biopsies Of the Haplmentioning

confidence: 99%

RNA in the ejaculate spermatozoon: a window into molecular events in spermatogenesis and a record of the unusual requirements of haploid gene expression and post-meiotic equilibration

Miller¹

1997

Molecular Human Reproduction

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Several reports demonstrating the presence of messenger RNAs for sperm-specific nucleoproteins, the protamines PRM-1, PRM-2, and the transition protein TP-1 as well as beta-actin, c-MYC, HLA1, and beta 1 integrin have challenged the accepted view of the transcriptional dormance of terminally differentiated spermatozoa. Whatever nuclear activity the ejaculate spermatozoon may possess, these data suggest that spermatozoa are a repository of information regarding meiotic and post-meiotic gene expression in the human and are likely to contain transcripts for many homologues of genes identified from animal models, which play an essential role in spermiogenesis. The use of ejaculate spermatozoa as a wholly non-invasive biopsy of the spermatid should now be evaluated. At the same time, spermatozoal RNAs require further analysis and characterization. One explanation for their persistence in ejaculate spermatozoa is that they serve to equilibrate imbalances in spermatozoal phenotypes brought about by melotic recombination and segregation. Transcript exchange is likely considering the presence of inter-cellular cytoplasmic bridges between haploid spermatids, which also offers a route for the translocation and expansion of non-mendelian trials linked to retrotransposon activity.

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Absence of RNA Synthesis in Shed Human Spermatozoa

Cited by 8 publications

References 5 publications

Sperm RNA as a Mediator of Genomic Plasticity

Sperm RNA as a Mediator of Genomic Plasticity

Cell-type specific concentration regulation of the basal transcription factor TFIIH in XPBy/y mice model

RNA in the ejaculate spermatozoon: a window into molecular events in spermatogenesis and a record of the unusual requirements of haploid gene expression and post-meiotic equilibration

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