Inhibitor induced alterations of chromatoid bodies in male germ line cells of Xenopus laevis

Kalt, Marvin R.; Pinney, H. E.; Graves, Kathy H.

doi:10.1007/bf00220368

Cited by 7 publications

(3 citation statements)

References 22 publications

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“…The CB contains ribosomal proteins and ribosomal RNAs, based on high-throughput analyses ( 15 ). Polysome-like structures have been observed in CB isolated from rat spermatids ( 75 ), and inhibition of protein synthesis dramatically increases the size of the CB in Xenopus laevis ( 76 ). Finally, the CB has a close physical association with the endoplasmic reticulum, where secreted and cell-surface proteins are translated ( 53 , 77 ).…”

Section: Discussionmentioning

confidence: 99%

SMG6 localizes to the chromatoid body and shapes the male germ cell transcriptome to drive spermatogenesis

Lehtiniemi

Bourgery

et al. 2022

Nucleic Acids Research

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Nonsense-mediated RNA decay (NMD) is a highly conserved and selective RNA turnover pathway that depends on the endonuclease SMG6. Here, we show that SMG6 is essential for male germ cell differentiation in mice. Germ-cell conditional knockout (cKO) of Smg6 induces extensive transcriptome misregulation, including a failure to eliminate meiotically expressed transcripts in early haploid cells, and accumulation of NMD target mRNAs with long 3′ untranslated regions (UTRs). Loss of SMG6 in the male germline results in complete arrest of spermatogenesis at the early haploid cell stage. We find that SMG6 is strikingly enriched in the chromatoid body (CB), a specialized cytoplasmic granule in male germ cells also harboring PIWI-interacting RNAs (piRNAs) and the piRNA-binding protein PIWIL1. This raises the possibility that SMG6 and the piRNA pathway function together, which is supported by several findings, including that Piwil1-KO mice phenocopy Smg6-cKO mice and that SMG6 and PIWIL1 co-regulate many genes in round spermatids. Together, our results demonstrate that SMG6 is an essential regulator of the male germline transcriptome, and highlight the CB as a molecular platform coordinating RNA regulatory pathways to control sperm production and fertility.

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Section: Discussionmentioning

confidence: 99%

SMG6 localizes to the chromatoid body and shapes the male germ cell transcriptome to drive spermatogenesis

Lehtiniemi

Bourgery

et al. 2022

Nucleic Acids Research

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“…The CB of Xenopus laevis is sensitive to the action of inhibitors of protein synthesis chloramphenicol or puromycin. These drugs administered in vivo or in vitro cause up to a 30-fold increase in the volume of the CB in all stages where it is normally present (Kalt et al, 1975). Comparable with the effect of nocodazole, another microtubule inhibitor vincristine caused a disintegration of the CB into small hollow spheres (Mali et al, 1988;Fig.…”

Section: Injury Of the Cbmentioning

confidence: 99%

Section: Injury Of the Cbmentioning

confidence: 99%

The chromatoid body in spermatogenesis

2005

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All germ cells throughout the animal kingdom contain cytoplasmic cloud-like accumulations of material called nuage. Polar bodies in Drosophila oocytes are probably the best known forms of nuage. In spermatogenic cells, the nuage is called chromatoid body (CB). In early spermatids of the rat, it has a diameter of 1-1.5 microm and a finely filamentous lobular structure. Typically, it is associated with a multitude of vesicles. It is first clearly seen in mid- and late pachytene spermatocytes as an intermitochondrial dense material. During early spermiogenesis it is seen near the Golgi complex and frequently connected by material continuities through nuclear pore complexes with intranuclear particles. In living cells, the CB moves around the Golgi complex and has frequent contacts with it. The CB also moves perpendicularly to the nuclear envelope, and even through cytoplasmic bridges to the neighbour spermatids. One of the major components of the CB is a DEAD-box RNA helicase VASA that belongs to a class of proteins thought to act as RNA chaperones. It is a general marker of all germ cells and best characterized in Drosophila. The mouse VASA homologue was recently used as a marker of sperm formation from embryonic stem cells. It becomes generally accepted that the CB with its associated structures constitute a mechanism of post-transcriptional processing and storage of several mRNA species that are shared between neighbour cells and used for translation when the genome of the spermatids becomes inactive.

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In vitro synthesis of RNA by Xenopus spermatogenic cells. I. Evidence for polyadenylated and non‐polyadenylated RNA synthesis in different cell populations

Kalt

1979

J. Exp. Zool.

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Premeiotic and postmeiotic (haploid) gene expression during spermatogenesis in the anuran, Xenopus laevis, was studied by analyzing the accumulation of radioactively labelled cytoplasmic polyadenylated [poly (A +)] and non-polyadenylated [poly (A -)] RNAs. Dissociated spermatogenic cells were labelled and maintained in an in vitro system capable of supporting cell differentiation. Labelled cells were separated by density gradient centrifugation into subpopulations enriched for individual spermatogenic stages. RNA was extracted and purified from each cell fraction, and separated into poly (A +) and poly (A -) species. Comparison of poly (A +) to non-poly (A) radioactivity in cells labelled with tritiated uridine or adenosine demonstrated that (1) all cell fractions produced significant quantities of polyadenylated RNA relative to total RNA synthesis; and (2) that a cell fraction enriched for pachytene spermatocyte RNA contained up to 15% of total cytoplasmic and 35% of total polysomal RNA labelled as poly (A +) containing species. RNA was also characterized by sucrose density gradient centrifugation and polyacrylamide gel electrophoresis. All cell types showed typical poly (A -) peaks of 4S, 18S and 28S, corresponding to tRNA (4S) and rRNAs (18, 28S) respectively. Spermatids and spermatozoa had additional absorbance peaks at 13 and 21S which cosedimented with Xenopus oocyte mitochondrial rRNA. Patterns of incorporation of uridine and adenosine into poly (A +) RNA in all germ cell fractions tested were complex. In all cases, major areas of radioactivity were found in a broad band sedimenting between 6-17S. Spermatid fractions showed a prominent peak of incorporation at 6-8S, while pachytene cells also showed heavier poly (A +) peaks in the 17-25S region. A non-polyadenylated RNA species sedimenting at 6-8S with a relatively rapid rate of turnover was also observed in spermatids. From these results it is concluded that synthesis of transfer, ribosomal, and putative messenger RNA species continues in spermatogenic cells throughout all but the very last stages of spermatogenesis in Xenopus.

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Inhibitor induced alterations of chromatoid bodies in male germ line cells of Xenopus laevis

Cited by 7 publications

References 22 publications

SMG6 localizes to the chromatoid body and shapes the male germ cell transcriptome to drive spermatogenesis

SMG6 localizes to the chromatoid body and shapes the male germ cell transcriptome to drive spermatogenesis

The chromatoid body in spermatogenesis

In vitro synthesis of RNA by Xenopus spermatogenic cells. I. Evidence for polyadenylated and non‐polyadenylated RNA synthesis in different cell populations

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