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Selfish spermatogonial selection: evidence from an immunohistochemical screen in testes of elderly men.

Lim J, Maher GJ, Turner GD, Dudka-Ruszkowska W, Taylor S, Rajpert-De Meyts E, Goriely A, Wilkie AO - PLoS ONE (2012)

Bottom Line: The dominant congenital disorders Apert syndrome, achondroplasia and multiple endocrine neoplasia-caused by specific missense mutations in the FGFR2, FGFR3 and RET proteins respectively-represent classical examples of paternal age-effect mutation, a class that arises at particularly high frequencies in the sperm of older men.We found numerous small (less than 200 cells) cellular aggregations with distinct immunohistochemical characteristics, localised to a portion of the seminiferous tubule, which are of uncertain significance.However more infrequently we identified additional regions where entire seminiferous tubules had a circumferentially altered immunohistochemical appearance that extended through multiple serial sections that were physically contiguous (up to 1 mm in length), and exhibited enhanced staining for antibodies both to FGFR3 and a marker of downstream signal activation, pAKT.

View Article: PubMed Central - PubMed

Affiliation: Clinical Genetics Group, Weatherall Institute of Molecular Medicine, University of Oxford, Oxford, United Kingdom.

ABSTRACT
The dominant congenital disorders Apert syndrome, achondroplasia and multiple endocrine neoplasia-caused by specific missense mutations in the FGFR2, FGFR3 and RET proteins respectively-represent classical examples of paternal age-effect mutation, a class that arises at particularly high frequencies in the sperm of older men. Previous analyses of DNA from randomly selected cadaveric testes showed that the levels of the corresponding FGFR2, FGFR3 and RET mutations exhibit very uneven spatial distributions, with localised hotspots surrounded by large mutation-negative areas. These studies imply that normal testes are mosaic for clusters of mutant cells: these clusters are predicted to have altered growth and signalling properties leading to their clonal expansion (selfish spermatogonial selection), but DNA extraction eliminates the possibility to study such processes at a tissue level. Using a panel of antibodies optimised for the detection of spermatocytic seminoma, a rare tumour of spermatogonial origin, we demonstrate that putative clonal events are frequent within normal testes of elderly men (mean age: 73.3 yrs) and can be classed into two broad categories. We found numerous small (less than 200 cells) cellular aggregations with distinct immunohistochemical characteristics, localised to a portion of the seminiferous tubule, which are of uncertain significance. However more infrequently we identified additional regions where entire seminiferous tubules had a circumferentially altered immunohistochemical appearance that extended through multiple serial sections that were physically contiguous (up to 1 mm in length), and exhibited enhanced staining for antibodies both to FGFR3 and a marker of downstream signal activation, pAKT. These findings support the concept that populations of spermatogonia in individual seminiferous tubules in the testes of older men are clonal mosaics with regard to their signalling properties and activation, thus fulfilling one of the specific predictions of selfish spermatogonial selection.

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Examples of microclones in samples 2–1 and 3–1.A. Microclone 2–1_C40, located away from the basal lamina, is positive for MAGEA4 and OCT2 (single cell identified post hoc) but not for FGFR3. B. Microclone 3–1_C1, located within the lumen of the tubule is positive for MAGEA4, FGFR3 and OCT2 (2 cells identified post hoc). Panels above the set of images show the markers used to stain the sections and the analysis of the results, using the same scheme as in legend to Figure 2. Scale bars: 100 µm.
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pone-0042382-g003: Examples of microclones in samples 2–1 and 3–1.A. Microclone 2–1_C40, located away from the basal lamina, is positive for MAGEA4 and OCT2 (single cell identified post hoc) but not for FGFR3. B. Microclone 3–1_C1, located within the lumen of the tubule is positive for MAGEA4, FGFR3 and OCT2 (2 cells identified post hoc). Panels above the set of images show the markers used to stain the sections and the analysis of the results, using the same scheme as in legend to Figure 2. Scale bars: 100 µm.

Mentions: Having established a robust methodology to survey testes for microclones and identified many such events within two different regions of a single testis, we then screened portions of testes from 5 other men aged 69 to 78 years (Table 1) to determine whether these findings were peculiar to the original sample, or whether similar features could be identified more generally in testes of elderly men. Figures 3A and B illustrate further examples of microclones from two different testes, and Table 3 summarises the findings. Although the apparent prevalence of these microclones varied at least 10-fold between testes (Table 3), their occurrence in those aged over 69 years seems to be a widespread and general phenomenon.


Selfish spermatogonial selection: evidence from an immunohistochemical screen in testes of elderly men.

Lim J, Maher GJ, Turner GD, Dudka-Ruszkowska W, Taylor S, Rajpert-De Meyts E, Goriely A, Wilkie AO - PLoS ONE (2012)

Examples of microclones in samples 2–1 and 3–1.A. Microclone 2–1_C40, located away from the basal lamina, is positive for MAGEA4 and OCT2 (single cell identified post hoc) but not for FGFR3. B. Microclone 3–1_C1, located within the lumen of the tubule is positive for MAGEA4, FGFR3 and OCT2 (2 cells identified post hoc). Panels above the set of images show the markers used to stain the sections and the analysis of the results, using the same scheme as in legend to Figure 2. Scale bars: 100 µm.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3412839&req=5

pone-0042382-g003: Examples of microclones in samples 2–1 and 3–1.A. Microclone 2–1_C40, located away from the basal lamina, is positive for MAGEA4 and OCT2 (single cell identified post hoc) but not for FGFR3. B. Microclone 3–1_C1, located within the lumen of the tubule is positive for MAGEA4, FGFR3 and OCT2 (2 cells identified post hoc). Panels above the set of images show the markers used to stain the sections and the analysis of the results, using the same scheme as in legend to Figure 2. Scale bars: 100 µm.
Mentions: Having established a robust methodology to survey testes for microclones and identified many such events within two different regions of a single testis, we then screened portions of testes from 5 other men aged 69 to 78 years (Table 1) to determine whether these findings were peculiar to the original sample, or whether similar features could be identified more generally in testes of elderly men. Figures 3A and B illustrate further examples of microclones from two different testes, and Table 3 summarises the findings. Although the apparent prevalence of these microclones varied at least 10-fold between testes (Table 3), their occurrence in those aged over 69 years seems to be a widespread and general phenomenon.

Bottom Line: The dominant congenital disorders Apert syndrome, achondroplasia and multiple endocrine neoplasia-caused by specific missense mutations in the FGFR2, FGFR3 and RET proteins respectively-represent classical examples of paternal age-effect mutation, a class that arises at particularly high frequencies in the sperm of older men.We found numerous small (less than 200 cells) cellular aggregations with distinct immunohistochemical characteristics, localised to a portion of the seminiferous tubule, which are of uncertain significance.However more infrequently we identified additional regions where entire seminiferous tubules had a circumferentially altered immunohistochemical appearance that extended through multiple serial sections that were physically contiguous (up to 1 mm in length), and exhibited enhanced staining for antibodies both to FGFR3 and a marker of downstream signal activation, pAKT.

View Article: PubMed Central - PubMed

Affiliation: Clinical Genetics Group, Weatherall Institute of Molecular Medicine, University of Oxford, Oxford, United Kingdom.

ABSTRACT
The dominant congenital disorders Apert syndrome, achondroplasia and multiple endocrine neoplasia-caused by specific missense mutations in the FGFR2, FGFR3 and RET proteins respectively-represent classical examples of paternal age-effect mutation, a class that arises at particularly high frequencies in the sperm of older men. Previous analyses of DNA from randomly selected cadaveric testes showed that the levels of the corresponding FGFR2, FGFR3 and RET mutations exhibit very uneven spatial distributions, with localised hotspots surrounded by large mutation-negative areas. These studies imply that normal testes are mosaic for clusters of mutant cells: these clusters are predicted to have altered growth and signalling properties leading to their clonal expansion (selfish spermatogonial selection), but DNA extraction eliminates the possibility to study such processes at a tissue level. Using a panel of antibodies optimised for the detection of spermatocytic seminoma, a rare tumour of spermatogonial origin, we demonstrate that putative clonal events are frequent within normal testes of elderly men (mean age: 73.3 yrs) and can be classed into two broad categories. We found numerous small (less than 200 cells) cellular aggregations with distinct immunohistochemical characteristics, localised to a portion of the seminiferous tubule, which are of uncertain significance. However more infrequently we identified additional regions where entire seminiferous tubules had a circumferentially altered immunohistochemical appearance that extended through multiple serial sections that were physically contiguous (up to 1 mm in length), and exhibited enhanced staining for antibodies both to FGFR3 and a marker of downstream signal activation, pAKT. These findings support the concept that populations of spermatogonia in individual seminiferous tubules in the testes of older men are clonal mosaics with regard to their signalling properties and activation, thus fulfilling one of the specific predictions of selfish spermatogonial selection.

Show MeSH
Related in: MedlinePlus