Ssm1b expression and function in germ cells of adult mice and in early embryos

Sarayu Ratnam; Grazyna Bozek; Terence Martin; Shannon J. Gallagher; Christopher J. Payne; Ursula Storb

doi:10.1002/mrd.22826

Ssm1b expression and function in germ cells of adult mice and in early embryos

Sarayu Ratnam^*, Grazyna Bozek, Terence Martin, Shannon J. Gallagher, Christopher J. Payne, Ursula Storb

^*Corresponding author for this work

Research output: Contribution to journal › Article › peer-review

4 Scopus citations

Abstract

Ssm1b (Strain-specific modifier of DNA methylation 1b) is a Krüppel-associated box (KRAB) zinc finger gene that promotes CpG methylation in the mouse transgene HRD (Heavy chain enhancer, rearrangement by deletion). We report here that Ssm1b expression and concomitant HRD methylation are also present in the male and female germ cells of adult mice. Ssm1b is expressed in both diploid (2N) and haploid (1N) oocytes, as well as in 1N spermatids and spermatozoa, but not in 2N spermatogonia. Interestingly, Ssm1b mRNA is not detected in any other adult mouse organ examined, although Ssm1-family mRNAs are highly expressed in the heart. Reflecting strain specificity, Ssm1b expression and HRD methylation are not observed in early-stage C3H/HeJ mouse embryos; however, an Ssm1b-like gene that closely resembles an Ssm1b-like gene previously found in wild-derived mice is expressed in cultured embryonic stem cells derived from C3H/HeJ embryos, suggesting that culture conditions affect its expression. Collectively, this work demonstrates that HRD methylation by Ssm1b is more temporally restricted during spermatogenesis compared to oogenesis, and is altered when embryonic stem cells are cultured from C3H/HeJ inner cell mass cells.

Original language	English (US)
Pages (from-to)	596-613
Number of pages	18
Journal	Molecular reproduction and development
Volume	84
Issue number	7
DOIs	https://doi.org/10.1002/mrd.22826
State	Published - Jul 2017

Funding

The authors wish to thank Dan Nicolae, Department of Medicine, University of Chicago for performing the statistical analysis; William Buikema, DNA sequencing facility, University of Chicago for the DNA sequencing; Tara Payton of the Centre for Applied Genomics, The Hospital for Sick Children, Toronto, Canada for assistance with the speed congenics; the Northwestern University—Flow Cytometry Core Facility supported by Cancer Center Support Grant (NCI CA060553) for FACS analysis and cell sorting; Francesca Duncan for her help with oocyte collection from the ovaries; and Peter Engler for critical review of the manuscript. The studies were supported by National Institutes of Health (NIH) grants (RO3HD05827 and AI047380) and a Pilot Project grant from the University of Chicago Cancer Research Center to U.S. Support for S.R was by a fellowship from the Cancer Research Institute. C.P. is funded BY NIH grant U01HD084046. The authors declare no conflict of interest.

Keywords

DNA methylation
ES cells
KRAB zinc finger gene

ASJC Scopus subject areas

Genetics
Cell Biology
Developmental Biology

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title = "Ssm1b expression and function in germ cells of adult mice and in early embryos",

abstract = "Ssm1b (Strain-specific modifier of DNA methylation 1b) is a Kr{\"u}ppel-associated box (KRAB) zinc finger gene that promotes CpG methylation in the mouse transgene HRD (Heavy chain enhancer, rearrangement by deletion). We report here that Ssm1b expression and concomitant HRD methylation are also present in the male and female germ cells of adult mice. Ssm1b is expressed in both diploid (2N) and haploid (1N) oocytes, as well as in 1N spermatids and spermatozoa, but not in 2N spermatogonia. Interestingly, Ssm1b mRNA is not detected in any other adult mouse organ examined, although Ssm1-family mRNAs are highly expressed in the heart. Reflecting strain specificity, Ssm1b expression and HRD methylation are not observed in early-stage C3H/HeJ mouse embryos; however, an Ssm1b-like gene that closely resembles an Ssm1b-like gene previously found in wild-derived mice is expressed in cultured embryonic stem cells derived from C3H/HeJ embryos, suggesting that culture conditions affect its expression. Collectively, this work demonstrates that HRD methylation by Ssm1b is more temporally restricted during spermatogenesis compared to oogenesis, and is altered when embryonic stem cells are cultured from C3H/HeJ inner cell mass cells.",

keywords = "DNA methylation, ES cells, KRAB zinc finger gene",

author = "Sarayu Ratnam and Grazyna Bozek and Terence Martin and Gallagher, {Shannon J.} and Payne, {Christopher J.} and Ursula Storb",

note = "Funding Information: The authors wish to thank Dan Nicolae, Department of Medicine, University of Chicago for performing the statistical analysis; William Buikema, DNA sequencing facility, University of Chicago for the DNA sequencing; Tara Payton of the Centre for Applied Genomics, The Hospital for Sick Children, Toronto, Canada for assistance with the speed congenics; the Northwestern University—Flow Cytometry Core Facility supported by Cancer Center Support Grant (NCI CA060553) for FACS analysis and cell sorting; Francesca Duncan for her help with oocyte collection from the ovaries; and Peter Engler for critical review of the manuscript. The studies were supported by National Institutes of Health (NIH) grants (RO3HD05827 and AI047380) and a Pilot Project grant from the University of Chicago Cancer Research Center to U.S. Support for S.R was by a fellowship from the Cancer Research Institute. C.P. is funded BY NIH grant U01HD084046. The authors declare no conflict of interest. Publisher Copyright: {\textcopyright} 2017 Wiley Periodicals, Inc.",

year = "2017",

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AU - Payne, Christopher J.

AU - Storb, Ursula

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N2 - Ssm1b (Strain-specific modifier of DNA methylation 1b) is a Krüppel-associated box (KRAB) zinc finger gene that promotes CpG methylation in the mouse transgene HRD (Heavy chain enhancer, rearrangement by deletion). We report here that Ssm1b expression and concomitant HRD methylation are also present in the male and female germ cells of adult mice. Ssm1b is expressed in both diploid (2N) and haploid (1N) oocytes, as well as in 1N spermatids and spermatozoa, but not in 2N spermatogonia. Interestingly, Ssm1b mRNA is not detected in any other adult mouse organ examined, although Ssm1-family mRNAs are highly expressed in the heart. Reflecting strain specificity, Ssm1b expression and HRD methylation are not observed in early-stage C3H/HeJ mouse embryos; however, an Ssm1b-like gene that closely resembles an Ssm1b-like gene previously found in wild-derived mice is expressed in cultured embryonic stem cells derived from C3H/HeJ embryos, suggesting that culture conditions affect its expression. Collectively, this work demonstrates that HRD methylation by Ssm1b is more temporally restricted during spermatogenesis compared to oogenesis, and is altered when embryonic stem cells are cultured from C3H/HeJ inner cell mass cells.

AB - Ssm1b (Strain-specific modifier of DNA methylation 1b) is a Krüppel-associated box (KRAB) zinc finger gene that promotes CpG methylation in the mouse transgene HRD (Heavy chain enhancer, rearrangement by deletion). We report here that Ssm1b expression and concomitant HRD methylation are also present in the male and female germ cells of adult mice. Ssm1b is expressed in both diploid (2N) and haploid (1N) oocytes, as well as in 1N spermatids and spermatozoa, but not in 2N spermatogonia. Interestingly, Ssm1b mRNA is not detected in any other adult mouse organ examined, although Ssm1-family mRNAs are highly expressed in the heart. Reflecting strain specificity, Ssm1b expression and HRD methylation are not observed in early-stage C3H/HeJ mouse embryos; however, an Ssm1b-like gene that closely resembles an Ssm1b-like gene previously found in wild-derived mice is expressed in cultured embryonic stem cells derived from C3H/HeJ embryos, suggesting that culture conditions affect its expression. Collectively, this work demonstrates that HRD methylation by Ssm1b is more temporally restricted during spermatogenesis compared to oogenesis, and is altered when embryonic stem cells are cultured from C3H/HeJ inner cell mass cells.

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Ssm1b expression and function in germ cells of adult mice and in early embryos

Abstract

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