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SEPTIN12 genetic variants confer susceptibility to teratozoospermia.

Lin YH, Wang YY, Chen HI, Kuo YC, Chiou YW, Lin HH, Wu CM, Hsu CC, Chiang HS, Kuo PL - PLoS ONE (2012)

Bottom Line: The variant creates a novel splice donor site that causes skipping of a portion of exon 5, resulting in a truncated protein lacking the C-terminal half of SEPTIN12.Most individuals homozygous for the c.474 A allele had teratozoospermia (abnormal sperm <14%) and their sperm showed bent tail and de-condensed nucleus with significant DNA damage.Our finding also suggests vital roles of SEPT12 in sperm nuclear integrity and tail development.

View Article: PubMed Central - PubMed

Affiliation: Graduate Institute of Basic Medicine, Fu Jen Catholic University, College of Medicine, Taipei, Taiwan.

ABSTRACT
It is estimated that 10-15% of couples are infertile and male factors account for about half of these cases. With the advent of intracytoplasmic sperm injection (ICSI), many infertile men have been able to father offspring. However, teratozoospermia still remains a big challenge to tackle. Septins belong to a family of cytoskeletal proteins with GTPase activity and are involved in various biological processes e.g. morphogenesis, compartmentalization, apoptosis and cytokinesis. SEPTIN12, identified by c-DNA microarray analysis of infertile men, is exclusively expressed in the post meiotic male germ cells. Septin12(+/+)/Septin12(+/-) chimeric mice have multiple reproductive defects including the presence of immature sperm in the semen, and sperm with bent neck (defect of the annulus) and nuclear DNA damage. These facts make SEPTIN12 a potential sterile gene in humans. In this study, we sequenced the entire coding region of SEPTIN12 in infertile men (n = 160) and fertile controls (n = 200) and identified ten variants. Among them is the c.474 G>A variant within exon 5 that encodes part of the GTP binding domain. The variant creates a novel splice donor site that causes skipping of a portion of exon 5, resulting in a truncated protein lacking the C-terminal half of SEPTIN12. Most individuals homozygous for the c.474 A allele had teratozoospermia (abnormal sperm <14%) and their sperm showed bent tail and de-condensed nucleus with significant DNA damage. Ex vivo experiment showed truncated SEPT12 inhibits filament formation in a dose-dependent manner. This study provides the first causal link between SEPTIN12 genetic variant and male infertility with distinctive sperm pathology. Our finding also suggests vital roles of SEPT12 in sperm nuclear integrity and tail development.

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Expression patterns of SEPT12 human male germ cells with the c.474G/G (wild) and c.474A/A genotypes.(A.) Detection of SEPT12 signals during human spermiogenesis. (a.–a′): Round Spermatids (RS), (b.–b′) Elongating Spermatids (ES) and Mature Sperm (MS). Left: SEPT12 signal (green); Right: merge of SEPT12 (green) and DAPI (light blue) signals. (B.) Varied type of spermatozoa isolated from cases with the c.474A/A genotype. Left: SEPT12 signal (green); Right: merge of SEPT12 (green) and DAPI (light blue) signals (Magnification: ×1,000).
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pone-0034011-g005: Expression patterns of SEPT12 human male germ cells with the c.474G/G (wild) and c.474A/A genotypes.(A.) Detection of SEPT12 signals during human spermiogenesis. (a.–a′): Round Spermatids (RS), (b.–b′) Elongating Spermatids (ES) and Mature Sperm (MS). Left: SEPT12 signal (green); Right: merge of SEPT12 (green) and DAPI (light blue) signals. (B.) Varied type of spermatozoa isolated from cases with the c.474A/A genotype. Left: SEPT12 signal (green); Right: merge of SEPT12 (green) and DAPI (light blue) signals (Magnification: ×1,000).

Mentions: To determine whether del-SEPT12 also affects terminal differentiation of male germ cells in humans, spermatozoa were isolated from the testis biopsies of fertile controls with c.474C/C and infertile men with c.474A/A. IFA showed that in fertile men, SEPT12 is present around the nuclear periphery of round spermatids, at the neck region of elongating spermatids, and at the neck region and annulus of mature spermatozoa (Figure 5A), a finding in accord with our previously report [33]. In germ cells isolated from infertile men who carried c.477A/A, SEPT12 showed a dot-like pattern in differential stages of haploid germ cells (Figure 5B). This finding is in accord with the expression pattern of SEPT12-del-EGFP in NT2D1 cells (Figure 4B and 4D).


SEPTIN12 genetic variants confer susceptibility to teratozoospermia.

Lin YH, Wang YY, Chen HI, Kuo YC, Chiou YW, Lin HH, Wu CM, Hsu CC, Chiang HS, Kuo PL - PLoS ONE (2012)

Expression patterns of SEPT12 human male germ cells with the c.474G/G (wild) and c.474A/A genotypes.(A.) Detection of SEPT12 signals during human spermiogenesis. (a.–a′): Round Spermatids (RS), (b.–b′) Elongating Spermatids (ES) and Mature Sperm (MS). Left: SEPT12 signal (green); Right: merge of SEPT12 (green) and DAPI (light blue) signals. (B.) Varied type of spermatozoa isolated from cases with the c.474A/A genotype. Left: SEPT12 signal (green); Right: merge of SEPT12 (green) and DAPI (light blue) signals (Magnification: ×1,000).
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3316533&req=5

pone-0034011-g005: Expression patterns of SEPT12 human male germ cells with the c.474G/G (wild) and c.474A/A genotypes.(A.) Detection of SEPT12 signals during human spermiogenesis. (a.–a′): Round Spermatids (RS), (b.–b′) Elongating Spermatids (ES) and Mature Sperm (MS). Left: SEPT12 signal (green); Right: merge of SEPT12 (green) and DAPI (light blue) signals. (B.) Varied type of spermatozoa isolated from cases with the c.474A/A genotype. Left: SEPT12 signal (green); Right: merge of SEPT12 (green) and DAPI (light blue) signals (Magnification: ×1,000).
Mentions: To determine whether del-SEPT12 also affects terminal differentiation of male germ cells in humans, spermatozoa were isolated from the testis biopsies of fertile controls with c.474C/C and infertile men with c.474A/A. IFA showed that in fertile men, SEPT12 is present around the nuclear periphery of round spermatids, at the neck region of elongating spermatids, and at the neck region and annulus of mature spermatozoa (Figure 5A), a finding in accord with our previously report [33]. In germ cells isolated from infertile men who carried c.477A/A, SEPT12 showed a dot-like pattern in differential stages of haploid germ cells (Figure 5B). This finding is in accord with the expression pattern of SEPT12-del-EGFP in NT2D1 cells (Figure 4B and 4D).

Bottom Line: The variant creates a novel splice donor site that causes skipping of a portion of exon 5, resulting in a truncated protein lacking the C-terminal half of SEPTIN12.Most individuals homozygous for the c.474 A allele had teratozoospermia (abnormal sperm <14%) and their sperm showed bent tail and de-condensed nucleus with significant DNA damage.Our finding also suggests vital roles of SEPT12 in sperm nuclear integrity and tail development.

View Article: PubMed Central - PubMed

Affiliation: Graduate Institute of Basic Medicine, Fu Jen Catholic University, College of Medicine, Taipei, Taiwan.

ABSTRACT
It is estimated that 10-15% of couples are infertile and male factors account for about half of these cases. With the advent of intracytoplasmic sperm injection (ICSI), many infertile men have been able to father offspring. However, teratozoospermia still remains a big challenge to tackle. Septins belong to a family of cytoskeletal proteins with GTPase activity and are involved in various biological processes e.g. morphogenesis, compartmentalization, apoptosis and cytokinesis. SEPTIN12, identified by c-DNA microarray analysis of infertile men, is exclusively expressed in the post meiotic male germ cells. Septin12(+/+)/Septin12(+/-) chimeric mice have multiple reproductive defects including the presence of immature sperm in the semen, and sperm with bent neck (defect of the annulus) and nuclear DNA damage. These facts make SEPTIN12 a potential sterile gene in humans. In this study, we sequenced the entire coding region of SEPTIN12 in infertile men (n = 160) and fertile controls (n = 200) and identified ten variants. Among them is the c.474 G>A variant within exon 5 that encodes part of the GTP binding domain. The variant creates a novel splice donor site that causes skipping of a portion of exon 5, resulting in a truncated protein lacking the C-terminal half of SEPTIN12. Most individuals homozygous for the c.474 A allele had teratozoospermia (abnormal sperm <14%) and their sperm showed bent tail and de-condensed nucleus with significant DNA damage. Ex vivo experiment showed truncated SEPT12 inhibits filament formation in a dose-dependent manner. This study provides the first causal link between SEPTIN12 genetic variant and male infertility with distinctive sperm pathology. Our finding also suggests vital roles of SEPT12 in sperm nuclear integrity and tail development.

Show MeSH
Related in: MedlinePlus