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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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Nuclear DNA damage in the spermatozoa of infertile men who carried c.474A/A.(A.–C.) The spermatozoa were stained with AO (A.), TB (B.) and AB (C.) dyes. (A.) The spermatozoa with normal (green) or abnormal nucleus (yellow). (B.–C.) Spermatozoa with normal (light blue) or abnormal (dark blue) nucleus. (Magnification: ×1,000). (D.) Quantification of the percentage of AO-, AB- or TB- stained spermatozoa. At least 100 spermatozoa cells were counted in each case (*: p<0.05; Mann-Whitney test).
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pone-0034011-g007: Nuclear DNA damage in the spermatozoa of infertile men who carried c.474A/A.(A.–C.) The spermatozoa were stained with AO (A.), TB (B.) and AB (C.) dyes. (A.) The spermatozoa with normal (green) or abnormal nucleus (yellow). (B.–C.) Spermatozoa with normal (light blue) or abnormal (dark blue) nucleus. (Magnification: ×1,000). (D.) Quantification of the percentage of AO-, AB- or TB- stained spermatozoa. At least 100 spermatozoa cells were counted in each case (*: p<0.05; Mann-Whitney test).

Mentions: Increased sperm nuclear DNA damage has been observed in abnormal sperm of Septin12+/+/Septin12+/− chimeric mice [33]. In addition, oocytes couldn't develop beyond the morula stages after IVF or ICSI using sperm obtained from the Septin12+/+/Septin12+/− chimeric mice [33]. To evaluate sperm nuclear integrity of infertile men with c.474A/A, transmission electron microscopy (TEM) and atomic force microscopy (AFM) were used. Sperm from c474A/A patients had loose nuclear matrix as examined by TEM (Figure 6A and 6B) and narrow head/de-condensed nuclear matrix as observed under AFM (Figure 6 D and E). These two classical phenotypes have been described in a previous study using AFM to examine human sperm [40]. Further, we found high percentage of sperm with nuclear DNA damage by AO, TB and AB staining (AO: P<0.05; TB: P<0.05; AB: p<0.05; by Mann-Whitney test) (Figure 7 A–D). Taken together, we found SEPT12 dysfunction caused by c.474A/A may disrupt the nuclear integrity, a finding reminiscent of that observed in the Septin12+/+/Septin12+/− chimeric mice.


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)

Nuclear DNA damage in the spermatozoa of infertile men who carried c.474A/A.(A.–C.) The spermatozoa were stained with AO (A.), TB (B.) and AB (C.) dyes. (A.) The spermatozoa with normal (green) or abnormal nucleus (yellow). (B.–C.) Spermatozoa with normal (light blue) or abnormal (dark blue) nucleus. (Magnification: ×1,000). (D.) Quantification of the percentage of AO-, AB- or TB- stained spermatozoa. At least 100 spermatozoa cells were counted in each case (*: p<0.05; Mann-Whitney test).
© Copyright Policy
Related In: Results  -  Collection

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

pone-0034011-g007: Nuclear DNA damage in the spermatozoa of infertile men who carried c.474A/A.(A.–C.) The spermatozoa were stained with AO (A.), TB (B.) and AB (C.) dyes. (A.) The spermatozoa with normal (green) or abnormal nucleus (yellow). (B.–C.) Spermatozoa with normal (light blue) or abnormal (dark blue) nucleus. (Magnification: ×1,000). (D.) Quantification of the percentage of AO-, AB- or TB- stained spermatozoa. At least 100 spermatozoa cells were counted in each case (*: p<0.05; Mann-Whitney test).
Mentions: Increased sperm nuclear DNA damage has been observed in abnormal sperm of Septin12+/+/Septin12+/− chimeric mice [33]. In addition, oocytes couldn't develop beyond the morula stages after IVF or ICSI using sperm obtained from the Septin12+/+/Septin12+/− chimeric mice [33]. To evaluate sperm nuclear integrity of infertile men with c.474A/A, transmission electron microscopy (TEM) and atomic force microscopy (AFM) were used. Sperm from c474A/A patients had loose nuclear matrix as examined by TEM (Figure 6A and 6B) and narrow head/de-condensed nuclear matrix as observed under AFM (Figure 6 D and E). These two classical phenotypes have been described in a previous study using AFM to examine human sperm [40]. Further, we found high percentage of sperm with nuclear DNA damage by AO, TB and AB staining (AO: P<0.05; TB: P<0.05; AB: p<0.05; by Mann-Whitney test) (Figure 7 A–D). Taken together, we found SEPT12 dysfunction caused by c.474A/A may disrupt the nuclear integrity, a finding reminiscent of that observed in the Septin12+/+/Septin12+/− chimeric mice.

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