INVITED COMMENTARY
Ahead of print publication  

Commentary on “Altered PIWI-LIKE 1 and PIWI-LIKE 2 mRNA expression in ejaculated spermatozoa of men with impaired sperm characteristics”


Andrology Department, Melbourne IVF and Department of Obstetrics and Gynecology, Royal Women's Hospital, The University of Melbourne, Melbourne, Victoria 3002, Australia

Date of Submission12-Nov-2017
Date of Acceptance14-Nov-2017
Date of Web Publication16-Jan-2018

Correspondence Address:
De-Yi Liu,
Andrology Department, Melbourne IVF and Department of Obstetrics and Gynecology, Royal Women’s Hospital, The University of Melbourne, Melbourne, Victoria 3002, Australia

Login to access the Email id

Source of Support: None, Conflict of Interest: None


Article in PDF

How to cite this URL:
Liu DY. Commentary on “Altered PIWI-LIKE 1 and PIWI-LIKE 2 mRNA expression in ejaculated spermatozoa of men with impaired sperm characteristics”. Asian J Androl [Epub ahead of print] [cited 2018 Feb 18]. Available from: http://www.ajandrology.com/preprintarticle.asp?id=223395



Infertility affects approximately 15% of couples who have regular intercourse with male partners for over 12-month periods, without using any contraceptives. Among these infertile couples, the male factor accounts approximately 40%–50%. A significant proportion of male infertility is due to idiopathic azoospermia, severe oligozoospermia, and teratozoospermia. While some severe male infertility is associated with possible genetic alterations in germ cell lines or spermatogenesis, the cause of severe male infertility is still largely unknown.[1],[2]

Although today the majority of severe male infertility can be treated by assisted reproductive technology (such as in vitro fertilization [IVF] and particularly intracytoplasmic sperm injection ICSI), it is still very important to investigate the underlying cause of idiopathic male infertility.

In this issue of Asian Journal of Andrology, Giebler et al.[3] reported a very good study on the relationship between mRNA expression of the four human PIWI-LIKE orthologs (PIWI-LIKE 1/HWI, PIWI-LIKE 2/HILI, PIWI-LIKE 3/HIWI3, and PIWI-LIKE 4/HIWI2) and sperm characteristics in ejaculates of 90 men with normozoospermia (n = 47) or abnormal sperm characteristics (n = 36) according to the World Health Organization (WHO) manual 5th edition. The study design and data analysis were adequate despite the relatively small sample size. The authors clearly demonstrated that PIWI-LIKE 1-4 mRNA was measurable in various proportions of ejaculated sperm samples: 9.6% for PIWI-LIKE 3, 15.7% for PIWI-LIKE 4, 49.4% for PIWI-LIKE 2, and 100% for PIWI-LIKE 1. As both PIWI-LIKE 3 and PIWI-LIKE 4 can be detected in about 10%–16% of sperm samples, the data of these two mRNAs were insufficient for statistical analysis. However, the authors found a positive correlation between PIWI-LIKE 2 mRNA expression and sperm concentration or the total number of spermatozoa/ejaculate. On the other hand, PIWI-LIKE 1 mRNA expression was negatively correlated with the percentage of total motility or progressive motility. Furthermore, PIWI-LIKE 1 mRNA expression is also negatively correlated with the proportion of nonviable spermatozoa of ejaculate from 49 men. It was interesting that both PIWI-LIKE 1 and PIWI-LIKE 2 mRNA expressions were positively correlated with male age.

In literature, it is reported that PIWI genes play an essential role in spermatogenesis, and the PIWI subfamily of genes is also involved in spermatogenesis for the maintenance and meiosis of germ line stem cells. Thus, genetic variation in PIWI genes may be potential to affect normal spermatogenesis. Mice bearing targeted mutations in PIWI genes (Miwi, Mili, and Miwi2) are sterile with distinct defects in spermatogenesis.[4] In humans, it has been demonstrated that genetic variants in PIWI-interacting RNA pathway genes confer susceptibility to spermatogenic failure which has been demonstrated in Chinese men.[5] Genetic variants in piRNA pathway genes may contribute to the risk of spermatogenesis impairment. Although the human ejaculate sperm is generally considered to contain a very small amount of mRNA, the current article by Giebler et al.[3] has clearly shown to be able to extract sufficient mRNA from ejaculated sperm.

The authors have to be congratulated for their interesting study on the association of PIWI-LIKE 1 and PIWI-LIKE 2 mRNA expression of human ejaculated sperm and sperm characteristics. A limitation of this study is the small sample size which affects the ability to analyze the relationship between sperm characteristics and PIWI-LIKE 3 and PIWI-LIKE 4; as these two mRNAs can be detected in only 10%–16% of sperm samples. Also, a more detailed analysis could be performed for PIWI-LIKE 2 as it wasonly detected in about 50% of samples. Indeed, further study with a larger sample size is required to confirm the findings and to explore the insight of the cause of impaired sperm characteristics in infertile men.


  Competing Interests Top


The author declares no competing interests.



 
  References Top

1.
Cram DS, O'Bryan MK, de Kretser DM. Male infertility genetics – the future. J Androl 2001; 22: 738–46.  Back to cited text no. 1
    
2.
Huynh T, Mollard R, Trounson A. Selected genetic factors associated with male infertility. Hum Reprod Update 2002; 8: 183–98.  Back to cited text no. 2
    
3.
Giebler M, Greither T, Müller L, Mösinger C, Behre H. Altered PIWI-LIKE 1 and PIWI-LIKE 2 mRNA expression in ejaculated spermatozoa of men with impaired sperm characteristics. Asian J Androl 2017; doi: 10.4103/aja.aja_58_17. [Epub ahead of print].  Back to cited text no. 3
    
4.
Deng W, Lin H. miwi, a murine homolog of piwi, encodes a cytoplasmic protein 342 essential for spermatogenesis. Dev Cell 2002; 2: 819–30.  Back to cited text no. 4
    
5.
Gu A, Ji G, Shi X, Long Y, Xia Y, et al. Genetic variants in Piwi-interacting RNA pathway genes confer susceptibility to spermatogenic failure in a Chinese population. Hum Reprod 2010; 25: 2955–61.  Back to cited text no. 5
    




 

 
Top
 
 
  Search
 
 Search Pubmed for
 
    -  Liu DY
Access Statistics
Email Alert *
Add to My List *
* Registration required (free)  

 
  In this article
Competing Interests
References

 Article Access Statistics
    Viewed161    
    PDF Downloaded48    

Recommend this journal