Small Noncoding RNAs in Reproduction and Infertility

Infertility has been reported as one of the most common reproductive impairments, affecting nearly one in six couples worldwide. A large proportion of infertility cases are diagnosed as idiopathic, signifying a deficit in information surrounding the pathology of infertility and necessity of medical intervention such as assisted reproductive therapy. Small noncoding RNAs (sncRNAs) are well-established regulators of mammalian reproduction. Advanced technologies have revealed the dynamic expression and diverse functions of sncRNAs during mammalian germ cell development. Mounting evidence indicates sncRNAs in sperm, especially microRNAs (miRNAs) and transfer RNA (tRNA)-derived small RNAs (tsRNAs), are sensitive to environmental changes and mediate the inheritance of paternally acquired metabolic and mental traits. Here, we review the critical roles of sncRNAs in mammalian germ cell development. Furthermore, we highlight the functions of sperm-borne sncRNAs in epigenetic inheritance. We also discuss evidence supporting sncRNAs as promising biomarkers for fertility and embryo quality in addition to the present limitations of using sncRNAs for infertility diagnosis and treatment.

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Long noncoding RNAs in spermatogenesis: insights from recent high-throughput transcriptome studies

Reproduction ◽

10.1530/rep-13-0594 ◽

2014 ◽

Vol 147 (5) ◽

pp. R131-R141 ◽

Cited By ~ 60

Author(s):

Alfred Chun-Shui Luk ◽

Wai-Yee Chan ◽

Owen M Rennert ◽

Tin-Lap Lee

Keyword(s):

Germ Cell ◽

Developmental Process ◽

Noncoding Rnas ◽

Transcriptome Profiling ◽

Cell Development ◽

Male Germ Cell ◽

Specific Gene ◽

Protein Coding ◽

Germ Cell Development ◽

Protein Coding Genes

Spermatogenesis is a complex developmental process in which undifferentiated spermatogonia are differentiated into spermatocytes and spermatids through two rounds of meiotic division and finally giving rise to mature spermatozoa (sperm). These processes involve many testis- or male germ cell-specific gene products that undergo strict developmental regulations. As a result, identifying critical, regulatory genes controlling spermatogenesis provide the clues not only to the regulatory mechanism of spermatogenesis at the molecular level, but also to the identification of candidate genes for infertility or contraceptives development. Despite the biological importance in male germ cell development, the underlying mechanisms of stage-specific gene regulation and cellular transition during spermatogenesis remain largely elusive. Previous genomic studies on transcriptome profiling were largely limited to protein-coding genes. Importantly, protein-coding genes only account for a small percentage of transcriptome; the majority are noncoding transcripts that do not translate into proteins. Although small noncoding RNAs (ncRNAs) such as microRNAs, siRNAs, and Piwi-interacting RNAs are extensively investigated in male germ cell development, the role of long ncRNAs (lncRNAs), commonly defined as ncRNAs longer than 200 bp, is relatively unexplored. Herein, we summarize recent transcriptome studies on spermatogenesis and show examples that a subset of noncoding transcript population, known as lncRNAs, constitutes a novel regulatory target in spermatogenesis.

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