Micro-RNAs, next-generation molecular markers in male infertility field.

The prevalence of male infertility appraised 10-15% in worldwide. Male infertility is frequently coupled to deficient in sperm development and production (1). Of note, in principle of the number of sperm cells in seminal fluid, has been categorised in azoospermia, severe oligozoospermia and mild oligozoospermia. In azoospermia condition, a sperm cell counts approximately ≤5×106 cells/mL, and in severe oligozoospermia and mild oligozoospermia, sperm cell counts >5×106 cells/mL and <20×106 cells/mL respectively (2). Male infertility is a multi-factorial syndrome accompanied a broad category of disorders. Moreover, until several decades, investigators endeavor to reveal the molecular procedures of male infertility, although the most aspects remain a clinical obstacle. Interestingly, the cause of infertility in more than 50% of infertile men is undiscovered. In generally, the known causes of male infertility are categories in genetic and environmental conditions. The genetic abnormalities are involving, numerical and structural chromosomal in sufferers for oligozoospermia and azoospermia (3,4). Routinely; the diagnosis of male infertility can be supported by assessment of microdeletions that occurred in the long arm of the Y chromosome (Yq) especially in azoospermia factor (AZF) regions (5,6). As previously an investigation in this filed revealed that, the frequency of these microdeletions in azoospermia and severe oligozoospermia men are approximately 13% and 1-7% respectively (7). Notwithstanding, the Y chromosome microdeletions consideration can be customarily be proposed to each of men with azoospermia and severe oligozoospermia. Although in more than cases, they are not powerful tolls to explore all of factors that leading to infertility. Furthermore, we need to introduce a new biomolecular marker for consideration of infertile men with the cause of unexplained. Currently, the results of several investigators have been suggesting that with providing of miRNAs expression patterns, it possibly that a benefit to reveal of causes of the infertile men unexplained. However, the results of authors revealed that miRNAs play strictly roles in post-transcriptional and post-translational regulatory in several biological procedures (8). The miRNAs are involvement in several of reproductive processes such as embryogenesis, oogenesis, and spermatogenesis (9,10). Here, I summarize a short overview in recent studies revealed that dysregulation in miRNAs expression’s patterns, leading to defective sperm production (11-16) (). In generally, in mammalian spermatogenesis, miRNAs plays an important impact in development of spermatozoa, particularly in germ cells and somatic cells (17). However, It is conceivable that for any up-regulation and down-regulation in miRNAs expression patterns, significantly affecting in spermatogenesis pathways and leading to several types of reproduction abnormalities (18,19). Importantly, the spermatogenetic disturbance is the most common feature of male-factor infertility, but it is not complete explained of causes. Furthermore, with considering the important role of miRNAs in spermatogenesis, it has potential to provide and development expression profile of miRNAs in different conditionals of infertility. Finally, it is possible that using of the measurement expression pattern’s of these molecules in the seminal fluids; introduce as a novel biomolecular marker for consideration and determination of idiopathic infertility patients.

Table 1

The short overview of recent studies that worked on patterns miRNAs dysregulation in azoospermic or idiopathic infertile patients

Abnormality type	Locations	Up-regulation	Ref	Down-regulation	Locations	Ref
Azoermia/Idiopathic infertile men	4q25	hsa-mir-302a	(12)	hsa-mir-34c-5p	11q23.1	(13,16)
	9p21.3	hsa-mir-491-3p		hsa-mir-122	18q21.31
				hsa-mir-146b-5p	10q24.32
				hsa-mir-509-5p	Xq27.3
	4	hsa-mir-574-5p	(15)	hsa-mir-29c	1q32.2	(12)
	4q25	hsa-mir-297		hsa-mir-34b	11q23.1
	18q21.31	hsa-mir-122		hsa-mir-520d-3p	19
	6	hsa-mir-1275		hsa-mir-383	8p22
	19q13.42	hsa-mir-373
	22q11.21	hsa-mir-185
	16p13.12	hsa-mir-193b		hsa-mir-383	8p22	(11)
	13q31.3	miR-19b	(14)	hsa-mir-100	11q24.1	(15)
	-	let-7a		hsa-mir-512-3p	19q13.42
				hsa-mir-16	16p12-p11.2
				hsa-mir-23b	9q22.32
				hsa-mir-26a-1	3p22.2