Low long non-coding RNA HOTAIR expression is associated with down-regulation of Nrf2 in the spermatozoa of patients with asthenozoospermia or oligoasthenozoospermia

Abstract

HOTAIR, a long noncoding RNA, regulates development and progression of tumor cells and function of normal stem cells. However, the role and the molecular mechanism of HOTAIR in the spermatozoa of patients with asthenozoospermia and oligoasthenozoospermia are still unclear. Herein, 45 healthy control, 45 asthenozoospermic patients and 45 oligoasthenozoospermic patients were enrolled. Initially, through analyzing HOTAIR expression, we observed a decreased level of HOTAIR expression in patients. Subsequently, we found that there was a positive correlation between HOTAIR expression and Nrf2 expression in patients. The low expression of HOTAIR was also observed to be associated with specific sperm function parameters, including motility and vitality. In the ejaculated spermatozoa from patients, low level of histone H4 acetylation of the Nrf2 gene promoter was observed. Finally, we found that downregulation of HOTAIR expression reduced histone H4 acetylation in Nrf2 promoter and Nrf2 expression. Therefore, this study demonstrated that HOTAIR expression was low in the spermatozoa of patients with asthenozoospermia and oligoasthenozoospermia, which resulted in down-regulation of Nrf2 expression. Our data suggested the decrease of HOTAIR expression led to ROS related defects in sperm function.

Keywords: HOTAIR; Nrf2; ROS; asthenozoospermia and oligoasthenozoospermia; histone acetylation.

Figure 1

Low expression of HOTAIR and Nrf2 in the ejaculated spermatozoa from asthenozoospermic and oligoasthenozoospermic patients. HOTAIR (A) and Nrf2 (B) expression levels were obviously reduced in the samples from asthenozoospermic patients and oligoasthenozoospermic patients compared to those from healthy control. **P < 0.01, indicate significant differences from the healthy control groups. con: healthy control, ast: asthenozoospermic patients, oli: oligoasthenozoospermic patients.

Figure 2

HOTAIR expression levels were positively correlated with Nrf2 expression level and SOD activity. Spearman’s correlation analysis revealed that there was a significant positive correlation between HOTAIR expression level and Nrf2 expression level in asthenozoospermic patients (A) and in oligoasthenozoospermic patients (B). Significant positive correlations were also observed between HOTAIR expression level and SOD activity in asthenozoospermic patients (C) and in oligoasthenozoospermic patients (D).

Figure 3

Low level of histone H4 acetylation of the Nrf2 gene promoter in the ejaculated spermatozoa from asthenozoospermic and oligoasthenozoospermic patients. ChIP-qPCR assay revealed that histone H4 acetylation in Nrf2 promoter was significantly decreased in ejaculated spermatozoa from asthenozoospermic and oligoasthenozoospermic patients. **P < 0.01, indicate significant differences from the healthy control groups. con: healthy control, ast: asthenozoospermic patients, oli: oligoasthenozoospermic patients.

Figure 4

Silence HOTAIR inhibited Nrf2 expression and SOD activity in spermatocytes. GC1-spg cells were transfected with si-HOTAIR (100 nM) for 48 h, the HOTAIR expression (A), Nrf2 mRNA and protein expression (B) and SOD activity (C) were obviously decreased. **P < 0.01, indicate significant differences from the respective control groups.

Figure 5

Silence HOTAIR inhibited level of histone H4 acetylation in the Nrf2 gene promoter. ChIP-qPCR assay revealed that silence HOTAIR significantly suppressed the level of histone H4 acetylation in the Nrf2 gene promoter. **P < 0.01, indicate significant differences from the respective control groups.