Protein tyrosine phosphatase non-receptor type 14 is a novel sperm-motility biomarker

Abstract

Purpose To understand the molecular basis of spermmotility and to identify related novel motility biomarkers. Methods Two-dimensional electrophoresis (2DE) followed by Reverse-phase-nano-high-performance liquid chromatography-electrospray ionization tandem mass spectrometry (RP-nano-HPLC-ESI-MS/MS) were applied to establish the human sperm proteome. Then the sperm proteome of moderate-motile human sperm fraction and that of good-motile human sperm fraction from pooled spermatozoa of forty normozoospermic donors (Group 1 subjects) were compared to identify the dysregulated proteins. Among these down-regulated proteins, Protein tyrosine phosphatase non-receptor type 14 (PTPN14) was chosen to reconfirm by Western blotting and semiquantitative reverse transcription polymerase chain reaction. For clinical application, Western blotting and real-time reverse transcription polymerase chain reaction was performed to compare the expression level of PTPN14 in (Group 2 subjects) nine normozoospermic controls and thirty-three asthenozoospermic patients (including 21 mild asthenozoospermic cases and 12 severe cases). Finally, bioinformatic tools prediction and immunofluorescence assay were performed to elucidate the potential localization of PTPN14. Results The expression levels of three proteins were observed to be lower in the moderate-motile sperm fraction than in good-motile sperm of group 1 subjects. Among three proteins with persistent down-regulation in the moderate-motile sperm, we reconfirmed that the expression level of PTPN14 was significantly lower in both mRNA and protein levels from the moderate-motile sperm fraction. Further, down-regulation of PTPN14 was found at the translational and transcriptional level in the asthenozoospermic men. Finally, Bioinformatic tools prediction and immunofluorescence assay showed that PTPN14 maybe predominantly localized at the mitochondria in the midpiece of human ejaculated sperm. Conclusions Proteomics tools were applied to identify three possible sperm motility-related proteins. Among these proteins, PTPN14 was highly likely a novel spermmotility biomarker and a potential mitochondrial protein.Capsule Protein tyrosine phosphatase non-receptor type 14 is a novel sperm-motility biomarker proven by proteomic tools.Electronic supplementary material The online version of this article

Characterization of 3-hydroxyisobutyrate dehydrogenase, HIBADH, as a sperm-motility marker

“…Thus, adequate sperm motility is vital for successful fertilization [43]. Our previous study focused on proteomic profiles of spoor-motility spermatozoa [32]. Approximately 300 areas were resolved in a 2D map in pH values ranging from 4 to 7.…”

“…1) [32]. HIBADH is an NAD + -dependent enzyme that catalyzes the reversible oxidation of 3-hydroxyisobutyrate to methylmalonate semialdehyde in valine catabolism in the gluconeogenesis pathway.…”

“…A modified proteomic method, difference 2D gel electrophoresis, was developed to analyze post-translational modification of proteins during sperm maturation [26]. Using this powerful approach, several studies, including ours, have revealed a growing list of proteins that may be involved in regulating sperm motility [27][28][29][30][31][32].…”

“…In our previous study, one metabolism-related protein, 3-hydroxyisobutyrate dehydrogenase (HIBADH; EC 1.1.1.31), which is one of the critical enzymes generating glucose by metabolizing amino acids in the gluconeogenesis pathway, was identified [32]. HIBADH belongs to the family of oxidoreductases, specifically those acting on the CH-OH group of donors with NAD + or NADP + acceptors [33,34].…”

PTPN14 (protein tyrosine phosphatase, non-receptor type 14)

“…Catalytic PTP domain: the crystal structure of the PTPN14 catalytic C-terminal PTP domain has been solved (Barr et al, 2006 (Liu et al, 2013;Poernbacher et al, 2012). Mitochondrial localisation signal: PTPN14 contains a putative mitochondrial localisation signal (MitoProt II), and may be localised to mitochondria in some cell types (Chao et al, 2011).…”