Evolutionary Conservation of Mammalian Sperm Proteins Associates with Overall, not Tyrosine, Phosphorylation in Human Spermatozoa (original) (raw)
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Sperm Phosphoproteome: Unraveling Male Infertility
Biology
Infertility affects approximately 15% of couples worldwide of childbearing age, and in many cases the etiology of male infertility is unknown. The current standard evaluation of semen is insufficient to establish an accurate diagnosis. Proteomics techniques, such as phosphoproteomics, applied in this field are a powerful tool to understand the mechanisms that regulate sperm functions such as motility, which is essential for successful fertilization. Among the post-translational modifications of sperm proteins, this review summarizes, from a proteomic perspective, the updated knowledge of protein phosphorylation, in human spermatozoa, as a relevant molecular mechanism involved in the regulation of sperm physiology. Specifically, the role of sperm protein phosphorylation in motility and, consequently, in sperm quality is highlighted. Additionally, through the analysis of published comparative phosphoproteomic studies, some candidate human sperm phosphoproteins associated with low sper...
Sperm phosphoproteomics: historical perspectives and current methodologies
2012
Mammalian sperm are differentiated germ cells that transfer genetic material from the male to the female. Owing to this essential role in the reproductive process, an understanding of the complex mechanisms that underlie sperm function has implications ranging from the development of novel contraceptives to the treatment of male infertility. While the importance of phosphorylation in sperm differentiation, maturation and fertilization has been well established, the ability to directly determine the sites of phosphorylation within sperm proteins and to quantitate the extent of phosphorylation at these sites is a recent development that has relied almost exclusively on advances in the field of proteomics. This review will summarize the work that has been carried out to date on sperm phosphoproteomics and discuss how the resulting qualitative and quantitative information has been used to provide insight into the manner in which protein phosphorylation events modulate sperm function. The authors also present the proteomics process as it is most often utilized for the elucidation of protein expression, with a particular emphasis on the way in which the process has been modified for the analysis of protein phosphorylation in sperm.
Alterations in sperm protein phosphorylation in male infertility
Andrologia, 2009
Protein phosphorylation is involved in sperm capacitation, so the effect of protein phosphatase inhibitors on the capacitation of spermatozoa of males with unexplained infertility was investigated. D-mannose ligand speci®c receptor expression in fresh, living spermatozoa, capacitated or treated with calyculin A (an inhibitor of protein phosphatases 1 and 2A), was studied in three groups of men: pre-vasectomy (fertile) males, males in couples with male infertility, and males in couples with infertility of unknown aetiology. Flow cytometry showed sig-ni®cant differences between infertile couples with a male factor and fertile couples (P<0.05), both after capacitation and after treatment with calyculin A. In the group of couples with infertility of unknown aetiology (n=15), D-mannose receptor expression was diminished in six cases after classical capacitation. However, when the spermatozoa of these six men were treated with calyculin A, ®ve showed an increased speci®c D-mannose receptor expression. From these results it is suggested that in vitro treatment of spermatozoa with inhibitors of protein phosphatases may be of great value in some cases of unexplained infertility.
“OMICS” of Human Sperm: Profiling Protein Phosphatases
OMICS: A Journal of Integrative Biology, 2013
Phosphorylation is a major regulatory mechanism in eukaryotic cells performed by the concerted actions of kinases and phosphatases (PPs). Protein phosphorylation has long been relevant to sperm physiology, from acquisition of motility in the epididymis to capacitation in the female reproductive tract. While the precise kinases involved in the regulation of sperm phosphorylation have been studied for decades, the PPs have only recently received research interest. Tyrosine phosphorylation was first implicated in the regulation of several sperm-related functions, from capacitation to oocyte binding. Only afterwards, in 1996, the inhibition of the serine/threonine-PP phosphoprotein phosphatase 1 (PPP1) by okadaic acid and calyculin-A was shown to initiate motility in caput epididymal sperm. Today, the current mechanisms of sperm motility acquisition based on PPP1 and its regulators are still far from being fully understood. PPP1CC2, specifically expressed in mammalian sperm, has been considered to be the only sperm-specific serine/threonine-PP, while other PPP1 isoforms were thought to be absent from sperm. This article examines the ''Omics'' of human sperm, and reports, for the first time, the identification of three new serine/threonine-protein PPs, PPP1CB, PPP4C, and PPP6C, in human sperm, together with two tyrosine-PPs, MKP1 and PTP1C. We specifically localized in sperm PPP1CB and PPP1CC2 from the PPP1 subfamily, and PPP2CA, PPP4C, and PPP6C from the PPP2 subfamily of the serine/threonine-PPs. A semi-quantitative analysis was performed to determine the various PPs' differential expression in sperm head and tail. These findings contribute to a comprehensive understanding of human sperm PPs, and warrant further research for their clinical and therapeutic significance.
Journal of Proteomics, 2020
Human sperm motility is essential for fertilization and among pathologies underlying male infertility is asthenozoospermia. Nevertheless, mechanisms regulating sperm motility are not completely unraveled. This work investigates phosphoproteins underlying human sperm motility by using differential phosphoproteomic in two human sperm subpopulations: high (HM) and low (LM) motility, obtained by centrifugation in a density gradient. Phosphoproteomics (HPLC-MS/MS triple TOF), comparing human LM and HM phosphoproteomes, identified 210 phosphopeptides with different abundance that correspond with 119 sperm proteins. Analysis showed that 40% of phosphoproteins in LM spermatozoa are involved in metabolism, (catabolism, protein transport, lipid biosynthesis), 25% in spermatogenesis and sperm function, 8% in immune system and 6% in DNA repair. In HM spermatozoa, 48% of phosphoproteins are related to spermatogenesis and sperm function (motility), whereas 8% are associated to metabolism. GSK3α resulted one of the most abundant phosphoproteins in HM spermatozoa. Western blot confirmed that GSK3α phosphorylation is higher in HM spermatozoa. Summarizing, this study i) identified phosphoproteins in two human spermatozoa populations, ii) supports that human spermatozoa rely in protein phosphorylation, such as GSK3 α, to regulate sperm motility, iv) raises the challenge of using some identified human sperm phosphorylated proteins (GSK3α) as targets to develop into clinically relevant biomarkers. Significance: Human sperm phosphoproteome analyzed by nano HPLC-MS/MS triple TOF identifies the differential abundance of sperm phosphoproteins in two human sperm populations exhibiting high motility (HM) and/ or low motility (LM) that were isolated from normozoospermic healthy donors. Majority of human phosphoproteins found in LM spermatozoa are involved in sperm metabolism (40%), whereas those in HM spermatozoa are associated to spermatogenesis and sperm function, as motility (48%), and only 8% are associated to metabolism. One of the most abundant phosphoproteins found in HM spermatozoa is GSK3α, kinase directly involved in the regulation of sperm motility that was also validated by western blot. The biological relevance of this study is based in the fact that supports that mature human sperm cells rely in protein phosphorylation to efficiently regulate sperm motility and allows identifying those regulatory human sperm phosphoproteins. This work will clearly impacts the human reproductive field as it raises the challenge of consider identified human sperm phosphoproteins, such as GSK3α, as potential biological targets to develop into relevant biomarkers for the human clinic or assisted reproductive technology.
Human Reproduction, 2004
BACKGROUND: Human semen is composed of a heterogeneous population of sperm with varying degrees of structural and functional differentiation and normality, which result in subpopulations of different quality. METHODS: Using a discontinuous Percoll gradient, we separated three subsets of sperm [(45%; L45), (65%; L65) and (90%; L90) fractions] from normozoospermic human semen samples from healthy donors and proceeded to characterize their morphology, motility and hyperactivation, as well as their ability to undergo tyrosine phosphorylation under capacitating conditions. RESULTS: As expected, sperm isolated from the lowest density layer (L45) showed the poorest quality, displaying the smallest percentage of morphologically normal and motile sperm. During a capacitating incubation, this subset of cells also showed de®cient capacity to undergo hyperactivation and protein tyrosine phosphorylation. Conversely, sperm isolated from the other layers (L65 and L90) showed a time-dependent progressive increment in tyrosine phosphorylation, establishing statistically signi®cant differences with sperm from L45. The tyrosine phosphorylation de®ciency of L45 sperm could be overcome when sperm from that fraction were stimulated with activators of the cAMP-dependent kinase (PKA) pathway (dbcAMP + pentoxifylline), pointing to the sperm's plasma membrane as the main site of such de®ciency. CONCLUSIONS: Poor quality sperm isolated from a Percoll gradient display an intrinsic tyrosine phosphorylation de®ciency, possibly caused by a plasma membrane defect, which is associated with their inability to undergo normal capacitation and, ultimately, acquire optimal fertilizing potential.
Protein phosphorylation in mammalian spermatozoa
Reproduction, 2003
Spermatozoa undergo a series of changes before and during egg binding to acquire the ability to fuse with the oocyte. These priming events are regulated by the activation of compartmentalized intracellular signalling pathways, which control the phosphorylation status of sperm proteins. Increased protein tyrosine phosphorylation is associated with capacitation, hyperactivated motility, zona pellucida binding, acrosome reaction and sperm-oocyte binding and fusion. The main tyrosine phosphorylated proteins during the course of capacitation and fertilization are localized to the flagellum, although tyrosine phosphorylation of less abundant proteins may also be regulated in the sperm head. Spermatozoa bound to the zona pellucida and fusing with the oocyte plasma membrane are characterized by a tyrosine phosphorylated flagellum. Protein phosphorylation in the flagellum is linked to hyperactivated motility in spermatozoa, but may also regulate additional functions involved in sperm-oocyte ...
Mammalian Sperm Fertility Related Proteins
International Journal of Medical Sciences, 2000
Infertility is an important aspect of human and animal reproduction and still presents with much etiological ambiguity. As fifty percent of infertility is related to the male partner, molecular investigations on sperm and seminal plasma can lead to new knowledge on male infertility. Several comparisons between fertile and infertile human and other species sperm proteome have shown the existence of potential fertility markers. These proteins have been categorized into energy related, structural and other functional proteins which play a major role in sperm motility, capacitation and sperm-oocyte binding. The data from these studies show the impact of sperm proteome studies on identifying different valuable markers for fertility screening. In this article, we review recent development in unraveling sperm fertility related proteins.
Male infertility refers to the inability of a man to achieve a pregnancy in a fertile female. In more than one-third of cases, infertility arises due to the male factor. Therefore, developing strategies for the diagnosis and prognosis of male infertility is critical. Simultaneously, a satisfactory model for the cellular mechanisms that regulate normal sperm function must be established. In this regard, tyrosine phosphorylation is one of the most common mechanisms through which several signal transduction pathways are adjusted in spermatozoa. It regulates the various aspects of sperm function, for example, motility, hyperactivation, capacitation, the acrosome reaction, fertilization, and beyond. Several recent large-scale studies have identified the proteins that are phosphorylated in spermatozoa to acquire fertilization competence. However, most of these studies are basal and have not presented an overall mechanism through which tyrosine phosphorylation regulates male infertility. In this review, we focus of this mechanism, discussing most of the tyrosine-phosphorylated proteins in spermatozoa that have been identified to date. We categorized tyrosine-phosphorylated proteins in spermatozoa that regulate male infertility using MedScan Reader (v5.0) and Pathway Studio (v9.0).