Regulation of hyperactivation by PPP2 in hamster spermatozoa

Suzuki, Tatsuya; Fujinoki, Masakatsu; Shibahara, Hiroaki; Suzuki, Mitsuaki

doi:10.1530/rep-08-0366

Cited by 28 publications

(22 citation statements)

References 47 publications

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“…It has been reported that PP1γ is inhibited through phosphorylation on Thr (Thr320) and that PP2A is inhibited through phosphorylation on Tyr (Tyr307). This effect has been observed in sperm of mouse [14], pig [52], and hamster [61]. These results are consistent with our observations that the enzymatic activities of PP1, PP2B, and PP2A are low during capacitation.…”

Section: Discussionsupporting

confidence: 93%

Protein Phosphatases Decrease Their Activity during Capacitation: A New Requirement for This Event

et al. 2013

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There are few reports on the role of protein phosphatases during capacitation. Here, we report on the role of PP2B, PP1, and PP2A during human sperm capacitation. Motile sperm were resuspended in non-capacitating medium (NCM, Tyrode's medium, albumin- and bicarbonate-free) or in reconstituted medium (RCM, NCM plus 2.6% albumin/25 mM bicarbonate). The presence of the phosphatases was evaluated by western blotting and the subcellular localization by indirect immunofluorescence. The function of these phosphatases was analyzed by incubating the sperm with specific inhibitors: okadaic acid, I2, endothall, and deltamethrin. Different aliquots were incubated in the following media: 1) NCM; 2) NCM plus inhibitors; 3) RCM; and 4) RCM plus inhibitors. The percent capacitated sperm and phosphatase activities were evaluated using the chlortetracycline assay and a phosphatase assay kit, respectively. The results confirm the presence of PP2B and PP1 in human sperm. We also report the presence of PP2A, specifically, the catalytic subunit and the regulatory subunits PR65 and B. PP2B and PP2A were present in the tail, neck, and postacrosomal region, and PP1 was present in the postacrosomal region, neck, middle, and principal piece of human sperm. Treatment with phosphatase inhibitors rapidly (≤1 min) increased the percent of sperm depicting the pattern B, reaching a maximum of ∼40% that was maintained throughout incubation; after 3 h, the percent of capacitated sperm was similar to that of the control. The enzymatic activity of the phosphatases decreased during capacitation without changes in their expression. The pattern of phosphorylation on threonine residues showed a sharp increase upon treatment with the inhibitors. In conclusion, human sperm express PP1, PP2B, and PP2A, and the activity of these phosphatases decreases during capacitation. This decline in phosphatase activities and the subsequent increase in threonine phosphorylation may be an important requirement for the success of sperm capacitation.

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Section: Discussionsupporting

confidence: 93%

Protein Phosphatases Decrease Their Activity during Capacitation: A New Requirement for This Event

et al. 2013

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“…ERKs, also known a specific subset of the MAPK family, are a class of serine/threonine kinases which phosphorylate several types of proteins. The upstream cascade of the ERK pathway consists of the adaptorproteins of SHC, GRB2 and SOS and the GTP-binding proteins of the RAS or RHO families [20–21]. The ERK pathway is initiated extracellularly by ligands and intracellularly by reactive oxygen species.…”

Section: Different Pathways In Capacitationmentioning

confidence: 99%

“…Specifically, a particular type of sAC by acting as intracellular signal [13, 17–18], has been shown to induce tyrosine phosphorylation in stallion sperm [19]. sAC also activated specific protein kinases and phosphates [20–21]. …”

Section: Introductionmentioning

confidence: 99%

Factors and pathways involved in capacitation: how are they regulated?

Jin

Yang

2016

Oncotarget

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In mammals, fertilization occurs via a comprehensive progression of events. Freshly ejaculated sperm have yet to acquire progressive motility or fertilization ability. They must first undergo a series of biochemical and physiological changes, collectively known as capacitation. Capacitation is a significant prerequisite to fertilization. During the process of capacitation, changes in membrane properties, intracellular ion concentration and the activities of enzymes, together with other protein modifications, induce multiple signaling events and pathways in defined media in vitro or in the female reproductive tract in vivo. These, in turn, stimulate the acrosome reaction and prepare spermatozoa for penetration of the egg zona pellucida prior to fertilization. In the present review, we conclude all mainstream factors and pathways regulate capacitation and highlight their crosstalk. We also summarize the relationship between capacitation and assisted reproductive technology or human disease. In the end, we sum up the open questions and future avenues in this field.

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“…For protein phosphorylations, it has been suggested that tyrosine phosphorylations are closely associated with capacitation (Visconti et al 1995, Fujinoki et al 2001b, 2006, Jha & Shivaji 2001. Moreover, 80 and/or 85 kDa tyrosine phosphorylations are regulated by calcium/ calmodulin-dependent signals (Carrera et al 1996) and protein phosphatase 1 (Suzuki et al 2010), and are identified as A-kinase anchoring protein (AKAP; Carrera et al 1996, Jha & Shivaji 2002.…”

Section: Introductionmentioning

confidence: 99%

Suppression of progesterone-enhanced hyperactivation in hamster spermatozoa by estrogen

Fujinoki¹

2010

Reproduction

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In this study, I examined whether sperm hyperactivation in hamster is regulated by steroid hormones such as estrogen (estradiol, E 2 ) and progesterone. Although sperm hyperactivation was enhanced by progesterone, 17b-estradiol (17bE 2 ) itself did not affect sperm hyperactivation. However, 17bE 2 suppressed progesterone-enhanced hyperactivation in a concentration-dependent manner through non-genomic pathways when spermatozoa were exposed to 17bE 2 at the same time or before exposure to progesterone. When spermatozoa were exposed to 17bE 2 after exposure to progesterone, 17bE 2 did not suppress progesterone-enhanced hyperactivation. Moreover, 17a-estradiol, an inactive isomer of E 2 , did not suppress progesterone-enhanced hyperactivation. Observations using a FITC-conjugated 17bE 2 showed that it binds to the acrosome region of the sperm head. Binding of 17bE 2 to spermatozoa was not inhibited by progesterone, although 17bE 2 did not suppress progesterone-enhanced hyperactivation when spermatozoa were exposed to 17bE 2 after exposure to progesterone. On the other hand, binding of progesterone to spermatozoa was also not inhibited by 17bE 2 even if progesterone-enhanced hyperactivation was suppressed by 17bE 2 . Although tyrosine phosphorylations of sperm proteins were enhanced by progesterone, enhancement of tyrosine phosphorylations by progesterone was suppressed by 17bE 2 . Moreover, tyrosine phosphorylations were inhibited by 17bE 2 when only 17bE 2 was added to the medium. From these results, it is likely that 17bE 2 competitively suppresses progesterone-enhanced hyperactivation through the inhibition of tyrosine phosphorylations via non-genomic pathways.

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Regulation of hyperactivation by PPP2 in hamster spermatozoa

Cited by 28 publications

References 47 publications

Protein Phosphatases Decrease Their Activity during Capacitation: A New Requirement for This Event

Protein Phosphatases Decrease Their Activity during Capacitation: A New Requirement for This Event

Factors and pathways involved in capacitation: how are they regulated?

Suppression of progesterone-enhanced hyperactivation in hamster spermatozoa by estrogen

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