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ABSTRACT: Aim: The increase in the concentration of cytosolic-free calcium ([Ca2+]i) induced by follicular fluid or progesterone has been reported to promote an acrosome reaction and alternation in several motion parameters in human sperm (hyperactivation). We previously reported that populations of sperm in cell suspension obtained from infertile men with abnormal morphology exhibited lower mean peak progesterone-evoked [Ca2+]i compared with morphologically normal sperm using cell-suspension methods. In the present study, the change in [Ca2+]i in individual normally and abnormally shaped spermatozoa was compared.Methods: The change in [Ca2+]i induced by human follicular fluid in individual spermatozoa with normal and abnormal morphology was compared using the fluorescent calcium-sensitive dye fluo-3/AM. The spatial distribution of the increase in [Ca2+]i in single sperm was also investigated.Results: The [Ca2+]i of normally shaped spermatozoa increased rapidly after the administration of human follicular fluid. The response reached a peak within 2–3 s and then slowly declined to a plateau phase. The baseline and peak fluorescence in spermatozoa with abnormal morphology was lower when compared with normal spermatozoa. The follicular-fluid-induced increase in [Ca2+]i (expressed as a percentage increase in [Ca2+]i over basal) in morphologically abnormal sperm was 39.2 ± 5.3% (n = 107, mean ± standard error), which was smaller than that of morphologically normal sperm (61.6 ± 5.7%, n = 100, P < 0.005) from seven healthy donors. The follicular-fluid-induced [Ca2+]i increases observed in sperm with morphologically abnormal mid-pieces (20.9 ± 4.3%, n = 12, P < 0.05) or tails (40.7 ± 6.0%, n = 92, P < 0.05) were lower than those of morphologically normal spermatozoa (61.6 ± 5.3%, n = 101). The follicular-fluid-induced [Ca2+]i increase of morphologically normal spermatozoa from infertile couples (35.1 ± 6.3%, n = 25, P < 0.05) was also found to be lower than that of morphologically normal spermatozoa from healthy donors.Conclusion: The present study shows that spermatozoa with abnormal morphology in healthy donors have disorders of signal transduction, as do normally shaped sperm in men from infertile couples. (Reprod Med Biol 2008; 7: 143–149)
Reproductive Medicine and Biology 08/2008; 7(3):143 - 149.
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Aira Wanajo,
Akane Sasaki,
Hiromi Nagasaki,
Shu Shimada,
Takeshi Otsubo,
Syuichi Owaki, Yasufumi Shimizu,
Yoshinobu Eishi,
Kazuyuki Kojima,
Yasuaki Nakajima,
Tatsuyuki Kawano,
Yasuhito Yuasa,
Yoshimitsu Akiyama
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ABSTRACT: The calcium channel voltage-dependent alpha2delta subunit consists of 4 genes, CACNA2D1 to CACNA2D4, of which CACNA2D2 and CACNA2D3 are located on 3p21.3 and 3p21.1, respectively. Here, we examined the relation between alpha2delta subunit gene alterations and gastric carcinogenesis.
The expression and methylation status of the alpha2delta subunit genes were analyzed by reverse transcription-polymerase chain reaction (RT-PCR) and methylation-specific PCR in gastric cancers (GCs). The effects of CACNA2D3 expression were examined by cell proliferation and adhesion assays, and they predicted target gene alterations.
Aberrant methylation of CACNA2D1 and CACNA2D3 mostly corresponded to their expression status in GC cell lines. CACNA2D1/3 methylation was detected in 10 (12.5%) and 24 (30%) of the 80 GC cases, respectively, but no CACNA2D2 methylation was seen in 32 cases. CACNA2D3 methylation was more frequently found in diffuse type than in intestinal type (16/38 [42.1%] vs 8/42 [19.0%]; P = .025) GCs. Among the 53 patients with advanced GCs, patients with cancers showing CACNA2D3 methylation had a significantly shorter survival time than patients without this methylation (P = .003). Exogenous CACNA2D3 expression strongly inhibited cell growth and adhesion and up-regulated p21 and p27 expression in HEK-293T and NUGC4 cells. Inverse effects were seen by CACNA2D3 small interfering RNA treatment in the CACNA2D3-positive cell lines, indicating that CACNA2D3 may have tumor suppressive functions.
Loss of CACNA2D3 expression through aberrant promoter hypermethylation may contribute to gastric carcinogenesis, and CACNA2D3 methylation is a useful prognostic marker for patients with advanced GC.
Gastroenterology 05/2008; 135(2):580-90. · 11.68 Impact Factor
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ABSTRACT: Hyperactivation and acrosome reaction are prerequisite steps for sperm to be able to fertilize an oocyte. In mammals, hyperactivation is defined as a movement pattern seen in spermatozoa at the site and time of fertilization. The objectives of the present experiments were to analyze the process of hyperactivation and to investigate its relationship with progesterone evoked intracellular calcium concentration ([Ca2+]i) increase and their implications with infertility. After capacitation the sperm from patients, when compared with donor's sperm, showed decreased percentage of hyperactivated sperm, molitily, progressive motility, and curvilinear velocity (VCL). On the other hand, the linearity (LIN) was increased. Amplitude of lateral head displacement (ALH) and [Ca2+]i increase (peak and plateau from baseline) showed good correlation in patients with infertility. These data suggest that impaired hyperactivation might be involved in the pathophysiology of infertility.
Journal of medical and dental sciences 04/2004; 51(1):99-104.
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ABSTRACT: To know the function of the Ca2+ channel containing alpha(1)2.3 (alpha1E) subunit (Ca(v)2.3 channel) in spermatozoa, we analyzed Ca2+ transients and sperm motility using a mouse strain lacking Ca(v)2.3 channel. The averaged rising rates of Ca2+ transients induced by alpha-D-mannose-bovine serum albumin in the head region of Ca(v)2.3-/- sperm were significantly lower than those of Ca(v)2.3+/+ sperm. A computer-assisted sperm motility assay revealed that straight-line velocity and linearity were greater in Ca(v)2.3-/- sperm than those in Ca(v)2.3+/+ sperm. These results suggest that the Ca(v)2.3 channel plays some roles in Ca2+ transients and the control of flagellar movement.
FEBS Letters 05/2002; 516(1-3):229-33. · 3.54 Impact Factor
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ABSTRACT: In mammalian male germ-line cells, low-voltage-activated (LVA) Ca2+ current has been identified and its electrophysiological properties have been studied. To investigate whether α12.3 (α1E) subunit of the voltage-dependent Ca2+ channel codes for the LVA current, whole-cell patch clamp and following reverse transcription-polymerase chain reaction (RT-PCR) experiments were performed in pachytene spermatocytes from Cav2.3+/+ and Cav2.3−/− mice. Whole-cell current in acutely dissociated pachytene spermatocytes from Cav2.3+/+ and Cav2.3−/− mice displayed a typical profile of LVA Ca2+ currents and kinetics with no significant differences. Single-cell RT-PCR revealed the expression of Cacna1g in the pachytene spermatocytes from Cav2.3+/+ and Cav2.3−/− mice in which LVA Ca2+ currents were actually recorded. These results suggest that the Cav2.3 channel makes no detectable contribution to the LVA Ca2+ current in the pachytene spermatocyte. Instead, Cav3 family such as Cav3.1 may be the likely candidates responsible for the LVA currents in pachytene spermatocytes.
Biochemical and Biophysical Research Communications.
