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Gene & Protein in Disease MPDZ regulates sperm motility

instructions. Primers for the amplification of the MPDZ, We found that the percentage of spermatozoa with PR visibly
Stat3, CatSper1-4, and GAPDH genes are listed in Table S1. reduced in MPDZ-null males (Figure 1F). The average
All qRT-PCR experiments were performed using sperm speed (VAP) also decreased in MPDZ-null sperm
Master mixes qRT–PCR (RR820A, Takara) with a C1000 (Figure 1G). A decline in the proportion of spermatozoa with
real-time cycler (Bio-Rad Laboratories, Hercules, CA, non-progressive motility (NP) was detected in MPDZ-null
USA). All experiments were carried out in triplicate, and ones though there was no statistical difference (Figure 1H).
the 2 -ΔΔct method was used to determine the expression of Taken together, these results showed that decreased sperm
interest genes. motility was responsible for the reduction in fertility of
MPDZ-null male mice.
Human MPDZ expression in spermatozoa was
determined by the Ct value of MPDZ divided by GAPDH 3.2. The beneficial effect of MPDZ expression on
(Ct M/G ). The cDNA of each semen sample of volunteers was human sperm motility
obtained from Li Yin (Institute of Toxicology, College of To further explore the roles of MPDZ in sperm motility, we
Preventive Medicine, Army Medical University). analyzed the association between MPDZ expression and
2.11. Statistical analysis human sperm motility. Sperm samples were divided into
two groups: one with sperm motility less than the cut-off
Data were analyzed using SPSS 20.0 for Windows (SPSS value (40%, according to WHO Laboratory Manual for the
Inc., Chicago, IL, USA) and R language. The correlation Examination and Processing of Human Semen, the fourth
between MPDZ expression and sperm motility was assayed edition ); the other with sperm motility equal and/or higher
[33]
using binary logistic regression. The correlations between than the cut-off value. As shown in Table 1, MPDZ expression
MPDZ expression and semen parameters, including sperm positively affected sperm motility with an OR = 1.601
motility, [Ca ] , progressive motility, and fast-forward (>1), although without statistical significance. Moreover, a
2+
i
progressive motility, were assessed using R language. positive association between MPDZ expression and sperm
All statistical tests were two-tailed, and a p < 0.05 was parameters was found in human sperms. MPDZ expression
considered statistically significant. was inclinedly beneficial for high levels of Ca signal, sperm
2+
3. Results motility, sperm PR, and sperm rapid PR, but contrary to
sperm with low-PR, NP, and immotility (Figure S2). These
3.1. Lack of MPDZ led to a decline in sperm motility results suggested that MPDZ expression was beneficial for
and male fertility in mice sperm motility and a high level of Ca signal in sperm.
2+
To explore the role of MPDZ in spermatozoa, MPDZ-null 3.3. MPDZ regulated Ca signal in mouse sperm
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C57BL/6 mice were used in this study . Almost all MPDZ-
[29]
null mice showed no gross abnormalities in appearance or We found that MPDZ was responsible for the regulation of
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behavior. During breeding, we found the number of litters the cell Ca signal using the String database (Figure 2A).
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sired by MPDZ-null (K/K) males were smaller than their wild- MPDZ was functionally relevant with Ca channel activity,
type (W/W) or MPDZ-heterozygous (W/K) counterparts store-operated calcium channel activity, and inositol
2+
(Figure 1A), suggesting that MPDZ-null genotype resulted 1,4,5-trisphosphate. In mouse sperm, the Ca signal was
in male fertility decline. To explore this phenomenon, we intensively uncovered in the areas of the head, neck region,
comparatively analyzed the pathological morphology of the and midpiece of the flagellum and weakly in the front of
ovaries and testes and the testis-weight ratio between the the principal piece of the flagellum (Figure 2B), which was
2+
three genotypes of mice. However, no significant differences analogous to the fact that the Ca signal was determined
among the three genotypes were observed (Figure S1A-C). in the head, neck region, midpiece of human sperm
[16]
2+
With the CASA analysis, we found that MPDZ-null mutation flagellum . The Ca signal was much lower in MPDZ-
led to a reduction in sperm motility (Figure 1) but not in null spermatozoa than in the W/W or W/K counterparts
spermatogenesis or total sperm count (Figure S1B and S1D). (Figure 2C). Meanwhile, in vitro, the Ca signal increased
2+
Compared to their W/W counterparts, the fractions of when MPDZ was overexpressed in GC2 cells (Figure 2D).
sperm with fast and medium motility in MPDZ-null mice These results indicated that MPDZ was involved in the
2+
were reduced (Figure 1B and C), accompanied by no obvious regulation of the Ca signal in mouse sperm.
change in the fraction of slow motility sperm (Figure 1D); 3.4. MPDZ regulated the expression of CatSper
meanwhile, the fraction of immotile sperm increased
(Figure 1E), indicating that MPDZ was responsible for family genes in mice
maintaining sperm motility. Progressive motility (PR) is The CatSper channel is a unique sperm cation channel,
essential for spermatozoon movement to eggs for fertilization. which is the most important ion channel for male

Volume 2 Issue 2 (2023) 4 https://doi.org/10.36922/gpd.397