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Role of phosphatase of regenerating liver 1 (PRL1) in spermatogenesis

View Article: PubMed Central - PubMed

ABSTRACT

The PRL phosphatases are oncogenic when overexpressed but their in vivo biological function is less well understood. Previous gene deletion study revealed a role for PRL2 in spermatogenesis. We report here the first knockout mice lacking PRL1, the most related homolog of PRL2. We found that loss of PRL1 does not affect spermatogenesis and reproductive ability of male mice, likely due to functional compensation by the relatively higher expression of PRL2 in the testes. However, PRL1−/−/PRL2+/− male mice show testicular atrophy phenotype similar to PRL2−/− mice. More strikingly, deletion of one PRL1 allele in PRL2−/− male mice causes complete infertility. Mechanistically, the total level of PRL1 and PRL2 is negatively correlated with the PTEN protein level in the testis and PRL1+/−/PRL2−/− mice have the highest level of PTEN, leading to attenuated Akt activation and increased germ cell apoptosis, effectively halting spermatozoa production. These results provide the first evidence that in addition to PRL2, PRL1 is also required for spermatogenesis by downregulating PTEN and promoting Akt signaling. The ability of the PRLs to suppress PTEN expression underscores the biochemical basis for their oncogenic potential.

No MeSH data available.


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Deletion one PRL1 allele in PRL2−/− results in male infertility due to no sperm production.(A) Sexual desire was measured by plug rate. (B,C) Reproductive performance was measured by pregnancy rate (B) and little size (C). (D) The sperm number was determined by calculating the sperms from epididymis. (E) Caudal epididymis sections from 3 months old male mice were histologically examined by H&E staining. Scale bar = 50 μm. (F) Electron microscopic analysis of epididymal sperm from the indicated genotypes. The typical “9 + 2” microtubule structure indicates the transverse section of the sperm. Scale bar = 500 nm. *p < 0.05, **p < 0.01, ***p < 0.001 (Student’s t test). Data are representative of at least three independent experiments (mean and SD).
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f3: Deletion one PRL1 allele in PRL2−/− results in male infertility due to no sperm production.(A) Sexual desire was measured by plug rate. (B,C) Reproductive performance was measured by pregnancy rate (B) and little size (C). (D) The sperm number was determined by calculating the sperms from epididymis. (E) Caudal epididymis sections from 3 months old male mice were histologically examined by H&E staining. Scale bar = 50 μm. (F) Electron microscopic analysis of epididymal sperm from the indicated genotypes. The typical “9 + 2” microtubule structure indicates the transverse section of the sperm. Scale bar = 500 nm. *p < 0.05, **p < 0.01, ***p < 0.001 (Student’s t test). Data are representative of at least three independent experiments (mean and SD).

Mentions: To determine whether the reduced testis size affects male reproductivity, 3-months-old PRL1−/−/PRL2+/− and PRL1+/−/PRL2−/− male mice were mated with wild-type virgin females. These mice showed similar sexual desire as measured by the percentage of female mice plugged by the males (Fig. 3A). However, the percent pregnancy as well as the litter size from the PRL1−/−/PRL2+/− mice group were significantly lower than those of the wild-type (Fig. 3B,C). More strikingly, none of the females that were plugged by PRL1+/−/PRL2−/− male mice were pregnant, indicating that a single PRL1 allele deletion in PRL2 deficient mice results in male infertility (Fig. 3B,C). To further characterize the functionality of the testis, the number of spermatozoa from the epididymis of 3-months old male mice was counted using a hemocytometer. In agreement with previous findings21, the number of sperms from the PRL2−/− mice was only 54 ± 18% of the wild-type controls (Fig. 3D). Similarly, the PRL1−/−/PRL2+/− mice also had significantly decreased sperm counts (68 ± 9% of wild-type) (Fig. 3D), suggesting that both PRL1 and PRL2 contribute to sperm production. Not surprisingly, PRL1+/−/PRL2−/− male mice lost 93 ± 5% of sperms in the epididymis (Fig. 3D), which explained their sterility. Consistent with this observation, H&E staining on caudal epididymis, where mature spermatozoa accumulate, failed to reveal any morphologically normal spermatozoa in the epididymis of PRL1+/−/PRL2−/− mice (Fig. 3E). Although more round-shaped non-spermatozoa cells were also found in the epididymis of PRL2−/− and PRL1−/−/PRL2+/− mice, most of the cells were morphologically normal spermatozoa (Fig. 3E). To further characterize the structural defects of spermatozoa in the epididymis, we performed transmission electron microscopy (TEM) analysis. We found that sperms in PRL1 knockout mice displayed similar density and structural features as the sperms in the wild-type. In both PRL2−/− and PRL1−/−/PRL2+/− mice, some sperms were released as a cluster, indicating that these sperms failed to complete cell division. As expected, sperms were rarely observed in PRL1+/−/PRL2−/− mice, and immature spermatocytes were released into epididymis, indicating increased germ cell apoptosis (Fig. 3F). Taken together, the data suggest that, in addition to PRL2, PRL1 also controls sperm production, which directly affects male reproductive ability. Given that the total levels of PRL1/2 in the testis of PRL1−/−, PRL2−/−, PRL1−/−/PRL2+/− and PRL1+/−/PRL2−/− mice are 70%, 30%, 35% and 15% of that of the wild-type, respectively (Supplemental Table 1), the data support our hypothesis that the reduction of the combined level of PRL1 and PRL2 correlates with the severity of testicular atrophy phenotype and the impairment of reproductive ability of male mice.


Role of phosphatase of regenerating liver 1 (PRL1) in spermatogenesis
Deletion one PRL1 allele in PRL2−/− results in male infertility due to no sperm production.(A) Sexual desire was measured by plug rate. (B,C) Reproductive performance was measured by pregnancy rate (B) and little size (C). (D) The sperm number was determined by calculating the sperms from epididymis. (E) Caudal epididymis sections from 3 months old male mice were histologically examined by H&E staining. Scale bar = 50 μm. (F) Electron microscopic analysis of epididymal sperm from the indicated genotypes. The typical “9 + 2” microtubule structure indicates the transverse section of the sperm. Scale bar = 500 nm. *p < 0.05, **p < 0.01, ***p < 0.001 (Student’s t test). Data are representative of at least three independent experiments (mean and SD).
© Copyright Policy - open-access
Related In: Results  -  Collection

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getmorefigures.php?uid=PMC5035919&req=5

f3: Deletion one PRL1 allele in PRL2−/− results in male infertility due to no sperm production.(A) Sexual desire was measured by plug rate. (B,C) Reproductive performance was measured by pregnancy rate (B) and little size (C). (D) The sperm number was determined by calculating the sperms from epididymis. (E) Caudal epididymis sections from 3 months old male mice were histologically examined by H&E staining. Scale bar = 50 μm. (F) Electron microscopic analysis of epididymal sperm from the indicated genotypes. The typical “9 + 2” microtubule structure indicates the transverse section of the sperm. Scale bar = 500 nm. *p < 0.05, **p < 0.01, ***p < 0.001 (Student’s t test). Data are representative of at least three independent experiments (mean and SD).
Mentions: To determine whether the reduced testis size affects male reproductivity, 3-months-old PRL1−/−/PRL2+/− and PRL1+/−/PRL2−/− male mice were mated with wild-type virgin females. These mice showed similar sexual desire as measured by the percentage of female mice plugged by the males (Fig. 3A). However, the percent pregnancy as well as the litter size from the PRL1−/−/PRL2+/− mice group were significantly lower than those of the wild-type (Fig. 3B,C). More strikingly, none of the females that were plugged by PRL1+/−/PRL2−/− male mice were pregnant, indicating that a single PRL1 allele deletion in PRL2 deficient mice results in male infertility (Fig. 3B,C). To further characterize the functionality of the testis, the number of spermatozoa from the epididymis of 3-months old male mice was counted using a hemocytometer. In agreement with previous findings21, the number of sperms from the PRL2−/− mice was only 54 ± 18% of the wild-type controls (Fig. 3D). Similarly, the PRL1−/−/PRL2+/− mice also had significantly decreased sperm counts (68 ± 9% of wild-type) (Fig. 3D), suggesting that both PRL1 and PRL2 contribute to sperm production. Not surprisingly, PRL1+/−/PRL2−/− male mice lost 93 ± 5% of sperms in the epididymis (Fig. 3D), which explained their sterility. Consistent with this observation, H&E staining on caudal epididymis, where mature spermatozoa accumulate, failed to reveal any morphologically normal spermatozoa in the epididymis of PRL1+/−/PRL2−/− mice (Fig. 3E). Although more round-shaped non-spermatozoa cells were also found in the epididymis of PRL2−/− and PRL1−/−/PRL2+/− mice, most of the cells were morphologically normal spermatozoa (Fig. 3E). To further characterize the structural defects of spermatozoa in the epididymis, we performed transmission electron microscopy (TEM) analysis. We found that sperms in PRL1 knockout mice displayed similar density and structural features as the sperms in the wild-type. In both PRL2−/− and PRL1−/−/PRL2+/− mice, some sperms were released as a cluster, indicating that these sperms failed to complete cell division. As expected, sperms were rarely observed in PRL1+/−/PRL2−/− mice, and immature spermatocytes were released into epididymis, indicating increased germ cell apoptosis (Fig. 3F). Taken together, the data suggest that, in addition to PRL2, PRL1 also controls sperm production, which directly affects male reproductive ability. Given that the total levels of PRL1/2 in the testis of PRL1−/−, PRL2−/−, PRL1−/−/PRL2+/− and PRL1+/−/PRL2−/− mice are 70%, 30%, 35% and 15% of that of the wild-type, respectively (Supplemental Table 1), the data support our hypothesis that the reduction of the combined level of PRL1 and PRL2 correlates with the severity of testicular atrophy phenotype and the impairment of reproductive ability of male mice.

View Article: PubMed Central - PubMed

ABSTRACT

The PRL phosphatases are oncogenic when overexpressed but their in vivo biological function is less well understood. Previous gene deletion study revealed a role for PRL2 in spermatogenesis. We report here the first knockout mice lacking PRL1, the most related homolog of PRL2. We found that loss of PRL1 does not affect spermatogenesis and reproductive ability of male mice, likely due to functional compensation by the relatively higher expression of PRL2 in the testes. However, PRL1&minus;/&minus;/PRL2+/&minus; male mice show testicular atrophy phenotype similar to PRL2&minus;/&minus; mice. More strikingly, deletion of one PRL1 allele in PRL2&minus;/&minus; male mice causes complete infertility. Mechanistically, the total level of PRL1 and PRL2 is negatively correlated with the PTEN protein level in the testis and PRL1+/&minus;/PRL2&minus;/&minus; mice have the highest level of PTEN, leading to attenuated Akt activation and increased germ cell apoptosis, effectively halting spermatozoa production. These results provide the first evidence that in addition to PRL2, PRL1 is also required for spermatogenesis by downregulating PTEN and promoting Akt signaling. The ability of the PRLs to suppress PTEN expression underscores the biochemical basis for their oncogenic potential.

No MeSH data available.


Related in: MedlinePlus