以异源四倍体鲫鲤及其二倍体父/母本(湘江野鲤/红鲫)和子代三倍体湘云鲫等为实验材料，运用Western-blotting技术及荧光免疫组织化学技术等实验手段，分析了PP-1的催化亚基在上述不同倍性鱼体内的表达模式：蛋白水平检测发现PP-1c在不同倍性鱼的大脑、心脏、肌肉、肾脏、肝脏和性腺6种主要器官组织中均有表达，且不同的组织中显示了明显的差异表达模式，而PP-1c在这4种不同鱼的肌肉组织中的表达差异更显著，其中在异源四倍体鲫鲤中表达最低，在父/母本红鲫中的表达水平相对较高，子代三倍体湘云鲫中的表达最高,这种差异性可能从生化的角度说明了子代与父母本之间的变异性。免疫荧光组化实验结果显示，从整体水平来看，4种不同鱼的同一组织中，PP-1c的表达模式是非常相似的，这可能从蛋白和细胞的水平说明了异源四倍体鲫鲤与其二倍体父/母本及子代三倍体湘云鲫之间的遗传相似性。但对于同一组织的不同细胞的具体表达部位是有差异的，具有细胞特异性。

Protein phosphorylation and dephosphorylation are the most important regulatory mechanisms governing many aspects of biology. Phosphoproteome studies have revealed that phosphorylation and dephosphorylation modulate functions of more than one third of the total cellular proteins. In eukaryotes, dephosphorylation at serine/threonine residues are executed by four major protein phosphatases, Phosphatase-1(PP-1), Phosphatase-2A(PP-2A), Phosphatase-2B(PP-2B), Phosphatase-2C(PP-2C), and several minor phosphatases including Phosphatase-4(PP-4), Phosphatase-5(PP-5), Phosphatase-6(PP-6), and Phosphatase-7(PP-7). Among these different phosphatases, Protein Phosphatase-1(PP-1) is one of the most important protein serine/threonine and plays distinct roles in regulating gene expression, signal transduction, cell proliferation, differentiation, transmission, apoptosis, autophagy, morphogenesis, organogenesis and other cellular activities. Our previous studies have demonstrated that PP-1 is a major phosphatase that dephosphorylates Pax6 to modulate its function in regulating brain and eye development. More recently, we have established the expression patterns of the catalytic subunits and the regulatory subunits for PP-1 in mouse eye. To explore the possible functions of PP-1 in various tissues of the lower vertebrates, here, we have analyzed the differential expression patterns and the cellular localizations of the catalytic subunit for PP-1 using western blot and immunohistochemistry on four different ploidy fish: the allotetraploid hybrids and their diploid parents, common carp (♂) and red crucian carp (♀) as well as the triploid crucian carp derived from crossover between the allotetraploids and common carp or between the allotetraploids and the red crucian carp. Our study demonstrated the following results: (1) PP-1c is expressed in the brain, heart, muscle, kidney, liver, and gonads with defined differential expression patterns. (2) The most striking feature is that a relatively higher level of PP-1c expression was found in the muscle of the above fish. (3) Compared among the muscle tissues from 4 types of fish, the lowest level of PP-1c expression was detected in the allotetraploid fish, an intermediate level of PP-1c detected in both parents and the highest level of PP1c observed in the triploid crucian carp. Such a pattern illustrates its variability between filial generation and the corresponding parents. (4) The immunohistochemistry study revealed similar localization of PP-1c in certain groups of cells within the same tissue from the four different organisms. Together, these results lead to the following conclusions: (1) PP-1c is differentially expressed in various tissues of the four different ploidy level fishes; (2) PP-1c functions are highly regulated in different tissues; (3) Within the same tissue of the four types of fish, PP-1c is localized in the same types of cells; and (4) the presence of strong PP-1c immunofluorescence signal in certain nuclei of neurons in both allotetraploid and triploid brains but not in those of the diploid parents indicates that PP-1c may be used as a biochemical marker to distinguish the different types of fish. In summary, our results represent the first report on the differential expression patterns of the protein phosphatase-1c in six tissues from the different ploidy level fish, and provide valuable information for the future study of the PP-1c functions in these organisms.

教育厅优秀青年资助项目(08B048)；教育部长江学者及创新团队计划基金资助项目（IRT0445）；湖南省“芙蓉学者”特聘教授基金资助项目（24030604）