MicroRNA-17 post-transcriptionally regulates polycystic kidney disease-2 gene and promotes cell proliferation.

To identify the possible microRNAs (miRNAs) which target the polycystic kidney disease-2 gene (PKD2), and clarify effects of the miRNAs on PKD2. We preliminarily used bioinformatics to analyze 3'UTR (3'untranslated regions) of PKD1 and PKD2 in order to predict the potential microRNAs targeted on them. Subsequently, the stable cell lines with overexpression of microRNA-17 (miR-17) were screened, and luciferase assay combined with the mutation 3'UTR of PKD2 were performed to verify PKD2 is the target of miR-17. Moreover, RT-PCR and Western Blotting were used to determine the post-transcriptionally regulation of PKD2 by miR-17. Finally, MTT cell assays allied with PKD2 rescued strategy were employed to evaluate cell proliferation effects. Our study firstly found that the 3'UTR of PKD2 was more conservation than that of PKD1, and microRNA-17 directly targets the 3'UTR of PKD2 and post-transcriptionally repress the expression of PKD2. Moreover, our findings also demonstrated that overexpression of miR-17 may promote cell proliferation via post-transcriptionally repression of PKD2 in HEK 293T. This suggested that microRNA might be a novel mechanism for cystogenesis as well as a potential therapeutic target for the cell proliferation of autosomal dominant polycystic kidney disease (ADPKD).

TC1 (C8orf4) is involved in ERK1/2 pathway-regulated G(1)- to S-phase transition.

Although previous studies have implicated a role for TC1 (C8orf4) in cancer cell proliferation, the molecular mechanism of its action is still largely unclear. In this study, we showed, for the first time, that the mRNA levels of TC1 were upregulated by mitogens (FBS/thrombin) and at least partially, through the ERK1/2 signaling pathway. Interestingly, the over-expression of TC1 promoted the G(1)- to S-phase transition of the cell cycle, which was delayed by the deficiency of ERK1/2 signaling in fibroblast cells. Furthermore, the luciferase reporter assay indicated that the over-expression of TC1 significantly increased Cyclin D1 promoter-driven luciferase activity. Taken together, our findings revealed that TC1 was involved in the mitogen-activated ERK1/2 signaling pathway and positively regulated G(1)- to S-phase transition of the cell cycle. Our results may provide a novel mechanism of the role of TC1 in the regulation of cell proliferation.

Expression of Pkd2l2 in testis is implicated in spermatogenesis.

Pkd2l2 is a novel member of the polycystic kidney disease (PKD) gene family in mammals. Prominently expressed in testis, this gene is still poorly understood. In this study, reverse transcription polymerase chain reaction (RT-PCR) results showed a time-dependent expression pattern of Pkd2l2 in postnatal mouse testis. Immunohistochemical analysis revealed that Pkd2l2 encoded a protein, polycystin-L2, which was predominantly detectable in the plasma membrane of spermatocytes and round spermatids, as well as in the head and tail of elongating spermatids within seminiferous tubules in mouse testis tissue sections of postnatal day 14 and adult mice. A green fluorescent fusion protein of Pkd2l2 resided in the plasma membrane of HEK 293 and MDCK cells, suggesting that it functions as a plasma membrane protein. Overexpression of Pkd2l2 increased the intracellular calcium concentration of MDCK cells, as detected by flow cytometry. Collectively, these data indicated that Pkd2l2 may be involved in the mid-late stage of spermatogenesis through modulation of the intracellular calcium concentration.