人類KIAA0020蛋白為pumilio蛋白家族的一員，而pumilio家族隸屬於RNA結合蛋白。目前對於pumilio家族蛋白的研究指出，此種蛋白的功能為結合上RNA的三端非轉譯區域片段，藉此調控mRNA在轉譯的穩定性。KIAA0020在不同癌症組織的表現量有不同的表現，並且現階段對於KIAA0020蛋白在轉譯的功能上還沒有被了解。本研究利用免疫細胞化學染色發現KIAA0020蛋白在人類HeLa及HEK293T細胞中，發現KIAA0020座落於細胞核內並有聚集現象，並且也利用去除KIAA0020 N端或C端的變異蛋白在 HEK293T細胞中表現的位置，推論N端或C端對於此蛋白聚集於核內及入核的現象為重要的區域。另外，本研究也利用半定量聚合酶鏈式反應，測量候選基因mRNA的表現量，及西方點漬法測量後選基因DDX3x蛋白，在這些研究結果發現KIAA0020與調控DDX3x有相當的關係，也在RNA免疫沉澱分析中也發現DDX3x mRNA能與KIAA0020蛋白有結合的現象。本研究也利用標定35S至新合成蛋白的分析下發現，人類神經母細胞瘤NB69細胞在穩定表現KIAA0020蛋白的情況下有較多新合成的蛋白。這些結果暗示了KIAA0020蛋白在細胞中的角色可能有參與轉錄到轉譯的過程，但還須更多方面的探討來確定KIAA0020蛋白在細胞中的功能。

Human KIAA0020 belongs to the Puf-family, a protein family of RNA-binding proteins. The functions of the Puf-family members in some species are known to bind to the 3’UTR and hence modulate the stability of mRNA during translation. Although the role of human KIAA0020 in translation is currently unclear, it is frequently deregulated in a variety of cancers. We found in immunocytochemistry experiment that KIAA0020 is localized to and aggregate in the nuclei of human HeLa and HEK293T cells. And by overexpressing N and/or C terminal deleted KIAA0020 in HEK293T cell, both N- and C-terminal appeared to be essential for its nuclear localization and staining patterns. Furthermore, the results of semi-quantitative RT-PCR and western blot showed that the expression level of the candidate mRNA DDX3x may be regulated by KIAA0020. In RNA immunoprecipitation assay we also demonstrated that DDX3x mRNA interact with KIAA0020 proteins. In this study, 35S labeling assay is also used to demonstrate that KIAA0020 overexpression in human neuroblastoma NB69 cells increase global translation level of the cell. These studies provide preliminary understanding about the functions of KIAA0020 in cellular function; however, further investigation is required to clarify the role of KIAA0020 protein in cells.

1. Wickens M, Bernstein DS, Kimble J, Parker R (2002) A PUF family portrait: 3'UTR regulation as a way of life. Trends Genet 18: 150-157.
2. Chritton JJ, Wickens M (2010) Translational repression by PUF proteins in vitro. RNA 16: 1217-1225.
3. Lu G, Dolgner SJ, Hall TM (2009) Understanding and engineering RNA sequence specificity of PUF proteins. Curr Opin Struct Biol 19: 110-115.
4. Wang Y, Opperman L, Wickens M, Hall TM (2009) Structural basis for specific recognition of multiple mRNA targets by a PUF regulatory protein. Proc Natl Acad Sci U S A 106: 20186-20191.
5. Saint-Georges Y, Garcia M, Delaveau T, Jourdren L, Le Crom S, et al. (2008) Yeast mitochondrial biogenesis: a role for the PUF RNA-binding protein Puf3p in mRNA localization. PLoS One 3: e2293.
6. Miller MT, Higgin JJ, Hall TM (2008) Basis of altered RNA-binding specificity by PUF proteins revealed by crystal structures of yeast Puf4p. Nat Struct Mol Biol 15: 397-402.
7. Galgano A, Forrer M, Jaskiewicz L, Kanitz A, Zavolan M, et al. (2008) Comparative analysis of mRNA targets for human PUF-family proteins suggests extensive interaction with the miRNA regulatory system. PLoS One 3: e3164.
8. Gerber AP, Herschlag D, Brown PO (2004) Extensive association of functionally and cytotopically related mRNAs with Puf family RNA-binding proteins in yeast. PLoS Biol 2: E79.
9. Zhang B, Gallegos M, Puoti A, Durkin E, Fields S, et al. (1997) A conserved RNA-binding protein that regulates sexual fates in the C. elegans hermaphrodite germ line. Nature 390: 477-484.
10. Murata Y, Wharton RP (1995) Binding of pumilio to maternal hunchback mRNA is required for posterior patterning in Drosophila embryos. Cell 80: 747-756.
11. Kaye JA, Rose NC, Goldsworthy B, Goga A, L'Etoile ND (2009) A 3'UTR pumilio-binding element directs translational activation in olfactory sensory neurons. Neuron 61: 57-70.
12. Gu W, Deng Y, Zenklusen D, Singer RH (2004) A new yeast PUF family protein, Puf6p, represses ASH1 mRNA translation and is required for its localization. Genes Dev 18: 1452-1465.
13. Tadauchi T, Matsumoto K, Herskowitz I, Irie K (2001) Post-transcriptional regulation through the HO 3'-UTR by Mpt5, a yeast homolog of Pumilio and FBF. EMBO J 20: 552-561.
14. Vessey JP, Schoderboeck L, Gingl E, Luzi E, Riefler J, et al. (2010) Mammalian Pumilio 2 regulates dendrite morphogenesis and synaptic function. Proc Natl Acad Sci U S A 107: 3222-3227.
15. Kuo MW, Wang SH, Chang JC, Chang CH, Huang LJ, et al. (2009) A novel puf-A gene predicted from evolutionary analysis is involved in the development of eyes and primordial germ-cells. PLoS One 4: e4980.
16. Gupta YK, Nair DT, Wharton RP, Aggarwal AK (2008) Structures of human Pumilio with noncognate RNAs reveal molecular mechanisms for binding promiscuity. Structure 16: 549-557.
17. Cheong CG, Hall TM (2006) Engineering RNA sequence specificity of Pumilio repeats. Proc Natl Acad Sci U S A 103: 13635-13639.
18. Brickner AG, Warren EH, Caldwell JA, Akatsuka Y, Golovina TN, et al. (2001) The immunogenicity of a new human minor histocompatibility antigen results from differential antigen processing. J Exp Med 193: 195-206.
19. Abdelhaleem M, Maltais L, Wain H (2003) The human DDX and DHX gene families of putative RNA helicases. Genomics 81: 618-622.
20. Lee CS, Dias AP, Jedrychowski M, Patel AH, Hsu JL, et al. (2008) Human DDX3 functions in translation and interacts with the translation initiation factor eIF3. Nucleic Acids Res 36: 4708-4718.
21. Schroder M (2010) Human DEAD-box protein 3 has multiple functions in gene regulation and cell cycle control and is a prime target for viral manipulation. Biochem Pharmacol 79: 297-306.
22. Chao CH, Chen CM, Cheng PL, Shih JW, Tsou AP, et al. (2006) DDX3, a DEAD box RNA helicase with tumor growth-suppressive property and transcriptional regulation activity of the p21waf1/cip1 promoter, is a candidate tumor suppressor. Cancer Res 66: 6579-6588.