title: A R/K-rich motif in the C-terminal of the homeodomain is required for complete translocating of NKX2.5 protein into nucleus.
abstract: NKX2.5 plays important roles in heart development. Being a transcription factor, NKX2.5 exerts its biological functions in nucleus. However, the sequence motif that localize NKX2.5 into nucleus is still not clear. Here, we found a R/K-rich sequence motif from Q187 to R197 (QNRRYKCKRQR) was required for exclusive nuclear localization of NKX2.5. Eight truncated plasmids (E109X, Q149X, Q170X, Q187X, Q198X, Y256X, Y259X, and C264X) which were associated with congenital heart disease (CHD) were constructed. Compared with the wild type NKX2.5, the proteins E109X, Q149X, Q170X, Q187X without intact homeodomain (HD) showed no transcriptional activity while Q198X, Y256X, Y259X and C264X with intact HD showed 50 to 66% transcriptional activity. E109X, Q149X, Q170X, Q187X without intact HD localized in the cytoplasm and nucleus simultaneously and Q198X, Y256X, Y259X and C264X with intact HD localized completely in nucleus. These results inferred the indispensability of 187QNRRYKCKRQR197 in exclusive nucleus localization. Additionally, this sequence motif was very conservative among human, mouse and rat, indicating this motif was important for NKX2.5 function. Thus, we concluded that R/K-rich sequence motif 187QNRRYKCKRQR197 played a central role for NKX2.5 nuclear localization. Our findings provided a clue to understand the mechanisms between the truncated NKX2.5 mutants and CHD.
authors.affiliation: Guangdong Provincial Key Laboratory of Medical Molecular Diagnostics, Dongguan Scientific Research Center, Guangdong Medical University, Dongguan, Guangdong 523808, China.
authors.forename: Ping
authors.initials: P
authors.lastname: Ouyang
authors.affiliation: Department of Occupational and Environmental Health, School of Public Health, Guangdong Medical University, Dongguan, Guangdong 523808, China.
authors.forename: He
authors.initials: H
authors.lastname: Zhang
authors.affiliation: Guangdong Provincial Key Laboratory of Medical Molecular Diagnostics, Dongguan Scientific Research Center, Guangdong Medical University, Dongguan, Guangdong 523808, China.
authors.forename: Zhaolan
authors.initials: Z
authors.lastname: Fan
authors.affiliation: Guangdong Provincial Key Laboratory of Medical Molecular Diagnostics, Dongguan Scientific Research Center, Guangdong Medical University, Dongguan, Guangdong 523808, China.
authors.forename: Pei
authors.initials: P
authors.lastname: Wei
authors.affiliation: Department of Epidemiology, School of Public Health, Guangdong Medical University, Dongguan, Guangdong 523808, China.
authors.forename: Zhigang
authors.initials: Z
authors.lastname: Huang
authors.affiliation: Department of Histology and Embryology of Guangdong Medical University, Guangdong Medical University, Dongguan, Guangdong 523808, China. Electronic address: wangsen@gdmu.edu.cn.
authors.forename: Sen
authors.initials: S
authors.lastname: Wang
authors.affiliation: Guangdong Provincial Key Laboratory of Medical Molecular Diagnostics, Dongguan Scientific Research Center, Guangdong Medical University, Dongguan, Guangdong 523808, China. Electronic address: litao@gdmu.edu.cn.
authors.forename: Tao
authors.initials: T
authors.lastname: Li
mesh_terms: D021581:Active Transport, Cell Nucleus; D019943:Amino Acid Substitution; D001120:Arginine / Q000235:genetics; D002467:Cell Nucleus / Q000378:metabolism; D017124:Conserved Sequence; D006367:HeLa Cells; D000072576:Homeobox Protein Nkx-2.5 / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D008239:Lysine / Q000235:genetics; D019913:Nuclear Localization Signals
chemical_list: D000072576:Homeobox Protein Nkx-2.5; C095552:NKX2-5 protein, human; D019913:Nuclear Localization Signals; D001120:Arginine; D008239:Lysine
keywords: Homeodomain; Motif; NKX2.5; Nuclear localization signal (NLS); Truncated mutant