Jiao Liu

University of Nebraska at Omaha, Omaha, NE, United States

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Publications (5)19.18 Total impact

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    ABSTRACT: Protein serine/threonine phosphatase-1 (PP1) is one of the key enzymes responsible for dephosphorylation in vertebrates. Protein dephosphorylation via PP1 is implicated in many different biological processes including gene expression, cell cycle control, transformation, neuronal transmission, apoptosis, autophage and senescence. However, whether PP1 directly controls animal development remains to be investigated. Here, we present direct evidence to show that PP1 plays an essential role in regulating eye development of vertebrates. Using goldfish as a model system, we have shown the following novel results. First, inhibition of PP1 activity leads to death of a majority of the treated embryos, and the survived embryos displayed severe phenotype in the eye. Second, knockdown of each catalytic subunit of PP1 with morpholino oligomers leads to partial (PPl knockdown) or complete (PPl or PPl knockdown) death of the injected embryos. The survived embryos from PP1 knockdown displayed clear retardation in lens differentiation. Finally, overexpression of each subunit of PP1 also causes death of majority of the injected embryos and leads to abnormal development of goldfish eye. Mechanistically, Pax-6 is one of the major downstream target mediating the effects of PP1 function since the eye phenotype in Pax-6 knockdown fish is similar to that derived from overexpression of PP1. Together, our results for the first time provide direct evidence that protein phosphatase-1 plays a key role in governing normal eye formation during goldfish development.
    Current Molecular Medicine 09/2012; · 4.20 Impact Factor
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    ABSTRACT: The Akt signaling pathway plays a key role in promoting the survival of various types of cells from stress-induced apoptosis, and different members of the Akt family display distinct physiological roles. Previous studies have shown that in response to UV irradiation, Akt2 is sensitized to counteract the induced apoptosis. However, in response to oxidative stress such as hydrogen peroxide, it remains to be elucidated what member of the Akt family would be activated to initiate the signaling cascades leading to resistance of the induced apoptosis. In the present study, we present the first evidence that knockdown of Akt1 enhances cell survival under exposure to 50 μM H(2)O(2). This survival is derived from selective upregulation and activation of Akt2 but not Akt3, which initiates 3 major signaling cascades. First, murine double minute 2 (MDM2) is hyperphosphorylated, which promotes p53 degradation and attenuates its Ser-15 phosphorylation, significantly attenuating Bcl-2 homologous antagonist killer (Bak) upregulation. Second, Akt2 activation inactivates glycogen synthase kinase 3 beta (GSK-3β) to promote stability of myeloid leukemia cell differentiation protein 1 (MCL-1). Finally, Akt2 activation promotes phosphorylation of FOXO3A toward cytosolic export and thus downregulates Bim expression. Overexpression of Bim enhances H(2)O(2)-induced apoptosis. Together, our results demonstrate that among the Akt family members, Akt2 is an essential kinase in counteracting oxidative-stress-induced apoptosis through multiple signaling pathways.
    Antioxidants & Redox Signaling 02/2011; 15(1):1-17. · 8.20 Impact Factor
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    ABSTRACT: The small heat shock protein alphaA-crystallin is a structural protein in the ocular lens. In addition, recent studies have also revealed that it is a molecular chaperone, an autokinase and a strong anti-apoptotic regulator. Besides its lenticular distribution, a previous study demonstrates that a detectable level of alphaA-crystallin is found in other tissues including thymus and spleen. In the present study, we have re-examined the distribution of alphaA-crystallin in various normal human and mouse tissues and found that the normal pancreas expresses a moderate level of alphaA-crystallin. Moreover, alphaA-crystallin is found significantly downregulated in 60 cases of pancreatic carcinoma of different types than it is in 11 normal human pancreas samples. In addition, we demonstrate that alphaA-crystallin can enhance the activity of the activating protein-1 (AP-1) through modulating the function of the MAP kinase, and also upregulates components of TGFbeta pathway. Finally, expression of alphaA-crystallin in a pancreatic cancer cell line, MiaPaCa, results in retarded cell migration. Together, these results suggest that alphaA-crystallin seems to negatively regulate pancreatic carcinogenesis.
    Biochimica et Biophysica Acta 04/2010; 1802(7-8):621-31. · 4.66 Impact Factor
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    ABSTRACT: The c-Jun N-terminal kinases (JNKs) are members of the mitogen-activated protein kinase family. Their functions in regulating animal development have been well studied in both invertebrates and vertebrates. However, it remains to be determined whether they play a role in sex determination. Here we present first evidence to show that expression of JNK1 displays distinct patterns during sex reversal of rice-field eel. Molecular cloning reveals that JNK1 is well conserved among rice-field eel and other vertebrates. Both quantitative real-time polymerase chain reaction and Western blot analysis demonstrate that JNK1 is highly expressed in the ovary of the female individual and reduced to a substantial degree at the later stage of the intersex. However, when the intersex individual develops into the stage of male, expression of the JNK1 in the testis of the male individual is distinctly downregulated. Associated with the contrast JNK1 expression pattern in female and male gonads, several stem cell marker genes including Nanog, Oct-3/4, and Sox-2 were also differentially expressed in female and male germinal stem cells. Together, these results suggest it is possible that JNK1 plays an important role in sexual reversal of the rice-field eel.
    Journal of Experimental Zoology Part B Molecular and Developmental Evolution 11/2009; 314(3):242-56. · 2.12 Impact Factor
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    ABSTRACT: SG2NA is a member of the striatin protein family. In human and mouse, the SG2NA gene encodes two major protein isoforms: SG2NA alpha and SG2NA beta. The functions of these proteins, except for acting as the regulatory subunits for PP-2A, remain largely unknown. To explore the possible functions of SG2NA in lower vertebrates, we have isolated two SG2NA cDNAs from goldfish, Carassius auratus. Our results reveal that the first cDNA contains an ORF of 2118 bp encoding a deduced protein with 705 amino acids, and the second one 2148 bp coding for a deduced protein of 715 amino acids. Comparative analysis reveals that both isoforms belong to the alpha-type, and are named SG2NA alpha and SG2NA alpha(+). RT-PCR and western blot analysis reveal that the SG2NA gene is differentially expressed in 9 tissues examined. During goldfish development, while the SG2NA mRNAs remain relatively constant in the first 3 stages and then become decreased and fluctuated from gastrula to larval hatching, the SG2NA proteins are fluctuated, displaying a peak every 3 to 4 stages. Each later peak is higher than the earlier one and the protein expression level becomes maximal at hatching stage. Together, our results reveal that SG2NA may play an important role during goldfish development and also in homeostasis of most adult tissues.
    Gene regulation and systems biology 01/2009; 3:115-29.

Publication Stats

18 Citations
19.18 Total Impact Points

Institutions

  • 2010–2012
    • University of Nebraska at Omaha
      • Department of Biochemistry and Molecular Biology
      Omaha, NE, United States
  • 2011
    • University of Nebraska Medical Center
      Omaha, Nebraska, United States
  • 2009
    • Hunan University
      Ch’ang-sha-shih, Hunan, China