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Wen-Bin Liu,
Qin Yan,
Fang-Yuan Liu,
Xiangcheng Tang,
He-Ge Chen, Jiao Liu,
Nie Lei,
Xu-Wen Zhang,
Weike Ji,
Xiao-Hui Hu,
Wenfeng Hu,
Zachary Woodward,
Kali Wu,
Mingxing Wu,
Xialin Liu,
Lixia Luo,
Minbin Yu,
Yizhi Liu,
Shao-Jun Liu,
David Wan-Cheng Li
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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; · 5.10 Impact Factor
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J Liu,
W Ji,
S Sun,
L Zhang,
H-G Chen,
Y Mao,
L Liu,
X Zhang,
L Gong,
M Deng, [......],
P-C Chen,
W-F Hu,
X Hu,
Z Woodward,
W-B Liu,
Y-M Xiao,
S-P Liang,
Y Liu,
S-J Liu,
D W-C Li
[show abstract]
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ABSTRACT: Protein phosphatase-2A (PP-2A) is a major serine/threonine phosphatase abundantly expressed in eukaryotes. PP-2A is a heterotrimer that contains a 65kD scaffold A subunit, a 36kD catalytic C subunit, and a regulatory B subunit of variable isoforms ranging from 54-130kDs. The scaffold subunits, PP2A-Aα/β, act as platforms for both the C and B subunits to bind, and thus are key structural components for PP-2A activity. Mutations in both genes encoding PP2A-Aα and PP2A-Aβ lead to carcinogenesis and likely other human diseases. Our previous work showed that the gene coding for PP2A-Aα is positively regulated by multiple transcription factors including Ets-1, CREB, and AP-2α but negatively regulated by SP-1/SP-3. In the present study, we have functionally dissected the promoter of the mouse PP2A-Aβ gene. Our results demonstrate that three major cis-elements, including the binding sites for Ets-1, SP1/SP3, and RXRα/β, are present in the proximal promoter of the mouse PP2A-Aβ gene. Gel mobility shifting assays reveal that Ets-1, SP1/SP3, and RXRα/β all bind to PP2A-Aβ gene promoter. In vitro mutagenesis and reporter gene activity assays demonstrate that while Ets-1 displays negative regulation, SP1/SP3 and RXRα/β positively regulate the promoter of the PP2A-Aβ gene. Co-expression of the cDNAs encoding Ets-1, SP1/SP3, or RXRα/β and the luciferase reporter gene driven by PP2A-Aβ promoter further confirm their control over the PP2A-Aβ promoter. Finally, ChIP assays demonstrate that Ets-1, SP1/SP3, and RXRα/β can all bind to the PP2A-Aβ gene promoter. Together, our results reveal that multiple transcription factors regulate the PP2A-Aβ gene. Moreover, our results provide important information explaining why PP2A-Aα and PP2A-Aβ display distinct expression levels.
Current Molecular Medicine 07/2012; 12(8):982-94. · 5.10 Impact Factor
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F-Y Liu,
X-C Tang,
M Deng,
P Chen,
W Ji,
X Zhang,
L Gong,
Z Woodward, J Liu,
L Zhang,
S Sun,
J-P Liu,
K Wu,
M-X Wu,
X-L Liu,
M-B Yu,
Y Liu,
D W-C Li
[show abstract]
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ABSTRACT: The tumor suppressor p53 plays a key role in regulating apoptosis and cell cycle progression. In addition, p53 is implicated in control of cell differentiation in muscle, the circulatory system, ocular lens and various carcinoma tissues. However, the mechanisms by which p53 controls cell differentiation are not fully understood. Here we present evidence that p53 directly regulates c-Maf and Prox1, two important transcription factors controlling differentiation in the ocular lens. First, human and murine c-Maf and Prox1 gene promoters contain authentic p53 DNA binding sites. Second, p53 directly binds to the p53 binding sites found in the promoter regions. Third, exogenous p53 induces dose-dependent expression of the luciferase report gene driven by both c-Maf and Prox1 promoters, and p53 binds to both promoters in the ChIP assays. Fourth, in the in vitro differentiation model, knockdown of p53 significantly inhibits lens differentiation which is associated with downregulated expression of c-Maf and Prox1. Finally, in p53 knockout mice, the expression of c-Maf and Prox1 are significantly altered. Together, our results reveal that p53 regulates lens differentiation through modulation of two important transcription factors, c-Maf and Prox1, and through them p53 thus controls expression of various differentiation-related downstream crystallin genes.
Current Molecular Medicine 07/2012; 12(8):917-28. · 5.10 Impact Factor
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M Deng,
P Chen,
F Liu,
S Fu,
H Tang,
Y Fu,
Z Xiong,
S Hui,
W Ji,
X Zhang, [......],
X Hu,
W Hu,
S Sun,
J Liu,
L Xiao,
W-B Liu,
Y-M Xiao, S-J Liu,
Y Liu,
D W-C Li
[show abstract]
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ABSTRACT: The tumor suppressor p53 is a master regulator of apoptosis and also plays a key role in cell cycle checking. In our previous studies, we demonstrated that p53 directly regulates Bak in mouse JB6 cells (Qin et al. 2008. Cancer Research. 68(11):4150) and that p53-Bak signaling axis plays an important role in mediating EGCG-induced apoptosis. Here, we demonstrate that the same p53-Bak apoptotic signaling axis executes an essential role in regulating lens cell differentiation. First, during mouse lens development, p53 is expressed and differentially phosphorylated at different residues. Associated with p53 expression, Bak is also significantly expressed during mouse lens development. Second, human p53 directly regulates Bak promoter and Bak expression in p53 knockout mice (p53-/-) was significantly downregulated. Third, during in vitro bFGF-induced lens cell differentiation, knockdown of p53 or Bak leads to significant inhibition of lens cell differentiation. Fourth, besides the major distribution of Bak in cytoplasm, it is also localized in the nucleus in normal lens or bFGF-induced differentiating lens cells. Finally, p53 and Bak are co-localized in both cytoplasm and nucleus, and their interaction regulates the stability of p53. Together, these results demonstrate for the first time that the p53-Bak apoptotic signaling axis plays an essential role in regulating lens differentiation.
Current Molecular Medicine 06/2012; 12(8):901-16. · 5.10 Impact Factor
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Lan Zhang,
Shuming Sun,
Jie Zhou, Jiao Liu,
Jia-Han Lv,
Xiang-Qiang Yu,
Chi Li,
Lili Gong,
Qin Yan,
Mi Deng,
Ling Xiao,
Haili Ma,
Jin-Ping Liu,
Yun-Lei Peng,
Dao Wang,
Gao-Peng Liao,
Li-Jun Zou,
Wen-Bin Liu,
Ya-Mei Xiao,
David Wan-Cheng Li
[show abstract]
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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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Qin Yan,
Lili Gong,
Mi Deng,
Lan Zhang,
Shuming Sun, Jiao Liu,
Haili Ma,
Dan Yuan,
Pei-Chao Chen,
Xiaohui Hu,
Jinping Liu,
Jichao Qin,
Ling Xiao,
Xiao-Qin Huang,
Jian Zhang,
David Wan-Cheng Li
[show abstract]
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ABSTRACT: Pax-6 is an evolutionarily conserved transcription factor regulating brain and eye development. Four Pax-6 isoforms have been reported previously. Although the longer Pax-6 isoforms (p46 and p48) bear two DNA-binding domains, the paired domain (PD) and the homeodomain (HD), the shorter Pax-6 isoform p32 contains only the HD for DNA binding. Although a third domain, the proline-, serine- and threonine-enriched activation (PST) domain, in the C termini of all Pax-6 isoforms mediates their transcriptional modulation via phosphorylation, how p32 Pax-6 could regulate target genes remains to be elucidated. In the present study, we show that sumoylation at K91 is required for p32 Pax-6 to bind to a HD-specific site and regulate expression of target genes. First, in vitro-synthesized p32 Pax-6 alone cannot bind the P3 sequence, which contains the HD recognition site, unless it is preincubated with nuclear extracts precleared by anti-Pax-6 but not by anti-small ubiquitin-related modifier 1 (anti-SUMO1) antibody. Second, in vitro-synthesized p32 Pax-6 can be sumoylated by SUMO1, and the sumoylated p32 Pax-6 then can bind to the P3 sequence. Third, Pax-6 and SUMO1 are colocalized in the embryonic optic and lens vesicles and can be coimmunoprecipitated. Finally, SUMO1-conjugated p32 Pax-6 exists in both the nucleus and cytoplasm, and sumoylation significantly enhances the DNA-binding ability of p32 Pax-6 and positively regulates gene expression. Together, our results demonstrate that sumoylation activates p32 Pax-6 in both DNA-binding and transcriptional activities. In addition, our studies demonstrate that p32 and p46 Pax-6 possess differential DNA-binding and regulatory activities.
Proceedings of the National Academy of Sciences 11/2010; 107(49):21034-9. · 9.68 Impact Factor
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Mi Deng,
Pei-Chao Chen,
Sisi Xie,
Junqiong Zhao,
Lili Gong,
Jinping Liu,
Lan Zhang,
Shuming Sun, Jiao Liu,
Haili Ma,
Surinder K Batra,
David Wan-Cheng Li
[show abstract]
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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. · 2.42 Impact Factor
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Hai-Li Ma,
Yun-Lei Peng,
Lili Gong,
Wen-Bin Liu,
Shuming Sun, Jiao Liu,
Chun-Bing Zheng,
Hu Fu,
Dan Yuan,
Junqiong Zhao,
Pei-Chao Chen,
Si-si Xie,
Xiao-Ming Zeng,
Ya-Mei Xiao,
Yun Liu,
David Wan-Cheng Li
[show abstract]
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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.
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ABSTRACT: This paper investigates the features of GSCs in the process of the gonad development of sex reversal in Monopterus albus by the histological methods and the histological immunochemical techniques. In Monopterus albus, the GSCs are located in the gonadal lamellae,which are scattered or accumulated during the female phase. In the intersex and the male,the GSCs are distinguished by two types A and B, both of them differ from the GSCs at the female stage in ultrastructure. It shows that the GSCs existing in the gonadal lamellae are the unique germ family, which owns the capability of mitosis in the differential gonads. The GSCs represent the ovogonia in the female phase, while the spermagonia in the intersex and the male phases. CD49 is the molecular marker for the GSCs at the female stage and the GSCs of type A.
Journal of Molecular Cell Biology 07/2007; 40(3):196-204.
