NEAP/DUSP26 suppresses receptor tyrosine kinases and regulates neuronal development in zebrafish.

Expression of neuroendocrine-associated phosphatase (NEAP, also named as dual specificity phosphatase 26, [DUSP26]) is restricted to neuroendocrine tissues. We found that NEAP, but not its phosphatase-defective mutant, suppressed nerve growth factor (NGF) receptor TrkA and fibroblast growth factor receptor 1 (FGFR1) activation in PC12 cells upon NGF stimulation. Conversely, suppressing NEAP expression by RNA interference enhanced TrkA and FGFR1 phosphorylation. NEAP was capable of de-phosphorylating TrkA and FGFR1 directly in vitro. NEAP-orthologous gene existed in zebrafish. Morpholino (MO) suppression of NEAP in zebrafish resulted in hyper-phosphorylation of TrkA and FGFR1 as well as abnormal body postures and small eyes. Differentiation of retina in zebrafishes with NEAP MO treatment was severely defective, so were cranial motor neurons. Taken together, our data indicated that NEAP/DUSP26 have a critical role in regulating TrkA and FGFR1 signaling as well as proper development of retina and neuronal system in zebrafish.

Calsyntenin-1, clusterin and neutrophil gelatinase-associated lipocalin are candidate serological biomarkers for lung adenocarcinoma.

It has been drawn attention that secreted proteins with signal peptide from cancer cells provide new potential biomarkers of cancer. In this study, three lung adenocarcinoma cell lines and serum samples from 20 patients were used for identifying potential serologic tumor biomarker with proteomic and bioinformatics approaches. One-dimensional electrophoresis, and identified with mass spectrometry and database research were performed. We found17 secreted proteins in common, while another 17 proteins with signal peptide were identified in all three lung adenocarcinoma cell lines alone with patient samples. With matching these two groups of identified proteins, calsyntenin-1 (CLSTN1), clusterin (CLU) and neutrophil gelatinase-associated lipocalin (NGAL) were found highly secreted from both cell lines and serum with unique signal peptides. Therefore, in our study, we demonstrated that cancer cells secret specific proteins to the environment that may serve as unique markers for cancer diagnosis. To combination of proteomic study with bioinformatic prediction on signal peptides, higher expression level of CLSTN1, CLU and NGAL were found and may be new solid serologic biomarkers for patients with lung adenocarcinoma.

Def6 is required for convergent extension movements during zebrafish gastrulation downstream of Wnt5b signaling.

During gastrulation, convergent extension (CE) cell movements are regulated through the non-canonical Wnt signaling pathway. Wnt signaling results in downstream activation of Rho GTPases that in turn regulate actin cytoskeleton rearrangements essential for co-ordinated CE cell movement. Rho GTPases are bi-molecular switches that are inactive in their GDP-bound stage but can be activated to bind GTP through guanine nucleotide exchange factors (GEFs). Here we show that def6, a novel GEF, regulates CE cell movement during zebrafish gastrulation. Def6 morphants exhibit broadened and shortened body axis with normal cell fate specification, reminiscent of the zebrafish mutants silberblick and pipetail that lack Wnt11 or Wnt5b, respectively. Indeed, def6 morphants phenocopy Wnt5b mutants and ectopic overexpression of def6 essentially rescues Wnt5b morphants, indicating a novel role for def6 as a central GEF downstream of Wnt5b signaling. In addition, by knocking down both def6 and Wnt11, we show that def6 synergises with the Wnt11 signaling pathway.

Mice lacking the Obox6 homeobox gene undergo normal early embryonic development and are fertile.

Obox6 is a member of the Obox (oocyte-specific homeobox) gene family. The Obox6 gene was isolated from the mouse two-cell embryonic cDNA library. Using reverse transcriptase-polymerase chain reaction analysis, we found Obox6 is expressed exclusively in early embryonic stages and exhibits an elevated expression from the two-cell stage to the morula stage. The gene is thought to be involved in early embryogenesis. To study the function of Obox6 in early embryogenesis, we generated Obox6 mutant mice using a gene targeting strategy. Obox6 mutant mice with genetic background of C57BL/6J inbred were born according to Mendelian rules without apparent defects. The mutant mice grew without morphological abnormalities and with normal fertility. The lack of an obvious phenotype in Obox6-null mice and altered RNA levels of some Obox genes raise the possibility that other members of the Obox gene family can compensate for Obox6 function during embryogenesis.

Ohx is a homeobox-encoding gene preferentially expressed in mature oocytes.

There is abundant evidence to indicate that the homeobox genes are developmentally important. We used the NCBI dbEST databases of early mouse embryos to identify novel homeobox-containing sequence tags. Ohx (oocyte-specific homeobox gene) was one of several genes identified by in silico cloning. The full-length Ohx cDNA was cloned and its genomic organization was characterized. The Ohx gene spans 1.6 kb, encodes three exons and maps to the proximal region of mouse chromosome 7. Reverse transcriptase polymerase chain reaction analyses show that Ohx is preferentially expressed in one- and two-cell embryonic stages, as well as in the ovary. Whole mount in situ hybridization analysis demonstrates that the Ohx mRNA was exclusively localized to the oocytes of the mature ovary. Ohx is one of the few homeobox-encoding genes preferentially expressed during mammalian oogenesis.