MiR-1271 negatively regulates AKT/MTOR signaling and promotes apoptosis via targeting PDK1 in pancreatic cancer.

OBJECTIVE: Pancreatic cancer (PC) possesses a very poor prognosis, and its pathogenesis is not fully understood. Evidence has suggested that microRNAs play important roles in cancer development and progression, the present study was designed to study the function of miR-1271 in PC. PATIENTS AND METHODS: PC tissues and adjacent normal tissues were collected from 17 patients. MiR-1271 and PDK1 expression were quantified by quantitative reverse-transcriptional polymerase chain reaction (RT-PCR). AKT/MTOR signaling activity and PDK1 protein expression were determined by Western blot. Cell viability and apoptosis were assessed by MTT assay and enzyme-linked immunosorbent assay (ELISA). Luciferase assay was used to verify whether miR-1271 directly targets PDK1. RESULTS: MiR-1271 was significantly down-regulated in PC tissues compared with that in the paired normal adjacent tissue, and its expression was up-regulated dose-dependently upon cisplatin treatment in PC cells. Overexpression of miR-1271 in these cells produced a pro-apoptotic effect, similar to what caused by cisplatin treatment. Moreover, overexpression of miR-1271 inhibited AKT/MTOR signaling, which was due to the targeting relationship between miR-1271 and PDK1. Finally, knockdown of PDK1 exerted a similar effect on apoptosis to that of miR-1271 overexpression. CONCLUSIONS: MiR-1271 is a potent tumor suppressor in PC, its pro-apoptotic function was partially mediated by reduced AKT/MTOR signaling. Targeting miR-1271 may represent an effective strategy for PC treatment.

The transformer genes in the fig wasp Ceratosolen solmsi provide new evidence for duplications independent of complementary sex determination.

Transformer (tra) is the key gene that turns on the sex-determination cascade in Drosophila melanogaster and in some other insects. The honeybee Apis mellifera has two duplicates of tra, one of which (complementary sex determiner, csd) is the primary signal for complementary sex-determination (CSD), regulating the other duplicate (feminizer). Two tra duplicates have been found in some other hymenopteran species, resulting in the assumption that a single ancestral duplication of tra took place in the Hymenoptera. Here, we searched for tra homologues and pseudogenes in the Hymenoptera, focusing on five newly published hymenopteran genomes. We found three tra copies in the fig wasp Ceratosolen solmsi. Further evolutionary and expression analyses also showed that the two duplicates (Csoltra-B and Csoltra-C) are under positive selection, and have female-specific expression, suggesting possible sex-related functions. Moreover, Aculeata species exhibit many pseudogenes generated by lineage-specific duplications. We conclude that phylogenetic reconstruction and pseudogene screening provide novel evidence supporting the hypothesis of independent duplications rather an ancestral origin of multiple tra paralogues in the Hymenoptera. The case of C. solmsi is the first example of a non-CSD species with duplicated tra, contrary to the previous assumption that derived tra paralogues function as the CSD locus.

Diversity and evolution of Ty1-copia retroelements within Chalcidoidea by reverse transcriptase domain analysis.

Ty1-copia retrotransposons are widespread and diverse in insects. Some features of their hosts, such as mating and genetic systems, are predicted to influence the spread of selfish genetic elements like Ty1-copia. Using part of the reverse transcriptase gene as a reference, we experimentally surveyed Ty1-copia elements in eight species of fig wasps (Hymenoptera: Chalcidoidea), and performed an in silico analysis of six available genomes of chalcid wasps. Contrary to initial expectations that selfish elements such as Ty1-copia would be purged from the genomes of these species because of inbreeding and haplodiploidy, almost all of these wasps harbour an abundance of diverse Ty1-copia elements. Phylogenetic analyses suggest that the families of Ty1-copia elements found in these species have had a long association with their chalcid hosts. These results suggest an evolutionary scenario in which there was ancestral polymorphism followed by some taxa-specific events including stochastic loss and further diversification. Furthermore, estimating natural selection within the internal and terminal portions of the Ty1-copia phylogenies demonstrated that the elements are under strong evolutionary constraints for their long-term survival, but evolve like pseudogenes in the short term, accompanied by the rise and fall of parasitic elements in the history of wasp lineage.

Rampant host switching and multiple female body colour transitions in Philotrypesis (Hymenoptera: Chalcidoidea: Agaonidae).

Figs (Ficus, Moraceae) and their associated fig waSPS (Hymenoptera, Chalcidoidea and Agaonidae) have attracted much attention and have been used as a model system for many studies. Fig waSPS belonging to the genus Philotrypesis are very common in most figs but their taxonomy, ecology and biology are currently poorly explored. A previous study on African Philotrypesis showed that their host association is phylogenetically conserved at subsection level. We reconstructed a molecular phylogeny with extended sampling from seven sections of figs. Our study suggested that the diversification of Philotrypesis is less constrained by host figs. Host switching is rampant between figs at species level and even at section level. We also investigated the evolution of the body colour forms in female Philotrypesis. Our study first suggested that female body colour is not evolutionarily stable and that there have been multiple transitions. Possible mechanisms for multiple colour transitions are expected to be determined in the near future.

Stochastic exclusion processes with extended hopping.

We study the effects of extended hopping in the stochastic asymmetric simple exclusion process (ASEP) of one dimension. A modified ASEP with four parameters is proposed. The current and bulk density are calculated. Two different phases with a curved boundary are observed. The phase of maximum current is absent. We also present the unusual density fluctuations near both boundaries. The characteristic of the stochastic dynamics with extended hopping is pointed out.