MicroRNA-17-3p protects against excessive posthypoxic autophagy in H9C2 cardiomyocytes via PTEN-Akt-mTOR signaling pathway.

The activity of phosphatase and tensin homolog (PTEN) can be inhibited by miR-17-3p, which results in attenuating myocardial ischemia/reperfusion injury (IRI), however, the mechanism behind this phenomenon is still elusive. Suppression of PTEN leads to augmented protein kinase B (Akt)/mammalian target of rapamycin (mTOR) signaling strength and constrained autophagy activation, which might be the one mechanism for the ameliorated myocardial IRI. Thus, we tested the hypothesis that miR-17-3p attenuated hypoxia/reoxygenation (H/R)-mediated damage in cardiomyocytes by downregulating excessive autophagy via the PTEN-Akt-mTOR axis. The expression of miR-17-3p was remarkably increased after H/R treatment (6-h hypoxia followed by 6-h reoxygenation; H6/R6), which was concomitant with the increase of the release of lactic acid dehydrogenase (cell injury marker) and the enhancement LC3II/I ratio (autophagy markers) in H9C2 cardiomyocytes. Ectoexpression of miR-17-3p agomir led to remarkable augmentation of miR-17-3p expression and evidently attenuated H/R-mediated cell damage and excessive autophagy. Furthermore, an increase in miR-17-3p expression elicited constrained phosphorylation of PTEN (Ser380 ) while enhanced the phosphorylation of Akt (Thr308 , Ser473 ) and mTOR (Ser536 ) after H/R stimulation. In addition, pretreatment with LY-294002 (an Akt selective inhibitor) and rapamycin (an mTOR selective inhibitor) significantly abrogated the protective function of miR-17-3p on H/R-mediated cell damage and autophagy in H9C2 cardiomyocytes. Taken together, these observations indicated that the enhancement of the PTEN/Akt/mTOR axis and the consequent suppression of autophagy overactivation might represent an underlying mechanism by which miR-17-3p attenuated H/R-mediated damage in H9C2 cells.

[Survival and reproduction of Oncomelania hupensis robertsoni in water network regions in Hubei Province, China].

OBJECTIVE: To understand the possibility of the survival and reproduction of Oncomelania hupensis robertsoni snails in water network regions in Hubei Province, as well as their expected lifespan after leaving the original propagating environment, so as to provide the basic data and precondition for reducing the infection rates of O. h. hupensis in the lake regions. METHODS: The O. h. robertsoni snails, smooth-shell, were collected from Danling County, Sichuan Province,and raised in the cages in Baimasi Town of Jiangling County, Hubei Province. The survival and reproduction abilities of the snails were observed on regular time. The O. h. hupensis from Jiangling County, Hubei Province was studied as a control group. The expected lifespan of snails was calculated by using the animal life table. RESULTS: After 3-, 6-month, the survival rates of O. h. robertsoni were maintained more than 75% in the homogeneous and mixed living conditions, still above 20% after 9-month. Compared with the control group, there was a statistically significant difference in the 3-month group (Chi2 three months = 38.641, P < 0.05), there was a significant difference between the homogeneous and mixed groups for the female snail survival rates (Chi2af = 13.255, P < 0.05, Chi2cg = 4.882, P < 0.05), but not in the 6-, 9-month groups (Chi2 six months = 3.253, P > 0.05; Chi2 nine months = 5.017, P > 0.05). Filial generation snails were found after nine months in each group. The expected lifespan of 0. h. hupensis was 41.16 d and that of O. h. robertsoni was 35.84 d in the laboratory. CONCLUSIONS: The O. h. robertsoni snails from foreign lands can continually survive and reproduce in water network regions in Hubei. O. h. robertsoni snails have enough survival time to passive remote diffusion after leaving the original propagating environments.