Lysophosphatidic acids (LPA) exert multiple biological effects through specific G protein-coupled receptors. The LPA-activated receptor subtype LPA(2) contains a carboxyl-terminal motif that allows interaction with PDZ domain-containing proteins, such as NHERF2 and PDZ-RhoGEF. To identify additional interacting partners of LPA(2), the LPA(2) carboxyl-terminus was used to screen a proteomic array of PDZ domains. In addition to the previously identified NHERF2, several additional LPA(2)-interacting PDZ domains were found. These included MAGI-2, MAGI-3 and neurabin. In the present work, we demonstrate the specific interaction between LPA(2) and MAGI-3, and the effects of MAGI-3 in colon cancer cells using SW480 as a cell model. MAGI-3 specifically bound to LPA(2), but not to LPA(1) and LPA(3). This interaction was mediated via the fifth PDZ domain of MAGI-3 interacting with the carboxyl-terminal 4 amino acids of LPA(2), and mutational alteration of the carboxyl-terminal sequences of LPA(2) severely attenuated its ability to bind MAGI-3. LPA(2) also associated with MAGI-3 in cells as determined by co-affinity purification. Overexpression of MAGI-3 in SW480 cells showed no apparent effect on LPA-induced activation of Erk and Akt. In contrast, silencing of MAGI-3 expression by siRNA drastically inhibited LPA-induced Erk activation, suggesting that the lack of an effect by overexpression was due to the high endogenous MAGI-3 level in these cells. Previous studies have shown that the cellular signaling elicited by LPA results in activation of the small GTPase RhoA by Galpha(12/13) - as well as Galpha(q)-dependent pathways. Overexpression of MAGI-3 stimulated LPA-induced RhoA activation, whereas silencing of MAGI-3 by siRNA resulted in a small but statistically significant decrease in RhoA activation. These results demonstrate that MAGI-3 interacts directly with LPA(2) and regulates the ability of LPA(2) to activate Erk and RhoA.

Cucumber belongs to the family Cucurbitaceae (melon genus) and is an annual herbaceous vegetable crop. Cucumber is an important cash crop that is grown all over the world. From morphology to cytology, from canonical genetics to molecular biology, researchers have performed much research on sex differentiation and its regulatory mechanism in cucumber, mainly in terms of cucumber sex determination genes, environmental conditions, and the effects of plant hormones, revealing its genetic basis to improve the number of female flowers in cucumber, thus greatly improving the yield of cucumber. This paper reviews the research progress of sex differentiation in cucumber in recent years, mainly focusing on sex-determining genes, environmental conditions, and the influence of phytohormones in cucumber, and provides a theoretical basis and technical support for the realization of high and stable yield cultivation and molecular breeding of cucumber crop traits.

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