Spotlight

MAPK Signaling: Emerging Roles in Lateral Root Formation

Plants possess multiple protective mechanisms against abiotic stress which ensure their survival in limiting environments. Among those stressors, low light is an emerging cue for plants. Light is crucial to control the plant life as fuels photosynthesis which is strictly dependent to light intensity, duration and quality. In addition, plants are equipped with multiple photoreceptors (e.g. phytochromes, cryptochromes, and phototropin) that sense light and trigger light-mediated molecular/physiological responses. Fluctuations in light spectra and flux density, impact on plant performance at morphological, physiological, biochemical and molecular level, leading to severe alteration in plant growth and development. As sessile organisms, plants cannot escape light stress, thus, they have evolved specific mecanisms of adaptation to such conditions, including a complex network of phytohormones. In this review, we summarize the recent findings dealing with the regulation of plant response to low light, with a focus on the role(s) of phytohormones involved in such light-limited environments.

Foods prepared by fermentation with Saccharomyces cerevisiae sometimes require co-cultivation with lactic acid bacteria (LAB) or other microorganisms. Co-cultured LAB could compete for nutrients, thereby affecting central metabolism of S. cerevisiae cells; as a result, the oxidative metabolism of yeast might also be influenced. Here, S. cerevisiae ATCC 204508 was co-cultivated with Lactobacillus plantarum ATCC 8014 to evaluate its regulation effects on the oxidative metabolism in yeast cells. Results indicated that co-cultured L. plantarum did not exacerbate membrane lipid peroxidation but reduced intracellular reactive oxygen species (ROS) content of yeast. L. plantarum initiated NADPH oxidase by activation of Ca²⁺ signaling and MAPK pathways, thereby promoting the ROS generation in S. cerevisiae cells. To cope with the increased ROS generation, both enzymatic and non-enzymatic defense systems were activated, accounting for the decreased intracellular ROS level in yeast cells that co-cultured with L. plantarum. At the same time, activated anti-oxidation system also conferred higher oxidative tolerance to yeast cells, which could be considered a desirable characteristic for fermentation using S. cerevisiae. The co-cultivation of L. plantarum also activated energy metabolism and promoted ATP production in yeast. These results will contribute to the understanding of the complex relationship between S. cerevisiae and LAB during fermentation.

This article summarizes natural products that target the MAPK-signaling pathway in cancer therapy. The classification, chemical structures, and anti-cancer mechanisms of these natural products are elucidated, and comprehensive information is provided on their potential use in cancer therapy.

Using the PubMed database, we searched for keywords, including “tumor”, “cancer”, “natural product”, “phytochemistry”, “plant chemical components”, and “MAPK-signaling pathway”. We also screened for compounds with well-defined structures that targeting the MAPK-signaling pathway and have anti-cancer effects. We used Kingdraw software and Adobe Photoshop software to draw the chemical compound structural diagrams.

A total of 131 papers were searched, from which 85 compounds with well-defined structures were selected. These compounds have clear mechanisms for targeting cancer treatment and are mainly related to the MAPK-signaling pathway. Examples include eupatilin, carvacrol, oridonin, sophoridine, diosgenin, and juglone. These chemical components are classified as flavonoids, phenols, terpenoids, alkaloids, steroidal saponins, and quinones.

Certain MAPK pathway inhibitors have been used for clinical treatment. However, the clinical feedback has not been promising because of genomic instability, drug resistance, and side effects. Natural products have few side effects, good medicinal efficacy, a wide range of sources, individual heterogeneity of biological activity, and are capable of treating disease from multiple targets. These characteristics make natural products promising drugs for cancer treatment.