Strigolactones interact with other phytohormones to modulate plant root growth and development

Strigolactones(SLs),which are biosynthesized mainly in roots,modulate various aspects of plant growth and development.Here,we review recent research on the role of SLs and their cross-regulation with auxin,cytokinin,and ethylene in the modulation of root growth and development.Under nutrientsufficient conditions,SLs regulate the elongation of primary roots and inhibit adventitious root formation in eudicot plants.SLs promote the elongation of seminal roots and increase the number of adventitious roots in grass plants in the short term,while inhibiting lateral root development in both grass and eudicot plants.The effects of SLs on the elongation of root hairs are variable and depend on plant species,growth conditions,and SL concentration.Nitrogen or phosphate deficiency induces the accumulation of endogenous SLs,modulates root growth and development.Genetic analyses indicate cross-regulation of SLs with auxin,cytokinin,and ethylene in regulation of root growth and development.We discuss the implications of these studies and consider their potential for exploiting the components of SL signaling for the design of crop plants with more efficient soil-resource utilization.

The global regulation of c-di-GMP and cAMP in bacteria

Nucleotide second messengers are highly versatile signaling molecules that regulate a variety of key biological processes in bacteria.The best-studied examples are cyclic AMP(cAMP)and bis-(3'-5')-cyclic dimeric guanosine monophosphate(c-di-GMP),which both act as global regulators.Global regulatory frameworks of c-di-GMP and cAMP in bacteria show several parallels but also significant variances.In this review,we llustrate the global regulatory models of the two nucleotide second messengers,compare the different regulatory frameworks between c-di-GMP and cAMP,and discuss the mechanisms and physiological significance of cross-regulation between c-di-GMP and cAMP.c-di-GMP responds to numerous signals de-pendent on a great number of metabolic enzymes,and it regulates various signal transduction pathways through its huge number of effectors with varying activities.In contrast,due to the limited quantity,the cAMP metabolic enzymes and its major effector are regulated at different levels by diverse signals.cAMP performs its global regulatory function primarily by controlling the transcription of a large number of genes via cAMP receptor protein(CRP)in most bacteria.This review can help us understand how bacteria use the two typical nucleotide second messengers to effectively coordinate and integrate various physiological processes,providing theoretical guidelines for future research.

Tumor microenvironment pathways:Cross regulation in breast cancer metastasis

The tumor microenvironment(TME)is heterogeneous and contains a multiple cell population with surrounded immune cells,which plays a major role in regulating metastasis.The multifunctional pathways,Hedgehog(Hh),Wnt,Notch,and NF-kB,cross-regulates metas-tasis in breast cancer.This review presents substantial evidence for cross-regulation of TME components and signaling pathways,which makes breast TME more heterogeneous and com-plex,promoting breast cancer progression and metastasis as a highly aggressive form.We discoursed the importance of stromal and immune cells as well as their crosstalk in bridging the metastasis.We also discussed the role of Hh and Notch pathways in the intervention be-tween breast cancer cells and macrophages to support TME;Notch signaling in the bidirec-tional communication between cancer cells and components of TME;Wnt signal pathway in controlling the factors responsible for EMT and NF-kB pathway in the regulation of genes con-trolling the inflammatory response.We also present the role of exosomes and their miRNAs in the cross-regulation of TME cells as well as pathways in the reprogramming of breast TME to support metastasis.Finally,we examined and discussed the targeted small molecule inhibitors and natural compounds targeting developmental pathways and proposed small molecule nat-ural compounds as potential therapeutics of TME based on the multitargeting ability.In conclu-sion,the understanding of the molecular basis of the cross-regulation of TME pathways and their inhibitors helps identify molecular targets for rational drug discovery to treat breast can-cers.