No abstract

Noble metal nanoclusters (NCs) have emerged as a new class of nanomaterials which have great potential in bioapplications. Due to their ultrasmall size and versatile surface chemistry, they show excellent luminescence, high photostability, good biocompatibility, low toxicity, and a high renal clearance rate. In recent years, much work has been reported toward the bioapplications of metal NCs, especially the Au, Ag, and Cu NCs. In this Review, we first discuss the crucial factors of metal NCs for their use as biomaterials, including the size, surface chemistry, photoluminescent properties, cytotoxicity, and metabolic activity. Then, we highlight some recent advances of metal NCs in bioapplications, such as biosensing, bioimaging, biomedical diagnosis, and therapy. It is noteworthy that the metal NCs perform quite well in cancer treatment. Finally, we have briefly discussed the current challenges and our perspectives on metal NCs in bioapplication research and further transformation into clinical application.

The pineal gland hormone melatonin exerts its regulatory roles in a variety of physiological and pathological responses through two G protein-coupled receptors, melatonin receptor type 1 (MT1) and melatonin receptor type 2 (MT2), which have been recognized as promising targets in the treatment of a number of human diseases and disorders. The MT1 receptor was identified nearly 20 years ago; however, the molecular mechanisms by which MT1-mediated signaling affects physiology remain to be further elucidated. In this study, using HEK293 cells stably expressing the human MT1 receptor, melatonin induced a concentration-dependent activation of extracellular signal-regulated kinase 1 and 2 (ERK1/2). The melatonin-mediated phosphorylation of ERK1/2 at later time points (≥5 min) was strongly suppressed by pretreatment with pertussis toxin, but only a slight, if any, inhibition of ERK1/2 activation at early time points (≤2 min) was detected. Further experiments demonstrated that the Gβγ subunit, phosphoinositide 3-kinase, and calcium-insensitive protein kinase C were involved in the MT1-mediated activation of ERK1/2 at later time points (≥5 min). Moreover, results derived from cAMP assays combined with a MT1 mutant indicated that the human MT1 receptor could also couple to Gs protein, stimulating intracellular cAMP formation, and that the MT1-induced activation of ERK1/2 at early time points (≤2 min) was mediated by the Gs/cAMP/PKA cascade. Our findings may provide new insights into the pharmacological effects and physiological functions modulated by the MT1-mediated activation of ERK1/2.

Background: The corazonin system is of importance for insects to control multiple physiological processes.Results: Bombyx BNGR-A21 was activated in signaling and internalization by direct interaction with corazonin.Conclusion: Bombyx corazonin was a specific ligand for dual Gq- and Gs-coupled BmCrzR.Significance: Our findings will lead to a better understanding of the corazonin system in regulation of fundamental physiological processes.

Background: AKH/AKHR system is of importance for insects to control energy homeostasis. Results: Bombyx BNGR-A28 and BNGR-A29 were activated in signaling and internalization by AKH3 at high affinity but not by corazonin. Conclusion: AKH3 was a specific ligand for two orphan GPCRs, AKHR2a and AKHR2b. Significance: Our findings will lead to a better understanding of the AKH/AKHR system in regulation of fundamental physiological processes.