Optogenetics in oral and craniofacial research

Optogenetics combines optics and genetic engineering to control specific gene expression and biological functions and has the advantages of precise spatiotemporal control,noninvasiveness,and high efficiency.Genetically modified photosensory sensors are engineered into proteins to modulate conformational changes with light stimulation.Therefore,optogenetic techniques can provide new insights into oral biological processes at different levels,ranging from the subcellular and cellular levels to neural circuits and behavioral models.Here,we introduce the origins of optogenetics and highlight the recent progress of optogenetic approaches in oral and craniofacial research,focusing on the ability to apply optogenetics to the study of basic scientific neural mechanisms and to establish different oral behavioral test models in vivo(orofacial movement,licking,eating,and drinking),such as channelrhodopsin(ChR),archaerhodopsin(Arch),and halorhodopsin from Natronomonas pharaonis(NpHR).We also review the synergic and antagonistic effects of optogenetics in preclinical studies of trigeminal neuralgia and maxillofacial cellulitis.In addition,optogenetic tools have been used to control the neurogenic differentiation of dental pulp stem cells in translational studies.Although the scope of optogenetic tools is increasing,there are limited large animal experiments and clinical studies in dental research.Potential future directions include exploring therapeutic strategies for addressing loss of taste in patients with coronavirus disease 2019(COVID-19),studying oral bacterial biofilms,enhancing craniomaxillofacial and periodontal tissue regeneration,and elucidating the possible pathogenesis of dry sockets,xerostomia,and burning mouth syndrome.

Transcriptomic but not genomic variability confers phenotype of breast cancer stem cells

Background:Breast cancer stem cells(BCSCs)are considered responsible for cancer relapse and drug resistance.Understanding the identity of BCSCs may open new avenues in breast cancer therapy.Although several discoveries have been made on BCSC characterization,the factors critical to the origination of BCSCs are largely unclear.This study aimed to determine whether genomic mutations contribute to the acquisition of cancer stem-like phenotype and to investigate the genetic and transcriptional features of BCSCs.Methods:We detected potential BCSC phenotype-associated mutation hotspot regions by using whole-genome sequencing on parental cancer cells and derived serial-generation spheres in increasing order of BCSC frequency,and then performed target deep DNA sequencing at bulk-cell and single-cell levels.To identify the transcriptional program associated with BCSCs,bulk-cell and single-cell RNA sequencing was performed.Results:By using whole-genome sequencing of bulk cells,potential BCSC phenotype-associated mutation hotspot regions were detected.Validation by target deep DNA sequencing,at both bulk-cell and single-cell levels,revealed no genetic changes specifically associated with BCSC phenotype.Moreover,single-cell RNA sequencing showed profound transcriptomic variability in cancer cells at the single-cell level that predicted BCSC features.Notably,this transcriptomic variability was enriched during the transcription of 74 genes,revealed as BCSC markers.Breast cancer patients with a high risk of relapse exhibited higher expression levels of these BCSC markers than those with a low risk of relapse,thereby highlighting the clinical significance of predicting breast cancer prognosis with these BCSC markers.Conclusions:Transcriptomic variability,not genetic mutations,distinguishes BCSCs from non-BCSCs.The identified 74 BCSC markers have the potential of becoming novel targets for breast cancer therapy.