The Division of Infectious Diseases, Los Angeles Biomedical Research Institute at Harbor, University of California Los Angeles (UCLA) Medical Center, Los Angeles, California, USA
Division of Infectious Diseases, Children's Hospital, Boston, Massachusetts, USA.
mBio. 2018 Aug 21;9(4):e01338-18. doi: 10.1128/mBio.01338-18.
surface-attached biofilms such as those formed on intravenous catheters with direct access to the bloodstream often serve as a nidus for continuous release of cells capable of initiating new infectious foci. We previously reported that cells dispersed from a biofilm are yeast cells that originate from the top-most hyphal layers of the biofilm. Compared to their planktonic counterparts, these biofilm dispersal yeast cells displayed enhanced virulence-associated characteristics and drug resistance. However, little is known about their molecular properties. To address that issue, in this study we aimed to define the molecular characteristics of these biofilm dispersal cells. We found that the inducer of dispersal, , genetically interacts with the repressor of filamentation, , in a manner consistent with the definition of dispersed cells as yeast cells. Further, using a flow biofilm model, we performed comprehensive comparative RNA sequencing on freshly dispersed cells in order to identify unique transcriptomic characteristics. Gene expression analysis demonstrated that dispersed cells largely inherit a biofilm-like mRNA profile. Strikingly, however, dispersed cells seemed transcriptionally reprogrammed to acquire nutrients such as zinc and amino acids and to metabolize alternative carbon sources, while their biofilm-associated parent cells did not induce the same high-affinity transporters or express gluconeogenetic genes, despite exposure to the same nutritional signals. Collectively, the findings from this study characterize cell dispersal as an intrinsic step of biofilm development which generates propagules more adept at colonizing distant host sites. This developmental step anticipates the need for virulence-associated gene expression before the cells experience the associated external signals. surface-attached biofilms serve as a reservoir of cells to perpetuate and expand an infection; cells released from biofilms on catheters have direct access to the bloodstream. Biofilm dispersal yeast cells exhibit enhanced adhesion, invasion, and biofilm formation compared to their planktonic counterparts. Here, we show using transcriptome sequencing (RNA-seq) that dispersed yeast cells are developmentally distinct from the cells in their parent biofilms as well as from planktonic yeast cells. Dispersal cells possess an anticipatory expression pattern that primes them to infect new sites in the host, to survive in nutrient-starved niches, and to invade new sites. These studies identified dispersal cells as a unique proliferative cell type of the biofilm and showed that they could serve as targets for antibiofilm drug development in the future.
附着于表面的生物膜，如直接与血流接触的静脉导管上形成的生物膜，常作为持续释放能够引发新感染灶的细胞的病灶。我们之前曾报道过，从生物膜中分散出来的细胞是源自生物膜最上层丝状层的酵母细胞。与浮游细胞相比，这些生物膜分散的酵母细胞表现出增强的毒力相关特征和耐药性。然而，人们对它们的分子特性知之甚少。为了解决这个问题，在这项研究中，我们旨在确定这些生物膜分散细胞的分子特征。我们发现，分散诱导物 ，与丝状形成抑制剂 ，在遗传上相互作用，这与分散细胞作为酵母细胞的定义一致。此外，我们使用流动生物膜模型，对刚分散的细胞进行了全面的比较 RNA 测序，以确定独特的转录组特征。基因表达分析表明，分散细胞在很大程度上继承了生物膜样的 mRNA 谱。然而，令人惊讶的是，与生物膜相关的母细胞不同，分散细胞似乎在转录水平上被重新编程，以获取锌和氨基酸等营养物质，并代谢替代碳源，而其母细胞尽管暴露在相同的营养信号下，也没有诱导相同的高亲和力转运蛋白或表达糖异生基因。总的来说，这项研究的结果将细胞分散描述为生物膜发育的一个内在步骤，它产生更善于定植远处宿主部位的繁殖体。这种发育步骤预测了细胞在遇到相关外部信号之前，需要表达与毒力相关的基因。附着于表面的生物膜是维持和扩大感染的细胞库；从导管上的生物膜中释放的细胞直接进入血流。与浮游细胞相比，从生物膜中释放的酵母细胞表现出增强的粘附、侵袭和生物膜形成能力。在这里，我们使用转录组测序 (RNA-seq) 显示，与母生物膜中的细胞以及浮游酵母细胞相比，分散的酵母细胞在发育上是不同的。分散细胞具有一种预期的表达模式，使它们能够感染宿主的新部位，在营养饥饿的小生境中生存，并侵入新部位。这些研究将分散细胞确定为生物膜的一种独特增殖细胞类型，并表明它们可能成为未来抗生物膜药物开发的靶点。
