Department of Medical Oncology and Center for Functional Cancer Epigenetics, Dana-Farber Cancer Institute, Boston, MA 02215, USA; Department of Medicine, Harvard Medical School, Boston, MA 02115, USA.
Department of Molecular Oncology, Genentech, South San Francisco, CA 94080, USA.
Cell Stem Cell. 2020 Mar 5;26(3):391-402.e5. doi: 10.1016/j.stem.2020.01.008. Epub 2020 Feb 20.
Intestinal stem cells (ISCs) are confined to crypt bottoms and their progeny differentiate near crypt-villus junctions. Wnt and bone morphogenic protein (BMP) gradients drive this polarity, and colorectal cancer fundamentally reflects disruption of this homeostatic signaling. However, sub-epithelial sources of crucial agonists and antagonists that organize this BMP gradient remain obscure. Here, we couple whole-mount high-resolution microscopy with ensemble and single-cell RNA sequencing (RNA-seq) to identify three distinct PDGFRA mesenchymal cell types. PDGFRA(hi) telocytes are especially abundant at the villus base and provide a BMP reservoir, and we identified a CD81 PDGFRA(lo) population present just below crypts that secretes the BMP antagonist Gremlin1. These cells, referred to as trophocytes, are sufficient to expand ISCs in vitro without additional trophic support and contribute to ISC maintenance in vivo. This study reveals intestinal mesenchymal structure at fine anatomic, molecular, and functional detail and the cellular basis for a signaling gradient necessary for tissue self-renewal.
肠干细胞（ISCs）局限于隐窝底部，其后代在隐窝-绒毛交界处分化。Wnt 和骨形态发生蛋白（BMP）梯度驱动这种极性，结直肠癌从根本上反映了这种体内平衡信号的中断。然而，组织这种 BMP 梯度的关键激动剂和拮抗剂的上皮下来源仍然不清楚。在这里，我们将整体高分辨率显微镜与集落和单细胞 RNA 测序（RNA-seq）相结合，以鉴定三种不同的 PDGFRA 间充质细胞类型。PDGFRA(hi) 间质细胞在绒毛基部特别丰富，提供 BMP 储库，我们鉴定出一种存在于隐窝下方的 CD81 PDGFRA(lo) 群体，其分泌 BMP 拮抗剂 Gremlin1。这些细胞被称为滋养细胞，足以在没有额外营养支持的情况下在体外扩增 ISC，并有助于体内 ISC 的维持。这项研究揭示了肠道间充质组织在精细的解剖学、分子和功能细节以及组织自我更新所需的信号梯度的细胞基础。
