From Hubrecht Institute, KNAW (G.P.A.L., J.P.J., M.M.G., B.M., K.T.S., M.V.-G., D.V., H.d.R., M.W.V., M.P.C., A.v.O., E.v.R.), Department of Pathology (M.M.H.H.), Department of Cardiology (N.d.J., E.v.R.), University Medical Center Utrecht, The Netherlands; and Berlin Institute for Medical Systems Biology, Max Delbrück Center for Molecular Medicine, Berlin, Germany (J.P.J.).
Circulation. 2017 Oct 10;136(15):1396-1409. doi: 10.1161/CIRCULATIONAHA.117.027832. Epub 2017 Jul 19.
Cardiac ischemic injury induces a pathological remodeling response, which can ultimately lead to heart failure. Detailed mechanistic insights into molecular signaling pathways relevant for different aspects of cardiac remodeling will support the identification of novel therapeutic targets.
Although genome-wide transcriptome analysis on diseased tissues has greatly advanced our understanding of the regulatory networks that drive pathological changes in the heart, this approach has been disadvantaged by the fact that the signals are derived from tissue homogenates. Here we used tomo-seq to obtain a genome-wide gene expression signature with high spatial resolution spanning from the infarcted area to the remote to identify new regulators of cardiac remodeling. Cardiac tissue samples from patients suffering from ischemic heart disease were used to validate our findings.
Tracing transcriptional differences with a high spatial resolution across the infarcted heart enabled us to identify gene clusters that share a comparable expression profile. The spatial distribution patterns indicated a separation of expressional changes for genes involved in specific aspects of cardiac remodeling, such as fibrosis, cardiomyocyte hypertrophy, and calcium handling (, , and ). Subsequent correlation analysis allowed for the identification of novel factors that share a comparable transcriptional regulation pattern across the infarcted tissue. The strong correlation between the expression levels of these known marker genes and the expression of the coregulated genes could be confirmed in human ischemic cardiac tissue samples. Follow-up analysis identified SOX9 as common transcriptional regulator of a large portion of the fibrosis-related genes that become activated under conditions of ischemic injury. Lineage-tracing experiments indicated that the majority of COL1-positive fibroblasts stem from a pool of SOX9-expressing cells, and in vivo loss of blunted the cardiac fibrotic response on ischemic injury. The colocalization between SOX9 and COL1 could also be confirmed in patients suffering from ischemic heart disease.
Based on the exact local expression cues, tomo-seq can serve to reveal novel genes and key transcription factors involved in specific aspects of cardiac remodeling. Using tomo-seq, we were able to unveil the unknown relevance of SOX9 as a key regulator of cardiac fibrosis, pointing to SOX9 as a potential therapeutic target for cardiac fibrosis.
心脏缺血性损伤会引起病理性重构反应，最终导致心力衰竭。深入了解与心脏重构不同方面相关的分子信号通路的机制见解将有助于确定新的治疗靶点。
尽管对病变组织进行全基因组转录组分析极大地促进了我们对驱动心脏发生病理变化的调控网络的理解，但这种方法的缺点是信号来源于组织匀浆。在这里，我们使用 tomoseq 来获得具有高空间分辨率的全基因组基因表达特征，该特征跨越从梗塞区域到远程区域，以识别心脏重构的新调节剂。使用来自患有缺血性心脏病的患者的心脏组织样本验证了我们的发现。
通过在整个梗塞心脏上进行高空间分辨率的转录差异追踪，我们能够识别具有相似表达谱的基因簇。空间分布模式表明，参与心脏重构特定方面（如纤维化、心肌细胞肥大和钙处理）的基因的表达变化分离（[文献 1]、[文献 2]和[文献 3]）。随后的相关分析允许识别在整个梗塞组织中具有相似转录调控模式的新因子。这些已知标记基因的表达水平与核心调节基因的表达之间的强相关性可以在人类缺血性心脏组织样本中得到证实。后续分析确定 SOX9 为在缺血性损伤条件下激活的大部分纤维化相关基因的共同转录调节因子。谱系追踪实验表明，大多数 COL1 阳性成纤维细胞源自 SOX9 表达细胞的池，体内缺失[文献 4]减弱了缺血性损伤后的心脏纤维化反应。在患有缺血性心脏病的患者中也可以证实 SOX9 与 COL1 之间的共定位。
基于确切的局部表达线索，tomo-seq 可用于揭示参与心脏重构特定方面的新基因和关键转录因子。使用 tomo-seq，我们能够揭示 SOX9 作为心脏纤维化关键调节因子的未知相关性，表明 SOX9 可能是心脏纤维化的潜在治疗靶点。
