Matkovich Scot J, Grubb David R, McMullen Julie R, Woodcock Elizabeth A
Center for Pharmacogenomics, Department of Internal Medicine, Washington University School of Medicine, St. Louis, MO, United States of America.
Baker IDI Heart and Diabetes Institute, Melbourne, Australia.
PLoS One. 2016 Jun 30;11(6):e0158317. doi: 10.1371/journal.pone.0158317. eCollection 2016.
Diseased myocardium from humans and experimental animal models shows heightened expression and activity of a specific subtype of phospholipase C (PLC), the splice variant PLCβ1b. Previous studies from our group showed that increasing PLCβ1b expression in adult mouse hearts by viral transduction was sufficient to cause sustained contractile dysfunction of rapid onset, which was maintained indefinitely in the absence of other pathological changes in the myocardium. We hypothesized that impaired contractility alone would be sufficient to induce a compensatory transcriptional response. Unbiased, comprehensive mRNA-sequencing was performed on 6 biological replicates of rAAV6-treated blank, PLCβ1b and PLCβ1a (closely related but inactive splice variant) hearts 8 weeks after injection, when reduced contractility was manifest in PLCβ1b hearts without evidence of induced hypertrophy. Expression of PLCβ1b resulted in expression changes in only 9 genes at FDR<0.1 when compared with control and these genes appeared unrelated to contractility. Importantly, PLCβ1a caused similar mild expression changes to PLCβ1b, despite a complete lack of effect of this isoform on cardiac contractility. We conclude that contractile depression caused by PLCβ1b activation is largely independent of changes in the transcriptome, and thus that lowered contractility is not sufficient in itself to provoke measurable transcriptomic alterations. In addition, our data stress the importance of a stringent control group to filter out transcriptional changes unrelated to cardiac function.
来自人类和实验动物模型的患病心肌显示出磷脂酶C（PLC）的一种特定亚型即剪接变体PLCβ1b的表达和活性增强。我们团队之前的研究表明，通过病毒转导增加成年小鼠心脏中PLCβ1b的表达足以导致快速发作的持续性收缩功能障碍，在心肌没有其他病理变化的情况下，这种功能障碍会无限期持续。我们假设仅收缩功能受损就足以诱导代偿性转录反应。在注射8周后，对经rAAV6处理的空白、PLCβ1b和PLCβ1a（密切相关但无活性的剪接变体）心脏的6个生物学重复样本进行了无偏倚、全面的mRNA测序，此时PLCβ1b心脏出现收缩力下降，但无诱导性肥大的证据。与对照组相比，PLCβ1b的表达仅导致9个基因在FDR<0.1时有表达变化，且这些基因似乎与收缩力无关。重要的是，尽管PLCβ1a对心脏收缩力完全没有影响，但它引起的表达变化与PLCβ1b相似且程度较轻。我们得出结论，由PLCβ1b激活引起的收缩功能抑制在很大程度上独立于转录组的变化，因此收缩力降低本身不足以引发可测量的转录组改变。此外，我们的数据强调了严格对照组对于筛选出与心脏功能无关的转录变化的重要性。
