Integrin β6 in Macula Densa Contributes to Tubuloglomerular Crosstalk

Abstract of the paper:Integrin β6 activates transforming growth factor-β on tubular cells. <i>β6</i>^<em>-/-</em> mice are protected against tubulointerstitial fibrosis, but effects on glomerular injury are unclear. We studied effects of <i>β6</i>^<em>-/-</em>^{<em> </em>}in two kidney injury models. Non-hypertensive injury was induced in mice with a toxin receptor on podocytes (Nep25) with intact or knockout of <i>β6 </i>by aristolochic acid-induced tubular injury and toxin podocyte injury. <i>β6</i>^<em>-/-</em>/Nep25 mice had less interstitial fibrosis and glomerulosclerosis than Nep25 mice with intact β6. However, after hypertensive 5/6 nephrectomy (Nx), <i>β6</i>^<em>-/-</em>^{<em> </em>}mice had milder tubulointerstitial fibrosis but more glomerulosclerosis than wild type (WT). Key tubuloglomerular feedback (TGF) modulators, nNOS, COX-2, and renin, were similar in <i>β6</i>^<em>-/-</em>/Nep25 and Nep25 mice after nonhypertensive injury. After 5/6 Nx, nNOS was decreased and renin was increased in <i>β6</i>^<em>-/-</em> vs WT mice. GFR response to acute volume expansion, an indicator of classic TGF, was delayed in <i>β6</i>^<em>-/-</em>^{<em> </em>}mice vs WT. Adding high salt to the nonhypertensive model resulted in less hypertension and sodium excretion but higher GFR in <i>β6</i>^<em>-/-</em>/Nep25 vs Nep25 mice. High salt added to 5/6 Nx resulted in higher sodium excretion but lower GFR in <i>β6</i>^<em>-/-</em>^{<em> </em>}vs WT. In vitro, knockdown of β6 in macula densa cells increased Na⁺–K⁺–2Cl⁻ cotransporter and high salt altered TGF molecules in WT but not in β6 deficient cells. In conclusion, deletion of integrin β6 influences tubuloglomerular crosstalk by decreasing interstitial fibrosis and blunting TGF, with paradoxical increased glomerulosclerosis in hypertensive, but not in non-hypertensive conditions.This dataset contains detailed methods and original data relevant to the paper:A Word file providing comprehensive descriptions of animal models.An Excel file comprising all biological and molecular biology original analysis data from in vivo and in vitro studies.论文摘要：整合素β6（Integrin β6）可在肾小管细胞上激活转化生长因子-β（transforming growth factor-β, TGF-β）。β6基因敲除（β6^-/-）小鼠可抵抗肾小管间质纤维化，但该基因对肾小球损伤的影响尚不明确。本研究在两种肾脏损伤模型中探究了β6基因敲除的作用。本研究通过马兜铃酸诱导肾小管损伤、毒素诱导足细胞（podocytes）损伤，在携带足细胞特异性毒素受体（Nep25）且整合素β6基因完整或敲除的小鼠中构建非高血压性肾脏损伤模型。结果显示，β6^-/-/Nep25小鼠的间质纤维化与肾小球硬化（glomerulosclerosis）程度均低于β6基因完整的Nep25小鼠。然而，在高血压性5/6肾切除术（5/6 nephrectomy, 5/6 Nx）模型中，β6^-/-小鼠的肾小管间质纤维化程度较野生型（wild type, WT）更轻，但肾小球硬化程度更高。在非高血压性损伤后，β6^-/-/Nep25小鼠与野生型Nep25小鼠的关键管球反馈（tubuloglomerular feedback, TGF）调节因子——神经型一氧化氮合酶（neuronal nitric oxide synthase, nNOS）、环氧合酶2（cyclooxygenase 2, COX-2）与肾素（renin）的表达水平无显著差异。在5/6肾切除术后，β6^-/-小鼠的nNOS表达水平较野生型更低，而肾素水平更高。经典管球反馈的评价指标——急性容量扩张后的肾小球滤过率（glomerular filtration rate, GFR）响应在β6^-/-小鼠中较野生型小鼠出现延迟。在非高血压性模型中加入高盐干预后，β6^-/-/Nep25小鼠的高血压发生率与钠排泄量均低于Nep25小鼠，但肾小球滤过率更高。在5/6肾切除术模型中加入高盐干预后，β6^-/-小鼠的钠排泄量较野生型更高，但肾小球滤过率更低。体外（in vitro）实验中，在致密斑细胞（macula densa cells）中敲低（knockdown）β6基因可上调Na+-K+-2Cl-共转运体（Na+–K+–2Cl− cotransporter）的表达，而高盐干预仅在野生型细胞中改变了TGF相关分子的表达，在β6缺陷细胞中无此变化。综上，整合素β6基因缺失可通过减轻间质纤维化、削弱管球反馈信号影响管球串扰，在高血压性损伤条件下会导致肾小球硬化程度反常升高，但在非高血压性损伤条件下无此现象。本数据集包含与该论文相关的详细实验方法与原始数据：一份Word文档，全面详述了动物模型的构建与实验方案；一份Excel文件，涵盖了体内（in vivo）与体外生物学及分子生物学实验的全部原始分析数据。