The establishment of new animal models for diabetic nephropathy (DN) and the development of Midkine-targeted therapy against DN.

我们描述了两种有趣的糖尿病肾病小鼠模型的发病机制;即，1)中期因子（Mdk）+/+小鼠（129/SV背景）中链脲佐菌素（STZ）治疗的糖尿病模型，和2）β3细胞特异性钙调蛋白过表达小鼠（CaMTg小鼠）。首先，生长因子中期因子（Mdk-/-）缺陷的小鼠表现出显著较轻的肾病，即使Mdk-/-和+/+小鼠在STZ注射后表现出相似程度的高血糖。MK的表达在糖尿病肾病的Mdk+/+小鼠的肾小球系膜中被诱导，并且在暴露于高糖的原代培养的系膜细胞中被诱导。高糖负荷时，Mdk-/-系膜细胞蛋白激酶C和细胞外信号调节激酶磷酸化水平降低，转化生长因子β 1的产生减少。外源性MK可恢复高糖条件下Mdk-/-细胞中细胞外信号调节激酶的磷酸化，而MK反义寡核苷酸可抑制Mdk-/-细胞中细胞外信号调节激酶的磷酸化。 ...更多信息 +/+细胞。这表明MK加速了肾病中高血糖引起的细胞内信号网络。第二，CaMTg小鼠在3月龄及以后表现出明显的蛋白尿。在6月龄和9月龄的CaMTg小鼠中观察到结节性病变，甚至在9月龄的CaMTg小鼠中偶尔出现渗出性病变。在6个月和9个月大的CaMTg中观察到传入和传出小动脉的玻璃样变性。内皮型一氧化氮合酶（eNOS）的表达水平下降，VEGF，主要分布在足细胞，在3个月和6个月的CaMTg肾升高。VEGF受体（VEGFR）-1在6 M CaMTg肾中的表达低于nTg肾。对于VEGFR-2，未观察到CaMTg和nTg肾脏之间的这种差异。与nTg小鼠相比，6月龄和9月龄CaMTg小鼠的血栓调节蛋白阳性血管面积增加。这些发现表明CaMTg小鼠发生了人类糖尿病肾病的最典型的独特病变。VEGF水平升高、eNOS和VEGFR-1表达降低可能导致VEGFR-2信号通路的优先激活和内皮细胞的增殖，这些模型对研究糖尿病肾病的发病机制和开发新的治疗方法是非常有用的。少

We characterized the pathogenesis of two interesting mice models for diabetic nephropathy ; i.e., 1) Streptozotocin (STZ)-treated diabetic model in midkine (Mdk)+/+ mice (129/SV background), and 2) β3 cell-specific calmodulin overexpressing mice (CaMTg mice).First, mice deficient in the growth factor midkine (Mdk-/-) exhibited strikingly milder nephropathy, even though Mdk-/- and +/+ mice showed similar extents of hyperglycemia after STZ injection. MK expression was induced in the glomerular mesangium of Mdk+/+ mice with diabetic nephropathy, and in primary cultured mesangial cells exposed to high glucose. Mdk-/- mesangial cells exhibited reduced phosphorylation of protein kinase C and extracellular signal-regulated kinase, and reduced production of transforming growth factor-β_1 upon high glucose loading. Exogenous MK restored extracellular signal-regulated kinase phosphorylation in Mdk-/- cells under high glucose conditions, whereas a MK antisense oligonucleotide suppressed it in Mdk … More +/+ cells. This suggests that MK accelerates the intracellular signaling network evoked by hyperglycemia in nephropathy.Second, CaMTg mice showed evident albuminuria at 3 months of age and thereafter. Nodular lesions were seen in CaMTg mice at 6 and 9 months of age, and even exudative lesions occasionally appeared in 9 month-old CaMTg mice. Hyalinosis of the afferent and efferent arterioles was observed in 6- and 9-month-old CaMTg. The expression level of endothelial nitric oxidase synthase (eNOS) was decreased and that of VEGF, mainly distributed in the podocytes, was elevated in the 3- and 6-month-old CaMTg kidney. VEGF receptor (VEGFR)-1 was less expressed in the 6M CaMTg kidney than nTg one. Such difference between the CaMTg and nTg kidneys was not seen for VEGFR-2. There was an increase of the thrombomodulin-positive vascular area in the 6- and 9-month-old CaMTg mice compared to the nTg ones. These findings indicate CaMTg mice developed most typical distinct lesions of human diabetic nephropathy. The elevated VEGF level and diminished eNOS and VEGFR-1 expression may result in preferential activation of the VEGFR-2 signaling and eventual proliferation of the endotherial cells.We propose these models are very useful for investigations of the pathogenesis of diabetic nephropathy and for the development of new treatments. Less