Preferential expression of insulin-like growth factor binding proteins-1, -3, and -5 during early diabetic renal hypertrophy in rats

The renal insulin-like growth factor-I (IGF-I) system has been implicated in the pathogenesis of renal hypertrophy, altered hemodynamics, and extracellular matrix expansion associated with early diabetes. The relative abundance of IGF binding proteins (IGFBPs) in the renal microenvironment may modulate IGF-I actions. However, the precise IGFBPs expressed in the glomerular and tubulointerstitial compartments during diabetic renal growth have not been characterized. In the present study, in situ hybridization studies were performed to examine the expression of IGFBP-1 to -6 messenger RNAs (mRNAs) 3, 7, and 14 days after streptozotocin (STZ) injection in rats. In control, nondiabetic kidneys, all six IGFBP mRNAs were differentially expressed with a predominance of IGFBP-5. The onset of renal hypertrophy in STZ-induced diabetes was associated with a rapid and site-specific induction of IGFBP-1, -3, and -5 mRNAs. In contrast, basal expression of IGFBP-2, -4, and -6 mRNAs was not altered in diabetic rats. IGFBP-5 mRNA expression increased in diabetic glomeruli, cortical, and inner medullary peritubular interstitial cells at days 3, 7, and 14. Although normal glomeruli failed to express IGFBP-3, it was induced concomitantly with IGFBP-5 in diabetic glomeruli and cortical peritubular interstitial cells. IGFBP-1 mRNA levels also increased in cortical tubular cells at each time point tested. Peak induction of IGFBP-3 and -5 was observed at day 3, whereas IGFBP-1 was delayed until day 7. IGFBP-1, -3, and -5 mRNA levels declined by day 14, but remained persistently elevated above control. By immunoperoxidase staining, similar alterations in the pattern of IGFBP-3 and -5 protein expression were observed at each time point. The preferential and site-specific increase in IGFBP-1, -3, and -5 suggest that these IGFBPs may regulate the local autocrine and/or paracrine actions of IGF-I and contribute to the pathogenesis of the early manifestations of diabetic nephropathy.     

Glomerulosclerosis in mice transgenic for human insulin-like growth factor-binding protein-1

BACKGROUND: The growth hormone (GH)/insulin-like growth factor (IGF) system is thought to participate in the glomerulosclerosis process. Because IGF-binding proteins (IGFBPs) modulate IGF actions and hence GH secretion, this study assessed whether mice transgenic for human IGFBP-1 have altered susceptibility to glomerulosclerosis. METHODS: A line of transgenic mice that express human IGFBP-1 mRNA in the liver under the control of the alpha1-antitrypsin promoter has been obtained, and morphological changes in the kidney tissue were assessed. Glomerulosclerosis was identified using light microscopy, light microscopic morphometry, and electron microscopy. Extracellular matrix components were analyzed by immunohistochemistry. RESULTS: There was a marked increase in mesangial extracellular matrix area in homozygous transgenic mice at three months of age as compared with heterozygous transgenic mice and nontransgenic littermates. These changes were not associated with alterations in glomerular volume or cellularity. The expansion of extracellular matrix area was related to a marked increase in laminin and type IV collagen and to the appearance of type I collagen. CONCLUSIONS: These observations indicate that the enhanced expression of IGFBP-1 may result in the development of glomerulosclerosis without glomerular hypertrophy. The changes are potentially related to a decrease in IGF-I availability and/or to an IGF-I-independent role of IGFBP-1.     

胰岛素和胰岛素样生长因子及其结合蛋白与结直肠癌发生的关系

目的 探讨血清胰岛素、胰岛素样生长因子(IGF-1)、IGF结合蛋白(IGFBPs)及体质量指数(BMI)、腰臀围比(WHR)的变化及与结直肠癌发生、发展的关系.方法 检测对象为2006年6月至2007年10月间住院收治和门诊复查的结直肠癌患者615例(术前检测244例,术后371例)和健康对照者150例.采用酶联免疫吸附法检测血清胰岛素、IGF-1和IGFBPS水平.结果 结直肠癌患者术前血清胰岛素、IGF-1水平和IGF-Ⅰ/IGFBP-3比值与健康对照组、术后患者比较,均明显升高,IGFBP-3水平明显降低,差异均有统计学意义(P<0.05,P<0.01).结直肠癌术后未发生转移者与有肝或腹腔远处转移者胰岛素、IGF-1、IGFBP-1、IGFBP-3、IGF-1/IGFBP-3比较.差异均无统计学意义(P>0.05).结直肠癌患者WHR明显高于健康对照组(P<0.01和P<0.05):而BMI与健康对照组比较,差异无统计学意义(P>0.05).结肠癌患者WHR、BMI与胰岛素水平、IGF-1/IGFBP-3比值呈正相关(P<0.01,P<0.05),与IGFBP-3呈负相关(P<0.01,P<0.05);直肠癌患者WHR与血清瘦素、胰岛素水平及BMI与血清IGFBP-1水平均呈正相关(P<0.05),与其他无相关性(P>0.05).结论 胰岛素、IGF-1水平和IGF-Ⅰ/IGFBP-3比值升高及IGFBP-3水平降低,可能与结直肠癌的发生有关,但与肿瘤转移与否无关,中心性肥胖是结肠癌发生的危险因素之一.     

胰岛素和胰岛素样生长因子及其结合蛋白与结直肠癌发生的关系

目的 探讨血清胰岛素、胰岛素样生长因子(IGF-1)、IGF结合蛋白(IGFBPs)及体质量指数(BMI)、腰臀围比(WHR)的变化及与结直肠癌发生、发展的关系.方法 检测对象为2006年6月至2007年10月间住院收治和门诊复查的结直肠癌患者615例(术前检测244例,术后371例)和健康对照者150例.采用酶联免疫吸附法检测血清胰岛素、IGF-1和IGFBPS水平.结果 结直肠癌患者术前血清胰岛素、IGF-1水平和IGF-Ⅰ/IGFBP-3比值与健康对照组、术后患者比较,均明显升高,IGFBP-3水平明显降低,差异均有统计学意义(P<0.05,P<0.01).结直肠癌术后未发生转移者与有肝或腹腔远处转移者胰岛素、IGF-1、IGFBP-1、IGFBP-3、IGF-1/IGFBP-3比较.差异均无统计学意义(P>0.05).结直肠癌患者WHR明显高于健康对照组(P<0.01和P<0.05):而BMI与健康对照组比较,差异无统计学意义(P>0.05).结肠癌患者WHR、BMI与胰岛素水平、IGF-1/IGFBP-3比值呈正相关(P<0.01,P<0.05),与IGFBP-3呈负相关(P<0.01,P<0.05);直肠癌患者WHR与血清瘦素、胰岛素水平及BMI与血清IGFBP-1水平均呈正相关(P<0.05),与其他无相关性(P>0.05).结论 胰岛素、IGF-1水平和IGF-Ⅰ/IGFBP-3比值升高及IGFBP-3水平降低,可能与结直肠癌的发生有关,但与肿瘤转移与否无关,中心性肥胖是结肠癌发生的危险因素之一.     

胰岛素和胰岛素样生长因子及其结合蛋白与结直肠癌发生的关系

目的 探讨血清胰岛素、胰岛素样生长因子(IGF-1)、IGF结合蛋白(IGFBPs)及体质量指数(BMI)、腰臀围比(WHR)的变化及与结直肠癌发生、发展的关系.方法 检测对象为2006年6月至2007年10月间住院收治和门诊复查的结直肠癌患者615例(术前检测244例,术后371例)和健康对照者150例.采用酶联免疫吸附法检测血清胰岛素、IGF-1和IGFBPS水平.结果 结直肠癌患者术前血清胰岛素、IGF-1水平和IGF-Ⅰ/IGFBP-3比值与健康对照组、术后患者比较,均明显升高,IGFBP-3水平明显降低,差异均有统计学意义(P<0.05,P<0.01).结直肠癌术后未发生转移者与有肝或腹腔远处转移者胰岛素、IGF-1、IGFBP-1、IGFBP-3、IGF-1/IGFBP-3比较.差异均无统计学意义(P>0.05).结直肠癌患者WHR明显高于健康对照组(P<0.01和P<0.05):而BMI与健康对照组比较,差异无统计学意义(P>0.05).结肠癌患者WHR、BMI与胰岛素水平、IGF-1/IGFBP-3比值呈正相关(P<0.01,P<0.05),与IGFBP-3呈负相关(P<0.01,P<0.05);直肠癌患者WHR与血清瘦素、胰岛素水平及BMI与血清IGFBP-1水平均呈正相关(P<0.05),与其他无相关性(P>0.05).结论 胰岛素、IGF-1水平和IGF-Ⅰ/IGFBP-3比值升高及IGFBP-3水平降低,可能与结直肠癌的发生有关,但与肿瘤转移与否无关,中心性肥胖是结肠癌发生的危险因素之一.     

胰岛素和胰岛素样生长因子及其结合蛋白与结直肠癌发生的关系

目的探讨血清胰岛素、胰岛素样生长因子（IGF-1）、IGF结合蛋白（IGFBPs）体质量指数（BMI）、腰臀围比（WHR）的变化及与结直肠癌发生、发展的关系。方法检测对象为2006年6月至2007年10月间住院收治和门诊复查的结直肠癌患者615例（术前检测244例,术后371例）和健康对照者150例。采用酶联免疫吸附法检测血清胰岛素、IGF-1和IGFBPS水平。结果结直肠癌患者术前血清胰岛素、IGF-1水平和IGF-I／IGFBP-3比值与健康对照组、术后患者比较,均明显升高,IGFBP-3水平明显降低,差异均有统计学意义（P〈0.05,P〈0.01）。结直肠癌术后未发生转移者与有肝或腹腔远处转移者胰岛素、IGF-1、IGFBP-1、IGFBP-3、IGF-1／IGFBP-3比较,差异均无统计学意义（P〉0.05）。结直肠癌患者WHR明显高于健康对照组（P〈0.01和P〈0.05）;而BMI与健康对照组比较,差异无统计学意义（P〉0.05）。结肠癌患者WHR、BMI与胰岛素水平、IGF-1／IGFBP-3比值呈正相关（P〈0.01,P〈0.05）,与IGFBP-3呈负相关（P〈0.01,P〈0.05）;直肠癌患者WHR与血清瘦素、胰岛素水平及BMI与血清IGFBP-1水平均呈正相关（P〈0.05）,与其他无相关性（P〉0.05）。结论胰岛素、IGF-1水平和IGF-I／IGFBP-3比值升高及IGFBP-3水平降低,可能与结直肠癌的发生有关,但与肿瘤转移与否无关,中心性肥胖是结肠癌发生的危险因素之一。     

胰岛素和胰岛素样生长因子及其结合蛋白与结直肠癌发生的关系

目的 探讨血清胰岛素、胰岛素样生长因子(IGF-1)、IGF结合蛋白(IGFBPs)及体质量指数(BMI)、腰臀围比(WHR)的变化及与结直肠癌发生、发展的关系.方法 检测对象为2006年6月至2007年10月间住院收治和门诊复查的结直肠癌患者615例(术前检测244例,术后371例)和健康对照者150例.采用酶联免疫吸附法检测血清胰岛素、IGF-1和IGFBPS水平.结果 结直肠癌患者术前血清胰岛素、IGF-1水平和IGF-Ⅰ/IGFBP-3比值与健康对照组、术后患者比较,均明显升高,IGFBP-3水平明显降低,差异均有统计学意义(P<0.05,P<0.01).结直肠癌术后未发生转移者与有肝或腹腔远处转移者胰岛素、IGF-1、IGFBP-1、IGFBP-3、IGF-1/IGFBP-3比较.差异均无统计学意义(P>0.05).结直肠癌患者WHR明显高于健康对照组(P<0.01和P<0.05):而BMI与健康对照组比较,差异无统计学意义(P>0.05).结肠癌患者WHR、BMI与胰岛素水平、IGF-1/IGFBP-3比值呈正相关(P<0.01,P<0.05),与IGFBP-3呈负相关(P<0.01,P<0.05);直肠癌患者WHR与血清瘦素、胰岛素水平及BMI与血清IGFBP-1水平均呈正相关(P<0.05),与其他无相关性(P>0.05).结论 胰岛素、IGF-1水平和IGF-Ⅰ/IGFBP-3比值升高及IGFBP-3水平降低,可能与结直肠癌的发生有关,但与肿瘤转移与否无关,中心性肥胖是结肠癌发生的危险因素之一.     

胰岛素和胰岛素样生长因子及其结合蛋白与结直肠癌发生的关系

目的 探讨血清胰岛素、胰岛素样生长因子(IGF-1)、IGF结合蛋白(IGFBPs)及体质量指数(BMI)、腰臀围比(WHR)的变化及与结直肠癌发生、发展的关系.方法 检测对象为2006年6月至2007年10月间住院收治和门诊复查的结直肠癌患者615例(术前检测244例,术后371例)和健康对照者150例.采用酶联免疫吸附法检测血清胰岛素、IGF-1和IGFBPS水平.结果 结直肠癌患者术前血清胰岛素、IGF-1水平和IGF-Ⅰ/IGFBP-3比值与健康对照组、术后患者比较,均明显升高,IGFBP-3水平明显降低,差异均有统计学意义(P<0.05,P<0.01).结直肠癌术后未发生转移者与有肝或腹腔远处转移者胰岛素、IGF-1、IGFBP-1、IGFBP-3、IGF-1/IGFBP-3比较.差异均无统计学意义(P>0.05).结直肠癌患者WHR明显高于健康对照组(P<0.01和P<0.05):而BMI与健康对照组比较,差异无统计学意义(P>0.05).结肠癌患者WHR、BMI与胰岛素水平、IGF-1/IGFBP-3比值呈正相关(P<0.01,P<0.05),与IGFBP-3呈负相关(P<0.01,P<0.05);直肠癌患者WHR与血清瘦素、胰岛素水平及BMI与血清IGFBP-1水平均呈正相关(P<0.05),与其他无相关性(P>0.05).结论 胰岛素、IGF-1水平和IGF-Ⅰ/IGFBP-3比值升高及IGFBP-3水平降低,可能与结直肠癌的发生有关,但与肿瘤转移与否无关,中心性肥胖是结肠癌发生的危险因素之一.     

胰岛素和胰岛素样生长因子及其结合蛋白与结直肠癌发生的关系

目的 探讨血清胰岛素、胰岛素样生长因子(IGF-1)、IGF结合蛋白(IGFBPs)及体质量指数(BMI)、腰臀围比(WHR)的变化及与结直肠癌发生、发展的关系.方法 检测对象为2006年6月至2007年10月间住院收治和门诊复查的结直肠癌患者615例(术前检测244例,术后371例)和健康对照者150例.采用酶联免疫吸附法检测血清胰岛素、IGF-1和IGFBPS水平.结果 结直肠癌患者术前血清胰岛素、IGF-1水平和IGF-Ⅰ/IGFBP-3比值与健康对照组、术后患者比较,均明显升高,IGFBP-3水平明显降低,差异均有统计学意义(P<0.05,P<0.01).结直肠癌术后未发生转移者与有肝或腹腔远处转移者胰岛素、IGF-1、IGFBP-1、IGFBP-3、IGF-1/IGFBP-3比较.差异均无统计学意义(P>0.05).结直肠癌患者WHR明显高于健康对照组(P<0.01和P<0.05):而BMI与健康对照组比较,差异无统计学意义(P>0.05).结肠癌患者WHR、BMI与胰岛素水平、IGF-1/IGFBP-3比值呈正相关(P<0.01,P<0.05),与IGFBP-3呈负相关(P<0.01,P<0.05);直肠癌患者WHR与血清瘦素、胰岛素水平及BMI与血清IGFBP-1水平均呈正相关(P<0.05),与其他无相关性(P>0.05).结论 胰岛素、IGF-1水平和IGF-Ⅰ/IGFBP-3比值升高及IGFBP-3水平降低,可能与结直肠癌的发生有关,但与肿瘤转移与否无关,中心性肥胖是结肠癌发生的危险因素之一.     

胰岛素和胰岛素样生长因子及其结合蛋白与结直肠癌发生的关系

目的 探讨血清胰岛素、胰岛素样生长因子(IGF-1)、IGF结合蛋白(IGFBPs)及体质量指数(BMI)、腰臀围比(WHR)的变化及与结直肠癌发生、发展的关系.方法 检测对象为2006年6月至2007年10月间住院收治和门诊复查的结直肠癌患者615例(术前检测244例,术后371例)和健康对照者150例.采用酶联免疫吸附法检测血清胰岛素、IGF-1和IGFBPS水平.结果 结直肠癌患者术前血清胰岛素、IGF-1水平和IGF-Ⅰ/IGFBP-3比值与健康对照组、术后患者比较,均明显升高,IGFBP-3水平明显降低,差异均有统计学意义(P<0.05,P<0.01).结直肠癌术后未发生转移者与有肝或腹腔远处转移者胰岛素、IGF-1、IGFBP-1、IGFBP-3、IGF-1/IGFBP-3比较.差异均无统计学意义(P>0.05).结直肠癌患者WHR明显高于健康对照组(P<0.01和P<0.05):而BMI与健康对照组比较,差异无统计学意义(P>0.05).结肠癌患者WHR、BMI与胰岛素水平、IGF-1/IGFBP-3比值呈正相关(P<0.01,P<0.05),与IGFBP-3呈负相关(P<0.01,P<0.05);直肠癌患者WHR与血清瘦素、胰岛素水平及BMI与血清IGFBP-1水平均呈正相关(P<0.05),与其他无相关性(P>0.05).结论 胰岛素、IGF-1水平和IGF-Ⅰ/IGFBP-3比值升高及IGFBP-3水平降低,可能与结直肠癌的发生有关,但与肿瘤转移与否无关,中心性肥胖是结肠癌发生的危险因素之一.     

胰岛素和胰岛素样生长因子及其结合蛋白与结直肠癌发生的关系

目的 探讨血清胰岛素、胰岛素样生长因子(IGF-1)、IGF结合蛋白(IGFBPs)及体质量指数(BMI)、腰臀围比(WHR)的变化及与结直肠癌发生、发展的关系.方法 检测对象为2006年6月至2007年10月间住院收治和门诊复查的结直肠癌患者615例(术前检测244例,术后371例)和健康对照者150例.采用酶联免疫吸附法检测血清胰岛素、IGF-1和IGFBPS水平.结果 结直肠癌患者术前血清胰岛素、IGF-1水平和IGF-Ⅰ/IGFBP-3比值与健康对照组、术后患者比较,均明显升高,IGFBP-3水平明显降低,差异均有统计学意义(P<0.05,P<0.01).结直肠癌术后未发生转移者与有肝或腹腔远处转移者胰岛素、IGF-1、IGFBP-1、IGFBP-3、IGF-1/IGFBP-3比较.差异均无统计学意义(P>0.05).结直肠癌患者WHR明显高于健康对照组(P<0.01和P<0.05):而BMI与健康对照组比较,差异无统计学意义(P>0.05).结肠癌患者WHR、BMI与胰岛素水平、IGF-1/IGFBP-3比值呈正相关(P<0.01,P<0.05),与IGFBP-3呈负相关(P<0.01,P<0.05);直肠癌患者WHR与血清瘦素、胰岛素水平及BMI与血清IGFBP-1水平均呈正相关(P<0.05),与其他无相关性(P>0.05).结论 胰岛素、IGF-1水平和IGF-Ⅰ/IGFBP-3比值升高及IGFBP-3水平降低,可能与结直肠癌的发生有关,但与肿瘤转移与否无关,中心性肥胖是结肠癌发生的危险因素之一.     

胰岛素和胰岛素样生长因子及其结合蛋白与结直肠癌发生的关系

目的 探讨血清胰岛素、胰岛素样生长因子(IGF-1)、IGF结合蛋白(IGFBPs)及体质量指数(BMI)、腰臀围比(WHR)的变化及与结直肠癌发生、发展的关系.方法 检测对象为2006年6月至2007年10月间住院收治和门诊复查的结直肠癌患者615例(术前检测244例,术后371例)和健康对照者150例.采用酶联免疫吸附法检测血清胰岛素、IGF-1和IGFBPS水平.结果 结直肠癌患者术前血清胰岛素、IGF-1水平和IGF-Ⅰ/IGFBP-3比值与健康对照组、术后患者比较,均明显升高,IGFBP-3水平明显降低,差异均有统计学意义(P<0.05,P<0.01).结直肠癌术后未发生转移者与有肝或腹腔远处转移者胰岛素、IGF-1、IGFBP-1、IGFBP-3、IGF-1/IGFBP-3比较.差异均无统计学意义(P>0.05).结直肠癌患者WHR明显高于健康对照组(P<0.01和P<0.05):而BMI与健康对照组比较,差异无统计学意义(P>0.05).结肠癌患者WHR、BMI与胰岛素水平、IGF-1/IGFBP-3比值呈正相关(P<0.01,P<0.05),与IGFBP-3呈负相关(P<0.01,P<0.05);直肠癌患者WHR与血清瘦素、胰岛素水平及BMI与血清IGFBP-1水平均呈正相关(P<0.05),与其他无相关性(P>0.05).结论 胰岛素、IGF-1水平和IGF-Ⅰ/IGFBP-3比值升高及IGFBP-3水平降低,可能与结直肠癌的发生有关,但与肿瘤转移与否无关,中心性肥胖是结肠癌发生的危险因素之一.     

胰岛素和胰岛素样生长因子及其结合蛋白与结直肠癌发生的关系

目的 探讨血清胰岛素、胰岛素样生长因子(IGF-1)、IGF结合蛋白(IGFBPs)及体质量指数(BMI)、腰臀围比(WHR)的变化及与结直肠癌发生、发展的关系.方法 检测对象为2006年6月至2007年10月间住院收治和门诊复查的结直肠癌患者615例(术前检测244例,术后371例)和健康对照者150例.采用酶联免疫吸附法检测血清胰岛素、IGF-1和IGFBPS水平.结果 结直肠癌患者术前血清胰岛素、IGF-1水平和IGF-Ⅰ/IGFBP-3比值与健康对照组、术后患者比较,均明显升高,IGFBP-3水平明显降低,差异均有统计学意义(P<0.05,P<0.01).结直肠癌术后未发生转移者与有肝或腹腔远处转移者胰岛素、IGF-1、IGFBP-1、IGFBP-3、IGF-1/IGFBP-3比较.差异均无统计学意义(P>0.05).结直肠癌患者WHR明显高于健康对照组(P<0.01和P<0.05):而BMI与健康对照组比较,差异无统计学意义(P>0.05).结肠癌患者WHR、BMI与胰岛素水平、IGF-1/IGFBP-3比值呈正相关(P<0.01,P<0.05),与IGFBP-3呈负相关(P<0.01,P<0.05);直肠癌患者WHR与血清瘦素、胰岛素水平及BMI与血清IGFBP-1水平均呈正相关(P<0.05),与其他无相关性(P>0.05).结论 胰岛素、IGF-1水平和IGF-Ⅰ/IGFBP-3比值升高及IGFBP-3水平降低,可能与结直肠癌的发生有关,但与肿瘤转移与否无关,中心性肥胖是结肠癌发生的危险因素之一.     

Physiological differences in insulin-like growth factor binding protein-1 (IGFBP-1) phosphorylation in IGFBP-1 transgenic mice

Insulin-like growth factor binding protein (IGFBP)-1 has been shown to alter cellular responses to insulin-like growth factor 1 (IGF-1). Human IGFBP-1 undergoes serine phosphorylation, and this enhances both its affinity for IGF-1 by six- to eightfold and its capacity to inhibit IGF-1 actions. To investigate the physiological role of IGFBP-1 in vivo, transgenic mice have been generated using either the human IGFBP-1 or rat IGFBP-1 transgene. Both lines of mice expressed high concentrations of IGFBP-1 in serum and tissues; however, human IGFBP-1 transgenic mice did not show glucose intolerance and exhibited no significant intrauterine growth retardation, whereas rat IGFBP-1 transgenic mice showed fasting hyperglycemia and intrauterine growth restriction. The aim of this study was to investigate the physiological differences in the phosphorylation state of human IGFBP-1 and rat IGFBP-1 in these transgenic mice. The phosphorylation status of IGFBP-1 in transgenic mouse serum was analyzed by nondenaturing PAGE. Almost all of the IGFBP-1 in serum from the human IGFBP-1 transgenic mice was present as a nonphosphorylated form. Most of the rat IGFBP-1 in the serum of the mice expressing the rat IGFBP-1 was phosphorylated. Immunoprecipitation showed that mouse hepatoma (Hepa 1-6) cells (exposed to [32P]H3PO4) secrete 32P-labeled IGFBP-1. When the human IGFBP-1 transgene was transfected into Hepa 1-6 cells, all of the IGFBP-1 was secreted in the nonphosphorylated form. However, when the rat IGFBP-1 transgene was transfected into these cells, phosphorylated forms of IGFBP-1 were secreted. To confirm this result, the mouse hepatoma cell protein kinase was partially purified. This kinase activity phosphorylated mouse and rat IGFBP-1 in vitro, but it did not phosphorylate human IGFBP-1. Scatchard analysis showed that the affinity of phosphorylated rat IGFBP-1 for IGF-1 was 3.9-fold higher than that of nonphosphorylated human IGFBP-1. We conclude that the mouse IGFBP-1 kinase activity cannot phosphorylate human IGFBP-1, whereas it can phosphorylate rat IGFBP-1. The phosphorylation state of human IGFBP-1 may account for part of the phenotypic differences noted in the two studies of transgenic mice, and it is an important determinant of the capacity of human IGFBP-1 to inhibit IGF-1 actions in vivo.     

Fibronectin fragments upregulate insulin-like growth factor binding proteins in chondrocytes

Addition of fibronectin fragments (Fn-fs) to cultured cartilage explants has been shown to mediate extensive cartilage matrix degradation followed by anabolic responses. OBJECTIVE: To determine whether specific Fn-fs regulate cartilage metabolism through a mechanism, in part, involving insulin-like growth factor (IGF) and insulin-like growth factor binding proteins (IGFBPs). METHODS: Primary bovine articular chondrocyte cultures were treated with Fn-fs. mRNA from the cultures was analysed by Northern blotting. Changes in the levels of IGFBPs in cellular extracts and conditioned media were analysed by Western ligand blotting. Explant cultures of bovine articular cartilage were used to assay release of exogenous IGF-I and IGFBP-2. An analog of IGF-I with altered affinity for IGFBPs was used to assay the effect of IGFBPs on proteoglycan synthesis. RESULTS: The Fn-fs increased protein levels of IGFBPs-2, -3 and -5 in conditioned media and of IGFBP-2 in cell extracts by as much as nine-fold. Conversely, the protein level of constitutively expressed IGBP-4 was decreased in conditioned medium. Northern blot analysis reflected increased IGFBP-3 mRNA but not decreased IGFBP-4 mRNA. The IGF-I analog was more effective at restoring PG synthesis suppression by Fn-fs than was wild type IGF-I. CONCLUSIONS: The Fn-fs increased levels of IGFBPs in cultures of bovine articular chondrocytes and elicited release of IGFBP-2 and IGF-I from articular cartilage. The increased level of IGFBPs may trap IGF-I and account in part for the initial suppression of PG synthesis. Induced proteinases may subsequently liberate IGF-I and cause greatly enhanced anabolic processes, contributing to cartilage repair.     

不同类型老年女性髋部骨折血清IGF-1及IGFBP-3,4,5表达相关性研究

目的研究不同类型老年女性髋部骨折中外周血清中血清胰岛素样生长因子1（IGF-1）及血清胰岛素样生长因子结合蛋白3,4,5（IGFBP-3,4,5）表达差异及同骨密度的相关性。方法选取年龄大于65岁老年女性髋部骨折患者,检测并比较外周血清中IGF-1及IGFBP-3,4,5表达差异及同骨密度的相关性。结果转子间骨折组转子区骨矿物质密度（BMD）较股骨颈骨折组低（P〈0.001）,股骨颈组血清中IGFBP-4含量较转子间骨折组低（P〈0.001）,而IGFBP-5含量高于转子间骨折组（P〈0.001）。在血清指标相关性表达中,血清IGF-1表达与股骨颈区BMD成正相关（R=0.46,P=0.002）,血清IGFBP-4同转子区BMD成负相关（R=-0.634,P〈0.001）,血清IGFBP-5同股骨颈区BMD成正相关（R=0.235,P〈0.001）。结论外周血清中IGF-1及其结合蛋白表达的差异可能是导致不同类型老年髋部骨折的病理机制之一,但由于IGF-1及其结合蛋白调节机制相当复杂,对于IGF-1及IGFBPs表达机制同骨折类型的关系尚需大量的实验研究进一步证实。     

The role of adrenomedullin and receptors in glomerular hyperfiltration in streptozotocin-induced diabetic rats

BACKGROUND: Since adrenomedullin (AM) elicits vasodilatation by binding to specific AM receptors consisted of calcitonin-receptor-like receptor (CRLR)/receptor-activity-modifying protein 2 (RAMP2) or CRLR/receptor-activity-modifying protein 3 (RAMP3) on endothelial cells and stimulating nitric oxide production, AM possibly involves in glomerular capillary dilatation in early phase of diabetic nephropathy. METHODS: Streptozotocin (STZ)-induced diabetic Sprague-Dawley rats at 4 weeks after the injection were employed for expression studies of AM, RAPM2, and RAMP3. The measurement of AM peptide levels in kidney tissue, plasma, and urine was performed. Human aortic endothelial cells (HAEC) were used to investigate functional link between glucose-induced AM production and nitric oxide release. RESULTS: STZ rats showed glomerular hypertrophy and increased urinary NO2- and NO3- excretion. By Northern blot analyses, AM and RAPM2 mRNAs significantly increased in the kidneys of STZ rats, while RAMP3 mRNA was not altered. In STZ rats, AM peptide was actively secreted into urine (1280 +/- 360 fmol/day vs. control 110 +/- 36 fmol/day). AM peptide was mainly detected on cortical and medullary collecting duct cells in control rat kidneys and AM peptide and mRNA were up-regulated on afferent arterioles and glomeruli of STZ rats. RAMP2 expression was detected on afferent arterioles and not in glomeruli in control rats and it was up-regulated on glomerular endothelial cells in STZ rats. In HAEC culture, d-glucose stimulated AM and nitric oxide production and they were suppressed by addition of AM antisense oligodeoxynucleotides. CONCLUSION: Up-regulated expression of AM and RAMP2 in afferent arterioles and glomeruli may be related to selective dilatation of glomerular capillary in acute phase of type 1 diabetes.     

Differential effects of insulin-like growth factor binding proteins-1, -2, -3, and -6 on cultured growth plate chondrocytes

BACKGROUND: In children with chronic renal failure (CRF), impairment of longitudinal growth is in part due to excess amounts of circulating high-affinity insulin-like growth factor binding proteins (IGFBPs) that might decrease or prevent insulin-like growth factor (IGF) binding to its signaling receptor. However, it appears from the clinical studies that various IGFBPs may have contrasting effects on longitudinal growth. Because of the potential importance of the IGFBPs as modulators of longitudinal growth in pediatric CRF, the aim of the present study was to investigate the biological effects of IGFBP-1, -2, -3, and -6 on cultured growth plate chondrocytes that express the type 1 IGF receptor. METHODS: The effects of exogenous IGFBPs on IGF-independent and IGF-dependent proliferation of rat growth plate chondrocytes in primary culture were investigated. Proliferation was assessed by colony formation of agarose-stabilized long-term suspension cultures and by the [3H]thymidine assay. The effects of IGFBPs on IGF-I binding and the binding of IGFBPs to chondrocytes were assessed by binding studies with radiolabeled proteins in monolayer culture. RESULTS: Intact IGFBP-1, IGFBP-2 and IGFBP-6 inhibited in equimolar concentration the IGF-I- and IGF-II-stimulated DNA synthesis and cell proliferation, whereas the biological activity of IGFBP-3 was complex. It had an IGF-independent antiproliferative effect and also inhibited IGF-dependent chondrocyte proliferation under coincubation conditions, whereas under preincubation conditions IGFBP-3 enhanced IGF-I-responsiveness. Studies on the mechanism by which IGFBP-3 potentiated IGF activity demonstrated that under preincubation conditions IGFBP-3 is capable to associate with the cell membrane and to facilitate IGF-I cell surface binding. CONCLUSIONS: Intact IGFBP-1, IGFBP-2 and IGFBP-6 act exclusively as growth inhibitors on IGF-dependent proliferation of growth plate chondrocytes. IGFBP-3, however, can either inhibit IGF-independent and IGF-dependent cell proliferation, or enhance IGF responsiveness of chondrocytes dependent on the temporal relationship to the IGF exposure.     

The effect of growth hormone on the development of diabetic kidney disease in rats.

BACKGROUND: Nephropathy is the most severe complication of diabetes mellitus. We investigated the effect of exogenous growth hormone (GH) administration on renal function and matrix deposition in the streptozotocin (STZ) model of type I-diabetic rat. METHODS: Adult female STZ-diabetic rats (D), non-diabetic control rats injected with saline (C) and control and diabetic rats injected with bovine GH for 3 months (CGH and DGH, respectively) were used. RESULTS: The usual renal hypertrophy seen in D animals was more pronounced in the DGH group. Creatinine clearance increased only in the D rats, but not in the other groups, including DGH. Albuminuria was observed in the D animals but was significantly elevated in the DGH group. Glomeruli from DGH animals showed more extensive matrix accumulation (manifested as an increase in mesangial/glomerular area ratio). Renal extractable insulin-like growth factor (IGF-I) mRNA was decreased in the D and DGH groups, but renal IGF-I protein was not significantly increased. Renal IGF binding protein-1 was increased in the D groups and further increased in the DGH group, at both the mRNA and protein levels. CONCLUSIONS: GH-treated diabetic rats had less hyperfiltration and more albuminuria, concomitant with more glomerular matrix deposition, when compared with regular diabetic animals. This was associated with a significant increase in renal IGFBP-1, and dissociated from IGF-I changes. Thus, in this model, GH exacerbates the course of diabetic kidney disease.