Ramharack R, Spahr M A, Kreick J S, Sekerke C S
Department of Vascular and Cardiac Diseases, Parke-Davis Pharmaceutical Research, Division of Warner-Lambert Company, Ann Arbor, MI 48105, USA.
J Lipid Res. 1996 Sep;37(9):2029-40.
The apolipoprotein[a] (apo[a]) and plasminogen (PLG) genes share a high degree of sequence identity, suggesting that both genes may be coordinately expressed. To address this possibility, hepatic apo[a], PLG, and glyceraldehyde-3-phosphate dehydrogenase (G3PDH) mRNAs in 11 cynomolgus monkeys that express plasma Lp[a] over a 10-fold range (5.3-69.3 mg/dl) were measured. This analysis demonstrated a 13-fold variation in apo[a] mRNA. PLG mRNA levels ranged only 3-fold, which was similar to the deviation in G3PDH mRNA expression. Lp[a] and PLG plasma levels were also not related in the animals. To further define expression of the latter mRNAs, they were measured in liver and 13 extrahepatic tissues from 5 monkeys. Apo[a] transcript was detected for the first time in adrenal, lung, and pituitary in addition to brain and testes. PLG mRNA was detected extrahepatically only in testes while G3PDH mRNA was ubiquitously expressed. In individual animals, there was no relationship between hepatic and extrahepatic apo[a] mRNA levels suggesting tissue-dependent expression of the transcript. These results demonstrate that although the apo[a] and PLG genes are highly homologous, their mRNA expression differs markedly.
载脂蛋白[a]（apo[a]）基因和纤溶酶原（PLG）基因具有高度的序列同一性，这表明这两个基因可能是协同表达的。为了探究这种可能性，我们检测了11只食蟹猴肝脏中apo[a]、PLG和甘油醛-3-磷酸脱氢酶（G3PDH）的mRNA水平，这些食蟹猴血浆Lp[a]水平相差10倍以上（5.3 - 69.3 mg/dl）。分析显示apo[a] mRNA存在13倍的差异。PLG mRNA水平仅相差3倍，这与G3PDH mRNA表达的差异相似。在这些动物中，Lp[a]和PLG的血浆水平也没有相关性。为了进一步明确后两种mRNA的表达情况，我们在5只猴子的肝脏和13个肝外组织中进行了检测。除了脑和睾丸外，首次在肾上腺、肺和垂体中检测到apo[a]转录本。PLG mRNA仅在睾丸的肝外组织中被检测到，而G3PDH mRNA则广泛表达。在个体动物中，肝脏和肝外apo[a] mRNA水平之间没有相关性，这表明该转录本存在组织依赖性表达。这些结果表明，尽管apo[a]和PLG基因高度同源，但它们的mRNA表达却明显不同。
