Both T- and K-kininogens increase in the serum of old rats but by different mechanisms.
In the rat, kininogens are produced from two distinctly regulated gene families, T- and K-kininogens. We have previously established that T-kininogen (T-KG, thiostatin) gene expression is increased in the liver of old rats, as compared to their younger counterparts. In this report, we have used Northern blot analysis to show that the steady state mRNA levels for either the LMW (Low Molecular Weight) or HMW (High Molecular Weight) forms of K-KG do not change significantly between 15 and 25 months of age. On the other hand, probing of Western blots containing total serum proteins showed that, as for T-KG, old animals have consistently elevated levels of HMW-KG. These results indicate that old rats contain elevated serum levels of both T- and K-KG. Nuclear run on experiments have shown that the increase in T-KG gene expression is controlled primarily at the transcriptional level. Our present results with K-KG, on the other hand, indicate that its expression is controlled post-transcriptionally.
Sierra
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Center for Gerontological Research, Medical College of Pennsylvania and Hahnemann University, Philadelphia 19129, USA.
D000293:Adolescent; D000328:Adult; D000375:Aging / Q000097:blood*; D000818:Animals; D001483:Base Sequence; D015415:Biomarkers / Q000097:blood; D015853:Cysteine Proteinase Inhibitors / Q000097:blood*; D018507:Gene Expression Regulation, Developmental / Q000502:physiology*; D006801:Humans; D007704:Kininogens / Q000097:blood*; D008297:Male; D008875:Middle Aged; D008969:Molecular Sequence Data; D012333:RNA, Messenger / Q000096:biosynthesis; D051381:Rats; D017207:Rats, Sprague-Dawley
D015415:Biomarkers; D015853:Cysteine Proteinase Inhibitors; D007704:Kininogens; D012333:RNA, Messenger