ABSTRACT
We examined the structure of the rat kinin B2 receptor gene (KB2r) and encoding messenger RNA (mRNA) processing. Differently from the closely related mouse and rabbit genes that have three exons and two introns, the rat gene purportedly consists of four exons and three introns. There are two purported gene products; one of them contains an upstream approximately 180-bp open reading frame region ("exon-X") potentially expressed as a result of alternative processing. To examine the processing of rat KB2r mRNA, cDNA amplicons were generated using primer pairs directed towards 5' or 3' exon or intron flanking regions. Analyses of intron/exon primary cDNA amplicons showed that introns 1 to 3 are removed sequentially and that "exon-X" removal follows that of intron-3. No evidence was found for "exon-X" expression in polyadenylated (mature) mRNA of adult Wistar, Wistar Kyoto, spontaneously hypertensive or Sprague-Dawley rat tissues. Nor was "exon-X" detected in tissues subject to inflammatory stimulus expressing B1 kinin receptor mRNA or in 1- to 21-day-old rat embryos or fetuses. The lack of evidence for the expression of "exon-X" in mature mRNA indicates that the structure of the rat gene is similar to that of the mouse, rabbit and human genes, all consisting of three exons and two introns. The "exon-X" fragment may result from interstitial gene duplication, be a fragment of the ancestral gene, or most likely heterologous transposon insertion of an exon-like fragment into intron-2 of the KB2r gene.
Subject(s)
Aging/genetics , Evolution, Molecular , Fetus/metabolism , Gene Expression Regulation, Developmental , RNA Processing, Post-Transcriptional , Receptor, Bradykinin B2/genetics , Aging/drug effects , Animals , Base Sequence , Databases, Genetic , Embryo, Mammalian/drug effects , Embryo, Mammalian/metabolism , Exons/genetics , Female , Fetus/drug effects , Gene Expression Profiling , Gene Expression Regulation, Developmental/drug effects , Genome/genetics , Introns/genetics , Male , Molecular Sequence Data , Pyrogens/pharmacology , RNA Processing, Post-Transcriptional/drug effects , RNA, Messenger/genetics , RNA, Messenger/metabolism , Rats , Receptor, Bradykinin B1/genetics , Receptor, Bradykinin B1/metabolism , Receptor, Bradykinin B2/metabolismABSTRACT
Papillomavirus infection in bovines is associated with cutaneous papillomatosis on the hide, udders and other epithelial tissues, as well as in oral respiratory, alimentary and urinary tract mucosa. Bovine papillomavirus (BPV) is also considered the etiological agent of esophageal tumors and the malignant bladder tumors that characterize the clinical condition associated with chronic enzootic hematuria. After infective viral DNA was found in cattle blood and BPV1, 2 and 4 DNA in cattle reproductive and embryonic tissues, we looked for and found BPV DNA in blood, milk, urine, seminal fluid, and spermatozoa of BPV-infected animals. Peripheral blood lymphocyte cultures from BPV-infected animals had high rates of chromosome aberrations, including radial rearrangements that signal oncogenic potential and viral interaction with telomeric regions. The finding of BPV DNA in body fluids and tissues other than the epithelium demonstrates co-infection of other tissues or cell types by papillomavirus and shows the potential role of lymphocytes, seminal fluid and spermatozoa in BPV transmission. Our findings reinforce a peremptory need for prophylactic and therapeutic instruments to curtail this disease in bovine livestock.
