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Target Concepts:
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Query: EC:3.1.26.9 (
ribonuclease
)
6,589
document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)
Tenascin-X and
tenascin-C
glycoproteins are phylogenetically conserved components of the extracellular matrix, although their specific roles remain to be determined. cDNA probes were produced from pig tenascin-X and
tenascin-C
genes and were used to examine the tissue distribution of the transcripts in 28 tissues from Large-White pigs, 4.5-42-months old (called adults) and 17 tissues from 87-day-old fetuses. The hybridization of Northern blots with tenascin-X probes revealed, in most tissues, a complex pattern of bands including a major band of about 13 kb, assumed to correspond to the main tenascin-X transcript. Hybridization with the
tenascin-C
probe showed two transcripts of 6.8 kb and 8.2 kb. The data from the
ribonuclease
-protection technique showed that both genes displayed large variations in the transcription levels among the tissues analysed. Overall, the tenascin-X gene was significantly expressed in two thirds of the tissues, and the
tenascin-C
gene in about 50% of them. The highest tenascin-X signals were observed in tendons, ligaments and, unexpectedly, in peripheral nerves. Other tissues, including colon, dermis, skin, heart, uterus, stomach, jejunum, placentae, aorta, lung, mammary and adrenal glands also exhibited significant signal intensities. In fetuses, mainly testes and skeletal muscle showed higher transcription levels than the adult counterparts. The
tenascin-C
gene was predominantly transcribed in the ligament, tendon, adrenal gland and colon, and more weakly in the stomach, jejunum, lung and spinal cord. In fetuses, the
tenascin-C
signal in the brain was higher than the signal in the brain of adult, whereas the reverse was true for the adrenal gland and the colon. Within a given tissue, the level of tenascin-X and
tenascin-C
transcripts varied greatly, indicating independent tenascin-X and
tenascin-C
transcription regulation mechanisms; this was particularly obvious in adult and fetal nerves but also in the dermis, skin, heart, uterus, placentae and aorta, where tenascin-X RNA molecules were much more abundant than those of
tenascin-C
. In addition, similar differences were observed in the skeletal muscle and adrenal gland of fetuses. In contrast, the amount of
tenascin-C
transcripts in the fetal brain and adult spinal cord was higher than those for tenascin-X. Our results draw attention to a possible specific role of tenascin-X in the peripheral nerve physiology.
...
PMID:Distinct tissue distribution in pigs of tenascin-X and tenascin-C transcripts. 754 48
Localization of
tenascin-C
in vivo and cell culture experiments in vitro have provided evidence for stromal production of
tenascin-C
in malignant tumors of a variety of organs. Here we raised the question of whether the mesenchymal stroma in the case of endometrial adenocarcinoma is the unique source of
tenascin-C
. Therefore, the expression of
tenascin-C
mRNA by human endometrial adenocarcinoma cells and endometrial stroma cells was investigated. Several preparations of endometrial stroma cells produced
tenascin-C
mRNA. Using a serum-free defined cell culture medium, production of
tenascin-C
mRNA could be increased by adding either serum or 20 ng TGF-beta/mL to the cell culture medium. Reverse transcriptase polymerase chain reaction analysis revealed that five out of six endometrial adenocarcinoma cell lines produced
tenascin-C
mRNA. Northern blot experiments and
ribonuclease
protection assays provided evidence that the number of copies of
tenascin-C
mRNA was small. Analysis of expressed splice variants by reverse transcriptase polymerase chain reaction analysis revealed the abundance of one major splice variant that lacked all potential alternatively spliced fibronectin type-III-like repeats. Regarding larger splice variants, all fragment sizes that could theoretically originate from seven alternatively spliced fibronectin type-III-like repeats were observed. Evaluating relative signal intensities, the splice variants containing a single fibronectin type-III-like repeat and the variant possessing all but one alternatively spliced repeats were most frequent. In summary, evidence is provided that
tenascin-C
can originate from both tissue compartments of the human endometrium stroma and (tumor) epithelium. Splice variant analysis revealed a high number of splice variants and a relative high proportion of variants that have so far been regarded as minor constituents of expressed
tenascin-C
.
...
PMID:Expression of tenascin-C by human endometrial adenocarcinoma and stroma cells: heterogeneity of splice variants and induction by TGF-beta. 959 65
