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T R Hansen

Publications and source records attributed to T R Hansen.

At least 37 records · Page 2Linked to original sources
PubMed1999

Pregnancy-specific protein B induces release of an alpha chemokine in bovine endometrium.

Pregnancy-specific protein B (PSPB), is secreted from binucleate trophoblast of the bovine conceptus as early as day 15 of pregnancy. The objective of this experiment was to determine if PSPB induced uterine proteins. PSPB was purified from day 120 cotyledons using antibody-based affinity chromatography. Endometrium from day 14 nonpregnant cows (n = 3) was prepared for explant (3H-Leu added) culture. Radiolabeled proteins released into medium were dialyzed, separated using 1D-PAGE, and detected using fluorography and densitometry. PSPB (0, 0.5, 5, 25 & 50 nM) caused a concentration-dependent increase in the release of a radiolabeled 8-kDa uterine protein. Western blots revealed that the 8-kDa protein cross-reacted with antibody against granulocyte chemotactic protein-2 (GCP-2). PSPB also induced release of GCP-2 by bovine endometrial (BEND) cells in primary culture. The induction of GCP-2 by PSPB was blocked by addition of antiserum against PSPB (1:4 molar ratio). This is the first indication that PSPB has a hormonal role in inducing GCP-2, an alpha chemokine that also is induced by interferon-tau during early pregnancy. This chemotactic cytokine may be integral to mediating adhesion, inflammation and angiogenesis associated with early implantation.

Animals↗
PubMed1999

Cloning of interferon-stimulated gene 17: the promoter and nuclear proteins that regulate transcription.

A member of the interferon-stimulated gene (ISG) family encodes a 17-kDa ubiquitin homolog called ISG17 that is induced in the bovine uterine endometrium by interferon-tau (IFN-tau) during early pregnancy. The bovine (b) ISG17 cDNA shares 30% identity with a tandem ubiquitin repeat and 70% identity with human (h) ISG15. The present experiments were designed to sequence the bISG17 gene, compare general structure with the hISG15 gene, and to identify transcription factors that were induced by IFN-tau in bovine endometrial (BEND) cells. The promoter of the bISG17 gene was similar to the hISG15 gene in placement of a tandem IFN-stimulatory response element (ISRE) at position -90, but unique in the presence of three additional ISREs at positions -123, -332, and -525. IFN-tau (25 nM) induced nuclear proteins in BEND cells that interacted with a tandem bISG17 ISRE in electrophoretic mobility shift assay (EMSA). IFN-regulatory factor-1 (IRF-1) bound to this ISRE based upon supershift EMSA using antiserum against IRF-1. IFN-tau activated STAT-1 (signal transducer and activator of transcription-1) and -2 by 0.5 h, and IRF-1 by 2 h in BEND cells. It is concluded that the bISG17 gene is similar to the hISG15 gene, retains an ISRE that interacts with IRF-1, and is possibly induced initially by the STATs and later by IRF-1 in response to IFN-tau during early pregnancy.

Amino Acid Sequence↗
PubMed1999

Mechanism of action of interferon-tau in the uterus during early pregnancy.

Early pregnancy is maintained in ruminants through the actions of conceptus-derived interferon (IFN)-tau on the endometrium. IFN-tau alters uterine release of PGF2 alpha' which results in rescue of the corpus luteum and continued release of progesterone. The mechanism of action of IFN-tau includes inhibition of oestradiol receptors, consequent reduction in oxytocin receptors, activation of a cyclooxygenase inhibitor, and a shift in the PGs to favour PGE2 over PGF2 alpha' IFN-tau also induces several endometrial proteins that may be critical for survival of the developing embryo. One endometrial protein induced by pregnancy and IFN-tau has been identified as bovine granulocyte chemotactic protein-2 (bGCP-2). This chemotactic cytokine (chemokine) has been used as a marker to delineate IFN-tau from IFN-alpha responses in the endometrium. A second protein, called ubiquitin cross-reactive protein (UCRP), resembles a tandem ubiquitin repeat. UCRP becomes conjugated to cytosolic endometrial proteins in response to IFN-tau and pregnancy. Proteins conjugated to UCRP are either modulated or targeted for processing through the proteasome. The action of IFN-tau is mediated by induction of signal transducer and activator of transcription 1 (STAT-1), STAT-2 and interferon regulatory factor 1 (IRF-1) transcription factors. Induction of these transcription factors, the alpha chemokines and UCRP is the prelude to maternal recognition of pregnancy in ruminants.

Amino Acid Sequence↗
PubMed1998

Inhibition by tocopherol of prostaglandin-induced apoptosis in ovine corpora lutea.

Accumulation of toxic oxidants within corpora lutea is a prelude of apoptotic cell death. Vitamin E (alpha-tocopherol) is a biological antioxidant that protects cells from the inductive effects of reactive oxygen on DNA damage and nuclear/cytoplasmic condensation that dictate apoptosis. Ewes were challenged with a luteolytic dose of PGF2 alpha on d 10 of the estrous cycle. The acute decline in circulatory progesterone indicative of the onset of functional luteolysis was not affected by systemic administration of alpha-tocopherol; however, corpora lutea consequently (beyond 24 h) rebounded from the steroidogenic insult. Luteal tissues obtained at 24 h after PGF2 alpha revealed that internucleosomal DNA fragmentation and cellular collapse were inhibited by alpha-tocopherol. These observations indicate that regressive corpora lutea can be spared from terminal involution by diminishing the apoptotic influence of luteolytic hormone with an antioxidant.

Animals↗
PubMed1998

Pregnancy and interferon-tau induce conjugation of bovine ubiquitin cross-reactive protein to cytosolic uterine proteins.

Conceptus-derived interferon-tau (IFN-tau) induces bovine endometrial ubiquitin cross-reactive protein (UCRP) mRNA and protein on Days 15-21 of pregnancy. Bovine UCRP retains the Leu-Arg-Gly-Gly C-terminal sequence of ubiquitin that ligates to and directs degradation of cytosolic proteins. The objectives of the present experiments were to determine whether UCRP became conjugated to endometrial cytosolic proteins during early pregnancy and in response to recombinant bovine (rbo) IFN-tau. Ubiquitin (8 kDa), UCRP (17 kDa), and conjugates thereof (> or = 30 kDa) were quantitated using Western blotting and densitometry. Endometrial ubiquitin and its conjugates did not differ between Day 18 pregnant and nonpregnant cows, or between control and rboIFN-tau-treated (25 nM) explant cultures (Day 14; nonpregnant). Bovine UCRP was induced in endometrium from pregnant as compared with nonpregnant cows. Conjugation of endometrial proteins to UCRP was induced in pregnant as compared to nonpregnant cows. Recombinant boIFN-tau induced UCRP and its conjugates in cultured endometrial explants from nonpregnant cows. It is concluded that UCRP, in response to rboIFN-tau, becomes conjugated to endometrial cytosolic proteins during early pregnancy. The regulation of uterine proteins by UCRP may be integral to the maintenance of early pregnancy in ruminants.

Amino Acid Sequence↗
PubMed1998

Complex induction of bovine uterine proteins by interferon-tau.

Interferon-tau (IFN-tau) is released by the conceptus and induces two uterine proteins during early pregnancy: ubiquitin cross-reactive protein (UCRP) and granulocyte chemotactic protein-2 (GCP-2). The present experiments were designed to determine whether detection (Western blot) of cytosolic UCRP and release of GCP-2 could be used to examine IFN-tau signal transduction in cultured endometrial explants and primary epithelial cells. Recombinant (r) type 1 IFNs (rboIFN-tau and rboIFN-alpha; 5, 25, 100 nM) induced UCRP, but only rboIFN-tau induced GCP-2 in explant culture. Recombinant boIFN-tau and conceptus secretory proteins containing native IFN-tau induced UCRP and GCP-2 in cultured primary epithelial cells. All concentrations of rboIFN-alpha (25, 50, 100 nM) induced UCRP, but only the highest concentration induced GCP-2 in cultured primary epithelial cells. Interestingly, phorbol ester (100, 500, 1000 ng/ml) induced GCP-2, but it had no effect on UCRP. Because type 1 IFNs induce UCRP, IFN-tau probably interacts with the janus kinase (Jak)-associated IFN-alpha receptor to phosphorylate signal transducers and activators of transcription (STAT) and/or interferon regulatory factor-1 (IRF-1). However, IFN-tau-specific induction of GCP-2 may involve a variant type 1 receptor subunit or activators of transcription that are associated with protein kinase C and the Jak/STAT/IRF-1 pathway.

Animals↗
PubMed1997

Increased bax and interleukin-1beta-converting enzyme messenger ribonucleic acid levels coincide with apoptosis in the bovine corpus luteum during structural regression.

Recent reports have demonstrated that prostaglandin F2alpha-induced generation of reactive oxygen species or their intermediates inhibits progesterone synthesis and may also serve as a trigger for apoptosis in the corpus luteum (CL). BCL-2, an inhibitor of apoptosis in a wide variety of cell types, has been reported to prevent oxidative stress-induced cell death. Thus, the present studies were conducted to determine whether levels of mRNA encoding BCL-2 and related members of this gene family (BAX and BCL-Xshort, which induce apoptosis; BCL-Xlong, a BCL-2 homologue that prevents apoptosis) differed in functional (Day 21 of pregnancy) versus regressed (Day 21 of the estrous cycle) CL in the bovine ovary. Levels of mRNAs encoding p53, a transcriptional regulator of the bcl-2 and bax genes, and interleukin-1beta-converting enzyme (ICE), a protein recently implicated in the induction of apoptosis whose expression may be enhanced by oxidative stress, were also assessed. Partial cDNA clones encoding bovine bax, bcl-x, p53, and Ice were isolated using the reverse transcriptase-polymerase chain reaction (RT-PCR) technique with total RNA prepared from functional or regressed CL. A bovine bcl-2 cDNA could not be isolated from luteal tissue RNA despite the use of several primer pairs for amplification. Total RNA was then extracted from functional or regressed CL and analyzed by Northern blot analysis. The occurrence of apoptosis in regressed CL, as evidenced by the presence of internucleosomal DNA cleavage, was associated with a significant increase in both bax and Ice mRNA levels as compared with levels of bax and Ice expression in functional CL (p < 0.05, n = 3). There were no significant differences in bcl-x or p53 mRNA levels in functional versus regressed CL. Analysis of bcl-x mRNA by RT-PCR revealed that the long form was the primary, if not only, mRNA expressed in functional and regressed bovine luteal tissue. On the basis of data that increased expression of bax is associated with, and may be required for, apoptosis in ovarian granulosa cells and germ cells, we propose that BAX may play a similar role in apoptosis induction during luteal regression. Moreover, the increased Ice mRNA levels in regressed CL provides the first evidence that the ICE family of death proteases may be involved in luteolysis.

Animals↗
PubMed1997

Transient ubiquitin cross-reactive protein gene expression in the bovine endometrium.

Bovine ubiquitin cross-reactive protein (boUCRP) is secreted by the endometrium from days 15 to 26 of pregnancy in response to conceptus-derived interferon-tau (IFN-tau). We hypothesized that the gene encoding boUCRP was under transcriptional control by the conceptus and IFN-tau. Northern blots using radiolabeled UCRP cDNA revealed a single UCRP transcript of approximately 700 b that was present (P < 0.05) in endometrial cells cultured with 25 nM rboIFN-tau. The UCRP mRNA was not detected in endometrium on days 15, 17, 18 or 19 of the estrous cycle (n = 4 cows on each day) or in spleen, kidney, liver, corpus luteum or muscle. Bovine UCRP mRNA was detectable (P < 0.05) in endometrium from pregnant cows by day 15, reached highest levels by day 17, remained elevated on days 18, 19 and 21, and then declined to amounts on day 26 that were not detectable. Northern blot using radiolabeled ubiquitin cDNA revealed presence of the two major ubiquitin transcripts UbB (1.2 Kb) and UbC (2.6 Kb) in all tissues examined. The bovine UCRP cDNA did not cross-hybridize with these ubiquitin transcripts. We conclude that transcription of the UCRP gene is transient during early pregnancy and regulated by IFN-tau.

Animals↗
PubMed1997

Bovine granulocyte chemotactic protein-2 is secreted by the endometrium in response to interferon-tau (IFN-tau).

Interferon-tau (IFN-tau) is secreted by the bovine conceptus and may regulate synthesis of uterine endometrial cytokines to provide an environment that is conductive to embryo development and implantation. Interferon-tau stimulates secretion of an 8-kDa uterine protein (P8) in the cow. P8 was purified, digested to yield internal peptides, and partially sequenced to determine identity. Two internal peptides had 100% (13-mer) and 92% (12-mer) amino acid sequence identity with bovine granulocyte chemotactic protein-2 (bGCP-2). Bovine GCP-2 is an alpha-chemokine that acts primarily as a potent chemoattractant for granulocyte cells of the immune system. A peptide was synthesized based on a region of bGCP-2 that overlapped with a P8 peptide amino acid sequence, coupled to keyhole limpet hemocyanin, and used to generate high titer polyclonal antiserum in sheep. Western blots revealed that bGCP-2 was not released by endometrium from day 14 nonpregnant cows, but was released in response to 25 nM IFN-tau (p<0.05). Uterine GCP-2 exhibited high affinity to heparin agarose, a characteristic shared by all alpha chemokines. This is the first report describing presence of GCP-2 in the uterine endometrium and regulation by IFN-tau. The regulation of bGCP-2 by IFN-tau may have important implications for cytokine networking in the uterus during pregnancy. Also, the regulation of inflammation and angiogenesis by bGCP-2 working together with other cytokines may be integral to establishing early pregnancy and implantation in the cow.

Amino Acid Sequence↗
PubMed1996

Pepsin-inhibitory activity of the uterine serpins.

Among the major products secreted by the uteri of cattle, sheep, and pigs during pregnancy are glycoproteins with amino acid sequences that place them in the serpin (serine proteinase inhibitor) superfamily of proteins. The inferred amino acid sequences for bovine uterine serpin (boUS-1) and ovine uterine serpin (ovUS-1) exhibit about 72% sequence identity to each other but only about 50% and 56% identity, respectively, to two distinct porcine uterine serpins (poUS-1 and poUS-2). Despite these differences in primary structure, the uterine serpins possess well-conserved reactive center loop regions that contain several motifs present in the propeptide regions of pepsinogens. One such motif, VVVK, aligns with the first 4 amino acids of the aspartic proteinase inhibitor pepstatin. Although no inhibitory activity toward any serine proteinase has been found, at least one of the uterine serpins, ovUS-1, can bind specifically to immobilized pepsin A and can weakly inhibit the proteolytic activities of pepsin A and C (but not cathepsins D and E). OvUS-1 is the first specific inhibitor of aspartic proteinases to be identified in vertebrates and provides another example of a serpin with "crossover" activity. The pregnancy-associated glycoproteins (PAGs), which are secreted by the trophoblast layer of the placentas of ungulate species and are inactive members of the aspartic proteinase family, can also bind ovUS-1 and may be the natural target partners for the uterine serpins.

Amino Acid Sequence↗
PubMed1996

Ubiquitin cross-reactive protein is released by the bovine uterus in response to interferon during early pregnancy.

A 16-kDa protein has been identified that is secreted by the bovine endometrium in response to conceptus-derived interferon (IFN)-tau during early pregnancy. Because this uterine protein was similar in size to a human ubiquitin cross-reactive protein (hUCRP) that also was regulated by IFN, we suspected that they might be related. To test this hypothesis, uterine flushings, medium from cultured endometrium, and endometrial tissues were examined for the presence of ubiquitin-immunoreactive proteins. Immunoreacting proteins were detected through use of one-dimensional (1D)-PAGE and Western blotting with ubiquitin and hUCRP antiserum (1:500). A 16-kDa protein that cross-reacted with ubiquitin and hUCRP antisera was released by the endometrium and was present in uterine flushings from all Day 18 pregnant females examined (n = 12). The immunoreacting 16-kDa protein was absent in all nonpregnant females examined (n = 23). Regulation of this uterine protein by recombinant type I IFNs (rbIFN-tau, rbIFN-alpha, and roIFN-tau), using 0, 0.5, 5, and 25 nm of each IFN, was evaluated in nonpregnant (Day 12) heifers (n = 5) using 1D-PAGE and Western blotting. Release of the 16-kDa protein into medium was negligible in controls (0 nm IFN). For each IFN, a dose-dependent increase (p < 0.05) in release of the immunoreacting 16-kDa protein was noted. We conclude that the 16-kDa protein that is produced by the endometrium in response to IFN-tau during early pregnancy also shares epitopes with hUCRP and ubiquitin. The 16-kDa protein has been named bovine UCRP.

Animals↗
PubMed1996

Polyubiquitin up-regulation in corpora lutea of prostaglandin-treated ewes.

Genes that encode mRNAs for ubiquitin are activated by cells in metabolic distress. Cytosolic proteins that consequently become conjugated to ubiquitin are targeted for degradation. We hypothesized that ubiquitin mediates the endocrine demise of the corpus luteum induced by prostaglandin (PG) F2 alpha. Indeed, polyubiquitin gene expression increased abruptly (within 2 h) in luteal tissues of ewes treated with PGF2 alpha-before the precipitous decline in glandular progesterone accumulation indicative of functional luteolysis. A corresponding elevation in ubiquitin immunostaining was localized to large (PG-sensitive) luteal cells. It is suggested that luteal progesterone biosynthesis is disrupted by ubiquitination of steroidogenic regulatory proteins-perhaps those involved in the mechanics of mitochondrial delivery and side-chain cleavage of cholesterol.

Animals↗
PubMed1996

Polyubiquitin up-regulation in corpora lutea of prostaglandin-treated ewes.

Genes that encode mRNAs for ubiquitin are activated by cells in metabolic distress. Cytosolic proteins that consequently become conjugated to ubiquitin are targeted for degradation. We hypothesized that ubiquitin mediates the endocrine demise of the corpus luteum induced by prostaglandin (PG) F2alpha. Indeed, polyubiquitin gene expression increased abruptly (within 2 h) in luteal tissues of ewes treated with PGF2alpha--before the precipitous decline in glandular progesterone accumulation indicative of functional luteolysis. A corresponding elevation in ubiquitin immunostaining was localized to large (PG-sensitive) luteal cells. It is suggested that luteal progesterone biosynthesis is disrupted by ubiquitination of steroidogenic regulatory proteins--perhaps those involved in the mechanics of mitochondrial delivery and side-chain cleavage of cholesterol.

Animals↗
PubMed1995

Baculovirus-insect cell production of bioactive choriogonadotropin-immunoglobulin G heavy-chain fusion proteins in sheep.

A hybrid cDNA encoding a fusion protein between the beta subunit of hCG (beta hCG) and constant domains of a mouse IgG heavy chain (CH1-3) was inserted into a baculovirus expression vector. Insect cells transfected with foreign DNA synthesized multimeric forms of fusion protein that inhibited hCG-induced steroid hormone secretion by mouse Leydig tumor cells. Leydig cells were lysed by beta hCG-CH1-3 in the presence of complement. Intravenous injection of beta hCG-CH1-3 in rams was associated with testicular mononuclear leukocyte infiltration, interstitial tissue damage, and a transient depression in circulatory testosterone (levels returned to normal within 2 wk). It appears that targeted cell-killing can be mediated by recombinant proteins composed of the receptor-binding moiety of hormones and truncated effector (Fc) regions of lethal antibodies.

Animals↗
PubMed1995

Secretion of bovine uterine proteins in response to type I interferons.

Bovine interferon-tau (bIFN-tau) is secreted by the developing conceptus and initiates antiluteolytic events by interacting with uterine membrane receptors. We have identified three endometrial proteins (approximately 8, 16, and 28 kDa; P8, P16, and P28; respectively) that are secreted in response to recombinant (r) bIFN-tau. The objective of this study was to determine whether or not secretion of these proteins was a unique response to IFN-tau during early pregnancy. Three experiments were designed to examine secretion of endometrial proteins as a function of time in culture (0, 3, 6, 12, 18, 24 h), stage of the estrous cycle and pregnancy (Days 15, 18, 0/21), and dose of Type I IFN (0, 0.5, 5, and 25 nM; rbIFN-tau, rbIFN-alpha, and roIFN-tau). Endometrium was cultured for times specified with L-[3H]leusine to generate radiolabeled proteins. Secreted proteins were quantitated by using one-dimensional (1D)-PAGE, fluorography, and densitometry. Secretion of P8, P16, and P28 increased over time (p < 0.0001) in culture and in response to 25 nM rbIFN-tau (p < 0.05). Secretion of P8 in response to rbIFN-tau was higher (p < 0.05). Secretion of P8 in response to rbIFN-tau was higher (p < 0.0005) in endometrium collected from pregnant than nonpregnant heifers, but did not differ across the days examined. Although secretion of P8 was higher (p < 0.0001) in the presence than in the absence of rbIFN-tau, it was not affected by rbIFN-alpha.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1993

Recombinant interferon-tau regulates secretion of two bovine endometrial proteins.

Conceptus-derived interferon-tau (IFN-tau) has been implicated in the process of maternal recognition of pregnancy in the bovine. This type I IFN interacts with a uterine receptor complex to elicit secondary maternal responses, one of which is secretion of uterine proteins. We investigated the effects of pregnancy and recombinant (r) bovine (bo) IFN-tau (10(7) antiviral units/mg) on secreted proteins by cultured bovine endometrial explants. Explants were cultured for 24 h with [3H]leucine and dialyzed medium analyzed by one- and two-dimensional SDS polyacrylamide gel electrophoresis (PAGE) and fluorography. In one-dimensional PAGE experiments, endometrium representing early pregnancy (days 16-21) and the estrous cycle (days 16-19) was cultured in the presence of 5 nM rboIFN-tau and showed an increase (two- to five-fold) in secretion of 12- and 28-kD proteins. Further examination of these proteins by using two-dimensional PAGE indicated that the 12-kD protein was basic (pI > or = 7.5), whereas the 28-kD protein was acidic (pI approximately 5.0). Isoelectric focusing in the acidic range revealed that the 28-kD protein was composed of several isoelectric variants (pI 4.5-5.5). Although the functions of these secretory proteins are currently unknown, they serve as useful markers for IFN action and may act as secondary signals to protect the early developing conceptus.

Animals↗
PubMed1992

Nucleotide and amino acid sequence of pap-gene (pediocin AcH production) in Pediococcus acidilactici H.

N-terminal analysis of purified pediocin AcH produced a partial sequence of 23 amino acids. This sequence matched perfectly with a segment of 23 amino acids in a 62 amino acid molecule generated from the 186 nucleotide sequence open reading frame in a Hind III fragment in pSMB74 encoding pap-gene (pediocin AcH production). It is suggested that the molecule is translated as inactive prepediocin AcH of 62 amino acids. Then through enzymatic modifications the leader segment of 18 amino acids is removed from the NH2-terminal. The remaining segment of 44 amino acids is active pediocin AcH of 4628 M(r).

Amino Acid Sequence↗