[Comparison studies on pharmacodynamics of three kind of Carapax trionycis]

Three kinds of Carapax Trionycis were used in rat to prevent and treat syndrom-complex of dificiency of Yin. Compareing the improvement of symptoms of dificiency of Yin, it was found that all of them actted effectively in various degrees. The effect of ZhongHua Carapax Trionycis (ZHCT) was similar to those of Shan Rui Carapax Trionycis (SRCT), but the efficacy of Green Carapax Trionycis (GCT) was inferior to those of ZHCT and SRCT. All kinds of C. Trionycis could increase the function of responding to iriation in mice with deficiency of Yin. The intensity of ZHCT was similar to that of GCT, and superior to that of SRCT. They all could enhance phagocytic function of eticuloedothelial system obviously, promot the development of thymus in different degrees with no efect on spleen in young mice. The efficacy of increasing the immune function of ZHCT and GCT were more potent than that of SRCT. ZHCT and GCT significantly decreased the activity of SGPT in mice poisoned by CC14. ZHCT and GCT protected liver better than SRCT did.

[Antisense N-ras1 gene inhibits the proliferation of VSMC induced by bFGF after arterial injury]

OBJECTIVE

To develop a new way to prevent the process of restenosis after arterial injury, we transfer the recombinant antisense N-ras1 gene to the cultured SMCs and studied the influence of gene therapy with antisense N-ras1 on the SMCs proliferation induced by bFGF.

METHODS

With the recombinant antisense N-ras1 plasmids (fpGv1-MT-N-ras1) transfered to the cultured SMC, we studied the effect on the SMCs proliferation induced by bFGF.

RESULTS

The results of the experiment indicated that the count of cells transfered antisense N-ras1 was 16.8 +/- 1.3 x 10(4), the control cells transfered fpGv1-MT retrovirus vector were 30.1 +/- 1.2 x 10(4) (cell/ml) (P < 0.001). cell [3H] thymedine incorporation was 7,643 +/- 672 cpm in gene therapy cells, and 15,131 +/- 138 cpm in vector control cells (P < 0.001). Gene therapy cells ras mRNA and p21 were significantly decreased by Northern blotting and Western blotting technique.

CONCLUSION

These results suggest that antisense N-ras1 gene may inhibit the proliferation of cultured VSMC induced by bFGF.

Staged sequential reconstruction of a total lower lip, chin, and anterior mandibular defect

The combination of a total lower lip, chin, and anterior mandibular defect following cancer resection is an extremely complex problem that requires a sequence of operations to optimize functional and aesthetic results. One patient is presented in whom the defect was reconstructed with a free fibular flap followed by a series of ancillary procedures using both modern and traditional techniques. At the time of tumor ablation, the through-and-through oromandibular defect was reconstructed with a fibular osteocutaneous flap. The lower lip and gingivolabial sulcus was reconstructed later with a tongue flap. Tissue expansion was subsequently used to replace the fibular skin with expanded submental hair-bearing skin. A polyethylene implant was added later to the fibular bone for chin augmentation. Subsequently the lower lip was supported with a tendinous graft suspended to the anterior masseter bilaterally. Lastly, the vermilion border was elevated by removing a rim of the tongue flap and covering the secondary wound with a full-thickness skin graft. At the end of the reconstructive procedures, lip seal and oral aperture were good with no drooling and excellent speech.

Interferon action and apoptosis are defective in mice devoid of 2',5'-oligoadenylate-dependent RNase L

2',5'-Oligoadenylate-dependent RNase L functions in the interferon-inducible, RNA decay pathway known as the 2-5A system. To determine the physiological roles of the 2-5A system, mice were generated with a targeted disruption of the RNase L gene. The antiviral effect of interferon alpha was impaired in RNase L-/- mice providing the first evidence that the 2-5A system functions as an antiviral pathway in animals. In addition, remarkably enlarged thymuses in the RNase L-/- mice resulted from a suppression of apoptosis. There was a 2-fold decrease in apoptosis in vivo in the thymuses and spleens of RNase L-/- mice. Furthermore, apoptosis was substantially suppressed in RNase L-/- thymocytes and fibroblasts treated with different apoptotic agents. These results suggest that both interferon action and apoptosis can be controlled at the level of RNA stability by RNase L. Another implication is that the 2-5A system is likely to contribute to the antiviral activity of interferon by inducing apoptosis of infected cells.

Preservation of functioning human thyroid "organoids" in the scid mouse. IV. In vivo selection of an intrathyroidal T cell receptor repertoire

To study the in vivo influence of thyroid cells on the T cell receptor repertoire in human autoimmune thyroid disease, we mixed lymphocyte-free thyrocytes (approximately 1.2 x 10[6]) from patients with Graves' disease with autologous peripheral blood mononuclear cells (PBMC; approximately 1.5 x 10[6]) and transplanted this mixture sc into scid mice while suspended in a basement membrane gel (approximately 0.4 ml). Controls included mice that received either thyrocytes only or PBMC only. The resulting artificial mixed cell thyroid organoids were explanted after 5 weeks, and their T cell receptor repertoire was examined. Of a total of 63 organoids constructed, 60 were recovered (95.2%). Total RNA was extracted and then analyzed by reverse transcription-PCR primarily for human T cell receptor (hTcR) Vbeta gene expression using 21 hTcR Vbeta amplimers. A restricted pattern of hTcR Vbeta gene expression was found, with 6 Vbeta genes (Vbeta5, 6, 7, 8, 13.1, and 18) predominantly expressed [P < 0.05, by ANOVA on ranks and Student-Newman-Keul's (SNK) test]. PBMC and control organoids showed no preferential selection of particular hTcR V gene-expressing T cells. This reductionist, mixed cell, thyroid model reflected earlier observations in human and murine autoimmune thyroid diseases in which a bias in hTcR V gene family expression had been observed. The model permitted in vivo T cell selection and/or enrichment of potentially disease relevant human T cells.

[Phase III clinical studies with ondansetron (Qilu) in the prophylaxis of nausea and vomiting induced by non-cisplatin chemotherapy]

OBJECTIVE

This study was undertaken to further determine the clinical value of ondansetron (OND, supplied by Qilu Pharmaceutical Company) in the prophylaxis of nausea and vomiting induced by non-cisplatin chemotherapy.

METHODS

A total of 193 patients were enrolled in the multicenter prospective study and were given treatment of non-cisplatin based chemotherapy. All patients were treated with OND 8 mg i.v. once a day during chemotherapy, followed by OND 4 mg orally twice a day for one day after chemotherapy.

RESULTS

The effective control rate (0-2 emetic episodes) on the first day was 93.3%. Total control of delayed vomiting (day 2-5) was as high as 94.8 to 99.5%. The mean frequency of vomiting was 0.4, 0.4, 0.2, 0.1 and 0.1, respectively from day 1 to day 5. Adverse effects were minor and tolerable.

CONCLUSION

This modified regimen of treatment with OND is effective in the control of vomiting induced by non-DDP chemotherapy.

Direct interactions of human natural killer cells with Cryptococcus neoformans inhibit granulocyte-macrophage colony-stimulating factor and tumor necrosis factor alpha production

Human natural killer (NK) cells and T lymphocytes can bind to and inhibit the growth of the yeast-like organism Cryptococcus neoformans. Binding of target cells to NK or T cells also has the potential to modulate cytokine production by the effector cells. In this study, we assessed the ability of C. neoformans to modulate NK cell production, or in some cases T-cell production, of granulocyte-macrophage colony-stimulating factor (GM-CSF) or tumor necrosis factor alpha (TNF-alpha). We found that freshly isolated human NK cells from most individuals make GM-CSF and TNF-alpha constitutively when cultured in vitro. The addition of C. neoformans to T-cell fractions which do not make GM-CSF constitutively did not affect GM-CSF production, but the addition of C. neoformans to NK cell fractions significantly reduced the amounts of GM-CSF produced in most NK cell samples. The reduction in the amount of GM-CSF in C. neoformans-NK cell cocultures could not be attributed to loss of lymphocyte viability or to C. neoformans adsorbing or degrading the cytokine and was dependent on direct contact between the NK cells and cryptococcal cells. GM-CSF was not the only cytokine to be down-regulated. TNF-alpha production was also diminished when NK cells were incubated with C. neoformans. The regulation of both cytokines was at the transcriptional level because GM-CSF and TNF-alpha mRNA levels were lower in NK cell samples incubated with C. neoformans than in NK cell samples incubated without C. neoformans. Diminished production of constitutively produced cytokines resulting from the interaction of NK cells with cryptococcal cells has the potential to affect phagocytic cells in the immediate regional environment and to damp the immune response.

Detection of major T cell epitopes on human thyroid stimulating hormone receptor by overriding immune heterogeneity in patients with Graves' disease

To examine the major immunogenic regions of the human TSH receptor (hTSHR), we examined 14 patients with Graves' disease and 14 healthy control subjects for their peripheral blood T cell proliferative responses to 29 synthetic peptides representing the entire ectodomain of the hTSHR (TSHR-ecd). By combining an analytical approach encompassing the grading of peptide-induced responses and nonparametric testing, we obtained evidence for highly significant differences (P = < 0.000001) in the patient group compared with minor differences in the control group (P = 0.045). To account for this difference, we identified four major T cell epitopes (amino acid 247-266, 202-221, 142-161, and 52-71), by multiple comparison analysis, in the patient group. Furthermore, we demonstrated by radiolabeled PCR that the responding T cells were clonally expanding. These findings demonstrate that despite likely differences in human leukocyte antigen type among patients with Graves' disease, several distinct hTSHR epitopes elicited significant responses in the immune system of patients with Graves' disease, and that such patients are most often poorly tolerant to particular epitopes of the TSH receptor ectodomain, The data support the notion of TSHR peptide antigens overriding human immune heterogeneity in patients with Graves' disease, and raise the possibility of applying analog peptide blockade to suppress T cell responsivity.

[Phase III clinical studies with ondansetron (Qilu) in the prophylaxis of nausea and vomiting induced by cisplatin]

OBJECTIVE

To further evaluate the clinical usefulness of ondensetron(OND, supplied by Qilu Pharmaceutical Company) with modified regime in the prevention of cisplatin (DDP)-induced nausea and vomiting.

METHODS

A total of 773 patients were enrolled in a multicenter cooperative study. Of them, 330 patients were given i.v. OND 8 mg once or twice a day and 443 patients were given i.v. OND 8 mg plus dexamethasone(DXM) 10 mg once a day during the therapeutic period of DDP, followed by OND 4 mg orally twice a day for two days after DDP treatment.

RESULTS

Effective control of acute nausea was achieved in 86.7% and 94.8% of the patients receiving OND alone and OND plus DXM, respectively(P < 0.001). The mean frequency of vomiting was 0.9 times in OND and 0.4 times in OND plus DXM(P < 0.01). Total control of delayed vomiting (day 2-5) was comparable in both groups. Complete inhibition of vomiting (CR rate) was more frequently observed in males than in females. Adverse effects were identical and well tolerated.

CONCLUSION

OND with modified regimen is effective in the control of DDP-induced vomiting. It is more effective when OND and DXM are given than OND given alone.

Effect of urine-derived compounds on cAMP accumulation in mouse vomeronasal cells

Urine-derived compounds from the male mouse altered the levels of the second messenger molecule cAMP differentially in female mouse vomeronasal (VN) cells when compared with olfactory cilia. cAMP levels in VN cells increased after exposure to forskolin and GTP-gamma-S, while the levels decreased after exposure to the urine-derived compounds, dehydro-exo-brevicomin (DHB) and 2-(sec-butyl)-4, 5-dihydrothiazole (SBT), in a dose-dependent manner. The general odorant citronellal did not alter cAMP levels. In contrast DHB, SBT and citronellal increased cAMP levels in olfactory cilia. We concluded that urine-derived compounds exert a differential effect on cAMP accumulation in mammalian VN and olfactory receptor neurons.

Research on the mechanism of endothelin inflammatory effects on human mesangial cells

OBJECTIVE

To investigate the mechanism of endothelin (ET) inflammatory effects on human mesangial cells (HMC).

METHODS

The following experiments were performed on cultured HMC after ET-1 stimulation: (1) the expression of tumor necrosis factor-alpha (TNF alpha), interleukin-1 beta (IL-1 beta), intercellular adhesion molecule-1 (ICAM-1), vascular cell adhesion molecule-1 (VCAM-1) and endothelin-1 (ET-1) itself messenger ribonucleic acid (mRNA) was determined by Northern Blot analysis; (2) the TNF alpha concentration was tested with radioimmunoassay; the IL-1 activity was assayed by the enhancement of thymocyte proliferation in response to mitogen; the surface expression of ICAM-1 and VCAM-1 was measured with cell enzyme linked immunoadsorbent assay (ELISA) analysis.

RESULTS

ET-1 (10(-7) mol/L) induced the following changes on HMC: (1) up-regulation of the expression of TNF alpha mRNA and protein; (2) up-regulation of the expression of ICAM-1 and VCAM-1 mRNA and protein; (3) up-regulation of the expression of ET-1 itself mRNA. However, the expression of IL-1 mRNA and protein was not changed.

CONCLUSIONS

ET-1 can stimulate HMC to produce TNF alpha, ICAM-1 and VCAM-1, and thereby induce inflammatory effects. ET-1 can also stimulate HMC to up-regulate the expression of ET-1 itself, so as to amplify inflammatory effects. So, ET-1 is actually an inflammatory mediator and may play an important role in the pathogenesis of glomerulonephritis.

[The clinical course and treatment results of lung metastases from breast cancer]

OBJECTIVE

To analyse the clinical course and treatment result of lung metastases from breast cancer.

METHODS

122 cases with lung metastases from breast cancer were treated by chemotherapy or chemotherapy plus endocrine therapy. Treatment results were assessed according to WHO criteria and survival rate estimated using the life table.

RESULTS

The median time from initial treatment of primary tumour to lung metastases was 22 months. Sites of common consecutive metastases were lung, liver and bone. The overall response rate was 48% with a CR rate of 15%. Compared to non-DDP-encompassing regimen, the CR rate was higher in DDP-based chemotherapy (7% versus 21%, P < 0.05) with a longer median survival time (MST). The PR rate was higher in regimen containing anthracycline (48%) than in that without anthracycline (20%, P < 0.01). The response rate was similar between chemotherapy and chemotherapy plus endocrine therapy (P > 0.05). No difference in MST was observed between patients receiving anthracycline- and non-anthracycline-encompassing regimens. The 1-,3-,5- and 10-year survival rate was 77%, 22%, 11% and 10%, respectively. The size of primary tumour, the length of disease-free interval, the number of lung metastases may provide additional information for predicting patients' survival after treatment of lung metastases.

CONCLUSION

Combination chemotherapy, especially DDP-based chemotherapy may prolong survival time of patients with lung metastases from breast cancer.

Defective prohormone processing and altered pancreatic islet morphology in mice lacking active SPC2

The prohormone convertase SPC2 (PC2) participates in the processing of proinsulin, proglucagon, and a variety of other neuroendocrine precursors, acting either alone or in conjunction with the structurally related dense-core granule convertase SPC3 (PC3/PC1). We have generated a strain of mice lacking active SPC2 by introducing the neomycin resistance gene (Neor) into the third exon of the mSPC2 gene. This gene insertion results in the synthesis of an exon 3-deleted form of SPC2 that does not undergo autoactivation and is not secreted. The homozygous mutant mice appear to be normal at birth. However, they exhibit a small decrease in rate of growth. They also have chronic fasting hypoglycemia and a reduced rise in blood glucose levels during an intraperitoneal glucose tolerance test, which is consistent with a deficiency of circulating glucagon. The processing of proglucagon, prosomatostatin, and proinsulin in the alpha, delta, and beta cells, respectively, of the pancreatic islets is severely impaired. The islets in mutant mice at 3 months of age show marked hyperplasia of alpha and delta cells and a relative diminution of beta cells. SPC2-defective mice offer many possibilities for further delineating neuroendocrine precursor processing mechanisms and for exploring more fully the physiological roles of many neuropeptides and peptide hormones.

Expression of soluble, active human macrophage colony stimulating factor in Escherichia coli

Human macrophage colony stimulating factor (M-CSF) has been successfully overexpressed in Escherichia coli AD494 (DE3) with an expression level of approximate 26% of the total cellular proteins. The truncated human M-CSF gene encoding the amino-terminal 149 amino acids was subcloned into the prokaryotic expression vector pET11d under the control of the inducible T7 promoter. Nearly 40% of the recombinant protein was in the soluble fraction which showed obvious stimulating effects on mouse macrophage colony formation and had an M-CSF specific activity of approximately 1 x 10(6) units/mg soluble protein.

Urine and urine-derived compounds induce c-fos mRNA expression in accessory olfactory bulb

Soiled bedding from male mice induced c-fos mRNA expression in the accessory olfactory bulb (AOB) and main olfactory bulb (MOB) of female mice. The increase observed in the AOB, but not the MOB, was dependent on the presence of the vomeronasal organ (VNO). Male urine alone also increased c-fos mRNA expression in the AOB. The urine-derived compounds dehydro-exo-brevicomin (DHB) and sec-butyl-dihydrothiazole (SBT) in combination with major urinary protein (MUP) induced significantly greater c-fos mRNA expression in the AOB than in the MOB. The results indicate that compounds derived from male urine are detected at the AOB and suggest that specific urinary compounds play an important role in AOB-mediated reproductive events.

Renaturation, purification, and characterization of human plasminogen activator inhibitor type 2 (PAI-2) accumulated at high level in Escherichia coli

Plasminogen activator inhibitor 2 (PAI-2) is an important regulator of plasminogen activation, which inhibits both tissue-type plasminogen activator (tPA) and urokinase-type plasminogen activator (uPA). In this study we have developed a high-level expression system by inserting a modified PAI-2 gene downstream of the T7 promoter. The expression level of recombinant PAI-2 amounted to 55-60% of total microbial protein. By efficient renaturation and one-step purification, the recombinant protein was purified to homogeneity. The specific activity and yield of recombinant PAI-2 reached 33,000 IU/mg and 10 mg per gram wet weight of Escherichia coli cells, respectively. The second-order rate constant for uPA was 2.6-2.8 x 10(6) M(-1) x s(-1).

[Influence of antisense N-ras 1 gene on smooth muscle cell proliferation after arterial injury]

OBJECTIVES

To develop a new way to prevent the process of restenosis after arterial injury, we transfered the recombinant antisense N-ras 1 gene to the iliac arteries of rabbits after injury and studied the influence of gene therapy with antisense N-ras 1 on the vascular segment.

METHODS

The constructed recombinant antisense N-ras 1 gene to deliver into the iliac arteries of rabbits after injury. The rabbits were randomly divided into gene therapy group, vector group, and sense N-ras 1 control. The segments of treatment rabbits were analysed by angiography of vessels, pathological study, Northern blotting, and Western blotting technique.

RESULTS

The minimum angiographic lumen diameter measured during gene therapy and at follow-up, for the gene therapy group (at 4 weeks) was 0.80 +/- 0.10mm and the vector control 0.35 +/- 0.13mm (P < 0.01). Histologically, the area of neointima measured, for gene the therapy group (at 4 weeks) was 0.43 +/- 0.05mm2, and the vector control group 0.82 +/- 0.03mm2 (P < 0.01). By using Northern blotting and Western blotting technique, we found that cell's ras mRNA of the vessel segments of gene local delivery was significantly lower than that of the control. Cell's p21 was significantly lower than that of the control.

CONCLUSIONS

The antisense N-ras 1 inhibites VSMC proliferation. The result implicates the potential value in future gene therapy of restenosis.

PACE4: a subtilisin-like endoprotease with unique properties

PACE4 is one of the neuroendocrine-specific mammalian subtilisin-related endoproteases believed to function in the secretory pathway. The biosynthesis and secretion of PACE4 have been studied using transfected neuroendocrine and fibroblast cell lines. as well as primary pituitary cultures. ProPACE4 (approx. 106 kDa) is cleaved intracellularly before secretion of PACE4 (approx. 97 kDa); the N-terminal propeptide cleavage is accelerated in a truncated form of PACE4 lacking the Cys-rich C-terminal region (PACE4s). Neither PACE4 nor PACE4s is stored in regulated neuroendocrine secretory granules, whereas pro-opiomelanocortin-derived peptides and prohormone convertase I enter the regulated secretory pathway efficiently. The relatively slow cleavage of the proregion of proPACE4 in primary anterior pituitary cells, followed by rapid secretion of PACE4, is similar to the results for proPACE4 in transfected cell lines. The enzyme activity of PACE4 is distinct from furin and prohormone convertases, both in the marked sensitivity of PACE4 to inhibition by leupeptin and the relative insensitivity of PACE4 to inhibition by Ca2+ chelators and dithiothreitol; PACE4 is not inhibited by the alpha1-antitrypsin Portland variant that is very potent at inhibiting furin. The unique biosynthetic and enzymic patterns seen for PACE4 suggest a role for this neuroendocrine-specific subtilisin-like endoprotease outside the pathway for peptide biosynthesis.

[Evaluation of the function of palatine tonsil with regard to phagocytosis]

Trypan blue and Indian ink made in Fuzhou as vital staining dyes were injected into the abdominal cavities of rabbits. Nine days later, the tonsil, thymus, spleen and lymph nodes were examined. Numerous pigment granules were observed in the macrophages of the spleen and lymph node. However, no phagocytosis of pigment granules was found in the palatine tonsil and thymus. It indicated that the function of palatine tonsil as a lymph organ is to contact exogenous antigens and to take part in immune response. It is important for children, especially infants, to establish a complete immune mechanism. The Tonsils reach their maximum development in childhood and thereafter decline. Once the palatine tonsils become chronic foci, surgical removal of the diseased tonsils is necessary.

[Loss of p16 gene in bladder cancer and genitourinary carcinoma cell lines]

To determine whether p16, a novel antioncogene, is altered in human bladder cancer and urogenital carcinoma cell lines, we examined a series of 10 primary bladder cancer and 4 urogenital carcinoma cell lines (BIU-87, EJ, GRC and PC-3M) by southern blot. Two cases of 10 primary bladder cancer and EJ, BIU-87 PC-3M had homozygous deletion of p16, and 2 cases of 10 primary bladder cancer had loss of heterozygous. Loss of p16 may provide an additional growth advantage and carcinogenesis.

[Molecular bypass, the application of VEGF to gene therapy of limb ischemia]

OBJECTIVE

To investigate the feasibility of using VEGF gene directly for treating limb ischemia.

METHODS

The human VEGF165 cDNA was cloned into the eukaryotic expression vector pcDNA3 under the control of cytomegalovirus immediate-early promoter/enhancer. When gene suture was used, the recombinant plasmid was transferred into the hindlimb's adductor of rat, of which the distal extreme of external iliac artery was ligated and the femoral artery was completely excised. With RT-PCR, Western blot, immunohistochemistry analysis, and angiography, the expression and biological effects of VEGF gene in experimental animals were investigated.

RESULTS

Seven days after initiation of therapy, the transcription and expression of VEGF gene in experimental group were significantly higher than those of control groups. The results from angiography, feet temperature measuring and observation of clinical symptom showed that the transfer of VEGF gene can stimulate the formation of focal neovessles, establish colleteral circulation, augment blood perfusion, and ameliorate distal limb necrosis.

CONCLUSION

These findings reveal that the "molecular bypass" using VEGF gene may represent a potential therapeutic modality for treating tissue ischemia.

Complement subcomponent C1q modulation of TNF-alpha binding to L929 cells for enhanced TNF-mediated cytotoxicity

Complement subcomponent C1q has been recently implicated in the modulation of autocrine binding of TNF-alpha to murine macrophages for induction of nitric oxide synthase. In the present study, the putative role of C1q in increasing TNF-alpha binding to L929 cells to mediate cytotoxicity was explored. TNF-sensitive L929 cells (L929-S) had higher total endogenous cellular and surface C1q levels and bound correspondingly more phycoerythrin-labelled rTNF-alpha (PE-TNF) than did a TNF-resistant L929 variant (L929-R). Pretreatment of L929-S with soluble C1q increased their sensitivity to TNF-mediated cytotoxicity coincident with increased binding of PE-TNF, but similar treatment of L929-R had no effect. Pretreatment of L929-S with an inhibitor of C1q secretion, 3,4 dehydro-D,L-proline (DHP), resulted in a decrease in their TNF-mediated cytotoxicity, as well as reduced binding of PE-TNF. Subsequent exposure of DHP-treated L929-S with exogenous soluble C1q restored their TNF-mediated cytotoxicity and binding of PE-TNF. These results provide evidence for the modulation of TNF-alpha binding to TNF sensitive tumour targets L929 by either endogenously synthesized or exogenously added C1q to promote TNF-mediated cytotoxicity by mechanisms which remain to be elucidated.

Translation initiation region plays an important role in the expression of human thrombopoietin in Escherichia coli

A mutant human thrombopoietin (TPO) gene with a modified translation initiation region (TIR) sequence was created by site-specific mutagenesis based on the PCR technique. This mutant TPO gene encoded the same amino acid sequence as wild-type TPO gene. The wild-type TPO gene was expressed in E. coli with very low efficiency. The mutant TPO gene could reach an expression level of up to 10% of total cellular proteins in E. coli, which was much higher than the wild-type gene. The recombinant protein was mainly in the form of inclusion body which could acquire in vitro activities of human thrombopoietin after refolding.

Chromogranin A processing and secretion: specific role of endogenous and exogenous prohormone convertases in the regulated secretory pathway

Chromogranins A and B and secretogranin II are a family of acidic proteins found in neuroendocrine secretory vesicles; these proteins contain multiple potential cleavage sites for proteolytic processing by the mammalian subtilisin-like serine endoproteases PC1 and PC2 (prohormone convertases 1 and 2), and furin. We explored the role of these endoproteases in chromogranin processing in AtT-20 mouse pituitary corticotropes. Expression of inducible antisense PC1 mRNA virtually abolished PC1 immunoreactivity on immunoblots. Chromogranin A immunoblots revealed chromogranin A processing, from both the NH2 and COOH termini, in both wild-type AtT-20 and AtT-20 antisense PC1 cells. After antisense PC1 induction, an approximately 66-kD chromogranin A NH2-terminal fragment as well as the parent chromogranin A molecule accumulated, while an approximately 50 kD NH2-terminal and an approximately 30 kD COOH-terminal fragment declined in abundance. Chromogranin B and secretogranin II immunoblots showed no change after PC1 reduction. [35S]Methionine/cysteine pulse-chase metabolic labeling in AtT-20 antisense PC1 and antisense furin cells revealed reciprocal changes in secreted chromogranin A COOH-terminal fragments (increased approximately 82 kD and decreased approximately 74 kD forms, as compared with wild-type AtT-20 cells) indicating decreased cleavage, while AtT-20 cells overexpressing PC2 showed increased processing to and secretion of approximately 71 and approximately 27 kD NH2-terminal chromogranin A fragments. Antisense PC1 specifically abolished regulated secretion of both chromogranin A and beta-endorphin in response to the usual secretagogue, corticotropin-releasing hormone. Moreover, immunocytochemistry demonstrated a relative decrease of chromogranin A in processes (where regulated secretory vesicles accumulate) of AtT-20 cells overexpressing either PC1 or PC2. These results demonstrate that chromogranin A is a substrate for the endogenous endoproteases PC1 and furin in vivo, and that such processing influences its trafficking into the regulated secretory pathway; furthermore, lack of change in chromogranin B and secretogranin II cleavage after diminution of PCl suggests that the action of PC1 on chromogranin A may be specific within the chromogranin/secretogranin protein family.

Peptide biosynthetic processing: distinguishing prohormone convertases PC1 and PC2

To determine whether manipulation of time, temperature and intragranular pH could be used to distinguish the actions of two subtilisin-related endoproteases, PC1 and PC2, in peptide biosynthesis, the biosynthetic processing of proneuropeptide Y (proNPY) and proopiomelanocortin (POMC) was examined in pituitary cell lines. AtT-20 cells express PC1 and POMC endogenously; stably transfected AtT-20 lines expressing NPY or PC2 were studied. GH3 cells express PC2 endogenously; NPY-expressing GH3 transfectants were investigated. PC1 mediated rapid processing of NPY and POMC; PC1-dependent cleavages were relatively insensitive to 20 degrees C blockade (which arrests secretory pathway transport at the trans-Golgi network) and do not require an acidic intracellular compartment (as in secretory granules). PC2 mediated much slower processing of proNPY and POMC which was totally blocked at 20 degrees C and required an acidic intracellular compartment. Thus, kinetics, abolition of intracellular pH gradients, and incubation at reduced temperatures can be used to distinguish PC1 and PC2 actions in neuroendocrine cells.

IFN-alpha beta reconstitutes the deficiency in lipid A-activated AKR macrophages for nitric oxide synthase

AKR mouse peritoneal macrophages (PM) were previously found to have a defect in their response to lipid A for nitric oxide (NO)-mediated tumor cytotoxicity, which was related to a lower level of C1q synthesis and reconstituted by exogenous IFN-gamma or C1q. We used AKR-PM as a model to further define the role of IFN-alpha beta in modulation of induction of macrophage nitric oxide synthase (NOS) in response to lipid A. Studies have revealed that AKR-PM produced a significantly lower level of IFN-alpha beta than responsive C3H-PM in response to lipid A. AKR-PM failed to increase NOS mRNA synthesis and NO generation when exposed to lipid A, although they had normal levels of TNF-alpha bioactivity and mRNA expression. This partial deficiency of AKR-PM to lipid A stimulation was reconstituted completely by exogenous IFN-alpha beta for both synthesis of NOS mRNA and release of NO. The failure of AKR-PM to produce NOS to lipid A stimulation appears to be related to reduced secretion of IFN-alpha beta and the resultant failure to express TNF-alpha type II receptor (TNF-RII) mRNA, which in turn decreases TNF-alpha binding to its receptor for autocrine induction of NOS. Insufficient synthesis and secretion of endogenous IFN-alpha beta may be the primary reason for AKR-PM refractoriness to induction of NOS in response to lipid A. furthermore, the close correlation between lack of IFN-alpha beta secretion and decreased TNF-RII mRNA synthesis may implicate a critical role for IFN-alpha beta in the upregulation of macrophage TNF-RII receptor expression for autocrine induction of NOS during lipid A stimulation.

IFN-alpha beta reconstitutes the deficiency in lipid A-activated AKR macrophages for nitric oxide synthase

AKR mouse peritoneal macrophages (PM) were previously found to have a defect in their response to lipid A for nitric oxide (NO)-mediated tumor cytotoxicity, which was related to a lower level of C1q synthesis and reconstituted by exogenous IFN-gamma or C1q. We used AKR-PM as a model to further define the role of IFN-alpha beta in modulation of induction of macrophage nitric oxide synthase (NOS) in response to lipid A. Studies have revealed that AKR-PM produced a significantly lower level of IFN-alpha beta than responsive C3H-PM in response to lipid A. AKR-PM failed to increase NOS mRNA synthesis and NO generation when exposed to lipid A, although they had normal levels of TNF-alpha bioactivity and mRNA expression. This partial deficiency of AKR-PM to lipid A stimulation was reconstituted completely by exogenous IFN-alpha beta for both synthesis of NOS mRNA and release of NO. The failure of AKR-PM to produce NOS to lipid A stimulation appears to be related to reduced secretion of IFN-alpha beta and the resultant failure to express TNF-alpha type II receptor (TNF-RII) mRNA, which in turn decreases TNF-alpha binding to its receptor for autocrine induction of NOS. Insufficient synthesis and secretion of endogenous IFN-alpha beta may be the primary reason for AKR-PM refractoriness to induction of NOS in response to lipid A. furthermore, the close correlation between lack of IFN-alpha beta secretion and decreased TNF-RII mRNA synthesis may implicate a critical role for IFN-alpha beta in the upregulation of macrophage TNF-RII receptor expression for autocrine induction of NOS during lipid A stimulation.

High-level expression of active human plasminogen activator inhibitor type 1 (PAI-1) in E. coli

Plasminogen activator inhibitor 1 (PAI-1) is an important regulator of plasminogen activation, which inhibits both tissue-type plasminogen activator (tPA) and urokinase-type plasminogen activator (uPA). The DNA sequence encoding mature PAI-1 protein was inserted into an inducible expression vector. This gene was highly expressed to produce a soluble active protein in E. coli cells. The amount of the recombinant protein was up to 20% of total cellular protein. By efficient purification with a yield of about 15-20%, the recombinant protein could be purified to homogeneity with its specific activity up to 6.1 x 10(4) (uPA) IU/mg. Its inhibitory activity declined during incubation at 37 degrees C with a half life of about 2 hr.

Autocrine induction of macrophage synthesis of complement subcomponent C1q by endogenous interferon-alpha/beta

Peritoneal macrophages (M phi) constitutively synthesize and secrete interferon-alpha (IFN-alpha) and IFN-beta, as well as complement subcomponent C1q. Because exogenous interferon-gamma (IFN-gamma) stimulates Mø synthesis of C1q, our purpose was to determine if endogenous secretion of IFN-alpha/beta regulated the constitutive level of endogenous C1q mRNA synthesis in an autocrine fashion. Both exogenous IFN-alpha and IFN-beta effectively substituted for IFN-gamma in stimulating M phi C1q mRNA expression in a dose-dependent fashion by northern blot analysis. Neutralizing anti-INF-alpha/beta antibodies inhibited M phi constitutive C1q mRNA synthesis by approximately twofold and abrogated the feedback stimulatory effects of exogenous C1q on C1q mRNA expression. Paraffin oil-elicited inflammatory M phi displayed distinctively different constitutive levels of C1q mRNA expression from thioglycollate brothelicited M phi, which was correlated with their relative levels of secretory IFN-alpha/beta by ELISA. Exogenous IFN-alpha/beta also restored C1q mRNA synthesis of AKR mouse M phi with low constitutive C1q mRNA expression. The cumulative results support the concept that constitutive synthesis of C1q by M phi is regulated by the endogenous synthesis and secretion of IFN-alpha/beta, which appears to act in an autocrine fashion.

Elevated levels of 2',5'-linked oligoadenylate-dependent ribonuclease L occur as an early event in colorectal tumorigenesis

RNA decay in IFN-treated cells is controlled by 2'5'-linked oligoadenylate (2-5A)-dependent RNase (RNase L), a uniquely regulated endoribonuclease that requires short 5'-phosphorylated, 2-5A for its activity. Because RNase L is also implicated in the regulation of cell proliferation, we monitored its expression in colorectal adenocarcinomas and noncancerous polyps from familial adenomatous polyposis patients. Elevated levels of RNase L mRNA and activity were found in 17 of 20 tumors compared with corresponding normal mucosa. An mAb against RNase L revealed elevated amounts of this RNase in sections of the tumors, largely in the base of the villi. The occurrence of elevated levels of RNase L seems to be an early event in colorectal tumorigenesis, suggesting that control of RNA turnover is an important step in tumor progression. These data also indicate that regulating RNase L activity may be a useful strategy in treating colorectal carcinomas.

Exogenous interferon-gamma induces endogenous synthesis of interferon-alpha and -beta by murine macrophages for induction of nitric oxide synthase

Murine macrophages (M phi) are activated either by interferon-gamma (IFN-gamma) or interferon-alpha/beta (IFN-alpha/beta) in combination with bacterial lipopolysaccharide (LPS) to induce synthesis of tumor necrosis factor alpha (TNF-alpha) and nitric oxide synthase (iNOS) mRNA synthesis for generation of tumor cytotoxic nitric oxide (NO). In the present study, the effect of exogenous IFN-gamma on the induction of endogenous mRNA synthesis and secretion of IFN-alpha/beta by murine M phi was investigated. Neutralizing antibodies to IFN-alpha/beta reversed TNF-alpha and NOS mRNA synthesis, as well as nitric oxide (NO)-mediated tumor cytotoxicity. Quantitative reverse transcription polymerase chain reaction (RT-PCR) revealed that treatment of M phi with IFN-gamma induced increases in both IFN-alpha and IFN-beta mRNA synthesis by approximately 2-fold and 10-fold, respectively, which corresponded to a 2-fold increase in secretion of IFN-alpha/beta by ELISA. These data indicate that exogenous IFN-gamma induces endogenous synthesis and secretion of IFN-alpha/beta by M phi, which appears to act in concert with endogenously synthesized TNF-alpha for the autocrine induction of NOS mRNA synthesis.

Structural elements that direct specific processing of different mammalian subtilisin-like prohormone convertases

PC1 and PC2 are two important subtilisin-like prohormone convertases (PC) that undergo differential endoproteolytic processing steps and sequentially mediate proopiomelanocortin (POMC) processing. To investigate the structural elements directing the processing of different PCs, we constructed a series of mutant and chimeric PC proteins and expressed them in cell lines with different patterns of expression of endogenous PCs: AtT-20, hEK293, and hLoVo cells. The COOH-terminally truncated PC1 underwent efficient proregion cleavage and rapid secretion in all three cell lines, while proregion cleavage and secretion were completely blocked in an active-site mutant of PC1. The truncated PC1 produced dramatic changes in POMC processing in AtT-20 cells. PC2 with the potential oxyanion hole Asp residue changed to Asn was processed and altered several aspects of POMC processing in a manner similar to that of wild-type PC2. PC1 protein with its proregion substituted with that of furin was cleaved after its proregion, producing active PC1 enzyme. A similar furin/PC2 fusion protein underwent proregion cleavage at low efficiency. By contrast, when the proregions of PC1 and PC2 were substituted with one another, both fusion proteins failed to cleave the foreign prosequences, were unable to undergo oligosaccharide maturation, and remained in the ER. Although inactive PC mutants could theoretically function as dominant negatives, none interfered with the processing of endogenous active PCs or with POMC processing. We conclude that the COOH-terminal of PC1 plays an important role in the routing or storage of PC1, the proregions of these PC proteins are replaceable in a molecule-specific manner, removal of proregion is essential for routing and for endoproteolytic activity, and the role of the potential oxyanion hole in PC2 is still unclear.

Adenovirus mediated gene transfer of vascular smooth muscle cells and endothelial cells in vitro

Introducing foreign gene(s) into vascular smooth muscle cells (VSMCs) and endothelial cells (ECs) is the pre-requirement of gene therapy for cardiovascular diseases. We have explored the use of adenoviral vectors (Adv-CMV/LacZ) to transfer LacZ gene into cultured VSMCs and ECs. Our results demonstrated that adenoviral vectors transferred foreign gene into VSMCs and ECs high-efficiently with dose-dependent response pattern. The frequencies of transfection reached 100% at the viral titer of 10(9) pfu/ml. Comparing the sensitivities of VSMCs and ECs to adenoviral vectors, we found that ECs were more sensitive than VSMCs, of which the frequencies of transfection in ECs reached 80% while in VSMCs only 40% for 8 hrs after transfection. In addition, the transfection of ECs and VSMCs with adenoviral vectors was partly blocked by monoclonal antibodies to Fiber and Core protein of the adenoviral capsid, but not by monoclonal antibody to Hexon protein. It is suggested transfection of ECs and VSMCs with adenovirus vectors is mediated by Fiber or Core protein of adenoviral capsid proteins.

Expression of human plasminogen activator inhibitor-2 in the baculovirus expression system

A cDNA coding for human plasminogen activator inhibitor-2 (PAI-2) was transferred into the genome of Autographa californica nuclear polyhedrosis virus adjacent to the polyhedrin promoter. Cells infected with recombinant virus synthesized a 43-kDa PAI-2 protein, the majority of which was secreted. The recombinant PAI-2 was identical to native PAI-2 purified from human placenta with respect to interaction with polyclonal antibody and inhibition of urokinase-type plasminogen activator.

Endoproteolytic processing of proopiomelanocortin and prohormone convertases 1 and 2 in neuroendocrine cells overexpressing prohormone convertases 1 or 2

AtT-20 mouse corticotrope tumor cell lines overexpressing the prohormone convertases PC1 or PC2 were established and used to examine prohormone and prohormone convertase biosynthetic processing. On a molar basis, wild-type AtT-20 cells synthesize about 20% as much PC1 as the endogenous prohormone, proopiomelanocortin (POMC). Kinetic, oligosaccharide, and temperature blockade analyses established that proPC1 is converted to PC1 in the endoplasmic reticulum at a rate independent of the level of PC1 or PC2 expression. In contrast, proPC2 is converted to PC2 primarily in a post-trans-Golgi compartment. PC1 is further shortened from its COOH-terminal end in a post-trans-Golgi compartment in a step that is accelerated at higher levels of PC1 expression, but unaltered by PC2 overexpression. The initial steps in POMC processing are speeded up by overexpression of PC1, and overexpression of PC1 leads to more extensive cleavage of POMC to smaller products. However, even when the rate of PC1 synthesis exceeds that for POMC by 2-fold, PC1 does not cleave the Lys-Lys or Arg-Lys bonds cleaved upon overexpression of PC2.

Intrinsic molecular activities of the interferon-induced 2-5A-dependent RNase

2-5A-dependent RNase (RNase L), a unique endoribonuclease that requires 5'-phosphorylated 2',5'-linked oligoadenylates (2-5A), functions in the molecular mechanism of interferon action. Because this enzyme is present at very low levels in nature, characterization and analysis have been limited. The molecular cloning of human, 2-5A-dependent RNase cDNA has facilitated its expression to high levels in insect cells by infecting with recombinant baculovirus. To determine the properties of the enzyme in the absence of other proteins, the recombinant 2-5A-dependent RNase was purified to homogeneity. The purified enzyme migrated as a monomer upon gel filtration in the absence of activator and showed highly specific, 2-5A-dependent RNase activity. The precise activator requirements were determined by stimulating the purified enzyme with a variety of 2',5'-linked oligonucleotides. The activated enzyme was capable of cleaving poly(rU) and, to a lesser extent, poly(rA), to sets of discrete products ranging from between 4 and 22 nucleotides in length. Reduced rates of 2-5A-dependent RNA cleavage were observed even after removal of ATP and chelation of divalent cations. However, optimal RNA cleavage rates required the presence of either manganese or magnesium and ATP.

Regulation of interferon-alpha-inducible cellular genes in human immunodeficiency virus-infected monocytes

Cellular mechanisms that control susceptibility to opportunistic infection in human immunodeficiency virus (HIV)-infected individuals remain poorly understood. HIV may induce certain cellular genes that restrict HIV replication and protect cells against other superinfecting viral pathogens. Indeed, HIV-infected monocytes resist infection by vesicular stomatitis virus (VSV). HIV-induced VSV interference in monocytes increases with time after HIV infection. Such interference was evident 6 h after HIV infection and reached maximal levels at 14 days. Monocytotropic but not T cell-tropic HIV strains elicited these effects, signaling a requirement for viral entry and/or replication. Viral interference was independent of interferon (IFN) and was unaffected by addition of neutralizing IFN-alpha and -beta antibodies. The well-described IFN-alpha-inducible antiviral pathways were examined to determine their relationship to the cellular mechanism(s) underlying VSV interference. HIV and IFN-alpha both induced the expression of 2-5A synthetase and Mx gene. In contrast, the guanylate-binding protein (GBP), 6-16, and 9-27 cellular genes were up-regulated by IFN-alpha but not HIV. MxA was detected in HIV-infected monocytes but not in uninfected monocytes. The association between Mx expression and resistance to VSV, coupled with previously described anti-VSV activities by human MxA, suggested that Mx may be an effector molecule for the HIV-induced anti-VSV activities. These results, taken together, suggest that HIV can induce antiviral cellular gene expression, independent of IFN.

Transport of BC1 RNA in hypothalamo-neurohypophyseal axons

Ample evidence indicates that in nerve cells, several individual proteins are locally synthesized in postsynaptic domains in dendrites. By contrast, axonal terminals, at least in mammals, are generally thought to lack protein synthetic capacity. However, axonal nerve endings of the hypothalamo-neurohypophyseal tract have recently been shown to contain mRNAs encoding vasopressin, oxytocin, dynorphin, and neurofilament. In this report, we identify BC1 RNA, a small RNA polymerase III transcript that is specifically expressed in neurons, in hypothalamo-neurohypophyseal axons. BC1 RNA has previously been shown to be located in somatic and dendritic domains of various types of neurons in the rat nervous system. Here we present evidence to show that BC 1 RNA, like several neuropeptide mRNAs, is axonally transported from magnocellular hypothalamic neurons to neurosecretory nerve endings in the posterior pituitary. BC1 RNA, which has been reported to be a component of a ribonucleoprotein particle, is thus colocalized with dendritic mRNAs in dendritic domains and with axonal mRNAs in axonal domains, respectively. Such colocalization is indicative of functional interactions of BC1 RNA with those mRNAs that are targeted to extrasomatic domains of nerve cells.

A dominant negative mutant of 2-5A-dependent RNase suppresses antiproliferative and antiviral effects of interferon

2-5A-dependent RNase is the terminal factor in the interferon-regulated 2-5A system thought to function in both the molecular mechanism of interferon action and in the general control of RNA stability. However, direct evidence for specific functions of 2-5A-dependent RNase has been generally lacking. Therefore, we developed a strategy to block the 2-5A system using a truncated form of 2-5A-dependent RNase which retains 2-5A binding activity while lacking RNase activity. When the truncated RNase was stably expressed to high levels in murine cells, it prevented specific rRNA cleavage in response to 2-5A transfection and the cells were unresponsive to the antiviral activity of interferon alpha/beta for encephalomyocarditis virus. Remarkably, cells expressing the truncated RNase were also resistant to the antiproliferative activity of interferon. The truncated RNase is a dominant negative mutant that binds 2-5A and that may interfere with normal protein-protein interactions through nine ankyrin-like repeats.

[Morphology of right ventricle and hemodynamics in pulmonary atresia with intact ventricular septum]

Cardiac catheterization and angiography were performed in 31 patients with PA/IVS to evaluate the morphology of RV and hemodynamics. The age of patients ranged from 1 day to 39 month (mean 4.7 month). The patients were divided into three groups: mild (19.4%), moderate (64.5%) and severe (16.1%) RV hypoplasia, according to the degree of tricuspid valve and right ventricular hypoplasia. Seven of the 31 patients (22.6%) had right ventricular myocardial sinusoid-coronary artery fistula. The right and left ventricular pressures in 26 patients were measured simultaneously. The right ventricular pressures were supra-systemic in 18 patients (69.2%), systemic in 6 (23.1%), less than systemic pressures in 2 (7.7%); the others were PA/IVS with ASD(6 patients), PFO (25), PDA (25). Palliative and definitive operations were performed on 22 patients. The results show that determining the morphology of RV and the hemodynamics before operation is helpful in selecting appropriate operation for lowering the operative mortality.

Expression cloning of 2-5A-dependent RNAase: a uniquely regulated mediator of interferon action

2-5A-dependent RNAase, an interferon-induced enzyme that is activated by 5'-phosphorylated, 2',5'-linked oligoadenylates (2-5A), is implicated in both the molecular mechanisms of interferon action and the fundamental control of RNA stability in mammalian cells. Here we report the expression cloning and analysis of murine and human 2-5A-dependent RNAases. The 2-5A binding properties and RNAse activities of recombinant and naturally occurring forms of 2-5A-dependent RNAase were identical. Interferon induction of 2-5A-dependent RNAse expression was demonstrated by measuring the mRNA levels in cells treated with interferon and cycloheximide. Analysis of aligned murine and human 2-5A-dependent RNAse sequences revealed several intriguing features, including similarity to RNAase E, which is implicated in the control of mRNA stability in E. coli. Interestingly, a duplicated phosphate-binding loop motif was determined by deletion analysis and site-directed mutagenesis to function in the binding of 2-5A.

Targeting RNA for degradation with a (2'-5')oligoadenylate-antisense chimera

Antisense oligonucleotides hold considerable promise both as research tools for inhibiting gene expression and as agents for the treatment of a myriad of human diseases. However, targeted destruction of RNA has been difficult to achieve in a versatile, efficient, and reliable manner. We have developed an effective strategy for cleaving unique RNA sequences with 2-5A-dependent RNase, an endoribonuclease that mediates inhibitory effects of interferon on virus infection and is activated by 5'-phosphorylated 2'-5'-linked oligoadenylates known as 2-5A [pn5' A2'(p5' A2')mp5'A], resulting in the cleavage of single-stranded RNA predominantly after UpUp and UpAp sequences. To direct 2-5A-dependent RNase to cleave unique RNA sequences, p5' A2' p5' A2'p5'A was covalently linked to an antisense oligonucleotide to yield a chimeric molecule (2-5A:AS). The antisense oligonucleotide component of 2-5A:AS bound a specific RNA sequence while the accompanying 2-5A component activated 2-5A-dependent RNase, thereby causing the cleavage of the RNA in the targeted sequence. This strategy was demonstrated by inducing specific cleavage within a modified human immunodeficiency virus type 1 vif mRNA in a cell-free system from human lymphoblastoid cells. Because 2-5A-dependent RNase is present in most mammalian cells, the control of gene expression based on this technology--including therapies for cancer, viral infections, and certain genetic diseases--can be envisioned.

The prohormone convertases PC1 and PC2 mediate distinct endoproteolytic cleavages in a strict temporal order during proopiomelanocortin biosynthetic processing

Two subtilisin-like endoproteases called PC1 and PC2 are distributed in a tissue-specific manner in the pituitary and in the brain. AtT-20 cells and corticotropes of the anterior pituitary express primarily PC1 and perform a limited number of cleavages of the proopiomelanocortin (POMC) precursor during biosynthesis. Melanotropes of the intermediate pituitary express both PC1 and PC2 and perform a more extensive set of cleavages during the biosynthetic processing of POMC. To investigate the role of PC2 in the biosynthetic processing of POMC, AtT-20 mouse corticotropes were stably transfected with a full length PC2 cDNA. The AtT-20 cells expressing PC2 acquired the ability to perform all the additional cleavages seen in the intermediate pituitary, but did not acquire the ability to alpha-N-acetylate the product peptides. The kinetics of the earliest steps in biosynthetic processing were unaltered by the expression of PC2, and the changes due to PC2 expression were seen only in the middle and late steps in biosynthetic processing. Thus, both the identity of the final product peptides and the kinetics of the processing steps in the AtT-20 cells expressing PC2 fit the patterns expected for melanotropes of the intermediate pituitary.