[Comparison of pathogenicity and gene expression profiles between adult Schistosoma japonicum isolated from hilly and marshland and lake regions of Anhui Province]

OBJECTIVE

To compare the differences in pathogenicity and gene expression profiles between adult Schistosoma japonicum isolated from hilly and marshland and lake regions of Anhui Province, so as to provide the scientific evidence for formulating the precise schistosomiasis control strategy in different endemic foci.

METHODS

C57BL/6 mice were infected with cercariae of S. japonicum isolates from Shitai County (hilly regions) and Susong County (marshland and lake regions) of Anhui Province in 2021, and all mice were sacrificed 44 days post-infection and dissected. The worm burdens, number of S. japonicum eggs deposited in the liver, and the area of egg granulomas in the liver were measured to compare the difference in the pathogenicity between the two isolates. In addition, female and male adult S. japonicum worms were collected and subjected to transcriptome sequencing, and the gene expression profiles were compared between Shitai and Susong isolates of S. japonicum. The differentially expressed genes (DEGs) were subjected to Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses.

RESULTS

The total worm burdens [(14.50 ± 3.96) worms/mouse vs. (16.10 ± 3.78) worms/mouse; t = 0.877, P = 0.392], number of female and male paired worms [(4.50 ± 0.67) worms/mouse vs. (5.10 ± 1.45) worms/mouse; t = 1.129, P = 0.280], number of unpaired male worms [(5.50 ± 4.01) worms/mouse vs. (5.60 ± 1.69) worms/mouse; t = 0.069, P = 0.946], number of eggs deposited in per gram liver [(12 116.70 ± 6 508.83) eggs vs. (16 696.70 ± 4 571.56) eggs; t = 1.821, P = 0.085], and area of a single egg granuloma in the liver [(74 359.40 ± 11 766.34) µm² vs. (74 836.90 ± 13 086.12) µm²; t = 0.081, P = 0.936] were comparable between Shitai and Susong isolates of S. japonicum. Transcriptome sequencing identified 584 DEGs between adult female worms and 1 598 DEGs between adult male worms of Shitai and Susong isolates of S. japonicum. GO enrichment analysis showed that the DEGs between female adults were predominantly enriched in biological processes of stimulus response, cytotoxicity, multiple cell biological processes, metabolic processes, cellular processes and signaling pathways, cellular components of cell, organelles and cell membranes and molecular functions of binding and catalytic ability, and KEGG enrichment analysis showed that these DEGs were significantly enriched in pathways of vascular endothelial growth factor signaling, glutathione metabolism, arginine and proline metabolism. In addition, the DEGs between male adults were predominantly enriched in biological processes of signaling transduction, multiple cell biological processes, regulation of biological processes, metabolic processes, development processes and stimulus responses, cellular components of extracellular matrix and cell junction and molecular functions of binding and catalytic ability, and these DEGs were significantly enriched in pathways of Wnt signaling, Ras signaling, natural killer cells-mediated cytotoxicity, extracellular matrix-receptor interactions and arginine biosynthesis.

CONCLUSIONS

There is no significant difference in the pathogenicity between S. japonicum isolates from hilly and marshland and lake regions of Anhui Province; however, the gene expression profiles vary significantly between S. japonicum isolates.

Assessment of the relationship between a written measure of empathy and an independently rated interview of Motivational Interviewing

Motivational Interviewing (MI) is an evidence-based practice shown to be effective when working with people in treatment for substance use disorders. However, MI is a complex treatment modality optimized by training with feedback. Feedback, assessment and monitoring of treatment fidelity require measurement, which is typically done using audiotaped sessions. The gold standard for such measurement of MI skill has been an audiotaped interview, scored by a rater with a detailed structured instrument such as the Motivational Interviewing Treatment Integrity 2.0 (MITI 2.0) Coding System (Moyers, et al., 2005). The Helpful Responses Questionnaire (HRQ) (Miller, Hedrick, & Orlofsky, 1991) is a pen-and-paper test of empathy (a foundational MI skill) that does not require an audiotaped session. A randomized trial of three different regimens for training counselors in MI (live supervision using Teleconferencing, Tape-based supervision and Workshop only) (Smith et al., 2012) offered the opportunity to evaluate the performance of the HRQ as a measure of MI ability, compared to the several MITI 2.0 global scores and subscales. Participants were counselors (N=97) working at community-based substance use treatment programs, whose MI proficiency was measured at four time points: baseline (before an initial 2-day MI workshop), post-workshop, 8weeks post-workshop (i.e., post-supervision), and 20weeks post-workshop with both MITI 2.0 and HRQ. HRQ total scores correlated significantly with the Reflection to Question Ratio from the MITI 2.0 at post-workshop (r=0.33), week 8 (r=0.34), and week 20 (r=0.38), and with the Spirit (r=0.32) and Empathy (r=0.32) global scores at week 20. Correlations of HRQ with other MITI 2.0 subscales and time points after workshop were small and not significant. As predicted, HRQ scores differed between training conditions (X²(2)=7.88, p=0.02), with counselors assigned to live supervision achieving better HRQ scores than those in Workshop only. In summary, HRQ is a modestly accurate measure, mainly of the Reflection to Question Ratio, considered a core marker of MI skill. It is sensitive to training effects and may help identify counselors needing more intensive supervision. Given its ease of administration and scoring, HRQ may be a useful marker of MI skill during training efforts.

A sub-set of psychoactive effects may be critical to the behavioral impact of ketamine on cocaine use disorder: Results from a randomized, controlled laboratory study

Efforts to translate sub-anesthetic ketamine infusions into widespread clinical use have centered around developing medications with comparable neurobiological activity, but with attenuated psychoactive effects so as to minimize the risk of behavioral toxicity and abuse liability. Converging lines of research, however, suggest that some of the psychoactive effects of sub-anesthetic ketamine may have therapeutic potential. Here, we assess whether a subset of these effects - the so-called mystical-type experience - mediates the effect of ketamine on craving and cocaine use in cocaine dependent research volunteers. We found that ketamine leads to significantly greater acute mystical-type effects (by Hood Mysticism Scale: HMS), dissociation (by Clinician Administered Dissociative States Scale: CADSS), and near-death experience phenomena (by the Near-Death Experience Scale: NDES), relative to the active control midazolam. HMS score, but not the CADSS or NDES score, was found to mediate the effect of ketamine on global improvement (decreased cocaine use and craving) over the post-infusion period. This is the first controlled study to show that mystical-type phenomena, long considered to have therapeutic potential, may work to impact decision-making and behavior in a sustained manner. These data suggest that an important direction for medication development is the identification of ketamine-like pharmacotherapy that is selectively psychoactive (as opposed to free of experiential effects entirely), so that mystical-type perspectival shifts are more reliably produced and factors lending to abuse or behavioral impairment are minimized. Future research can further clarify the relationship between medication-occasioned mystical-type effects and clinical benefit for different disorders. This article is part of the Special Issue entitled 'Psychedelics: New Doors, Altered Perceptions'.

Activating JAK2 mutants reveal cytokine receptor coupling differences that impact outcomes in myeloproliferative neoplasm

Janus tyrosine kinase 2 (JAK2) mediates downstream signaling of cytokine receptors in all hematological lineages, yet constitutively active JAK2 mutants are able to drive selective expansion of particular lineage(s) in myeloproliferative neoplasm (MPN). The molecular basis of lineage specificity is unclear. Here, we show that three activating JAK2 mutants with similar kinase activities in vitro elicit distinctive MPN phenotypes in mice by differentially expanding erythroid vs granulocytic precursors. Molecularly, this reflects the differential binding of JAK2 mutants to cytokine receptors EpoR and GCSFR in the erythroid vs granulocytic lineage and the creation of unique receptor/JAK2 complexes that generate qualitatively distinct downstream signals. Our results demonstrate that activating JAK2 mutants can differentially couple to selective cytokine receptors and change the signaling repertoire, revealing the molecular basis for phenotypic differences elicited by JAK2 (V617F) or mutations in exon 12. On the basis of these findings, receptor-JAK2 interactions could represent new targets of lineage-specific therapeutic approaches against MPN, which may be applicable to other cancers with aberrant JAK-STAT signaling.

Recent Internet Use and Associations with Clinical Outcomes among Patients Entering Addiction Treatment Involved in a Web-Delivered Psychosocial Intervention Study

The acceptability and clinical impact of a web-based intervention among patients entering addiction treatment who lack recent internet access are unclear. This secondary analysis of a national multisite treatment study (NIDA Clinical Trials Network-0044) assessed for acceptability and clinical impact of a web-based psychosocial intervention among participants enrolling in community-based, outpatient addiction treatment programs. Participants were randomly assigned to 12 weeks of a web-based therapeutic education system (TES) based on the community reinforcement approach plus contingency management versus treatment as usual (TAU). Demographic and clinical characteristics, and treatment outcomes were compared among participants with recent internet access in the 90 days preceding enrollment (N = 374) and without internet access (N = 133). Primary outcome variables included (1) acceptability of TES (i.e., module completion; acceptability of web-based intervention) and (2) clinical impact (i.e., self-reported abstinence confirmed by urine drug/breath alcohol tests; retention measured as time to dropout). Internet use was common (74 %) and was more likely among younger (18-49 years old) participants and those who completed high school (p < .001). Participants randomized to TES (n = 255) without baseline internet access rated the acceptability of TES modules significantly higher than those with internet access (t = 2.49, df = 218, p = .01). There was a near significant interaction between treatment, baseline abstinence, and internet access on time to dropout (χ ²(1) = 3.8089, p = .051). TES was associated with better retention among participants not abstinent at baseline who had internet access (X ²(1) = 6.69, p = .01). These findings demonstrate high acceptability of this web-based intervention among participants that lacked recent internet access.

αKlotho and Chronic Kidney Disease

Alpha-Klotho (αKlotho) protein is encoded by the gene, Klotho, and functions as a coreceptor for endocrine fibroblast growth factor-23. The extracellular domain of αKlotho is cleaved by secretases and released into the circulation where it is called soluble αKlotho. Soluble αKlotho in the circulation starts to decline in chronic kidney disease (CKD) stage 2 and urinary αKlotho in even earlier CKD stage 1. Therefore soluble αKlotho is an early and sensitive marker of decline in kidney function. Preclinical data from numerous animal experiments support αKlotho deficiency as a pathogenic factor for CKD progression and extrarenal CKD complications including cardiac and vascular disease, hyperparathyroidism, and disturbed mineral metabolism. αKlotho deficiency induces cell senescence and renders cells susceptible to apoptosis induced by a variety of cellular insults including oxidative stress. αKlotho deficiency also leads to defective autophagy and angiogenesis and promotes fibrosis in the kidney and heart. Most importantly, prevention of αKlotho decline, upregulation of endogenous αKlotho production, or direct supplementation of soluble αKlotho are all associated with attenuation of renal fibrosis, retardation of CKD progression, improvement of mineral metabolism, amelioration of cardiac function and morphometry, and alleviation of vascular calcification in CKD. Therefore in rodents, αKlotho is not only a diagnostic and prognostic marker for CKD but the enhancement of endogenous or supplement of exogenous αKlotho are promising therapeutic strategies to prevent, retard, and decrease the comorbidity burden of CKD.

Genomic structure of the mouse PP4 gene: a developmentally regulated protein phosphatase

Protein phosphatases play important roles in the control of various cellular processes. Here, we report the cloning and characterization of the murine cDNA and genomic DNA encoding the serine/threonine protein phosphatase 4 (PP4), also called PPX. While the nucleotide sequences of murine and human PP4 are distinct, their amino acid sequences are identical. We have analyzed the protein, cDNA and genomic PP4 sequences to provide insight into the structure, function and potential regulation of PP4. Genomic Southern blots demonstrated the conservation of PP4 across species. Using Northern blotting and in situ hybridization, we have examined the expression of PP4 in murine embryos and adult tissues. In adult tissues, PP4 was expressed at high levels in the testis, kidney, liver, and lung, and at lower levels in virtually all tissues. PP4 was differentially expressed in murine embryos at different developmental stages, suggesting that PP4 is a developmentally regulated protein phosphatase.

Identification of a candidate human neurohematopoietic stem-cell population

It was recently reported that transplantation of clonally derived murine neurosphere cells into sublethally irradiated allogeneic hosts leads to a donor-derived hematopoietic reconstitution. The confirmation of the existence of a common neurohematopoietic stem cell in the human brain will have a significant effect on stem cell research and on clinical transplantation. Here, it is demonstrated that the human fetal brain contains separate but overlapping epidermal growth factor (EGF)-responsive and basic fibroblast growth factor (FGF-2)-responsive neural stem cells. The majority (> 85%) of cells within these EGF- and/or FGF-2-generated neurospheres express characteristic neural stem/progenitor cell markers including nestin, EGF receptor, and FGF-2 receptor. These neural stem cells can be continuously passaged in vitro, and demonstrate a constant 20-fold expansion in every passage for up to the fifth passage (the longest period that has been carried out in the authors' laboratory). These neural stem cells are multipotential for neurons, astrocytes, and oligodendrocytes. After transplantation into SCID-hu mice, all neural stem cells, regardless of passages, culture conditions, and donors, are able to establish long-term hematopoietic reconstitution in the presence of an intact human bone marrow microenvironment.

Dopamine acutely stimulates Na+/H+ exchanger (NHE3) endocytosis via clathrin-coated vesicles: dependence on protein kinase A-mediated NHE3 phosphorylation

Dopamine (DA) is a key hormone in mammalian sodium homeostasis. DA induces natriuresis via acute inhibition of the renal proximal tubule apical membrane Na(+)/H(+) exchanger NHE3. We examined the mechanism by which DA inhibits NHE3 in a renal cell line. DA acutely decreases surface NHE3 antigen in dose- and time-dependent fashion without altering total cellular NHE3. Although DA(1) receptor agonist alone decreases surface NHE3, simultaneous DA(2) agonist synergistically enhances the effect of DA(1). Decreased surface NHE3 antigen, caused by stimulation of NHE3 endocytosis, is dependent on intact functioning of the GTPase dynamin and involves increased binding of NHE3 to the adaptor protein AP2. DA-stimulated NHE3 endocytosis can be blocked by pharmacologic or genetic protein kinase A inhibition or by mutation of two protein kinase A target serines (Ser-560 and Ser-613) on NHE3. We conclude that one mechanism by which DA induces natriuresis is via protein kinase A-mediated phosphorylation of proximal tubule NHE3 leading to endocytosis of NHE3 via clathrin-coated vesicles.

Involvement of hematopoietic progenitor kinase 1 in T cell receptor signaling

Hematopoietic progenitor kinase 1 (HPK1), a mammalian Ste20-related serine/threonine protein kinase, is a hematopoietic-specific upstream activator of the c-Jun N-terminal kinase. Here, we provide evidence to demonstrate the involvement of HPK1 in T cell receptor (TCR) signaling. HPK1 was activated and tyrosine-phosphorylated with similar kinetics following TCR/CD3 or pervanadate stimulation. Co-expression of protein-tyrosine kinases, Lck and Zap70, with HPK1 led to HPK1 activation and tyrosine phosphorylation in transfected mammalian cells. Upon TCR/CD3 stimulation, HPK1 formed inducible complexes with the adapters Nck and Crk with different kinetics, whereas it constitutively interacted with the adapters Grb2 and CrkL in Jurkat T cells. Interestingly, HPK1 also inducibly associated with linker for activation of T cells (LAT) through its proline-rich motif and translocated into glycolipid-enriched microdomains (also called lipid rafts) following TCR/CD3 stimulation, suggesting a critical role for LAT in the regulation of HPK1. Together, these results identify HPK1 as a new component of TCR signaling. T cell-specific signaling molecules Lck, Zap70, and LAT play roles in the regulation of HPK1 during TCR signaling. Differential complex formation between HPK1 and adapters highlights the possible involvement of HPK1 in multiple signaling pathways in T cells.

Spa contributes to the virulence of type 18 group A streptococci

Streptococcal protective antigen (Spa) is a newly described surface protein of group A streptococci that was recently shown to evoke protective antibodies (J. B. Dale, E. Y. Chiang, S. Liu, H. S. Courtney, and D. L. Hasty, J. Clin. Investig. 103:1261--1268, 1999). In this study, we have determined the complete sequence of the spa gene from type 18 streptococci. Purified, recombinant Spa protein evoked antibodies that were bactericidal against type 18 streptococci, confirming the presence of protective epitopes. Sera from patients with acute rheumatic fever contained antibodies against recombinant Spa, indicating that the Spa protein is expressed in vivo and is immunogenic in humans. To determine the role of Spa in the virulence of group A streptococci, we created a series of insertional mutants that were (i) Spa negative and M18 positive, (ii) Spa positive and M18 negative, and (iii) Spa negative and M18 negative. The mutants and the parent M18 strain (18-282) were used in assays to determine resistance to phagocytosis, growth in human blood, and mouse virulence. The results show that Spa is a virulence determinant of group A streptococci and that expression of both Spa and M18 is required for optimal virulence of type 18 streptococci.

Functions of the upstream and proximal steroidogenic factor 1 (SF-1)-binding sites in the CYP11A1 promoter in basal transcription and hormonal response

The CYP11A1 gene encodes P450scc (cholesterol side-chain cleavage enzyme), which catalyzes the first step for the synthesis of steroids. Expression of CYP11A1 is controlled by transcription factor SF-1 (steroidogenic factor 1). Two functional SF-1-binding sites, P and U, located at -40 and -1,600 regions of the CYP11A1 gene, have been identified, but their exact functions with respect to basal activation vs. cAMP response have not been dissected. We have addressed this question by examining the ability of the mutated human CYP11A1 promoter to drive LacZ reporter gene expression in transgenic mouse lines. The activity of the mtP mutant promoter was greatly reduced, indicating the importance of the P site. Mutation of the upstream U site also resulted in reduced reporter gene expression, but some residual activity remained. This residual reporter gene activity was detected in the adrenal and gonad in a tissue-specific manner. ACTH and hCG can stimulate LacZ gene expression in the adrenals and testes of transgenic mice driven by the wild-type but not the mtU promoter. These results indicate that the upstream SF-1-binding site is required for hormonal stimulation. Our experiments demonstrate the participation of both the proximal and the upstream SF-1-binding sites in hormone-responsive transcription.

Regulation of steroidogenesis in transgenic mice and zebrafish

Steroid hormones are important physiological regulators in the body. Steroid hormones are mainly synthesized in the adrenal and gonads. Their synthesis is stimulated by pituitary hormones through cAMP as an intracellular mediator. The first and rate-limiting step for steroid biosynthesis is catalyzed by CYP11A1. Important regulatory elements for the control of the CYP11A1 gene expression have been characterized both in vitro and in vivo. The SF-1-binding sites are cis-acting elements controlling the basal and cAMP-stimulated gene expression. Our transgenic mouse studies showed that the 2.3kb promoter contains information controlling developmentally regulated gene expression. Finally, we present our results on the cloning of steroidogenic genes in zebrafish, a new model organism for genetic studies.

HER-2/neu promotes androgen-independent survival and growth of prostate cancer cells through the Akt pathway

HER-2/neu has been implicated in the activation of androgen receptor (AR) and in inducing hormone-independent prostate cancer growth. Here we report that HER-2/neu activates Akt (protein kinase B) to promote prostate cancer cell survival and growth in the absence of androgen. Blocking of the Akt pathway by a dominant-negative Akt or an inhibitor LY294002 abrogates the HER-2/neu-induced AR signaling and cell survival/growth effects in the absence or presence of androgen. Akt specifically binds to AR and phosphorylates serines 213 and 791 of AR. Thus, Akt is a novel activator of AR required for HER-2/neu signaling to androgen-independent survival and growth of prostate cancer cells.

Acute regulation of Na+/H+ exchanger NHE3 by parathyroid hormone via NHE3 phosphorylation and dynamin-dependent endocytosis

Parathyroid hormone (PTH) is a potent inhibitor of mammalian renal proximal tubule Na(+) transport via its action on the apical membrane Na(+)/H(+) exchanger NHE3. In the opossum kidney cell line, inhibition of NHE3 activity was detected from 5 to 45 min after PTH addition. Increase in NHE3 phosphorylation on multiple serines was evident after 5 min of PTH, but decrease in surface NHE3 antigen was not detectable until after 30 min of PTH. The decrease in surface NHE3 antigen was due to increased NHE3 endocytosis. When endocytic trafficking was arrested with a dominant negative dynamin mutant (K44A), the early inhibition (5 min) of NHE3 activity by PTH was not affected, whereas the late inhibition (30 min) and decreased surface NHE3 antigen induced by PTH were abrogated. We conclude that PTH acutely inhibits NHE3 activity in a biphasic fashion by NHE3 phosphorylation followed by dynamin-dependent endocytosis.

Massive reduction of urea transporters in remnant kidney and brain of uremic rats

BACKGROUND

The facilitated urea transporters (UT), UT-A1, UT-A2, and UT-B1, are involved in intrarenal recycling of urea, an essential feature of the urinary concentrating mechanism, which is impaired in chronic renal failure (CRF). In this study, the expression of these UTs was examined in experimentally induced CRF.

METHODS

The abundance of mRNA was measured by Northern analysis and that of corresponding proteins by Western blotting in rats one and five weeks after 5/6 nephrectomy (Nx).

RESULTS

At five weeks, urine output was enhanced threefold with a concomitant decrease in urine osmolality. The marked rise in plasma urea concentration and fall in urinary urea concentration resulted in a 30-fold decrease in the urine/plasma (U/P) urea concentration ratio, while the U/P osmoles ratio fell only fourfold. A dramatic decrease in mRNA abundance for the three UTs was observed, bringing their level at five weeks to 1/10th or less of control values. Immunoblotting showed complete disappearance of the 97 and 117 kD bands of UT-A1, and considerable reduction of UT-A2 and UT-B1 in the renal medulla. Similar, but less intense, changes were observed at one-week post-Nx. In addition to the kidney, UT-B1 is also normally expressed in brain and testis. In the brain, its mRNA expression remained normal one-week post-Nx, but decreased to about 30% of normal at five-weeks post-Nx, whereas no change was seen in testis.

CONCLUSIONS

(1) The decline in urinary concentrating ability seen in CRF is largely due to a major reduction of UTs involved in the process of urea concentration in the urine, while factors enabling the concentration of other solutes are less intensely affected. (2) The marked reduction of brain UT expression in CRF may be responsible for brain edema of dialysis disequilibrium syndrome observed in some patients after fast dialysis.

High tumoral maspin expression is associated with improved survival of patients with oral squamous cell carcinoma

Maspin, a member of the serpin family of protease inhibitors, is known to have tumor-suppressor functions. However, the association between its expression level and survival has not been demonstrated in human cancer. Using the immunohistochemical technique to examine the expression levels of maspin in 44 cases of oral squamous cell carcinoma (SCC), we found that 66% of the cases expressed low to intermediate levels of maspin and 34% of the cases expressed high levels of maspin. We further examined maspin protein expression in a series of six SCC cell lines from the head and neck, and found that all but one expressed low or no maspin protein. We also compared the clinicopathological features of the oral SCC cases with the maspin expression level, and found that high maspin expression was associated with the absence of lymph node metastasis. More importantly, we showed that higher maspin expression was significantly associated with better rates of overall survival, suggesting that high maspin expression may be a favorable prognostic marker for oral SCC.

High tumoral maspin expression is associated with improved survival of patients with oral squamous cell carcinoma

Maspin, a member of the serpin family of protease inhibitors, is known to have tumor-suppressor functions. However, the association between its expression level and survival has not been demonstrated in human cancer. Using the immunohistochemical technique to examine the expression levels of maspin in 44 cases of oral squamous cell carcinoma (SCC), we found that 66% of the cases expressed low to intermediate levels of maspin and 34% of the cases expressed high levels of maspin. We further examined maspin protein expression in a series of six SCC cell lines from the head and neck, and found that all but one expressed low or no maspin protein. We also compared the clinicopathological features of the oral SCC cases with the maspin expression level, and found that high maspin expression was associated with the absence of lymph node metastasis. More importantly, we showed that higher maspin expression was significantly associated with better rates of overall survival, suggesting that high maspin expression may be a favorable prognostic marker for oral SCC.

HER-2/neu blocks tumor necrosis factor-induced apoptosis via the Akt/NF-kappaB pathway

Overexpression of HER-2/neu correlates with poor survival of breast and ovarian cancer patients and induces resistance to tumor necrosis factor (TNF), which causes cancer cells to escape from host immune defenses. The mechanism of HER-2/neu-induced TNF resistance is unknown. Here we report that HER-2/neu activates Akt and NF-kappaB without extracellular stimulation. Blocking of the Akt pathway by a dominant-negative Akt sensitizes the HER-2/neu-overexpressing cells to TNF-induced apoptosis and inhibits IkappaB kinases, IkappaB phosphorylation, and NF-kappaB activation. Our results suggested that HER-2/neu constitutively activates the Akt/NF-kappaB anti-apoptotic cascade to confer resistance to TNF on cancer cells and reduce host defenses against neoplasia.

A secreted and LIF-mediated stromal cell-derived activity that promotes ex vivo expansion of human hematopoietic stem cells

The development of culture systems that facilitate ex vivo maintenance and expansion of transplantable hematopoietic stem cells (HSCs) is vital to stem cell research. Establishment of such culture systems will have significant impact on ex vivo manipulation and expansion of transplantable stem cells in clinical applications such as gene therapy, tumor cell purging, and stem cell transplantation. We have recently developed a stromal-based culture system that facilitates ex vivo expansion of transplantable human HSCs. In this stromal-based culture system, 2 major contributors to the ex vivo stem cell expansion are the addition of leukemia inhibitory factor (LIF) and the AC6.21 stromal cells. Because the action of LIF is indirect and mediated by stromal cells, we hypothesized that LIF binds to the LIF receptor on AC6.21 stromal cells, leading to up-regulated production of stem cell expansion promoting factor (SCEPF) and/or down-regulated production of stem cell expansion inhibitory factor (SCEIF). Here we demonstrate a secreted SCEPF activity in the conditioned media of LIF-treated AC6.21 stromal cell cultures (SCM-LIF). The magnitude of ex vivo stem cell expansion depends on the concentration of the secreted SCEPF activity in the SCM-LIF. Furthermore, we have ruled out the contribution of 6 known early-acting cytokines, including interleukin-3, interleukin-6, granulocyte macrophage colony-stimulating factor, stem cell factor, flt3 ligand, and thrombopoietin, to this SCEPF activity. Although further studies are required to characterize this secreted SCEPF activity and to determine whether this secreted SCEPF activity is mediated by a single factor or by multiple growth factors, our results demonstrate that stromal cells are not required for this secreted SCEPF activity to facilitate ex vivo stem cell expansion. (Blood. 2000;95:1957-1966)

Tissue-specific, hormonal, and developmental regulation of SCC-LacZ expression in transgenic mice leads to adrenocortical zone characterization

We report here the study of the human CYP11A1 promoter in driving tissue-specific, developmentally and hormonally regulated reporter gene expression. A 4.4-kb fragment containing all known regulatory elements is more efficient than a short basal promoter fused to an upstream adrenal enhancer in driving reporter LacZ gene expression both in cell culture and in transgenic mice. The LacZ gene controlled by the 4.4- and 2.3-kb promoters was expressed in the adrenal cortex, testicular Leydig cells, ovarian corpora lutea, and granulosa cells. Transgene expression in the adrenals was stimulated by ACTH, indicating the presence of ACTH-responsive sequence. Beta-galactosidase activity was first detected in the adrenal primordia at 11.5 days postcoitum. Its expression continued throughout all stages of adrenal development in a pattern similar to that of the endogenous CYP11A1, which was expressed in all zones of the adrenal cortex, but was strongest in the X zone. The X zone grew before puberty but regressed afterward, as did the levels of CYP11A1 and LacZ gene expression in the X zone. Our study of the CYP11A1 promoter in transgenic mice led to characterization of the adrenocortical zones.

Hematopoietic progenitor kinase-1 (HPK1) stress response signaling pathway activates IkappaB kinases (IKK-alpha/beta) and IKK-beta is a developmentally regulated protein kinase

Nuclear factor kappa-B (NF-kappaB) is a pleiotropic transcription factor that plays a central role in the immune and inflammatory responses, and is also involved in controlling viral transcription and apoptosis. A critical control in the activation of NF-kappaB is the phosphorylation of its inhibitory factor IkappaBs by IkappaB kinases (IKK-alpha and -beta). Here, we present experiments addressing the regulation and global expression of murine IKK-beta, and localize the IKK-beta gene to mouse chromosome 8A3-A4. IKK-beta was expressed primarily in the liver, kidney and spleen, and at lower levels in the other adult tissues. While IKK-beta was expressed ubiquitously throughout the mouse embryo at 9.5 days, its expression began to be localized to the brain, neural ganglia, neural tube, and liver in the 12.5-day's embryo. At 15.5 days, the expression of IKK-beta was further restricted to specific tissues of the embryo, suggesting that IKK-beta is a developmentally regulated protein kinase. Interestingly, IKK-beta phosphorylated IkappaB constitutively, whereas IKK-alpha was not active in the absence of cell stimulation. Moreover, both IKK-alpha and -beta were activated by hematopoietic progenitor kinase-1 (HPK1) and MAPK/ERK kinase kinase-1 (MEKK1) specifically, suggesting that IkappaB/NF-kappaB is regulated through the HPK1-MEKK1 stress response signaling pathway.

Long-term ex vivo maintenance and expansion of transplantable human hematopoietic stem cells

We have developed a stromal-based in vitro culture system that facilitates ex vivo expansion of transplantable CD34(+) thy-1(+) cells using long-term hematopoietic reconstitution in severe combined immunodeficient-human (SCID-hu) mice as an in vivo assay for transplantable human hematopoietic stem cells (HSCs). The addition of leukemia inhibitory factor (LIF) to purified CD34(+) thy-1(+) cells on AC6.21 stroma, a murine bone marrow-derived stromal cell line, caused expansion of cells with CD34(+) thy-1(+) phenotype. Addition of other cytokines, including interleukin-3 (IL-3), IL-6, granulocyte-macrophage colony-stimulating factor, and stem cell factor, to LIF in the cultures caused a 150-fold expansion of cells retaining the CD34(+) thy-1(+) phenotype. The ex vivo-expanded CD34(+) thy-1(+) cells gave rise to multilineage differentiation, including myeloid, T, and B cells, when transplanted into SCID-hu mice. Both murine LIF (cannot bind to human LIF receptor) and human LIF caused expansion of human CD34(+) thy-1(+) cells in vitro, suggesting action through the murine stroma. Furthermore, another human HSC candidate, CD34(+) CD38(-) cells, shows a similar pattern of proliferative response. This suggests that ex vivo expansion of transplantable human stem cells under this in vitro culture system is a general phenomenon and not just specific for CD34(+) thy-1(+) cells.

E1A sensitizes cells to tumor necrosis factor-induced apoptosis through inhibition of IkappaB kinases and nuclear factor kappaB activities

The adenovirus E1A protein has been implicated in increasing cellular susceptibility to apoptosis induced by tumor necrosis factor (TNF); however, its mechanism of action is still unknown. Since activation of nuclear factor kappaB (NF-kappaB) has been shown to play an anti-apoptotic role in TNF-induced apoptosis, we examined apoptotic susceptibility and NF-kappaB activation induced by TNF in the E1A transfectants and their parental cells. Here, we reported that E1A inhibited activation of NF-kappaB and rendered cells more sensitive to TNF-induced apoptosis. We further showed that this inhibition was through suppression of IkappaB kinase (IKK) activity and IkappaB phosphorylation. Moreover, deletion of the p300 and Rb binding domains of E1A abolished its function in blocking IKK activity and IkappaB phosphorylation, suggesting that these domains are essential for the E1A function in down-regulating IKK activity and NF-kappaB signaling. However, the role of E1A in inhibiting IKK activity might be indirect. Nevertheless, our results suggest that inhibition of IKK activity by E1A is an important mechanism for the E1A-mediated sensitization of TNF-induced apoptosis.

Human fibroblast growth factor-18 stimulates fibroblast cell proliferation and is mapped to chromosome 14p11

The fibroblast growth factors (FGFs) play crucial roles in controlling embryonic development, cell growth, morphogenesis, and tissue repair in animals. Furthermore, FGFs may have a role in angiogenesis and may be involved in tumor invasion and metastasis. Here, we present the cloning and sequence of human FGF-18, a novel member of the FGF family. Sequence comparison indicates that FGF-18 is conserved with the other FGFs and most homologous to FGF-8 among the FGF family members. We showed that human FGF-18 was expressed primarily in the heart, skeletal muscle, and pancreas, and at lower levels in the other tissues. FGF-18 was also expressed at low levels in certain cancer cell lines. FGF-18 contains a typical signal peptide and was secreted when it was transfected into mammalian cells. Recombinant FGF-18 protein stimulated proliferation in the fibroblast cell line NIH3T3 in a dose-dependent manner, suggesting that FGF-18 is a functional growth factor. Finally, the FGF-18 gene was evolutionarily conserved, and localized to human chromosome 14p11.

Murine p38-delta mitogen-activated protein kinase, a developmentally regulated protein kinase that is activated by stress and proinflammatory cytokines

The p38 mitogen-activated protein kinases (MAPK) play a crucial role in stress and inflammatory responses and are also involved in activation of the human immunodeficiency virus gene expression. We have isolated the murine cDNA clones encoding p38-delta MAPK, and we have localized the p38-delta gene to mouse chromosome 17A3-B and human chromosome 6p21.3. By using Northern and in situ hybridization, we have examined the expression of p38-delta in the mouse adult tissues and embryos. p38-delta was expressed primarily in the lung, testis, kidney, and gut epithelium in the adult tissues. Although p38-delta was expressed predominantly in the developing gut and the septum transversum in the mouse embryo at 9.5 days, its expression began to be expanded to many specific tissues in the 12.5-day embryo. At 15.5 days, p38-delta was expressed virtually in most developing epithelia in embryos, suggesting that p38-delta is a developmentally regulated MAPK. Interestingly, p38-delta and p38-alpha were similar serine/threonine kinases but differed in substrate specificity. Overall, p38-delta resembles p38-gamma, whereas p38-beta resembles p38-alpha. Moreover, p38-delta is activated by environmental stress, extracellular stimulants, and MAPK kinase-3, -4, -6, and -7, suggesting that p38-delta is a unique stress-responsive protein kinase.

rRNA-complementarity in the 5' untranslated region of mRNA specifying the Gtx homeodomain protein: evidence that base- pairing to 18S rRNA affects translational efficiency

Numerous eukaryotic mRNAs contain sequences complementary to segments of the 18S and 28S rRNAs. Previous studies raised the possibility that these complementarities might allow mRNA-rRNA interactions and affect rates of translation. In the present study, we investigated the mRNA encoding the mouse Gtx homeodomain protein. This mRNA contains within its 5' untranslated region (UTR) a segment that is complementary to two regions of the 18S rRNA, located at nucleotides 701-741 and 1104-1136. A Gtx RNA probe containing this complementarity could be photochemically cross-linked to ribosomal subunits through a linkage to 18S rRNA but not to 28S rRNA. Oligonucleotide-directed RNase H digestion of the rRNA and a reverse transcription analysis localized the cross-linked probe to the complementary segment of 18S rRNA at nucleotides 1104-1136 but not at nucleotides 701-741. To determine whether complementarity in the Gtx mRNA affected translation, a mutational analysis was performed with a Gtx-luciferase fusion construct and four related constructs with altered complementarity to the 18S rRNA. These constructs were examined for their ability to be translated in cell-free lysates prepared from P19 embryonal carcinoma and C6 glioma cell lines and after cellular transfection into these same cell lines. In both cell-free translation and transfection studies, the rate of translation decreased more than 9-fold as the degree of complementarity to nucleotides 1104-1136 of the 18S rRNA increased. We hypothesize that segments complementary to rRNA, such as those contained within the Gtx mRNA, form a category of cis-acting regulatory elements in mRNAs that affect translation by base pairing to rRNA within ribosomes.

mRNA expression of renal urea transporters in normal and Brattleboro rats: effect of dietary protein intake

Differences in dietary protein level induce differences in fractional excretion of urea, in arginine vasopressin (AVP) plasma level, and in urine concentrating activity (in which intervene the renal urea transporters (UT)). The abundance of mRNA for UT-A1 (of the inner medullary collecting duct, IMCD) UT-A2 (of the descending thin limb) and UT-B1 (of descending vasa recta) was determined by Northern analysis of total RNA extracted from medullary subregions of Sprague-Dawley rats fed for 1 week, a low, normal, or high protein diet. The implication of AVP was then examined by studying AVP-deprived (Brattleboro) rats. Our results show that none of these transporters is affected by the level of protein intake, except UT-A1 that is reduced in terminal IMCD by low protein diet in the absence of AVP (Brattleboro rats). These data suggest that (1) the previously reported effect of kidney medulla hypertonicity on UT-A2 and UT-B1 mRNA expression is somehow obliterated by protein intake deficiency or excess, and (2) AVP influences the mRNA abundance of the UT-A1 of the terminal IMCD during protein deficiency.

Protein phosphatase X interacts with c-Rel and stimulates c-Rel/nuclear factor kappaB activity

Nuclear factor kappaB (NF-kappaB) and the Rel family of proteins are pleiotropic transcription factors that play central roles in the immune and inflammatory responses, as well as apoptosis. Here, we identified a serine/threonine protein phosphatase X (PPX; also called protein phosphatase 4 (PP4)) that specifically associated with c-Rel, NF-kappaB p50, and RelA. The amino acid sequences of human and mouse PPX are 100% identical, and the PPX gene was mapped to human chromosome 16 p11.2. Overexpression of PPX, but not catalytically inactive PPX mutants, stimulated the DNA-binding activity of c-Rel and activated NF-kappaB-mediated transcription. These results suggest that PPX is a novel activator of c-Rel/NF-kappaB.

IkappaB kinase-alpha and -beta genes are coexpressed in adult and embryonic tissues but localized to different human chromosomes

Activation of the transcription factor nuclear factor kappa B (NF-kappaB) is regulated by phosphorylation, ubiquitination, and degradation of its inhibitory factor IkappaB. Very recently, two closely related serine/threonine kinases have been identified as IkappaB kinases which are essential for IkappaB phosphorylation and NF-kappaB activation. Here, we isolated the full-length human cDNA clones encoding these two IkappaB kinases, IKK-alpha and IKK-beta. Both polypeptides contain a conserved amino-terminal kinase domain, a leucine zipper motif and a helix-loop-helix domain at their carboxyl terminus. We showed that IKK-alpha and IKK-beta were coexpressed in most human adult tissues as well as in different developmental stages of mouse embryos, suggesting that they may cooperate in the cells. The IKK-alpha and IKK-beta genes are distinct but evolutionarily conserved. Moreover, the IKK-alpha gene locus was mapped to human chromosome 10q24, whereas the IKK-beta gene locus was localized to human chromosome 8p11.2. These results indicated that both genes are not clustered on the same chromosome; nevertheless, both genes may be still regulated similarly during development and in adult tissues.

rRNA complementarity within mRNAs: a possible basis for mRNA-ribosome interactions and translational control

Our recent demonstration that many eukaryotic mRNAs contain sequences complementary to rRNA led to the hypothesis that these sequences might mediate specific interactions between mRNAs and ribosomes and thereby affect translation. In the present experiments, the ability of complementary sequences to bind to rRNA was investigated by using photochemical cross-linking. RNA probes with perfect complementarity to 18S or 28S rRNA were shown to cross-link specifically to the corresponding rRNA within intact ribosomal subunits. Similar results were obtained by using probes based on natural mRNA sequences with varying degrees of complementarity to the 18S rRNA. RNase H cleavage localized four such probes to complementary regions of the 18S rRNA. The effects of complementarity on translation were assessed by using the mRNA encoding ribosomal protein S15. This mRNA contains a sequence within its coding region that is complementary to the 18S rRNA at 20 of 22 nucleotides. RNA from an S15-luciferase fusion construct was translated in a cell-free lysate and compared with the translation of four related constructs that were mutated to decrease complementarity to the 18S rRNA. These mutations did not alter the amino acid sequence or the codon bias. A correlation between complementarity and translation was observed; constructs with less complementarity increased the amount of translation up to 54%. These findings raised the possibility that direct base-pairing of particular mRNAs to rRNAs within ribosomes may function as a mechanism of translational control.

FGF-18, a novel member of the fibroblast growth factor family, stimulates hepatic and intestinal proliferation

The fibroblast growth factors (FGFs) play key roles in controlling tissue growth, morphogenesis, and repair in animals. We have cloned a novel member of the FGF family, designated FGF-18, that is expressed primarily in the lungs and kidneys and at lower levels in the heart, testes, spleen, skeletal muscle, and brain. Sequence comparison indicates that FGF-18 is highly conserved between humans and mice and is most homologous to FGF-8 among the FGF family members. FGF-18 has a typical signal sequence and was glycosylated and secreted when it was transfected into 293-EBNA cells. Recombinant murine FGF-18 protein (rMuFGF-18) stimulated proliferation in the fibroblast cell line NIH 3T3 in vitro in a heparan sulfate-dependent manner. To examine its biological activity in vivo, rMuFGF-18 was injected into normal mice and ectopically overexpressed in transgenic mice by using a liver-specific promoter. Injection of rMuFGF-18 induced proliferation in a wide variety of tissues, including tissues of both epithelial and mesenchymal origin. The two tissues which appeared to be the primary targets of FGF-18 were the liver and small intestine, both of which exhibited histologic evidence of proliferation and showed significant gains in organ weight following 7 (sometimes 3) days of FGF-18 treatment. Transgenic mice that overexpressed FGF-18 in the liver also exhibited an increase in liver weight and hepatocellular proliferation. These results suggest that FGF-18 is a pleiotropic growth factor that stimulates proliferation in a number of tissues, most notably the liver and small intestine.

Renal tubular and vascular urea transporters: influence of antidiuretic hormone on messenger RNA expression in Brattleboro rats

In the kidney, facilitated urea transport in precise vascular and tubular structures is mainly involved in water conservation. Three urea transporters have been cloned: UT2-long expressed in terminal inner medullary collecting duct (IMCD), UT2-short expressed in thin descending limb, and UT11 in descending vasa recta. The effect of arginine vasopressin (AVP) administration on mRNA expression of these three transporters was examined in Brattleboro rats with diabetes insipidus. V2 effects were discriminated from combined V1 + V2 effects by comparing treatments with 1-deamino-8-D-AVP (dDAVP) (selective V2 agonism) and AVP (V1 and V2 agonism). Acute and chronic treatments were studied. Abundance of specific mRNA was assessed by quantitative Northern blot analysis of RNA extracted from two regions of inner stripe of outer medulla and from two regions of inner medulla (IM). The results show that mRNA of these urea transporters are differently regulated by AVP. (1) Long-term treatment with either AVP or dDAVP does not alter UT2-long mRNA in tip IM (terminal IMCD) except for a transient initial decrease. (2) Unlike AVP, dDAVP induces the appearance of significant expression of UT2-long mRNA in base IM (initial IMCD), indicating a major V2 effect. (3) UT2-short mRNA in deep inner stripe of outer medulla and base IM (thin descending limb of short and long loops, respectively) is progressively upregulated with duration of AVP or dDAVP treatment. (4) The much higher changes in UT2-long and UT2-short induced by dDAVP compared with AVP suggest that they are dependent mainly on V2 agonism, and likely attenuated by V1 agonism. (5) UT11 mRNA expression in tip IM is equally depressed by AVP and dDAVP, indicating that this vascular transporter is also influenced by AVP and/or urine-concentrating activity, via an indirect mechanism that remains to be determined.

Genotoxicity of propoxur and its N-nitroso derivative in mammalian cells

N-Nitroso propoxur (NP) can be synthesized from a widely used N-methylcarbamate insecticide, propoxur, in vitro in the laboratory. Because of the extensive use of aerosol propoxur, the adverse effect on cells of respiratory origin is worth elucidating. In this report, two mammalian cell cultures from respiratory tissues [a hamster lung fibroblast, V79, and a primary rat tracheal epithelial cell (RTE)], were used to investigate the genotoxicity of propoxur and NP. NP was more cytotoxic than propoxur, with LC50s (20 and six times smaller, respectively in V79 and RTE cells. NP significantly induced sister chromatid exchange (> or = 0.01 microg/ml), chromosome aberration (> or = 2.5 microg/ml) and hprt gene mutation (> or = 0.5 microg/ml) in V79 cells, and cell transformation (> or = 0.2 microg/ml) in RTE cells. Results of chromosome aberration and hprt gene mutation indicated that the major pre-mutagenic lesion induced by NP must be the O6-methylguanine adduct, which frequently mispairs with thymine and thus gives rise to a GC-->AT transition. Propoxur was not mutagenic to either type of cells. However, it inhibited gap-junctional intercellular communication in V79 cells, which indicates that propoxur could act through some epigenetic mechanisms, such as tumor promotion or cell proliferation, in the multiple process of chemical carcinogenesis.

The cytoplasmic domain of stem cell antigen CD34 is essential for cytoadhesion signaling but not sufficient for proliferation signaling

CD34 is widely used as a marker in the identification and purification of human hematopoietic stem and progenitor cells; however, its function within hematopoiesis is largely unknown. We have investigated the contribution of cytoplasmic domain of CD34 in cytoadhesion signaling and proliferation signaling in hematopoietic cells. Engagement of particular determinants of CD34 by monoclonal antibodies leads to homotypic adhesiveness of the full-length CD34-transfected BaF3 cells. However, this homotypic adhesiveness is abrogated in BaF3 cells transfected with the truncated CD34 lacking the cytoplasmic domain. Cytoadhesion signaling through the cytoplasmic domain of CD34 cannot be restored through that of erythropoietin receptor (EPOR) or granulocyte colony-stimulating factor receptor (G-CSFR), suggesting that the cytoplasmic domain of CD34 is required for its signal transduction of cellular adhesion. In constrast, we show that replacing the cytoplasmic domain of EPOR or G-CSFR with that of CD34 abolished growth signal transduction in response to EPO or G-CSF in the chimeric receptor-transfected BaF3, 32D, and FDCP1 cells, whereas the wild-type EPOR- or G-CSFR-transfected cells responded to EPO or G-CSF growth signaling well. These results suggest that the cytoplasmic portion of CD34 may not contain the elements necessary to transduce a proliferative signal in hematopoietic cells. Thus, the function of CD34 in hematopoiesis is primarily on hematopoietic cell adhesion.

JNK1, JNK2 and JNK3 are p53 N-terminal serine 34 kinases

The function of the tumor suppressor protein p53 is modulated by post-translational events, primarily by phosphorylation. p53 is phosphorylated at multiple sites by a variety of protein kinases depending on the cellular environment. It has been suggested that serine 34 of mouse p53 is specifically phosphorylated by a stress-activated protein kinase in response to ultraviolet radiation. Since serine 34 is a major site of phosphorylation of mouse p53 in vivo and its specific protein kinase is still not definitively identified yet, we have examined the c-Jun N-terminal kinase 1 (JNK1) activity on p53 by expressing JNK1 in 293T cells. We show here that activated JNK1 phosphorylates mouse p53 specifically at serine 34 in vitro, while a dominanant-negative JNK1 mutant does not phosphorylate p53. More importantly, JNK1 associates with p53 in vivo, with or without activation, confirming that JNK1 is indeed a p53 kinase. Interestingly, activated JNK2 and JNK3 also phosphorylate serine 34 of mouse p53. Furthermore, JNK2 and JNK3 also associate with p53 in vivo, indicating that not only JNK1, but also JNK2 and JNK3 are p53 N-terminal serine 34 kinases. Phosphorylation of p53 by JNKs may play an important role in nuclear signal transduction in response to environmental stress or tumorigenic agents.

Normal human immunoglobulins for intravenous use (IVIg) delay hyperacute xenograft rejection through F(ab')2-mediated anti-complement activity

Xenotransplantation between discordant species leads to a hyperacute rejection mediated by natural antibodies, both of the IgG and IgM isotypes, activation of complement and endothelial cell activation. The combination of these mechanisms leads to a transplant survival of minutes to a few hours. Polyclonal human immunoglobulins for intravenous use (IVIg) from normal donors have proved effective in a number of antibody-mediated disorders, as well as in inflammatory disorders. We demonstrate that administration of IVIg in a guinea pig to rat model of cardiac xenografting can effectively delay hyperacute rejection. This effect is mediated by the F(ab')2 fragments of IVIg, and is correlated to an anti-complementary activity.

Activation of the hematopoietic progenitor kinase-1 (HPK1)-dependent, stress-activated c-Jun N-terminal kinase (JNK) pathway by transforming growth factor beta (TGF-beta)-activated kinase (TAK1), a kinase mediator of TGF beta signal transduction

Transforming growth factor beta (TGF-beta)-activated kinase (TAK1) is known for its involvement in TGF-beta signaling and its ability to activate the p38-mitogen-activated protein kinase (MAPK) pathway. This report shows that TAK1 is also a strong activator of c-Jun N-terminal kinase (JNK). Both the wild-type and a constitutively active mutant of TAK1 stimulated JNK in transient transfection assays. Mitogen-activated protein kinase kinase 4 (MKK4)/stress-activated protein kinase/extracellular signal-regulated kinase (SEK1), a dual-specificity kinase that phosphorylates and activates JNK, synergized with TAK1 in activating JNK. Conversely, a dominant-negative (MKK4/SEK1 mutant inhibited TAK1-induced JNK activation. A kinasedefective mutant of TAK1 effectively suppressed hematopoietic progenitor kinase-1 (HPK1)-induced JNK activity but had little effect on germinal center kinase activation of JNK. There are two additional MAPK kinase kinases, MEKK1 and mixed lineage kinase 3 (MLK3), that are also downstream of HPK1 and upstream of MKK4/SEK mutant. However, because the dominant-negative mutants of MEKK1 and MLK3 did not inhibit TAK1-induced JNK activity, we conclude that activation of JNK1 by TAK1 is independent of MEKK1 and MLK3. In addition to TAK1, TGF-beta also stimulated JNK activity. Taken together, these results identify TAK1 as a regulator in the HPK1 --> TAK1 --> MKK4/SEK1 --> JNK kinase cascade and indicate the involvement of JNK in the TGF-beta signaling pathway. Our results also suggest the potential roles of TAK1 not only in the TGF-beta pathway but also in the other HPK1/JNK1-mediated pathways.

Adenovirus E1B 19K protein is required for efficient DNA replication in U937 cells

The adenovirus E1B 19K gene plays an essential role in transformation of primary rodent cells in cooperation with E1A and in the inhibition of apoptosis during lytic infection. It has been shown that this E1B 19K protein is not necessary for viral DNA replication in human cell lines, such as HeLa and KB. We reported here that the E1B 19K mutant viruses were unable to replicate efficiently in a monocyte cell line, U937. Viral DNA synthesis and late gene expression were found to be defective in U937 cells infected with E1B 19K mutants compared with wild-type virus. Early viral RNA splicing patterns also differ between wild-type and dl337-infected cells. Furthermore, the defect in viral replication could be complemented by dl312 virus defective in E1A expression 4 days after infection with E1B mutants, suggesting persistence of the E1B mutant genome in the infected cells despite defective onset of the late phase of replication. These results imply that E1B 19K is required for efficient viral DNA replication in U937 cells. Inefficient DNA replication is also found in another monocyte cell line, THP-1.

Human HPK1, a novel human hematopoietic progenitor kinase that activates the JNK/SAPK kinase cascade

The c-Jun amino-terminal kinases (JNKs)/stress-activated protein kinases (SAPKs) play a crucial role in stress responses in mammalian cells. The mechanism underlying this pathway in the hematopoietic system is unclear, but it is a key in understanding the molecular basis of blood cell differentiation. We have cloned a novel protein kinase, termed hematopoietic progenitor kinase 1 (HPK1), that is expressed predominantly in hematopoietic cells, including early progenitor cells. HPK1 is related distantly to the p21(Cdc42/Rac1)-activated kinase (PAK) and yeast STE20 implicated in the mitogen-activated protein kinase (MAPK) cascade. Expression of HPK1 activates JNK1 specifically, and it elevates strongly AP-1-mediated transcriptional activity in vivo. HPK1 binds and phosphorylates MEKK1 directly, whereas JNK1 activation by HPK1 is inhibited by a dominant-negative MEKK1 or MKK4/SEK mutant. Interestingly, unlike PAK65, HPK1 does not contain the small GTPase Rac1/Cdc42-binding domain and does not bind to either Rac1 or Cdc42, suggesting that HPK1. activation is Rac1/Cdc42-independent. These results indicate that HPK1 is a novel functional activator of the JNK/SAPK signaling pathway.

Stimulation of macrophages and neutrophils by complexes of lipopolysaccharide and soluble CD14

Sensitive responses of monocytes, macrophages, and neutrophils to bacterial LPS require membrane-bound CD14 (mCD14) and a plasma protein called LPS-binding protein (LBP). Cells lacking mCD14 respond to complexes of LPS and soluble CD14 (sCD14); these responses do not require LBP. To determine whether LBP is necessary for responses of mCD14-bearing cells to LPS, we measured responses of macrophages and neutrophils to complexes of LPS and sCD14 formed in the absence of LBP. We found that the amount of LPS needed to induce adhesive responses of neutrophils or cytokine production by macrophages was the same whether LPS was added with LBP or as LPS-sCD14 complexes, and was &gt;100-fold less than when LPS was added alone. This result supports the view that LBP transfers LPS to CD14, but is not directly involved in responses of CD14-bearing cells to LPS. Responses of neutrophils to LPS-sCD14 complexes could be inhibited partially by blocking mCD14, suggesting that LPS may move rapidly from sCD14 to mCD14. Additionally, we found that responses of neutrophils to LBP and smooth LPS were made 30 to 100 times more sensitive when sCD14 was added. Our findings show that LBP is not necessary for the activation of CD14-bearing cells with LPS, and suggest that LPS-sCD14 complexes are an important intermediate in the inflammatory responses of leukocytes to LPS.

Stimulation of macrophages and neutrophils by complexes of lipopolysaccharide and soluble CD14

Sensitive responses of monocytes, macrophages, and neutrophils to bacterial LPS require membrane-bound CD14 (mCD14) and a plasma protein called LPS-binding protein (LBP). Cells lacking mCD14 respond to complexes of LPS and soluble CD14 (sCD14); these responses do not require LBP. To determine whether LBP is necessary for responses of mCD14-bearing cells to LPS, we measured responses of macrophages and neutrophils to complexes of LPS and sCD14 formed in the absence of LBP. We found that the amount of LPS needed to induce adhesive responses of neutrophils or cytokine production by macrophages was the same whether LPS was added with LBP or as LPS-sCD14 complexes, and was >100-fold less than when LPS was added alone. This result supports the view that LBP transfers LPS to CD14, but is not directly involved in responses of CD14-bearing cells to LPS. Responses of neutrophils to LPS-sCD14 complexes could be inhibited partially by blocking mCD14, suggesting that LPS may move rapidly from sCD14 to mCD14. Additionally, we found that responses of neutrophils to LBP and smooth LPS were made 30 to 100 times more sensitive when sCD14 was added. Our findings show that LBP is not necessary for the activation of CD14-bearing cells with LPS, and suggest that LPS-sCD14 complexes are an important intermediate in the inflammatory responses of leukocytes to LPS.

Function and membrane topology of wild-type and mutated cytochrome P-450c21

We have studied membrane topology of cytochrome P-450c21 (P450c21) using the approaches of mutagenesis and protease digestion. P450c21 is located at the cytoplasm with an N-terminal hydrophobic domain integrated into microsomal membranes. When this hydrophobic domain was replaced by a secretory signal peptide, P450c21 was translocated into the lumen and lost enzymic activity. No other topogenic sequence was detected in the bulk of the P450c21 peptide. A mutant protein with Pro-30 replaced by Leu (L30) corresponding to the mutation found in the diseased state was created. L30 protein lost 90% of enzymic activity, while a double mutant (L30R32) with an additional Leu-32 to Arg mutation had slightly higher residual enzymic activity. Apart from lower activity, L30 was also present in the cell at a lower level than wild-type P450c21. This lower level is probably due to increased degradation, as L30 is synthesized at a normal rate. Both L30 and L30R32 proteins, however, were integrated into membranes normally. Therefore the Pro-30 --> Leu mutation did not affect membrane integration, but affected the abundance and enzymic activity of P450c21.

Structure and expression of the CYP21 (P450c21, steroid 21-hydroxylase) gene with respect to its deficiency

Steroid 21-hydroxylase (P450c21) deficiency is the major cause of a common genetic disease, congenital adrenal hyperplasia, with the symptoms of virilization due to steroid imbalance. We have devised a fast diagnostic method to detect common mutations in the c21B gene by a two-step gene amplification procedure coupled to restriction digestion. This procedure does not require isotopes and is suitable for routine use in a hospital setting. In addition, we have developed a procedure for the production of active P450c21 in E. coli. We tested many different vector and bacterial strain combinations to find out the best condition for P450c21 expression. The bacteria harboring the P450c21 expression plasmid were grown in a rich media supplemented with trace metals, heme biosynthesis precursor delta-levulinic acid, and induced with IPTG at 20 degrees C for 48 h. We found that low growth temperature and long induction time were important for abundant synthesis of P450c21 in E. coli.

Na(+)-K(+)-ATPase activity: role in the impaired sodium excretion of experimental nephrosis in rats

Using the model of adriamycin-induced nephrotic syndrome in rats, we studied the relationship between urine electrolyte excretion rates and proteinuria and determined the activity of Na(+)-K(+)-ATPase in the renal tissue of nephrotic rats. No relationship was found between the increased sodium reabsorption and proteinuria. But the impaired salt excretion was inversely related to the increase of Na(+)-K(+)-ATPase activity in the renal inner medulla. It is proposed that direct effect of adriamycin on renal tubule cells is the primary events, that the increased Na(+)-ATPase activity on basolateral membrane of renal tubule cells be an intrarenal factor which mediates the action of retention of salt by the kidney and that inner medullary collecting ducts might be one of the sites of the sodium retention in nephrotic rats.

The N-terminal hydrophobic domain of P450c21 is required for membrane insertion and enzyme stability

Microsomal cytochromes P-450 are known to be integrated into smooth endoplasmic reticulum through their hydrophobic sequences located at the N termini. The length requirement of the membrane insertion signal was determined by the generation of six plasmids encoding mutant P450c21 that lacked various portions of the N-terminal hydrophobic domains. When they were transcribed and translated in vitro in the presence of endoplasmic reticulum membranes, mutant protein lacking more than a third of the first hydrophobic domain gradually lost the ability to insert into the membrane and stayed mostly in the soluble fraction when the first N-terminal hydrophobic domain was removed. The steady-state amount of the truncated proteins was progressively reduced in parallel to the extent of their N-terminal deletions, due to their fast degradation. This process was accompanied by a decrease in the enzymatic activity. Therefore, the first hydrophobic domain of P450c21 not only serves as a membrane targeting and anchoring domain, but it is also important for the in vivo protein stability.

Mutagenicity and mutational spectrum of N-methyl-N'-nitro-N-nitrosoguanidine in the hprt gene in G1-S and late S phase of diploid human fibroblasts

To investigate the effect of DNA replication on the mutation spectrum induced in diploid human fibroblasts by N-methyl-N'-nitro-N-nitrosoguanidine (MNNG), cells were synchronized and exposed to MNNG either at the G1-S border or in late S phase, and the mutations in the hypoxanthine (guanine) phosphoribosyltransferase (hprt) gene were examined. The coding regions of 92 independent mutants were characterized by direct sequencing of mRNA-polymerase chain reaction-amplified complementary DNA. While there was little difference in the sensitivity of the two populations to the cytotoxic effects of MNNG, the frequency of mutants induced in late S populations was significantly lower than that induced in G1-S populations. The majority of induced complementary DNA mutations were single base substitutions (54%) and splice site mutations (43%). Analysis of the intron-exon boundaries of more than one-half of the splicing mutants showed that almost all contained base substitutions in the hprt gene. A broad mutational spectrum was observed in low-dose (4, 6, or 8 microM) treatments; only 27% were G to A transitions, whereas 80% of base substitutions derived from the high-dose (10 or 12 microM) treatments were G to A transitions in G1-S populations. An intermediate frequency (64%) of G to A transitions was observed in late S populations exposed to MNNG. When the causative premutation lesion was O6-methylguanine, 75% of G to A transitions that were observed in G1-S populations clustered on both the transcribed and the nontranscribed strands of the 5' half of the hprt gene. In contrast, 50% of G to A transitions were located only on the nontranscribed strand of this region in late S populations. The results indicate that O(6)-alkylguanine-DNA-alkyltransferase may not efficiently remove O(6)-methylguanine from the 5' half of the gene but can repair lesions far away from this region during initiation of replication. Our results are consistent with the notion that the putative origin of replication is located at intron 1 of the hprt gene.