Effects of dynorphin A (1-17) on motor function and spinal intracellular messenger systems in rat

The effect of intrathecal injection of dynorphin A (1-17) on second messenger systems of spinal cord relative to behavioral change in rats was studied. Dynorphin A (1-17) 5, 10 (20 nmol) caused dose-dependent flaccid paralysis of hindlimbs. Dynorphin A (1-17) 10, 20 nmol dose-dependently decreased spinal adenylate cyclase (AC) activity, cyclic AMP production, calmodulin (CaM) level and cyclic-nucleotide phosphodiesterase (PDE) activity 10 min after intrathecal injection. They recovered to a varying extent two hours later. Pretreatment with selective kappa-opioid receptor antagonist nor-BNI 30 nmol 10 min before dynorphin A (1-17) markedly antagonized the effects of dynorphin A (1-17) at 20 nmol on hindlimb paralysis and inhibition of intracellular second messengers. The L-type calcium channel blocker verapamil (100 nmol) also played a role in blocking dynorphin neurotoxicity. The NMDA receptor antagonist APV could partially or completely block dynorphin inhibition of CaM level and PDE activity without affecting paralysis and decrease of AC-cAMP level induced by dynorphin A (1-17) 10 min after intrathecal injection.

In its active form, the GTP-binding protein rab8 interacts with a stress-activated protein kinase

Rab8 is a small GTP-binding protein that plays a role in vesicular transport from the trans-Golgi network to the basolateral plasma membrane in polarized epithelial cells (MDCK), and to the dendritic surface in hippocampal neurons. As is the case for most other rab proteins, the precise molecular interactions by which rab8 carries out its function remain to be elucidated. Here we report the identification and the complete cDNA-derived amino acid sequence of a murine rab8-interacting protein (rab8ip) that specifically interacts with rab8 in a GTP-dependent manner. Rab8ip displays 93% identity with the GC kinase, a serine/threonine protein kinase recently identified in human lymphoid tissue that is activated in the stress response. Like the GC kinase, rab8ip has protein kinase activity manifested by autophosphorylation and phosphorylation of the classical serine/threonine protein kinase substrates, myelin basic protein and casein. When coexpressed in transfected 293T cells, rab8 and the rab8ip/GC kinase formed a complex that could be recovered by immunoprecipitation with antibodies to rab8. Cell fractionation and immunofluorescence analyses indicate that in MDCK cells endogenous rab8ip is present both in the cytosol and as a peripheral membrane protein concentrated in the Golgi region and basolateral plasma membrane domains, sites where rab8 itself is also located. In light of recent evidence that rab proteins may act by promoting the stabilization of SNARE complexes, the specific GTP-dependent association of rab8 with the rab8ip/GC kinase raises the possibility that rab-regulated protein phosphorylation is important for vesicle targeting or fusion. Moreover, the rab8ip/GC kinase may serve to modulate secretion in response to stress stimuli.

Liposome-mediated transfer of genes containing HLA-class II alpha chain into cultured embryonic chick cardiac myocytes and COS7 cells

Rejection remains a major problem after cardiac transplantation. One hypothesis is that transfer of recipient HLA genes could lead to expression of the antigens on the surface of donor cells and so facilitate graft acceptance. This paper describes a pilot study for relevant gene-transfer (transfection) experiments on adult cardiac myocytes, investigating the feasibility of transfection using cationic liposomes. The plasmid pcDV1-pL2 vector containing HLA-DR-alpha chain gene was incubated with Lipofectin, a DOTMA and DOPE lipid mixture, for 10 minutes. Embryonic chick cardiac myocytes (ECCM) and COS7 monkey cells were incubated with DNA: Lipofectin ratios of 1:1, 1:2, 1:4, and 1:10 for 16 hours (hrs). Using a fixed ratio of 1:4, incubation periods of 4, 8, and 16 hrs were compared. Finally, cells were incubated for 16 hrs and consecutively cultured for 6 days. Expression of the HLA-DR-alpha chain antigen was detected by indirect immunohistochemical staining. Highest transfection rates were achieved with a DNA: Lipofectin ratio of 1:4 for ECCM and COS7 cells (2.7% +/- 0.6% and 2.4% +/- 0.3% after 16 hrs incubation) and a transfection time of 4 hrs (5.8% +/- 0.6% and 5.3% +/- 1.7%). Immunohistochemically positive cells were present after 6 days (2.0% +/- 1.2% and 2.1% +/- 0.3%). We found a low level of expression of HLA-DR-alpha chain gene, influenced by transfection time and DNA: Lipofectin ratio. To increase the efficiency of liposome-mediated gene transfer and assess potential applications in cardiac transplantation, further investigation of cell properties promoting transfection is necessary.

Immunohistochemical localization of steroid 5 alpha-reductase 2 in the human male fetal reproductive tract and adult prostate

The activity of the type 2 isozyme of steroid 5 alpha-reductase is crucial for normal development of the external genitalia and prostate in human males. We used immunohistochemistry to localize type 2 isozyme expression in the human male fetal reproductive tract and adult prostate. In fetal tissue, the stroma of the seminal vesicles, corpus cavernosum, corpus spongiosum, dorsal vein complex, scrotal skin, and prostate expressed the enzyme. In addition, the epithelial cells of the fetal urethra and proximal prostatic ducts stained positively. The type 2 isozyme could not be detected in epithelial cells of the fetal prostatic acini, seminal vesicles, prostatic utricle, ejaculatory ducts, epididymides, and Cowper's glands. Adult prostate specimens were derived from transurethral prostatectomies performed for benign prostatic hyperplasia. Enzyme expression in these benign prostatic hyperplasia samples localized to the stroma and epithelial cells of the urethra and proximal ducts. No staining was detected in the acinar (luminal and basal) epithelial cells. Double staining with an antismooth muscle actin antibody localized type 2 isozyme expression to the stromal fibroblast cells of the prostate. Double staining with an androgen receptor antibody localized AR expression to the acinar epithelial cells and stromal fibroblasts. These data indicate that 5 alpha-reductase type 2 is expressed throughout the developing male genitourinary tract and functions as both an autocrine and a paracrine mediator of growth and differentiation.

Transformation of China's rural health care financing

In the late 1970s China launched its agricultural reforms which initiated a decade of continued economic growth and significant transformation of the Chinese society. The agricultural reforms altered the peasants' incentives, weakened community organization and lessened the central government's control over local communities. These changes largely caused the collapse of the widely acclaimed rural cooperative medical system in China. Consequently China experienced a decreased supply of rural health workers, increased burden of illnesses, disintegration of the three tier medical system, reduced primary health care, and an increased demand for hospital medical services. More than ten years have elapsed since China changed its agricultural economic system and China is still struggling to find an equitable, efficient and sustainable way of financing and organizing its rural health services. The Chinese experiences provided several important lessons for other nations: there is a need to understand the limits of the market forces and to redefine the role of the government in rural health care under a market economy; community participation in and control of local health financing schemes is essential in developing a sustainable rural health system; the rural health system needs to be dynamic, rather than static, to keep pace with changing demand and needs of the population.

Investigation of high-resolution angle sensing with laser mode-split technology

We present a new method of angular measurement, which is to rotate a 15-mm-diameter, 3-mm-thick crystal quartz plate in a He-Ne laser cavity to produce a laser mode split. The magnitude of the mode split (in hertz) represents the angle of rotation. The experimental devices used are described. The stability of the beat frequency is 0.78 kHz (1σ). A sensitivity of 2.62 3 × 10(4) Hz/", where" is angular seconds, has been reached and the repeatability is 0.3". The principal error factors are discussed.

Separate domains of the Ran GTPase interact with different factors to regulate nuclear protein import and RNA processing

The small Ras-related GTP binding and hydrolyzing protein Ran has been implicated in a variety of processes, including cell cycle progression, DNA synthesis, RNA processing, and nuclear-cytosolic trafficking of both RNA and proteins. Like other small GTPases, Ran appears to function as a switch: Ran-GTP and Ran-GDP levels are regulated both by guanine nucleotide exchange factors and GTPase activating proteins, and Ran-GTP and Ran-GDP interact differentially with one or more effectors. One such putative effector, Ran-binding protein 1 (RanBP1), interacts selectively with Ran-GTP. Ran proteins contain a diagnostic short, acidic, carboxyl-terminal domain, DEDDDL, which, at least in the case of human Ran, is required for its role in cell cycle regulation. We show here that this domain is required for the interaction between Ran and RanBP1 but not for the interaction between Ran and a Ran guanine nucleotide exchange factor or between Ran and a Ran GTPase activating protein. In addition, Ran lacking this carboxyl-terminal domain functions normally in an in vitro nuclear protein import assay. We also show that RanBP1 interacts with the mammalian homolog of yeast protein RNA1, a protein involved in RNA transport and processing. These results are consistent with the hypothesis that Ran functions directly in at least two pathways, one, dependent on RanBP1, that affects cell cycle progression and RNA export, and another, independent of RanBP1, that affects nuclear protein import.

Estrogen receptor messenger RNA expression in human benign prostatic hyperplasia: detection, localization, and modulation with a long-acting gonadotropin-releasing hormone agonist

We have analyzed human benign prostatic hyperplastic (BPH) tissue derived from eight radical prostatectomy specimens from patients with prostate cancer for the expression of the estrogen receptor (ER) messenger RNA. Four of the eight patients received a long-acting gonadotropin-releasing hormone agonist (GnRHa) for 4 months prior to surgery. An RNase protection assay utilizing six riboprobes spanning most of the ER protein-coding sequences demonstrated expression of the ER mRNA in human BPH tissue. A comparison of ER mRNA expression in four patients who had received 4 months pretreatment with the GnRHa vs. the four untreated patients suggested that there is upregulation of ER mRNA expression with the GnRHa treatment. The combined techniques of in situ hybridization and immunocytochemistry localized the ER mRNA expression to the prostatic basal epithelial cells and stroma. We conclude that ER mRNA is expressed in human BPH tissue and that this expression is modulated by treatment with a long-acting GnRH agonist.

Tissue-specific expression of Ran isoforms in the mouse

Ran genes encode a family of well-conserve small nuclear GTPases (Ras-related nuclear proteins), whose function is implicated in both normal cell cycle progression and the transport of RNA and proteins between the nucleus and the cytoplasm. Previous studies of Ran proteins have utilized cell-free systems, yeasts, and cultured mammalian cells. We have now characterized patterns of Ran gene expression in the mouse. Serum starvation suppressed Ran gene transcription in mouse 3T3 cells. Ran mRNA reappeared in cells within 3 h after refeeding. A single Ran mRNA species was detected at low levels in most somatic tissues of the adult mouse. In testis, this Ran mRNA was abundant, as were other larger transcripts. Analysis of testis-derived Ran cDNA clones revealed the presence of two transcripts, one specifying an amino acid sequence identical to that of human Ran/TC4 and one specifying an amino acid sequence 94% identical. Northern blotting and reverse transcriptase-PCR assays with oligonucleotide probes and primers specific for each transcript demonstrated that the isoform identical to Ran/TC4 was expressed in both somatic tissues and testis, while the variant form was transcribed only in testis. The existence of tissue-specific Ran isoforms may help to rationalize the diverse roles suggested for Ran by previous biochemical studies.

Effects of mutant Ran/TC4 proteins on cell cycle progression

Ran/TC4, a member of the RAS gene superfamily, encodes an abundant nuclear protein that binds and hydrolyzes GTP. Transient expression of a Ran/TC4 mutant protein deficient in GTP hydrolysis blocked DNA replication, suggesting a role for Ran/TC4 in the regulation of cell cycle progression. To test this possibility, we exploited an efficient transfection system, involving the introduction of cDNAs in the pMT2 vector into 293/Tag cells, to analyze phenotypes associated with mutant and wild-type Ran/TC4 expression. Expression of a Ran/TC4 mutant protein deficient in GTP hydrolysis inhibited proliferation of transfected cells by arresting them predominantly in the G2, but also in the G1, phase of the cell cycle. Deletion of an acidic carboxy-terminal hexapeptide from the Ran/TC4 mutant did not alter its nuclear localization but did block its inhibitory effect on cell cycle progression. These data suggest that normal progression of the cell cycle is coupled to the operation of a Ran/TC4 GTPase cycle. Mediators of this coupling are likely to include the nuclear regulator of chromosome condensation 1 protein and the mitosis-promoting factor complex.

Characterization of proteins that interact with the cell-cycle regulatory protein Ran/TC4

The human Ras-related nuclear protein Ran/TC4 (refs 1-4) is the prototype of a well conserved family of GTPases that can regulate both cell-cycle progression and messenger RNA transport. Ran has been proposed to undergo tightly controlled cycles of GTP binding and hydrolysis, to operate as a GTPase switch whose GTP- and GDP-bound forms interact differentially with regulators and effectors. One known regulator, the protein RCC1 (refs 12, 13), interacts with Ran to catalyse guanine nucleotide exchange, and both RCC1 and Ran are components of an intrinsic checkpoint control that prevents the premature initiation of mitosis. To test and extend the GTPase-switch model, we searched for a Ran-specific GTPase-activating protein (GAP), and for putative effectors (proteins that interact specifically with Ran/TC4-GTP). We report here the identification of a Ran GAP and its use to characterize the GTP-hydrolysing properties of mutant Ran proteins, and the identification and cloning of a binding protein specific for Ran/TC4-GTP.

Enhanced androgen sensitivity in serum-free medium of a subline of the LNCaP human prostate cancer cell line

The LNCaP-Fast Growing Colony (FGC) human prostate cancer cell line proliferates in response to the addition of dihydrotestosterone (DHT) 10(-10)-10(-8) M in charcoal-stripped serum-supplemented media. LNCaP-FGC cells will not attach or proliferate in serum-free conditions. LNCaP-FGC stock cultures were maintained in medium supplemented with 10% FBS and added DHT (10(-9) M) for > 25 passages (6 months). The resultant subline was designated as LNCaP-ss (supersensitive) because of its ability to attach in serum-free medium and to proliferate in response to very low levels of DHT. LNCaP-ss cells were grown in serum-free medium and proliferation assessed after 2, 3, 5, and 7 days' treatment with DHT. Significant enhancement of growth was demonstrated after 7 days' treatment with DHT over a wide range of concentrations (DHT 10(-15)-10(-7) M) with maximal stimulation (3 x control, p < .001) noted with DHT 10(-14) M. Changing the medium during the course of the experiment decreased, but did not eliminate, the DHT-induced cellular proliferation. Scatchard analysis of binding studies with LNCaP-ss cells revealed that both the Kd for the androgen receptor (AR) and the number of AR sites/cell were similar to the corresponding values reported for the parental line. AR mRNA levels in LNCaP-ss cells, as measured by RNase protection assay, were significantly down-regulated by 7 days' treatment with DHT 10(-15), 10(-13), and 10(-9) M.(ABSTRACT TRUNCATED AT 250 WORDS)

Ran/TC4: a small nuclear GTP-binding protein that regulates DNA synthesis

Ran/TC4, first identified as a well-conserved gene distantly related to H-RAS, encodes a protein which has recently been shown in yeast and mammalian systems to interact with RCC1, a protein whose function is required for the normal coupling of the completion of DNA synthesis and the initiation of mitosis. Here, we present data indicating that the nuclear localization of Ran/TC4 requires the presence of RCC1. Transient expression of a Ran/TC4 protein with mutations expected to perturb GTP hydrolysis disrupts host cell DNA synthesis. These results suggest that Ran/TC4 and RCC1 are components of a GTPase switch that monitors the progress of DNA synthesis and couples the completion of DNA synthesis to the onset of mitosis.

Mobilization of calcium from intracellular stores as one of the mechanisms underlying the antiopioid effect of cholecystokinin octapeptide

In enzymatically dissociated brain cells prepared from neonatal rats, KCl produced a significant increase in [Ca2+]i and this increase could be prevented by verapamil or nifedipine, known to block voltage-sensitive calcium channels. The opioid receptor agonists ohmefentanyl (OMF, mu agonist), [D-Pen2,D-Pen5]enkephalin (DPDPE, delta agonist), and 66A-078 (kappa agonist) produced a marked suppression of the Ca2+ influx induced by high K+ depolarization. The suppressive effect of OMF, DPDPE, and 66A-078 on the high K(+)-induced increase in [Ca2+]i was markedly reversed by their respective antagonists beta-funaltrexamine (beta-FNA), ICI174864, and nor-binaltorphimine (nor-BNI). Cholecystokinin octapeptide (CCK-8), at concentrations of 0.3, 3.0, and 30 nM, dose-dependently mobilized Ca2+ from intracellular stores. While CCK-8 30 nM did not affect significantly the increase of [Ca2+]i following high K+, it did reverse the suppression of the high K(+)-induced increase in [Ca2+]i by the mu agonist OMF and the kappa agonist 66A-078, but not that by the delta agonist DPDPE. The results suggested that while opioid ligands suppress [Ca2+]i by blocking voltage-operated Ca2+ influx, the antiopioid effect of CCK-8 seems to be operated via mobilization of Ca2+ from intracellular stores.

The effect of androgen, estrogen, and growth factors on the proliferation of cultured fibroblasts derived from human fetal and adult prostates

Stromal enlargement plays a key role in the development of benign prostatic hypertrophy in humans. Human prostatic fibroblasts were obtained from fetal and adult prostates and characterized as to their androgen and estrogen receptor status and growth in response to dihydrotestosterone (DHT), estradiol (E2), hydroxyflutamide (OH-FLU), hydrocortisone, basic fibroblast growth factor (bFGF), and epidermal growth factor (EGF). In addition, the ability of hormones and growth factors to induce the messenger RNA (mRNA) for the c-fos protooncogene was assessed as a measure of the early, direct effects of these compounds on cellular proliferation. Nuclear androgen receptors were demonstrable by immunocytochemistry in both fetal and adult cells. Nuclear estrogen receptor staining was negative. Neither E2 nor hydrocortisone increased cellular proliferation. Both EGF and bFGF did increase cellular growth. DHT (10(-8)-10(-7) M) had a significant stimulatory effect on cell growth only in serum-free media. OH-FLU addition enhanced DHT induced proliferation. Changing the media during the course of the experiment obliterated the stimulatory effect of DHT. Both EGF (10 ng/ml) and bFGF (20 ng/ml) increased the mRNA for the c-fos protooncogene. DHT (10(-7) M) did not induce the mRNA for c-fos. We conclude that EGF, bFGF, and DHT (especially in combination with OH-FLU) increase the proliferation of human prostatic fetal and adult fibroblasts in vitro. E2 has no effect on fibroblast proliferation. The stimulatory effects of EGF and bFGF are direct, whereas the effect of DHT appears to be indirect, possibly mediated via the increased production and/or secretion of growth factors.

Molecular analysis of a patient with neurofibromatosis 1 and achondroplasia

The gene for von Recklinghausen neurofibromatosis (NF1) is on proximal 17q; the location of the gene for achondroplasia (ACH) is unknown. We have begun a molecular analysis of a patient with mental retardation, NF1 and ACH, a clinical presentation suggestive of a contiguous gene syndrome. In addition, this individual has a 47,XYY chromosome constitution. To define a possible chromosome 17 deletion, we investigated the copy number of DNA sequences linked to NF1 with conventional and pulsed-field gel electrophoresis (PFGE). We found no evidence for a deletion on chromosome 17. These results make it unlikely that this patient harbors a single deletion in the NF1 region causing both NF1 and ACH and suggest different mechanisms for the de novo occurrence of 2 autosomal dominant disorders in this individual.