Steen Dissing - Academia.edu (original) (raw)

Papers by Steen Dissing

Cancer Cell, 2006

Cancer metastases are commonly found in the lymphatic system. Like tumor blood angiogenesis, stim... more Cancer metastases are commonly found in the lymphatic system. Like tumor blood angiogenesis, stimulation of tumor lymphangiogenesis may require the interplay of several tumor-derived growth factors. Here we report that members of the PDGF family act as lymphangiogenic factors. In vitro, PDGF-BB stimulated MAP kinase activity and cell motility of isolated lymphatic endothelial cells. In vivo, PDGF-BB potently induced growth of lymphatic vessels. Expression of PDGF-BB in murine fibrosarcoma cells induced tumor lymphangiogenesis, leading to enhanced metastasis in lymph nodes. These data demonstrate that PDGF-BB is an important growth factor contributing to lymphatic metastasis. Thus, blockage of PDGF-induced lymphangiogenesis may provide a novel approach for prevention and treatment of lymphatic metastasis.

Physiology, 1993

Digital image processing technique on fura-2-loaded acinar cells from exocrine gland end pieces s... more Digital image processing technique on fura-2-loaded acinar cells from exocrine gland end pieces shows that, on receptor activation, intracellular free Ca2+ concentration rises rapidly at the basolateral and luminal membranes. This is consistent with a model in which K+ channels at basolateral membranes and Cl- channels at luminal membranes are activated simultaneously.

Pflügers Archiv: European Journal of Physiology, 2000

The activity of nitric oxide synthase (NOS) in rat parotid acinar cells was measured using a newl... more The activity of nitric oxide synthase (NOS) in rat parotid acinar cells was measured using a newly synthesized fluorescent NO indicator DAF-2/DA. Our results show that NO production is most effectively stimulated by activation of the beta-adrenergic receptor, and to a minor extent by substance P (SP). NO activates the production of cGMP, an intracellular messenger that has been shown to release Ca2+ from ryanodine-sensitive intracellular stores. We found that cGMP is also able to release Ca2+ from ryanodine-insensitive intracellular stores. Our data show that a rise in the cGMP concentration induces inositol 1,4,5-trisphosphate [Ins(1,4,5)P3] synthesis and Ca2+ release from intracellular stores.

Diabetes, Jul 1, 1995

In the insulin-secreting p-cell line (STC3, stimulation with 11.2 mmol/1 glucose caused a rise in... more In the insulin-secreting p-cell line (STC3, stimulation with 11.2 mmol/1 glucose caused a rise in the intracellular free Ca 2+ concentration ([Ca 2+ ]i) in only 18% of the tested cells. The number of glucose-responsive cells increased after pretreatment of the cells with glucagon-like peptide I (GLP-I)(7-36)amide and at 10" 11 mol/1; 84% of the cells responded to glucose with a rise in [Ca 2+ ]j. GLP-I(7-36)amide induces a rapid increase in [Ca 2+ ] i only in cells exposed to elevated glucose concentrations (^5.6 mmol/ 1). The action of GLP-I(7^36)amide and forskolin involved a 10-fold increase in cytoplasmic cAMP concentration and was mediated by activation of protein kinase A. It was not associated with an effect on the membrane potential but required some (small) initial entry of Ca 2+ through voltage-dependent L-type Ca 2+ channels, which then produced a further increase in [Ca 2+ ]i by mobilization from intracellular stores. The latter effect reflected Ca 2+-induced Ca 2+ release and was blocked by ryanodine. Similar increases in [Ca 2+ ]i were also observed in voltageclamped cells, although there was neither activation of a background (Ca 2+-permeable) inward current nor enhancement of the voltage-dependent L-type Ca 2+ current. These observations are consistent with GLP-I(7-36) amide inducing glucose sensitivity by promoting mobilization of Ca 2+ from intracellular stores. We propose that this novel action of GLP-I(7-36)amide represents an important factor contributing to its insulinotropic action.

Biochemical Journal, 1995

The effect of extracellular ATP on the intracellular free Ca2+ concentration ([Ca2+]i) and inosit... more The effect of extracellular ATP on the intracellular free Ca2+ concentration ([Ca2+]i) and inositol phosphate production following stimulation with the muscarinic cholinergic agonist acetylcholine (ACh) was investigated in isolated rat parotid acinar cells. Stimulation of rat parotid acinar cells with ATP4- results in a rise in [Ca2+]i that is due to influx of extracellular Ca2+ and mobilization of Ca2+ from intracellular stores. Stimulation with purinergic agonists revealed that both influx as well as Ca2+ release from intracellular stores was mediated through activation of P2z receptors. The Ca2+ mobilization from intracellular stores was due to production of Ins(1,4,5)P3 and was inhibited by U73122, an inhibitor of phospholipase C-coupled processes. Under Ca(2+)-free conditions ATP4- caused a dose-dependent inhibition (IC50 = 8 microM) of the ACh-evoked Ca2+ release. The inhibitory effect of ATP4- is due to activation of the P2z purinoceptors, which results in a strong reduction ...

Comparative Biochemistry and Physiology Part A: Physiology, 1988

Secretory responses of parotid acini occurring within f# set following chohnergic stimulation wer... more Secretory responses of parotid acini occurring within f# set following chohnergic stimulation were characterized. 1. Measurement of membrane potentials by means of the fluorescent dye disc,-(S) revealed a value of _-59 mV, which remained unaffected on stimulation. 2. Stimulation caused a rapid net loss of 4*Kf that was strongly inhibited by the "maxi" K+-channel inhibitor "charybdotoxin" present in scorpion venom. 3. It was calculated that the number of open "maxi" K*-channels per cell was-40 in the unstimulated state and-3000 in the stimulated state. 4. Stimulation caused a transient decrease in the acinar ATP content. 5. Intracellular pH (pH;) measured by means of the fluorescent dye, BCECF, was dependent upon the presence of extradelluiar 'HCO; as well as Na+. Under physiological conditions pH, was 7.27 and stimulation caused a transient decrease of 0.1 pH units due to HCO, efflux. The decrease was followed by pH, recovery mediated by a Na+/H+ exchange mechanism.

The red cell Na/K pump is known to continue to extrude Na when both Na and K are removed from the... more The red cell Na/K pump is known to continue to extrude Na when both Na and K are removed from the external medium. Because this ouabainsensitive flux occurs in the absence of an exchangeable cation, it is referred to as uncoupled Na efflux. This flux is also known to be inhibited by 5 mM Na o but to a lesser extent than that inhibitable by ouabain. Uncoupled Na efflux via the Na/K pump therefore can be divided into a Nao-sensitive and Nao-insensitive component. We used DIDS-treated, SO4-equilibrated human red blood cells suspended in HEPES-buffered (pH o 7.4) MgSO 4 or (Tris)~SO4, in which we measured ~2Na efflux, SSso4 efflux, and changes in the membrane potential with the fluorescent dye, diS-C s (5). A principal finding is that uncoupled Na efflux occurs electroneutrally, in contrast to the pump's normal electrogenic operation when exchanging Na i for K o. This electroneutral uncoupled efflux of Na was found to be balanced by an effiux of cellular anions. (We were unable to ...

The FASEB Journal, Apr 1, 2016

The incretine GLP-1 enhances insulin release and thereby causes a diminished blood glucose peak i... more The incretine GLP-1 enhances insulin release and thereby causes a diminished blood glucose peak in response to food intake. We explored the potential roles of GLP-1 in vascular function by studying...

Supplementary information for the paper "The calcium-sensing receptor is essential for calci... more Supplementary information for the paper "The calcium-sensing receptor is essential for calcium and bicarbonate sensitivity in human spermatozoa"

Proceedings of the National Academy of Sciences, 2009

VEGF coordinates complex regulation of cellular regeneration and interactions between endothelial... more VEGF coordinates complex regulation of cellular regeneration and interactions between endothelial and perivascular cells; dysfunction of the VEGF signaling system leads to retinopathy. Here, we show that systemic delivery of VEGF and placental growth factor (PlGF) by protein implantation, tumors, and adenoviral vectors ablates pericytes from the mature retinal vasculature through the VEGF receptor 1 (VEGFR1)-mediated signaling pathway, leading to increased vascular leakage. In contrast, we demonstrate VEGF receptor 2 (VEGFR2) is primarily expressed in nonvascular photoreceptors and ganglion cells. Moreover, blockade of VEGFR1 but not VEGFR2 significantly restores pericyte saturation in mature retinal vessels. Our findings link VEGF and PlGF to cancer-associated retinopathy, reveal the molecular mechanisms of VEGFR1 ligand-mediated retinopathy, and define VEGFR1 as an important target of antiangiogenic therapy for treatment of retinopathy.

International Journal of Andrology, 2012

Vitamin D (VD) is important for male reproduction in mammals and the VD receptor (VDR) and VD-met... more Vitamin D (VD) is important for male reproduction in mammals and the VD receptor (VDR) and VD-metabolizing enzymes are expressed in human spermatozoa. The VD-inactivating enzyme CYP24A1 titrates the cellular responsiveness to VD, is transcriptionally regulated by VD, and has a distinct expression at the sperm annulus. Here, we investigated if CYP24A1 expression serves as a marker for VD metabolism in spermatozoa, and whether CYP24A1 expression was associated with semen quality. We included 130 men (53 healthy young volunteers and 77 subfertile men) for semen analysis and immunocytochemical (ICC) detection of CYP24A1. Another 40 men (22 young, 18 subfertile) were tested for in vitro effects of 1,25(OH)(2)D(3) on intracellular calcium concentration ([Ca(2+)](i)) and sperm motility. Double ICC staining showed that CYP24A1 and VDR were either concomitantly expressed or absent in 80% of the spermatozoa from young men. The median number of CYP24A1-expressing spermatozoa was 1% in subfertile men and thus significantly (p &amp;amp;amp;amp;amp;lt; 0.0005) lower than 25% in spermatozoa from young men. Moreover, CYP24A1 expression correlated positively with total sperm count, -concentration, -motility and -morphology (all p &amp;amp;amp;amp;amp;lt; 0.004), and the percentage of CYP24A1-positive spermatozoa increased (15 vs. 41%, p &amp;amp;amp;amp;amp;lt; 0.0005) after percoll-gradient-centrifugation. We noticed that the presence of &amp;amp;amp;amp;amp;gt;3% CYP24A1-positive spermatozoa distinguished young men from subfertile men with a sensitivity of 66.0%, a specificity of 77.9% and a positive predictive value of 98.3%. Functional studies revealed that 1,25(OH)(2)D(3) increased [Ca(2+)](i) and sperm motility in young healthy men, while 1,25(OH)(2)D(3) was unable to increase motility in subfertile patients. In conclusion, we suggest that CYP24A1 expression at the annulus may serve as a novel marker of semen quality and an objective proxy for sperm function.

Acta Physiologica Scandinavica, 2002

The aim of the present study was to investigate the physiological role of nitric oxide (NO) in me... more The aim of the present study was to investigate the physiological role of nitric oxide (NO) in mediating secretory processes in rat lacrimal acinar cells. In addition, we wanted to determine whether the acinar cells possess endogenous nitric oxide synthase (NOS) activity by measuring NO production using the fluorescent NO indicator 4,5-diaminofluorescein (DAF-2). We initiated investigations by adding NO from an external source by means of the NO-donor, S-nitroso-N-acetyl-penicillamine (SNAP). Cellular concentrations of cyclic guanosine 5'-phosphate (cGMP) ([cGMP]) were measured by radioimmunoassay (RIA), and we found that SNAP induced a fast increase in the [cGMP], amounting to 350% of the [cGMP] in resting cells. Moreover, addition of SNAP and elevating [cGMP] in fura-2 loaded lacrimal acinar cells, resulted in a cGMP-dependent protein kinase-mediated release of Ca2+ from intracellular stores, leading to a rise in the intracellular free Ca2+ concentration ([Ca2+]i). The Mn2+ quenching studies revealed that the Ca2+ release was not accompanied by Ca2+ influx. Finally, we demonstrate that lacrimal acinar cells possess endogenous NOS activity, which is activated by beta-adrenergic stimulation and not by a rise in [Ca2+]i alone. We show that in rat lacrimal acinar cells, NO and cGMP induce Ca2+ release from intracellular stores via G kinase activation. However, the changes in [Ca2+]i are relatively small, suggesting that this pathway plays a modulatory role in Ca2+ signalling, thus not by itself causing fast transient increases in [Ca2+]i. In addition, we suggest that endogenously produced NO activated by beta-adrenergic receptor stimulation, plays an important role in signalling to the surrounding tissue.

Journal of Oral Pathology and Medicine, 2000

We have characterised the innervation pattern and intracellular Ca 2π-signalling in labial saliva... more We have characterised the innervation pattern and intracellular Ca 2π-signalling in labial salivary glands (LSG) of 16 patients with primary Sjögren's syndrome (pSS) and 27 healthy controls. Numerous immunoreactive nerve fibers (IRF) containing vasoactive intestinal peptide (VIP) and pituitary adenylate cyclase activating peptide (PACAP) were found around acini, ducts and blood vessels. Substance P (SP)-, neuropeptide Y-, tyrosine hydroxylase-and nitric oxide synthase-IRF were mainly surrounding ducts and blood vessels. The majority of pSS patients had inflamed LSG and the presence of focal lymphocytic infiltrates (FI) were more frequent and pronounced as compared with healthy controls. In areas with normal or diffusely inflamed LSG tissue, pSS patients demonstrated the same distribution of IRF as healthy controls with similar histology. However, IRF were absent in central areas of FI both in pSS and age-matched healthy controls. Although all pSS patients had hyposalivation, stimulation with acetylcholine, norepinephrine, phenylephrine, isoproterenol, VIP, PACAP, SP, adenosine 5ø-triphosphate and uridine 5ø-triphosphate induced the same increase in the intracellular free Ca 2π concentration in LSG acini from both pSS patients and healthy controls, indicating the presence of functional receptor systems in vitro.

The Journal of Clinical Endocrinology & Metabolism, 2020

Context The calcium-sensing receptor (CaSR) is essential to maintain a stable calcium concentrati... more Context The calcium-sensing receptor (CaSR) is essential to maintain a stable calcium concentration in serum. Spermatozoa are exposed to immense changes in concentrations of CaSR ligands such as calcium, magnesium, and spermine during epididymal maturation, in the ejaculate, and in the female reproductive environment. However, the role of CaSR in human spermatozoa is unknown. Objective This work aimed to investigate the role of CaSR in human spermatozoa. Methods We identified CaSR in human spermatozoa and characterized the response to CaSR agonists on intracellular calcium, acrosome reaction, and 3′,5′-cyclic adenosine 5′-monophosphate (cAMP) in spermatozoa from men with either loss-of-function or gain-of-function mutations in CASR and healthy donors. Results CaSR is expressed in human spermatozoa and is essential for sensing extracellular free ionized calcium (Ca2+) and Mg2+. Activators of CaSR augmented the effect of sperm-activating signals such as the response to HCO3– and the a...

Reproduction, 2021

Ca2+ signalling controls human sperm functions necessary for successful fertilization. Multiple e... more Ca2+ signalling controls human sperm functions necessary for successful fertilization. Multiple endocrine-disrupting chemicals have been found to activate the CatSper Ca2+ channel and thereby interfering with Ca2+ signalling in human sperm. Finasteride is prescribed to men in the fertile age to treat hair loss and its use has been associated with impaired male fertility. Due to the structural relatedness of finasteride to the endogenous CatSper ligand progesterone, this study aimed to investigate whether finasteride affects human sperm in a progestogen-like manner. The effect of finasteride on Ca2+ signalling via CatSper in human sperm was investigated in cell suspensions by single-cell imaging. Additionally, effects on sperm penetration into viscous medium and acrosome reaction were assessed. Finasteride alone caused a minor transient rise in the intracellular, free Ca2+ concentration ([Ca2+]i) at physiologically relevant concentrations. Ca2+ signals induced by PGE1 were inhibited ...