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Torday JS, Miller WB. The resolution of ambiguity as the basis for life: A cellular bridge between Western reductionism and Eastern holism. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2017; 131:288-297. [PMID: 28743585 DOI: 10.1016/j.pbiomolbio.2017.07.013] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/14/2017] [Revised: 07/12/2017] [Accepted: 07/21/2017] [Indexed: 01/08/2023]
Abstract
Boundary conditions enable cellular life through negentropy, chemiosmosis, and homeostasis as identifiable First Principles of Physiology. Self-referential awareness of status arises from this organized state to sustain homeostatic imperatives. Preferred homeostatic status is dependent upon the appraisal of information and its communication. However, among living entities, sources of information and their dissemination are always imprecise. Consequently, living systems exist within an innate state of ambiguity. It is presented that cellular life and evolutionary development are a self-organizing cellular response to uncertainty in iterative conformity with its basal initiating parameters. Viewing the life circumstance in this manner permits a reasoned unification between Western rational reductionism and Eastern holism.
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Affiliation(s)
- John S Torday
- Department of Pediatrics, Harbor-UCLA Medical Center, Torrance, CA 90502, USA.
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Martin TJ. Parathyroid Hormone-Related Protein, Its Regulation of Cartilage and Bone Development, and Role in Treating Bone Diseases. Physiol Rev 2016; 96:831-71. [DOI: 10.1152/physrev.00031.2015] [Citation(s) in RCA: 99] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Although parathyroid hormone-related protein (PTHrP) was discovered as a cancer-derived hormone, it has been revealed as an important paracrine/autocrine regulator in many tissues, where its effects are context dependent. Thus its location and action in the vasculature explained decades-long observations that injection of PTH into animals rapidly lowered blood pressure by producing vasodilatation. Its roles have been specified in development and maturity in cartilage and bone as a crucial regulator of endochondral bone formation and bone remodeling, respectively. Although it shares actions with parathyroid hormone (PTH) through the use of their common receptor, PTHR1, PTHrP has other actions mediated by regions within the molecule beyond the amino-terminal sequence that resembles PTH, including the ability to promote placental transfer of calcium from mother to fetus. A striking feature of the physiology of PTHrP is that it possesses structural features that equip it to be transported in and out of the nucleus, and makes use of a specific nuclear import mechanism to do so. Evidence from mouse genetic experiments shows that PTHrP generated locally in bone is essential for normal bone remodeling. Whereas the main physiological function of PTH is the hormonal regulation of calcium metabolism, locally generated PTHrP is the important physiological mediator of bone remodeling postnatally. Thus the use of intermittent injection of PTH as an anabolic therapy for bone appears to be a pharmacological application of the physiological function of PTHrP. There is much current interest in the possibility of developing PTHrP analogs that might enhance the therapeutic anabolic effects.
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Affiliation(s)
- T. John Martin
- St Vincent's Institute of Medical Research, Department of Medicine, University of Melbourne, St Vincent's Hospital, Melbourne, Australia
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Ye GJC, Nesmith AP, Parker KK. The role of mechanotransduction on vascular smooth muscle myocytes' [corrected] cytoskeleton and contractile function. Anat Rec (Hoboken) 2015; 297:1758-69. [PMID: 25125187 DOI: 10.1002/ar.22983] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2014] [Accepted: 06/06/2014] [Indexed: 12/29/2022]
Abstract
Smooth muscle (SM) exhibits a highly organized structural hierarchy that extends over multiple spatial scales to perform a wide range of functions at the cellular, tissue, and organ levels. Early efforts primarily focused on understanding vascular SM (VSM) function through biochemical signaling. However, accumulating evidence suggests that mechanotransduction, the process through which cells convert mechanical stimuli into biochemical cues, is requisite for regulating contractility. Cytoskeletal proteins that comprise the extracellular, intercellular, and intracellular domains are mechanosensitive and can remodel their structure and function in response to external mechanical cues. Pathological stimuli such as malignant hypertension can act through the same mechanotransductive pathways to induce maladaptive remodeling, leading to changes in cellular shape and loss of contractile function. In both health and disease, the cytoskeletal architecture integrates the mechanical stimuli and mediates structural and functional remodeling in the VSM.
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Affiliation(s)
- George J C Ye
- Disease Biophysics Group, Wyss Institute for Biologically Inspired Engineering and the School of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts
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Burgazli KM, Foerster N, Meriçliler M, Chasan R, Parahuleva M, Erdogan A. Effects of parathyroid hormone-related peptide on the large conductance calcium-activated potassium channel and calcium homeostasis in vascular smooth muscle cells. Postgrad Med 2014; 126:76-85. [PMID: 24685970 DOI: 10.3810/pgm.2014.03.2742] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
AIM To demonstrate the impact of the parathyroid hormone-related peptide (PTHrP) on the large conductance calcium-activated potassium (BKCa) channels in vascular smooth muscle cells (VSMC) and hyperpolarization of the cell membrane and its dependence on calcium. MATERIALS AND METHODS VSMC were isolated from rat aorta and further subcultured. Four experiments were conducted in calcium-release measurements and each of them consisted of a control group, PTHrP, chemical substance, and PTHrP + chemical substance. Chemical substances used were: iberiotoxin, xestospongin C, xestospongin D, and thapsigargin, respectively. Fura-2 imaging was used to determine changes in calcium release of VSMC. In membrane-potential experiments, groups were designed similarly to the Fura-2 imaging experiments: iberiotoxin, BAPTA, and xestospongin D were added, in respective order. Changes in the membrane potential were examined using the fluorescence dye (DiBAC). RESULTS Given in a dose between 0.01 and 1.0 μmol/L, PTHrP caused a concentration-dependent decrease in fluorescence intensity, with a maximum effect at 0.5 μmol/L. The decrease, therefore, demonstrated a PTHrP-induced hyperpolarization of the VSMC. The effect was blocked by use of iberiotoxin (100 nmol/L), a highly selective inhibitor of BKCa. Furthermore, when the calcium chelator BAPTA (10 μmol/L) was added, there was a significant reduction in PTHrP-induced hyperpolarization. Use of PTHrP (0.5 μmol/L) also decreased the fluorescence intensity of the indicator for intracellular calcium, Fura-2AM (a membrane-permeable derivative of Fura 2). This effect was re-blocked by use of iberiotoxin. Xestospongin C (3 μmol/L) and xestospongin D (6 μmol/L), both inhibitors of the inositol 1,4,5 trisphosphate-triggered calcium release, inhibited the effects of PTHrP. Additionally, thapsigargin (1 μmol/L), a sarcoplasmic/endoplasmic reticulum Ca2+-ATPase inhibitor, inhibited the effect of PTHrP. CONCLUSION The results of our study show that PTHrP induces hyperpolarization and activates BKCa in VSMC. The activation of BKCa channels is calcium dependent; activation is linked to the inositol 1,4,5 trisphosphate-triggered calcium release and is also dependent on the endo/sarcoplasmic reticulum calcium pump.
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Affiliation(s)
- Kamil Mehmet Burgazli
- Wuppertal Department of Internal Medicine and Angiology, Wuppertal Research and Medical Center, Wuppertal, Germany.
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Guelcher SA, Sterling JA. Contribution of bone tissue modulus to breast cancer metastasis to bone. CANCER MICROENVIRONMENT 2011; 4:247-59. [PMID: 21789687 DOI: 10.1007/s12307-011-0078-3] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/11/2011] [Accepted: 07/08/2011] [Indexed: 01/16/2023]
Abstract
Certain tumors, such as breast, frequently metastasize to bone where they can induce bone destruction. Currently, it is well-accepted that the tumor cells are influenced by other cells and growth factors present in the bone microenvironment that lead to tumor-induced bone disease. Over the past 20 years, many groups have studied this process and determined the major contributing factors; however, these results do not fully explain the changes in gene expression and cell behavior that occur when tumor cells metastasize to bone. More recently, groups studying metastasis from soft tissue sites have determined that the rigidity of the microenvironment, which increases during tumor progression in soft tissue, can regulate tumor cell behavior and gene expression. Therefore, we began to investigate the role of the rigid bone extracellular matrix in the regulation of genes that stimulate tumor-induced bone disease. We found that the rigidity of bone specifically regulates parathyroid hormone-related protein (PTHrP) and Gli2 expression in a transforming growth factor β (TGF-β) and mechanotransduction-dependent mechanism. In this review, we summarize the mechanotransduction signaling pathway and how this influences TGF-β signaling and osteolytic gene expression.
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Affiliation(s)
- Scott A Guelcher
- Department of Chemical and Biomolecular Engineering, Vanderbilt University, 2400 Highland Avenue, 107 Olin Hall, Nashville, TN, 37235-1604, USA,
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Abstract
Tumors such as breast, lung, and prostate frequently metastasize to bone, where they can cause intractable pain and increase the risk of fracture in patients. When tumor cells metastasize to bone, they interact with the microenvironment to promote bone destruction primarily through the secretion of osteolytic factors by the tumor cells and the subsequent release of growth factors from the bone. Our recent data suggest that the differential rigidity of the mineralized bone microenvironment relative to that of soft tissue regulates the expression of osteolytic factors by the tumor cells. The concept that matrix rigidity regulates tumor growth is well established in solid breast tumors, where increased rigidity stimulates tumor cell invasion and metastasis. Our studies have indicated that a transforming growth factor-β (TGF-β) and Rho-associated kinase (ROCK)-dependent mechanism is involved in the response of metastatic tumor cells to the rigid mineralized bone matrix. In this review, we will discuss the interactions between ROCK and TGF-β signaling, as well as potential new therapies that target these pathways.
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Affiliation(s)
- Julie A. Sterling
- Department of Veterans Affairs: Tennessee Valley Healthcare System (VISN 9), Nashville, TN, USA,
- Department of Cancer Biology, Vanderbilt University Medical Center, 1235 MRB IV, 2222 Pierce Avenue 37232, Nashville, TN 37235, USA
- Center for Bone Biology, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Scott A. Guelcher
- Center for Bone Biology, Vanderbilt University Medical Center, Nashville, TN, USA
- Department of Chemical and Biomolecular Engineering, Vanderbilt University, 2400 Highland Avenue, 107 Olin Hall, Nashville, TN 37235–1604, USA,
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Ruppender NS, Merkel AR, Martin TJ, Mundy GR, Sterling JA, Guelcher SA. Matrix rigidity induces osteolytic gene expression of metastatic breast cancer cells. PLoS One 2010; 5:e15451. [PMID: 21085597 PMCID: PMC2981576 DOI: 10.1371/journal.pone.0015451] [Citation(s) in RCA: 66] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2010] [Accepted: 09/22/2010] [Indexed: 12/16/2022] Open
Abstract
Nearly 70% of breast cancer patients with advanced disease will develop bone metastases. Once established in bone, tumor cells produce factors that cause changes in normal bone remodeling, such as parathyroid hormone-related protein (PTHrP). While enhanced expression of PTHrP is known to stimulate osteoclasts to resorb bone, the environmental factors driving tumor cells to express PTHrP in the early stages of development of metastatic bone disease are unknown. In this study, we have shown that tumor cells known to metastasize to bone respond to 2D substrates with rigidities comparable to that of the bone microenvironment by increasing expression and production of PTHrP. The cellular response is regulated by Rho-dependent actomyosin contractility mediated by TGF-ß signaling. Inhibition of Rho-associated kinase (ROCK) using both pharmacological and genetic approaches decreased PTHrP expression. Furthermore, cells expressing a dominant negative form of the TGF-ß receptor did not respond to substrate rigidity, and inhibition of ROCK decreased PTHrP expression induced by exogenous TGF-ß. These observations suggest a role for the differential rigidity of the mineralized bone microenvironment in early stages of tumor-induced osteolysis, which is especially important in metastatic cancer since many cancers (such as those of the breast and lung) preferentially metastasize to bone.
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Affiliation(s)
- Nazanin S. Ruppender
- Department of Chemical and Biomolecular Engineering, Vanderbilt University, Nashville, Tennessee, United States of America
- Center for Bone Biology, Vanderbilt University Medical Center, Nashville, Tennessee, United States of America
| | - Alyssa R. Merkel
- Center for Bone Biology, Vanderbilt University Medical Center, Nashville, Tennessee, United States of America
- Division of Clinical Pharmacology, Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee, United States of America
| | - T. John Martin
- Center for Bone Biology, Vanderbilt University Medical Center, Nashville, Tennessee, United States of America
- Saint Vincent's Institute, Melbourne, Victoria, Australia
| | - Gregory R. Mundy
- Center for Bone Biology, Vanderbilt University Medical Center, Nashville, Tennessee, United States of America
- Division of Clinical Pharmacology, Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee, United States of America
- Veterans' Affairs Tennessee Valley Healthcare System, Nashville, Tennessee, United States of America
| | - Julie A. Sterling
- Center for Bone Biology, Vanderbilt University Medical Center, Nashville, Tennessee, United States of America
- Veterans' Affairs Tennessee Valley Healthcare System, Nashville, Tennessee, United States of America
- Department of Cancer Biology, Vanderbilt University Medical Center, Nashville, Tennessee, United States of America
| | - Scott A. Guelcher
- Department of Chemical and Biomolecular Engineering, Vanderbilt University, Nashville, Tennessee, United States of America
- Center for Bone Biology, Vanderbilt University Medical Center, Nashville, Tennessee, United States of America
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Immunolocalization of PTHrP in the parotid glands of three rodents species: Clethrionomys glareoulus, Microtus arvalis and white Swiss mice. Folia Histochem Cytobiol 2010; 48:306-10. [PMID: 20675290 DOI: 10.2478/v10042-010-0003-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The current study was inspired by the fact that since 2004 no report had appeared on the occurrence of this peptide in healthy parotid glands of humans and animals. The objective of the current study was to investigate the immunolocalization of PTHrP in the parotid gland of three male rodents: 6 common voles (Microtus arvalis, Pallas, 1779), 6 bank voles (Clethrionomys glareoulus, Schreber, 1780) and 6 white Swiss mice, as well as to find out any species differences in the distribution of this peptide in various types of cells of the parotid gland. Immunocytochemical reactions were performed using the ABC technique with specific rabbit antibodies against human PTHrP (34-53) (CALBIOCHEM), diluted 1:70 and 1:50. We observed positive PTHrP expression in the epithelial cells of the striated duct in all the three animal species. The expression was strong in white mouse and very strong in common vole and bank vole. In all the rodent species studied, the reaction for PTHrP was granular in nature and irregularly distributed in the cytoplasm, being definitely stronger at the base and weaker at the apex of the cells. The PTHrP expression was negative in the epithelium of the intercalated duct, interlobular duct, main excretory duct, as well as in the myoepithelial cells surrounding the excretory ducts or serous acini.
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Landa MS, García SI, Liberjen L, Schuman ML, Finkielman S, Pirola CJ. Parathyroid Hormone-Related Protein Overexpression Decreases Blood Pressure in Spontaneously Hypertensive Rats. Clin Exp Hypertens 2009. [DOI: 10.1081/ceh-57435] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
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Song GJ, Fiaschi-Taesch N, Bisello A. Endogenous parathyroid hormone-related protein regulates the expression of PTH type 1 receptor and proliferation of vascular smooth muscle cells. Mol Endocrinol 2009; 23:1681-90. [PMID: 19574446 DOI: 10.1210/me.2009-0098] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
The PTH type 1 receptor (PTH1R) and PTHrP are expressed in vessels, where they contribute to regulating vascular smooth muscle cell (VSMC) function. Elevated PTHrP levels in VSMC are often associated with hyperplasia. In contrast, exogenous PTHrP, acting through the PTH1R, inhibits VSMC proliferation. In this study, we investigated the regulation of PTH1R expression by endogenous PTHrP and the associated effects on VSMC proliferation. Blocking binding of secreted PTHrP fragments to the PTH1R by treatment with either an antagonist or an antibody against PTHrP, and inhibition of PTHrP expression by small interfering RNA significantly increased PTH1R expression. Interestingly, treatment of the cells with a PTHrP analog (Bpa(1)-PTHrP) that activates the PTH1R without inducing its internalization had the same effect on receptor expression. To examine the association between receptor expression and the antiproliferative effect of N-terminal fragments of PTHrP, VSMC were treated with exogenous PTHrP (1-36) acutely and chronically to induce receptor down-regulation. Stimulation of VSMC with exogenous PTHrP (1-36) significantly reduced cell proliferation during the first 18 h of treatment but was no longer effective after 3 d, a time when PTH1R was down-regulated. In contrast, treatment with the noninternalizing agonist Bpa(1)-PTHrP strongly inhibited cell proliferation at all time points. In conclusion, our study show that PTHrP, after its intracellular processing and secretion, promotes down-regulation of the PTH1R in VSMC, thereby regulating cell proliferation in an auto/paracrine fashion. This regulatory mechanism may have important implication during vascular remodeling, in particular in the development of neointima after arterial injury, where PTHrP overexpression occurs.
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Affiliation(s)
- Gyun Jee Song
- Department of Pharmacology and Chemical Biology, University of Pittsburgh School of Medicine, E1358 Biomedical Science Tower, Pittsburgh, Pennsylvania 15261, USA
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Halapas A, Lembessis P, Mourouzis I, Pantos C, Cokkinos DV, Sourla A, Koutsilieris M. Experimental hyperthyroidism increases expression of parathyroid hormone-related peptide and type-1 parathyroid hormone receptor in rat ventricular myocardium of the Langendorff ischaemia-reperfusion model. Exp Physiol 2007; 93:237-46. [PMID: 17911357 DOI: 10.1113/expphysiol.2007.039594] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Parathyroid hormone-related peptide (PTHrP) is released under ischaemic conditions and it improves contractile function of stunned myocardium. The actions of PTHrP are mediated primarily by the type 1 parathyroid hormone receptor (PTH.1R), while PTHrP and PTH.1R expression levels are increased in ventricular hypertrophy associated with experimental hyperthyroidism. Since chronic administration of thyroxine (T4) improves postischaemic recovery in isolated heart models subjected to ischaemia-reperfusion stress, we tested the hypothesis that experimentally induced hyperthyroidism is associated with elevated expression of PTHrP and PTH.1R in rat myocardium. Hyperthyroid and control male Wistar rats were subjected to ischaemia-reperfusion stress using the Langendorff technique, and the PTHrP and PTH.1R expression was assessed by relative quantitative reverse transcriptase-polymerase chain reaction, Western blot analysis and immunohistochemistry. In the Langendorff model, the recovery of left ventricular developed pressure at the end of the stablization period and 45 min into the reperfusion period was used to assess the cardioprotective actions of T4 administration. Our data show that hyperthyroid animals had increased tolerance to the ischaemia-reperfusion stress and that this was associated with an increase of PTHrP and PTH.1R expression levels compared with those of control animals. In the control animals, the expression of PTHrP was increased 45 min into the reperfusion phase, while the PTH.1R expression pattern was significantly and gradually decreased throughout the ischaemia and reperfusion phases. In the hyperthyroid animals, the PTHrP and PTH.1R expression pattern was significantly higher throughout the ischaemia and reperfusion phases compared with that of control hearts. Our data suggest that increasing levels of PTHrP and PTH.1R expression can mediate, at least in part, the T4 administration-induced cardioprotection in rat ventricular myocardium.
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Affiliation(s)
- Antonios Halapas
- Department of Experimental Physiology, Medical School, University of Athens, 75 Micras Asias Goudi-Athens, 115 27 Greece
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Gao Y, Raj JU. Parathyroid hormone-related protein-mediated responses in pulmonary arteries and veins of newborn lambs. Am J Physiol Lung Cell Mol Physiol 2005; 289:L60-6. [PMID: 15749740 DOI: 10.1152/ajplung.00411.2004] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
PTHrP has important roles in lung development and function. Here we determined the vasomotor responses of isolated pulmonary arteries and veins of newborn and adult sheep to PTHrP. In vessels constricted with endothelin-1, PTHrP (PTHrP 1-34) caused greater relaxation of veins than of arteries. In both vessel types, relaxation to the peptide was less in adult than in newborn vessels. In newborn lambs, PTHrP-induced relaxation was not affected by endothelium removal, inhibition of eNOS, or inhibition of adenylyl cyclases by SQ-22536. However, relaxation was attenuated by 4-aminopyridine, inhibitor of voltage-dependent potassium channels, in both arteries and veins, and by charybdotoxin, inhibitor of calcium-activated potassium channels, in veins. When vessels were saturated with 8-BrcAMP (3 x 10(-4) M), to eliminate relaxation mediated by endogenous cAMP, PTHrP-induced relaxation was partially attenuated. In vessels treated with 8-BrcAMP (3 x 10(-4) M), 4-aminopyridine but not charybdotoxin inhibited relaxation induced by PTHrP 1-34 in both arteries and veins. Radioimmunoassay showed that, in the presence of a general phosphodiesterase inhibitor, PTHrP caused a concentration-dependent increase in intracellular cAMP content in arteries and veins, which was largely abolished by SQ-22536. Our results demonstrate that PTHrP is a potent vasodilator of pulmonary vessels, with a greater effect in veins than in arteries. Relaxation induced by the peptide contains both cAMP-dependent and -independent components. In both arteries and veins, voltage-dependent potassium channels mediate the response to PTHrP, at least in part, in a cAMP-independent fashion; and in veins, calcium-activated potassium channels may be stimulated by elevated cAMP levels.
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Affiliation(s)
- Yuansheng Gao
- Division of Neonatology, Los Angeles Biomedical Research Institute, Harbor-UCLA Medical Center, Torrance, CA 90502, USA.
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Noonan WT, Qian J, Stuart WD, Clemens TL, Lorenz JN. Altered renal hemodynamics in mice overexpressing the parathyroid hormone (PTH)/PTH-related peptide type 1 receptor in smooth muscle. Endocrinology 2003; 144:4931-8. [PMID: 12960101 DOI: 10.1210/en.2003-0351] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
PTH-related protein (PTHrP) is an autocrine/paracrine peptide expressed in renal tubules and vasculature and may play an important role in regulating overall renal function. To evaluate the potential role of endogenous PTHrP in the control of renal hemodynamics, we performed clearance measurements in transgenic (TG) mice in which the SMP8 alpha-actin promoter was used to drive overexpression of the PTH/PTHrP type 1 receptor in smooth muscle. In protocol I, responses to acute saline volume expansion (SVE, 0.75 microl/min.g body weight) were measured in TG and nontransgenic (NTG) mice. Mean arterial pressure was significantly lower in TG mice throughout the experiment, and it decreased comparably in both groups in response to SVE. SVE significantly increased effective renal plasma flow in both groups of mice, but the increase was greater in TG than in NTG. Glomerular filtration rate decreased in response to SVE in NTG but did not change in TG animals. In protocol II, renal responses to angiotensin II (ANG II) infusion were determined (0.5 ng/min.g body weight). Baseline arterial pressure was again significantly lower in TG, compared with NTG mice, and TG mice had a blunted pressor response to ANG II. Also, ANG II decreased effective renal plasma flow and glomerular filtration rate in both groups of animals, but the reductions were less in TG than in NTG mice. Our findings indicate that smooth-muscle-specific overexpression of the PTH/PTHrP type 1 receptor resulted in augmentation of the vasodilatory response to SVE and attenuation of the vasoconstrictor response to ANG II. We conclude that endogenous PTHrP can act as an endogenous vasorelaxant factor to modulate renal responses to vasoactive stimuli.
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Affiliation(s)
- William T Noonan
- Department of Molecular and Cellular Physiology, University of Cincinnati College of Medicine, 231 Albert Sabin Way, Cincinnati, Ohio 45267-0576
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Torday JS, Rehan VK. Stretch-stimulated surfactant synthesis is coordinated by the paracrine actions of PTHrP and leptin. Am J Physiol Lung Cell Mol Physiol 2002; 283:L130-5. [PMID: 12060569 DOI: 10.1152/ajplung.00380.2001] [Citation(s) in RCA: 99] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Intrauterine lung development, culminating in physiological pulmonary surfactant production by epithelial type II (TII) cells, is driven by fluid distension through unknown mechanisms. Differentiation of alveolar epithelial and mesenchymal cells is mediated by soluble factors like parathyroid hormone-related protein (PTHrP), a stretch-sensitive TII cell product. PTHrP stimulates pulmonary surfactant production by a paracrine feedback loop mediated by leptin, a soluble product of the mature lipofibroblast (LF). When LFs and TIIs are stretched in coculture, there is a fivefold increase in surfactant phospholipid synthesis that can be "neutralized" by inhibitors of PTHrP or leptin, implicating a paracrine feedback loop in this mechanism. Stretching LFs stimulates PTHrP binding (2.5-fold) and downstream stimulation of triglyceride uptake quantitatively (15-25%) due to upregulation of adipose differentiation-related protein expression. Stretching TII cells increases leptin stimulation of their surfactant phospholipid synthesis threefold, suggesting that retrograde signaling by leptin to TII cells is also stretch sensitive. We conclude that the effect of stretch on alveolar LF and TII differentiation is coordinated by PTHrP, leptin, and their receptors.
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Affiliation(s)
- J S Torday
- Department of Obstetrics and Gynecology, Harbor-University of California Los Angeles Research and Education Institute, Torrance, California 90502, USA.
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Clemens TL, Cormier S, Eichinger A, Endlich K, Fiaschi-Taesch N, Fischer E, Friedman PA, Karaplis AC, Massfelder T, Rossert J, Schlüter KD, Silve C, Stewart AF, Takane K, Helwig JJ. Parathyroid hormone-related protein and its receptors: nuclear functions and roles in the renal and cardiovascular systems, the placental trophoblasts and the pancreatic islets. Br J Pharmacol 2001; 134:1113-36. [PMID: 11704631 PMCID: PMC1573066 DOI: 10.1038/sj.bjp.0704378] [Citation(s) in RCA: 129] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2001] [Accepted: 09/10/2001] [Indexed: 11/09/2022] Open
Abstract
The cloning of the so-called 'parathyroid hormone-related protein' (PTHrP) in 1987 was the result of a long quest for the factor which, by mimicking the actions of PTH in bone and kidney, is responsible for the hypercalcemic paraneoplastic syndrome, humoral calcemia of malignancy. PTHrP is distinct from PTH in a number of ways. First, PTHrP is the product of a separate gene. Second, with the exception of a short N-terminal region, the structure of PTHrP is not closely related to that of PTH. Third, in contrast to PTH, PTHrP is a paracrine factor expressed throughout the body. Finally, most of the functions of PTHrP have nothing in common with those of PTH. PTHrP is a poly-hormone which comprises a family of distinct peptide hormones arising from post-translational endoproteolytic cleavage of the initial PTHrP translation products. Mature N-terminal, mid-region and C-terminal secretory forms of PTHrP are thus generated, each of them having their own physiologic functions and probably their own receptors. The type 1 PTHrP receptor, binding both PTH(1-34) and PTHrP(1-36), is the only cloned receptor so far. PTHrP is a PTH-like calciotropic hormone, a myorelaxant, a growth factor and a developmental regulatory molecule. The present review reports recent aspects of PTHrP pharmacology and physiology, including: (a) the identification of new peptides and receptors of the PTH/PTHrP system; (b) the recently discovered nuclear functions of PTHrP and the role of PTHrP as an intracrine regulator of cell growth and cell death; (c) the physiological and developmental actions of PTHrP in the cardiovascular and the renal glomerulo-vascular systems; (d) the role of PTHrP as a regulator of pancreatic beta cell growth and functions, and, (e) the interactions of PTHrP and calcium-sensing receptors for the control of the growth of placental trophoblasts. These new advances have contributed to a better understanding of the pathophysiological role of PTHrP, and will help to identify its therapeutic potential in a number of diseases.
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Affiliation(s)
- Thomas L Clemens
- Department of Medicine, University of Cincinnati, Cincinnati, Ohio, U.S.A
- Department of Molecular and Cellular Physiology, University of Cincinnati, Cincinnati, Ohio, U.S.A
| | - Sarah Cormier
- INSERM U 426 and Institut Federatif de Recherche ‘Cellules Epitheliales', Faculte de Medecine Xavier Bichat, Paris, France
| | - Anne Eichinger
- Section of Renovascular Pharmacology and Physiology, INSERM E0015-ULP, University Louis Pasteur School of Medicine, Strasbourg, France
| | - Karlhans Endlich
- Institut für Anatomie und Zellbiologie 1, Universität Heidelberg, Heidelberg, Germany
| | - Nathalie Fiaschi-Taesch
- Section of Renovascular Pharmacology and Physiology, INSERM E0015-ULP, University Louis Pasteur School of Medicine, Strasbourg, France
- Division of Endocrinology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, PA 15213, U.S.A
| | - Evelyne Fischer
- Department of Nephrology, University Hospital of Strasbourg, Strasbourg, France
| | - Peter A Friedman
- Department of Pharmacology, University of Pittsburgh School of Medicine, Pittsburgh, U.S.A
- Department of Medicine, University of Pittsburgh School of Medicine, Pittsburgh, U.S.A
| | | | - Thierry Massfelder
- Section of Renovascular Pharmacology and Physiology, INSERM E0015-ULP, University Louis Pasteur School of Medicine, Strasbourg, France
| | - Jérôme Rossert
- INSERM U489 and Departments of Nephrology and Pathology, Paris VI University, France
| | | | - Caroline Silve
- INSERM U 426 and Institut Federatif de Recherche ‘Cellules Epitheliales', Faculte de Medecine Xavier Bichat, Paris, France
| | - Andrew F Stewart
- Division of Endocrinology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, PA 15213, U.S.A
| | - Karen Takane
- Division of Endocrinology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, PA 15213, U.S.A
| | - Jean-Jacques Helwig
- Section of Renovascular Pharmacology and Physiology, INSERM E0015-ULP, University Louis Pasteur School of Medicine, Strasbourg, France
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Curtis NE, King RG, Moseley JM, Ho PW, Rice GE, Wlodek ME. Preterm fetal growth restriction is associated with increased parathyroid hormone-related protein expression in the fetal membranes. Am J Obstet Gynecol 2000; 183:700-5. [PMID: 10992196 DOI: 10.1067/mob.2000.106593] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
OBJECTIVE Parathyroid hormone-related protein has roles in normal fetal growth, placental calcium transport, and vascular tone regulation; these factors are compromised in growth-restricted fetuses. Our objective was to determine whether intrauterine parathyroid hormone-related protein expression was increased in association with fetal growth restriction. STUDY DESIGN The expression of parathyroid hormone-related protein was examined in intrauterine tissues from women with idiopathic fetal growth restriction with preterm (n = 8-10) and term (n = 8-10) gestations and from gestation-matched control subjects. The abundance and immunoreactive content of parathyroid hormone-related protein messenger ribonucleic acid were determined by Northern blot and radioimmunoassay, respectively, in the placenta, amnion, and chorion-decidua. RESULTS The expression of parathyroid hormone-related protein messenger ribonucleic acid was increased in the amnion (placental and reflected) in association with preterm fetal growth restriction (P <.05). Both parathyroid hormone-related protein messenger ribonucleic acid and protein expression were increased in chorion-decidua in association with preterm fetal growth restriction (P <.05). In term gestations both parathyroid hormone-related protein messenger ribonucleic acid and protein expression were greater in amnion over placenta than in reflected amnion (P <.05); these in turn were greater than those in chorion-decidua (P <.05). No significant changes were detected in parathyroid hormone-related protein messenger ribonucleic acid or in protein expression in association with term fetal growth restriction. CONCLUSION Either parathyroid hormone-related protein messenger ribonucleic acid or protein expression, or both, was increased in the fetal membranes in association with fetal growth restriction in preterm but not term gestations, suggesting that parathyroid hormone-related protein may be involved in the pathogenesis of preterm fetal growth restriction.
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Affiliation(s)
- N E Curtis
- Department of Perinatal Medicine, Royal Women's Hospital, Carlton, Australia
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Stuart WD, Maeda S, Khera P, Fagin JA, Clemens TL. Parathyroid hormone-related protein induces G1 phase growth arrest of vascular smooth muscle cells. Am J Physiol Endocrinol Metab 2000; 279:E60-7. [PMID: 10893323 DOI: 10.1152/ajpendo.2000.279.1.e60] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
In this study, we investigated the mechanisms responsible for the growth-inhibitory action of parathyroid hormone-related protein (PTHRP) in A10 vascular smooth muscle cells (VSMC). Fluorescence-activated cell sorting analysis of serum-stimulated VSMC treated with PTHRP or dibutyryl-cAMP (DBcAMP) demonstrated an enrichment of cells in G1 and a reduction in the S phase. Measurement of DNA synthesis in platelet-derived growth factor-stimulated VSMC treated with DBcAMP revealed that cells became refractory to growth inhibition by 12-16 h, consistent with blockade in mid-G1. cAMP treatment blunted the serum-induced rise in cyclin D1 during cell cycle progression without altering levels of the cyclin-dependent kinase cdk4 or cyclin E and its associated kinase, cdk2. Exposure of cells to PTHRP or cAMP resulted in a reduction in retinoblastoma gene product (Rb) phosphorylation. Immunoblotting of extracts from cAMP-treated cells with antibodies to cdk inhibitors revealed a striking increase in p27(kip1) abundance coincident with the G1 block. Immunoprecipitation with an anti-cyclin D1 antibody of cell lysates prepared from cAMP-treated cells followed by immunoblotting with antisera to p27(kip1) disclosed a threefold increase in p27(kip1) associated with cyclin D1 compared with lysates treated with serum alone. We conclude that PTHRP, by increasing intracellular cAMP, induces VSMC cycle arrest in mid-G1. This occurs secondary to a suppression in cyclin D1 and induction of p27(kip1) expression, which in turn inhibits Rb phosphorylation.
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Affiliation(s)
- W D Stuart
- Departments of Medicine and Molecular and Cellular Physiology, University of Cincinnati, Cincinnati, Ohio 45267, USA
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19
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Lang H, Endlich N, Lindner V, Endlich K, Massfelder T, Stewart AF, Saussine C, Helwig JJ. Parathyroid hormone-related protein in rat penis: expression, localization, and effect on cavernosal pressure. Endocrinology 1999; 140:4342-50. [PMID: 10465308 DOI: 10.1210/endo.140.9.7005] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Although PTH-related protein-(1-36) [PTHrP-(1-36)] is known to be expressed in smooth muscle and to exert potent myorelaxant effects, its tonic effects on cavernosal smooth muscle has not yet been explored. Using the RT-PCR technique, the present study establishes that PTHrP messenger RNA is present in microdissected corpus cavernosa in the rat. In immunohistochemical studies using affinity-purified antibodies to middle regions of PTHrP, immunostaining was localized throughout the penile structures, including vessels, cavernosal smooth muscle, and trabecular fibroblasts. Strong immunostaining for PTHrP was also detected in the dorsal nerve bundles. In anesthetized rats, intracavernosally injected boluses of increasing doses of PTHrP-(1-36) (0.3-30 pmol in 100 microl saline) had little effect on intracavernosal pressure. However, they markedly potentiated the dilatory response to papaverine (8-800 nmol), increasing the papaverine-induced intracavernous pressure by 2.5-fold, close to the mean arterial pressure. In conclusion, the cavernosal expression of PTHrP messenger RNA, the distribution of immunoreactive PTHrP throughout the structuro-functional components of the erectile apparatus and its strong potentiating action on papaverine-induced cavernosal relaxation, collectively suggest that PTHrP participates in the control of cavernosal tone.
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Affiliation(s)
- H Lang
- Renovascular Physiology and Pharmacology, (CJF INSERM 9409-EA MENRT 2307), Louis Pasteur University Medical School, Strasbourg, France
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20
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Maeda S, Sutliff RL, Qian J, Lorenz JN, Wang J, Tang H, Nakayama T, Weber C, Witte D, Strauch AR, Paul RJ, Fagin JA, Clemens TL. Targeted overexpression of parathyroid hormone-related protein (PTHrP) to vascular smooth muscle in transgenic mice lowers blood pressure and alters vascular contractility. Endocrinology 1999; 140:1815-25. [PMID: 10098520 DOI: 10.1210/endo.140.4.6646] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
PTH-related protein (PTHrP) and its receptor are expressed in vascular smooth muscle cells and are believed to participate in the local regulation of vascular tone. To explore the function of locally produced PTHrP in vascular smooth muscle in vivo, we developed transgenic mice that overexpress PTHrP in smooth muscle using a smooth muscle alpha-actin promoter to direct expression of the transgene. In the PTHrP-overexpressing mice, messenger RNA expression was mainly restricted to smooth muscle-containing tissues. Several founders also expressed the transgene in bone and heart and exhibited striking abnormalities in the development of these tissues. In PTHrP-overexpressing mice, blood pressure was significantly lower than that in wild-type controls (121 +/- 3 vs. 135 +/- 2 mm Hg; P < 0.01). Moreover, the magnitude of the vasorelaxant response to iv infusions of PTHrP-(1-34)NH2 was significantly attenuated in the transgenic animals. A similar desensitization to PTHrP was observed in aortic ring and portal vein preparations. Surprisingly, PTHrP-overexpressing mice were also significantly less responsive to the hypotensive action of infused acetylcholine in vivo and to the relaxant actions of acetylcholine on aortic vessel preparations in vitro. In summary, we have successfully targeted overexpression of PTHrP to the smooth muscle of transgenic mice. When expressed in its normal autocrine/paracrine setting, PTHrP lowers systemic blood pressure and decreases vascular responsiveness to further relaxation by PTHrP and other endothelium-dependent vasorelaxants such as acetylcholine. We postulate that the heterologous desensitization to acetylcholine-induced relaxation in PTHrP-overexpressing blood vessels involves desensitization of second messenger/effector signaling pathways common to PTHrP and acetylcholine.
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Affiliation(s)
- S Maeda
- Department of Medicine, University of Cincinnati, Ohio 45267-0547, USA
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21
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Steers WD, Broder SR, Persson K, Bruns DE, Ferguson JE, Bruns ME, Tuttle JB. Mechanical stretch increases secretion of parathyroid hormone-related protein by cultured bladder smooth muscle cells. J Urol 1998; 160:908-12. [PMID: 9720586 DOI: 10.1097/00005392-199809010-00087] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Parathyroid hormone-related protein (PTHrP) immunoreactivity has been detected in the bladder and increases in response to dilatation secondary to obstruction. The hypothesis that PTHrP could be increased solely by stretch rather than other possible in vivo variables was tested by stretching cultured bladder smooth muscle cells and analyzing the culture medium for this protein. In response to mechanical stretch, PTHrP was increased in smooth muscle cell cultures. Immunoradiometric assay revealed maximal rates of secretion for the first eight hours. Comparison of percent change in PTHrP secretion of flexed cells for the various flex parameters revealed a difference (p = .006) when the degree of stretch (i.e. percent elongation) was altered. The protein synthesis inhibitor cycloheximide inhibited basal and stretch-induced PTHrP secretion. PTHrP (1-100 nM) relaxed carbachol-contracted bladder body and base by 15% and 45% respectively. PTHrP did not affect bladder contractions induced by potassium (124 mM) or alpha-beta MeATP (10 microM). Increased PTHrP secretion in response to stretch of smooth muscle raises the possibility of an autocrine action to relax the bladder during filling. PTHrP may also exert a paracrine action on vessels regulating blood flow during bladder filling or it may modulate neural activity.
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Affiliation(s)
- W D Steers
- Department of Urology, University of Virginia School of Medicine, Charlottesville, USA
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22
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Torday JS, Sanchez-Esteban J, Rubin L. Paracrine Mediators of Mechanotransduction in Lung Development. Am J Med Sci 1998. [DOI: 10.1016/s0002-9629(15)40403-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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23
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Affiliation(s)
- T A Guise
- Department of Medicine, University of Texas Health Science Center at San Antonio 78284-7877, USA.
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24
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Massfelder T, Fiaschi-Taesch N, Stewart AF, Helwig JJ. Parathyroid hormone-related peptide--a smooth muscle tone and proliferation regulatory protein. Curr Opin Nephrol Hypertens 1998; 7:27-32. [PMID: 9442359 DOI: 10.1097/00041552-199801000-00005] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Parathyroid hormone-related protein (PTHrP) appears to play crucial roles in the cardiovascular system. Over the past few years it has become apparent that there is more than one receptor recognizing parathyroid hormone or PTHrP, or both, and that PTHrP is not only a potent vasodilator of vascular smooth muscle cell tone, but is also a regulator of vascular smooth muscle cell proliferation and a secretagogue of renin and vasopressin. Investigators in several laboratories have started to query whether PTHrP intervenes in vascular diseases such as hypertension, (re)stenosis-atherosclerosis and endotoxaemia.
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Affiliation(s)
- T Massfelder
- Pharmacology Department, University Louis Pasteur School of Medicine, Strasbourg, France
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25
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Yamamoto S, Morimoto I, Zeki K, Ueta Y, Yamashita H, Kannan H, Eto S. Centrally administered parathyroid hormone (PTH)-related protein(1-34) but not PTH(1-34) stimulates arginine-vasopressin secretion and its messenger ribonucleic acid expression in supraoptic nucleus of the conscious rats. Endocrinology 1998; 139:383-8. [PMID: 9421437 DOI: 10.1210/endo.139.1.5697] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
It has been suggested that PTH-related protein (PTHrP) is an endogenous modulator of cardiovascular systems. We have reported that PTHrP(1-34), but not PTH(1-34), causes the release of arginine-vasopressin (AVP) from the supraoptic nucleus (SON) of the hypothalamus in vitro through a novel receptor distinct from the PTH/PTHrP receptors (type I or type II) described previously. In this study, we have investigated the in vivo effects of PTHrP(1-34) on AVP secretion and its, messenger RNA (mRNA) expression in the SON in conscious rats. Intracerebroventricular (i.c.v.) administration of PTHrP(1-34) resulted in an increase in plasma AVP concentration in a dose-dependent manner (0-400 pmol/rat). The maximal effect was obtained at 15 min after i.c.v. administration of PTHrP(1-34). Neither PTHrP(7-34) nor PTH(1-34) had any effect on plasma AVP levels. PTHrP(1-34)-induced AVP secretion was antagonized by pretreatment with PTHrP(7-34) but not by that with PTH(1-34). In addition, in situ hybridization study revealed that AVP mRNA expression in the SON and paraventricular nucleus was significantly increased 30 min after i.c.v. administration of PTHrP(1-34) and reached a maximum at 180 min. Furthermore, in Northern blot analyses, AVP mRNA expression in the SON was increased to approximately a 2-fold of basal level by PTHrP(1-34). On the other hand, neither PTHrP(7-34) or PTH(1-34) had any effect on the mRNA expression. The PTHrP(1-34)-stimulated AVP mRNA expression was eliminated by pretreatment with PTHrP(7-34) but not with PTH(1-34). These results suggest that, in the central nervous system, PTHrP(1-34) is involved in AVP secretion through a novel receptor distinct from the PTH/PTHrP receptors reported previously, playing a role in the body water and electrolyte homeostasis.
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Affiliation(s)
- S Yamamoto
- First Department of Internal Medicine, School of Medicine, University of Occupational and Environmental Health, Kitakyushu, Japan
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26
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Abstract
Cardiovascular cells (cardiomyocytes and smooth muscle cells) are target cells for parathyroid hormone (PTH) and the structurally related peptide parathyroid hormone-related peptide (PTH-rP). PTH activates protein kinase C (PKC) of cardiomyocytes via a PKC activating domain previously identified on chondrocytes. Activation of PKC leads to hypertrophic growth and re-expression of fetal type proteins in cardiomyocytes. This hypertrophic effect of PTH might contribute to left ventricular hypertrophy in hemodialysis patients with secondary hyperparathyroidism. PTH-rP is expressed in cardiovascular cells (endothelial cells and smooth muscle cells). It does not mimic the above described actions of PTH but exerts effects of its own on cardiomyocytes. These effects involve activation of protein kinase A, via a N-terminal domain distinct from that identified on PTH, and activation of PKC, via a C-terminally located domain distinct from that found on PTH. On smooth muscle cells PTH and PTH-rP reduce the influence of extracellular calcium, through cAMP-dependent mechanisms. These inhibitory effects on voltage-dependent L-type calcium channels of smooth muscle cells cause vasorelaxation. Present studies concerning cardiovascular actions of either PTH and PTH-rP suggest that increased plasma levels of PTH and PTH-rP influence cardiomyocyte and smooth muscle cell physiology. It can be assumed that PTH-rP acts as a paracrine or autocrine modulator in heart and vessels.
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Affiliation(s)
- K D Schlüter
- Physiologisches Institut, Justus-Liebig-Universität Giessen, Germany
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27
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Noda M, Katoh T, Kurokawa K, Takuwa Y. Increased expression of parathyroid hormone-related peptide gene in blood vessels of spontaneously hypertensive rats. Hypertension 1997; 30:1284-8. [PMID: 9369289 DOI: 10.1161/01.hyp.30.5.1284] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
We have shown recently that mechanical stretch of cultured rat aortic smooth muscle cells induces a marked increase in gene expression of the vasorelaxant parathyroid hormone-related peptide. In the present study, we investigated whether mechanical force affected the in vivo parathyroid hormone-related peptide gene expression in blood vessels. Northern blot analysis revealed that stretch of isolated rat aortic strips increased the expression level of parathyroid hormone-related peptide mRNA. The parathyroid hormone-related peptide transcript level in aorta and mesenteric vessels from 18-week-old spontaneously hypertensive rats (SHR) was 2.5- and 2.2-fold higher, respectively, compared with age-matched Wistar-Kyoto (WKY) controls, whereas the parathyroid hormone-related peptide mRNA level in aorta from normotensive 4-week-old SHR was similar to that of age-matched WKY controls. The aortic parathyroid hormone-related peptide content was higher in 18-week-old SHR than in age-matched WKY controls. Moreover, treatment of mature SHR with an angiotensin II type 1 receptor antagonist or hydralazine caused a concomitant decrease in the parathyroid hormone-related peptide transcript level in aorta with lowering of blood pressure. These results suggest that the in vivo parathyroid hormone-related peptide gene expression in blood vessels is under the control of mechanical force, pointing to a role of parathyroid hormone-related peptide in the regulation of vascular tone.
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Affiliation(s)
- M Noda
- Department of Cardiovascular Biology, Faculty of Medicine, University of Tokyo, Japan
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Shane E, Mancini D, Aaronson K, Silverberg SJ, Seibel MJ, Addesso V, McMahon DJ. Bone mass, vitamin D deficiency, and hyperparathyroidism in congestive heart failure. Am J Med 1997; 103:197-207. [PMID: 9316552 DOI: 10.1016/s0002-9343(97)00142-3] [Citation(s) in RCA: 268] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
PURPOSE In contrast to renal and hepatic failure, congestive heart failure (CHF) has not been associated with a defined metabolic bone disorder. However, low bone mass has been reported in patients with CHF who receive a cardiac transplant. Both the pathophysiology and therapy of CHF may influence bone and mineral homeostasis and evidence that calciotropic hormones may affect cardiovascular function is accumulating. Therefore, we evaluated patients with severe CHF to determine the prevalence of osteoporosis and to characterize relationships between mineral homeostasis, bone turnover, bone mass, and severity of CHF. PATIENTS AND METHODS One hundred one patients (79 men and 22 women, aged 25 to 70 years) with severe CHF (New York Heart Association functional class III or IV) referred for consideration for cardiac transplantation were evaluated with measurements of serum 25-hydroxyvitamin D (25-OHD), 1,25 dihydroxyvitamin D [1,25(OH)2D], intact parathyroid hormone (PTH), markers of bone turnover (serum osteocalcin, urinary hydroxyproline, and pyridinium crosslinks); bone mineral density (BMD) by dual energy x-ray absorptiometry was measured in 91 patients. Left ventricular ejection fraction (LVEF) and resting cardiac output (CO) were determined in 88 and maximal treadmill exercise testing and peak oxygen consumption were performed in 45 patients. RESULTS Osteoporosis (T score < or = -2.5) was present in 7% at the lumbar spine, 6% at the total hip, and 19% at the femoral neck. Osteopenia (T scores between -1.0 and -2.5) was present in 43% at the lumbar spine, 47% at the total hip, and 42% at the femoral neck. Women were more severely affected (P = 0.007). Frankly low serum 25-OHD (< or = 9 pg/mL) and 1,25(OH)2D (< or = 15 pg/mL) levels were found in 17% and 26% of the patients, respectively, and elevated serum PTH (> or = 65 pg/mL) in 30%. Both low serum 1,25(OH)2D and increased serum PTH were associated with prerenal azotemia. Low serum vitamin D metabolites were associated with biochemical evidence of increased bone turnover, but BMD did not differ by vitamin D or PTH status. Patients with more severe CHF had significantly lower vitamin D metabolites and higher bone turnover, whereas elevated PTH was associated with better LVEF (21 +/- 1 versus 18 +/- 1%; P = 0.05) and correlated positively with resting CO (R = 0.220; P = 0.04). CONCLUSIONS Osteopenia or osteoporosis were observed in approximately half of these patients with severe CHF. Abnormal calciotropic hormone concentrations, also common, were associated with evidence of increased bone resorption but were not related to BMD in this cross-sectional study. Abnormal concentrations of calciotropic hormones were related to the severity of cardiovascular compromise. Because both low BMD and low serum concentrations of 25-OHD in patients with CHF are associated with higher rates of bone loss and fracture after cardiac transplantation, patients should be evaluated for and receive appropriate therapy for these disorders.
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Affiliation(s)
- E Shane
- Department of Medicine, College of Physicians and Surgeons, Columbia University, New York, New York 10032, USA
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29
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Affiliation(s)
- G R Mundy
- Department of Medicine/Endocrinology, University of Texas Health Science Center, San Antonio 78284-7877, USA
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30
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Massfelder T, Parekh N, Endlich K, Saussine C, Steinhausen M, Helwig JJ. Effect of intrarenally infused parathyroid hormone-related protein on renal blood flow and glomerular filtration rate in the anaesthetized rat. Br J Pharmacol 1996; 118:1995-2000. [PMID: 8864534 PMCID: PMC1909869 DOI: 10.1111/j.1476-5381.1996.tb15635.x] [Citation(s) in RCA: 52] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
1. Parathyroid hormone-related protein (PTHrP) is expressed in the kidney and acts on vascular PTH/ PTHrP receptors to vasodilate the isolated kidney and to stimulate renin release. However, effects of PTHrP on renal blood flow (RBF) and glomerular filtration rate (GFR) in vivo have not been assessed in the absence of its cardiac, peripheral and central effects. We investigated the renal effects of PTH and PTHrP infused into the left renal artery of anaesthetized rats. 2. Intrarenal infusions, adjusted to generate increasing concentrations of human PTHrP(1-34) and rat PTH(1-34) in renal plasma (2 x 10(-11) to 6 x 10(-9) M) produced a comparable dose-dependent increase in RBF. The rise was 4% at the lowest and 34% at the highest concentrations of peptides. Up to a concentration of 2 x 10(-9) M, mean arterial pressure (MAP) and heart rate were not affected, but at 6 x 10(-9) M, intrarenally infused peptides reached the peripheral circulation, and caused a fall in MAP within a few minutes. While MAP returned to basal value after the last peptide infusion, RBF remained more than 10% above control for at least 30 min. 3. Two competitive PTH/PTHrP receptor antagonists, [Nle8,18, Tyr34]-bPTH(3-34)amide and [Leu11, D-Trp12]-hPTHrP(7-34)amide (2 x 10(-8) M) were devoid of agonist activity, but markedly antagonized the dose-dependent increase in RBF elicited by PTHrP. 4. GFR and urine flow were measured in left PTHrP-infused experimental kidney and right control kidney. Renal PTHrP concentration of 10(-10) M elevated left RBF by 10%, and GFR by 20% without significantly increasing filtration fraction, and increased urine flow by 57%. In the right control kidney GFR and diuresis did not change. 5. The results indicate that PTHrP has similar renal haemodynamic effects as PTH and increases RBF, GFR and diuresis in anaesthetized rats.
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Affiliation(s)
- T Massfelder
- Laboratoire de Physiologie Cellulaire Rénale, Faculté de Médecine, Université Louis Pasteur, CJF INSERM 9409, Strasbourg, France
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Ozeki S, Ohtsuru A, Seto S, Takeshita S, Yano H, Nakayama T, Ito M, Yokota T, Nobuyoshi M, Segre GV, Yamashita S, Yano K. Evidence that implicates the parathyroid hormone-related peptide in vascular stenosis. Increased gene expression in the intima of injured carotid arteries and human restenotic coronary lesions. Arterioscler Thromb Vasc Biol 1996; 16:565-75. [PMID: 8624779 DOI: 10.1161/01.atv.16.4.565] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Proliferation of vascular smooth muscle cells (VSMCs) is considered to be one key event underlying the pathophysiology of restenosis after angioplasty. The parathyroid hormone-related peptide (PTHrP) and its receptor, a local autocrine and paracrine regulator of cellular growth in a variety of normal cell types, have been reported in the vicinity of VSMCs. To investigate how PTHrP might be involved in the process of neointimal formation after balloon angioplasty, we examined PTHrP expression in balloon-denuded rat carotid arteries and human coronary arteries that had been retrieved by directional atherectomy. In rat carotid arteries, the RNase protection assay and in situ hybridization demonstrated that PTHrP mRNA expression increased fourfold to sixfold 1 to 7 days after denudation and continued for 28 days, coincident with downregulation of PTH/PTHrP receptor mRNA expression. In situ hybridization and immunohistochemistry revealed that PTHrP expression in balloon-denuded carotid arteries was mainly localized to the neointima. To confirm the involvement of the PTHrP in human coronary artery restenotic lesions, immunohistochemical analysis of human coronary atherectomy specimens (23 primary and 10 restenotic lesions) was then performed. The number of intimal cells that expressed PTHrP protein was significantly higher in restenotic (407 +/- 53 cells/mm2; range, 143 to 739) than in stable angina (50 +/- 12 cells/mm2; range, 18 to 132; P<.05) or unstable angina (129 +/- 16 cells/mm2; range, 21 to 232; P<.05) specimens. These data demonstrate that PTHrP gene expression in VSMCs markedly increases during neointimal formation, supporting the hypothesis that PTHrP may play an important role in vascular stenosis as a regulator of VSMC proliferation.
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Affiliation(s)
- S Ozeki
- Third Department of Internal Medicine, Atomic Disease Institute, Nagasaki University School of Medicine, Japan
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Hultgårdh-Nilsson A, Cercek B, Wang JW, Naito S, Lövdahl C, Sharifi B, Forrester JS, Fagin JA. Regulated expression of the ets-1 transcription factor in vascular smooth muscle cells in vivo and in vitro. Circ Res 1996; 78:589-95. [PMID: 8635216 DOI: 10.1161/01.res.78.4.589] [Citation(s) in RCA: 64] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Ets-1 regulates the transcription of several genes encoding extracellular matrix proteins (ie, osteopontin and tenascin) as well as enzymes involved in degradation and remodeling of the extracellular matrix (ie, stromelysin and urokinase plasminogen activator). In the present study, we investigated the regulation of c-ets-1 in cultured rat vascular smooth muscle cells as well as in the arterial wall after balloon injury in vivo. Serum-starved smooth muscle cells exposed to serum for various time points express a major c-ets-1 mRNA transcript of 5.3 kb and minor bands of 4.0 and 2.5 kb with a peak at 2 hours after stimulation. These effects were concentration dependent. Western blotting revealed an increase in 55- and 40-kD immunoreactive ets-1 proteins in cells treated with serum for 2 hours, and binding to an oligonucleotide containing the ets-1 consensus cis-acting motif was demonstrated by electrophoretic mobility shift assay. Ets-1 mRNA abundance was induced with a peak at 2 hours after stimulation with platelet-derived growth factor-BB and with angiotensin II. There was a distinct increase of ets-1 immunoreactivity in the inner layer of the media 2 hours after balloon catheter injury of rat arteries, which declined after 6 hours and returned to the basal level 1 day after vessel wall damage. Arterial c-ets-1 mRNA content was induced with an identical time course. These findings suggest that c-ets-1 may be of importance in the mitogenic signaling pathway of smooth muscle cells grown in culture. In addition, ets-1 may play a role in the activation of smooth muscle cells in vivo after mechanical injury of the vessel wall. Because the ets-1 transcription factor activates the gene expression of a number of mRNA species involved in matrix deposition and degradation, these data are compatible with a role for ets-1 in vascular remodeling and/or cell migration.
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Affiliation(s)
- A Hultgårdh-Nilsson
- Division of Cardiology, Cedars-Sinai Medical Center, UCLA Medical School, Los Angeles, Calif, USA
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Bruns ME, Ferguson JE, Bruns DE, Burton DW, Brandt DW, Jüppner H, Segre GV, Deftos LJ. Expression of parathyroid hormone-related peptide and its receptor messenger ribonucleic acid in human amnion and chorion-decidua: implications for secretion and function. Am J Obstet Gynecol 1995; 173:739-46. [PMID: 7573236 DOI: 10.1016/0002-9378(95)90333-x] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
OBJECTIVE Our purpose was to define the location and packaging of parathyroid hormone-related peptide in amnion-chorion and the potential target tissues for its action in fetal membranes. STUDY DESIGN We studied fetal membranes by use of light microscopic immunocytochemistry with three monoclonal antibodies against distinct regions of the parathyroid hormone-related peptide molecule. For electron microscopy immunogold analysis with a monoclonal antibody specific to the 109-141 fragment was used to observe parathyroid hormone-related peptide intracellularly in amnion membrane and in the chorion layers. Multiplex reverse transcriptase-polymerase chain reaction with Southern blotting was used to identify parathyroid hormone/parathyroid hormone-related peptide receptor and control messenger ribonucleic acids in amnion and chorion-decidua. RESULTS All monoclonal antibodies revealed immunoreactive parathyroid hormone-related peptide in the amniotic epithelial cells and in some fibroblast-like cells embedded in the extracellular matrix of the amnion. Parathyroid hormone-related peptide was also found in the chorion in fibroblast and trophoblast layers and in decidua. Ultrastructurally immunogold particles were evenly distributed throughout the amniotic epithelial cells and were present in apical microvilli and near the basal membranes. Electron microscopy studies of the chorion cytotrophoblast also showed freely dispersed immunogold particles of parathyroid hormone-related peptide with no packaging in secretory granules. Low to undetectable levels of parathyroid hormone/parathyroid hormone-related peptide receptor messenger ribonucleic acid were found in amnion tissue, whereas abundant receptor messenger ribonucleic acid was found in chorion-decidua. CONCLUSIONS These results suggest the presence of a parathyroid hormone-related peptide paracrine system within the human fetal membranes.
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Affiliation(s)
- M E Bruns
- Department of Pathology, University of Virginia, Charlottesville, USA
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