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. 2007 May 1;10(2):519–528. doi: 10.1111/j.1582-4934.2006.tb00417.x

Caveolar nanospaces in smooth muscle cells

Mihaela Gherghiceanu a, L M Popescu a,b,*
PMCID: PMC3933139  PMID: 16796817

Abstract

Caveolae, specialized membrane nanodomains, have a key role in signaling processes, including calcium handling in smooth muscle cells (SMC). We explored the three-dimensional (3D) architecture of peripheral cytoplasmic space at the nanoscale level and the close spatial relationships between caveolae, sarcoplasmic reticulum (SR), and mitochondria, as ultrastructural basis for an excitation-contraction coupling system and, eventually, for excitation - transcription coupling. About 150 electron micrographs of SMC showed that superficial SR and peripheral mitochondria are rigorously located along the caveolar domains of plasma membrane, alternating with plasmalemmal dense plaques. Electron micrographs made on serial ultrathin sections were digitized, then computer-assisted organellar profiles were traced on images, and automatic 3D reconstruction was obtained using the ‘Reconstruct’ software. The reconstruction was made for 1 μm3 in rat stomach (muscularis mucosae) and 10 μm3 in rat urinary bladder (detrusor smooth muscle). The close appositions (about 15 nm distance) of caveolae, peripheral SR, and mitochondria create coherent cytoplasmic nanoscale subdomains. Apparently, 80% of caveolae establish close contacts with SR and about 10% establish close contacts with mitochondria in both types of SMC. Thus, our results show that caveolae and peripheral SR build Ca2+release units in which mitochondria often could play a part. The caveolae-SR couplings occupy 4.19% of the cellular volume in stomach and 3.10% in rat urinary bladder, while caveolae-mitochondria couplings occupy 3.66% and 3.17%, respectively. We conclude that there are strategic caveolae-SR or caveolae-mitochondria contacts at the nanoscale level in the cortical cytoplasm of SMC, presumably responsible for a vectorial control of free Ca2+ cytoplasmic concentrations in definite nanospaces. This may account for slective activation of specific Ca2+ signaling pathways.

Keywords: caveolae, sarcoplasmic reticulum, mitochondria, nanospace, nanomedicine, Ca2+ release unit, Ca2+ homeostasis, 3D reconstruction, excitation-contraction coupling, electron microscopy

References

  • 1.Palade GE. Fine structure of blood capillaries. J Appl Phys. 1953;24:1424–36. [Google Scholar]
  • 2.Bruns RR, Palade GE. Studies on blood capillaries. II. Transport on ferritin molecules across the wall of muscle capillaries. J Cell Biol. 1968;37:277–99. doi: 10.1083/jcb.37.2.277. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 3.Gabella G. Caveolae intracellulares and sarcoplasmic reticulum in smooth muscle. J Cell Sci. 1971;8:601–9. doi: 10.1242/jcs.8.3.601. [DOI] [PubMed] [Google Scholar]
  • 4.Popescu LM, Diculescu I, Zelck U, Ionescu N. Ulrastructural distribution of calcium in smooth-muscle cells of guinea-pig taenia coli - correlated electron-microscopic and quantitative study. Cell Tiss Res. 1974;154:357–78. doi: 10.1007/BF00223732. [DOI] [PubMed] [Google Scholar]
  • 5.Popescu LM. Conceptual model of the excitation-contraction coupling in smooth muscle; the possible role of the surface microvesicles. Studia Biophysica (Berlin) 1974;44:S141–53. [Google Scholar]
  • 6.Popescu LM, Diculescu I. Calcium in smooth muscle sarcoplasmic reticulum in situ Conventional and X-ray analytical electron microscopy. J Cell Biol. 1975;67:911–8. doi: 10.1083/jcb.67.3.911. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 7.Anderson RGW. The caveolae membrane system. Ann Rev Biochem. 1998;67:199–225. doi: 10.1146/annurev.biochem.67.1.199. [DOI] [PubMed] [Google Scholar]
  • 8.Fujimoto T. Cell biology of caveolae and its implication for clinical medicine. Nagoya J Med Sci. 2000;63:9–18. [PubMed] [Google Scholar]
  • 9.Taggart MJ. Smooth muscle excitation-contraction coupling: a role for caveolae and caveolins. News Physiol Sci. 2001;16:61–5. doi: 10.1152/physiologyonline.2001.16.2.61. [DOI] [PubMed] [Google Scholar]
  • 10.Shin JS, Abraham SN. Caveolae - not just craters in the cellular landscape. Science. 2001;293:1447–8. doi: 10.1126/science.1061079. [DOI] [PubMed] [Google Scholar]
  • 11.Parton RG. Life without caveolae. Science. 2001;293:2404–5. doi: 10.1126/science.1065677. [DOI] [PubMed] [Google Scholar]
  • 12.Stan RV. Structure and function of endothelial caveolae. Microsc Res Tech. 2002;57:350–64. doi: 10.1002/jemt.10089. [DOI] [PubMed] [Google Scholar]
  • 13.Razani B, Woodman SE, Lisanti MP. Caveolae: from cell biology to animal physiology. Pharmacol Rev. 2002;54:431–67. doi: 10.1124/pr.54.3.431. [DOI] [PubMed] [Google Scholar]
  • 14.Parton RG. Caveolae - from ultrastructure to molecular mechanisms. Nat Rev Mol Cell Biol. 2003;4:162–7. doi: 10.1038/nrm1017. [DOI] [PubMed] [Google Scholar]
  • 15.Bergdahl A, Sward K. Caveolae-associated signaling in smooth muscle. Can J Physiol Pharmacol. 2004;82:289–99. doi: 10.1139/y04-033. [DOI] [PubMed] [Google Scholar]
  • 16.White MA, Anderson RGW. Signaling networks in living cells. Ann Rev Pharmacol Toxicol. 2005;45:587–603. doi: 10.1146/annurev.pharmtox.45.120403.095807. [DOI] [PubMed] [Google Scholar]
  • 17.Stan RV. Structure of caveolae. Biochim Biophys Acta. 2005;1746:334–48. doi: 10.1016/j.bbamcr.2005.08.008. [DOI] [PubMed] [Google Scholar]
  • 18.Bolton TB. Calcium events in smooth muscles and their interstitial cells; physiological roles of sparks. J Physiol. 2006;570:5–11. doi: 10.1113/jphysiol.2005.095604. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 19.Daniel EE, EI-Yazbi A, Cho WJ. Caveolae and calcium handling, a review and a hypothesis. J Cell Mol Med. 2006;10:529–44. doi: 10.1111/j.1582-4934.2006.tb00418.x. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 20.Schroeder F, Gallegos AM, Atshaves BP, Storey SM, McIntosh AL, Petrescu AD, Huang H, Starodub O, Chao H, Yang H, Frolov A, Kier AB. Recent advances in membrane microdomains: rafts, caveolae, and intracellular cholesterol trafficking. Exp Biol Med. 2001;226:873–90. doi: 10.1177/153537020122601002. [DOI] [PubMed] [Google Scholar]
  • 21.van Meer G. The different hues of lipid rafts. Science. 2002;296:855–6. doi: 10.1126/science.1071491. [DOI] [PubMed] [Google Scholar]
  • 22.Fielding CJ, Fielding PE. Relationship between cholesterol trafficking and signaling in rafts and caveolae. Biochim Biophys Acta. 2003;1610:219–28. doi: 10.1016/s0005-2736(03)00020-8. [DOI] [PubMed] [Google Scholar]
  • 23.Martin S. Parton R. Caveolin, cholesterol, and lipid bodies. Sem Cell Dev Biol. 2005;16:163–74. doi: 10.1016/j.semcdb.2005.01.007. [DOI] [PubMed] [Google Scholar]
  • 24.Parton RG, Hanzal-Bayer M, Hancock JF. Biogenesis of caveolae: a structural model for caveolin-induced domain formation. J Cell Sci. 2006;119:787–96. doi: 10.1242/jcs.02853. [DOI] [PubMed] [Google Scholar]
  • 25.Darby PJ, Kwan CY, Daniel EE. Caveolae from canine airway smooth muscle contain the necessary components for a role in Ca2+ handling. Am J Physiol Lung Cell Mol Physiol. 2000;279:L1226–35. doi: 10.1152/ajplung.2000.279.6.L1226. [DOI] [PubMed] [Google Scholar]
  • 26.Je HD, Gallant C, Leavis PC, Morgan KG. Caveolin-1 regulates contractility in differentiated vascular smooth muscle. Am J Physiol Heart Circ Physiol. 2004;286:H91–8. doi: 10.1152/ajpheart.00472.2003. [DOI] [PubMed] [Google Scholar]
  • 27.Vinten J, Johnsen AH, Roepstroff P, Harpoth J, Tranum-Jensen J. Identification of a major protein on the cytosolic face of caveolae. Biochim Biophys Acta. 2005;1717:34–40. doi: 10.1016/j.bbamem.2005.09.013. [DOI] [PubMed] [Google Scholar]
  • 28.Spisni E, Tomasi V, Cestaro A, Tosatto SC. Structural insights into the function of human caveolin 1. Biochem Biophys Res Commun. 2005;338:1383–90. doi: 10.1016/j.bbrc.2005.10.099. [DOI] [PubMed] [Google Scholar]
  • 29.Yao Q, Chen J, Cao H, Orth JD, McCaffery JM, Stan RV, McNiven MA. Caveolin-1 interacts directly with dynamin-2. J Mol Biol. 2005;348:491–501. doi: 10.1016/j.jmb.2005.02.003. [DOI] [PubMed] [Google Scholar]
  • 30.Riley M, Baker PN, Tribe RM, Taggart MJ. Expression of scaffolding, signalling and contractile-filament proteins in human myometria: effects of pregnancy and labour. J Cell Mol Med. 2005;9:122–34. doi: 10.1111/j.1582-4934.2005.tb00342.x. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 31.Yu J, Bergaya S, Murata T, Alp IF, Bauer MP, Lin MI, Drab M, Kurzchalia TV, Stan RV, Sessa WC. Direct evidence for the role of caveolin-1 and caveolae in mechanotransduction and remodeling of blood vessels. J Clin Invest. 2006;116:1222–5. doi: 10.1172/JCI27100. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 32.Pelkmans L, Fava E, Grabner H, Habermann B, Krausz E, Zerial M. Genome-wide analysis of human kinase in clathrin- and caveolae/raft-mediated endocytosis. Nature. 2005;436:78–86. doi: 10.1038/nature03571. [DOI] [PubMed] [Google Scholar]
  • 33.McMahon KA, Zhu M, Know SW, Liu P, Zhao Y, Anderson GW. Detergent-free caveolae proteome suggests an interaction with ER and mitocondria. Proteomics. 2006;6:143–52. doi: 10.1002/pmic.200500208. [DOI] [PubMed] [Google Scholar]
  • 34.Grilo A, Fernandez ML, Beltran M, Ramirez-Lorca R, Gonzalez MA, Royo JL, Gutierrez-Tous R, Moron FJ, Couto C, Serrano-Rios M, Saez ME, Ruiz A, Real LM. Genetic analysis of CAV1 gene in hypertension and metabolic syndrome. Thromb Haemost. 2006;95:696–701. [PubMed] [Google Scholar]
  • 35.Simionescu N, Simionescu M, Palade GE. Permeability of muscle capillaries to small heme-peptides. Evidence for the existence of patent transedothelial channels. J Cell Biol. 1975;64:586–607. doi: 10.1083/jcb.64.3.586. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 36.Predescu SA, Predescu DN, Palade GE. Endothelial transcytotic machinery involves supramolecular protein-lipid complexes. Mol Biol Cell. 2001;12:1019–33. doi: 10.1091/mbc.12.4.1019. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 37.Anderson RG, Kamen BA, Rothberg KG, Lacey SW. Potocytosis: sequestration and transport of small molecules by caveolae. Science. 1992;255:410–1. doi: 10.1126/science.1310359. [DOI] [PubMed] [Google Scholar]
  • 38.Anderson RG. Potocytosis of small molecules and ions by caveolae. Trends Cell Biol. 1993;3:69–72. doi: 10.1016/0962-8924(93)90065-9. [DOI] [PubMed] [Google Scholar]
  • 39.Anderson HA, Chen Y, Norkin LC. Bound simian virus 40 translocates to caveolin enriched membrane domains, and its entry is inhibited by drugs and selectively disrupt caveolae. Mol Biol Cell. 1996;7:18–25. doi: 10.1091/mbc.7.11.1825. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 40.Stang E, Kartenbeck J, Parton RG. Major histocompatibility complex class I molecules mediate association of SV40 with caveolae. Mol Biol Cell. 1997;8:47–57. doi: 10.1091/mbc.8.1.47. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 41.Pelkmans L, Kartenbeck J, Helenius A. Caveolar endocytosis of simian virus 40 reveals a new two-step vesicular-transport pathway to the ER. Nature Cell Biol. 2001;3:473–83. doi: 10.1038/35074539. [DOI] [PubMed] [Google Scholar]
  • 42.Ostrom RS, Insel PA. Caveolar microdomains of the sarcolemma: compartmentation of signaling molecules comes of age. Circ Res. 1999;84:1110–2. doi: 10.1161/01.res.84.9.1110. [DOI] [PubMed] [Google Scholar]
  • 43.Isshiki M, Anderson RGW. Function of caveolae in Ca2+ entry and Ca2+-dependent signal transduction. Traffic. 2003;4:717–23. doi: 10.1034/j.1600-0854.2003.00130.x. [DOI] [PubMed] [Google Scholar]
  • 44.Poburko D, Kuo KH, Dai J, Lee CH, Van Breemen C. Organellar junctions promote targeted Ca2+ signaling in smooth muscle: why two membranes are better than one. Trends in Pharmacological Sciences. 2004;25:8–15. doi: 10.1016/j.tips.2003.10.011. [DOI] [PubMed] [Google Scholar]
  • 45.Rizzuto R, Pozzan T. Microdomains of intracellular Ca2+: molecular determinants and functional consequences. Physiol Rev. 2006;86:369–408. doi: 10.1152/physrev.00004.2005. [DOI] [PubMed] [Google Scholar]
  • 46.Fiala JC. Reconstruct: a free editor for serial section microscopy. J Microsc. 2005;218:52–61. doi: 10.1111/j.1365-2818.2005.01466.x. [DOI] [PubMed] [Google Scholar]
  • 47.Weibel ER. Stereological Methods. Vol.1: practical Methods for Biological Morphometry. New York: Academic Press; 1979. [Google Scholar]
  • 48.Popescu LM. Surface microvesicle and calcium homeostasis in vertebrate smooth muscle. In: Diculescu I, et al., editors. Histochemistry and Cytochemistry. Bucharest: SSM Edition; 1976. pp. 280–1. [Google Scholar]
  • 49.Poburko D, Kuo KH, Dai J, Lee CH, Van Breemen C. Organellar junctions promote targeted Ca2+ signaling in smooth muscle: why two membranes are better than one. Trends in Pharmacological Sciences. 2004;25:8–15. doi: 10.1016/j.tips.2003.10.011. [DOI] [PubMed] [Google Scholar]
  • 50.Hommelgaard AM, Roepstorff K, Vilhardt F, Torgersen ML, Sandvig K, van Deurs B. Caveolae: stable membrane domains with a potential for internalization. Traffic. 2005;6:720–4. doi: 10.1111/j.1600-0854.2005.00314.x. [DOI] [PubMed] [Google Scholar]
  • 51.Moore ED, Voigt T, Kobayashi YM, Isenberg G, Fay FS, Gallitelli MF, Franzini-Armstrong C. Organization of Ca2+ release units in excitable smooth muscle of the guinea-pig urinary bladder. Biophys J. 2004;87:1836–47. doi: 10.1529/biophysj.104.044123. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 52.Fameli N, Van Breemen C, Kuo KH. 2006. A quantitative model for refilling of the sarcoplasmic reticulum during vascular smooth muscle asynchronous [Ca2+] oscillations http://arxiv.org/pdf/q-bio.QM/0603001.
  • 53.Popescu LM. Cytochemical study of the intracellular calcium distribution in smooth muscle. In: Casteels R, et al., editors. Excitation-contraction coupling in smooth muscle. Elsevier/North-Holland Biochemical Press; 1977. pp. 13–23. eds. ; [Google Scholar]
  • 54.Popescu LM, Ignat P. Calmodulin-dependent C2+ ATPase of human smooth muscle sarcolemma. Cell Calcium. 1983;4:219–35. doi: 10.1016/0143-4160(83)90001-5. [DOI] [PubMed] [Google Scholar]
  • 55.Fujimoto T. Calcium pump of plasma membrane is localized in caveolae. J Cell Biol. 1993;120:1147–57. doi: 10.1083/jcb.120.5.1147. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 56.Fujimoto T, Nakade S, Miyawaki A, Mikoshiba K, Ogawa K. Localization of inositol 1,4,5-trisphosphate receptor-like protein in plasmalemmal caveolae. J Cell Biol. 1992;119:1507–13. doi: 10.1083/jcb.119.6.1507. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 57.Zhang AY, Li PL. Vascular physiology of Ca2+ mobilizing second messenger - cyclic ADP-ribose. J Cell Mol Med. 2006;2:407–22. doi: 10.1111/j.1582-4934.2006.tb00408.x. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 58.Hofer AM. Another dimension to calcium signaling: a look at extracellular calcium. J Cell Sci. 2005;118:855–62. doi: 10.1242/jcs.01705. [DOI] [PubMed] [Google Scholar]
  • 59.Popescu LM, Ciontea SM, Cretoiu D, Hinescu ME, Radu E, Ionescu N, Ceausu M, Gherghiceanu M, Braga RI, Vasilescu F, Zagrean L, Ardeleanu C. Novel type of interstitial cell (Cajal-like) in human fallopian tube. J Cell Mol Med. 2005;9:479–523. doi: 10.1111/j.1582-4934.2005.tb00376.x. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 60.Ciontea SM, Radu E, Regalia T, Ceafalan L, Cretoiu D, Gherghiceanu M, Braga RI, Malincenco M, Zagrean L, Hinescu ME, Popescu LM. C-kit immunopositive interstitial cells (Cajal-type) in human myometrium. J Cell Mol Med. 2005;9:407–20. doi: 10.1111/j.1582-4934.2005.tb00366.x. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 61.Gherghiceanu M, Popescu LM. Interstitial Cajal-like cells (ICLC) in human resting mammary gland stroma. Transmission electron microscope (TEM) identification. J Cell Mol Med. 2005;9:893–910. doi: 10.1111/j.1582-4934.2005.tb00387.x. [DOI] [PMC free article] [PubMed] [Google Scholar]

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