title: Structural localization and expression of CXCL12 and CXCR4 in rat heart and isolated cardiac myocytes.
abstract: CXCL12 (SDF-1), which binds CXCR4, is involved in several physiological and pathophysiological processes. In heart, this axis seems to play a key role in cardiogenesis and is involved in the neovascularization of ischemic tissues. Rats have three known CXCL12 mRNA isoforms, of which only alpha and gamma are present in the normal heart. However, little is known about CXCL12 protein expression and localization. We investigated the pattern of protein expression and the localization of both CXCR4 and CXCL12 in the heart, using isolated cardiomyocytes and a rat myocardial infarction model. Western blots showed that cardiomyocytes contained a specific 67-kDa CXCR4 isoform and a 12-kDa CXCL12 isoform. Confocal and electron microscopy clearly showed that CXCR4 was present at the plasmalemma and CXCL12 in continuity of the Z-line, in the proximal part of T-tubules. In conclusion, we provide the first description of the expression and fine localization of CXCR4 and CXCL12 proteins in normal rat heart and cardiomyocytes. These results suggest that the CXCL12/CXCR4 axis may be involved in cardiomyocyte calcium homeostasis regulation. Our work and the well-known chemoattraction properties of the CXCL12/CXCR4 axis highlight the importance of deciphering the function of this axis in both normal and pathological hearts.
authors.affiliation: CNRS-UMR 8162, Université Paris XI Sud, Hôpital Marie Lannelongue, 133 avenue de la Résistance, 92350 Le Plessis-Robinson, France. audrey.segret@ccml.u-psud.fr
authors.forename: Audrey
authors.initials: A
authors.lastname: Segret
authors.forename: Catherine
authors.initials: C
authors.lastname: Rücker-Martin
authors.forename: Catherine
authors.initials: C
authors.lastname: Pavoine
authors.forename: Jeanne
authors.initials: J
authors.lastname: Flavigny
authors.forename: Edith
authors.initials: E
authors.lastname: Deroubaix
authors.forename: Marc-Antoine
authors.initials: MA
authors.lastname: Châtel
authors.forename: Alain
authors.initials: A
authors.lastname: Lombet
authors.forename: Jean-François
authors.initials: JF
authors.lastname: Renaud
mesh_terms: D000818:Animals; D054377:Chemokine CXCL12; D019743:Chemokines, CXC / Q000096:biosynthesis / Q000378:metabolism*; D008297:Male; D018613:Microscopy, Confocal; D046529:Microscopy, Electron, Transmission; D009203:Myocardial Infarction / Q000378:metabolism; D009206:Myocardium / Q000378:metabolism* / Q000648:ultrastructure; D032383:Myocytes, Cardiac / Q000378:metabolism* / Q000648:ultrastructure; D020033:Protein Isoforms / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D019718:Receptors, CXCR4 / Q000096:biosynthesis / Q000378:metabolism*
chemical_list: D054377:Chemokine CXCL12; D019743:Chemokines, CXC; C486264:Cxcr4 protein, rat; D020033:Protein Isoforms; D019718:Receptors, CXCR4