title: Rab11a and its binding partners regulate the recycling of the ß1-adrenergic receptor.
abstract: ß1-adrenergic receptors (ß1-AR) are internalized in response to agonists and then recycle back for another round of signaling. The serine 312 to alanine mutant of the ß1-AR (S312A) is internalized but does not recycle. We determined that WT ß1-AR and S312A were internalized initially to an early sorting compartment because they colocalized by >70% with the early endosomal markers rab5a and early endosomal antigen-1 (EEA1). Subsequently, the WT ß1-AR trafficked via rab4a-expressing sorting endosomes to recycling endosomes. In recycling endosomes WT ß1-AR were colocalized by >70% with the rab11 GTPase. S312A did not colocalize with either rab4a or rab11, instead they exited from early endosomes to late endosomes/lysosomes in which they were degraded. Rab11a played a prominent role in recycling of the WT ß1-AR because dominant negative rab11a inhibited, while constitutively active rab11a accelerated the recycling of the ß1-AR. Next, we determined the effect of each of the rab11-interacting proteins on trafficking of the WT ß1-AR. The recycling of the ß1-AR was markedly inhibited when myosin Vb, FIP2, FIP3 and rabphillin were knocked down. These data indicate that rab11a and a select group of its binding partners play a prominent role in recycling of the human ß1-AR.
authors: Department of Neurology, University of Tennessee Health Sciences Center, Memphis, TN 38163, USA.
authors: Lidia A
authors: LA
authors: Gardner
authors: Hassan
authors: H
authors: Hajjhussein
authors: Katherine C
authors: KC
authors: Frederick-Dyer
authors: Suleiman W
authors: SW
authors: Bahouth
mesh_terms: D000318:Adrenergic beta-Agonists / Q000494:pharmacology; D019943:Amino Acid Substitution; D002460:Cell Line; D011992:Endosomes / Q000378:metabolism; D006801:Humans; D051550:I-kappa B Kinase / Q000235:genetics / Q000378:metabolism; D007545:Isoproterenol / Q000494:pharmacology; D008247:Lysosomes / Q000378:metabolism; D016297:Mutagenesis, Site-Directed; D018995:Myosin Heavy Chains / Q000235:genetics / Q000378:metabolism; D024701:Myosin Type V / Q000235:genetics / Q000378:metabolism; D034622:RNA Interference; D018342:Receptors, Adrenergic, beta-1 / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D033921:Vesicular Transport Proteins / Q000378:metabolism; D020691:rab GTP-Binding Proteins / Q000378:metabolism* / Q000502:physiology; D020695:rab4 GTP-Binding Proteins / Q000378:metabolism / Q000502:physiology; D000099193:rab11 GTP-Binding Proteins
chemical_list: D000318:Adrenergic beta-Agonists; D051550:I-kappa B Kinase; D007545:Isoproterenol; D018995:Myosin Heavy Chains; D024701:Myosin Type V; D018342:Receptors, Adrenergic, beta-1; D033921:Vesicular Transport Proteins; D020691:rab GTP-Binding Proteins; D020695:rab4 GTP-Binding Proteins; D000099193:rab11 GTP-Binding Proteins; C491731:IKBKG protein, human; C505832:MYO5B protein, human; C093846:early endosome antigen 1