title: Biophysical characterization of a binding site for TLQP-21, a naturally occurring peptide which induces resistance to obesity.
abstract: Recently, we demonstrated that TLQP-21 triggers lipolysis and induces resistance to obesity by reducing fat accumulation [1]. TLQP-21 is a 21 amino acid peptide cleavage product of the neuroprotein VGF and was first identified in rat brain. Although TLQP-21 biological activity and its molecular signaling is under active investigation, a receptor for TLQP-21 has not yet been characterized. We now demonstrate that TLQP-21 stimulates intracellular calcium mobilization in CHO cells. Furthermore, using Atomic Force Microscopy (AFM), we also provide evidence of TLQP-21 binding-site characteristics in CHO cells. AFM was used in force mapping mode equipped with a cantilever suitably functionalized with TLQP-21. Attraction of this functionalized probe to the cell surface was specific and consistent with the biological activity of TLQP-21; by contrast, there was no attraction of a probe functionalized with biologically inactive analogues. We detected interaction of the peptide with the binding-site by scanning the cell surface with the cantilever tip. The attractive force between TLQP-21 and its binding site was measured, statistically analyzed and quantified at approximately 40 pN on average, indicating a single class of binding sites. Furthermore we observed that the distribution of these binding sites on the surface was relatively uniform.
authors.affiliation: Department of Experimental Medicine, University of Milano-Bicocca, Via Cadore 48, 20900, Monza (MB) Italy. valeria.cassina@unimib.it
authors.forename: V
authors.initials: V
authors.lastname: Cassina
authors.forename: A
authors.initials: A
authors.lastname: Torsello
authors.forename: A
authors.initials: A
authors.lastname: Tempestini
authors.forename: D
authors.initials: D
authors.lastname: Salerno
authors.forename: D
authors.initials: D
authors.lastname: Brogioli
authors.forename: L
authors.initials: L
authors.lastname: Tamiazzo
authors.forename: E
authors.initials: E
authors.lastname: Bresciani
authors.forename: J
authors.initials: J
authors.lastname: Martinez
authors.forename: J A
authors.initials: JA
authors.lastname: Fehrentz
authors.forename: P
authors.initials: P
authors.lastname: Verdié
authors.forename: R J
authors.initials: RJ
authors.lastname: Omeljaniuk
authors.forename: R
authors.initials: R
authors.lastname: Possenti
authors.forename: L
authors.initials: L
authors.lastname: Rizzi
authors.forename: V
authors.initials: V
authors.lastname: Locatelli
authors.forename: F
authors.initials: F
authors.lastname: Mantegazza
mesh_terms: D000818:Animals; D001665:Binding Sites; D001703:Biophysics / Q000379:methods*; D016466:CHO Cells; D002118:Calcium / Q000378:metabolism; D002448:Cell Adhesion; D002462:Cell Membrane / Q000378:metabolism; D006224:Cricetinae; D007031:Hypothalamus / Q000378:metabolism; D008024:Ligands; D051379:Mice; D018625:Microscopy, Atomic Force / Q000379:methods; D008858:Microscopy, Phase-Contrast / Q000379:methods; D008954:Models, Biological; D015233:Models, Statistical; D009765:Obesity / Q000378:metabolism*; D010446:Peptide Fragments / Q000737:chemistry*; D010455:Peptides / Q000737:chemistry*; D051381:Rats; D013997:Time Factors
chemical_list: D008024:Ligands; D010446:Peptide Fragments; D010455:Peptides; C522412:TLQP-21 peptide; D002118:Calcium