title: Insulin directly stimulates VEGF-A production in the glomerular podocyte.
abstract: Podocytes are critically important for maintaining the integrity of the glomerular filtration barrier and preventing albuminuria. Recently, it has become clear that to achieve this, they need to be insulin sensitive and produce an optimal amount of VEGF-A. In other tissues, insulin has been shown to regulate VEGF-A release, but this has not been previously examined in the podocyte. Using in vitro and in vivo approaches, in the present study, we now show that insulin regulates VEGF-A in the podocyte in both mice and humans via the insulin receptor (IR). Insulin directly increased VEGF-A mRNA levels and protein production in conditionally immortalized wild-type human and murine podocytes. Furthermore, when podocytes were rendered insulin resistant in vitro (using stable short hairpin RNA knockdown of the IR) or in vivo (using transgenic podocyte-specific IR knockout mice), podocyte VEGF-A production was impaired. Importantly, in vivo, this occurs before the development of any podocyte damage due to podocyte insulin resistance. Modulation of VEGF-A by insulin in the podocyte may be another important factor in the development of glomerular disease associated with conditions in which insulin signaling to the podocyte is deranged.
authors.affiliation: Academic and Children's Renal Unit, University of Bristol, Learning and Research building, Southmead Hospital, Bristol, United Kingdom.
authors.forename: L J
authors.initials: LJ
authors.lastname: Hale
authors.forename: J
authors.initials: J
authors.lastname: Hurcombe
authors.forename: A
authors.initials: A
authors.lastname: Lay
authors.forename: B
authors.initials: B
authors.lastname: Santamaría
authors.forename: A M
authors.initials: AM
authors.lastname: Valverde
authors.forename: M A
authors.initials: MA
authors.lastname: Saleem
authors.forename: P W
authors.initials: PW
authors.lastname: Mathieson
authors.forename: G I
authors.initials: GI
authors.lastname: Welsh
authors.forename: R J
authors.initials: RJ
authors.lastname: Coward
mesh_terms: D000818:Animals; D006801:Humans; D007328:Insulin / Q000378:metabolism*; D007333:Insulin Resistance; D051379:Mice; D018345:Mice, Knockout; D050199:Podocytes / Q000378:metabolism*; D012333:RNA, Messenger / Q000378:metabolism; D042461:Vascular Endothelial Growth Factor A / Q000378:metabolism*
chemical_list: D007328:Insulin; D012333:RNA, Messenger; D042461:Vascular Endothelial Growth Factor A; C467480:vascular endothelial growth factor A, mouse
keywords: insulin; podocyte; podocyte-specific insulin receptor knockout mice; vascular endothelial growth factor-A