title: Serum response factor and myocardin mediate arterial hypercontractility and cerebral blood flow dysregulation in Alzheimer's phenotype.
abstract: Cerebral angiopathy contributes to cognitive decline and dementia in Alzheimer's disease (AD) through cerebral blood flow (CBF) reductions and dysregulation. We report vascular smooth muscle cells (VSMC) in small pial and intracerebral arteries, which are critical for CBF regulation, express in AD high levels of serum response factor (SRF) and myocardin (MYOCD), two interacting transcription factors that orchestrate a VSMC-differentiated phenotype. Consistent with this finding, AD VSMC overexpressed several SRF-MYOCD-regulated contractile proteins and exhibited a hypercontractile phenotype. MYOCD overexpression in control human cerebral VSMC induced an AD-like hypercontractile phenotype and diminished both endothelial-dependent and -independent relaxation in the mouse aorta ex vivo. In contrast, silencing SRF normalized contractile protein content and reversed a hypercontractile phenotype in AD VSMC. MYOCD in vivo gene transfer to mouse pial arteries increased contractile protein content and diminished CBF responses produced by brain activation in wild-type mice and in two AD models, the Dutch/Iowa/Swedish triple mutant human amyloid beta-peptide (Abeta)-precursor protein (APP)- expressing mice and APPsw(+/-) mice. Silencing Srf had the opposite effect. Expression of SRF did not change in VSMC subjected to Alzheimer's neurotoxin, Abeta. Thus, SRF-MYOCD overexpression in small cerebral arteries appears to initiate independently of Abeta a pathogenic pathway mediating arterial hypercontractility and CBF dysregulation, which are associated with Alzheimer's dementia.
authors.affiliation: Socratech Research Laboratories L.L.C., Department of Neurosurgery, University of Rochester School of Medicine, 601 Elmwood Avenue, Rochester, NY 14642, USA.
authors.forename: Nienwen
authors.initials: N
authors.lastname: Chow
authors.forename: Robert D
authors.initials: RD
authors.lastname: Bell
authors.forename: Rashid
authors.initials: R
authors.lastname: Deane
authors.forename: Jeffrey W
authors.initials: JW
authors.lastname: Streb
authors.forename: Jiyuan
authors.initials: J
authors.lastname: Chen
authors.forename: Andrew
authors.initials: A
authors.lastname: Brooks
authors.forename: William
authors.initials: W
authors.lastname: Van Nostrand
authors.forename: Joseph M
authors.initials: JM
authors.lastname: Miano
authors.forename: Berislav V
authors.initials: BV
authors.lastname: Zlokovic
mesh_terms: D000544:Alzheimer Disease / Q000235:genetics / Q000378:metabolism* / Q000473:pathology*; D000818:Animals; D002478:Cells, Cultured; D002536:Cerebral Arteries / Q000187:drug effects / Q000378:metabolism* / Q000473:pathology*; D006801:Humans; D051379:Mice; D008810:Mice, Inbred C57BL; D009687:Nuclear Proteins / Q000378:metabolism*; D010641:Phenotype; D011189:Potassium Chloride / Q000494:pharmacology; D012039:Regional Blood Flow; D026362:Serum Response Factor / Q000235:genetics / Q000378:metabolism*; D015534:Trans-Activators / Q000378:metabolism*; D000099251:Myocardin
chemical_list: D009687:Nuclear Proteins; D011189:Potassium Chloride; D026362:Serum Response Factor; D015534:Trans-Activators; D000099251:Myocardin