title: Class IA phosphoinositide 3-kinase regulates heart size and physiological cardiac hypertrophy.
abstract: Class I(A) phosphoinositide 3-kinases (PI3Ks) are activated by growth factor receptors, and they regulate, among other processes, cell growth and organ size. Studies using transgenic mice overexpressing constitutively active and dominant negative forms of the p110alpha catalytic subunit of class I(A) PI3K have implicated the role of this enzyme in regulating heart size and physiological cardiac hypertrophy. To further understand the role of class I(A) PI3K in controlling heart growth and to circumvent potential complications from the overexpression of dominant negative and constitutively active proteins, we generated mice with muscle-specific deletion of the p85alpha regulatory subunit and germ line deletion of the p85beta regulatory subunit of class I(A) PI3K. Here we show that mice with cardiac deletion of both p85 subunits exhibit attenuated Akt signaling in the heart, reduced heart size, and altered cardiac gene expression. Furthermore, exercise-induced cardiac hypertrophy is also attenuated in the p85 knockout hearts. Despite such defects in postnatal developmental growth and physiological hypertrophy, the p85 knockout hearts exhibit normal contractility and myocardial histology. Our results therefore provide strong genetic evidence that class I(A) PI3Ks are critical regulators for the developmental growth and physiological hypertrophy of the heart.
authors.affiliation: Division of Systems Biology, Harvard Medical School, Beth Israel Deaconess Medical Center, 77 Avenue Louis Pasteur, 10th Floor, Boston, MA 02115, USA.
authors.forename: Ji
authors.initials: J
authors.lastname: Luo
authors.forename: Julie R
authors.initials: JR
authors.lastname: McMullen
authors.forename: Cassandra L
authors.initials: CL
authors.lastname: Sobkiw
authors.forename: Li
authors.initials: L
authors.lastname: Zhang
authors.forename: Adam L
authors.initials: AL
authors.lastname: Dorfman
authors.forename: Megan C
authors.initials: MC
authors.lastname: Sherwood
authors.forename: M Nicole
authors.initials: MN
authors.lastname: Logsdon
authors.forename: James W
authors.initials: JW
authors.lastname: Horner
authors.forename: Ronald A
authors.initials: RA
authors.lastname: DePinho
authors.forename: Seigo
authors.initials: S
authors.lastname: Izumo
authors.forename: Lewis C
authors.initials: LC
authors.lastname: Cantley
mesh_terms: D000222:Adaptation, Physiological; D000818:Animals; D006332:Cardiomegaly / Q000473:pathology / Q000503:physiopathology; D020134:Catalytic Domain / Q000235:genetics / Q000502:physiology; D002478:Cells, Cultured; D005786:Gene Expression Regulation; D006321:Heart / Q000033:anatomy & histology* / Q000502:physiology*; D051379:Mice; D018345:Mice, Knockout; D032342:Muscle Cells / Q000473:pathology; D009206:Myocardium / Q000201:enzymology / Q000473:pathology; D051058:Oncogene Protein v-akt / Q000378:metabolism; D019869:Phosphatidylinositol 3-Kinases / Q000235:genetics / Q000502:physiology*; D010805:Physical Conditioning, Animal; D015398:Signal Transduction
chemical_list: D019869:Phosphatidylinositol 3-Kinases; D051058:Oncogene Protein v-akt