Roles of CCM-MEKK3 signaling in cardiac development and CCM disease / Zinan Zhou.

Format:

Book

Manuscript

Thesis/Dissertation

Author/Creator:

Zhou, Zinan, author.

Contributor:

Kahn, Mark L., degree supervisor.

Blendy, Julie A., degree supervisor.

Levy, Robert J., degree committee member.

Epstein, Jonathan A., degree committee member.

Klein, Peter S., degree committee member.

Morrisey, Edward E., degree committee member.

University of Pennsylvania. Department of Pharmacology, degree granting institution.

Language:

English

Subjects (All):

Penn dissertations--Pharmacology.

Pharmacology--Penn dissertations.

Local Subjects:

Penn dissertations--Pharmacology.

Pharmacology--Penn dissertations.

Physical Description:

xii, 130 leaves : illustrations ; 29 cm

Production:

[Philadelphia, Pennsylvania] : University of Pennsylvania, 2016.

Summary:

Cerebral cavernous malformations are relatively common vascular malformations. This disease is caused by loss-of-function mutations of KRIT1 (CCM1), CCM2 and PDCD10 (CCM3), which encode the three CCM proteins. These three CCM proteins form an intracellular adaptor protein complex and are required by endothelial cells for vascular development during embryogenesis and preventing the formation of CCM lesions after birth. However, roles of CCM signaling in the developing heart and the molecular mechanism underneath the pathogenesis of CCMs are not known. By applying a combination of mutant zebrafish and mouse models, morpholino gene knockdown in zebrafish, and cell culture, we determined roles of CCM signaling in both cardiac development and CCM formation. Our experiments reveal that loss of CCM signaling in endocardial cells results in mid-gestation heart failure due to premature degradation of cardiac jelly. Loss of CCM signaling dramatically increases endocardial expression of Klf2 and Klf4 transcription factors and the Adamts4 and Adamts5 metalloproteinases that degrade cardiac jelly. These changes in gene expression result from increased activity of MEKK3, a mitogen-activated protein kinase that binds CCM2 in endothelial cells. MEKK3 is both necessary and sufficient for expression of these genes, and partial loss of MEKK3 rescues cardiac defects in CCM-deficient embryos. These findings reveal that CCM signaling controls endothelial gene expression by repressing MEKK3 activity during cardiovascular development. Using a neonatal mouse model of CCM disease, we show that expression of the MEKK3 target genes Klf2 and Klf4, as well as Rho and ADAMTS protease activity, are increased in the endothelial cells of early CCM lesions. Endothelial-specific loss of Map3k3 (also known as Mekk3), Klf2 or Klf4 markedly prevents lesion formation, reverses the increase in Rho activity, and rescues lethality. Consistent with these findings in mice, we show that endothelial expression of KLF2 and KLF4 is increased in human familial and sporadic CCM lesions, and that a disease-causing human CCM2 mutation abrogates the MEKK3 interaction without affecting CCM complex formation. These studies identify gain of MEKK3 signaling and KLF2/4 function as causal mechanisms for CCM pathogenesis that may be targeted to develop new CCM therapeutics.

Notes:

Ph. D. University of Pennsylvania 2016.

Department: Pharmacology.

Supervisor: Mark L. Kahn; Julie A. Blendy.

Includes bibliographical references.

OCLC:

971356462