Abnormal myosin phosphatase targeting subunit 1 phosphorylation and actin polymerization contribute to impaired myogenic regulation of cerebral arterial diameter in the type 2 diabetic Goto-Kakizaki rat. Issue 1 (January 2017)

• Record Type: Journal Article
• Authors: Abd-Elrahman, Khaled S; Colinas, Olaia; Walsh, Emma J; Zhu, Hai-Lei; Campbell, Christine M; Walsh, Michael P; Cole, William C
• Is Part Of: Journal of cerebral blood flow & metabolism. Volume 37:Issue 1(2017)
• Page Start: 227
• Page End: 240
• Publication Date: 2017-01
• Subjects: Ca2+ sensitization -- cerebral arteries -- Goto-Kakizaki -- Rho-associated kinase -- type 2 diabetes; Cerebral circulation -- Periodicals; Brain -- Metabolism -- Periodicals; Brain -- Blood-vessels -- Periodicals; Cerebrovascular disease -- Periodicals; 612.824
• DOI: 10.1177/0271678X15622463
• Languages: English
• ISSNs: 0271-678X

Abstract

The myogenic response of cerebral resistance arterial smooth muscle to intraluminal pressure elevation is a key physiological mechanism regulating blood flow to the brain. Rho-associated kinase plays a critical role in the myogenic response by activating Ca 2+ sensitization mechanisms: (i) Rho-associated kinase inhibits myosin light chain phosphatase by phosphorylating its targeting subunit myosin phosphatase targeting subunit 1 (at T855), augmenting 20 kDa myosin regulatory light chain (LC20 ) phosphorylation and force generation; and (ii) Rho-associated kinase stimulates cytoskeletal actin polymerization, enhancing force transmission to the cell membrane. Here, we tested the hypothesis that abnormal Rho-associated kinase-mediated myosin light chain phosphatase regulation underlies the dysfunctional cerebral myogenic response of the Goto-Kakizaki rat model of type 2 diabetes. Basal levels of myogenic tone, LC20, and MYPT1-T855 phosphorylation were elevated and G-actin content was reduced in arteries of pre-diabetic 8–10 weeks Goto-Kakizaki rats with normal serum insulin and glucose levels. Pressure-dependent myogenic constriction, LC20, and myosin phosphatase targeting subunit 1 phosphorylation and actin polymerization were suppressed in both pre-diabetic Goto-Kakizaki and diabetic (18–20 weeks) Goto-Kakizaki rats, whereas RhoA, ROK2, and MYPT1 expression were unaffected. We conclude that abnormal Rho-associated kinase-mediated Ca 2+ sensitization contributes to the dysfunctional cerebral myogenic response in the Goto-Kakizaki model of type 2 diabetes.