Gap junctions are essential to normal tissue physiology, providing a direct intercellular pathway for cell to cell signaling and impulse conduction. Mutations in the genes of their subunit protein (connexins) have been linked to a number of human diseases. For instance, mutations in connexin40 (Cx40) have been associated with atrial fibrillation and other arrhythmias. Three Cx40 mutations (A96S, M163V and G38D) that correlate with atrial fibrillation have been previously shown to retain the ability to form conductive gap junction channels in vitro. Our recent publication demonstrates that two of the three have the same unitary conductance and voltage dependent behaviors as wild-type Cx40, while the third one has a significantly higher unitary conductance. All three mutants have altered permeability characteristics relative to wild-type channels. An increasing amount of evidence today indicates the important role of microRNAs in the pathogenesis and development of heart diseases. The data suggest another and as of yet untested possibility; these connexin mutants might affect cardiac conduction and pacing via altered permeability to microRNAs within the myocardium, which themselves target specific membrane K+ channels, IK1 (KCNJ2/Kir2.1) and IKr (HERG), that participate in conduction and pacemaking activities. It was recently reported that the microRNA miR-26 regulates IK1 expression and is down regulated in atrial fibrillation. miR-212 has also been shown to affect IK1 expression, whereas IKr expression is affected by miR-133. In this proposed study we will test if pacemaker activity can be modulated by connexin permeability to microRNAs/siRNAs that in turn regulate gene expression of specific membrane channels associated with pacemaker-like activity.
In Aim 1 we will determine the permeability of gap junction channels formed by disease-linked mutations in Cx40 to miR-26, miR-212, miR-133, and siRNAs specific to IK1 and IKr, respectively, while simultaneously monitoring junctional conductance and cell to cell flux of microRNAs/siRNAs.
In Aim 2 we will use a two-cell pacemaker model (a heterologous pair comprised of a source cell and a cardiac myocyte) to explore effects on pacemaker activity, by cellularly delivering microRNAs and siRNAs that target IK1 and IKr. Thereafter, in Aim3, we will analyze these results using our dynamic clamp model in order to add and subtract relevant currents associated with pacemaker activity to/from a single cell, a coupled pair, or two uncoupled cells paired electronically. In this proposed study, using a cellular biophysical approach, we seek to define if the permeability of gap junction channels might be an essential component in a process of dynamic gene expression that ultimately affects cellular and tissue functions in normal physiology and disease states.

Public Health Relevance

Gap junctions are essential in normal tissue physiology, providing a direct intercellular pathway for cell to cell signaling and impulse conduction. Mutations in their connexin genes have been linked to a number of human diseases, including atrial fibrillation. Increasing contemporary evidence indicates the important role of microRNA in the pathogenesis and development of heart diseases. These, in turn, regulate gene expression of specific membrane channels that are associated with pacemaking activity. This proposal seeks to qualitatively and quantitatively evaluate the permeability of both wild-type and disease associated (atrial fibrillation) mutant connexins to specific microRNAs. The results of this proposed research will establish a baseline for understanding the role of gap junction permeability to microRNAs as a potential factor in disease states like atrial fibrillation.

Agency
National Institute of Health (NIH)
Institute
National Institute of General Medical Sciences (NIGMS)
Type
Research Project (R01)
Project #
5R01GM088181-08
Application #
9690112
Study Section
Intercellular Interactions Study Section (ICI)
Program Officer
Nie, Zhongzhen
Project Start
2011-05-01
Project End
2021-04-30
Budget Start
2019-05-01
Budget End
2020-04-30
Support Year
8
Fiscal Year
2019
Total Cost
Indirect Cost
Name
State University New York Stony Brook
Department
Physiology
Type
Schools of Medicine
DUNS #
804878247
City
Stony Brook
State
NY
Country
United States
Zip Code
11794
Carpintero-Fernandez, Paula; Gago-Fuentes, Raquel; Wang, Hong Z et al. (2018) Intercellular communication via gap junction channels between chondrocytes and bone cells. Biochim Biophys Acta Biomembr 1860:2499-2505
Valiunas, Virginijus; Cohen, Ira S; Brink, Peter R (2018) Defining the factors that affect solute permeation of gap junction channels. Biochim Biophys Acta Biomembr 1860:96-101
Valiunas, Virginijus; Wang, Hong-Zhang; Li, Ling et al. (2015) A comparison of two cellular delivery mechanisms for small interfering RNA. Physiol Rep 3:
Santa Cruz, Ana; Me?e, Gülistan; Valiuniene, Laima et al. (2015) Altered conductance and permeability of Cx40 mutations associated with atrial fibrillation. J Gen Physiol 146:387-98
Mayan, Maria D; Gago-Fuentes, Raquel; Carpintero-Fernandez, Paula et al. (2015) Articular chondrocyte network mediated by gap junctions: role in metabolic cartilage homeostasis. Ann Rheum Dis 74:275-84
Clausen, Chris; Valiunas, Virginijus; Brink, Peter R et al. (2013) MATLAB implementation of a dynamic clamp with bandwidth of >125 kHz capable of generating I Na at 37 °C. Pflugers Arch 465:497-507
Mayan, Maria D; Carpintero-Fernandez, Paula; Gago-Fuentes, Raquel et al. (2013) Human articular chondrocytes express multiple gap junction proteins: differential expression of connexins in normal and osteoarthritic cartilage. Am J Pathol 182:1337-46
Kaufman, Joshua; Gordon, Chris; Bergamaschi, Roberto et al. (2013) The effects of the histone deacetylase inhibitor 4-phenylbutyrate on gap junction conductance and permeability. Front Pharmacol 4:111
Valiunas, Virginijus (2013) Cyclic nucleotide permeability through unopposed connexin hemichannels. Front Pharmacol 4:75
Kanaporis, G; Brink, P R; Valiunas, V (2011) Gap junction permeability: selectivity for anionic and cationic probes. Am J Physiol Cell Physiol 300:C600-9

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