Intercellular delivery of therapeutic oligonucleotides.

One promising approach to cancer therapeutics is to induce changes in gene expression that either reduce cancer cell proliferation or induce cancer cell death. Therefore, delivering oligonucleotides (siRNA/miRNA) that target specific genes or gene programs might have a potential therapeutic benefit. The aim of this study was to examine the potential of cell-based delivery of oligonucleotides to cancer cells via two naturally occurring intercellular pathways: gap junctions and vesicular/exosomal traffic.

Lens Connexin Channels Show Differential Permeability to Signaling Molecules.

Gap junction channels mediate the direct intercellular passage of small ions as well as larger solutes such as second messengers. A family of proteins called connexins make up the subunits of gap junction channels in chordate animals. Each individual connexin forms channels that exhibit distinct permeability to molecules that influence cellular signaling, such as calcium ions, cyclic nucleotides, or inositol phosphates.

Connexin43 and connexin50 channels exhibit different permeability to the second messenger inositol triphosphate.

Gap junction channels made of different connexins have distinct permeability to second messengers, which could affect many cell processes, including lens epithelial cell division. Here, we have compared the permeability of IP and Ca through channels made from two connexins, Cx43 and Cx50, that are highly expressed in vertebrate lens epithelial cells. Solute transfer was measured while simultaneously monitoring junctional conductance via dual whole-cell/perforated patch clamp.

A study of the outward background current conductance g, the pacemaker current conductance g, and the gap junction conductance g as determinants of biological pacing in single cells and in a two-cell syncytium using the dynamic clamp.

We previously demonstrated that a two-cell syncytium, composed of a ventricular myocyte and an mHCN2 expressing cell, recapitulated most properties of in vivo biological pacing induced by mHCN2-transfected hMSCs in the canine ventricle. Here, we use the two-cell syncytium, employing dynamic clamp, to study the roles of g (pacemaker conductance), g (background K conductance), and g (intercellular coupling conductance) in biological pacing. We studied g and g in single HEK293 cells expressing cardiac sodium current channel Na1.

Lens Connexin Channels Have Differential Permeability to the Second Messenger cAMP.

Purpose: Gap junction channels exhibit connexin specific biophysical properties, including the selective intercellular passage of larger solutes, such as second messengers. Here, we have examined the cyclic nucleotide permeability of the lens connexins, which could influence events like epithelial cell division and differentiation.

Methods: We compared the cAMP permeability through channels composed of Cx43, Cx46, or Cx50 using simultaneous measurements of junctional conductance and intercellular transfer.