Presenter Information

Andrew PhamFollow

Advisor Information

Paul Davis

Location

Room 112

Presentation Type

Oral Presentation

Start Date

1-3-2019 2:30 PM

End Date

1-3-2019 2:45 PM

Abstract

Gap junctions play a vital role in cell to cell intercellular communication. Gap junctions are made of proteins called connexins with connexin43 (Cx43) being the most commonly studied isoform. Post-translational modifications of its carboxyl-terminal (CT) tail regulate the gating and degradation of gap junction channels. Casein kinase I (CK1) phosphorylates residues in between two alpha helical domains (A315 - M320 and D340 - A348) on the CT tail, opening gap junction channels. These two alpha helical domains have been found to dimerize. CK1 phosphorylation is necessary for opening gap junction channels and we hypothesize that this phosphorylation inhibits the dimerization of these alpha helical domains. Here, we characterized the alpha helical domains and their regulatory roles in gap junction communication. Mutants with deletions in alpha helix 1 (ΔH1), alpha helix 2 (ΔH2), or both (ΔH1&2) were made and expressed in HeLa cells. Results showed the absence of a hyperphosphorylated (P3) band in the ΔH1&2 mutant. Localization of the gap junctions to the membrane was unaffected. When treated with Epidermal growth factor, a known closer of gap junctions, inhibition of communication was observed similarly to the wild type but showed relatively less inhibition in the ΔH1 mutant.

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COinS
 
Mar 1st, 2:30 PM Mar 1st, 2:45 PM

Defining the Biological Role of the Connexin43 Carboxyl Terminal Helical Domains

Room 112

Gap junctions play a vital role in cell to cell intercellular communication. Gap junctions are made of proteins called connexins with connexin43 (Cx43) being the most commonly studied isoform. Post-translational modifications of its carboxyl-terminal (CT) tail regulate the gating and degradation of gap junction channels. Casein kinase I (CK1) phosphorylates residues in between two alpha helical domains (A315 - M320 and D340 - A348) on the CT tail, opening gap junction channels. These two alpha helical domains have been found to dimerize. CK1 phosphorylation is necessary for opening gap junction channels and we hypothesize that this phosphorylation inhibits the dimerization of these alpha helical domains. Here, we characterized the alpha helical domains and their regulatory roles in gap junction communication. Mutants with deletions in alpha helix 1 (ΔH1), alpha helix 2 (ΔH2), or both (ΔH1&2) were made and expressed in HeLa cells. Results showed the absence of a hyperphosphorylated (P3) band in the ΔH1&2 mutant. Localization of the gap junctions to the membrane was unaffected. When treated with Epidermal growth factor, a known closer of gap junctions, inhibition of communication was observed similarly to the wild type but showed relatively less inhibition in the ΔH1 mutant.