GABA_A Receptor-Mediated Currents and Hormone mRNAs in Cells Expressing More Than One Hormone Transcript in Intact Human Pancreatic Islets

• Main Authors: Sergiy V. Korol, Zhe Jin, Bryndis Birnir
• Format: Article
• Language: English
• Published: MDPI AG 2020-01-01
• Series: International Journal of Molecular Sciences
• Subjects: α-like cell; β cell; gaba; glucagon; insulin; mixed-identity cell
• Online Access: https://www.mdpi.com/1422-0067/21/2/600

In pancreatic islets, the major cell-types are &#945;, &#946; and &#948; cells. The &#947;-aminobutyric acid (GABA) signalling system is expressed in human pancreatic islets. In single hormone transcript-expressing cells, we have previously characterized the functional properties of islet GABA_A receptors (iGABA_ARs). Here, we extended these studies to islet cells expressing mRNAs for more than one hormone and sought for correlation between iGABA_AR activity level and relative mRNA expression ratio. The single-cell RT-PCR in combination with the patch-clamp current recordings was used to examine functional properties of iGABA_ARs in the multiple hormone mRNA-expressing cells. We detected cells expressing double (&#945;/&#946;, &#945;/&#948;, &#946;/&#948; cell-types) and triple (&#945;/&#946;/&#948; cell-type) hormone transcripts. The most common mixed-identity cell-type was the &#945;/&#946; group where the cells could be grouped into &#946;- and &#945;-like subgroups. The &#946;-like cells had low <i>GCG</i>/<i>INS</i> expression ratio (&lt;0.6) and significantly higher frequency of iGABA_AR single-channel openings than the &#945;-like cells where the <i>GCG</i>/<i>INS</i> expression ratio was high (&gt;1.2). The hormone expression levels and iGABA_AR single-channel characteristics varied in the &#945;/&#946;/&#948; cell-type. Clearly, multiple hormone transcripts can be expressed in islet cells whereas iGABA_AR single-channel functional properties appear to be &#945; or &#946; cell specific.