Influence of V5/6-His Tag on the Properties of Gap Junction Channels Composed of Connexin43, Connexin40 or Connexin45

HeLa cells expressing wild-type connexin43, connexin40 or connexin45 and connexins fused with a V5/6-His tag to the carboxyl terminus (CT) domain (Cx43-tag, Cx40-tag, Cx45-tag) were used to study connexin expression and the electrical properties of gap junction channels. Immunoblots and immunolabeling indicated that tagged connexins are synthesized and targeted to gap junctions in a similar manner to their wild-type counterparts. Voltage-clamp experiments on cell pairs revealed that tagged connexins form functional channels. Comparison of multichannel and single-channel conductances indicates that tagging reduces the number of operational channels, implying interference with hemichannel trafficking, docking and/or channel opening. Tagging provoked connexin-specific effects on multichannel and single-channel properties. The Cx43-tag was most affected and the Cx45-tag, least. The modifications included (1) Vj-sensitive gating of Ij (Vj, gap junction voltage; Ij, gap junction current), (2) contribution and (3) kinetics of Ij deactivation and (4) single-channel conductance. The first three reflect alterations of fast Vj gating. Hence, they may be caused by structural and/or electrical changes on the CT that interact with domains of the amino terminus and cytoplasmic loop. The fourth reflects alterations of the ion-conducting pathway. Conceivably, mutations at sites remote from the channel pore, e.g., 6-His-tagged CT, affect protein conformation and thus modify channel properties indirectly. Hence, V5/6-His tagging of connexins is a useful tool for expression studies in vivo. However, it should not be ignored that it introduces connexin-dependent changes in both expression level and electrophysiological properties

Cross‐cultural comparison of symptom networks in late‐life major depressive disorder: Yoruba Africans and the Spanish Population

Background: The concept of European psychologisation of depression versus somatisation in non-European populations has been the basis of several studies of cultural psychopathology in the general population. Little is currently known about cross-cultural differences and similarities in late-life depression symptom reporting. We cross-culturally compared symptom reporting in the context of Major Depressive Disorder (MDD) among community-dwelling older adults from Spain and Nigeria. Methods: We relied on data from two household multistage probability samples comprising 3,715 persons aged 65 years or older in the Spanish and Nigerian populations. All participants underwent assessments for MDD using the World Mental Health Survey version of the Composite International Diagnostic Interview. Cross-cultural comparison of broad somatic and psychological categories as well as relationship and influence of individual symptoms were analysed using the Symptom Network Analysis approach. Results: Current MDD was diagnosed in 232 and 195 older persons from Spain and Nigeria, respectively. The symptom network of the two samples were invariant in terms of global strength, S(GSPAIN , GNIGERIA ) = 7.56, P = .06, with psychological and somatic symptoms demonstrating centrality in both countries. However, country-specific relationships and influence of individual symptoms were found in the network structure of both samples, M(GSPAIN , GNIGERIA ) = 2.95, P < .01. Conclusion: Broad somatic and psychological symptoms categories contributed to the structural network of older Africans and their peers from the Spanish population. Variations in the relationship and influence of individual symptoms suggests that the functional and "communicative" role of individual symptoms may be differentiated by context specific imperatives. J Am Geriatr Soc 68:-, 2020.Wellcome TrustUnión EuropeaMinisterio de Economía y CompetitividadInstituto de Salud Carlos IIIDepto. de Medicina Legal, Psiquiatría y PatologíaFac. de MedicinaTRUEpu