Connexins: synthesis, post-translational modifications, and trafficking in health and disease

Connexins are tetraspan transmembrane proteins that form gap junctions and facilitate direct intercellular communication, a critical feature for the development, function, and homeostasis of tissues and organs. In addition, a growing number of gap junction-independent functions are being ascribed to these proteins. The connexin gene family is under extensive regulation at the transcriptional and post-transcriptional level, and undergoes numerous modifications at the protein level, including phosphorylation, which ultimately affects their trafficking, stability, and function. Here, we summarize these key regulatory events, with emphasis on how these affect connexin multifunctionality in health and disease

Cx43 and Associated Cell Signaling Pathways Regulate Tunneling Nanotubes in Breast Cancer Cells

Altres ajuts: A. acknowledges funding from Fundación Científica Asociación Española Contra el Cáncer (IDEAS SEMILLA AECC 2020/IDEAS20033PUIG) and Instituto de Salud Carlos III co-financed by the European Regional Development Fund (ERDF) . The APC was funded by Instituto de Salud Carlos III co-financed by the European Regional Development Fund (ERDF). H.G is funded by the European Regional Development Fund (ERDF) through the Operational Program for Competitiveness Factors (COMPETE; under the projects PAC "NETDIAMOND" POCI-01-0145-FEDER-016385; HealthyAging2020 CENTRO-01-0145-FEDER-000012-N2323; POCI-01-0145-FEDER-007440, CENTRO-01-0145-FEDER-032179, CENTRO-01-0145-FEDER-032414, POCI-01-0145-FEDER-022122, FCTUID/NEU/04539/2013, UID/NEU/04539/2019, UIDB/04539/2020 and UIDP/04539/2020.Connexin 43 (Cx43) forms gap junctions that mediate the direct intercellular diffusion of ions and small molecules between adjacent cells. Cx43 displays both pro- and anti-tumorigenic properties, but the mechanisms underlying these characteristics are not fully understood. Tunneling nanotubes (TNTs) are long and thin membrane projections that connect cells, facilitating the exchange of not only small molecules, but also larger proteins, organelles, bacteria, and viruses. Typically, TNTs exhibit increased formation under conditions of cellular stress and are more prominent in cancer cells, where they are generally thought to be pro-metastatic and to provide growth and survival advantages. Cx43 has been described in TNTs, where it is thought to regulate small molecule diffusion through gap junctions. Here, we developed a high-fidelity CRISPR/Cas9 system to knockout (KO) Cx43. We found that the loss of Cx43 expression was associated with significantly reduced TNT length and number in breast cancer cell lines. Notably, secreted factors present in conditioned medium stimulated TNTs more potently when derived from Cx43-expressing cells than from KO cells. Moreover, TNT formation was significantly induced by the inhibition of several key cancer signaling pathways that both regulate Cx43 and are regulated by Cx43, including RhoA kinase (ROCK), protein kinase A (PKA), focal adhesion kinase (FAK), and p38. Intriguingly, the drug-induced stimulation of TNTs was more potent in Cx43 KO cells than in wild-type (WT) cells. In conclusion, this work describes a novel non-canonical role for Cx43 in regulating TNTs, identifies key cancer signaling pathways that regulate TNTs in this setting, and provides mechanistic insight into a pro-tumorigenic role of Cx43 in cancer

Proteïnes quinases i càncer: desenvolupament d'un assaig bioquímic per a detectar inhibidors del receptor del factor epidèrmic del creixement

Tercer premi del VII Premi PRBB al millor treball de recerca en Ciències de la Salut i de la VidaTreball tutoritzat per M. Teresa Pla-Giribert de l'Institut Pere Calders (Cerdanyola del Vallès)L’EGFR és una proteïna quinasa de membrana implicada en el funcionament correcte de processos com la regulació del cicle cel·lular i la divisió, i que es troba sobrexpressada i/o desregulada en una gran varietat de tumors./nDegut a la relació que diversos estudis científics han pogut establir entre la sobreexpresió d’aquest receptor i la supervivència de les cèl·lules canceroses, així com també la resistència d’aquestes a la radioteràpia i la quimioteràpia, l’EGFR és una diana molt interessant per desenvolupar un fàrmac contra el càncer. /nEl principal objectiu d’aquest projecte es desenvolupar un assaig bioquímic que ens permeti identificar nous compostos químics inhibidors que puguin potencialment bloquejar l’activitat de l’EGFR, independentment del domini del receptor amb el que interactuïn./nPer aconseguir-ho, ha estat utilitzat un mètode basat en la quantificació de l’ATP

Cx43 and Associated Cell Signaling Pathways Regulate Tunneling Nanotubes in Breast Cancer Cells

Altres ajuts: A. acknowledges funding from Fundación Científica Asociación Española Contra el Cáncer (IDEAS SEMILLA AECC 2020/IDEAS20033PUIG) and Instituto de Salud Carlos III co-financed by the European Regional Development Fund (ERDF) . The APC was funded by Instituto de Salud Carlos III co-financed by the European Regional Development Fund (ERDF). H.G is funded by the European Regional Development Fund (ERDF) through the Operational Program for Competitiveness Factors (COMPETE; under the projects PAC "NETDIAMOND" POCI-01-0145-FEDER-016385; HealthyAging2020 CENTRO-01-0145-FEDER-000012-N2323; POCI-01-0145-FEDER-007440, CENTRO-01-0145-FEDER-032179, CENTRO-01-0145-FEDER-032414, POCI-01-0145-FEDER-022122, FCTUID/NEU/04539/2013, UID/NEU/04539/2019, UIDB/04539/2020 and UIDP/04539/2020.Connexin 43 (Cx43) forms gap junctions that mediate the direct intercellular diffusion of ions and small molecules between adjacent cells. Cx43 displays both pro- and anti-tumorigenic properties, but the mechanisms underlying these characteristics are not fully understood. Tunneling nanotubes (TNTs) are long and thin membrane projections that connect cells, facilitating the exchange of not only small molecules, but also larger proteins, organelles, bacteria, and viruses. Typically, TNTs exhibit increased formation under conditions of cellular stress and are more prominent in cancer cells, where they are generally thought to be pro-metastatic and to provide growth and survival advantages. Cx43 has been described in TNTs, where it is thought to regulate small molecule diffusion through gap junctions. Here, we developed a high-fidelity CRISPR/Cas9 system to knockout (KO) Cx43. We found that the loss of Cx43 expression was associated with significantly reduced TNT length and number in breast cancer cell lines. Notably, secreted factors present in conditioned medium stimulated TNTs more potently when derived from Cx43-expressing cells than from KO cells. Moreover, TNT formation was significantly induced by the inhibition of several key cancer signaling pathways that both regulate Cx43 and are regulated by Cx43, including RhoA kinase (ROCK), protein kinase A (PKA), focal adhesion kinase (FAK), and p38. Intriguingly, the drug-induced stimulation of TNTs was more potent in Cx43 KO cells than in wild-type (WT) cells. In conclusion, this work describes a novel non-canonical role for Cx43 in regulating TNTs, identifies key cancer signaling pathways that regulate TNTs in this setting, and provides mechanistic insight into a pro-tumorigenic role of Cx43 in cancer