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The Cx43-like connexin protein Cx40.8 is differentially localized during fin ontogeny and fin regeneration.

Gerhart SV, Eble DM, Burger RM, Oline SN, Vacaru A, Sadler KC, Jefferis R, Iovine MK - PLoS ONE (2012)

Bottom Line: Previously, we found that a Cx43-like connexin, cx40.8, is co-expressed with cx43 in the population of proliferating cells during fin regeneration.During fin ontogeny, Cx40.8 is found at the plasma membrane, but Cx40.8 is retained in the Golgi apparatus during regeneration.Together our findings reveal that Cx40.8 exhibits differential subcellular localization in vivo, dependent on a discrete domain in its carboxy terminus.

View Article: PubMed Central - PubMed

Affiliation: Department of Biological Sciences, Lehigh University, Bethlehem, Pennsylvania, United States of America.

ABSTRACT
Connexins (Cx) are the subunits of gap junctions, membraneous protein channels that permit the exchange of small molecules between adjacent cells. Cx43 is required for cell proliferation in the zebrafish caudal fin. Previously, we found that a Cx43-like connexin, cx40.8, is co-expressed with cx43 in the population of proliferating cells during fin regeneration. Here we demonstrate that Cx40.8 exhibits novel differential subcellular localization in vivo, depending on the growth status of the fin. During fin ontogeny, Cx40.8 is found at the plasma membrane, but Cx40.8 is retained in the Golgi apparatus during regeneration. We next identified a 30 amino acid domain of Cx40.8 responsible for its dynamic localization. One possible explanation for the differential localization is that Cx40.8 contributes to the regulation of Cx43 in vivo, perhaps modifying channel activity during ontogenetic growth. However, we find that the voltage-gating properties of Cx40.8 are similar to Cx43. Together our findings reveal that Cx40.8 exhibits differential subcellular localization in vivo, dependent on a discrete domain in its carboxy terminus. We suggest that the dynamic localization of Cx40.8 differentially influences Cx43-dependent cell proliferation during ontogeny and regeneration.

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Cx40.8 is localized to different subcellular compartments during ontogeny and regeneration.(A) During ontogeny, Cx40.8 immunofluorescence (green) on whole fins counterstained with propidium iodide (red) shows that Cx40.8 locates to the plasma membrane and vesicles. (B) During regeneration, Cx40.8 is intracellular and staining is consistent with the Golgi apparatus.
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pone-0031364-g002: Cx40.8 is localized to different subcellular compartments during ontogeny and regeneration.(A) During ontogeny, Cx40.8 immunofluorescence (green) on whole fins counterstained with propidium iodide (red) shows that Cx40.8 locates to the plasma membrane and vesicles. (B) During regeneration, Cx40.8 is intracellular and staining is consistent with the Golgi apparatus.

Mentions: Next, Cx40.8 localization in fins was evaluated during ontogenetic and regenerative growth by confocal microscopy (Figure 2). During fin regeneration, Cx40.8 is found intracellularly in crescent-like structures adjacent to the nuclei, consistent with localization in the Golgi apparatus (Figure 2B). These results were consistent with previous findings that Cx40.8-EGFP remains in intracellular vesicles in HeLa cells, and were therefore not unexpected. In contrast, during ontogeny, Cx40.8 is observed at the plasma membrane (Figure 2A), suggesting a dynamic localization of Cx40.8 that depends on growth status of the fin. Importantly, Cx43 was not found to exhibit differential localization, but is located at the plasma membrane during both ontogeny and regeneration [12]. Thus, given that the Cx43 and Cx40.8 antibodies exhibit distinct immunolocalization patterns in regenerating fins, the newly developed Cx40.8 antibody does not cross-react with endogenous Cx43. Our findings described above reveal that during the relatively slow growth of ontogeny, Cx40.8 is located at the plasma membrane. During the relatively rapid growth of regeneration, Cx40.8 is located intracellularly. Together with our previous findings that cx43 and cx40.8 are co-expressed in the population of dividing cells [17], and that Cx43 is required for cell proliferation [12], it is possible that Cx40.8 localization to the plasma membrane attenuates Cx43-dependent cell proliferation during ontogeny.


The Cx43-like connexin protein Cx40.8 is differentially localized during fin ontogeny and fin regeneration.

Gerhart SV, Eble DM, Burger RM, Oline SN, Vacaru A, Sadler KC, Jefferis R, Iovine MK - PLoS ONE (2012)

Cx40.8 is localized to different subcellular compartments during ontogeny and regeneration.(A) During ontogeny, Cx40.8 immunofluorescence (green) on whole fins counterstained with propidium iodide (red) shows that Cx40.8 locates to the plasma membrane and vesicles. (B) During regeneration, Cx40.8 is intracellular and staining is consistent with the Golgi apparatus.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3275562&req=5

pone-0031364-g002: Cx40.8 is localized to different subcellular compartments during ontogeny and regeneration.(A) During ontogeny, Cx40.8 immunofluorescence (green) on whole fins counterstained with propidium iodide (red) shows that Cx40.8 locates to the plasma membrane and vesicles. (B) During regeneration, Cx40.8 is intracellular and staining is consistent with the Golgi apparatus.
Mentions: Next, Cx40.8 localization in fins was evaluated during ontogenetic and regenerative growth by confocal microscopy (Figure 2). During fin regeneration, Cx40.8 is found intracellularly in crescent-like structures adjacent to the nuclei, consistent with localization in the Golgi apparatus (Figure 2B). These results were consistent with previous findings that Cx40.8-EGFP remains in intracellular vesicles in HeLa cells, and were therefore not unexpected. In contrast, during ontogeny, Cx40.8 is observed at the plasma membrane (Figure 2A), suggesting a dynamic localization of Cx40.8 that depends on growth status of the fin. Importantly, Cx43 was not found to exhibit differential localization, but is located at the plasma membrane during both ontogeny and regeneration [12]. Thus, given that the Cx43 and Cx40.8 antibodies exhibit distinct immunolocalization patterns in regenerating fins, the newly developed Cx40.8 antibody does not cross-react with endogenous Cx43. Our findings described above reveal that during the relatively slow growth of ontogeny, Cx40.8 is located at the plasma membrane. During the relatively rapid growth of regeneration, Cx40.8 is located intracellularly. Together with our previous findings that cx43 and cx40.8 are co-expressed in the population of dividing cells [17], and that Cx43 is required for cell proliferation [12], it is possible that Cx40.8 localization to the plasma membrane attenuates Cx43-dependent cell proliferation during ontogeny.

Bottom Line: Previously, we found that a Cx43-like connexin, cx40.8, is co-expressed with cx43 in the population of proliferating cells during fin regeneration.During fin ontogeny, Cx40.8 is found at the plasma membrane, but Cx40.8 is retained in the Golgi apparatus during regeneration.Together our findings reveal that Cx40.8 exhibits differential subcellular localization in vivo, dependent on a discrete domain in its carboxy terminus.

View Article: PubMed Central - PubMed

Affiliation: Department of Biological Sciences, Lehigh University, Bethlehem, Pennsylvania, United States of America.

ABSTRACT
Connexins (Cx) are the subunits of gap junctions, membraneous protein channels that permit the exchange of small molecules between adjacent cells. Cx43 is required for cell proliferation in the zebrafish caudal fin. Previously, we found that a Cx43-like connexin, cx40.8, is co-expressed with cx43 in the population of proliferating cells during fin regeneration. Here we demonstrate that Cx40.8 exhibits novel differential subcellular localization in vivo, depending on the growth status of the fin. During fin ontogeny, Cx40.8 is found at the plasma membrane, but Cx40.8 is retained in the Golgi apparatus during regeneration. We next identified a 30 amino acid domain of Cx40.8 responsible for its dynamic localization. One possible explanation for the differential localization is that Cx40.8 contributes to the regulation of Cx43 in vivo, perhaps modifying channel activity during ontogenetic growth. However, we find that the voltage-gating properties of Cx40.8 are similar to Cx43. Together our findings reveal that Cx40.8 exhibits differential subcellular localization in vivo, dependent on a discrete domain in its carboxy terminus. We suggest that the dynamic localization of Cx40.8 differentially influences Cx43-dependent cell proliferation during ontogeny and regeneration.

Show MeSH
Related in: MedlinePlus