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PSMD9–DNAJA1 Novel Interaction Axis Destabilizes and Promotes Proteasomal Degradation of DNAJA1
CC BY 4.0 · Indian J Med Paediatr Oncol 2024; 45(S 01): S1-S16
DOI: DOI: 10.1055/s-0044-1788207
*Corresponding author: (e-mail: vprasanna@actrec.gov.in).
Abstract
Background: PSMD9 is a 26S proteasomal assembly chaperone, overexpressed in many cancers and involved in cellular signaling. Proteomics analysis of PSMD9 overexpression identified DNAJA1, mitochondrial protein transport chaperone, as a putative novel interactor. In this study, we aim to understand the PSMD9–DNAJA1-mediated role in regulating mitochondrial protein transport.
Materials and Methods: Stable PSMD9 overexpressing and knockout clones developed in the lab were used to determine the interaction and associated functions using co-immunoprecipitation, proximity ligation assay, Western blotting, immuno-fluorescence, and qRT-PCR. The PSMD9–DNAJA1 interaction affinity was determined in vitro by ELISA.
Results: The PSMD9–DNAJA1 interaction was confirmed in vitro (Kd in nM range) and ex vivo in PSDM9-overexpressing HEK293 cells. The interaction was also confirmed in MCF7 (endogenously overexpressed PSMD9). This interaction stabilized upon proteasomal inhibition indicating that the interaction promotes enhanced proteasomal degradation of DNAJA1. Enhanced degradation of DNAJA1 may affect its canonical function of transporting newly synthesized mitochondrial protein from cytoplasm to mitochondria. Mitochondrial membrane potential alterations observed on PSMD9 overexpression or knockout confirm this hypothesis. Furthermore, the localization of DNAJA1 was also altered in a PSMD9-dependent manner, where PSMD9 KO resulted in nuclear accumulation of DNAJA1.
Conclusion: The results together indicate that PSMD9 regulates the localization and the stability of DNAJA1. This can influence the efficient transport of mitochondrial proteins and thereby alter cellular and organellar homeostasis.
Publication History
Article published online:
08 July 2024
© 2024. The Author(s). This is an open access article published by Thieme under the terms of the Creative Commons Attribution License, permitting unrestricted use, distribution, and reproduction so long as the original work is properly cited. (https://creativecommons.org/licenses/by/4.0/)
Thieme Medical and Scientific Publishers Pvt. Ltd.
A-12, 2nd Floor, Sector 2, Noida-201301 UP, India
*Corresponding author: (e-mail: vprasanna@actrec.gov.in).
Abstract
Background: PSMD9 is a 26S proteasomal assembly chaperone, overexpressed in many cancers and involved in cellular signaling. Proteomics analysis of PSMD9 overexpression identified DNAJA1, mitochondrial protein transport chaperone, as a putative novel interactor. In this study, we aim to understand the PSMD9–DNAJA1-mediated role in regulating mitochondrial protein transport.
Materials and Methods: Stable PSMD9 overexpressing and knockout clones developed in the lab were used to determine the interaction and associated functions using co-immunoprecipitation, proximity ligation assay, Western blotting, immuno-fluorescence, and qRT-PCR. The PSMD9–DNAJA1 interaction affinity was determined in vitro by ELISA.
Results: The PSMD9–DNAJA1 interaction was confirmed in vitro (Kd in nM range) and ex vivo in PSDM9-overexpressing HEK293 cells. The interaction was also confirmed in MCF7 (endogenously overexpressed PSMD9). This interaction stabilized upon proteasomal inhibition indicating that the interaction promotes enhanced proteasomal degradation of DNAJA1. Enhanced degradation of DNAJA1 may affect its canonical function of transporting newly synthesized mitochondrial protein from cytoplasm to mitochondria. Mitochondrial membrane potential alterations observed on PSMD9 overexpression or knockout confirm this hypothesis. Furthermore, the localization of DNAJA1 was also altered in a PSMD9-dependent manner, where PSMD9 KO resulted in nuclear accumulation of DNAJA1.
Conclusion: The results together indicate that PSMD9 regulates the localization and the stability of DNAJA1. This can influence the efficient transport of mitochondrial proteins and thereby alter cellular and organellar homeostasis.
No conflict of interest has been declared by the author(s).
Publication History
Article published online:
08 July 2024
© 2024. The Author(s). This is an open access article published by Thieme under the terms of the Creative Commons Attribution License, permitting unrestricted use, distribution, and reproduction so long as the original work is properly cited. (https://creativecommons.org/licenses/by/4.0/)
Thieme Medical and Scientific Publishers Pvt. Ltd.
A-12, 2nd Floor, Sector 2, Noida-201301 UP, India