Identification of DNAJA1 as a novel interacting partner and a substrate of human transglutaminase 2

Abstract

Transglutaminase 2 (TG2) is a ubiquitously expressed multifunctional member of the transglutaminase enzyme family. It has been implicated to have roles in many physiological and pathological processes such as differentiation, apoptosis, signal transduction, adhesion and migration, wound healing and inflammation. Previous studies revealed that TG2 has various intra- and extra-cellular interacting partners, which contribute to these processes. In the present study, we identified a molecular co-chaperone, DNAJA1, as a novel interacting partner of human TG2 using a GST pull-down assay and subsequent mass spectrometry analysis, and further confirmed this interaction via ELISA and surface plasmon resonance measurements. Interaction studies were also performed with domain variants of TG2 and results suggest that the catalytic core domain of TG2 is essential for the TG2-DNAJA1 interaction. Cross-linking activity was not essential for the interaction since DNAJA1 was also found to interact with the catalytically inactive form of TG2. Furthermore, we have showed that DNAJA1 interacts with the open form of TG2 and regulates its transamidation activity under both in vitro and in situ conditions. We also found that DNAJA1 is a glutamine donor substrate of TG2. Since DNAJA1 and TG2 are reported to regulate common pathological conditions such as neurodegenerative disorders and cancer, the findings in the present paper open up possibilities to explore molecular mechanisms behind TG2-regulated functions.

The Multifaceted Role of HSF1 in Pathophysiology: Focus on Its Interplay with TG2

“…The peculiar biochemistry of TG2, as well as its capacity to interact with the main proteins involved in the regulation of proteostasis imply that TG2, besides its function in the activation of HSF1, directly regulates the HSPs. Indeed, about 40% of TG2 interacting proteins are related to the chaperone protein family [51] and several studies revealed TG2 interactions with many HSPs such as Hsp70, Hsp27, Hsp90 as well as co-chaperones from the DnaJ and the BAG families [60][61][62][63]. Through these interactions, TG2 is able to modulate cellular processes involved in different pathologies.…”

TG2 regulates the heat‐shock response by the post‐translational modification of HSF1

“…The peculiar biochemistry of this enzyme as well as its capacity to interact with the main proteins involved in the regulation of proteostasis suggests that TG2 plays a key role in this process. For example, among the TG2 intracellular partners, many are molecular chaperones, such as the heat‐shock proteins HSP70, HSP27, HSP90 as well as co‐chaperone from the DNAjs and the BAG families . Indeed, recent compelling evidence places TG2 within the regulation of main pathways controlling the proteome homeostasis as autophagy, proteasome and exosomes .…”

Leveraging the Structure of DNAJA1 to Discover Novel Potential Pancreatic Cancer Therapies

“…In PDAC, it has been proposed that DNAJA1 may regulate the anti-apoptotic state through the hyperphosphorylation of c-Jun [ 4 ]. This mechanism likely involves an unknown protein binding partner of DNAJA1 and is consistent with DNAJA1 being highly networked with proteins associated with pancreatic cancer [ 4 , 5 , 6 , 7 , 9 , 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 ]. For example, DNAJA1 has been observed to stabilize mutant p53 proteins, preventing its degradation, impacting its localization, and allowing p53 to promote metastasis in pancreatic cancer cells.…”