Novel functions of the ER-located Hsp40s DNAJB12 and DNAJB14 on proteins at the outer mitochondrial membrane under stress mediated by CCCP

• Published in: Molecular and cellular biochemistry 2024-10, Vol.479 (10), p.2637-2652
• Main Authors: Sopha, Pattarawut, Meerod, Tirawit, Chantrathonkul, Bunkuea, Phutubtim, Nadgrita, Cyr, Douglas M., Govitrapong, Piyarat
• Format: Article
• Language: English
• Subjects: Apoptosis; Bcl-2 protein; Biochemistry; Biodegradation; Biomedical and Life Sciences; Cancer Research; Cardiology; Chronic exposure; Cytosol; Degradation; Endoplasmic reticulum; Endoplasmic Reticulum - metabolism; Endoplasmic Reticulum Stress; Heat shock proteins; HEK293 Cells; Homeostasis; HSP40 Heat-Shock Proteins - genetics; HSP40 Heat-Shock Proteins - metabolism; Hsp40 protein; Humans; Intracellular signalling; Ion channels; Kinases; Life Sciences; Medical Biochemistry; Membrane proteins; Membranes; Mitochondria; Mitochondrial Membranes - metabolism; Mitochondrial Proteins - genetics; Mitochondrial Proteins - metabolism; Neurodegeneration; Proteasomes; Protein folding; Proteins; PTEN protein; PTEN-induced putative kinase
• ISSN: 0300-8177; 1573-4919; 1573-4919
• DOI: 10.1007/s11010-023-04866-1

The endoplasmic reticulum (ER) membrane provides infrastructure for intracellular signaling, protein degradation, and communication among the ER lumen, cytosol, and nucleus via transmembrane and membrane-associated proteins. Failure to maintain homeostasis at the ER leads to deleterious conditions in humans, such as protein misfolding-related diseases and neurodegeneration. The ER transmembrane heat shock protein 40 (Hsp40) proteins, including DNAJB12 (JB12) and DNAJB14 (JB14), have been studied for their importance in multiple aspects of cellular events, including degradation of misfolded membrane proteins, proteasome-mediated control of proapoptotic Bcl-2 members, and assembly of multimeric ion channels. This study elucidates a novel facet of JB12 and JB14 in that their expression could be regulated in response to stress caused by the presence of ER stressors and the mitochondrial potential uncoupler CCCP. Furthermore, JB14 overexpression could affect the level of PTEN-induced kinase 1 (PINK1) expression under CCCP-mediated stress. Cells with genetic knockout (KO) of DNAJB12 and DNAJB14 exhibited an altered kinetic of phosphorylated Drp1 in response to the stress caused by CCCP treatment. Surprisingly, JB14-KO cells exhibited a prolonged stabilization of PINK1 during chronic exposure to CCCP. Cells depleted with JB12 or JB14 also revealed an increase in the mitochondrial count and branching. Hence, this study indicates the possible novel functions of JB12 and JB14 involving mitochondria in nonstress conditions and under stress caused by CCCP.