Tangri, A. | Search bioRxiv

bioRxiv2025

14-3-3ε, a universal adaptor protein, could bind to the tail domain of Kinesin-2 motor subunit KIF3B

KIF3A/KIF3B/KAP complex is a subfamily of kinesin-2 proteins and is known to transport cargoes like N-cadherin, Rab4 vesicles, Par3-Par6-aPKC complex and intraflagellar proteins. The adaptor proteins to recruit the heterotrimeric kinesin-2 to its specific cargoes are not identified, and hence, not much is known about the mechanism for its cargo recognition and binding. The 14-3-3 family proteins form homo and heterodimers and bind to several types of receptors and protein kinases/phosphates to bring together a multiprotein complex regulating cell signalling. In this study, we show that one of the 14-3-3 isoforms,14-3-3{varepsilon}, can bind to KIF3B in vitro. We mapped the 14-3-3{varepsilon} binding site on the C-terminal tail domain of KIF3B with the help of acceptor photobleaching-Foster Resonance Energy Transfer and split-APEX2 assays. With this evidence, we propose for the first time that 14-3-3{varepsilon} can be a potential adaptor for kinesin-2.

cell biology↗

bioRxiv2020

Deubiquitinase UCHL1 Maintains Protein Homeostasis through PSMA7-APEH-Proteasome Axis in High-Grade Serous Ovarian Carcinoma

High-grade serous ovarian cancer (HGSOC) is characterized by chromosomal instability, DNA damage, oxidative stress, and high metabolic demand, which exacerbate misfolded, unfolded and damaged protein burden resulting in increased proteotoxicity. However, the underlying mechanisms that maintain protein homeostasis to promote HGSOC growth remain poorly understood. In this study, we report that the neuronal deubiquitinating enzyme, ubiquitin carboxyl-terminal hydrolase L1 (UCHL1) is overexpressed in HGSOC and maintains protein homeostasis. UCHL1 expression was markedly increased in HGSOC patient tumors and serous tubal intraepithelial carcinoma (HGSOC precursor lesions). High UCHL1 levels correlated with higher tumor grade and poor patient survival. UCHL1 inhibition reduced HGSOC cell proliferation and invasion through the outer layers of omentum as well as significantly decreased the in vivo metastatic tumor growth in ovarian cancer xenografts. Transcriptional profiling of UCHL1 silenced HGSOC cells revealed the down-regulation of genes implicated with proteasome activity along with the upregulation of endoplasmic reticulum (ER) stress-induced genes. Reduced expression of proteasome subunit alpha 7 (PSMA7) and acylaminoacyl peptide hydrolase (APEH) resulted in a significant decrease in proteasome activity, impaired protein degradation, and abrogated HGSOC growth. Furthermore, the accumulation of polyubiquitinated proteins in the UCHL1 silenced cells led to attenuation of mTORC1 activity and protein synthesis, and induction of terminal unfolded protein response. Collectively, these results indicate that UCHL1 promotes HGSOC growth by mediating protein homeostasis through the PSMA7-APEH-proteasome axis. O_FIG O_LINKSMALLFIG WIDTH=183 HEIGHT=200 SRC="FIGDIR/small/316810v2_ufig1.gif" ALT="Figure 1"> View larger version (71K): org.highwire.dtl.DTLVardef@d38d5borg.highwire.dtl.DTLVardef@e58513org.highwire.dtl.DTLVardef@83e274org.highwire.dtl.DTLVardef@884ec3_HPS_FORMAT_FIGEXP M_FIG C_FIG ImplicationsThis study identifies the novel links in the proteostasis network to target protein homeostasis in HGSOC. It recognizes the potential of inhibiting UCHL1 and APEH to sensitize cancer cells to proteotoxic stress and as novel alternative therapeutic approaches.

cancer biology↗