title: Phosphorylation-dependent cleavage regulates von Hippel Lindau proteostasis and function.
abstract: Loss of von Hippel Lindau (VHL) protein function is a key driver of VHL diseases, including sporadic and inherited clear cell renal cell carcinoma. Modulation of the proteostasis of VHL, especially missense point-mutated VHL, is a promising approach to augmenting VHL levels and function. VHL proteostasis is regulated by multiple mechanisms including folding, chaperone binding, complex formation and phosphorylation. Nevertheless, many details underlying the regulations of VHL proteostasis are unknown. VHL is expressed as two variants, VHL30 and VHL19. Furthermore, the long-form variant of VHL was often detected as multiple bands by western blotting. However, how these multiple species of VHL are generated and whether the process regulates VHL proteostasis and function are unknown. We hypothesized that the two major species are generated by VHL protein cleavage, and the cleavage regulates VHL proteostasis and subsequent function. We characterized VHL species using genetical and pharmacological approaches and showed that VHL was first cleaved at the N-terminus by chymotrypsin C before being directed for proteasomal degradation. Casein kinase 2-mediated phosphorylation at VHL N-terminus was required for the cleavage. Furthermore, inhibition of cleavage stabilized VHL protein and thereby promoted HIF downregulation. Our study reveals a novel mechanism regulating VHL proteostasis and function, which is significant for identifying new drug targets and developing new therapeutic approaches targeting VHL deficiency in VHL diseases.
authors.affiliation: Department of Genitourinary Medical Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX, USA.
authors.forename: P
authors.initials: P
authors.lastname: German
authors.affiliation: Department of Genitourinary Medical Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX, USA.
authors.forename: S
authors.initials: S
authors.lastname: Bai
authors.affiliation: Department of Genitourinary Medical Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX, USA.
authors.forename: X-D
authors.initials: XD
authors.lastname: Liu
authors.affiliation: Department of Genitourinary Medical Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX, USA.
authors.forename: M
authors.initials: M
authors.lastname: Sun
authors.affiliation: Department of Genitourinary Medical Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX, USA.
authors.forename: L
authors.initials: L
authors.lastname: Zhou
authors.affiliation: Department of Genitourinary Medical Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX, USA.
authors.forename: S
authors.initials: S
authors.lastname: Kalra
authors.affiliation: Department of Genitourinary Medical Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX, USA.
authors.forename: X
authors.initials: X
authors.lastname: Zhang
authors.affiliation: Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA.
authors.forename: R
authors.initials: R
authors.lastname: Minelli
authors.affiliation: Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA.
authors.forename: K L
authors.initials: KL
authors.lastname: Scott
authors.affiliation: Department of Systems Biology, The University of Texas MD Anderson Cancer Center, Houston, TX, USA.
authors.forename: G B
authors.initials: GB
authors.lastname: Mills
authors.affiliation: Department of Genitourinary Medical Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX, USA.
authors.forename: E
authors.initials: E
authors.lastname: Jonasch
authors.affiliation: Department of Systems Biology, The University of Texas MD Anderson Cancer Center, Houston, TX, USA.
authors.forename: Z
authors.initials: Z
authors.lastname: Ding
mesh_terms: D002292:Carcinoma, Renal Cell / Q000235:genetics* / Q000473:pathology; D047390:Casein Kinase II / Q000235:genetics / Q000378:metabolism; D045744:Cell Line, Tumor; D002918:Chymotrypsin / Q000737:chemistry; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D009154:Mutation; D010766:Phosphorylation; D011485:Protein Binding; D020033:Protein Isoforms / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D059748:Proteolysis; D051794:Von Hippel-Lindau Tumor Suppressor Protein / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D006623:von Hippel-Lindau Disease / Q000235:genetics* / Q000473:pathology
chemical_list: D020033:Protein Isoforms; D051794:Von Hippel-Lindau Tumor Suppressor Protein; D047390:Casein Kinase II; D002918:Chymotrypsin; C117569:chymotrypsin C