The Molecular Chaperone TRiC/CCT Binds to the Trp-Asp 40 (WD40) Repeat Protein WDR68 and Promotes Its Folding, Protein Kinase DYRK1A Binding, and Nuclear Accumulation

Abstract

Background: Trp-Asp (WD) repeat protein 68 (WDR68) is a binding partner of dual specificity tyrosine phosphorylationregulated protein kinase (DYRK1A), a kinase partly responsible for aspects of Down syndrome. Results: The molecular chaperone T-complex protein 1 (TCP1) ring complex/chaperonin-containing TCP1 (TRiC/CCT) binds to WDR68 and modulates its structure, DYRK1A-binding, and cellular localization. Conclusion: TRiC/CCT is essential for correct folding and function of WDR68. Significance: TRiC/CCT may have a general role in forming the functional WD40 repeat seven-bladed ␤-propeller structure.

Biochemical Reduction of the Topology of the Diverse WDR76 Protein Interactome

“…For example, the CCT complex associates with the C-terminal WD40 domain of WDR76. The CCT complex has been previously shown to promote folding of the WD40 repeat domain (Miyata et al, 2014). Surprisingly our studies show that WDR76 interacts with CCT via the WD40 domain suggesting that CCT may be important for folding of the WD40 repeat domain in WDR76.…”

The Mechanism and Function of Group II Chaperonins

“…This difficulty is compounded by the fact that each subunit in the chaperonin recognizes diverse sequence determinants. While some motifs are frequently found in proteins that interact with TRiC, such as the WD40 β-propellers [89, 90], they cannot be said to be clear identifiers. Consistent with the notion that there is no one feature that dictates chaperonin requirement, studies carried out in in vitro translation systems predict that approximately 10% of all cytosolic proteins transit through the TRiC complex [28].…”

A proteomic approach to understand MMP‐3‐driven developmental processes in the postnatal cerebellum: Chaperonin CCT6A and MAP kinase as contributing factors

“…As spot 6 and 16 show a shift in pI, but also a small shift in molecular weight (Fig. ), we hypothesized that CCT6a might exist in different isoforms, as recently described (Mukherjee et al, ), or/and that CCT6a might be subjected to a PTM, although the type of PTM remaining elusive (Li et al, ; Xiang et al, ; Dun et al, ; Miyata et al, ). In addition, CCT6a in spot 6 shows a higher expression in WT samples, while CCT6a in spot 16 is more abundantly present in MMP‐3 −/− cerebella (Fig.…”

“…An impaired activation of the ERK1/2 signaling pathway, that implies reduced phosphorylation of the ERKs, is known to cause neurodevelopmental and behavioral deficits (Davis and Laroche, ; Chirivi et al, ; Lefloch et al, ; Samuels et al, ; Nuttall and Oteiza, ; Pucilowska et al, ). CCT6a has been identified as a phosphoprotein and is known to contain ERK binding sites, but it is not clear yet whether CCT6a is also phosphorylated by ERK (Xiang et al, ; Oppermann et al, ; Miyata et al, ). Western blotting for phosphorylated, and thus activated ERK1 and ERK2, revealed a clearly stronger expression of pERK2 in comparison to pERK1 in WT cerebellar samples [Fig.…”

“…CCT6a has also been identified as a phosphoprotein in adult rat ventricular myocytes subjected to diazoxide preconditioning (Li et al, ). Recently, a phospho‐proteomic approach unveiled in vivo phosphorylation sites on CCT subunits, including CCT6a, more specifically, on serine and threonine residues (Miyata et al, ). CCT6a has also been described to possess phosphorylation sites for MAPK/ERK, yet it is still unclear whether PTMs such as phosphorylation are necessary for this subunit to be activated (Xiang et al, ; Roskoski, ).…”