Identification of a c.544C>T mutation in WDR34 as a deleterious recessive allele of short rib-polydactyly syndrome

WDR34, a candidate gene for non-syndromic rod-cone dystrophy

Rod-cone dystrophy (RCD), also called retinitis pigmentosa, is characterized by rod followed by cone photoreceptor degeneration, leading to gradual visual loss. Mutations in over 65 genes have been associated with non-syndromic RCD explaining 60% to 70% of cases, with novel gene defects possibly accounting for the unsolved cases. Homozygosity mapping and whole-exome sequencing applied to a case of autosomal recessive non-syndromic RCD from a consanguineous union identified a homozygous variant in WDR34. Mutations in WDR34 have been previously associated with severe ciliopathy syndromes possibly associated with a retinal dystrophy. This is the first report of a homozygous mutation in WDR34 associated with non-syndromic RCD.

High WDR34 mRNA expression as a potential prognostic biomarker in patients with breast cancer as determined by integrated bioinformatics analysis

The WD-repeat domain (WDR) family is distributed in the majority of eukaryotes and has several unique biological functions. It serves important roles in signal transduction, cytoskeleton assembly, protein transport, RNA processing, chromatin modification and transcription mechanisms. WD repeat domain 34 (WDR34) has been recently identified as a member of the WDR family. Overexpression of WDR34 was accompanied by the presence of multiple centrioles in the cell, suggesting that it was associated with tumor occurrence. However, its association with breast cancer was unclear. To the best of our knowledge, it has not yet been confirmed whether WDR34 gene expression is associated with breast cancer. Therefore, the current study attempted to clarify this by performing a comprehensive study using multiple datasets in the Oncomine, Breast Cancer Gene-Expression Miner and Kaplan-Meier Plotter databases. The analysis indicated that the mRNA expression levels of WDR34 were increased in breast cancer tissues compared with normal tissues. Consistent with this result, the Broad-Novartis Cancer Cell Line Encyclopedia revealed that WDR34 mRNA expression levels were upregulated in breast cancer cell lines compared with other cancer cells. It was noted that high WDR34 mRNA expression was associated with forkhead box M1 and PTTG1 regulator of sister chromatid separation, securing in co-expression analysis. Expression profile characteristics of WDR34 mRNA were identified in different molecular subtypes of breast cancer. Furthermore, survival analysis revealed that increased expression levels of WDR34 mRNA were associated with poor overall survival in patients with breast cancer, particularly in luminal B, lymph node status-positive and estrogen receptor (ER)-negative subgroups. Additionally, Kaplan-Meier curves revealed that high WDR34 mRNA expression was associated with shorter relapse-free survival in patients with breast cancer, particularly in ER-positive, human epidermal growth factor receptor 2-negative and progesterone receptor-positive subgroups. These results suggested that WDR34 may be used as a prognosis predictor in breast cancer and may provide a novel target for the diagnosis and treatment of breast cancer.

Interactions of the dynein-2 intermediate chain WDR34 with the light chains are required for ciliary retrograde protein trafficking

The dynein-2 complex drives retrograde ciliary protein trafficking by associating with the intraflagellar transport (IFT) machinery, containing IFT-A and IFT-B complexes. We recently showed that the dynein-2 complex, which comprises 11 subunits, can be divided into three subcomplexes: DYNC2H1-DYNC2LI1, WDR34-DYNLL1/DYNLL2-DYNLRB1/DYNLRB2, and WDR60-TCTEX1D2-DYNLT1/DYNLT3. In this study, we demonstrated that the WDR34 intermediate chain interacts with the two light chains, DYNLL1/DYNLL2 and DYNLRB1/DYNLRB2, via its distinct sites. Phenotypic analyses of WDR34-knockout cells exogenously expressing various WDR34 constructs showed that the interactions of the WDR34 intermediate chain with the light chains are crucial for ciliary retrograde protein trafficking. Furthermore, we found that expression of the WDR34 N-terminal construct encompassing the light chain-binding sites but lacking the WD40 repeat domain inhibits ciliary biogenesis and retrograde trafficking in a dominant-negative manner, probably by sequestering WDR60 or the light chains. Taken together with phenotypic differences of several WDR34-knockout cell lines, these results indicate that incorporation of DYNLL1/DYNLL2 and DYNLRB1/DYNLRB2 into the dynein-2 complex via interactions with the WDR34 intermediate chain is crucial for dynein-2 function in retrograde ciliary protein trafficking.