SCFFbxw5 targets kinesin-13 proteins to facilitate ciliogenesis

KIF2C/MCAK a prognostic biomarker and its oncogenic potential in malignant progression, and prognosis of cancer patients: a systematic review and meta-analysis as biomarker

KIF2C/MCAK (KIF2C) is the most well-characterized member of the kinesin-13 family, which is critical in the regulation of microtubule (MT) dynamics during mitosis, as well as interphase. This systematic review briefly describes the important structural elements of KIF2C, its regulation by multiple molecular mechanisms, and its broad cellular functions. Furthermore, it systematically summarizes its oncogenic potential in malignant progression and performs a meta-analysis of its prognostic value in cancer patients. KIF2C was shown to be involved in multiple crucial cellular processes including cell migration and invasion, DNA repair, senescence induction and immune modulation, which are all known to be critical during the development of malignant tumors. Indeed, an increasing number of publications indicate that KIF2C is aberrantly expressed in multiple cancer entities. Consequently, we have highlighted its involvement in at least five hallmarks of cancer, namely: genome instability, resisting cell death, activating invasion and metastasis, avoiding immune destruction and cellular senescence. This was followed by a systematic search of KIF2C/MCAK's expression in various malignant tumor entities and its correlation with clinicopathologic features. Available data were pooled into multiple weighted meta-analyses for the correlation between KIF2Chigh protein or gene expression and the overall survival in breast cancer, non-small cell lung cancer and hepatocellular carcinoma patients. Furthermore, high expression of KIF2C was correlated to disease-free survival of hepatocellular carcinoma. All meta-analyses showed poor prognosis for cancer patients with KIF2Chigh expression, associated with a decreased overall survival and reduced disease-free survival, indicating KIF2C's oncogenic potential in malignant progression and as a prognostic marker. This work delineated the promising research perspective of KIF2C with modern in vivo and in vitro technologies to further decipher the function of KIF2C in malignant tumor development and progression. This might help to establish KIF2C as a biomarker for the diagnosis or evaluation of at least three cancer entities.

KIF2C promotes clear cell renal cell carcinoma progression via activating JAK2/STAT3 signaling pathway

BACKGROUND

Clear cell renal cell carcinoma (ccRCC) is one of the most common malignant tumors that can be highly aggressive. Despite advances in the exploration of its underlying molecular biology, the clinical outcome for advanced ccRCC is still unsatisfied. Recently, more attention was paid to the functions of Kinesin family member 2C (KIF2C) in cancer progression, while the specific function of KIF2C in ccRCC has not been sufficiently elucidated. The present study aims to investigate the role of KIF2C in the progression of ccRCC and reveal potential mechanisms.

METHODS

Expression of KIF2C in ccRCC tissues and adjacent normal tissue was compared and the association of KIF2C expression level with tumor grade, stage, and metastasis were analyzed using online web tool. Kaplan-Meier survival was performed to detect the association of KIF2C expression and patient' prognosis. Stably cell lines with KIF2C knockdown or overexpression were constructed by lentivirus infection. CCK-8, colony formation, scratch healing, and transwell invasion assays were carried out to explore the effect of KIF2C knockdown or overexpression on the proliferation, migration, and invasion of ccRCC cells. Gene set enrichment analysis (GSEA) was conducted to reveal signaling pathways associated with KIF2C expression. The effect of KIF2C on JAK2/STAT3 signaling pathway were explored by western blot assay.

RESULTS

KIF2C expression was significantly upregulated in ccRCC tissues and was higher with the increase of tumor grade, stage, and metastasis. Higher expression of KIF2C was correlated with worse overall survival and diseases free survival in ccRCC patients. Silence of KIF2C inhibited proliferation, migration, and invasion in ccRCC cells. Conversely, overexpression of KIF2C had the opposite effect. GSEA results showed that JAK/STAT signaling pathway was markedly enriched in KIF2Chigh group. Pearson' correlation revealed that KIF2C expression was significantly associated with genes in JAK2/STAT3 signaling. Western blot results showed that KIF2C knockdown decreased protein expression of p-JAK2 and p-STAT3, and KIF2C overexpression increased the phosphorylation of JAK2 and STAT3. AG490, a JAK2/STAT3 signaling inhibitor, could partly impair the tumor-promoting effects of KIF2C in ccRCC.

CONCLUSION

KIF2C expression was significantly upregulated in ccRCC and correlated with tumor grade, stage, metastasis, and patients' prognosis. KIF2C promoted ccRCC progression via activating JAK2/STAT3 signaling pathway, and KIF2C might be a novel target in ccRCC therapy.

Function, mechanism and drug discovery of ubiquitin and ubiquitin-like modification with multiomics profiling for cancer therapy

Ubiquitin (Ub) and ubiquitin-like (Ubl) pathways are critical post-translational modifications that determine whether functional proteins are degraded or activated/inactivated. To date, >600 associated enzymes have been reported that comprise a hierarchical task network (e.g., E1-E2-E3 cascade enzymatic reaction and deubiquitination) to modulate substrates, including enormous oncoproteins and tumor-suppressive proteins. Several strategies, such as classical biochemical approaches, multiomics, and clinical sample analysis, were combined to elucidate the functional relations between these enzymes and tumors. In this regard, the fundamental advances and follow-on drug discoveries have been crucial in providing vital information concerning contemporary translational efforts to tailor individualized treatment by targeting Ub and Ubl pathways. Correspondingly, emphasizing the current progress of Ub-related pathways as therapeutic targets in cancer is deemed essential. In the present review, we summarize and discuss the functions, clinical significance, and regulatory mechanisms of Ub and Ubl pathways in tumorigenesis as well as the current progress of small-molecular drug discovery. In particular, multiomics analyses were integrated to delineate the complexity of Ub and Ubl modifications for cancer therapy. The present review will provide a focused and up-to-date overview for the researchers to pursue further studies regarding the Ub and Ubl pathways targeted anticancer strategies.

Influenza virus reduces ubiquitin E3 ligase MARCH10 expression to decrease ciliary beat frequency

Respiratory viruses, such as influenza, decrease airway cilia function and expression, which leads to reduced mucociliary clearance and inhibited overall immune defense. Ubiquitination is a posttranslational modification using E3 ligases, which plays a role in the assembly and disassembly of cilia. We examined the role of membrane-associated RING-CH (MARCH) family of E3 ligases during influenza infection and determined that MARCH10, specifically expressed in ciliated epithelial cells, is significantly decreased during influenza infection in mice, human lung epithelial cells, and human lung tissue. Cellular depletion of MARCH10 in differentiated human bronchial epithelial cells (HBECs) using CRISPR/Cas9 showed a decrease in ciliary beat frequency. Furthermore, MARCH10 cellular knockdown in combination with influenza infection selectively decreased immunoreactive levels of the ciliary component, dynein axonemal intermediate chain 1. Cellular overexpression of MARCH10 significantly decreased influenza hemagglutinin protein levels in the differentiated HBECs and knockdown of MARCH10 increased IL-1β cytokine expression, whereas overexpression had the reciprocal effect. These findings suggest that MARCH10 may have a protective role in airway pulmonary host defense and innate immunity during influenza infection.

The SCF-FBXW7 E3 ubiquitin ligase triggers degradation of histone 3 lysine 4 methyltransferase complex component WDR5 to prevent mitotic slippage

During prolonged mitotic arrest induced by antimicrotubule drugs, cell fate decision is determined by two alternative pathways, one leading to cell death and the other inducing premature escape from mitosis by mitotic slippage. FBWX7, a member of the F-box family of proteins and substrate-targeting subunit of the SKP1-CUL1-F-Box E3 ubiquitin ligase complex, promotes mitotic cell death and prevents mitotic slippage, but molecular details underlying these roles for FBWX7 are unclear. In this study, we report that WDR5 (WD-repeat containing protein 5), a component of the mixed lineage leukemia complex of histone 3 lysine 4 methyltransferases, is a substrate of FBXW7. We determined by coimmunoprecipitation experiments and in vitro binding assays that WDR5 interacts with FBXW7 in vivo and in vitro. SKP1-CUL1-F-Box-FBXW7 mediates ubiquitination of WDR5 and targets it for proteasomal degradation. Furthermore, we find that WDR5 depletion counteracts FBXW7 loss of function by reducing mitotic slippage and polyploidization. In conclusion, our data elucidate a new mechanism in mitotic cell fate regulation, which might contribute to prevent chemotherapy resistance in patients after antimicrotubule drug treatment.

Regulation of Host-Pathogen Interactions via the Ubiquitin System

Ubiquitination is a posttranslational modification that regulates a multitude of cellular functions. Pathogens, such as bacteria and viruses, have evolved sophisticated mechanisms that evade or counteract ubiquitin-dependent host responses, or even exploit the ubiquitin system to their own advantage. This is largely done by numerous pathogen virulence factors that encode E3 ligases and deubiquitinases, which are often used as weapons in pathogen-host cell interactions. Moreover, upon pathogen attack, host cellular signaling networks undergo major ubiquitin-dependent changes to protect the host cell, including coordination of innate immunity, remodeling of cellular organelles, reorganization of the cytoskeleton, and reprogramming of metabolic pathways to restrict growth of the pathogen. Here we provide mechanistic insights into ubiquitin regulation of host-pathogen interactions and how it affects bacterial and viral pathogenesis and the organization and response of the host cell.

Proteolytic control in ciliogenesis: Temporal restriction or early initiation?

Cellular processes are highly dependent on a dynamic proteome that undergoes structural and functional rearrangements to allow swift conversion between different cellular states. By inducing proteasomal degradation of inhibitory or stimulating factors, ubiquitylation is particularly well suited to trigger such transitions. One prominent example is the remodelling of the centrosome upon cell cycle exit, which is required for the formation of primary cilia - antenna-like structures on the surface of most cells that act as integrative hubs for various extracellular signals. Over the last decade, many reports on ubiquitin-related events involved in the regulation of ciliogenesis have emerged. Very often, these processes are considered to be initiated ad hoc, that is, directly before its effect on cilia biogenesis becomes evident. While such a temporal restriction may hold true for the majority of events, there is evidence that some of them are initiated earlier during the cell cycle. Here, we provide an overview of ubiquitin-dependent processes in ciliogenesis and discuss available data that indicate such an early onset of proteolytic regulation within preceding cell cycle stages.

Pathophysiology of Primary Cilia: Signaling and Proteostasis Regulation

Primary cilia are microtubule-based, non-motile sensory organelles present in most types of growth-arrested eukaryotic cells. They are transduction hubs that receive and transmit external signals to the cells in order to control growth, differentiation and development. Mutations of genes involved in the formation, maintenance or disassembly of ciliary structures cause a wide array of developmental genetic disorders, also known as ciliopathies. The primary cilium is formed during G1 in the cell cycle and disassembles at the G2/M transition. Following the completion of the cell division, the cilium reassembles in G1. This cycle is finely regulated at multiple levels. The ubiquitin-proteasome system (UPS) and the autophagy machinery, two main protein degradative systems in cells, play a fundamental role in cilium dynamics. Evidence indicate that UPS, autophagy and signaling pathways may act in synergy to control the ciliary homeostasis. However, the mechanisms involved and the links between these regulatory systems and cilium biogenesis, dynamics and signaling are not well defined yet. Here, we discuss the reciprocal regulation of signaling pathways and proteolytic machineries in the control of the assembly and disassembly of the primary cilium, and the impact of the derangement of these regulatory networks in human ciliopathies.