**Targeting E3 Ubiquitin Ligases and Deubiquitinases in Ciliopathy and Cancer**

### **Takashi Shiromizu 1, Mizuki Yuge 1, Kousuke Kasahara 2, Daishi Yamakawa 2, Takaaki Matsui 3, Yasumasa Bessho 3, Masaki Inagaki 2 and Yuhei Nishimura 1,\***


Received: 31 July 2020; Accepted: 17 August 2020; Published: 19 August 2020

**Abstract:** Cilia are antenna-like structures present in many vertebrate cells. These organelles detect extracellular cues, transduce signals into the cell, and play an essential role in ensuring correct cell proliferation, migration, and differentiation in a spatiotemporal manner. Not surprisingly, dysregulation of cilia can cause various diseases, including cancer and ciliopathies, which are complex disorders caused by mutations in genes regulating ciliary function. The structure and function of cilia are dynamically regulated through various mechanisms, among which E3 ubiquitin ligases and deubiquitinases play crucial roles. These enzymes regulate the degradation and stabilization of ciliary proteins through the ubiquitin–proteasome system. In this review, we briefly highlight the role of cilia in ciliopathy and cancer; describe the roles of E3 ubiquitin ligases and deubiquitinases in ciliogenesis, ciliopathy, and cancer; and highlight some of the E3 ubiquitin ligases and deubiquitinases that are potential therapeutic targets for these disorders.

**Keywords:** ubiquitin–proteasome pathway; cilia; ciliogenesis; differentiation; proliferation; ciliopathy; cancer
