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Protein ubiquitination plays a pivotal role in protein homeostasis. Ubiquitination may regulate the stability, activity, protein–protein interaction, and localization of a protein. Ubiquitination is subject to regulation by two groups of counteracting enzymes, the E3 ubiquitin ligases and deubiquitinases. Consistently, deubiquitinases are involved in essentially all biological processes. OTUB1, an OTU-family deubiquitinase, is a critical regulator of development, cancer, DNA damage response, and immune response. OTUB1 antagonizes the ubiquitination of a wide-spectrum of proteins through at least two different mechanisms. Besides direct deubiquitination, OTUB1 can also inhibit ubiquitination by non-canonically blocking ubiquitin transfer from certain ubiquitin-conjugases (E2). In this review, we start with a general background of protein ubiquitination and deubiquitination. Next, we introduce the basic characteristics of OTUB1 and then elaborate on the updated biological functions of OTUB1. Afterwards, we discuss potential mechanisms underlying the versatility and specificity of OTUB1 functions. In the end, we discuss the perspective that OTUB1 can be a potential therapeutic target for cancer.

Type VI CRISPR effector Cas13d from Ruminococcus flavefaciens XPD3002 (RfxCas13d) is an RNA-guided RNA endonuclease. RfxCas13d has been harnessed to knockdown gene expression with high specificity in various systems including mammalian cells. While inducible knockdown is advantageous over constitutive knockdown in many scenarios, current inducible systems of RfxCas13d express CRISPR RNA and Cas13d separately. Such systems could be cumbersome to handle and may hamper the application of RfxCas13d in some scenarios. Here, we design an all-in-one Cas13d lentivirus vector which renders efficient and inducible knockdown in a doxycycline dosage-dependent manner. Furthermore, we find that Cas13d has a short half-life in mammalian cells. As a result, knockdown can be promptly reversed after doxycycline withdrawal. This vector is particularly useful for applications involving indispensable genes and/or in cells hard to transduce.