RNF6

RNF6 Full Name

ring finger protein (C3H2C3 type) 6

RNF6 Introduction

RNF6 encodes a C3H2C3-type RING finger E3 ubiquitin ligase that has emerged as a key modifier of androgen receptor (AR) action. The RING domain recruits an E2 ubiquitin-conjugating enzyme to catalyze isopeptide linkage of ubiquitin chains onto substrate lysines, a reversible mark that can either target a protein for proteasomal destruction or, through non-degradative K63 linkages, alter its trafficking and cofactor interactions without changing protein abundance. Identified in a proteomic screen as an AR-associated protein, RNF6 catalyzes site-specific polyubiquitination of AR and thereby enhances AR transcriptional activity. Rather than simply degrading the receptor, RNF6-mediated ubiquitination remodels cofactor recruitment: knockdown of RNF6 or mutation of the ubiquitin-acceptor sites on AR selectively alters a subset of AR target genes and diminishes AR and coactivator loading at androgen-responsive elements. This mechanism explains how a single post-translational modification can sharpen the specificity of a master transcriptional program rather than merely switching it on or off.

Figure 1. A Postulated Model of Regulation of AR Activity by RNF6. (Source: Xu K, et al. 2009)

The pathological relevance of RNF6 is most clearly documented in prostate cancer, where RNF6 is overexpressed in hormone-refractory tumors and is required for cancer cell growth under androgen-depleted conditions, implicating it in castration resistance. Beyond the prostate, RNF6 regulates AR signaling in the ovary, where androgen-induced RNF6 expression promotes K63-linked AR ubiquitination and soluble Kit-ligand production, driving granulosa cell proliferation and follicle growth. Additional studies place RNF6 in neuronal development, where it controls local LIM kinase 1 levels in axonal growth cones, and in cancer genomics, where somatic RNF6 mutations have been catalogued in esophageal squamous cell carcinoma. Together these findings portray RNF6 as a versatile ubiquitin ligase whose substrate spectrum spans transcriptional regulators, cytoskeletal modulators, and oncogenic drivers. RNF6 thus illustrates a recurring theme in ubiquitin biology: the same ligase can edit substrate fate in opposing directions depending on the linkage it installs, so that context-specific readouts are essential to interpret its true biological role.

Alternate Names for RNF6

RNF6; ring finger protein (C3H2C3 type) 6; E3 ubiquitin-protein ligase RNF6; DKFZp686P0776; RING H2 protein RNF 6; RING-H2 protein RNF-6;

• 1. Xu K, et al. Regulation of androgen receptor transcriptional activity and specificity by RNF6-induced ubiquitination. Cancer Cell. 2009 Apr 7;15(4):270-82.
  2. Tursun B, et al. The ubiquitin ligase Rnf6 regulates local LIM kinase 1 levels in axonal growth cones. Genes Dev. 2005 Oct 1;19(19):2307-19.