RESUMEN
Clear cell renal cell carcinoma (ccRCC) is characterized by the loss of tumor suppressor Von Hippel Lindau (VHL) function. VHL is the component of an E3 ligase complex that promotes the ubiquitination and degradation of hypoxia inducible factor α (HIF-α) (including HIF1α and HIF2α) and Zinc Fingers And Homeoboxes 2 (ZHX2). Our recent research showed that ZHX2 contributed to ccRCC tumorigenesis in a HIF-independent manner. However, it is still unknown whether ZHX2 could be modified through deubiquitination even in the absence of pVHL. Here, we performed a deubiquitinase (DUB) complementary DNA (cDNA) library binding screen and identified USP13 as a DUB that bound ZHX2 and promoted ZHX2 deubiquitination. As a result, USP13 promoted ZHX2 protein stability in an enzymatically dependent manner, and depletion of USP13 led to ZHX2 down-regulation in ccRCC. Functionally, USP13 depletion led to decreased cell proliferation measured by two-dimensional (2D) colony formation and three-dimensional (3D) anchorage-independent growth. Furthermore, USP13 was essential for ccRCC tumor growth in vivo, and the effect was partially mediated by its regulation on ZHX2. Our findings support that USP13 may be a key effector in ccRCC tumorigenesis.
Asunto(s)
Carcinoma de Células Renales , Proteínas de Homeodominio , Neoplasias Renales , Factores de Transcripción , Proteasas Ubiquitina-Específicas , Carcinogénesis/genética , Carcinoma de Células Renales/patología , Línea Celular Tumoral , Regulación Neoplásica de la Expresión Génica , Proteínas de Homeodominio/genética , Proteínas de Homeodominio/metabolismo , Humanos , Subunidad alfa del Factor 1 Inducible por Hipoxia/metabolismo , Neoplasias Renales/patología , Factores de Transcripción/genética , Factores de Transcripción/metabolismo , Proteasas Ubiquitina-Específicas/genética , Proteasas Ubiquitina-Específicas/metabolismo , Proteína Supresora de Tumores del Síndrome de Von Hippel-Lindau/genética , Proteína Supresora de Tumores del Síndrome de Von Hippel-Lindau/metabolismoRESUMEN
Nitrogen source sensing, uptake, and assimilation are central for growth and development of microorganisms which requires the participation of a global control of nitrogen metabolism-associated genes at the transcriptional level. In soil-dwelling antibiotic-producing actinomycetes, this role is played by GlnR, an OmpR family regulator. In this work, we demonstrate that SACE_7101 is the ortholog of actinomycetes' GlnR global regulators in the erythromycin producer Saccharopolyspora erythraea. Indeed, the chromosomal deletion of SACE_7101 severely affects the viability of S. erythraea when inoculated in minimal media supplemented with NaNO3, NaNO2, NH4Cl, glutamine, or glutamate as sole nitrogen source. Combination of in silico prediction of cis-acting elements, subsequent in vitro (through gel shift assays) and in vivo (real-time reverse transcription polymerase chain reaction) validations of the predicted target genes revealed a very large GlnR regulon aimed at adapting the nitrogen metabolism of S. erythraea. Indeed, enzymes/proteins involved in (i) uptake and assimilation of ammonium, (ii) transport and utilization of urea, (iii) nitrite/nitrate, (iv) glutamate/glutamine, (v) arginine metabolism, (vi) nitric oxide biosynthesis, and (vii) signal transduction associated with the nitrogen source supplied have at least one paralog gene which expression is controlled by GlnR. Our work highlights a GlnR-binding site consensus sequence (t/gna/cAC-n6-GaAAc) which is similar although not identical to the consensus sequences proposed for other actinomycetes. Finally, we discuss the distinct and common features of the GlnR-mediated transcriptional control of nitrogen metabolism between S. erythraea and the model organism Streptomyces coelicolor.