title: Proteomic analysis of pRb loss highlights a signature of decreased mitochondrial oxidative phosphorylation.
abstract: The retinoblastoma tumor suppressor (pRb) protein associates with chromatin and regulates gene expression. Numerous studies have identified Rb-dependent RNA signatures, but the proteomic effects of Rb loss are largely unexplored. We acutely ablated Rb in adult mice and conducted a quantitative analysis of RNA and proteomic changes in the colon and lungs, where Rb(KO) was sufficient or insufficient to induce ectopic proliferation, respectively. As expected, Rb(KO) caused similar increases in classic pRb/E2F-regulated transcripts in both tissues, but, unexpectedly, their protein products increased only in the colon, consistent with its increased proliferative index. Thus, these protein changes induced by Rb loss are coupled with proliferation but uncoupled from transcription. The proteomic changes in common between Rb(KO) tissues showed a striking decrease in proteins with mitochondrial functions. Accordingly, RB1 inactivation in human cells decreased both mitochondrial mass and oxidative phosphorylation (OXPHOS) function. RB(KO) cells showed decreased mitochondrial respiratory capacity and the accumulation of hypopolarized mitochondria. Additionally, RB/Rb loss altered mitochondrial pyruvate oxidation from (13)C-glucose through the TCA cycle in mouse tissues and cultured cells. Consequently, RB(KO) cells have an enhanced sensitivity to mitochondrial stress conditions. In summary, proteomic analyses provide a new perspective on Rb/RB1 mutation, highlighting the importance of pRb for mitochondrial function and suggesting vulnerabilities for treatment.
authors: Massachusetts General Hospital Cancer Center, Harvard Medical School, Charlestown, Massachusetts 02129, USA;
authors: Brandon N
authors: BN
authors: Nicolay
authors: David H. Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA;
authors: Paul S
authors: PS
authors: Danielian
authors: Massachusetts General Hospital Cancer Center, Harvard Medical School, Charlestown, Massachusetts 02129, USA;
authors: Filippos
authors: F
authors: Kottakis
authors: Massachusetts General Hospital Cancer Center, Harvard Medical School, Charlestown, Massachusetts 02129, USA;
authors: John D
authors: JD
authors: Lapek
authors: Massachusetts General Hospital Cancer Center, Harvard Medical School, Charlestown, Massachusetts 02129, USA;
authors: Ioannis
authors: I
authors: Sanidas
authors: Massachusetts General Hospital Cancer Center, Harvard Medical School, Charlestown, Massachusetts 02129, USA;
authors: Wayne O
authors: WO
authors: Miles
authors: Massachusetts General Hospital Cancer Center, Harvard Medical School, Charlestown, Massachusetts 02129, USA; University Medical Center Utrecht, Utrecht 3584CX, Netherlands.
authors: Mantre
authors: M
authors: Dehnad
authors: Massachusetts General Hospital Cancer Center, Harvard Medical School, Charlestown, Massachusetts 02129, USA;
authors: Katrin
authors: K
authors: Tschöp
authors: Massachusetts General Hospital Cancer Center, Harvard Medical School, Charlestown, Massachusetts 02129, USA;
authors: Jessica J
authors: JJ
authors: Gierut
authors: Massachusetts General Hospital Cancer Center, Harvard Medical School, Charlestown, Massachusetts 02129, USA;
authors: Amity L
authors: AL
authors: Manning
authors: Massachusetts General Hospital Cancer Center, Harvard Medical School, Charlestown, Massachusetts 02129, USA;
authors: Robert
authors: R
authors: Morris
authors: Massachusetts General Hospital Cancer Center, Harvard Medical School, Charlestown, Massachusetts 02129, USA;
authors: Kevin
authors: K
authors: Haigis
authors: Massachusetts General Hospital Cancer Center, Harvard Medical School, Charlestown, Massachusetts 02129, USA;
authors: Nabeel
authors: N
authors: Bardeesy
authors: David H. Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA;
authors: Jacqueline A
authors: JA
authors: Lees
authors: Massachusetts General Hospital Cancer Center, Harvard Medical School, Charlestown, Massachusetts 02129, USA;
authors: Wilhelm
authors: W
authors: Haas
authors: Massachusetts General Hospital Cancer Center, Harvard Medical School, Charlestown, Massachusetts 02129, USA;
authors: Nicholas J
authors: NJ
authors: Dyson
mesh_terms: D000818:Animals; D002478:Cells, Cultured; D003106:Colon / Q000503:physiopathology; D005786:Gene Expression Regulation; D055786:Gene Knockout Techniques; D006801:Humans; D008168:Lung / Q000503:physiopathology; D051379:Mice; D008928:Mitochondria / Q000235:genetics / Q000378:metabolism*; D024101:Mitochondrial Proteins / Q000235:genetics / Q000378:metabolism; D010085:Oxidative Phosphorylation; D040901:Proteomics; D016160:Retinoblastoma Protein / Q000235:genetics* / Q000378:metabolism; D013312:Stress, Physiological / Q000235:genetics; D059467:Transcriptome
chemical_list: D024101:Mitochondrial Proteins; D016160:Retinoblastoma Protein
keywords: 13C-glucose; OXPHOS; metabolism; mitochondria; pRB; proteomics