Title: Investigating the multiple mechanisms of RNR regulation by small disordered proteins
Funder: Worldwide Cancer Research

Abstract: <p style="margin: 0cm 0cm 0pt; tab-stops: 49.65pt;"><span style="font-size: 11pt; font-family: &quot;Arial&quot;,&quot;sans-serif&quot;;">Ribonucleotide reductase (RNR) is highly regulated and produces dNDPs from NTPs. Well characterised regulatory mechanisms include allosteric activation, substrate inhibition, transcription, direct inhibition by intrinsically disordered proteins (IDPs) and subcellular subunit localisation. When RNR regulation is perturbed, dNTP levels increase or decrease and relative dNTP concentrations can vary. Such effects decrease genome stability. </span></p> <p style="margin: 0cm 0cm 0pt; tab-stops: 49.65pt;"><strong><span style="font-size: 11pt; font-family: &quot;Arial&quot;,&quot;sans-serif&quot;;">Cancer Relevance:</span></strong><span style="font-size: 11pt; font-family: &quot;Arial&quot;,&quot;sans-serif&quot;;"> In the treatment of myeloproliferative disorders, the RNR inhibitor hydroxyurea (known as hydroxycarbamide) is a treatment mainstay. In acute myeloid leukaemia, hydroxycarbamide can be initially effective in reducing the while cell count, but resistance is common and the disease cannot be controlled for long. However, due to oral bioavailability and good tolerability, hydroxycarbamide retains an important role as a low-intensive chemotherapeutic agent. Its use in other cancers is also being studied in various clinical trials including lymphoma, solid tumours; melanoma; pancreatic; prostate; breast; lung; rectal tumours. Surprisingly little is known about the antineoplastic mechanism of action or the mechanism of resistance.</span></p> <p style="margin: 0cm 0cm 0pt; tab-stops: 49.65pt;"><strong><span style="font-size: 11pt; font-family: &quot;Arial&quot;,&quot;sans-serif&quot;;">Specific aims:</span></strong><span style="font-size: 11pt; font-family: &quot;Arial&quot;,&quot;sans-serif&quot;;"> Two mechanism of RNR regulation have been characterised in yeast (direct inhibition and subcellular localisation) but not in humans. We recently identified an additional potential level of regulation. All three mechanisms are dependent on a small IDP. We propose to characterise the regulation of RNR by IDPs in a model eukaryote and to identify equivalent regulatory protein(s) in humans.</span></p> <p style="margin: 0cm 0cm 0pt; tab-stops: 49.65pt;"><strong><span style="font-size: 11pt; font-family: &quot;Arial&quot;,&quot;sans-serif&quot;;">Outline plan:</span></strong><span style="font-size: 11pt; font-family: &quot;Arial&quot;,&quot;sans-serif&quot;;"> We will apply classical/molecular genetics (structure function relationships, genome instability etc), structural biology (NMR of IDPs and derivative mutant proteins: how do they function?), sub-diffraction-limited microscopy (to understand the mechanistic details of how small IDPs regulate RNR) and affinity purification / mass spectrometry to identify equivalent human RNR regulators.</span></p> <p><strong><span style="font-size: 11pt; font-family: &quot;Arial&quot;,&quot;sans-serif&quot;; mso-fareast-font-family: SimSun; mso-bidi-language: AR-SA; mso-ansi-language: EN-GB; mso-fareast-language: ZH-CN;">Outcomes:</span></strong><span style="font-size: 11pt; font-family: &quot;Arial&quot;,&quot;sans-serif&quot;; mso-fareast-font-family: SimSun; mso-bidi-language: AR-SA; mso-ansi-language: EN-GB; mso-fareast-language: ZH-CN;"> Characterisation of the three distinct IDP-dependent RNR regulatory mechanism to contribute towards understanding mechanism of resistance to hydroxycarbamide and to unlock potential novel drug targets. Potential identification of human orthologs. </span></p>


Research activity codes: 1.1 NORMAL BIOLOGICAL DEVELOPMENT AND FUNCTIONING
Health categories: CANCER AND NEOPLASMS