A cross-over, randomised feasibility study of digitally printed versus hand-painted artificial eyes in adults: PERSONAL-EYE-S - a study protocol [version 2; peer review: 2 approved]

Background/objectives: Around 11,500 artificial eyes are required yearly for new and existing patients. Artificial eyes have been manufactured and hand-painted at the National Artificial Eye Service (NAES) since 1948, in conjunction with approximately 30 local artificial eye services throughout the country. With the current scale of demand, services are under significant pressure. Manufacturing delays as well as necessary repainting to obtain adequate colour matching, may severely impact a patient’s rehabilitation pathway to a normal home, social and work life. However, advances in technology mean alternatives are now possible. The aim of this study is to establish the feasibility of conducting a large-scale study of the effectiveness and cost-effectiveness of digitally printed artificial eyes compared to hand-painted eyes. Methods: A cross-over, randomised feasibility study evaluating a digitally-printed artificial eye with a hand-painted eye, in patients aged ≥18 years with a current artificial eye. Participants will be identified in clinic, via ophthalmology clinic databases and two charity websites. Qualitative interviews will be conducted in the later phases of the study and focus on opinions on trial procedures, the different artificial eyes, delivery times, and patient satisfaction. Discussion: Findings will inform the feasibility, and design, of a larger fully powered randomised controlled trial. The long-term aim is to create a more life-like artificial eye in order to improve patients’ initial rehabilitation pathway, long term quality of life, and service experience. This will allow the transition of research findings into benefit to patients locally in the short term and National Health Service wide in the medium to long term. ISRCTN registration: ISRCTN85921622 (prospectively registered on 17/06/2021

Role of ATP binding and hydrolysis in the gating of the cystic fibrosis transmembrane conductance regulator

The CFTR gene is unique within the ATP-binding cassette (ABC) protein family, predominantly of transporters, by coding a chloride channel. The gating mechanism of ABC proteins has been characterized by the ATP Switch model in terms cycles of dimer formation and dissociation linked to ATP binding and hydrolysis, respectively. It would be of interest to assess the extent that Cystic Fibrosis Transmembrane Conductance Regulator (CFTR), a functional channel, fits the ATP Switch model for ABC transporters. Additional transporter mechanisms, namely those of Pgp and HlyB, are discussed for perspective. Literature search of databases selected key references in comparing and contrasting the gating mechanism. CFTR is a functional chloride channel facilitating transmembrane anion flow down electrochemical gradients. A dysfunctional CFTR protein results in cystic fibrosis, a fatal pleiotropic disease currently managed symptomatically. Understanding the gating mechanism will help target drug development aimed at alleviating and curing the disease

Ruk is ubiquitinated but not degraded by the proteasome

The regulator of ubiquitous kinase (Ruk) protein, also known as CIN85 or SETA, is an adaptor-type protein belonging to the CD2AP/CMS family. It was found in complexes with many signaling proteins, including phosphoinositol (PtdIns) 3-kinase (EC 2.7.1.137), Cbl, GRB2, p130Cas and Crk. Functional analysis of these interactions, implicated Ruk in the regulation of apoptosis, receptor endocytosis and cytoskeletal rearrangements. We have recently demonstrated that overexpression of Ruk induces apoptotic death in neurons, which could be reversed by activated forms of PtdIns 3-kinase and PKB/Akt. Furthermore, Ruk was shown to be a negative regulator of PtdIns 3-kinase activity through binding to its P85 regulatory subunit [Gout, I., Middleton, G., Adu, J., Ninkina, N. N., Drobot, L. B., Filonenko, V., Matsuka, G., Davies, A.M., Waterfield, M. & Buchman, V. L. (2000) Embo J.19, 4015–4025]. Here, we report for the first time, that all three isoforms of Ruk (L, M and S) are ubiquitinated. Specific interaction between the E3 ubiquitin ligase Cbl and all three Ruk isoforms was demonstrated by coexpression studies in Hek293 cells. The interaction of Ruk M and S isoforms with Cbl was found to be mediated via heterodimerization with Ruk L. The use of proteosomal and lysosomal inhibitors clearly indicated that ubiquitination of Ruk L does not lead to its degradation. Based on this study, we propose a possible mechanism for the regulation of Ruk function by ubiquitination

Ruk is ubiquitinated but not degraded by the proteasome

The regulator of ubiquitous kinase (Ruk) protein, also known as CIN85 or SETA, is an adaptor-type protein belonging to the CD2AP/CMS family. It was found in complexes with many signaling proteins, including phosphoinositol (PtdIns) 3-kinase (EC 2.7.1.137), Cbl, GRB2, p130Cas and Crk. Functional analysis of these interactions, implicated Ruk in the regulation of apoptosis, receptor endocytosis and cytoskeletal rearrangements. We have recently demonstrated that overexpression of Ruk induces apoptotic death in neurons, which could be reversed by activated forms of PtdIns 3-kinase and PKB/Akt. Furthermore, Ruk was shown to be a negative regulator of PtdIns 3-kinase activity through binding to its P85 regulatory subunit [Gout, I., Middleton, G., Adu, J., Ninkina, N. N., Drobot, L. B., Filonenko, V., Matsuka, G., Davies, A.M., Waterfield, M. & Buchman, V. L. (2000) Embo J.19, 4015–4025]. Here, we report for the first time, that all three isoforms of Ruk (L, M and S) are ubiquitinated. Specific interaction between the E3 ubiquitin ligase Cbl and all three Ruk isoforms was demonstrated by coexpression studies in Hek293 cells. The interaction of Ruk M and S isoforms with Cbl was found to be mediated via heterodimerization with Ruk L. The use of proteosomal and lysosomal inhibitors clearly indicated that ubiquitination of Ruk L does not lead to its degradation. Based on this study, we propose a possible mechanism for the regulation of Ruk function by ubiquitination

Protein kinase C phosphorylates ribosomal protein S6 kinase beta II and regulates its subcellular localization

The ribosomal protein S6 kinase (S6K) belongs to the AGC family of Ser/Thr kinases and is known to be involved in the regulation of protein synthesis and the G1/S transition of the cell cycle. There are two forms of S6K, termed S6K{alpha} and S6Kß, which have cytoplasmic and nuclear splice variants. Nucleocytoplasmic shuttling has been recently proposed for S6K{alpha}, based on the use of the nuclear export inhibitor, leptomycin B. However, the molecular mechanisms regulating subcellular localization of S6Ks in response to mitogenic stimuli remain to be elucidated. Here we present data on the in vitro and in vivo phosphorylation of S6Kß, but not S6K{alpha}, by protein kinase C (PKC). The site of phosphorylation was identified as S486, which is located within the C-terminal nuclear localization signal. Mutational analysis and the use of phosphospecific antibodies provided evidence that PKC-mediated phosphorylation at S486 does not affect S6K activity but eliminates the function of its nuclear localization signal and causes retention of an activated form of the kinase in the cytoplasm. Taken together, this study uncovers a novel mechanism for the regulation of nucleocytoplasmic shuttling of S6KßII by PKC-mediated phosphorylation