Impact of neurotrophic factors combination therapy on retinitis pigmentosa

Objective We aimed to determine the location of neurotrophic receptors tropomyosin receptor kinase (Trk)B, TrkC, and ciliary neurotrophic factor receptor (CNTFR)α in the retina of retinal degeneration ( rd) mice and to explore the dynamic changes of B-cell lymphoma-2 (Bcl-2), Bcl-2-associated X-protein (Bax), and microtubule-associated protein light chain 3 (LC3) expression and ultrastructure in the retina of rd mice intravitreally injected with neurotrophic factors. Methods Rd mice aged 2 and 3 weeks post-natally (PN) received intravitreal injections of neurotrophic factors. Two weeks later, their retinas were harvested for the detection of Bax, Bcl-2, and LC3 mRNA and protein expression. Results TrkB and TrkC expression levels were lower at 3 weeks PN compared with 0, 1, and 2 weeks PN, but CNTFRα expression was still detected in certain layers. The three receptors were expressed in different retinal layers at the same timepoint. Bax expression was downregulated in, rhBDNF + rhCNTF, rhBDNF + rhNT-3, groups 2 weeks after intravitreal injection; Bcl-2 expression was upregulated in the rhBDNF + rhCNTF + rhNT-3 group at PN-4w; and LC3 expression was upregulated in rhBDNF + rhCNTF + rhNT-3 groups. Conclusions The combined use of neurotrophic factors had a more significant effect on Bax, Bcl-2, and LC3 expression than the same factors used alone.

Engineering a potent receptor superagonist or antagonist from a novel IL-6 family cytokine ligand

Interleukin-6 (IL-6) family cytokines signal through multimeric receptor complexes, providing unique opportunities to create novel ligand-based therapeutics. The cardiotrophin-like cytokine factor 1 (CLCF1) ligand has been shown to play a role in cancer, osteoporosis, and atherosclerosis. Once bound to ciliary neurotrophic factor receptor (CNTFR), CLCF1 mediates interactions to coreceptors glycoprotein 130 (gp130) and leukemia inhibitory factor receptor (LIFR). By increasing CNTFR-mediated binding to these coreceptors we generated a receptor superagonist which surpassed the potency of natural CNTFR ligands in neuronal signaling. Through additional mutations, we generated a receptor antagonist with increased binding to CNTFR but lack of binding to the coreceptors that inhibited tumor progression in murine xenograft models of nonsmall cell lung cancer. These studies further validate the CLCF1–CNTFR signaling axis as a therapeutic target and highlight an approach of engineering cytokine activity through a small number of mutations.

Cytokine-Like Factor 1, an Essential Facilitator of Cardiotrophin-Like Cytokine:Ciliary Neurotrophic Factor Receptor α Signaling and sorLA-Mediated Turnover

Cardiotrophin-like cytokine:cytokine-like factor-1 (CLC:CLF-1) is a heterodimeric neurotropic cytokine that plays a crucial role during neuronal development. Mice lacking CLC:CLF-1 die soon after birth due to a suckling defect and show reduced numbers of motor neurons. Humans carrying mutations in CLC:CLF-1 develop similar disorders, known as Sohar-Crisponi or cold-induced sweating syndrome, and have a high risk of early death. It is well known that CLC binds the ciliary neurotrophic factor receptor α (CNTFRα) and is a prerequisite for signaling through the gp130/leukemia inhibitory factor receptor β (LIFRβ) heterodimer, whereas CLF-1 serves to promote the cellular release of CLC. However, the precise role of CLF-1 is unclear. Here, we report that CLF-1, based on its binding site for CLC and on two additional and independent sites for CNTFRα and sorLA, is a key player in CLC and CNTFRα signaling and turnover. The site for CNTFRα enables CLF-1 to promote CLC:CNTFRα complex formation and signaling. The second site establishes a link between the endocytic receptor sorLA and the tripartite CLC:CLF-1:CNTFRα complex and allows sorLA to downregulate the CNTFRα pool in stimulated cells. Finally, sorLA may bind and concentrate the tripartite soluble CLC:CLF-1:CNTFRα complex on cell membranes and thus facilitate its signaling through gp130/LIFRβ.