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It is well-known that DNA binding of native nine zinc-finger protein TEIIIA is dominated by interaction of select few fingers. Newly designed zinc-finger peptide Sp1ZF9 containing nine Cys2-His2 type motifs has been manipulated. The DNA-binding property of Sp1ZF9 was compared with those of native three zinc-finger Sp1(530-623) and artificial six zinc-finger Sp1ZF6 peptides. Although the equilibrium time was less than 0.5 h for Sp1(530-623)-DNA complex, Sp1ZF6 and Sp1ZF9 required approximately 48 and 72 h, respectively, for full complex formation. Evidently, the footprinting analysis demonstrated that Sp1ZF9 and Sp1ZF6 bind at least 27 and 18 contiguous base pairs of DNA sequence, respectively. Sp1ZF9 showed two step bindings to DNA, namely first the recognition of GC (5'-GGG-GCG-GGGCC-3') sequence by the N-terminal Sp1 domain and next the recognition of the corresponding target sequences by the middle and C-terminal Sp1 domains. In contrast with unimolecular binding of Sp1ZF9 and Sp1ZF6, two Sp1(530-623) molecules bind to one GCIII (5'-GGG-GCG-GGG-GGG-GCG-GGG-GGG++ +-GCG-GGGCC-3') site region. Semispecific complex formed at the beginning of Sp1ZF9-DNA interaction has also been characterized by kinetic analysis using surface plasmon resonance. Interestingly, the association rate constants for GC and GCIII complexes of Sp1ZF9 are smaller than those of the corresponding Sp1(530-623) complexes. Of special interest is the fact that new nine zinc-finger peptide Sp1ZF9 can bind to DNA sequence of approximately 30 base pairs. Such multi zinc-finger peptides may be useful as genome-specific transcriptional switches in future.

Arginine-rich peptide-mediated protein delivery into living cells is a novel technology for controlling cell functions with therapeutic potential. In this report, a novel approach for the intracellular delivery of histidine-tagged proteins was introduced where a Ni(II) chelate of octaarginine peptide bearing nitrilotriacetic acid [R8-NTA-Ni(II)] was used as a membrane-permeable carrier molecule. Significant internalization of histidine-tagged enhanced green fluorescent protein (EGFP) into HeLa cells was observed by confocal microscopic observation in the presence of R8-NTA-Ni(II). Nuclear condensation characteristic in apoptotic cell death was also induced in the cells treated with a histidine-tagged apoptosis-inducing peptide [pro-apoptotic domain peptide (PAD)], indicating that the cargo molecules really went through the membrane to reach the cytosol. The apoptosis-inducing activity of the peptide thus delivered was compared with that of the PAD peptide covalently connected with the octaarginine peptide.

Tofacitinib is an oral Janus kinase inhibitor that is being investigated for psoriasis and psoriatic arthritis. Japanese patients aged 20 years or more with moderate to severe plaque psoriasis and/or psoriatic arthritis were double‐blindly randomized 1:1 to tofacitinib 5 or 10 mg b.i.d. for 16 weeks, open‐label 10 mg b.i.d. for 4 weeks, then variable 5 or 10 mg b.i.d. to Week 52. Primary end‐points at Week 16 were the proportion of patients achieving at least a 75% reduction in Psoriasis Area and Severity Index (PASI75) and Physician's Global Assessment of “clear” or “almost clear” (PGA response) for psoriasis, and 20% or more improvement in American College of Rheumatology criteria (ACR20) for patients with psoriatic arthritis. Safety was assessed throughout. Eighty‐seven patients met eligibility criteria for moderate to severe plaque psoriasis (5 mg b.i.d., n = 43; 10 mg b.i.d., n = 44), 12 met eligibility criteria for psoriatic arthritis (5 mg b.i.d., n = 4; 10 mg b.i.d., n = 8) including five who met both criteria (10 mg b.i.d.). At Week 16, 62.8% and 72.7% of patients achieved PASI75 with tofacitinib 5 and 10 mg b.i.d., respectively; 67.4% and 68.2% achieved PGA responses; all patients with psoriatic arthritis achieved ACR20. Responses were maintained through Week 52. Adverse events occurred in 83% of patients through Week 52, including four (4.3%) serious adverse events and three (3.2%) serious infections (all herpes zoster). No malignancies, cardiovascular events or deaths occurred. Tofacitinib (both doses) demonstrated efficacy in patients with moderate to severe plaque psoriasis and/or psoriatic arthritis through 52 weeks; safety findings were generally consistent with prior studies.

Zinc finger constitutes one of the most common DNA binding motifs. Although zinc finger proteins consisting of Cys2His2, Cys3His, Cys4, and Cys6 domains are known in nature, a novel His4 zinc finger protein has never been observed. Herein, we have created the first artificial His4-type zinc finger protein (H4Sp1) engineered by Cys → His mutations of the Cys2His2-type zinc finger transcription factor Sp1. The CD features of the single finger H4Sp1f2 and three-finger H4Sp1 clearly demonstrate the folding of the mutant His4 peptides by complexation with Zn(II). The NMR study of Zn(II)-H4Sp1f2 reveals that some distortions of the helical region occur due to Zn(II) coordination. The gel mobility shift assay and DNase I footprinting analysis strongly show the binding of Zn(II)-H4Sp1 to the GC-box site of duplex DNA. The methylation interference pattern of Zn(II)-H4Sp1 binding significantly resembles that of the corresponding C2H2Sp1 binding. The present artificial peptide H4Sp1 is the first example of a zinc finger containing the His4 domain. Of special interest is the fact that the zinc finger domains of H4Sp1 are folded (although not identical to the native structure) and bind DNA similar to wild-type C2H2Sp1.

No abstract

By using some mutant peptides of transcription factor Spl, phosphate backbone contacts with the DNA binding protein containing three zinc fingers have been investigated by alkylation interference, circular permutation, DNase I footprinting, and methylation protection methods. The ethylation interference analyses of Spl(R565S) and Spl(K595S) mutants demonstrate that arginine at 565 position and lysine at 595 position interact with the phosphate between G(3) and G(4) and with the phosphate between G(9) and G(10) in GC-box DNA, respectively. On the basis of the experimental results for Spl(K535G), Sp1(537-623), and Sp1(530-623), lysine and glutamine at 535 and 536 positions have been clarified to be in contacts with phosphate between G(7) and G(8) and with phosphate outside GC-box, respectively. In particular, glutamine at the N-terminal side of zinc finger 1 is a key amino acid residue to induce DNA bending and also participates in total base specificity of Sp1. The present study strongly indicates that (1) each zinc finger is not independent for the DNA interaction with Sp1 and (2) DNA base recognition of the zinc finger protein is influenced by local conformational change of DNA induced by the protein binding.

Off-target interactions between reactive hydrogel moieties and drug cargo as well as slow reaction kinetics and the absence of controlled protein release over an extended period of time are major drawbacks of chemically cross-linked hydrogels for biomedical applications. In this study, the inverse electron demand Diels−Alder (iEDDA) reaction between norbornene-and tetrazine-functionalized eight-armed poly(ethylene glycol) (PEG) macromonomers was used to overcome these obstacles. Oscillatory shear experiments revealed that the gel point of a 15% (w/v) eight-armed PEG hydrogel with a molecular weight of 10 kDa was less than 15 s, suggesting the potential for fast in situ gelation. However, the high-speed reaction kinetics result in a risk of premature gel formation that complicates the injection process. Therefore, we investigated the effect of polymer concentration, temperature, and chemical structure on the gelation time. The cross-linking reaction was further characterized regarding bioorthogonality. Only 11% of the model protein lysozyme was found to be PEGylated by the iEDDA reaction, whereas 51% interacted with the classical Diels−Alder reaction. After determination of the mesh size, fluorescein isothiocyanate−dextran was used to examine the release behavior of the hydrogels. When glucose oxidase was embedded into 15% (w/v) hydrogels, a controlled release over more than 250 days was achieved. Overall, the PEG-based hydrogels cross-linked via the fast iEDDA reaction represent a promising material for the long-term administration of biologics.