Fragment Of Histone H1 Research Articles

Altered Expression of Nuclear and Cytoplasmic Histone H1 in Pulmonary Artery and Pulmonary Artery Smooth Muscle Cells in Patients with IPAH

The pathogenesis of idiopathic pulmonary hypertension is poorly understood. This paper utilized histology-based Matrix-Assisted Laser Desorption Ionization Mass Spectrometry (MALDI MS) to identify as-yet unknown proteins that may be associated with the structural changes in the pulmonary arterial walls of patients with IPAH. The technology identified significant increases in two fragments of histone H1 in the IPAH cases compared to controls. This finding was further examined using immunofluorescence techniques applied to sections from IPAH and control pulmonary arteries. In addition, cultured pulmonary artery smooth muscle cells (PASMCs) were utilized for Western analysis of histone H1 and importin β and importin 7, immunoprecipitation and assessment of nucleosomal repeat length (NRL). Immunofluorescence techniques revealed that nuclear expression of histone H1 was decreased and the chromatin was less compact in the IPAH cases than in the controls; furthermore, some cases showed a marked increase in cytoplasmic histone H1 expression. Using nuclear and cytoplasmic fractions of cultured PASMCs, we confirmed the reduction in histone H1 in the nucleus and an increase in the cytoplasm in IPAH cells compared to controls. Immunoprecipitation demonstrated a decreased association of histone H1 with importin β while importin 7 was unchanged in the IPAH cells compared to controls. The assessment of NRL revealed that the distance between nucleosomes was increased by ~20 bp in IPAH compared to controls. We conclude that at least two factors contribute to the reduction in nuclear histone H1—fragmentation of the protein and decreased import of histone H1 into the nucleus by importins. We further suggest that the decreased nuclear H1 contributes the less compact nucleosomal pattern in IPAH and this, in turn, contributes to the increase in NRL.

Antimicrobial activity of histones from hemocytes of the Pacific white shrimp

The role of vertebrate histone proteins or histone derived peptides as innate immune effectors has only recently been appreciated. In this study, high levels of core histone proteins H2A, H2B, H3 and H4 were found in hemocytes from the Pacific white shrimp, Litopenaeus vannamei. The proteins were identified by in-gel digestion, mass spectrometry analysis, and homology searching. The L. vannamei histone proteins were found to be highly homologous to histones of other species. Based on this homology, histone H2A was cloned and its N-terminus was found to resemble the known antimicrobial histone peptides buforin I, parasin, and hipposin. Consequently, a 38 amino acid synthetic peptide identical to the N-terminus of shrimp H2A was synthesized and assayed, along with endogenous histones H2A, H2B, and H4, for growth inhibition against Micrococcus luteus. Histone H2A, purified to homogeneity, completely inhibited growth of the Gram-positive bacterium at 4.5 microm while a mixture of histones H2B and H4 was active at 3 microm. In addition, a fraction containing a fragment of histone H1 was also found to be active. The synthetic peptide similar to buforin was active at submicromolar concentrations. These data indicate, for the first time, that shrimp hemocyte histone proteins possess antimicrobial activity and represent a defense mechanism previously unreported in an invertebrate. Histones may be a component of innate immunity more widely conserved, and of earlier origin, than previously thought.

Specificity of Auto Antibodies to Histone H1 in SLE: Relationship to DNA-Binding Domains

Autoantibodies in the sera of patients with systemic lupus erythematosus were examined with respect to their specificity for proteolytic fragments of histone H1 that retain, or do not retain, DNA-binding domains. 16 of 31 sera contained IgG and IgM antibodies to histone H1. IgM antibodies to H1 in 8 sera (50%) were directed at 18 kD and 20 kD alpha-chymotrypic H1 fragments that bore binding sites for DNA, as identified by staining immunoblots containing the fragments with ssDNA plus 6/0, a mouse monoclonal antibody against ssDNA, IgM with this type of histone H1 specificity did not react with comparably-sized V8 protease fragments of H1. IgM antibodies to H1 in the other patients were directed against entirely different epitopes which were preserved in V8 protease digests of H1. In serial studies of three patients during different phase of their SLE, the level of antibodies against the 18 kD and 20 kD histone H1 fragments varied in parallel with the level of anti-ssDNA antibodies in one and varied inversely in the other two. The data suggest that a significant proportion of autoantibodies to histone H1 are directed at a limited number of epitopes localized to H1 fragments containing DNA-binding sites.

Comparative investigation of the structure of complexes of DNA with the polypeptide fragment 152–184 of histone H1 and the polypeptide (Lys-Ala-Ala)n

The interactions with DNA of a synthetic peptide fragment of histone H1 33 amino acid residues long the sequence of which corresponds to fragment 152–184 and of a synthetic polypeptide (Lys-Ala-Ala)n modeling the properties of the C-terminal fragments of histone H1 have been studied by the CD method. The use of the CD method for recording the spectra of the polypeptides under investigation in the free state and of the artificial complexes of DNA formed with them has permitted the characterization of different structural possibilities of the polypeptides in solution and of their complexes with DNA, and the conformational changes of the components of the complex under various ionic conditions.

Histones H1(0) and H5 share common epitopes with RNA polymerase II.

We report here the cross-reaction of RNA polymerase II antiserum with histones H1(0) and H5 and the complementary cross-reactions of antisera to the globular domain of histone H1(0) (GH1(0)) and histone H5 (GH5) with RNA polymerase II. Immunoblotting of RNA polymerase II antiserum with fragments of histone H1(0) localized the cross-reaction at the junction of the globular and C-terminal domains of histone H1(0). The structural homology implied by these cross-reactions is interesting in light of reports that suggest H1(0) may play a role in differentiation and development.