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PubMed1993

Neuronal death, cytoplasmic calcium and internucleosomal DNA fragmentation: evidence for DNA fragments being released from cells.

Neuronal death, secondary to endogenous agents such as glutamate, may involve changes in cytoplasmic calcium. Besides its well recognized role as a second messenger mediating cellular response, calcium is necessary for the activation of endonuclease(s), resulting in DNA fragmentation and cell death. Therefore, we investigated the relationship between changes in cytoplasmic calcium, DNA fragmentation and neuronal death, using PC12 and NCB-20 cell lines. The calcium ionophore, A23187, caused a dose-dependent increase in cytoplasmic calcium, loss of cell viability, increased lactate dehydrogenase (LDH)-release, and DNA fragmentation. DNA fragments, typical of internucleosomal digestion of genomic DNA, characteristic of endonuclease(s) activation, were consistently detected in the incubating medium. Release of DNA fragments into the medium was seen with A23187 in concentrations as low as 10 nM, and within an hour of treatment. Furthermore, calcium added to preparations of PC12 nuclei also produced DNA fragmentation, although, less pronounced than when intact cells were treated with A23187. The findings indicate that A23187-induced neuronal death involves the activation of endonuclease(s). The role of cytoplasmic calcium in this process is supported by evidence that A23187 selectively mobilizes cytoplasmic calcium, and that calcium can directly activate endonuclease(s) in nuclear preparations.

Animals↗
PubMed1993

Transient acoustic cavitation in gallstone fragmentation: a study of gallstones fragmented in vivo.

The mechanism of gallstone fragmentation by shock waves in vivo is uncertain. We used scanning electron microscopy to study 9 partially fragmented stones obtained from 6 patients who underwent lithotripsy and subsequently had surgery because of incomplete fragmentation. Surface characteristics of the stone were studied using scanning electron microscopy and compared to gallstones fragmented in degassed water in vitro and to control stones obtained from patients with uncomplicated cholelithiasis. Characteristic damage caused by transient acoustic cavitation was visible in all stones fragmented in vivo and in vitro as pits 10-100 microns diameter. In these pits, cholesterol crystals were fractured, and the symmetry of crystal boundaries was damaged. In areas of more severe damage, individual pits coalesced to form craters on the stone surface. High magnification of the pit walls revealed cracks, which in some instances radiated out onto the unpitted surface of the stone. We conclude that transient acoustic cavitation plays a role in gallstone fragmentation in vivo through the mechanism of surface pitting and the formation of cracks that radiate outward from the surface pits. Measures to enhance cavitation may improve the results of gallstone lithotripsy.

Adult↗
PubMed1977

Transformation with specific fragments of adenovirus DNAs. II. Analysis of the viral DNA sequences present in cells transformed with a 7% fragment of adenovirus 5 DNA.

Five clones of rat kidney cells transformed by a small restriction endonuclease fragment of adenovirus 5 (Ad5) DNA (fragment HsuI G, which represents the left terminal 7% of the adenovirus genome) were analyzed with respect to the viral DNA sequences present in the cellular DNAs. In these analyses, the kinetics of renaturation of 32P-labeled specific fragments of Ad5 DNA was measured in the presence of a large amount of DNA extracted either from each of the transformed cell lines or from untransformed cells. The fragments were produced by digestion of 32P-labeled adenovirus 5 DNA with endo R.HsuI, or by digestion of 32P-labeled fragment HsuI G of adeno 5 DNA with endo R.HpaI. All five transformed lines were found to contain DNA sequences homologous to 75--80% of Ad5 fragment HsuI G only. Clones II and V contained approximately 48 copies per quantity of diploid cell DNA, clone VI about 35 copies, clone IV 22 copies and clone III 5--10 copies. These results indicate that a viral DNA segment as small as 5.5% of the Ad5 genome, contains sufficient information for the maintenance of transformation.

Adenoviruses, Human↗
PubMed1975

Amino-acid incorporation into tRNA fragments and into heterologous combinations of fragments.

When the CCA-halves of tRNAAla1(yeast) and tRNAVal1(Escherichia coli) were incubated with the pG-halves of tRNAVal1 (E.coli) and trnaala1 (yeast), respectively, heterologous complexes were detected. When a 10-fold excess of one half was applied, up to 50% of the other half could be complexed. 5--12% alanine and valine incorporation was observed into the heterolgous combinations in which the pG-halves were derived from tRNAAla1 (yeast) and tRNAVal1 (E.coli), respectively. Although the values are small they appear to be significant considering the results of a number of control experiments. The CCA-half of tRNASer1,2(yeast) and another fragment of this tRNA which extends from the dihydrouridine region to the CCA-terminus were inactive in the aminoacylation assay but they could be converted into a form which accepted serine under standard conditions even in the absence of a complementary fragment. One activation procedure involved the addition of MgCl2 to Mg2+-free fragment solutions, the other consisted in a brief heating-cooling cycle of the fragment solutions at low Mg2+ concentrations. With the two procedures up to 20% or up to 40%, respectively, of the maximal serine incorporation were achieved. At 37 degrees C the active conformation of the fragments persisted only for a few minutes. Analogously, the CCA-halves of tRNAPhe (yeast), tRNAAla1 (yeast), and tRNAVal1 (E.coli)could be activated although here the extent of aminoacylation varied greatly from one experiment to the other. Mischarging of the activated CCA-halves of tRNASer1,2 (yeast) and tRNAPhe (yeast) with phenylalanine and serine, respectively, was not observed. The results obtained with the hererologous fragment combinations and with the CCA-halves alone, which at first sight seem to contradict each other, are discussed with respect to the conformational requirements of synthetase-tRNA recognition.

Alanine↗
PubMed1994

Excision of DNA fragments corresponding to the unit-length a sequence of herpes simplex virus type 1 and terminus variation predominate on one side of the excised fragment.

DNA fragments corresponding to the unit-length a sequence of herpes simplex virus type 1 (HSV-1) were identified in HSV-1 DNA preparations extracted by the method of Hirt. The DNA fragments were molecularly cloned, and nucleotide sequences were determined. Most termini of the fragments were at sites on DR1 corresponding to the termini of linear HSV-1 DNA generated by the cleavage-packaging system. In one-step growth experiments, DNA fragments of the unit-length a sequence appeared simultaneously with the termini of linear HSV-1 DNAs produced by cleavage of circular and concatemeric DNAs. Therefore, excision of the unit-length a sequence appeared closely related to the cleavage-packaging system. Termini of the excised DNA fragments of the variant a sequence with two DR2 arrays varied on the L-component side, while termini on the S-component side were at the site on DR1 corresponding to the authentic cleavage site. It is thus assumed that the cleavage-packaging system functions adequately on the DR1 second distal from the S component, and cleavages of other DR1 are rare and less accurate. If this notion is tenable, then most termini on the S-component side of the excised DNA fragments are derived from the second DR1 properly cleaved and should be constant, while termini on the L-component side are from regions on and around the DR1 third distal from the S component and may be variable. Cleavage of DR1 is likely to be affected by the topological relationship with the S component.

Animals↗
PubMed1982

Antigenic polypeptide fragments of a receptor related to the Fab fragment of human immunoglobulin from thymus-derived lymphocytes.

Certain thymus-derived lymphocytes of man and other primates express surface components related to the variable region of immunoglobulin heavy chains but lack constant region determinants defining any known immunoglobulin class. To obtain structural information on this molecule that can be used for comparison with known immunoglobulins and other surface molecules, we isolated the T cell-derived molecule by affinity chromatography using an antiserum raised against the monomeric Fab fragment of a human Waldenström macroglobulin and subjected the isolated molecule to either proteolysis using enzymes or cleavage with cyanogen bromide, followed by isolation of polypeptides which bore the Fab- or heavy chain variable region (VH)-related antigenic markers. The intact T cell molecule had an apparent mass of 68,000 daltons and no evidence was found for covalent or noncovalent association with polypeptides resembling light chains in apparent mass. The pattern of fragments obtained by cleavage of the T cell heavy chain suggests that the molecule is comprised of domains of approximate mass 12,000 daltons. Isolation of fragments from the digests that bear Fab-related serological markers shows that the molecule can be degraded into fragments resembling the Fd and VH of standard immunoglobulin heavy chains. A procedure was developed enabling the isolation of milligram quantities of VH-related T cell products. These results support the concept of a sharing of combining site determinants between T cell receptors and immunoglobulin heavy chains and show a general formal similarity between the two classes of molecules, even though they lack shared constant region determinants. The susceptibility of the T cell molecule to be cleaved into discrete antigenic fragments by controlled proteolysis might help to explain the plethora of sizes observed for antigen-specific T cell factors.

Animals↗
PubMed1996

Granzyme B/perforin-mediated apoptosis of Jurkat cells results in cleavage of poly(ADP-ribose) polymerase to the 89-kDa apoptotic fragment and less abundant 64-kDa fragment.

Cytotoxic lymphocytes utilize granule associated serine proteases (granzymes) and perforin to induce apoptosis. Although the importance of granzyme B has been established by gene ablation experiments, biochemical events initiated by the granzyme remain enigmatic. We show here that exposure of Jurkat cells to granzyme B and perforin results in cleavage of poly(ADP-ribose) polymerase to an apoptotic 89 kDa fragment and to lesser amounts of a 64 kDa fragment. The 64 kDa fragment is produced directly by granzyme B while the 89 kDa fragment is presumably generated by activated ICE/Ced-3 proteases. Establishing the intracellular function of GrB in the apoptotic response, these results indicate that granzyme B enters perforin treated targets activating the ICE/Ced-3 family proteases which then cleave poly(ADP-ribose) polymerase to its apoptotic fragment. Intracellular granzyme B appears to be translocated to the nucleus where the protease directly cleaves poly(ADP-ribose) polymerase.

Apoptosis↗
PubMed1988

Human B-cell differentiation by Fc fragment of IgG. I. Fc fragment from human IgG induces plasma cell generation but cannot induce lymphocyte proliferation.

Circulating mononuclear cells (MNC) from normal donors were examined for lymphocyte proliferation and plasma cell differentiation following stimulation by Fc and Fab fragments or by intact IgG. Lymphocyte differentiation and DNA synthesis were examined as a function of culture duration and concentration of Fc, Fab fragments, and IgG. Plasma cells containing intracytoplasmic Ig were demonstrated by immunofluorescence with a polyvalent antiserum to human immunoglobulin and with specific antisera (anti-mu, -gamma, -alpha, -delta, -kappa, and -lambda chains). DNA synthesis of mononuclear cells cultures was analyzed by measuring [3H]thymidine incorporation. The results indicated that only the Fc fragments are able to induce the differentiation of B cells. The polyclonal plasma cell response to Fc fragments was dose dependent, peaked on the sixth day of culture, and was isotypically diverse (IgM greater than IgA greater than IgG). This activity requires the presence of T helper cells and monocytes. In contrast, the Fc fragments were unable to induce a proliferative response.

Adult↗
PubMed1991

Isolation of alpha 6 beta 1 integrins from platelets and adherent cells by affinity chromatography on mouse laminin fragment E8 and human laminin pepsin fragment.

Ligand affinity chromatography was used to identify receptors on platelets and two adherent cell lines, OV-CAR-4 and HBL-100, for the E8 fragment of murine laminin. A complex of two polypeptides (140 and 110 kDa nonreduced) was bound by the E8 affinity columns from all three cell types and was eluted with EDTA. This heterodimeric complex was identified as the alpha 6 beta 1 integrin by immunoprecipitation with specific antibodies against either the alpha 6 or the beta 1 subunit. The alpha 6 beta 1 integrin did not bind to an affinity column containing fragment P1 originating from a different part of murine laminin which, however, bound the alpha IIb beta 3 integrin from platelets. Furthermore, in immunofluorescence staining, the alpha 6 beta 1 integrin localizes in focal contacts of OVCAR-4 cells attached to laminin and E8 but not to fibronectin substrates. These results, combined with previous antibody inhibition studies, unequivocally identify the alpha 6 beta 1 integrin as a specific receptor for fragment E8. Affinity chromatography of OVCAR-4 and HBL-100 cells on a large pepsin fragment of laminin from human placenta yielded integrin alpha 3 beta 1. When alpha 3 beta 1 was removed from lysates of OVCAR-4 cells by preclearing with an alpha 3-specific monoclonal antibody, alpha 6 beta 1 was able to bind to human laminin as well. Integrin alpha 6 beta 1 on platelets which do not express alpha 3 beta 1 binds directly to human laminin. These results indicate that both alpha 3 beta 1 and alpha 6 beta 1 can act as receptors for human laminin and may interfere by steric hindrance. The alpha 6 beta 4 complex, which is strongly expressed on HBL-100 cells, did not bind to either mouse laminin fragment E8 or human laminin affinity columns.

Amino Acid Sequence↗
PubMed1995

Interaction of the 47-kDa talin fragment and the 32-kDa vinculin fragment with acidic phospholipids: a computer analysis.

In recent in vitro experiments, it has been demonstrated that the 47-kDa fragment of the talin molecule and the 32-kDa fragment of the vinculin molecule interact with acidic phospholipids. By using a computer analysis method, we determined the hydrophobic and amphipathic stretches of these fragments and, by applying a purpose-written matrix method, we ascertained the molecular amphipathic structure of alpha-helices. Calculations for the 47-kDa mouse talin fragment (residues 1-433; NH2-terminal region) suggest specific interactions of residues 21-39, 287-342, and 385-406 with acidic phospholipids and a general lipid-binding domain for mouse talin (primary amino acid sequence 385-401) and for Dictyostelium talin (primary amino acid sequence 348-364). Calculations for the 32-kDa chicken embryo vinculin fragment (residues 858-1066; COOH-terminal region) and from nematode vinculin alignment indicate for chicken embryo vinculin residues 935-978 and 1020-1040 interactions with acidic phospholipids. Experimental confirmation has been given for vinculin (residues 916-970), and future detailed experimental analyses are now needed to support the remaining computational data.

Amino Acid Sequence↗
PubMedDate not supplied

Monoclonal antibody Fab' fragment cross-linking using equilibrium transfer alkylation reagents. A strategy for site-specific conjugation of diagnostic and therapeutic agents with F(ab')2 fragments.

An investigation was conducted to evaluate the feasibility of site-selective addition of diagnostic and therapeutic agents to monoclonal antibody F(ab')2 fragments through cross-linking of antibody Fab' fragments. In the investigation, trifunctional equilibrium transfer alkylation cross-link (ETAC) reagents, 4-[2,2-bis[(p-tolylsulfonyl)methyl]acetyl]benzoic acid, 1a, N-[4-[2,2bis[(p-tolylsulfonyl)methyl]acetyl]-benzoyl]-4- (tri-n-butylstannyl)phenethylamine, 3a, and N-[4-[2,2-bis[(p-tolylsulfonyl)methyl]acetyl]- benzoyl]-4-[125,131I]iodophenethylamine, 3b, were synthesized. The ETAC derivatives were reacted with Fab' fragments of an antirenal cell carcinoma antibody (A6H) produced from reduction of F(ab')2 using 1,4-dithiothreitol. Cross-linking of Fab' was obtained to yield a radioiodinated modified F(ab')2, [mF(ab')2], fragment. The cross-linking reaction produced mixed addition products, requiring the desired mF(ab')2 to be separated from radioiodinated Fab' by size exclusion HPLC. Tumor cell binding immunoreactivities varied (60-90%) for five isolated mF(ab')2 preparations but were consistent with other radiolabeled antibody preparations tested on the same day. In vitro stability testing indicated that the mF(ab')2 was reasonably stable toward loss of the ETAC cross-linking reagent, except under strongly basic conditions. Under reducing sodium dodecylsulfate-polyacrylamide gel electrophoresis (SDS-PAGE) analyses, protein bands believed to be cross-linked heavy chain dimers were observed. Biodistribution of purified radioiodinated A6H mF(ab')2 was conducted in athymic mice bearing a renal cell carcinoma xenograft (TK-82). A nonmodified control A6H F(ab')2, radioiodinated as a p-[125,131I]-iodobenzoyl conjugate, was coinjected for comparison. The radioiodionated mF(ab')2 had a similar distribution to the radioiodinated control at 3.5, 19, and 43 h postinjection. In another study, the distribution of radioiodinated A6H Fab' was evaluated at 4 and 24 h to establish clearance and pharmacokinetics for comparison with the data obtained from the mF(ab')2. The biodistribution data indicated that A6H mF(ab')2 was quite different from that of A6H Fab'. The results from this preliminary study suggest that it may be possible to attach (large polymeric) diagnostic or therapeutic agents to monoclonal antibody F(ab')2 fragments through the use of ETAC reagents.

Alkylating Agents↗
PubMed1994

Structural and dynamic properties of the Fv fragment and the single-chain Fv fragment of an antibody in solution investigated by heteronuclear three-dimensional NMR spectroscopy.

Fv fragments, heterodimers of the variable light (VL) and variable heavy chain (VH) domains, are the smallest functional antibody units with molecular masses of approximately 26 kDa. The structural and dynamic properties of the Fv fragment and the corresponding single-chain Fv fragment (scFv: VH-linker-VL, 252 amino acids) of the phosphorylcholine-binding antibody McPC603 in the presence of hapten have been studied in solution by heteronuclear multidimensional NMR spectroscopy. Both 15N TOCSY-HMQC and triple-resonance experiments (HNCA and HN(CA)H, with 15N-13C-labeled protein) gave poor spectra, due to short T2 relaxation times for most of the backbone 1H, 15N, and 13C alpha atoms. The assignment procedure therefore relied upon the combination of amino acid and domain (VL) specifically labeled spectra and the 3D NOESY-HMQC spectrum of the uniformly 15N labeled Fv and scFv fragments. Approximately 80% of the 15N and 1H backbone and 60% of the 1H side-chain resonances have been assigned. Short- and long-range NOEs were used to determine the extent of beta-sheet structure and were compared to the X-ray crystallographic data. The 1H-15N NOE data indicate that the scFv backbone has a well-defined structure of limited conformational flexibility. However, the linker of the scFv fragment exhibits substantial fast internal motion (on the picosecond to nanosecond time scale) compared with the overall rotational correlation time of the whole molecule. Several residues in the CDRs, in turns, or at the C-terminal end of the protein have smaller NOEs, reflecting some degree of rapid motion in the protein backbone.

Amino Acid Sequence↗
PubMed1994

Generation of a family of protein fragments for structure-folding studies. 2. Kinetics of association of the two chymotrypsin inhibitor-2 fragments.

The kinetics of association of the fragments of the barely chymotrypsin inhibitor-2, CI-2(20-59) and CI-2(60-83), to form a native-like structure follows two phases. There is a major second-order component with rate constant (3.7 +/- 0.3) x 10(3) M-1 s-1 and a slow first-order phase of rate constant 0.011 +/- 0.001 s-1. The major phase contains a cooperative folding process as judged by the secondary structure recovery in parallel with the fluorescence change. The time course for structure formation has uniform changes at all of the wavelengths of the circular dichroism spectra, suggesting that all elements of secondary structure are formed simultaneously. A series of kinetic experiments suggest that the association and folding occur in the second-order step and that the first-order step probably results from a cis-trans peptidylprolyl isomerization in the fragment CI-2(20-59). This was confirmed by experiments on fragments derived from two mutants whose parent proteins fold more slowly than wild-type CI-2. Those fragments display lower second-order rate constants, but the rate constants of the first-order phase are the same as for wild type. The experiments suggest that the mechanism of the association/folding of mutant fragments may be studied by a protein-engineering analysis.

Circular Dichroism↗
PubMed1981

Two contiguous thrombin fragments of human somatotropin form a functionally active recombinant, but the two homologous fragments from sheep hormone do not.

Two thrombin fragments of reduced-carbamidomethylated human somatotropin representing the full primary structure of the native hormone (residues 1-134 and 135-191) have been found to form a recombinant molecule with properties similar to those of reduced-carbamidomethylated human somatotropin as shown by circular dichroism spectroscopy, two receptor-binding assays, and radioimmunoassay. In contrast, the homologous thrombin fragments of reduced-carbamidomethylated sheep hormone (residues 1-133 and 134-191) do not undergo recombination. Furthermore, neither the reduced-alkylated nor the reduced and nonalkylated C-terminal thrombin fragment of sheep hormone is able to interact with the reduced-carbamidomethylated N-terminal thrombin fragment of human hormone, under conditions which favor the recombination of the two human somatotropin fragments.

Amino Acid Sequence↗
PubMed1975

Fragments of bovine serum albumin produced by limited proteolysis. Isolation and characterization of peptic fragments.

Five new fragments of bovine serum albumin have been isolated following limited peptic hydrolysis. These fragments, and the two peptic fragments previously described by King (King, T.P. (1973), Arch. Biochem. Biophys. 156, 509), were positioned within the albumin sequence published by Brown (Brown, J.R. (1975), Fed. Proc., Fed. Am. Soc. Exp. Biol. 34, 591) on the basis of molecular weight, amino acid composition, and amino- and carboxyl-terminal sequences. The fragments correspond to residues 1-385, 1-306, 307-581, 49-185, 186-306, 307-385, and 353-503 in the albumin sequence. These peptides are likely to be native in structure since disulfide bonds were not cleaved during their preparation. In each case the amino acid composition and terminal sequences have confirmed the bovine serum albumin sequence and disulfide bridging pattern proposed by Brown, and the offer further proof that bovine albumin is composed of a series of nine independent loops. These fragments should be useful in elucidating the structure-function relationships of albumin.

Amino Acid Sequence↗
PubMed1999

Characterization of stromelysin 1 (MMP-3), matrilysin (MMP-7), and membrane type 1 matrix metalloproteinase (MT1-MMP) derived fibrin(ogen) fragments D-dimer and D-like monomer: NH2-terminal sequences of late-stage digest fragments.

Matrix metalloproteinases (MMPs) participate in physiological remodeling of the extracellular matrix. Recently we determined that both fibrinogen (Fg) and cross-linked fibrin (XL-Fb) are substrates for selected MMPs. Specifically, XL-Fb clots were solubilized by MMP-3 (stromelysin 1) by cleavage at gamma Gly 404-Ala 405, resulting in a D-like monomer fragment. Similarly, MMP-7 (matrilysin) and MT1-MMP (membrane type 1 matrix metalloproteinase) solubilized XL-Fb clots. However, the molecular mass of fragment D-dimer, obtained after MMP-7 and MT1-MMP degradation of XL-Fb, is similar to that of fragment D-dimer from plasmin degradation ( approximately 186 kDa). In contrast, fragment D-like monomer, from MMP-3 degradation of both fibrinogen (Fg) and XL-Fb, is similar to fragment D from plasmin degradation of Fg ( approximately 94 kDa). Reduced chains from MMP-3, MMP-7, and MT1-MMP digests of Fg and XL-Fb were subjected to direct sequence analyses and D/D-dimer alpha-chain showed cleavage at both alpha Asp 97-Phe 98 and alpha Asn 102-Asn 103. Degradation of the beta-chain resulted in microheterogeneity of cleavage sites at beta Asp 123-Leu 124, beta Asn 137-Val 138, and beta Glu 141-Tyr 142, whereas all three enzymes cleaved the gamma-chain at gamma Thr 83-Leu 84. In both Fg and XL-Fb, several cleavage sites obtained by proteolysis with MMP-3, MMP-7, and MT1-MMP were found to be in very close proximity to those obtained by plasmin on these same substrates. That does not occur with other MMPs such as MMP-1, -2, and -9 and MT2-MMP. The degradation of XL-Fb by MMPs suggests both plasmin-dependent and independent mechanisms of fibrinolysis that might be relevant in inflammation, angiogenesis, arthritis, and atherosclerosis.

Binding Sites↗
PubMed1976

Amino-acid sequence of fragment A, an enzymically active fragment from diphtheria toxin.

The amino-acid sequence of Fragment A from diphtheria toxin is reported. Fragment A (molecular weight, Mr, 21,145) is the major enzymically active fragment produced upon activation of the intact toxin (Mr about 60,000) by limited tryptic digestion and reduction. It, or a similar fragment, is believed responsible for the inhibition of protein synthesis in animal cells exposed to the toxin. Fragment A, which corresponds to the amino terminus of the toxin, is shown here to consist of three major forms (190, 192, and 193 residues) resulting from cleavage by trypsin adjacent to any of three closely spaced arginine residues. All three forms are enzymically active.

Amino Acid Sequence↗
PubMed1998

Resistance to DNA fragmentation and chromatin condensation in mice lacking the DNA fragmentation factor 45.

The DNA fragmentation factor 45 (DFF45) is a subunit of a heterodimeric nuclease complex critical for the induction of DNA fragmentation in vitro. To understand the in vivo role of DFF45 in programmed cell death, we generated DFF45 mutant mice. DNA fragmentation activity is completely abolished in cell extracts from DFF45 mutant tissues. In response to apoptotic stimuli, splenocytes, thymocytes, and granulocytes from DFF45 mutant mice are resistant to DNA fragmentation, and splenocytes and thymocytes are also resistant to chromatin condensation. Nevertheless, development of the immune system in the DFF45 mutant mice is normal. These results demonstrate that DFF45 is critical for the induction of DNA fragmentation and chromatin condensation in vivo, but is not required for normal immune system development.

Animals↗