Further considerations on the intranuclear distribution of HMGI/Y proteins.
We have investigated the intranuclear distribution of High-mobility group proteins I/Y by means of immunofluorescent staining employing a variety of cell lines. Confocal scanning laser microscopy analysis revealed that High-mobility group proteins I/Y are present in an intranuclear fibrogranular network and mitotic chromosomes. In Caski, C4I, Flow 2002, and K562 cell lines, High-mobility group proteins I/Y were absent from nucleoli, whereas in HeLa cells they were present in this nuclear domain. Double immunolabeling studies showed that High-mobility group proteins I/Y co-localize with other key nuclear components such as NuMA, SC-35, and TAF(II)70. Nuclear reactivity for High-mobility group proteins I/Y dramatically decreased in apoptotic nuclei of HL-60 human leukemia cells. Our morphological data correlate well with previous biochemical and functional findings obtained by other investigators, who have demonstrated multiple roles for this class of polypeptides. However, they point to the likelihood that High-mobility group proteins I/Y are involved in as yet unidentified functions, most likely in the speckle domains of the nucleus. They also show that conceivably these proteins are also involved in apoptosis.
Tabellini
G
G
Dipartimento di Morfologia Umana Normale, Università di Trieste, Italy.
Riccio
M
M
Baldini
G
G
Bareggi
R
R
Billi
A M
AM
Grill
V
V
Narducci
P
P
Martelli
A M
AM
D034961:Antigens, Nuclear; D017209:Apoptosis / Q000235:genetics*; D002451:Cell Compartmentation / Q000235:genetics*; D018797:Cell Cycle Proteins; D002466:Cell Nucleolus / Q000378:metabolism; D002467:Cell Nucleus / Q000378:metabolism* / Q000648:ultrastructure*; D002875:Chromosomes / Q000378:metabolism; D005260:Female; D005455:Fluorescent Antibody Technique; D005456:Fluorescent Dyes; D025741:HMGA1a Protein / Q000235:genetics / Q000378:metabolism*; D006367:HeLa Cells; D006801:Humans; D007211:Indoles; D018613:Microscopy, Confocal; D034521:Nuclear Matrix-Associated Proteins; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism; D012261:Ribonucleoproteins; D000068103:Serine-Arginine Splicing Factors; D035381:TATA-Binding Protein Associated Factors; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism; D014158:Transcription, Genetic / Q000235:genetics*
D034961:Antigens, Nuclear; D018797:Cell Cycle Proteins; D005456:Fluorescent Dyes; D007211:Indoles; C050045:NUMA1 protein, human; D034521:Nuclear Matrix-Associated Proteins; D009687:Nuclear Proteins; D012261:Ribonucleoproteins; C084977:TAF6 protein, human; D035381:TATA-Binding Protein Associated Factors; D014157:Transcription Factors; D025741:HMGA1a Protein; C073288:SRSF2 protein, human; D000068103:Serine-Arginine Splicing Factors; C007293:DAPI