The Zinc-finger protein ASCIZ regulates B cell development via DYNLL1 and Bim.
Developing B lymphocytes expressing defective or autoreactive pre-B or B cell receptors (BCRs) are eliminated by programmed cell death, but how the balance between death and survival signals is regulated to prevent immunodeficiency and autoimmunity remains incompletely understood. In this study, we show that absence of the essential ATM (ataxia telangiectasia mutated) substrate Chk2-interacting Zn(2+)-finger protein (ASCIZ; also known as ATMIN/ZNF822), a protein with dual functions in the DNA damage response and as a transcription factor, leads to progressive cell loss from the pre-B stage onwards and severely diminished splenic B cell numbers in mice. This lymphopenia cannot be suppressed by deletion of p53 or complementation with a prearranged BCR, indicating that it is not caused by impaired DNA damage responses or defective V(D)J recombination. Instead, ASCIZ-deficient B cell precursors contain highly reduced levels of DYNLL1 (dynein light chain 1; LC8), a recently identified transcriptional target of ASCIZ, and normal B cell development can be restored by ectopic Dynll1 expression. Remarkably, the B cell lymphopenia in the absence of ASCIZ can also be fully suppressed by deletion of the proapoptotic DYNLL1 target Bim. Our findings demonstrate a key role for ASCIZ in regulating the survival of developing B cells by activating DYNLL1 expression, which may then modulate Bim-dependent apoptosis.
St. Vincent's Institute of Medical Research, The University of Melbourne, Melbourne, Victoria 3052, Australia.
Sabine
S
Jurado
Kimberly
K
Gleeson
Kristy
K
O'Donnell
David J
DJ
Izon
Carl R
CR
Walkley
Andreas
A
Strasser
David M
DM
Tarlinton
Jörg
J
Heierhorst
D000818:Animals; D017209:Apoptosis / Q000235:genetics; D051017:Apoptosis Regulatory Proteins / Q000235:genetics / Q000378:metabolism*; D001402:B-Lymphocytes / Q000473:pathology / Q000502:physiology*; D000072224:Bcl-2-Like Protein 11; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism*; D056445:Cytoplasmic Dyneins; D004249:DNA Damage; D004398:Dyneins / Q000235:genetics / Q000378:metabolism*; D005786:Gene Expression Regulation; D008231:Lymphopenia / Q000235:genetics / Q000473:pathology; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism*; D011518:Proto-Oncogene Proteins / Q000235:genetics / Q000378:metabolism*; D014157:Transcription Factors; D060152:V(D)J Recombination
C554480:ATMIN protein, mouse; D051017:Apoptosis Regulatory Proteins; D000072224:Bcl-2-Like Protein 11; C000606776:Bcl2l11 protein, mouse; D002352:Carrier Proteins; D008565:Membrane Proteins; D009687:Nuclear Proteins; D011518:Proto-Oncogene Proteins; D014157:Transcription Factors; D056445:Cytoplasmic Dyneins; C576160:DYNLL1 protein, mouse; D004398:Dyneins