Limits...
IkappaB kinase alpha is essential for mature B cell development and function.

Kaisho T, Takeda K, Tsujimura T, Kawai T, Nomura F, Terada N, Akira S - J. Exp. Med. (2001)

Bottom Line: Histologically, they also manifested marked disruption of germinal center formation and splenic microarchitectures that depend on mature B cells.IKKalpha(-/-) B cells not only showed impairment of survival and mitogenic responses in vitro, accompanied by decreased, although inducible, NF-kappaB activity, but also increased turnover rate in vivo.Taken together, these results demonstrate that IKKalpha is critically involved in the prevention of cell death and functional development of mature B cells.

View Article: PubMed Central - PubMed

Affiliation: Department of Host Defense, Research Institute for Microbial Diseases, Osaka University, Osaka 565-0871, Japan.

ABSTRACT
IkappaB kinase (IKK) alpha and beta phosphorylate IkappaB proteins and activate the transcription factor, nuclear factor (NF)-kappaB. Although both are highly homologous kinases, gene targeting experiments revealed their differential roles in vivo. IKKalpha is involved in skin and limb morphogenesis, whereas IKKbeta is essential for cytokine signaling. To elucidate in vivo roles of IKKalpha in hematopoietic cells, we have generated bone marrow chimeras by transferring control and IKKalpha-deficient fetal liver cells. The mature B cell population was decreased in IKKalpha(-/-) chimeras. IKKalpha(-/-) chimeras also exhibited a decrease of serum immunoglobulin basal level and impaired antigen-specific immune responses. Histologically, they also manifested marked disruption of germinal center formation and splenic microarchitectures that depend on mature B cells. IKKalpha(-/-) B cells not only showed impairment of survival and mitogenic responses in vitro, accompanied by decreased, although inducible, NF-kappaB activity, but also increased turnover rate in vivo. In addition, transgene expression of bcl-2 could only partially rescue impaired B cell development in IKKalpha(-/-) chimeras. Taken together, these results demonstrate that IKKalpha is critically involved in the prevention of cell death and functional development of mature B cells.

Show MeSH

Related in: MedlinePlus

Impaired survival in vitro and increased turnover in vivo of IKKα2/− B cells. (A and B) PB and splenocytes from IKKα1/+ and IKKα2/− RAG2-deficient B6 chimeras were cultured in complete RPMI 1640 in the absence or presence of mitogens for the indicated periods and stained with FITC–annexin V and PE-B220. Percentages of annexin+ B cells were calculated by dividing percentages of B220+annexin+ cells by those of total B (B220+annexin+ and B220+annexin−) cells and shown as bar graphs in B. (C) Increased B cell turnover in IKKα2/− chimeras. The turnover of splenic B cells was determined by BrdU incorporation. Numbers represent percentages of the quadrants. Experiments were independently performed three times with similar results. One representative experiment is shown.
© Copyright Policy
Related In: Results  -  Collection


getmorefigures.php?uid=PMC2195900&req=5

Figure 2: Impaired survival in vitro and increased turnover in vivo of IKKα2/− B cells. (A and B) PB and splenocytes from IKKα1/+ and IKKα2/− RAG2-deficient B6 chimeras were cultured in complete RPMI 1640 in the absence or presence of mitogens for the indicated periods and stained with FITC–annexin V and PE-B220. Percentages of annexin+ B cells were calculated by dividing percentages of B220+annexin+ cells by those of total B (B220+annexin+ and B220+annexin−) cells and shown as bar graphs in B. (C) Increased B cell turnover in IKKα2/− chimeras. The turnover of splenic B cells was determined by BrdU incorporation. Numbers represent percentages of the quadrants. Experiments were independently performed three times with similar results. One representative experiment is shown.

Mentions: NF-κB activity has been shown to mediate antiapoptotic activity in various cells including B cells 4142. We have examined survival of B lineage cells in both IKKα1/+ and IKKα2/− chimeras with annexin V binding activity. PB from the chimeras was cultured in vitro in the absence of mitogens for the indicated periods and analyzed for their annexin V binding activity with FACS® (Fig. 2A and Fig. B). Before culture (0 h), percentages of B220+annexin+ cells in PB were higher in IKKα2/− chimeras (3.3/7.1 + 3.3 = 31.7%) than in IKKα1/+ chimeras (4.3/4.3 + 26.2 = 14.1%) (Fig. 2A and Fig. B). B220+annexin+ cells reached >95% of the total B220+ cells in IKKα2/− chimeras after 24 h of culture, whereas they were 63.4 and 83.7% in IKKα1/+ chimeras after 24 and 48 h of culture, respectively. Likewise, survival of splenic B cells was severely impaired in IKKα2/− chimeras before and throughout the culture period (Fig. 2A and Fig. B).


IkappaB kinase alpha is essential for mature B cell development and function.

Kaisho T, Takeda K, Tsujimura T, Kawai T, Nomura F, Terada N, Akira S - J. Exp. Med. (2001)

Impaired survival in vitro and increased turnover in vivo of IKKα2/− B cells. (A and B) PB and splenocytes from IKKα1/+ and IKKα2/− RAG2-deficient B6 chimeras were cultured in complete RPMI 1640 in the absence or presence of mitogens for the indicated periods and stained with FITC–annexin V and PE-B220. Percentages of annexin+ B cells were calculated by dividing percentages of B220+annexin+ cells by those of total B (B220+annexin+ and B220+annexin−) cells and shown as bar graphs in B. (C) Increased B cell turnover in IKKα2/− chimeras. The turnover of splenic B cells was determined by BrdU incorporation. Numbers represent percentages of the quadrants. Experiments were independently performed three times with similar results. One representative experiment is shown.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2195900&req=5

Figure 2: Impaired survival in vitro and increased turnover in vivo of IKKα2/− B cells. (A and B) PB and splenocytes from IKKα1/+ and IKKα2/− RAG2-deficient B6 chimeras were cultured in complete RPMI 1640 in the absence or presence of mitogens for the indicated periods and stained with FITC–annexin V and PE-B220. Percentages of annexin+ B cells were calculated by dividing percentages of B220+annexin+ cells by those of total B (B220+annexin+ and B220+annexin−) cells and shown as bar graphs in B. (C) Increased B cell turnover in IKKα2/− chimeras. The turnover of splenic B cells was determined by BrdU incorporation. Numbers represent percentages of the quadrants. Experiments were independently performed three times with similar results. One representative experiment is shown.
Mentions: NF-κB activity has been shown to mediate antiapoptotic activity in various cells including B cells 4142. We have examined survival of B lineage cells in both IKKα1/+ and IKKα2/− chimeras with annexin V binding activity. PB from the chimeras was cultured in vitro in the absence of mitogens for the indicated periods and analyzed for their annexin V binding activity with FACS® (Fig. 2A and Fig. B). Before culture (0 h), percentages of B220+annexin+ cells in PB were higher in IKKα2/− chimeras (3.3/7.1 + 3.3 = 31.7%) than in IKKα1/+ chimeras (4.3/4.3 + 26.2 = 14.1%) (Fig. 2A and Fig. B). B220+annexin+ cells reached >95% of the total B220+ cells in IKKα2/− chimeras after 24 h of culture, whereas they were 63.4 and 83.7% in IKKα1/+ chimeras after 24 and 48 h of culture, respectively. Likewise, survival of splenic B cells was severely impaired in IKKα2/− chimeras before and throughout the culture period (Fig. 2A and Fig. B).

Bottom Line: Histologically, they also manifested marked disruption of germinal center formation and splenic microarchitectures that depend on mature B cells.IKKalpha(-/-) B cells not only showed impairment of survival and mitogenic responses in vitro, accompanied by decreased, although inducible, NF-kappaB activity, but also increased turnover rate in vivo.Taken together, these results demonstrate that IKKalpha is critically involved in the prevention of cell death and functional development of mature B cells.

View Article: PubMed Central - PubMed

Affiliation: Department of Host Defense, Research Institute for Microbial Diseases, Osaka University, Osaka 565-0871, Japan.

ABSTRACT
IkappaB kinase (IKK) alpha and beta phosphorylate IkappaB proteins and activate the transcription factor, nuclear factor (NF)-kappaB. Although both are highly homologous kinases, gene targeting experiments revealed their differential roles in vivo. IKKalpha is involved in skin and limb morphogenesis, whereas IKKbeta is essential for cytokine signaling. To elucidate in vivo roles of IKKalpha in hematopoietic cells, we have generated bone marrow chimeras by transferring control and IKKalpha-deficient fetal liver cells. The mature B cell population was decreased in IKKalpha(-/-) chimeras. IKKalpha(-/-) chimeras also exhibited a decrease of serum immunoglobulin basal level and impaired antigen-specific immune responses. Histologically, they also manifested marked disruption of germinal center formation and splenic microarchitectures that depend on mature B cells. IKKalpha(-/-) B cells not only showed impairment of survival and mitogenic responses in vitro, accompanied by decreased, although inducible, NF-kappaB activity, but also increased turnover rate in vivo. In addition, transgene expression of bcl-2 could only partially rescue impaired B cell development in IKKalpha(-/-) chimeras. Taken together, these results demonstrate that IKKalpha is critically involved in the prevention of cell death and functional development of mature B cells.

Show MeSH
Related in: MedlinePlus