Cbl-b mitigates the responsiveness of naive CD8+ T cells that experience extensive tonic T cell receptor signaling.

Naive T cells experience tonic T cell receptor (TCR) signaling in response to self-antigens presented by major histocompatibility complex (MHC) in secondary lymphoid organs. We investigated how relatively weak or strong tonic TCR signals influence naive CD8+ T cell responses to stimulation with foreign antigens. The heterogeneous expression of Nur77-GFP, a transgenic reporter of tonic TCR signaling, in naive CD8+ T cells suggests variable intensities or durations of tonic TCR signaling. Although the expression of genes associated with acutely stimulated T cells was increased in Nur77-GFPHI cells, these cells were hyporesponsive to agonist TCR stimulation compared with Nur77-GFPLO cells. This hyporesponsiveness manifested as diminished activation marker expression and decreased secretion of IFN-γ and IL-2. The protein abundance of the ubiquitin ligase Cbl-b, a negative regulator of TCR signaling, was greater in Nur77-GFPHI cells than in Nur77-GFPLO cells, and Cbl-b deficiency partially restored the responsiveness of Nur77-GFPHI cells. Our data suggest that the cumulative effects of previously experienced tonic TCR signaling recalibrate naive CD8+ T cell responsiveness. These changes include gene expression changes and negative regulation partially dependent on Cbl-b. This cell-intrinsic negative feedback loop may enable the immune system to restrain naive CD8+ T cells with higher self-reactivity.

Accumulation of TCR signaling from self-antigens in naive CD8 T cells mitigates early responsiveness.

The cumulative effects of T cell receptor (TCR) signal transduction over extended periods of time influences T cell biology, such as the positive selection of immature thymocytes or the proliferative responses of naive T cells. Naive T cells experience recurrent TCR signaling in response to self-antigens in the steady state. However, how these signals influence the responsiveness of naive CD8+ T cells to subsequent agonist TCR stimulation remains incompletely understood. We investigated how naive CD8+ T cells that experienced relatively low or high levels of TCR signaling in response to self-antigens respond to stimulation with foreign antigens. A transcriptional reporter of Nr4a1 (Nur77-GFP) revealed substantial heterogeneity of the amount of TCR signaling naive CD8+ T cells accumulate in the steady state. Nur77-GFPHI cells exhibited diminished T cell activation and secretion of IFNγ and IL-2 relative to Nur77-GFPLO cells in response to agonist TCR stimulation. Differential gene expression analyses revealed upregulation of genes associated with acutely stimulated T cells in Nur77-GFPHI cells but also increased expression of negative regulators such as the phosphatase Sts1. Responsiveness of Nur77-GFPHI cells to TCR stimulation was partially restored at the level of IFNγ secretion by deficiency of Sts1 or the ubiquitin ligase Cbl-b. Our data suggest that extensive accumulation of TCR signaling during steady state conditions induces a recalibration of the responsiveness of naive CD8+ T cells through gene expression changes and negative regulation, at least in part, dependent on Sts1 and Cbl-b. This cell-intrinsic negative feedback loop may allow the immune system to limit the autoreactive potential of highly self-reactive naive CD8+ T cells.

Strong Basal/Tonic TCR Signals Are Associated with Negative Regulation of Naive CD4+ T Cells.

T cells experience varying intensities of tonic or basal TCR signaling in response to self-peptides presented by MHC (self-pMHC) in vivo. We analyzed four subpopulations of mouse naive CD4+ cells that express different levels of Nur77-GFP and Ly6C, surrogate markers that positively and inversely correlate with the strength of tonic TCR signaling, respectively. Adoptive transfer studies suggest that relatively weak or strong Nur77-GFP intensity in thymocytes tends to be maintained in mature T cells. Two-dimensional affinity measurements were lowest for Nur77-GFPloLy6C+ cells and highest for Nur77-GFPhiLy6C- cells, highlighting a positive correlation between apparent TCR affinity and tonic TCR signal strength. Despite experiencing the strongest tonic TCR signaling, Nur77-GFPhiLy6C- cells were least responsive to multiple concentrations of a cognate or suboptimal pMHC. Gene expression analyses suggest that Nur77-GFPhiLy6C- cells induce a gene expression program that has similarities with that of acutely stimulated T cells. However, strong tonic TCR signaling also correlates with increased expression of genes with inhibitory functions, including coinhibitory receptors. Similarly, assay for transposase-accessible chromatin with sequencing analyses suggested that increased tonic TCR signal strength correlated with increased chromatin accessibility associated with genes that have positive and inhibitory roles in T cell activation. Strikingly, Nur77-GFPhiLy6C- cells exhibited differential accessibility within regions of Cd200r1 and Tox that were similar in location to differentially accessible regions previously identified in exhausted CD8+ T cells. We propose that constitutive strong tonic TCR signaling triggers adaptations detectable at both the transcriptional and epigenetic levels, ultimately contributing to the tuning of T cell responsiveness.

A supergene-linked estrogen receptor drives alternative phenotypes in a polymorphic songbird.

Behavioral evolution relies on genetic changes, yet few behaviors can be traced to specific genetic sequences in vertebrates. Here we provide experimental evidence showing that differentiation of a single gene has contributed to the evolution of divergent behavioral phenotypes in the white-throated sparrow, a common backyard songbird. In this species, a series of chromosomal inversions has formed a supergene that segregates with an aggressive phenotype. The supergene has captured ESR1, the gene that encodes estrogen receptor α (ERα); as a result, this gene is accumulating changes that now distinguish the supergene allele from the standard allele. Our results show that in birds of the more aggressive phenotype, ERα knockdown caused a phenotypic change to that of the less aggressive phenotype. We next showed that in a free-living population, aggression is predicted by allelic imbalance favoring the supergene allele. Finally, we identified cis-regulatory features, both genetic and epigenetic, that explain the allelic imbalance. This work provides a rare illustration of how genotypic divergence has led to behavioral phenotypic divergence in a vertebrate.

Adaptation by naïve CD4+ T cells to self-antigen-dependent TCR signaling induces functional heterogeneity and tolerance.

Naïve CD4+ T cells experience weak T cell receptor (TCR) signals induced by self-peptides presented by MHC II. To investigate how these "basal" TCR signals influence responses to agonist TCR ligand stimulation, we analyzed naïve CD4+ cells expressing varying amounts of CD5, Ly6C, and Nur77-GFP, markers that reflect the strength of basal TCR signaling. Phenotypic analyses indicate that the broadest range of basal TCR signal strength can be visualized by a combination of Nur77-GFP and Ly6C. A range of basal TCR signaling is detectable even in populations that express identical TCRs. Whereas moderate basal TCR signal strength correlates with higher IL-2 secretion at early time points following TCR stimulation, weak basal TCR signaling correlated with higher IL-2 secretion at later time points. We identify a population of Nur77-GFPHI Ly6C- cells that could not be reliably marked by either of CD5, Ly6C, or Nur77-GFP alone. These cells experience the strongest basal TCR signaling, consistently produce less IL-2, and express PD-1 and markers associated with anergy, such as Grail and Cbl-b. We propose that adaptation to the strength of basal TCR signaling drives the phenotypic and functional heterogeneity of naïve CD4+ cells.

Rapid regulatory evolution of a nonrecombining autosome linked to divergent behavioral phenotypes.

In the white-throated sparrow (Zonotrichia albicollis), the second chromosome bears a striking resemblance to sex chromosomes. First, within each breeding pair of birds, one bird is homozygous for the standard arrangement of the chromosome (ZAL2/ZAL2) and its mate is heterozygous for a different version (ZAL2/ZAL2m). Second, recombination is profoundly suppressed between the two versions, leading to genetic differentiation between them. Third, the ZAL2m version is linked with phenotypic traits, such as bright plumage, high aggression, and low parental behavior, which are usually associated with males. These similarities to sex chromosomes suggest that the evolutionary mechanisms that shape sex chromosomes, in particular genetic degeneration of the heterogametic version due to the suppression of recombination, are likely important in this system as well. Here, we investigated patterns of protein sequence evolution and gene expression evolution between the ZAL2 and ZAL2m chromosomes by whole-genome sequencing and transcriptome analyses. Patterns of protein evolution exhibited only weak signals of genetic degeneration, and few genes harbored signatures of positive selection. We found substantial evidence of transcriptome evolution, such as significant expression divergence between ZAL2 and ZAL2m alleles and signatures of dosage compensation for highly expressed genes. These results suggest that, early in the evolution of heteromorphic chromosomes, gene expression divergence and dosage compensation can prevail before large-scale genetic degeneration. Our results show further that suppression of recombination between heteromorphic chromosomes can lead to the evolution of alternative (sex-like) behavioral phenotypes before substantial genetic degeneration.

Long-term breast cancer risk following ovarian stimulation in young egg donors: a call for follow-up, research and informed consent.

In the USA and other countries, oocyte donation is gaining increasing importance. Although sufficient data exist on procedure-associated short-term risks for oocyte donors, such as ovarian hyperstimulation syndrome, long-term follow-up studies of egg donors are lacking and their health risks are unknown. The lack of information may be misleadingly interpreted as lack of risk. Long-term hormone replacement therapy is recognized as a risk factor for breast cancer; the breast cancer risk of ovarian stimulation for egg donors is unknown but is a possibility. This commentary describes five individual cases of egg donors who developed breast cancer (four out of five women in their 30s) despite negative genetic testing results. Additionally, we summarize available studies of breast cancer in infertile women who experienced IVF. We emphasize the need to create egg donor registries that will facilitate long-term studies on egg donors. Until this information is available, we call for more realistic explanations to egg donors about the lack of knowledge of long-term risks as well as more transparent informed consent documents.

Adolescents Conceived through Donor Insemination in Mother-Headed Families: A Qualitative Study of Motivations and Experiences of Contacting and Meeting Same-donor Offspring.

This study interviewed adolescents conceived using sperm donation to examine their experiences of contacting and meeting 'same-donor offspring' (i.e. donor-conceived offspring raised in different families who share the same donor), their motivations for this contact, and how they make meaning of these relationships. This in-depth qualitative study involved semi-structured interviews with 23 young people aged 12-19 years (mean = 14 years). Interviewees were motivated by curiosity about their biological relations and by wanting to extend their family. Contact with same-donor offspring was described as being either normal/neutral or as a unique experience that was integrated into their identity. This study highlights the importance of contact between same donor offspring, particularly during adolescence, a developmental stage associated with identity formation. The findings have important policy implications as they suggest that donor-conceived individuals may benefit from contact with others conceived using the same donor prior to the age of 18 years.

Gamete donor anonymity and limits on numbers of offspring: the views of three stakeholders.

This paper discusses the attitudes of three groups of stakeholders in the world of assisted reproduction gamete donors, parents who use donated gamete, and offspring conceived with donated gametes with respect to the two issues of donor anonymity and limits on the number of offspring a single donor can produce. The data are drawn from on-line surveys which were made available between May 12, 2104 and August 15, 2014 to gamete donors, donor-conceived offspring, and parents who used donated gametes to conceive. A total of 325 donors (176 egg donors; 149 sperm donors) responded to the survey as did 2134 parents and 419 offspring. The data show that offspring are more opposed to donor anonymity than are parents and donors. Among offspring opposition to anonymity grows as they age. On the other hand, parents are most in favor of limits on numbers of offspring produced by a single donor. Parents worry about health and accidental contact between people conceived from the same donor.

Integrating donor conception into identity development: adolescents in fatherless families.

OBJECTIVE: To study the processes by which donor-conceived children incorporate donor conception into their subjective sense of identity. DESIGN: Cross-sectional. SETTING: Family homes. PATIENT(S): Nineteen donor-conceived adolescents. INTERVENTION(S): Administration of an interview and questionnaire. MAIN OUTCOME MEASURE(S): The mother-child relationship was assessed through the Friends and Family Interview, a semistructured interview designed to assess adolescents' security of attachment in terms of secure-autonomous, insecure-dismissive, insecure-preoccupied, and insecure-disorganized attachment patterns. The Donor Conception Identity Questionnaire assessed adolescents' thoughts and feelings about donor conception, yielding two factors: [1] curiosity about donor conception and [2] avoidance of donor conception. RESULT(S): Statistically significant associations were found between the Curiosity scale and the secure-autonomous and insecure-dismissing attachment ratings. Adolescents with secure-autonomous attachment patterns were more interested in exploring donor conception whereas those with insecure-dismissing patterns were less likely to express curiosity. Insecure-disorganized attachment ratings were statistically significantly correlated with the Avoidance scale, indicating higher levels of negative feelings about donor conception. CONCLUSION(S): The results of this study of the influence of parent-child relationships on thoughts and feelings about donor conception in adolescence suggest that the valence of the parent-child relationship influences adolescents' appraisal of their donor conception within the context of their growing sense of identity.

Gendering gametes: The unequal contributions of sperm and egg donors.

This paper compares three groups of gestational mothers who relied on gametes from donors they did not know. The three groups are women who have conceived with donor sperm and their own eggs, women who have conceived with donor eggs and a partner's sperm, and women who have conceived with embryos composed of both donor eggs and donor sperm. The paper explores three issues. First, it considers whether intending parents select sperm and egg donors for different attributes both when they are chosen as the only donor and when they are chosen as donors contributing to an entire embryo. Second, it examines how women imagine the donor. Finally, it looks at how women conceptualize the donor as an individual who contributes to their child's characteristics. Two significant findings emerged in this analysis of survey data. First, the data show that gametes are gendered with different attributes both when those gametes are separate and even more so when seen as complementary parts of a whole. Second, the data show that women minimize the impact of the egg donor (both when a sole contribution and especially when part of the complementary whole) and thus ignore the influence or impact of the egg donor relative to how they make sense of the influence or impact of the sperm donor. The data for this study comes from an online survey developed by the authors.

Estrogen Receptor Alpha as a Mediator of Life-History Trade-offs.

Trade-offs between competitive and parental strategies often are mediated by sex steroids. The mechanisms underlying steroid signaling and metabolism may therefore serve as targets of disruptive selection that leads to alternative behavioral phenotypes. White-throated sparrows exhibit two color morphs that differ in both competitive and parental behavior; white-striped (WS) birds engage in more territorial singing, whereas tan-striped (TS) birds provision nestlings more often. Although WS birds have higher levels of plasma testosterone (T) and estradiol than do TS birds, experimental equalization of these hormones does not abolish morph differences in singing. Neural sensitivity to sex steroids may differ between the morphs because the gene for estrogen receptor alpha (ERα) has been captured by a chromosomal rearrangement found only in the WS birds. We recently showed that expression of this gene differs between the morphs and may drive the behavioral polymorphism. First, the ERα promoter region contains fixed polymorphisms that affect transcription efficiency in vitro. Second, in a free-living population, local expression of ERα depends strongly on morph and predicts both territorial singing and parental provisioning. Differential ERα expression is particularly striking in the medial amygdala; WS birds have three times more ERα mRNA than do TS birds. This difference persists during the non-breeding season and is unaffected by exogenous T treatment. Finally, preliminary data generated by RNA-seq confirm that ERα expression in MeA is both differentially expressed and correlated with territorial singing. Together, these results suggest that ERα may be a target of disruptive selection that leads to alternative behavioral strategies. Our future directions include a more detailed analysis of the ERα promoter regions to determine the molecular basis of differential expression as well as gene network analyses to identify genes connected to ERα.

Emerging models for facilitating contact between people genetically related through donor conception: a preliminary analysis and discussion.

Previous research indicates interest among some donor-conceived people, donors and recipient parents in having contact. Outcomes of such contact appear largely, but not universally, positive. This paper seeks to understand better the characteristics of associated support services. Information gathered using the authors' direct experiences and professional and personal networks in different parts of the world indicates the emergence of four main groupings: (i) publically funded services outside of treatment centers; (ii) services provided by fertility treatment or gamete bank services; (iii) services provided privately by independent psychosocial or legal practitioners; and (4) services organized by offspring and/or recipient parents. Key operational features examined were: (i) who can access such services and when; (ii) what professional standards and funding are in place to provide them; and (iii) how 'matching' and contact processes are managed. Differences appear influenced variously by the needs of those directly affected, local policies, national legislation and the interests of the fertility services which recruit gamete donors and/or deliver donor conception treatments. The paper is intended to inform fuller debate about how best to meet the needs of those seeking information and contact, the implications for the way that fertility treatment and gametes donation services are currently provided and future research needs.

Evaluation of reference genes for quantitative real-time PCR in the brain, pituitary, and gonads of songbirds.

Quantitative real-time PCR (qPCR) is becoming a popular tool for the quantification of gene expression in the brain and endocrine tissues of songbirds. Accurate analysis of qPCR data relies on the selection of appropriate reference genes for normalization, yet few papers on songbirds contain evidence of reference gene validation. Here, we evaluated the expression of ten potential reference genes (18S, ACTB, GAPDH, HMBS, HPRT, PPIA, RPL4, RPL32, TFRC, and UBC) in brain, pituitary, ovary, and testis in two species of songbirds: zebra finch and white-throated sparrow. We used two algorithms, geNorm and NormFinder, to assess the stability of these reference genes in our samples. We found that the suitability of some of the most popular reference genes for target gene normalization in mammals, such as 18S, depended highly on tissue type. Thus, they are not the best choices for brain and gonad in these songbirds. In contrast, we identified alternative genes, such as HPRT, RPL4 and PPIA, that were highly stable in brain, pituitary, and gonad in these species. Our results suggest that the validation of reference genes in mammals does not necessarily extrapolate to other taxonomic groups. For researchers wishing to identify and evaluate suitable reference genes for qPCR in songbirds, our results should serve as a starting point and should help increase the power and utility of songbird models in behavioral neuroendocrinology.

Estrogen receptor α polymorphism in a species with alternative behavioral phenotypes.

The evolution of behavior relies on changes at the level of the genome; yet the ability to attribute a behavioral change to a specific, naturally occurring genetic change is rare in vertebrates. In the white-throated sparrow (Zonotrichia albicollis), a chromosomal polymorphism (ZAL2/2(m)) is known to segregate with a behavioral phenotype. Individuals with the ZAL2(m) haplotype engage in more territorial aggression and less parental behavior than individuals without it. These behaviors are thought to be mediated by sensitivity to sex steroids, and the chromosomal rearrangement underlying the polymorphism has captured a prime candidate gene: estrogen receptor 1 (ESR1), which encodes estrogen receptor α (ERα). We therefore hypothesized that the behavioral effects of the ZAL2(m) rearrangement are mediated by polymorphism in ESR1. We report here that (i) the ESR1 promoter region contains fixed polymorphisms distinguishing the ZAL2(m) and ZAL2 alleles; (ii); those polymorphisms regulate transcription efficiency in vitro and therefore potentially do the same in vivo (iii); the local expression of ERα in the brain depends strongly on genotype in a free-living population; and (iv) ERα expression in the medial amygdala and medial preoptic area may fully mediate the effects of genotype on territorial aggression and parenting, respectively. Thus, our study provides a rare glimpse of how a chromosomal polymorphism has affected the brain and social behavior in a vertebrate. Our results suggest that in this species, differentiation of ESR1 has played a causal role in the evolution of phenotypes with alternative life-history strategies.

A survey of 1700 women who formed their families using donor spermatozoa.

This paper reports the results of an online survey of 1700 recipients of donor spermatozoa conducted by the Donor Sibling Registry, aiming to understand the perspectives of respondents who had used donor spermatozoa. The survey examined: choice of sperm bank and donor; reporting of births and genetic disorders; disclosure; contact with donor and half-siblings; regulation of sperm donor activity and genetic testing; and access to medical information. The respondents formed three groups: single women; women in a same-sex relationship; and women in a heterosexual relationship. Some differences between the three cohorts were observed: preinsemination counselling; acceptance of donors without medical records or with chronic or late-onset diseases; awareness of choice of bank and type of donor; and views on the right of offspring to know their genetic origins. However, important areas of common ground were identified: the wish by those who had used an anonymous donor that they had used an open-identity donor; support for, and willingness to pay for, comprehensive genetic testing of donors; and desire for access to their donor's family health information. The implications of these results for policies concerning the use and management of donor spermatozoa will be discussed. This paper reports the results of a survey of 1700 women who used donor spermatozoa to conceive a child. The survey considers their views on the following areas: choice of sperm bank and donor; reporting of births and genetic disorders; disclosure; contact with donor and half-siblings; regulation of sperm donor activity and genetic testing; and access to medical information. This was an online survey was designed and conducted by the Donor Sibling Registry (DSR), a US-based non-profit organization that supports donor sperm recipients, donors and donor-conceived people. The survey aimed to understand the experiences, perspectives and concerns of women who had used donor spermatozoa. The respondents formed three groups: single women; women in a same sex relationship; and women in a heterosexual relationship. Some differences between the three groups were observed: preinsemination counselling; acceptance of donors without medical records or with chronic or late-onset diseases; awareness of choice of bank and type of donor; and the right of offspring to know their genetic origins. However, despite these differences, important areas of common ground were identified: the wish by those who had used an anonymous donor that they had used an open-identity donor; support for, and a willingness to pay for, comprehensive genetic testing of donors; and desire for access to their donor's family health information. The implications of these results for policies concerning the use and management of donor spermatozoa will be discussed.

Donor conceived offspring conceive of the donor: the relevance of age, awareness, and family form.

Rarely have donor conceived offspring been studied. Recently, it has become more common for parents to disclose the nature of conception to their offspring. This new development raises questions about the donor's place in the offspring's life and identity. Using surveys collected by the Donor Sibling Registry, the largest U.S. web-based registry, during a 15 week period from October 2009 to January 2010, we found that donor offspring view the donor as a whole person, rather than as simple genetic material (he can know you; he has looks; he can teach you about yourself); they also believe that the donor should act on his humanity (he should know about you and not remain an anonymous genetic contributor). Other new issues that emerge from this research include the findings that offspring may want to control the decision about contacting their sperm donor in order to facilitate a bond between themselves and the donor that is separate from their relationship with their parents. They also wish to assure their parents that their natal families are primary and will not be disrupted. We discuss how the age at which offspring learned about their donor conception and their current age each make a difference in their responses to what they want from contact with their donor. Family form (heterosexual two-parent families and lesbian two-parent families) also affects donor terminology. The role of the genetic father is reconsidered in both types of families. Donor conceived offspring raised in heterosexual families discover that their natal father no longer carries biological information and he is relegated to being "only" a social father. Offspring raised by lesbian couples experience a dissipation of the family narrative that they have no father. The donor, an imagined father, offers clues to the offspring's personal identity. The natal family is no longer the sole keeper of identity or ancestry.

Perspectives, experiences, and choices of parents of children conceived following oocyte donation.

This paper reports on and discusses the findings of an online survey initiated by the Donor Sibling Registry of 108 parents of children conceived following oocyte donation. Respondents generally supported early disclosure of donor conception to the child, although some bias in favour of disclosure cannot be excluded, given the recruitment source. Even so, extensive uncertainty regarding the optimum time for disclosure was evident. Around half of the parents who had either expressly chosen (50.0%), or had been given no choice of, an anonymous donor (54.1%) subsequently wished they had used an open-identity donor. A total of 87% of respondents showed interest in identifying and making contact with their donor and with other families containing children sharing the same donor, and 19% had already made such contact. The survey revealed considerable variations in respondents' experiences of clinic practices regarding the availability of counselling, information provided about choice of donor type, advice regarding disclosure and the reporting of births, indicating keys areas for improved professional practice. This paper reports on and discusses the findings of an online survey initiated by the Donor Sibling Registry of 108 parents of children conceived following ooctye donation. Respondents generally supported early disclosure of donor conception to the child, although extensive uncertainty regarding the optimum time for disclosure was evident. Around half of the parents who had either expressly chosen, or had been given no choice of, an anonymous donor subsequently wished they had used an open identity donor. A number of respondents showed interest in identifying and making contact with their donor and with other families containing children sharing the same donor, and a minority had already made such contact. The survey revealed considerable variations in respondents' experiences of clinic practices regarding the availability of counselling, information provided about choice of donor type, advice regarding disclosure and the reporting of births, indicating keys areas for improved professional practice.

ZBTB32 is an early repressor of the CIITA and MHC class II gene expression during B cell differentiation to plasma cells.

CIITA and MHC class II expression is silenced during the differentiation of B cells to plasma cells. When B cell differentiation is carried out ex vivo, CIITA silencing occurs rapidly, but the factors contributing to this event are not known. ZBTB32, also known as repressor of GATA3, was identified as an early repressor of CIITA in an ex vivo plasma cell differentiation model. ZBTB32 activity occurred at a time when B lymphocyte-induced maturation protein-1 (Blimp-1), the regulator of plasma cell fate and suppressor of CIITA, was minimally induced. Ectopic expression of ZBTB32 suppressed CIITA and I-A gene expression in B cells. Short hairpin RNA depletion of ZBTB32 in a plasma cell line resulted in re-expression of CIITA and I-A. Compared with conditional Blimp-1 knockout and wild-type B cells, B cells from ZBTB32/ROG-knockout mice displayed delayed kinetics in silencing CIITA during ex vivo plasma cell differentiation. ZBTB32 was found to bind to the CIITA gene, suggesting that ZBTB32 directly regulates CIITA. Lastly, ZBTB32 and Blimp-1 coimmunoprecipitated, suggesting that the two repressors may ultimately function together to silence CIITA expression. These results introduce ZBTB32 as a novel regulator of MHC-II gene expression and a potential regulatory partner of Blimp-1 in repressing gene expression.