RESUMO
The single-minded 2 (SIM2) protein is a basic helix-loop-helix transcription factor regulating central nervous system (CNS) development in Drosophila. In humans, SIM2 is located within the Down syndrome critical region on chromosome 21 and may be involved in the development of mental retardation phenotype in Down syndrome. In this study, knockout of SIM2 expression in mice resulted in a gas distention phenotype in the gastrointestinal tract. We found that SIM2 is required for the expression of all cryptdins and numerous other antimicrobial peptides (AMPs) expressed in the small intestine. The mechanism underlying how SIM2 controls AMP expression involves both direct and indirect regulations. For the cryptdin genes, SIM2 regulates their expression by modulating transcription factor 7-like 2, a crucial regulator in the Wnt/ß-catenin signaling pathway, while for other AMP genes, such as RegIIIγ, SIM2 directly activates their promoter activity. Our results establish that SIM2 is a crucial regulator in controlling expression of intestinal AMPs to maintain intestinal innate immunity against microbes.
Assuntos
Fatores de Transcrição Hélice-Alça-Hélice Básicos/fisiologia , Imunidade Inata/genética , Intestino Delgado/imunologia , Fosfatase Alcalina/metabolismo , Animais , Peptídeos Catiônicos Antimicrobianos/metabolismo , Fatores de Transcrição Hélice-Alça-Hélice Básicos/genética , Contagem de Células , Feminino , Esvaziamento Gástrico/genética , Esvaziamento Gástrico/fisiologia , Trato Gastrointestinal/metabolismo , Trato Gastrointestinal/patologia , Técnicas In Vitro , Absorção Intestinal/genética , Absorção Intestinal/fisiologia , Intestino Delgado/patologia , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Peristaltismo/genética , Peristaltismo/fisiologiaRESUMO
Sexual conflict over mating is costly to female physiology. Caenorhabditis elegans hermaphrodites generally produce self-progeny, but they can produce cross-progeny upon successfully mating with a male. We have uncovered that C. elegans hermaphrodites experience sexual conflict over mating, resulting in severe costs in terms of their fertility and longevity. We show that reactive oxygen species (ROS) accumulate on the apical surfaces of spermathecal bag cells after successful mating and induce cell damage, leading to ovulation defects and fertility suppression. To counteract these negative impacts, C. elegans hermaphrodites deploy the octopamine (OA) regulatory pathway to enhance glutathione (GSH) biosynthesis and protect spermathecae from mating-induced ROS. We show that the SER-3 receptor and mitogen-activated protein kinase (MAPK) KGB-1 cascade transduce the OA signal to transcription factor SKN-1/Nrf2 in the spermatheca to upregulate GSH biosynthesis.
RESUMO
To survive and reproduce, living organisms must evolve numerous mechanisms to re-adjust their physiology when encountering adverse conditions that subject them to severe stress. We found that short-term starvation (STS) stress in young adult male Caenorhabditis elegans can significantly improve their vitality (relative to nonstressed males) when they are aged. In addition, we found that stress-treated aged males maintained reproductive activity equivalent to young males, whereas nonstressed aged males quickly lost reproductive ability. STS stress can preserve sperm number and quality in aged male worms. Spermatogenesis involves germ cell mitosis and meiosis. We found that germ cell meiotic activity is more sensitive to aging than mitotic activity and is declining rapidly with age. We examined the role of numerous factors important for spermatogenesis on STS-preserved spermatogenesis during aging. Our results show that mutant strains deficient in anaphase-promoting complex/cyclosome (APC/C) function fail to exhibit the STS stress-enhanced spermatogenesis found in wild-type N2 worms, suggesting that the mechanism underlying starvation-induced spermatogenesis involves the APC/C complex, a conserved ubiquitin-protein ligase E3 complex. Furthermore, transgenic expression of FZY-1/CDC-20, a coactivator of APC/C, ameliorated the age-associated decline of meiosis, similar to the hormetic effect of STS.
Assuntos
Envelhecimento/genética , Caenorhabditis elegans/crescimento & desenvolvimento , Caenorhabditis elegans/genética , Células Germinativas/citologia , Meiose/genética , Espermatogênese/genética , Inanição/genética , Estresse Fisiológico/genética , Animais , Caenorhabditis elegans/citologia , Células Germinativas/metabolismo , MasculinoRESUMO
UNLABELLED: Glycine N-methyltransferase (GNMT) affects genetic stability by regulating DNA methylation and interacting with environmental carcinogens. To establish a Gnmt knockout mouse model, 2 lambda phage clones containing a mouse Gnmt genome were isolated. At 11 weeks of age, the Gnmt-/- mice had hepatomegaly, hypermethioninemia, and significantly higher levels of both serum alanine aminotransferase and hepatic S-adenosylmethionine. Such phenotypes mimic patients with congenital GNMT deficiencies. A real-time polymerase chain reaction analysis of 10 genes in the one-carbon metabolism pathway revealed that 5,10-methylenetetrahydrofolate reductase, S-adenosylhomocysteine hydrolase (Ahcy), and formiminotransferase cyclodeaminase (Ftcd) were significantly down-regulated in Gnmt-/- mice. This report demonstrates that GNMT regulates the expression of both Ftcd and Ahcy genes. Results from pathological examinations indicated that 57.1% (8 of 14) of the Gnmt-/- mice had glycogen storage disease (GSD) in their livers. Focal necrosis was observed in male Gnmt-/- livers, whereas degenerative changes were found in the intermediate zones of female Gnmt-/- livers. In addition, hypoglycemia, increased serum cholesterol, and significantly lower numbers of white blood cells, neutrophils, and monocytes were observed in the Gnmt-/- mice. A real-time polymerase chain reaction analysis of genes involved in the gluconeogenesis pathways revealed that the following genes were significantly down-regulated in Gnmt-/- mice: fructose 1,6-bisphosphatase, phosphoenolpyruvate carboxykinase, and glucose-6-phosphate transporter. CONCLUSION: Because Gnmt-/- mice phenotypes mimic those of patients with GNMT deficiencies and share several characteristics with GSD Ib patients, we suggest that they are useful for studies of the pathogenesis of congenital GNMT deficiencies and the role of GNMT in GSD and liver tumorigenesis.
Assuntos
Glicina N-Metiltransferase/metabolismo , Doença de Depósito de Glicogênio/metabolismo , Glicogênio/metabolismo , Hepatite Crônica/metabolismo , Fígado/metabolismo , ATPases Associadas a Diversas Atividades Celulares , Alanina Transaminase/sangue , Animais , Mapeamento Cromossômico , Modelos Animais de Doenças , Regulação para Baixo , Embrião de Mamíferos/metabolismo , Feminino , Expressão Gênica , Perfilação da Expressão Gênica , Homocisteína/sangue , Fígado/patologia , Metionina/sangue , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Reação em Cadeia da Polimerase , Proteínas/metabolismo , S-Adenosil-Homocisteína/metabolismo , S-Adenosilmetionina/metabolismoRESUMO
Mice deficient in hepatocyte nuclear factor 1 alpha (HNF-1alpha) develop dwarfism, liver dysfunction, and type 2 diabetes mellitus. Liver dysfunction in HNF-1alpha-null mice includes severe hepatic glycogen accumulation and dyslipidemia. The liver dysfunction may appear as soon as 2 weeks after birth. Since the HNF-1alpha-null mice become diabetic 2 weeks after birth, the early onset of the liver dysfunction is unlikely to be due to the diabetic status of the mice. More likely, it is due directly to the deficiency of HNF-1alpha in liver. Although the HNF-1alpha-null mice have an average life span of 1 year, the severe liver phenotype has thwarted attempts to study the pathogenesis of maturity-onset diabetes of the young type 3 (MODY3) and to examine therapeutic strategies for diabetes prevention and treatment in these mice. To circumvent this problem, we have generated a new Hnf-1alpha mutant mouse line, Hnf-1alpha(kin/kin), using gene targeting to inactivate the Hnf-1alpha gene and at the same time, to incorporate the Cre-loxP DNA recombination system into the locus for later revival of the Hnf-1alpha gene in tissues by tissue-specifically expressed Cre recombinase. The Hnf-1alpha(kin/kin) mice in which the expression of HNF-1alpha was inactivated in germ line cells were indistinguishable from the HNF-1alpha-null mice with regard to both the diabetes and liver phenotypes. Intriguingly, when the inactivated Hnf-1alpha gene was revived in liver (hepatic Hnf-1alpha revived) by the Cre recombinase driven by an albumin promoter, the Hnf-1alpha(kin/kin) mice, although severely diabetic, grew normally and did not develop any of the liver dysfunctions. In addition, we showed that the expression of numerous genes in pancreas, including a marker gene for pancreas injury, was affected by liver dysfunction but not by the deficiency of HNF-1alpha in pancreas. Thus, our hepatic-Hnf-1alpha-revived mice may serve as a useful mouse model to study the human MODY3 disorder.
Assuntos
Proteínas de Ligação a DNA , Diabetes Mellitus Tipo 2/etiologia , Fígado/fisiopatologia , Proteínas Nucleares , Fatores de Transcrição/deficiência , Fatores de Transcrição/genética , Alelos , Animais , Sequência de Bases , DNA/genética , Diabetes Mellitus Tipo 2/genética , Diabetes Mellitus Tipo 2/patologia , Diabetes Mellitus Tipo 2/fisiopatologia , Modelos Animais de Doenças , Regulação da Expressão Gênica , Marcação de Genes , Fator 1 Nuclear de Hepatócito , Fator 1-alfa Nuclear de Hepatócito , Fator 1-beta Nuclear de Hepatócito , Humanos , Fígado/patologia , Camundongos , Camundongos Mutantes , Fenótipo , Fatores de Transcrição/fisiologiaRESUMO
Disruption of the peroxisome proliferator-activated receptor gamma (PPAR gamma) gene causes embryonic lethality due to placental dysfunction. To circumvent this, a PPAR gamma conditional gene knockout mouse was produced by using the Cre-loxP system. The targeted allele, containing loxP sites flanking exon 2 of the PPAR gamma gene, was crossed into a transgenic mouse line expressing Cre recombinase under the control of the alpha/beta interferon-inducible (MX) promoter. Induction of the MX promoter by pIpC resulted in nearly complete deletion of the targeted exon, a corresponding loss of full-length PPAR gamma mRNA transcript and protein, and marked reductions in basal and troglitazone-stimulated expression of the genes encoding lipoprotein lipase, CD36, LXR alpha, and ABCG1 in thioglycolate-elicited peritoneal macrophages. Reductions in the basal levels of apolipoprotein E (apoE) mRNA in macrophages and apoE protein in total plasma and high-density lipoprotein (HDL) were also observed in pIpC-treated PPAR gamma-MXCre(+) mice. Basal cholesterol efflux from cholesterol-loaded macrophages to HDL was significantly reduced after disruption of the PPAR gamma gene. Troglitazone selectively inhibited ABCA1 expression (while rosiglitazone, ciglitazone, and pioglitazone had little effect) and cholesterol efflux in both PPAR gamma-deficient and control macrophages, indicating that this drug can exert paradoxical effects on cholesterol homeostasis that are independent of PPAR gamma. Together, these data indicate that PPAR gamma plays a critical role in the regulation of cholesterol homeostasis by controlling the expression of a network of genes that mediate cholesterol efflux from cells and its transport in plasma.
Assuntos
Transportadores de Cassetes de Ligação de ATP/genética , Apolipoproteínas E/genética , Colesterol/metabolismo , Macrófagos/metabolismo , Receptores Citoplasmáticos e Nucleares/deficiência , Receptores Citoplasmáticos e Nucleares/genética , Fatores de Transcrição/deficiência , Fatores de Transcrição/genética , Transportador 1 de Cassete de Ligação de ATP , Membro 1 da Subfamília G de Transportadores de Cassetes de Ligação de ATP , Alelos , Animais , Transporte Biológico Ativo , Éxons , Feminino , Expressão Gênica/efeitos dos fármacos , Marcação de Genes , Integrases/genética , Lipase Lipoproteica/genética , Macrófagos/efeitos dos fármacos , Camundongos , Camundongos Knockout , Camundongos Transgênicos , Poli I-C/farmacologia , Gravidez , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Receptores Citoplasmáticos e Nucleares/metabolismo , Deleção de Sequência , Fatores de Transcrição/metabolismo , Proteínas Virais/genéticaRESUMO
Hormone-stimulated lipolysis is a rapid way to mobilize fat from its storage depot for use in peripheral tissues. By convention, activation of cytosolic lipases via the ß-adrenergic receptor (ADRB2)-cAMP signaling pathway is the only molecular mechanism considered to liberate fatty acids from triglycerides stored in lipid droplets (LDs) of cells. Herein, we provide evidence that, aside from the activation of cytosolic lipases, autophagy contributes to this hormone-stimulated lipolysis. The ADRB2-stimulated lipolysis was reduced after inhibition of early or late autophagy using either pharmacological inhibitors or shRNA-mediated autophagic gene knockdown. ADRB2 stimulation has caused a marked increase in the autophagy-targeted LDs for lysosomal degradation, which is dependent on the LD-associated RAB7 as evidenced by the use of both shRNA-mediated RAB7 knockdown and a dominant-negative RAB7 mutant. In addition, RAB7 is involved in unstimulated (basal) lipolysis, and mediates the enhanced basal lipolysis in PLIN1/perilipin 1 knockdown fat cells. In conclusion, our results showed a contribution of lipophagy to both basal and hormone-stimulated lipolysis and that RAB7 plays a pivotal role in the regulation of this autolysosome-mediated lipid degradation in fat cells.
Assuntos
Lipólise , Lisossomos/metabolismo , Receptores Adrenérgicos beta/metabolismo , Proteínas rab de Ligação ao GTP/metabolismo , Células 3T3-L1 , Adipócitos/citologia , Adipócitos/metabolismo , Adipócitos/ultraestrutura , Animais , Autofagia , Proteínas de Transporte/metabolismo , AMP Cíclico/metabolismo , Lisossomos/ultraestrutura , Camundongos , Perilipina-1 , Fosfoproteínas/metabolismo , Proteínas rab de Ligação ao GTP/antagonistas & inibidores , proteínas de unión al GTP Rab7RESUMO
Upon nutrient deprivation, cells are thought to suppress biosynthesis but activate catabolic pathways to provide alternative energy sources and nutrients. However, here we provide evidence that in adult male C. elegans, both biosynthesis and degradation activities, including ribosome biogenesis and turnover, are enhanced during early starvation and appear to depend on the availability of intestinal lipid stores. Upon depletion of the intestinal lipids, further food deprivation results in a significant reduction in metabolic activity in the starved male worms. Our data show that adult C. elegans exhibits a two-phase metabolic response to starvation stress: an initial phase with enhanced metabolic activity that rapidly exhausts the lipid stores, followed by a phase with low metabolic activity, which outlasts the life of fed control worms. DAF-2 insulin/IGF-1 receptor signaling to the RAS pathway is required for the starvation-induced ribosome biogenesis and rapid lipid depletion in the initial phase of starvation.
Assuntos
Proteínas de Caenorhabditis elegans/metabolismo , Caenorhabditis elegans/metabolismo , Fator de Crescimento Insulin-Like I/metabolismo , Insulina/metabolismo , Mucosa Intestinal/metabolismo , Receptor IGF Tipo 1/metabolismo , Receptor de Insulina/metabolismo , Transdução de Sinais , Animais , Caenorhabditis elegans/genética , Proteínas de Caenorhabditis elegans/genética , Privação de Alimentos , Fator de Crescimento Insulin-Like I/genética , Metabolismo dos Lipídeos/genética , Longevidade/genética , Masculino , Atividade Motora , Reação em Cadeia da Polimerase em Tempo Real , Receptor IGF Tipo 1/genética , Receptor de Insulina/genética , Ribossomos/metabolismo , Espectrometria de Massas por Ionização e Dessorção a Laser Assistida por MatrizRESUMO
Hepatocyte nuclear factor 1alpha (HNF-1alpha) is a homeodomain-containing transcription factor and is important in postnatal growth and development in mice. In the HNF-1alpha-deficient liver, the expressions of a large set of growth hormone (GH)-responsive genes were significantly downregulated. By analyzing various HNF-1alpha mutant mice, we disclosed a mechanism by which hepatic HNF-1alpha regulates the expression of GH-responsive genes that are crucial for growth and development. We found that HNF-1alpha is required for the normal expression of glucocorticoid receptor (GR) specifically in livers. In the liver, GR, together with STAT5, is known to mediate the GH action by transactivating the GH-responsive genes that function in body growth and development. We further demonstrated that HNF-1alpha modulated GR gene expression by directly transactivating the GR gene promoter via a cryptic regulatory element located 3 bp upstream of the translation start site in exon 2 of the GR gene locus.
Assuntos
Tamanho Corporal/genética , Regulação da Expressão Gênica no Desenvolvimento , Fator 1-alfa Nuclear de Hepatócito/metabolismo , Fígado/metabolismo , Receptores de Glucocorticoides/metabolismo , Envelhecimento/metabolismo , Animais , Imunoprecipitação da Cromatina , Éxons , Feminino , Genes Reporter , Crescimento e Desenvolvimento/genética , Fator 1-alfa Nuclear de Hepatócito/genética , Masculino , Camundongos , Camundongos Knockout , Camundongos Transgênicos , Regiões Promotoras Genéticas , Receptores de Glucocorticoides/genética , Sequências Reguladoras de Ácido Nucleico , Fator de Transcrição STAT5/metabolismo , Sítio de Iniciação de Transcrição , Transcrição Gênica , Ativação TranscricionalRESUMO
Adipogenesis of preadipocytes in culture has been frequently used to study the molecular basis and effect of drugs on fat cell conversion. However, after adipogenic induction, cells respond to the inducing agent with various speeds of conversion and fat accumulation, which complicates direct molecular and biochemical analyses. Here we present a simple and sensitive method to detect and quantify fat accumulation inside cells by flow cytometry. Using this method, we detected elevated levels of cytoplasmic granularity that correlated well with an increased level of fat accumulated inside cells after adipogenic conversion. We further demonstrated the ability of this method to monitor and quantify fat cell maturation within a complex population of cells and to identify and collect the fat cells with similar fat storage for further analysis. Flow cytometry offers distinct advantages over existing detection systems for cytoplasmic lipid staining and lipid extraction and could represent a powerful analytical tool to monitor the effect of chemicals and biological molecules on fat cell conversion and maturation. Moreover, in combination with a cell sorting facility, our method offers a simple and efficient means of collecting fat cells of specific status for further analysis.
Assuntos
Adipócitos/metabolismo , Citometria de Fluxo/métodos , Metabolismo dos Lipídeos , Adipócitos/citologia , Animais , Linhagem Celular , Citometria de Fluxo/instrumentação , Lipídeos/análise , CamundongosRESUMO
CCAAT/enhancer-binding proteins, C/EBPalpha and C/EBPbeta, are required for fat cell differentiation and maturation. Previous studies showed that replacement of C/EBPalpha with C/EBPbeta, generating the beta/beta alleles in the mouse genome, prevents lipid accumulation in white adipose tissue (WAT). In this study, beta/beta mice lived longer and had higher energy expenditure than their control littermates due to increased WAT energy oxidation. The WAT of beta/beta mice was enriched with metabolically active, thermogenic mitochondria known for energy burning. The beta/beta allele exerted its effect through the elevated expression of the G protein alpha stimulatory subunit (Galphas) in WAT. Galphas, when overexpressed in fat-laden 3T3-L1 cells, stimulated mitochondrial biogenesis similar to that seen in the WAT of beta/beta mice, and effectively diminished the stored lipid pool.
Assuntos
Proteína alfa Estimuladora de Ligação a CCAAT/genética , Proteína beta Intensificadora de Ligação a CCAAT/genética , Proteínas de Ligação ao GTP/metabolismo , Mitocôndrias/metabolismo , Alelos , Animais , Metabolismo Energético , CamundongosRESUMO
Haploinsufficiency of the transcription factor gene Sim1 has been previously implicated in hyperphagic obesity in humans and mice. To investigate the relation between Sim1 dosage and hyperphagia, we generated sim1-knockout mice and studied their growth and feeding behavior. Heterozygous mice weaned on standard chow consumed 14% more food per day than controls and developed obesity, hyperinsulinemia, and hyperleptinemia. The sim1 heterozygous mice were also significantly longer than controls. Heterozygous animals had modestly increased feeding efficiency, suggesting reduced energy expenditure, but voluntary wheel-running activity did not differ significantly between the two groups. We studied the effect of dietary fat on the feeding behavior of heterozygous sim1 mutant mice. The tempo and severity of weight gain were much greater in animals weaned on a high-fat diet. When acutely challenged with increased dietary fat, sim1 heterozygous mice weaned on the chow diet markedly increased their food consumption and caloric intake, whereas control mice reduced the mass of food they consumed and maintained approximately isocaloric intake. In wild-type adult mice, we detected Sim1 expression in the paraventricular and supraoptic nuclei, as previously reported in neonates, as well as in the amygdala and lateral hypothalamus, all regions implicated in feeding behavior. Our results indicate that Sim1 gene dosage modulates the homeostatic feeding response to increased dietary fat and likely plays a physiological role in the regulation of energy balance.
Assuntos
Gorduras na Dieta/metabolismo , Comportamento Alimentar/fisiologia , Homeostase/fisiologia , Proteínas Repressoras/genética , Proteínas Repressoras/metabolismo , Envelhecimento/fisiologia , Animais , Fatores de Transcrição Hélice-Alça-Hélice Básicos , Constituição Corporal/fisiologia , Peso Corporal/fisiologia , Gorduras na Dieta/administração & dosagem , Feminino , Dosagem de Genes , Regulação da Expressão Gênica/fisiologia , Hiperfagia/fisiopatologia , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Fatores SexuaisRESUMO
Mice that lack IL-15 or the IL-15R alpha-chain (IL-15Ralpha) are deficient in peripheral CD8(+), but not in CD4(+), T cells. This CD8(+) T cell-specific deficiency has now been investigated further by characterization of a new strain of IL-15Ralpha(-/-) mice. The adult mutant mice exhibited a specific reduction in the percentage of CD8-single positive TCR(high) thymocytes. The expression of Bcl-2 was reduced in both CD8(+) thymocytes and naive T cells of the mutant animals, and the susceptibility of these cells to death was increased. Memory CD8(+) cells were profoundly deficient in IL-15Ralpha(-/-)mice, and the residual memory-like CD8(+) cells contained a high percentage of dead cells and failed to up-regulate Bcl-2 expression compared with naive CD8(+) cells. Moreover, exogenous IL-15 both up-regulated the level of Bcl-2 in and reduced the death rate of wild-type and mutant CD8(+) T cells activated in vitro. These results indicate that IL-15 and IL-15Ralpha regulate the expression of Bcl-2 in CD8(+) T cells at all developmental stages. The reduced Bcl-2 content in CD8(+) cells might result in survival defect and contribute to the reduction of CD8(+) cells in IL-15Ralpha(-/-)mice.
Assuntos
Linfócitos T CD8-Positivos/imunologia , Linfócitos T CD8-Positivos/metabolismo , Interleucina-15/genética , Proteínas Proto-Oncogênicas c-bcl-2/biossíntese , Receptores de Interleucina-2/deficiência , Receptores de Interleucina-2/genética , Animais , Linfócitos T CD8-Positivos/patologia , Morte Celular/genética , Morte Celular/imunologia , Diferenciação Celular/genética , Diferenciação Celular/imunologia , Cruzamentos Genéticos , Feminino , Interleucina-15/farmacologia , Subpopulações de Linfócitos/imunologia , Subpopulações de Linfócitos/patologia , Linfopenia/genética , Linfopenia/imunologia , Linfopenia/patologia , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Camundongos Transgênicos , Proteínas Proto-Oncogênicas c-bcl-2/antagonistas & inibidores , Receptores de Interleucina-15 , Timo/imunologia , Timo/patologia , Regulação para Cima/genética , Regulação para Cima/imunologiaRESUMO
CCAAT/enhancer-binding proteins (C/EBPs) are critical transcriptional regulators of differentiation of hematopoietic cells. Previous studies have shown that targeted disruption of the C/ebpalpha gene results in a lack of granulocytic differentiation with an arrest at the stage of immature myeloblasts. By using a gene replacement strategy in which C/EBPbeta was expressed from the C/ebpalpha gene locus of C/EBPalpha-null mice, we have evaluated the ability of C/EBPbeta to function for C/EBPalpha in directing differentiation along the granulocytic pathway. We show that the morphology and the differential cell counts of the bone marrow and peripheral blood cells from C/EBPbeta knockin mice are indistinguishable from those of their wild-type littermates, indicating that hematopoiesis occurs normally in these animals. Additionally, we analyzed expression of 21 myeloid-specific genes, including markers for distinct stages of granulocytic differentiation, and found no significant differences in their levels of expression in the bone marrow of C/EBPbeta knockin and wild-type mice. These results imply that C/EBPbeta can substitute for C/EBPalpha during hematopoiesis when expressed from the C/ebpalpha gene locus.