cAMP-responsive Element Modulator Expression Research Articles

A liver immune rheostat regulates CD8 T cell immunity in chronic HBV infection

Chronic hepatitis B virus (HBV) infection affects 300 million patients worldwide1,2, in whom virus-specific CD8 T cells by still ill-defined mechanisms lose their function and cannot eliminate HBV-infected hepatocytes3–7. Here we demonstrate that a liver immune rheostat renders virus-specific CD8 T cells refractory to activation and leads to their loss of effector functions. In preclinical models of persistent infection with hepatotropic viruses such as HBV, dysfunctional virus-specific CXCR6+ CD8 T cells accumulated in the liver and, as a characteristic hallmark, showed enhanced transcriptional activity of cAMP-responsive element modulator (CREM) distinct from T cell exhaustion. In patients with chronic hepatitis B, circulating and intrahepatic HBV-specific CXCR6+ CD8 T cells with enhanced CREM expression and transcriptional activity were detected at a frequency of 12–22% of HBV-specific CD8 T cells. Knocking out the inhibitory CREM/ICER isoform in T cells, however, failed to rescue T cell immunity. This indicates that CREM activity was a consequence, rather than the cause, of loss in T cell function, further supported by the observation of enhanced phosphorylation of protein kinase A (PKA) which is upstream of CREM. Indeed, we found that enhanced cAMP–PKA-signalling from increased T cell adenylyl cyclase activity augmented CREM activity and curbed T cell activation and effector function in persistent hepatic infection. Mechanistically, CD8 T cells recognizing their antigen on hepatocytes established close and extensive contact with liver sinusoidal endothelial cells, thereby enhancing adenylyl cyclase–cAMP–PKA signalling in T cells. In these hepatic CD8 T cells, which recognize their antigen on hepatocytes, phosphorylation of key signalling kinases of the T cell receptor signalling pathway was impaired, which rendered them refractory to activation. Thus, close contact with liver sinusoidal endothelial cells curbs the activation and effector function of HBV-specific CD8 T cells that target hepatocytes expressing viral antigens by means of the adenylyl cyclase–cAMP–PKA axis in an immune rheostat-like fashion.

Identification of the promoter region regulating the transcription of the REV7 gene

REV7 is involved in various biological processes including DNA repair and mutagenesis, cell cycle regulation, gene transcription, and carcinogenesis. REV7 is highly expressed in adult testicular germ cells as well as several malignant tumors. REV7 expression levels are associated with prognosis in several human cancers, however, the mechanism of REV7 transcriptional regulation has not been elucidated. In this study, we characterized the promoter region of the REV7 gene. A luciferase reporter assay using the human germ cell tumor cell line NEC8 was utilized to examine the upstream genomic region of REV7 for transcriptional activity, and two transcriptional activation regions were identified. We determined a small genomic region important for transcriptional activation using site-directed mutagenesis; this region is shared by several putative binding motifs for transcription factors, including the cAMP-responsive element modulator (CREM), cAMP-response element binding protein (CREB), and B-lymphocyte-induced maturation protein-1 (BLIMP-1). Exogenous CREM and CREB expression had no effect on the transcriptional activity in NEC8 cells or the human embryonic kidney cell line HEK293T. In contrast, exogenous BLIMP-1 expression increased luciferase reporter activity in HEK293T cells but unexpectedly decreased activity in NEC8 cells. Chromatin immunoprecipitation analysis demonstrated that BLIMP-1 binds to the genomic region near the binding motif in the REV7 promoter. Additionally, BLIMP-1 overexpression promoted endogenous REV7 expression in HEK293T cells. These findings suggest that BLIMP-1 may be a putative transcriptional regulator of REV7 in mammalian cells.

Proton-Pump Inhibitors Suppress T Cell Response by Shifting Intracellular Zinc Distribution.

Proton-pump inhibitors (PPI), e.g., omeprazole or pantoprazole, are the most widely used drugs for various gastrointestinal diseases. However, more and more side effects, especially an increased risk of infections, have been reported in recent years. The underlying mechanism has still not yet been fully uncovered. Hence, in this study, we analyzed the T cell response after treatment with pantoprazole in vitro. Pantoprazole preincubation reduced the production and secretion of interferon (IFN)-γ and interleukin (IL)-2 after the T cells were activated with phytohemagglutinin (PHA)-L or toxic shock syndrome toxin-1 (TSST-1). Moreover, a lower zinc concentration in the cytoplasm and a higher concentration in the lysosomes were observed in the pantoprazole-treated group compared to the untreated group. We also tested the expression of the zinc transporter Zrt- and Irt-like protein (Zip)8, which is located in the lysosomal membrane and plays a key role in regulating intracellular zinc distribution after T cell activation. Pantoprazole reduced the expression of Zip8. Furthermore, we measured the expression of cAMP-responsive element modulator (CREM) α, which directly suppresses the expression of IL-2, and the expression of the phosphorylated cAMP response element-binding protein (pCREB), which can promote the expression of IFN-γ. The expression of CREMα was dramatically increased, and different isoforms appeared, whereas the expression of pCREB was downregulated after the T cells were treated with pantoprazole. In conclusion, pantoprazole downregulates IFN-γ and IL-2 expression by regulating the expression of Zip8 and pCREB or CREMα, respectively.

Dynamic Expression and Chromatin Incorporation of ACT and CREM Transcription Factors in Testis Tissues of Infertile Men.

ObjectiveActivator of CREM in the testis (ACT) is a tissue specific transcription factor which activates cAMP responsive element modulator (CREM), a key transcription factor in differentiation of round spermatids into mature spermatozoa. They bind to CRE region in the promoters of transition protein genes (TNP1, TNP2) and protamine genes (PRM1 and PRM2), which are essential for sperm chromatin compaction, and regulates their transcription. This study was conducted to consider the expression of ACT and CREM and their regulatory roles on the expression of PRM1, PRM2, TNP1 and TNP2 genes in testis tissues of infertile men.Materials and MethodsIn this case-control study, testicular biopsies were collected from 40 infertile men and classified into three groups: obstructive azoospermia (OA, n=10, positive control), round spermatid maturation arrest (SMA, n=20), Sertoli cell-only syndrome (SCOS, n=10, negative control group). Using quantitative real-time polymerase chain reaction (PCR), the expression profile of ACT, CREM, TNP1, TNP2, PRM1 and PRM2 genes were assessed in testicular samples and incorporation of ACT and CREM proteins on the promoters of PRM1, PRM2, TNP1 and TNP2 genes were also evaluated by ChIP-real time PCR. ResultsOur results demonstrated significant decrease in the expression levels of ACT, CREM and in their incorporations on their target genes in SMA group in comparison to control groups (P<0.05).ConclusionThese data confirm that there is low expression and incorporation of ACT and CREM and of their target genes in infertilities which are associated with post-meiotic arrest.

Genome-Wide Association Study Reveals Genetic Link between Diarrhea-Associated Entamoeba histolytica Infection and Inflammatory Bowel Disease.

Entamoeba histolytica is the etiologic agent of amebic dysentery, though clinical manifestation of infection is highly variable ranging from subclinical colonization to invasive disease. We hypothesize that host genetics contribute to the variable outcomes of E. histolytica infection; thus, we conducted a genome-wide association study (GWAS) in two independent birth cohorts of Bangladeshi infants monitored for susceptibility to E. histolytica disease in the first year of life. Children with at least one diarrheal episode positive for E. histolytica (cases) were compared to children with no detectable E. histolytica infection in the same time frame (controls). Meta-analyses under a fixed-effect inverse variance weighting model identified multiple variants in a region of chromosome 10 containing loci associated with symptomatic E. histolytica infection. An intergenic insertion between CREM and CCNY (rs58000832) achieved genome-wide significance (P value from meta-analysis [Pmeta] = 6.05 × 10-9), and each additional risk allele of rs58000832 conferred 2.42 increased odds of a diarrhea-associated E. histolytica infection. The most strongly associated single nucleotide polymorphism (SNP) within a gene was in an intron of CREM (rs58468612; Pmeta = 8.94 × 10-8), which has been implicated as a susceptibility locus for inflammatory bowel disease (IBD). Gene expression resources suggest associated loci are related to the lower expression of CREM Increased CREM expression is also observed in early E. histolytica infection. Further, CREM-/- mice were more susceptible to E. histolytica amebic colitis. These genetic associations reinforce the pathological similarities observed in gut inflammation between E. histolytica infection and IBD.IMPORTANCE Diarrhea is the second leading cause of death for children globally, causing 760,000 deaths each year in children less than 5 years old. Amebic dysentery contributes significantly to this burden, especially in developing countries. The identification of host factors that control or enable enteric pathogens has the potential to transform our understanding of disease predisposition, outcomes, and treatments. Our discovery of the transcriptional regulator cAMP-responsive element modulator (CREM) as a genetic modifier of susceptibility to amebic disease has implications for understanding the pathogenesis of other diarrheal infections. Further, emerging evidence for CREM in IBD susceptibility suggests that CREM is a critical regulator of enteric inflammation and may have broad therapeutic potential as a drug target across intestinal inflammatory diseases.

6. Administration of Centella Leaf Extract (Centella asiatica (L.) Urban) for Decreasing cAMP Responsive Element Modulator (CREM) Expression in Testicular Seminiferous Tubule of Male Rats (Rattus norvegicus)

The objective of this study was to determine the effect of centella leaf extract administration on decreased of the molecule cAMP responsive element modulator (CREM) expression in the testicular seminiferous tubules of male rats (Rattus norvegicus). Eight rats, aged 3.5 months with 150-250 grams of body weight (BW) were used in this study. All rats were divided randomly into four groups as if K0 as a control group whereas K1, K2, and K3 were given the centella leaf extract with doses 125, 250, and 500 mg / kg body weight respectivelly that given once daily for 30 days. At the end of the treatment, rats were sacrificed and their testes were collected and subsequently fixed in buffered neutral formalin (BNF) 10% as fixative solution for histological preparation. The CREMs expressions were detected using immunohistochemical methods. The results showed that the number of CREM expression in the seminiferous tubules significantly differ (P 0.05) between K0 and the treatment group (K1, K2, and K3). Conclusion, the administration of centella leaf extract with of the dose 125, 250, and 500 mg/kg BW can decreased CREM expression spermatids of testicular seminiferous tubules in male rat.

Sulfur dioxide inhalation lowers sperm quality and alters testicular histology via increasing expression of CREM and ACT proteins in rat testes.

Sulfur dioxide (SO2) is one of the main atmospheric pollutants worldwide, and is reported to be responsible for the formation of severe haze in China. Some studies have demonstrated a potential harmful effect of SO2 on the male reproductive system; however the underlying mechanism is still unknown. The purpose of this study is to investigate the roles of cytochrome P450 (P450), cAMP-responsive element modulator (CREM), and activator of CREM (ACT) in SO2-induced toxicity. Forty-eight male Wistar rats were randomly divided into an experimental and control group. The experiment group was exposed to SO2 in ambient air (10ppm, 4h/day), and the control group was treated with filtered air in the same conditions. After 2 weeks, the results showed a significant decrease in body weight and sperm motility, and an increase in the testis weight-to-body weight ratio as compared to the control group. Histological investigation suggested that SO2 exposure led to loose arrangement of the spermatogenic cells and local structural damage in the seminiferous tubules. Moreover, the expressions of P450, CREM and ACT proteins increased in the testes by 0.22%, 47.26% and 23.38%, respectively. Taken together, SO2 inhalation lowered sperm quality, altered testicular histology, and increased expressions of CREM and ACT proteins in the testes of rats. Overall, these results could contribute to a better understanding of SO2-induced male reproductive toxicity.

Effects of Fluoride on Expression of P450, CREM and ACT Proteins in Rat Testes.

Fluoride (F) is an essential trace element that humans and animals ingest from water, air, and fluoride-containing products; however, excessive fluoride absorption can damage a variety of organs and tissues, including the male reproductive system. Our previous studies found that fluoride exposure lowered sperm quality and interfered with spermatogenesis; however, the exact mechanism remained unclear. Proteins cytochrome P450 (P450), cAMP-responsive element modulator (CREM), and activator of CREM in testis (ACT) play the key roles in spermatogenesis and sperm motility. To investigate whether fluoride affects the expression of P450, CREM, and ACT, we used immunohistochemical techniques to determine expression levels of these proteins in testes of rats administered 100mg NaF/L for 2weeks via drinking water. The results showed that P450 expression was decreased while CREM and ACT expression was increased in the fluoride group, compared to the control. These data suggest that fluoride can impair male reproduction by affecting expression of P450, CREM, and ACT in the testes.

EXPRESSION PROFILING OF CREM GENE IN TESTIS WITH NORMAL AND IMPAIRED SPERMATOGENESIS IN EGYPTIAN MALES

cAMP responsive element modulator (CREM) is one of the most important transcription factors expressed in male testes which connect the extra cellular signals to gene regulation. CREM expression switches from a repressor to an activator in testes during spermatogenesis. Any alteration in this switch leads to different testicular patterns. Methods: Total RNA was extracted from Eighty eight testicular biopsy and analyzed for CREM expression profiling. Normal spermatogenesis showed expression of CREM2and gamma repressor, the same finding was detected in Hypospermatogenesis group but with another longer repressor belong to alpha repressor type, 95% of Round spermatid maturation arrest group showed two repressor patterns, and 5% showed two activator transcripts of CREM2 activator. Sertoli cells only group didn’t show any activator transcripts of CREM. In conclusion studying the mechanisms of interaction between CREM repressors and activators in the normal and impaired spermatogenesis may lead to better understanding of genetic control of the spermatogenesis and consequently to better treatment options.

Astragalus membranaceus Ameliorates Reproductive Toxicity Induced by Cyclophosphamide in Male Mice

The root of Astragalus membranaceus B(UNGE) (AM) is a medicinal herb that has been capable of reducing the adverse effects of conventional chemotherapy. To investigate the effects of AM on cyclophosphamide (CP)-induced reproductive toxicity in mouse testes, 5-week-old male imprinting control region mice were divided into five groups; CP was treated on the first day of each week for 5 weeks (100 mg/kg, i.p.), and AM was treated for 5 days a week for 5 weeks. At the end of the treatment period, the testes were taken out, cleared of the adhering tissues, and weighed. Epididymis was taken out and used for sperm analysis. Testis samples were frozen for real-time quantitative PCR and Western blot analysis. AM treatment increased diminished relative testes weight, and sperm count and motility in mice treated with CP. CP treatment has detrimental effects on the expression of cAMP-responsive element modulator (CREM), a transcription factor that is highly expressed in male germ cells and is crucial to post-meiotic germ cell differentiation. AM restored CREM at both the mRNA and protein levels. AM has beneficial influences and appears able to ameliorate relative testes weight, sperm parameters, and CREM expression against CP-induced reproductive toxicity.

Transcriptional Activation of the cAMP-responsive Modulator Promoter in Human T Cells Is Regulated by Protein Phosphatase 2A-mediated Dephosphorylation of SP-1 and Reflects Disease Activity in Patients with Systemic Lupus Erythematosus

Systemic lupus erythematosus (SLE) is a complex autoimmune disease with numerous abnormalities recorded at the cellular, molecular, and genetic level. Expression of the basic leucine zipper transcription factor cAMP-responsive element modulator (CREM)α was reported to be abnormally increased in T cells from SLE patients. CREMα suppresses IL-2 and T cell receptor ζ chain gene transcription by direct binding to the respective promoters. Here, we show that increased CREM expression is the result of enhanced promoter activity. DNA binding analyses reveal direct binding of transcription factor specificity protein-1 (SP-1) to the CREM promoter resulting in enhanced transcriptional activity and increased CREM expression. Protein phosphatase 2A is known to activate SP-1 through dephosphorylation at its serine residue 59. Our results show that nuclei from SLE T cells contain lower levels of Ser(59)-phosphorylated SP-1 protein and a stronger SP-1 binding to the CREM promoter. We conclude that protein phosphatase 2A accounts for enhanced SP-1 dephosphorylation at Ser(59) in SLE T cells. More importantly, CREM promoter activity mirrors reliably disease activity in SLE patients, underscoring its potential role as a biomarker for the prediction of flares in SLE patients.

Evaluation of the effects of Salvia hypoleuca on the cAMP-responsive element modulator (CREM) gene expression and spermatogenesis in rat

Objective Salvia species which are medicinal herbs have been used to improve male reproductive functions in traditional medicine. They also, have been used to treat several diseases. In this present study, effects of Salvia hypoleuca on male rat reproductive function were investigated by sperm analysis and assessment of CREM expression at mRNA and protein levels.

Effects of Rubus coreanus on sperm parameters and cAMP-responsive element modulator (CREM) expression in rat testes

Rubi Fructus (RF), the dried, unripe fruit of Rubus coreanus M IQ. (Rosaceae), has been used to improve male reproductive function in traditional Korean medicine. In this study, we investigated the effects of RF on sperm parameters and expression of cAMP-responsive element modulator (CREM), which has a crucial role in spermatogenesis. RF was administered to 8-week-old male Wistar rats for 56 consecutive days (1.0 g/kg, daily, p.o.). Sperm analysis, RT-PCR, and Western blot assays were then carried out. The RF-treated animals showed significant increases in the weight of the testes, epididymal sperm count, and sperm motility compared to the control group. RF also increased the expression of CREM at both the mRNA and protein levels. These results suggest that RF may improve male fertility by enhancing spermatogenesis.

Yukmijihwang-tang protects against cyclophosphamide-induced reproductive toxicity

A side effect of cyclophosphamide (CP), an alkylating agent widely used to treat tumors and autoimmune disorders, is the alteration of male reproductive function. Yukmijihwang-tang (YJT) is a multi-herbal medicinal formula that has been used in traditional Asian medicine to treat male reproductive problems. In this study, we investigated the effects of YJT on CP-induced reproductive toxicities in rat testes. Eight-week-old male Wistar rats were divided into three groups: vehicle-treated (control), CP-treated and CP + YJT-treated groups. CP was administered for the first 7 days (20 mg/kg/day, p.o.), and YJT was administered for 56 days consecutively (1.0 g/kg/day, p.o.). The CP-treated group showed significant decreases in the weight of the testes, epididymal sperm count and sperm motility compared to the control group, while the CP + YJT-treated group had significant increases for these variables compared to the CP-treated group. The enhancement of lipid peroxidation by CP in the rat testes was reduced by YJT treatment. CP diminished the expression of cAMP-responsive element modulator (CREM), a transcription factor that is highly expressed in male germ cells and is crucial to post-meiotic germ cell differentiation. YJT restored CREM at both the mRNA and protein levels. These results suggest that YJT has a protective effect against CP-induced reproductive toxicities by inhibiting the increases in lipid peroxidation and enhancing CREM expression.

Crem Activator Isoforms in Normal and Impaired Human Spermatogenesis Analyzed by Real Time RT-PCR

cAMP responsive element modulator (CREM) activator isoforms are involved in mammalian spermatogenesis and spermiogenesis. CREM proteins are highly expressed in postmeiotic germ cells of rodents and primates. Homozygous CREM inactivated mice exhibit round spermatid maturation arrest. The lack of CREM expression at both the mRNA and protein levels is associated with spermatid maturation arrest in infertile patients. Using real-time RT-PCR, we have examined the levels of CREM activator isoform mRNAs: CREMtheta1, CREMtheta2 and CREMt2 + Ex-gamma in gametogenic and interstitial cell fractions from normal human testis, in homogenized tissue samples from spermatogenic arrest and from testicular tumors. We have shown for the first time the presence of CREM activator isoform containing exon gamma (CREMtau2 + Exgamma) in normal human spermatogenesis. Among the three CREM isoforms, CREMtheta1 was expressed in its highest level in the male gonads. In comparison, CREMtheta2 mRNA was significantly less suggesting that the P3 promoter is much more active in human testis than the P4 promoter. Minimal-nill levels of mRNA for either of the CREM activator isoforms were detected in lymphocytes or in gonadal tissues from patients with SCOS (Sertoli Cell Only Syndrome). This data underlines the significance of CREMtheta1 isoform in the regulation of transcription during post-meiotic germ cell differentiation.

Expression of cAMP‐responsive element modulator (CREM) and reproductive functions of Corni fructus in rat testes

Corni fructus (CO), the fruit of Cornus officinalis Sieb. et Zucc., is known by the common name of Asiatic cornelian cherry and dogwood fruit and it has been considered to possess tonic actions and enhance the motility of human sperm. In this study, we investigated the effects of CO on sperm analysis, serum testosterone, lipid peroxidation and the expression of CREM in rat testes. After 56 days treatment of CO, the epididymal sperm counts significantly increased of 46.92% than those in the vehicle treated group (p < 0.01). The sperm motility also significantly improved of 24.07% by the treatment of CO (p < 0.05). Serum testosterone levels in control and CO-treated groups were 3.65 +− 1.14 nmol/L and 5.35 +− 1.27 nmol/L, respectively. CO treatment significantly reduced the lipid peroxide (LPO) production of 54.67% in the rat testes. The relative expression of CREM mRNA in the CO treated group was 153.11% than that in the control group (p < 0.05). Western blotting analysis confirmed this data. In conclusion, CO has improved the sperm parameters, LPO production, the serum testosterone level. Moreover, CREM expressions were stimulated by CO in the RNA and protein levels. From these results, CO has the enhancing effects on reproductive functions through multiple pathways.

The Administration of Retinoic Acid Down-Regulates cAMP-Responsive Element Modulator (CREM) mRNA in Vitamin A-Deficient Testes

Studies using genetics and vitamin A deficiency (VAD) have shown that vitamin A and retinoids play essential roles in spermatogenesis at the pre-meiotic stage. To understand the mechanisms of control in spermatogenesis by retinoic acid, we investigated whether retinoic acids regulate the expression of downstream transcription factors that are essential for spermatogenesis. In this study, we found that administration of all-trans retinoic acid (ATRA) or retinol to VAD rats down-regulates the testicular mRNA levels of the cAMP responsive element modulator (CREM), an essential transcription factor for spermatogenesis. Conversely, depletion of retinoids from the diet leds to an up-regulation of CREM expression in adult testes. In addition, RT-PCR analysis indicated that ATRA specifically represses the expression of the activator spliced variant of CREM (CREMtau). These results suggest that retinoids function as a negative regulator of CREM expression in testes.

Expression of activator of CREM in the testis (ACT) during normal and impaired spermatogenesis: correlation with CREM expression.

The cAMP-responsive element modulator (CREM) is involved in regulating gene expression in haploid spermatids. Transcriptional activity of the CREM protein is thought to be regulated by activator of CREM in the testis (ACT). Applying RT-PCR and in situ hybridization, cell-specific gene expression of ACT was demonstrated in man, cynomolgus monkey and mouse. During normal spermatogenesis, RT-PCR revealed a strong signal in all three species. We sequenced monkey ACT cDNA and demonstrated that the putative amino acid sequence is highly conserved between these species. In situ hybridization demonstrated ACT mRNA in mid and late pachytene spermatocytes and in round spermatids. Among four infertile men with round spermatid maturation arrest (RSMA), only one patient revealed a strong signal for ACT, while three patients displayed a weak signal for both RT-PCR and in situ hybridization, although germ cells normally expressing ACT were present in these patients. In addition, CREM knockout mice known to be infertile due to RSMA also exhibited only a weak amplification product for ACT cDNA. ACT mRNA was barely detectable in some round spermatids, but was completely absent in pachytene spermatocytes. Database search revealed two and one CRE within the putative human and mouse ACT promoters respectively. Our findings indicate a conserved function of ACT during the evolution of mammalian spermatogenesis and suggest a role for CREM in ACT transcriptional regulation.

Different CREM-isoform gene expression between equine and human normal and impaired spermatogenesis

Histone-to-protamine exchange causes chromatin condensation ceasing gene expression in elongating spermatids. Gene expression of protamines is regulated by the transcription factor cAMP-responsive element modulator (CREM). Altered CREM expression results in male infertility, as shown by CREM-knock-out mice being sterile due to round spermatid maturation arrest and patients exhibiting round spermatid maturation arrest revealing a lack or substantial reduction of both CREM-mRNA and CREM-protein. Similar defects in histone-to-protamine exchange have been suggested in infertile stallions exhibiting enlarged sperm heads. The CREM-gene consists of 14 exons. Alternative exon splicing results in the production of both activator and repressor proteins. To further clarify the role of different CREM-isoforms for male infertility, the expression pattern of various CREM-isoforms during equine and human normal and impaired spermatogenesis was investigated by RT-PCR. Stallions with normal spermatogenesis expressed six activators and three repressors. In men three activators and seven different repressors were detected. In one stallion and patients with impaired spermatogenesis, only repressors were found. It is concluded that (i) stallion and man reveal a different CREM expression pattern, (ii) the expression of CREM activators is a prerequisite for normal spermatogenesis, and (iii) the lack of CREM activator expression results in male infertility.

Expression of cAMP-responsive element modulator (CREM) in rat testes following chronic cocaine administration.

c-AMP-responsive element modulator (CREM), one of the nuclear factors involved in the regulation of gene expression by cAMP, has an important role in spermatogenesis. Our recent study has shown that chronic administration of cocaine to male rats results in disruption of spermatogenesis, including reduction of germ cells. As a further step toward understanding this process, we have studied the role of CREM in cocaine-induced testicular damage. Sprague-Dawley rats were administered cocaine hydrochloride subcutaneously daily for 90 days. Control animals received equal volumes of normal saline daily for 90 days. Testes were removed after 15, 30, 90 days of cocaine administration. Total RNA was extracted from the testes and subjected to RT-PCR. Testicular tissue was also homogenized in a lysis buffer, and Western blotting was performed using anti-CREM antibody. RT-PCR analysis detected a single fragment of approximately 520 base pairs (bp) in control testes at all time points. The cocaine-treated testes showed reduced expression of CREM fragment. Western blot analysis using CREM antibodies confirmed the RNA data. There were reduced CREM proteins in the cocaine-treated testes compared with controls. The CREM gene is essential for spermatogenesis. Our results indicate that the reduction in testicular CREM expression may be one of the mechanisms responsible for disruption or impairment of spermatogenesis in the testes following chronic cocaine administration.