Chronic exposure to cannabinoids during adolescence causes long-lasting behavioral deficits in adult mice.

Regular use of marijuana during adolescence enhances the risk of long-lasting neurobiological changes in adulthood. The present study was aimed at assessing the effect of long-term administration of the synthetic cannabinoid WIN55212.2 during adolescence in young adult mice. Adolescent mice aged 5 weeks were subjected daily to the pharmacological action of WIN55212.2 for 3 weeks and were then left undisturbed in their home cage for a 5-week period and finally evaluated by behavioral testing. Mice that received the drug during adolescence showed memory impairment in the Morris water maze, as well as a dose-dependent memory impairment in fear conditioning. In addition, the administration of 3 mg/kg WIN55212.2 in adolescence increased adult hippocampal AEA levels and promoted DNA hypermethylation at the intragenic region of the intracellular signaling modulator Rgs7, which was accompanied by a lower rate of mRNA transcription of this gene, suggesting a potential causal relation. Although the concrete mechanisms underlying the behavioral observations remain to be elucidated, we demonstrate that long-term administration of 3 mg/kg of WIN during adolescence leads to increased endocannabinoid levels and altered Rgs7 expression in adulthood and establish a potential link to epigenetic changes.

Social defeat leads to changes in the endocannabinoid system: An overexpression of calreticulin and motor impairment in mice.

Prolonged and sustained stimulation of the hypothalamo-pituitary-adrenal axis have adverse effects on numerous brain regions, including the cerebellum. Motor coordination and motor learning are essential for animal and require the regulation of cerebellar neurons. The G-protein-coupled cannabinoid CB1 receptor coordinates synaptic transmission throughout the CNS and is of highest abundance in the cerebellum. Accordingly, the aim of this study was to investigate the long-lasting effects of chronic psychosocial stress on motor coordination and motor learning, CB1 receptor expression, endogenous cannabinoid ligands and gene expression in the cerebellum. After chronic psychosocial stress, motor coordination and motor learning were impaired as indicated the righting reflex and the rota-rod. The amount of the endocannabinoid 2-AG increased while CB1 mRNA and protein expression were downregulated after chronic stress. Transcriptome analysis revealed 319 genes differentially expressed by chronic psychosocial stress in the cerebellum; mainly involved in synaptic transmission, transmission of nerve impulse, and cell-cell signaling. Calreticulin was validated as a stress candidate gene. The present study provides evidence that chronic stress activates calreticulin and might be one of the pathological mechanisms underlying the motor coordination and motor learning dysfunctions seen in social defeat mice.

Alternative splicing of exon 3b gives rise to ODF2 and Cenexin.

ODF2 was first identified as the major component of the sperm tail outer dense fibers. Additionally, ODF2 is a critical component of the mature centriole of the animal centrosome where it locates to the distal appendages. Moreover, generation of primary cilia strictly depends on ODF2. The mature centriole is characterized further by recruitment of Cenexin. Albeit highly similar in sequence the relationship between ODF2 and Cenexin has not been investigated. We demonstrate here that ODF2 and Cenexin are alternative splice products by identifying a novel exon 3b encoding Cenexin specific amino acids. Even though ODF2 is the main isoform in testicular tissue RT-PCR analyses revealed that isoforms are not restricted to specific tissues.

Molecular aspects of XY body formation.

More than a century ago, a densely stained area inside the nucleus of male meiotic cells was described. It was later shown to harbor the sex chromosomes which undergo transcriptional inactivation in conjunction with heterochromatinisation and synapsis to form the XY body. Formation of the XY body is conserved throughout the mammalian phylogenetic tree and is thought to be essential for successful spermatogenesis. However, its biological role as well as the molecular mechanisms underlying XY body formation are still far from being understood. A lot of effort has already been undertaken to characterize components of the XY body and to investigate their functional implications in sex chromatin heterochromatinisation and meiotic sex chromosome inactivation (MSCI). This review gives an overview of those components and their possible implications in XY body formation and function.

Histone H1t is not replaced by H1.1 or H1.2 in pachytene spermatocytes or spermatids of H1t-deficient mice.

The linker histone gene H1t is exclusively expressed in the mammalian testis. In former experiments we have shown that H1.1 and H1.2 histone gene expression is significantly enhanced in testis of adult H1t deficient mice. In this report we have quantified the mRNA of different H1 genes in 9-day- and 20-day-old wild type and H1t knock out mice. In addition, we have analysed the distribution of H1.1 and H1.2 protein by immunofluorescent staining in spread male germ cells. The aim of this work was to answer the question whether H1t can be replaced during spermatogenesis by H1.1 or H1.2. In our experiments we could not detect elevated levels of H1.1 or H1.2 in pachytene spermatocytes or haploid cells of H1t deficient testis. Therefore, in these cells, H1t seems not to be replaced by H1.1 or H1.2.

Genomic organisation and chromosomal assignment of ODF2 (outer dense fiber 2), encoding the main component of sperm tail outer dense fibers and a centrosomal scaffold protein.

ODF2 (outer dense fiber 2) was first described as the main protein component of the sperm tail cytoskeleton, the outer dense fibers, but was shown recently to be a component of the centrosomal scaffold in chicken. In mouse two related ODF2 cDNA clones were isolated which have been suggested to be most likely the result of alternative splicing. We show here the exon/intron organisation of mouse ODF2 and demonstrate that alternative splicing results in related cDNA sequences and most likely explains, at least partially, the highly complex protein pattern detected on Western blots. ODF2 was mapped to rat chromosome 3 and more specifically by FISH analysis at bands 3q11-->3q12. In addition, we demonstrate that ODF2 is indeed a component of the centrosome and the mitotic spindle poles in mammals.

Histone macroH2A1.2 is concentrated in the XY-body by the early pachytene stage of spermatogenesis.

The pairing of sex chromosomes during meiosis in male mammals is associated with ongoing heterochromatinization and X inactivation. This process occurs in a specific area of the nucleus that can be discerned morphologically: the sex vesicle or XY-body. In contrast to X inactivation in the somatic cells of female mammals the reasons for X inactivation in the male germline remain obscure. We have recently demonstrated that the inactive X chromosome in somatic cells of female mammals is marked by a high concentration of histone macroH2A. Here we investigate X inactivation in the meiotic cells of the male germline. We demonstrate here that macroH2A1.2 is present in the nuclei of germ cells starting first with localization that is largely, if not exclusively, to the developing XY-body in early pachytene spermatocytes. Our results suggest that inactivation of sex chromosomes in the male germ cell includes a major alteration of the nucleosomal structure.

The murine heterochromatin protein M31 is associated with the chromocenter in round spermatids and Is a component of mature spermatozoa.

In mature sperm the normal nucleosomal packaging of DNA found in somatic and meiotic cells is transformed into a highly condensed form of chromatin which consists mostly of nucleoprotamines. Although sperm DNA is highly condensed it is nevertheless packaged into a highly defined nuclear architecture which may be organized by the heterochromatic chromocenter. One major component of heterochromatin is the heterochromatin protein 1 which is involved in epigenetic gene silencing. In order to investigate the possible involvement of heterochromatin protein in higher order organization of sperm DNA we studied the localization of the murine homologue of heterochromatin protein 1, M31, during chromatin reorganization in male germ cell differentiation. Each cell type in the testis showed a unique distribution pattern of M31. Colocalization to the heterochromatic regions were found in Sertoli cells, in midstage pachytene spermatocytes, and in round spermatids in which M31 localizes to the centromeric chromocenter. M31 cannot be detected in elongated spermatids or mature spermatozoa immunocytologically, but could be detected in mature spermatozoa by Western blotting. We suggest that M31, a nuclear protein involved in the organization of chromatin architecture, is involved in higher order organization of sperm DNA.

M31, a murine homolog of Drosophila HP1, is concentrated in the XY body during spermatogenesis.

The formation of the sex vesicle, or XY body, during male meiosis and pairing of the sex chromosomes are thought to be essential for successful spermatogenesis. Despite its cytological discovery a century ago, the mechanism of XY body formation, particularly heterochromatinization of the sex chromosomes, has remained unclear. The HP1 class of chromobox genes are thought to encode proteins involved in the packaging of chromosomal DNA into repressive heterochromatin domains, as seen, for example, in position-effect variegation. Study of the distribution of a murine HP1-like chromodomain protein, M31, during spermatogenesis revealed spreading from the tip of the XY body in mid-stage pachytene spermatocytes to include the whole of the XY body in late-pachytene spermatocytes. We also demonstrate that the formation of the XY body during spermatogenic progression in neonatal mice coincides with the expression of a novel nuclear isoform of M31, M31(p21). These results support the view that a common mechanistic basis exists for heterochromatin-induced repression, homeotic gene silencing, and sex-chromosome inactivation during mammalian spermatogenesis.

Outer dense fibre proteins from human sperm tail: molecular cloning and expression analyses of two cDNA transcripts encoding proteins of approximately 70 kDa.

The outer dense fibres (ODF) are a main cytoskeletal structure of the sperm tail. Despite their importance in the morphology and function of the sperm tail, their constituents are poorly described. Here we investigate the protein composition of human outer dense fibres. Our results suggest that human ODF consist of about 10 major and of at least 15 minor proteins, where all major proteins are ODF1, ODF2 or ODF2-related proteins. From a human testis cDNA library, we isolated two slightly different cDNAs encoding ODF2 proteins of approximately 70 kDa. Human ODF2 cDNAs and their encoded proteins are very similar to those isolated from rat and mouse pointing to a high evolutionary pressure residing on these proteins. Transcription of ODF2 is restricted to testis tissue and more specifically to round spermatids as was demonstrated by a non-radioactive in-situ hybridization. ODF2 proteins were detected in the sperm tail. Their distribution along the length of the sperm tail shows that the ODF normally extend to about half the principal piece of the sperm tail. The former result opens the possibility for a screening regarding the distribution of sperm tail proteins related to motility disorders.

Mouse Odf2 cDNAs consist of evolutionary conserved as well as highly variable sequences and encode outer dense fiber proteins of the sperm tail.

The outer dense fibers (ODF) of the mammalian sperm tail comprise a unique, specialized, and very prominent structure, consisting of nine fibers surrounding the axoneme. The ODF may play an important but as yet undefined role in sperm morphology, integrity and function. Study of the ODF is hampered by insufficient knowledge of their protein composition and the genetic regulation of their synthesis. We report here on the characterization of cDNAs encoding the Odf2 proteins of outer dense fibers of mouse sperm. We isolated two cDNA clones with variable 5' regions. Variability in sequence is restricted to specific regions in the N-terminal part of the encoded proteins, whereas the C-terminal part is highly conserved in Odf2 proteins both between species and within a species. This variability is confirmed at the protein level. The outer dense fibers could be detected immunologically in total sperm tails allowing a direct comparison of their length in relation to the length of the sperm tail. Odf2 transcripts could be demonstrated in testicular RNA and are restricted to germ cells. The start of transcription is in step 5 spermatids of tubular stage V and the RNA could be detected in the cytoplasm of differentiating spermatids in all subsequent tubular stages.

Identification and characterization of new cDNAs encoding outer dense fiber proteins of rat sperm.

A main structure of the mammalian sperm tail is a structure known as the outer dense fibers whose molecular composition as well as their function are still mostly unknown. We report here the isolation and characterization of new cDNAs (odf2) that identifies a highly variable gene locus encoding outer dense fiber proteins. Transcription of odf2 is restricted to testis and more specifically to round spermatids. Transcription starts in step 6 spermatids, which coincides with transcription of the major outer dense fiber protein gene odf1 (Burmester, S., and Hoyer-Fender, S. (1996) Mol. Reprod. Dev. 45, 10-20) and with the formation of the sperm tail. Affinity-purified anti-Odf2 antibodies identified isolated outer dense fibers immunocytochemically and detected at least three protein bands in the molecular mass range of 65,000 to 70,000 Da in total Odf protein preparations. Presence of several protein bands correlates with the presence of several transcripts and the isolation of slightly different cDNA clones, whereas Southern blot hybridization does not indicate the presence of multiple genes. Computer analyses of the structure of the encoded Odf2 protein revealed an overall alpha-helical structure with two regions identical to the dimerization region of the leucine zipper motif.

Transcription and translation of the outer dense fiber gene (Odf1) during spermiogenesis in the rat. A study by in situ analyses and polysome fractionation.

Transcription and translation of the Odf1 gene encoding the major protein of sperm tail outer dense fibers has been investigated in rat spermatogenesis. Odf1 mRNA was detected by in situ hybridization from step 6 round spermatids up to step 17. The protein was detected immunohistochemically in the cytoplasm of step 7 spermatids up to step 18 and in the sperm tails. The distribution of Odf1 mRNA and the respective transcript sizes in polysomes and translationally inactive nonpolysomal ribonucleoprotein particles has been investigated by fractionation on sucrose gradients and Northern blot analysis of the isolated RNA. In adult rat testis about 30% of Odf1 mRNA is associated with the polysomal fraction, but the bulk is stored in translationally inactive ribonucleoprotein particles. In 35-day old rat testis, in which spermatids have reached step 15 of spermiogenesis, only about 10% of Odf1 mRNA can be found in the polysomal fraction. It seems therefore, that translation of Odf1 is greatly enhanced in the maturation phase of spermiogenesis during which a marked increase in diameter of outer dense fibers takes place. In the polysomal fraction, Odf1 transcripts are of heterogeneous size. Northern blot analysis of fractionated RNA digested with RHaseH revealed the presence of both Odf1 transcripts (Burfeind and Hoyer-Fender, 1991: Dev Biol 148: 195-204; Burfeind et al., 1993: Eur J Biochem 216: 497-505) on polysomes. While the larger transcript population is heterogeneous in size due to variable polyA-shortening, the smaller transcript population is not deadenylated compared to those present in nonpolysomal fractions.

Sequence of mouse Odf1 cDNA and its chromosomal localization: extension of the linkage group between human chromosome 8 and mouse chromosome 15.

The mouse cDNA encoding the major protein of the outer dense fibers in sperm tails was isolated by reverse transcription of testicular RNA and amplification with sequence-specific primers. Sequencing of a genomic clone obtained by inverse PCR yielded the 5' untranslated region. The transcription starting point was verified by primer extension. The putative proteins encoded by Odf1 in mouse and by ODF1 in rat and man are very similar. A total of 15 amino acids in the C-terminal region were deleted in the mouse protein, compared with the rat protein. Through in situ hybridization to metaphase chromosomes, the Odf1 gene was localized to mouse chromosome 15 region B2-C. The chromosomal localization of the Odf1 gene extends the hitherto known linkage group consisting of MYC (Myc), PVT1 (Pvt1), GPT (Gpt), and TG (Tg) common to human chromosome 8 and mouse chromosome 15 in the proximal direction of both chromosomes. The linkage group now extends from band q24 to band q22 of human chromosome 8 and from region D2-E to region B2-C of mouse chromosome 15.

Expression and chromosomal mapping of the gene encoding the human histone H1.1.

The expression of a human histone H1 isoform (H1.1) was studied in several human tissues. Northern blot analysis has revealed that this gene is expressed in testis and thymus, but not in other human tissues. In this report, we demonstrate that the expression of the histone H1.1 gene in human testis is restricted to early round spermatids that belong to the fraction of postmeiotic sperm cells. Transcripts hybridizing with the human H1.1 gene could not be detected in testis of mouse, rat, bull or boar. Southern blot analysis with human genomic DNA, DNA from different Old World monkeys (chimpanzee, orangutan, gorilla and rhesus monkey) and DNA from several mammalian species has revealed that the histone H1.1 gene is highly conserved in higher primates, whereas no cross-hybridization can be detected with DNA from other mammalian species such as mouse, rat, hamster or bull. In a previous report, the human histone H1.1 gene and other H1 genes (H1.2-H1.5, H1t) were assigned to chromosome 6 by polymerase chain reaction analysis using human-rodent cell hybrid DNA; fluorescence in situ hybridization indicated that these genes form part of a major gene cluster on the short arm of chromosome 6. We have confirmed the localization of histone H1.1 to chromosome 6 and have regionally assigned the locus to 6p21.3 by radioactive in situ hybridization.

Sequence, expression, and chromosomal assignment of a human sperm outer dense fiber gene.

Outer dense fibers (ODFs) are located on the outside of the axoneme in the midpiece and principal piece of the mammalian sperm tail and may help to maintain the passive elastic structures and elastic recoil of the sperm tail. We have identified and describe here a human gene that is homologous to the Mst(3)CGP gene family of Drosophila melanogaster and encodes an ODF protein of 241 amino acids. The transcribed region has a size of approximately 1 kb and contains two exons of 416 bp and 406 bp, respectively, not including the 3' untranslated region. The gene is expressed in testis but not in human spleen, kidney, or brain and resembles in this respect the expression of the Drosophila Mst(3)CGP gene family in the male germline. An antiserum raised against a synthetic peptide derived from the N-terminus of the encoded sequence identified a protein of approximately 32 kDa in an extract of human sperm flagella. By Southern-blot analyses and in situ hybridization, the ODF gene was localized to band q22 of chromosome 8. The isolation of a human gene encoding a sperm tail protein may provide the ability to identify and investigate, on the molecular level, possible reasons for human male infertility that are dependent on flagellar disturbances.

Structure and chromosomal assignment of a gene encoding the major protein of rat sperm outer dense fibres.

Outer dense fibres are located on the outside of the axoneme in the midpiece and principal piece of the mammalian sperm tail and may help to maintain the passive elastic structures and elastic recoil of the sperm tail. Here we describe the isolation and genomic organization of a rat gene encoding a cysteine-proline-rich outer dense fibre protein. The cDNA sequence of rts 5/1 and its expression pattern have already been published [Burfeind, P. & Hoyer-Fender, S. (1991) Dev. Biol. 148, 195-204]. There exist two different genes in the rat genome, rts 5/1 major and rts 5/1 minor. Rts 5/1 major consists of two exons interrupted by one intron of about 3.8 kb. Exon 1 and rts 5/1 minor contains a deletion of 120 bp, without destroying the open reading frame, which is flanked by short direct repeats, 15 bp in length. The first two nucleotides of the intronic sequence were identified as GA and, therefore, do not agree with the donor consensus sequence. From the analysis of mouse x rat cell hybrids, the rts 5/1 major gene has been assigned to chromosome 7. By immunoblotting and immunocytochemistry, it was demonstrated that the isolated gene encodes a major protein of rat sperm outer dense fibres.

Expression of a histone H1 gene (H1.1) in human testis and Hassall's corpuscles of the thymus. Expression of a histone H1 gene (H1.1).

The expression of a H1 gene (H1.1) was studied in several human tissues. Northern blot analysis revealed that this gene is expressed in testis and thymus, but not in other human tissues like liver, spleen, lung, brain, thyroid gland and skin fibroblasts. Furthermore in situ hybridization on tissue sections revealed a cell type specific expression of histone H1.1 gene in the Hassall's corpuscles of the thymus.