The mouse transition protein 1 gene contains a B1 repetitive element and is located on chromosome 1

Regeneration of Leydig cells in ectopically autografted adult mouse testes

Ectopic autografting of testis tissue is a promising approach for studying testicular development, male germline preservation and restoration of male fertility. In this study, we examined the fate of various testicular cells in adult mouse testes following ectopic autografting at 1, 2, 4 and 8 weeks post grafting. Histological examination showed no evidence of re-establishment of spermatogenesis in autografts, and progressive degeneration of seminiferous tubules was detected. Expression of germ cell-specific proteins such as POU5F1, DAZL, TNP1, TNP2, PRM1 and PRM2 revealed that, although proliferating and differentiating spermatogenic germ cells such as spermatogonia, spermatocytes and spermatids could survive in autografts until 4 weeks, only terminally differentiated germ cells such as sperm persisted in autografts until 8 weeks. The presence of Sertoli and peritubular myoid cells, as indicated by expression of WT1 and ACTA2 proteins, respectively, was evident in the autografts until 8 weeks. Interestingly, seminal vesicle weight and serum testosterone level were restored in autografted mice by 8 weeks post grafting. The expression of Leydig cell-specific proteins such as CYP11A1, HSD3B2 and LHCGR showed revival of Leydig cell (LC) populations in autografts over time since grafting. Elevated expression of PDGFRA, LIF, DHH and NEFH in autografts indicated de novo regeneration of LC populations. Autografted adult testis can be used as a model for investigating Leydig cell regeneration, steroidogenesis and regulation of the intrinsic factors involved in Leydig cell development. The success of this rodent model can have therapeutic applications for adult human males undergoing sterilizing cancer therapy.

Reduction of spermatogenesis but not fertility in Creb3l4-deficient mice

Creb3l4 belongs to the CREB/ATF family of transcription factors that are involved in mediating transcription in response to intracellular signaling. This study shows that Creb3l4 is expressed at low levels in all organs and in different stages of embryogenesis but is present at very high levels in the testis, particularly in postmeiotic male germ cells. In contrast to CREB3L4 in the human prostate, of which specific expression was detected, Creb3l4 transcripts in the mouse prostate could be detected only by RT-PCR. To identify the physiological function of Creb3l4, the murine gene was inactivated by replacement with the gene encoding green fluorescent protein. Surprisingly, Creb3l4-deficient mice were born at expected ratios, were healthy, and displayed normal long-term survival rates. Despite a significant reduction in the number of spermatozoa in the epididymis of Creb3l4(-)(/)(-) mice, the breeding of mutant males with wild-type females was productive and the average litter size was not significantly altered in comparison to wild-type littermates. Further analyses revealed that the seminiferous tubules of Creb3l4(-)(/)(-) mice contained all of the developmental stages, though there was evidence for increased apoptosis of meiotic/postmeiotic germ cells. These results suggest that Creb3l4 plays a role in male germ cell development, but its loss is insufficient to completely compromise the production of spermatozoa.

A transgenic analysis of mouse lactate dehydrogenase C promoter activity in the testis

Transcription of the mouse testis-specific lactate dehydrogenase c (mldhc) gene is limited to cells of the germinal epithelium. Cloning and analysis of the mldhc promoter revealed that a 100-bp core promoter was able to regulate testis-specific transcription in vitro and in transgenic mice. Surprisingly, expression of the reporter in transgenic testes was limited to pachytene spermatocytes, whereas native LDH-C(4) was detected in pachytene and all later germ cells. To locate additional regulatory sequence that could recapitulate the native LDH-C(4) distribution pattern, we investigated the contribution of 5' and 3' flanking sequences to the regulation of LDH-C(4) expression. We found that transcription factor YY1 binds to the mldhc promoter, that the mldhc 3' untranslated sequence does not permit a postmeiotic expression of a beta-galactosidase reporter in transgenic mice, and that native mldhc mRNA is predominately meiotic, with only a low level of postmeiotic distribution. Our results suggest that the high level of LDH-C(4) in postmeiotic cells results from mRNA and protein stability.

Condensation of DNA by spermatid basic nuclear proteins

Two transition proteins, TP1 and TP2, participate in the repackaging of the spermatid genome early in mammalian spermiogenesis, coincident with the first detectable changes in chromatin condensation. Using an optical trap and a two-channel flow cell to move single DNA molecules into buffer containing protein, we have measured the rates of DNA condensation and decondensation induced by the binding of Syrian hamster transition proteins TP1 and TP2 and protamines P1 and P2. The results show that both transition proteins condense free DNA, with rates similar to those of protamine 1 and 2. DNA molecules condensed with TP1 were significantly less stable than DNA condensed by protamine or by TP2. Experiments conducted with a peptide corresponding to the C-terminal 25 residues of TP2 showed that this domain is responsible for condensing DNA. Experiments conducted with two fragments of TP1 containing arginine and lysine residues demonstrated that DNA binding by TP1 must involve more than these basic sequences. Zinc facilitated the condensation of DNA by P2 but not by TP2. The dissociation rates of TP2 and P2 from DNA were not affected by the addition of zinc.

Yeast one-hybrid assay identifies YY1 as a binding factor for a proacrosin promoter element

The proacrosin gene is specifically expressed in the testis and encodes an acrosomal enzyme. Previously, footprint analyses have shown binding of nuclear extracts from testis and brain to a highly conserved 17 bp motif (F1 element: 5'-AACTTCAAAATGGCTCC/T-3') located in the proacrosin promoter. By using this DNA-element as a target in a yeast one-hybrid assay, a cDNA fragment coding for the C-terminal part of the transcription factor YY1 was isolated. The binding of YY1 to this F1 element was confirmed by immunocompetition in EMSA. Because putative YY1 binding sites were also found in the promoters of other testis-specific genes, the YY1 transcription factor could play an important role in testicular gene expression.

The murine dilute suppressor gene encodes a cell autonomous suppressor

The murine dilute suppressor gene (dsu) suppresses the coat-color phenotype of three pigment mutations, dilute (d), ashen (ash) and leaden (ln), that each produce adendritic melanocytes. Suppression is due to the ability of dsu to partially restore (ash and ln), or almost completely restore (d), normal melanocyte morphology. While the ash and ln gene products have yet to be identified, the d gene encodes a novel myosin heavy chain (myosin 12), which is speculated to be necessary for the elaboration, maintenance, and/or function of melanocyte cell processes. To begin to discriminate between different models of dsu action, we have produced aggregation chimeras between mice homozygous for dsu and mice homozygous for d to determine if dsu acts cell autonomously or cell nonautonomously. In addition, we have further refined the map location of dsu in order to examine a number of possible dsu candidate genes mapping in the region and to provide a genetic basis for the positional cloning of dsu.

Identification of conserved potential regulatory sequences of the protamine-encoding P1 genes from ten different mammals

In order to detect regulatory conserved DNA elements within the protamine 1-encoding gene (P1) promoter, we have sequenced this region from the rat, guinea pig, gorilla, orangutan, anubis baboon and red monkey P1 genes and compared it to the homologous human, bull, boar and mouse nucleotide (nt) sequences. We demonstrate the presence of a consensus sequence, HSMCYTCAYAAT (Prot1C: protamine 1 consensus), from nt position -64 to position -53 in all P1 genes whose promoter sequences are now known. We also show that sequences similar to Prot1C are found in the promoter region of other testis-specific genes, such as the transition protein 1-encoding gene promoter which is thought to have derived from the P1 genes. The relevance of this conserved element in the expression of P1 genes is strongly supported by the recent demonstration of a mouse testis trans-acting factor [Tet-1; Tamura et al., J. Biol. Chem. 267 (1992) 4327-4332] which binds and matches in the mouse the first 11 bp of the corresponding consensus Prot1C sequence reported here. Another highly conserved element (TGTGAGG) has been identified 20 +/- 3 nt upstream from Prot1C. This sequence forms a perfect palindrome with the central 7 nt of Prot1C and is absent in the homologous region of other genes. Further upstream, at positions -113 to -132, a third highly conserved region is present (MATGCCCATATWTGGRCAYG) which is similar to the c-fos SRE (serum-response element) and contains the central core common to all SREs. This element has not been found in the homologous region of other sperm-specific genes.(ABSTRACT TRUNCATED AT 250 WORDS)

The gene for human transition protein 2: nucleotide sequence, assignment to the protamine gene cluster, and evidence for its low expression

We have isolated the gene for transition protein 2 (TNP2) from a human cosmid clone that contains the genes for protamines 1 and 2. A nucleotide sequence of 1776 bp that comprises 268 bp of the 5'-noncoding region, 400 bp of exon 1, 849 bp of an intron, 17 bp of exon 2, and 242 bp of the 3'-noncoding region was determined. A modified CAT box, a TATAA box, and two possible polyadenylation sites were identified. Transcripts in testicular RNA could be detected only by RT-PCR and RNase protection assays. By direct sequencing of the PCR products, a cDNA sequence was established. It can be deduced from these results that, in contrast to other mammalian genes, the human TNP2 gene is expressed at a very low level. The human gene differs from that of other mammalian species by the absence of a conserved GCCATCAC nucleotide sequence in the 3'-untranslated region. Since both protamine genes are known to be localized on chromosome 16p13.3, this chromosomal localization holds true for the human TNP2 gene as well. The genes for both protamines and TNP2 are arranged in a DNA stretch of 13 kb.

A linkage map of mouse chromosome 1 using an interspecific cross segregating for the gld autoimmunity mutation

An interspecific backcross was used to define a high resolution linkage map of mouse Chromosome (Chr) 1 and to analyze the segregation of the generalized lymphoproliferative disease (gld) mutation. Mice homozygous for gld have multiple features of autoimmune disease. Analysis of up to 428 progeny from the backcross [(C3H/HeJ-gld x Mus spretus)F1 x C3H/HeJ-gld] established a map that spans 77.6 cM and includes 56 markers distributed over 34 ordered genetic loci. The gld mutation was mapped to a less than 1 cM segment on distal mouse Chr 1 using 357 gld phenotype-positive backcross mice. A second backcross, between the laboratory strains C57BL/6J and SWR/J, was examined to compare recombination frequency between selected markers on mouse Chr 1. Significant differences in crossover frequency were demonstrated between the interspecific backcross and the inbred laboratory cross for the entire interval studied. Sex difference in meiotic crossover frequency was also significant in the laboratory mouse cross. Two linkage groups known to be conserved between segments of mouse Chr 1 and the long arm of human Chrs 1 and 2 where further defined and a new conserved linkage group was identified that includes markers of distal mouse Chr 1 and human Chr 1, bands q32 to q42.

Nucleotide sequence and exon-intron structure of the bovine transition protein 1 gene

The nucleotide sequence and exon-intron structure of the bovine transition protein 1 gene was determined. It consists of 2 exons (E1, 139 bp; E2, 29 bp) and a single intron (220 bp). The position of the transcription initiation site was determined 30 nucleotides upstream of ATG. TAAATA- and CAAT-boxes were found 60 and 121 bp upstream of the ATG-translation start point, respectively. It was observed that transition protein 1 is highly conserved in mammals at the nucleotide as well as at the amino acid level.