ZFP628 Is a TAF4b-Interacting Transcription Factor Required for Mouse Spermiogenesis

TAF4b is a subunit of the TFIID complex that is highly expressed in the ovary and testis and required for mouse fertility. TAF4b-deficient male mice undergo a complex series of developmental defects that result in the inability to maintain long-term spermatogenesis. To decipher the transcriptional mechanisms upon which TAF4b functions in spermatogenesis, we used two-hybrid screening to identify a novel TAF4b-interacting transcriptional cofactor, ZFP628. Deletion analysis of both proteins reveals discrete and novel domains of ZFP628 and TAF4b protein that function to bridge their direct interaction in vitro Moreover, coimmunoprecipitation of ZFP628 and TAF4b proteins in testis-derived protein extracts supports their endogenous association. Using CRISPR-Cas9, we disrupted the expression of ZFP628 in the mouse and uncovered a postmeiotic germ cell arrest at the round spermatid stage in the seminiferous tubules of the testis in ZFP628-deficient mice that results in male infertility. Coincident with round spermatid arrest, we find reduced mRNA expression of transition protein (Tnp1 and Tnp2) and protamine (Prm1 and Prm2) genes, which are critical for the specialized maturation of haploid male germ cells called spermiogenesis. These data delineate a novel association of two transcription factors, TAF4b and ZFP628, and identify ZFP628 as a novel transcriptional regulator of stage-specific spermiogenesis.

Impact of protamine I on colon cancer proliferation, invasion, migration, diagnosis and prognosis

This paper investigates protamine I (PRM1) expression and its effects on proliferation, invasion and migration of colon cancer cells as well as its function in clinical diagnosis and prognosis. Gene chips were used to screen differentially expressed genes. PRM1 expression was detected by Western blotting and quantitative real time-polymerase chain reaction (qRT-PCR). Hematoxylin and eosin (HE) staining and immunohistochemistry were utilized to compare the expression of PRM1 from multiple differentiation levels of colon cancer tissues. Cell viability, cell apoptosis and cell cycle were tested using the MTT assay and flow cytometry. Cell invasion and migration capability were tested using the Transwell assay and wound healing. In vivo effects of PRM1 on colon cancer were explored using a xenograft model. PRM1 expression in serum was detected by enzyme-linked immunosorbent assay (ELISA). The expression level of PRM1 was significantly higher in colon cancer tissues and the staining degree of PRM1 in poorly-differentiated was stronger. pcDNA3.1-PRM1 decreased cell apoptosis while it increased the proliferation, cell invasion and migration. The si-PRM1 group displayed an opposite tendency. The serum PRM1 level was significantly higher and could serve as a diagnostic biomarker for colon cancer.

PiggyBac transposon-based polyadenylation-signal trap for genome-wide mutagenesis in mice

We designed a new type of polyadenylation-signal (PAS) trap vector system in living mice, the piggyBac (PB) (PAS-trapping (EGFP)) gene trapping vector, which takes advantage of the efficient transposition ability of PB and efficient gene trap and insertional mutagenesis of PAS-trapping. The reporter gene of PB(PAS-trapping (EGFP)) is an EGFP gene with its own promoter, but lacking a poly(A) signal. Transgenic mouse lines carrying PB(PAS-trapping (EGFP)) and protamine 1 (Prm1) promoter-driven PB transposase transgenes (Prm1-PBase) were generated by microinjection. Male mice doubly positive for PB(PAS-trapping (EGFP)) and Prm1-PBase were crossed with WT females, generating offspring with various insertion mutations. We found that 44.8% (26/58) of pups were transposon-positive progenies. New transposon integrations comprised 26.9% (7/26) of the transposon-positive progenies. We found that 100% (5/5) of the EGFP fluorescence-positive mice had new trap insertions mediated by a PB transposon in transcriptional units. The direction of the EGFP gene in the vector was consistent with the direction of the endogenous gene reading frame. Furthermore, mice that were EGFP-PCR positive, but EGFP fluorescent negative, did not show successful gene trapping. Thus, the novel PB(PAS-trapping (EGFP)) system is an efficient genome-wide gene-trap mutagenesis in mice.

[Protamine gene polymorphisms and male infertility]

Protamine (PRM) is one of the most abundant arginine-rich nucleoproteins in sperm and plays an important role in spermatogenesis. In the late stage of spermatogenesis, the replacement of PRM by histone prompts the closer combination between the nuclear matrix of sperm and nucleoprotein in order for high enrichment and condensation of nuclear chromatin in addition to preventing the sperm genome from mutation induced by internal and external factors. With the development of DNA sequencing techniques, researches on the association between PRM polymorphisms and male fertility are surfacing as a hot field. Many studies show that rs2301365 polymorphism is a risk factor for male infertility and increases the risk of male infertility by 27 - 66%, that rs737008 polymorphism of PRM1 and rs1646022 polymorphism of PRM2 are protective factors against Asian infertility, and that the ratio of PRM1 to PRM2 is intensively associated with male infertility. This review presents an update on the association between PRM gene polymorphisms and male infertility.

Oncomodulin/truncated protamine-mediated Nogo-66 receptor small interference RNA delivery promotes axon regeneration in retinal ganglion cells

The optic nerve often suffers regenerative failure after injury, leading to serious visual impairment such as glaucoma. The main inhibitory factors, including Nogo-A, oligodendrocyte myelin glycoprotein, and myelin-associated glycoprotein, exert their inhibitory effects on axonal growth through the same receptor, the Nogo-66 receptor (NgR). Oncomodulin (OM), a calcium-binding protein with a molecular weight of an ∼12 kDa, which is secreted from activated macrophages, has been demonstrated to have high and specific affinity for retinal ganglion cells (RGC) and promote greater axonal regeneration than other known polypeptide growth factors. Protamine has been reported to effectively deliver small interference RNA (siRNA) into cells. Accordingly, a fusion protein of OM and truncated protamine (tp) may be used as a vehicle for the delivery of NgR siRNA into RGC for gene therapy. To test this hypothesis, we constructed OM and tp fusion protein (OM/tp) expression vectors. Using the indirect immunofluorescence labeling method, OM/tp fusion proteins were found to have a high affinity for RGC. The gel shift assay showed that the OM/tp fusion proteins retained the capacity to bind to DNA. Using OM/tp fusion proteins as a delivery tool, the siRNA of NgR was effectively transfected into cells and significantly down-regulated NgR expression levels. More importantly, OM/tp-NgR siRNA dramatically promoted axonal growth of RGC compared with the application of OM/tp recombinant protein or NgR siRNA alone in vitro. In addition, OM/tp-NgR siRNA highly elevated intracellular cyclic adenosine monophosphate (cAMP) levels and inhibited activation of the Ras homolog gene family, member A (RhoA). Taken together, our data demonstrated that the recombinant OM/tp fusion proteins retained the functions of both OM and tp, and that OM/tp-NgR siRNA might potentially be used for the treatment of optic nerve injury.

An acute exposure to glyphosate-based herbicide alters aromatase levels in testis and sperm nuclear quality

Roundup is the major pesticide used in agriculture worldwide; it is a glyphosate-based herbicide. Its molecular effects are studied following an acute exposure (0.5%) of fifteen 60-day-old male rats during an 8-day period. Endocrine (aromatase, estrogen and androgen receptors, Gper1 in testicular and sperm mRNAs) and testicular functions (organ weights, sperm parameters and expression of the blood-testis barrier markers) were monitored at days 68, 87, and 122 after treatment, spermiogenesis and spermatogenesis. The major disruption is an increase of aromatase mRNA levels at least by 50% in treated rats at all times, as well as the aromatase protein. We have also shown a similar increase of Gper1 expression at day 122 and a light modification of BTB markers. A rise of abnormal sperm morphology and a decrease of the expression of protamine 1 and histone 1 testicular in epididymal sperm are observed despite a normal sperm concentration and motility.

Generation of mutant mice by pronuclear injection of circular plasmid expressing Cas9 and single guided RNA

CRISPR/Cas mediated genome editing has been successfully demonstrated in mammalian cells and further applications for generating mutant mice were reported by injecting humanized Cas9 (hCas) mRNA and single guide RNA into fertilized eggs. Here we inject the circular plasmids expressing hCas9 and sgRNA into mouse zygotes and obtained mutant mice within a month. When we targeted the Cetn1 locus, 58.8% (10/17) of the pups carried the mutations and six of them were homozygously mutated. Co-injection of the plasmids targeting different loci resulted in the successful removal of the flanked region in two out of three mutant pups. The efficient mutagenesis was also observed at the Prm1 locus. Among the 46 offspring carrying CRISPR/Cas plasmid mediated mutations, only two of them carried the hCas9 transgene. The pronuclear injection of circular plasmid expressing hCas9/sgRNA complex is a rapid, simple, and reproducible method for targeted mutagenesis.

The transacting factor CBF-A/Hnrnpab binds to the A2RE/RTS element of protamine 2 mRNA and contributes to its translational regulation during mouse spermatogenesis

During spermatogenesis, mRNA localization and translation are believed to be regulated in a stage-specific manner. We report here that the Protamine2 (Prm2) mRNA transits through chromatoid bodies of round spermatids and localizes to cytosol of elongating spermatids for translation. The transacting factor CBF-A, also termed Hnrnpab, contributes to temporal regulation of Prm2 translation. We found that CBF-A co-localizes with the Prm2 mRNA during spermatogenesis, directly binding to the A2RE/RTS element in the 3′ UTR. Although both p37 and p42 CBF-A isoforms interacted with RTS, they associated with translationally repressed and de-repressed Prm2 mRNA, respectively. Only p42 was found to interact with the 5′cap complex, and to co-sediment with the Prm2 mRNA in polysomes. In CBF-A knockout mice, expression of protamine 2 (PRM2) was reduced and the Prm2 mRNA was prematurely translated in a subset of elongating spermatids. Moreover, a high percentage of sperm from the CBF-A knockout mouse showed abnormal DNA morphology. We suggest that CBF-A plays an important role in spermatogenesis by regulating stage-specific translation of testicular mRNAs.

During eukaryotic gene expression, a fraction of newly exported mRNA molecules is transported to the cellular periphery for translation. The underlying mechanisms are not fully understood even though they likely affect specialized functions in many cell types including oligodendrocyets, neurons and germ cells. We discovered that the heterogeneous nuclear ribonucleoprotein CBF-A, interacts with a conserved sequence, the RNA trafficking sequence (RTS), located in the untranslated region of transported mRNAs. This interaction facilitates transport of myelin basic protein mRNA and dendritic mRNAs in oligodendrocytes and neurons, respectively. Here we investigated whether RTS-recognition by CBF-A coordinates transport and localized translation of the Protamine 2 mRNA in spermatogenic cells. During spermatogenesis the Protamine 2 mRNAs is synthesized and kept in a silent form to be translated at later stages. We show that by interacting with the RTS of the Protamine 2 mRNA both CBF-A isoforms contribute to regulate the transcript at the translational level. In a CBF-A knockout mouse model, we demonstrate that the interplay between the CBF-A isoforms in translation regulation of the Protamine 2 mRNA and other testicular transcripts has an impact on spermatogenesis.

Sperm nuclear basic proteins of tunicates and the origin of protamines

Sperm nuclear basic proteins (SNBPs) are the chromosomal proteins that are found associated with DNA in sperm nuclei at the end of spermiogenesis. These highly specialized proteins can be classified into three major types: histone type (H-type), protamine-like type (PL-type), and protamine type (P-type). A hypothesis from early studies on the characterization of SNBPs proposed a mechanism for the vertical evolution of these proteins that involved an H1 → PL → P transition. However, the processes and mechanisms involved in such a transition were not understood. In particular, it was not clear how a molecular transition from a lysine-rich protein precursor (H1 histone) to the arginine-rich protamines might have taken place. In deuterostomes, the presence of SNBPs of the H-type in echinoderms and of protamines in the higher phylogenetic groups of vertebrates had long been known. The initial work on the characterization of tunicate SNBPs attempted to define the types and range of SNBPs that characterize this phylogenetically intermediate group. It was found that tunicate SNBPs belong to the PL-type. In this work we discuss how the study of SNBPs in the tunicates has been key to providing support to the H1 → PL → P transition. Most significantly, it was in tunicates that a potential molecular mechanism to explain the lysine-to-arginine transition was first reported.

Effect of Vasectomy on Sperm Nuclear Chromatin Condensation in the Rabbit

Histone-to-protamine exchange in haploid spermatids is known to play a central role for male fertility. The present study investigates, for the first time, the effects of vasectomy on the expression of protamines in the rabbit. During normal spermatogenesis, protamine-1 and protamine-2 mRNA were expressed from step 5 round spermatids to step 11 elongated spermatids. In unilaterally vasectomized animals, control testes revealed normal spermatogenesis with normal protamine expression, while vasectomized testes exhibited both normal spermatogenesis and spermatogenic arrest. Some testes with normal spermatogenesis revealed delayed expression of both protamine-1 and protamine-2. Furthermore, multinucleated round spermatids were a regular finding in these testes. In both treated and untreated animals, a higher percentage of spermatozoa from the cauda epididymis had highly condensed chromatin when compared with those from the testis. The percentage of spermatozoa with highly condensed chromatin from testes and epididymides from the vasectomized side of treated animals remained unchanged from controls. As the integrity of nuclear chromatin is important for oocyte fertilization, especially in intracytoplasmic sperm injection (ICSI), where most of the natural selection mechanisms are bypassed, our data add valuable information for the treatment of infertility by ICSI, showing that vasectomy may affect nuclear chromatin integrity of testicular spermatids but not epididymal spermatozoa. Microsurgical epididymal sperm aspiration (MESA), therefore, may be superior to testicular sperm extraction (TESE) in vasectomized patients.

Protamine-like proteins in 12 sequenced species of Drosophila

The current study was aimed at analyzing putative protein sequences of the protamine-like proteins of 12 Drosophila species based on the reference sequences of two protamine-like proteins (Mst35Ba and Mst35Bb) found in Drosophila melanogaster sperm nuclei. Protamine-like proteins belong to a larger group of proteins that are involved in DNAbinding known as sperm nuclear basic proteins (SNBPs). SNBPs play a role in chromatin condensation during the postmeiotic stage of spermatogenesis, termed spermiogenesis. During spermiogenesis, nuclear transformation occurs where histones are exchanged for SNBPs, the chromatin condenses, and the nucleus transforms into a needle-like shape in Drosophila. Our goal was to search the 12 sequenced Drosophila genomes for protamine-like proteins based on the known sequences for D. melanogaster. Searches were performed on genomic DNA, mRNA transcripts and amino acid sequences using NCBI basic local alignment search tool (BLAST). Sequence alignments and analysis of amino acid content indicate that homologs for Mst35Ba and Mst35Bb are present in all 12 species of flies analyzed in this study. Functional analyses of a conserved region found within the proteins indicate the presence of a DNA-binding domain, possibly a high mobility group DNA- binding box. This study represents the first large-scale, single-genus dataset for protamine-like proteins and provides the basis for a fine-grained analysis of their evolution.

Protamine-1 and -2 polymorphisms and gene expression in male infertility: an Italian study

BACKGROUND

Correct histone/protamine replacement is an important stage in chromatin condensation during spermiogenesis in humans. There are two types of protamines: protamine 1 (P1) and the protamine 2 family (P2, P3, and P4), coded by the genes PRM1 and PRM2.

AIM

We analyze the sequences and gene expression of PRM1 and PRM2 and their relationship with defective spermatogenesis.

MATERIALS AND METHODS

Sequence analysis was carried out on 163 patients attending our laboratory for analysis of seminal fluid. Patients were divided into three groups: normozoospermic (53), teratozoospermic (60), and azoospermic (50). Gene expression was analyzed in seven patients with azoospermia and one with cryptozoospermia.

RESULTS

Seven single nuclotide polymorphisms (SNP) were identified: G54A, G102T and C230A for PRM1, and C246T, G288C, G298C and C373A for PRM2. For C230A, the CA genotype was present in 38% of teratozoospermic vs 55% of normozoospermic and 64% of azoospermic patients; for C373A, CA was found in 37% of teratozoospermic vs 47% of normozoospermic and 64% of azoospermic patients. In contrast, for G298C, GC was more common in the teratozoospermic (63%) than in the normozoospermic (49%) or azoospermic (48%) groups. These differences could suggest a greater susceptibility of these patients to abnormal sperm morphology. In five patients the levels of transcripts were reduced with respect to the control.

CONCLUSION

These data suggest that premeiotic arrest is associated with extremely reduced protamine expression. New studies of both PRM1 and PRM2 and their mRNA expression could help us better understand the molecular mechanisms underlying the protamine transcription and translation processes.

[Association of PRM1-190C- > A polymorphism with teratozoospermia]

OBJECTIVE

To investigate the association of single nucleotide polymorphism (SNP) of the Protamine 1 (PRM1) gene in infertile men with teratozoospermia.

METHODS

We collected semen samples from 157 infertile men with teratozoospermia (case group) and 37 age-matched male volunteers (control group), and subjected them to morphological analysis. We extracted genome DNA, genotyped the polymorphism of the PRM1-190C- > A SNP (rs2301365) using the Sequenom MassARRAY system, compared the genotype frequencies between the case and control groups, and analyzed the sperm morphological parameters of different genotypes in the infertile males with teratozoospermia.

RESULTS

The frequencies of the genotypes CC, CA and AA were 38.9% (61), 44.6% (70) and 16.6% (26) in the case group, as compared with 45.9% (17), 51.4% (19) and 2.7% (1) in the control, with that of AA significantly higher in the patients than in the volunteers (P<0.05). The frequencies of the alleles C and A were 57.6% and 42.4% in the former, with no significant differences from 71.6% and 28.4% in the latter (P>0.05). Nor were any statistically significant differences observed in sperm morphology parameters between the genotype CC and CA, AA and CA + AA in the male patients (P>0.05).

CONCLUSION

The SNP of PRM1-190C- > A might be associated with teratozoospermia-induced male infertility in the Han Chinese. Although this SNP may attribute to abnormal sperm morphology, the targeted part of sperm remains unclear.

Evaluation of mRNA marker specificity for the identification of five human body fluids by capillary electrophoresis

The identification of forensically relevant human body fluids through messenger RNA (mRNA) profiling is of interest to the forensic community. Previous studies have proposed several tissue-specific mRNA markers to achieve this goal. Seven markers for the following genes were selected for evaluation in this study: histatin 3 (HTN3) and statherin (STATH) for saliva, mucin 4 (MUC4) for vaginal secretions, matrix metalloproteinase 7 (MMP7) for menstrual blood, delta-aminolevulinate synthase 2 (ALAS2) for peripheral blood, and protamine 2 (PRM2) and transglutaminase 4 (TGM4) for semen. The expression of these markers was examined in each body fluid. All mRNA markers were present in their target body fluids. Peripheral blood and saliva showed little cross-reactivity with the selected markers. However, a high level of cross-reactivity was observed between the vaginal secretion marker MUC4 and saliva stains. Semen showed a high level of cross-reactivity with the selected markers. Co-expression of the predicted body fluid markers was detected in menstrual blood and vaginal secretion stains. The expression pattern of these mRNA markers varied through the menstrual cycle time points tested. Differences in gene expression levels and marker cross-reactivity were observed in the donors tested. Despite the presence of cross-reactivity and co-expression, each of the body fluids examined have distinct gene expression profiles, allowing for body fluid identification based on mRNA profiling.

Cannabinoid receptor 1 influences chromatin remodeling in mouse spermatids by affecting content of transition protein 2 mRNA and histone displacement

Marijuana smokers and animals treated with Δ9-tetrahydrocannabinol, the principal component of marijuana, show alterations of sperm morphology suggesting a role for cannabinoids in sperm differentiation and/or maturation. Because the cannabinoid receptor 1 (CNR1) activation appears to play a pivotal role in spermiogenesis, the developmental stage where DNA is remodeled, we hypothesized that CNR1 receptors might also influence chromatin quality in sperm. We used Cnr1 null mutant (Cnr1-/-) mice to study the possible role of endocannabinoids on sperm chromatin during spermiogenesis. We demonstrated that CNR1 activation regulated chromatin remodeling of spermatids by either increasing Tnp2 levels or enhancing histone displacement. Comparative analysis of wild-type, Cnr1+/-, and Cnr1-/- animals suggested the possible occurrence of haploinsufficiency for Tnp2 turnover control by CNR1, whereas histone displacement was disrupted to a lesser extent. Furthermore, flow cytometry analysis demonstrated that the genetic loss of Cnr1 decreased sperm chromatin quality and was associated with sperm DNA fragmentation. This damage increased during epididymal transit, from caput to cauda. Collectively, our results show that the expression/activity of CNR1 controls the physiological alterations of DNA packaging during spermiogenesis and epididymal transit. Given the deleterious effects of sperm DNA damage on male fertility, we suggest that the reproductive function of marijuana users may also be impaired by deregulation of the endogenous endocannabinoid system.

Mitochondrial and nuclear markers suggest Hanuman langur (Primates: Colobinae) polyphyly: implications for their species status

Recent molecular studies on langurs of the Indian subcontinent suggest that the widely-distributed and morphologically variable Hanuman langurs (Semnopithecus entellus) are polyphyletic with respect to Nilgiri and purple-faced langurs. To further investigate this scenario, we have analyzed additional sequences of mitochondrial cytochrome b as well as nuclear protamine P1 genes from these species. The results confirm Hanuman langur polyphyly in the mitochondrial tree and the nuclear markers suggest that the Hanuman langurs share protamine P1 alleles with Nilgiri and purple-faced langurs. We recommend provisional splitting of the so-called Hanuman langurs into three species such that the taxonomy is consistent with their evolutionary relationships.

Conservation of the PRM1→PRM2→TNP2 Domain

In mouse and human, the genes encoding protamines PRM1, PRM2 and transition protein TNP2 are found clustered together on chromosome 16. In addition, these three genes lie in the same orientation to one another and are coordinately expressed in a haploid-specific manner during spermatogenesis. Previously, we have shown that the human PRM1 --> PRM2 --> TNP2 locus exists as a single chromatin domain bounded by two male germ cell-specific MARs, i.e. Matrix Attachment Regions. A third, somatic-specific MAR element lies immediately 3' of the PRM1 --> PRM2 --> TNP2 domain. This MAR maps to a conserved CpG island 5' of the human SOCS-1 gene. Similarly, two candidate MARs flank the mouse Prm1 --> Prm2 --> Tnp2 domain. Comparative analysis of the mouse and human promoter regions identified several conserved regulatory motifs for each of the genes of this cluster. This further establishes the synteny of this region. Global structural similarities and the functional relevance of the associated candidate regulatory elements are discussed.

Pregnancy-specific {beta}-1-glycoprotein 1 and human leukocyte antigen-E mRNA in human sperm: differential expression in fertile and infertile men and evidence of a possible functional role during early development

BACKGROUND

Mature spermatozoa contain thousands of mRNA transcripts. It has been recently shown that human sperm can deliver RNA into the oocyte, suggesting that mRNAs might have a role before or after fertilization. Human embryos express PSG1 (pregnancy-specific beta-1-glycoprotein 1) and HLA-E (human leukocyte antigen-E), molecules playing a role in implantation and early development. We compared PSG1 and HLA-E sperm mRNA levels in fertile and infertile men and we tested the hypothesis that these transcripts are selectively retained in the newly formed zygote.

METHODS

Real-time RT-PCR was used to analyze sperm mRNA levels (n = 11 fertile, n = 31 infertile patients) of PSG1, HLA-E and PRM2 (protamine 2). The presence of PSG1 and HLA-E proteins was evaluated by western blot in sperm protein extracts (n = 3). Using ICSI of human sperm into hamster oocytes we evaluated the permanence of these mRNAs at different time points (n = 10 for each time) after fertilization.

RESULTS

PSG1, HLA-E and PRM2 transcripts were demonstrated in ejaculated sperm. The fertile group showed significantly higher levels of PSG1 and HLA-E mRNA (both P < 0.05) than the infertile group, whereas PRM2 levels were not significantly different. However, PSG1 and HLA-E proteins were not found in ejaculated sperm. Following ICSI, PRM2 was undetectable after fertilization; conversely, PSG1 and HLA-E transcripts remained detectable for at least 24 h of zygotic development.

CONCLUSIONS

We provide new evidence that indicates that human sperm deliver transcripts that may have a role in early embryo development and decreased levels of these transcripts may be associated with infertility.

Chemical genetic screening identifies tricyclic compounds that decrease cellular melanin content

A screen of a library of 2,000 drugs and natural products in murine melanocytes identified 10 tricyclic antidepressants (TCAs) as compounds that potently decreased intracellular melanin content. The rank order of potency of these compounds for decreasing melanin content was different than their relative potencies as antidepressants. These compounds had no effect on either the level or the enzymatic activity of cellular tyrosinase (Tyr). Increased presence of both Tyr and melanin in the culture media was observed in treated melanocytes. Immunofluorescence localization revealed that these compounds decreased intracellular melanin content by disrupting the intracellular trafficking of Tyr gene family proteins. In treated melanocytes, Tyr, Tyr-related protein 1, and dopachrome tautomerase accumulated in enlarged granules distributed throughout the cytoplasm. Colocalization of Tyr with lysosome-associated membrane protein 1 was observed within many of these granules. Partial colocalization of Tyr with the Hermansky-Pudlak syndrome 1 gene product observed in control melanocytes was abolished by TCA treatment. Our results show that these compounds decreased intracellular melanin content by altering the trafficking of Tyr gene family proteins and inducing abnormal secretion of Tyr. Results from our screening have implications for the design of products for skin lightening and treatment of hyperpigmentation.

Nuclear organization of the protamine locus

The human protamine gene cluster consists of three tightly regulated genes, protamine 1 (PRM1), protamine 2 (PRM2) and transition protein 2 (TNP2). Their products are required to repackage the paternal genome during spermiogenesis into a functional gamete. They reside within a single DNase I-sensitive domain associated with the sperm nuclear matrix, bounded by two haploid-specific Matrix Attachment Regions. The nuclear matrix is a dynamic proteinaceous network that is associated with both transcription and replication. While substantial effort has been directed toward pre- and post-transcriptional regulation, the role of the nuclear matrix in regulating haploid expressed genes has received comparatively little attention. In this regard, the functional organization of the human PRM1 --> PRM2 --> TNP2 cluster and where appropriate, comparisons to other model systems will be considered.

mRNA profiling for body fluid identification by multiplex quantitative RT-PCR

An alternative approach to conventional protein-based body fluid identification is gene expression profiling analysis. In the present work, we report the development of sensitive and robust multiplex quantitative reverse transcriptase-PCR assays for the identification of blood, saliva, semen, and menstrual blood. Each body fluid assay comprises a triplex system that detects transcripts from two body fluid-specific genes and a housekeeping gene GAPDH. The body fluid-specific genes include erythroid delta-aminolevulinate synthase (ALAS2) and beta-spectrin (SPTB) for blood, statherin (STATH) and histatin 3 (HTN3) for saliva, protamine 1 (PRM1) and protamine 2 (PRM2) for semen, and matrix metalloproteinase 7 (MMP7) and matrix metalloproteinase 10 (MMP10) for menstrual blood. Normalization of both body fluid-specific genes to the housekeeping gene by means of appropriate cycle threshold metrics ensures the high specificity of each assay for its cognate body fluid.

Genetic risk factors in male infertility

The etiopathogenesis of testicular failure remains unknown in about half of the cases and is referred to as "idiopathic infertility". "Idiopathic" testicular failure is of probable genetic origin since the number of genes involved in human spermatogenesis is likely thousands and only a small proportion of them have been identified and screened in infertile men. In parallel with studies aimed to identify mutations with a clear cause-effect relationship in spermatogenesis candidate genes, there is an increasing interest towards genetic susceptibility factors to male infertility. Despite many efforts, only a few clinically relevant polymorphisms have been identified. This is mainly related to the multifactorial nature of male infertility and to the inappropriate study design of the majority of the studies. The most promising polymorphisms are in genes involved in the endocrine regulation of spermatogenesis and on the Y chromosome, the "gr/gr" deletions. Polymorphisms are generally considered as co-factors. Their final effect on testis function and fertility is probably modulated by the genetic background of each individual and/or by the presence of certain environmental factors. In this review, recent findings concerning some of the most widely studied polymorphisms and male infertility will be discussed.