Inhibition of hsp70-1 and hsp70-3 expression disrupts preimplantation embryogenesis and heightens embryo sensitivity to arsenic

Nuclear-localized eukaryotic translation initiation factor 1A is involved in mouse preimplantation embryo development

Preimplantation embryo development is characterized by drastic nuclear reprogramming and dynamic stage-specific gene expression. Key regulators of this earliest developmental stage have not been revealed. In the present study, a "non-classical" nuclear-localization pattern of eIF1A was observed during early developmental stages of mouse preimplantation embryo before late-morula. In particular, eIF1A is most highly expressed in the nuclear of 2-cell embryo. Knockdown eIF1A by siRNA microinjection affected the development of mouse preimplantation embryo, resulted in decreased blastocyst formation rate. CDX2 protein expression level significantly down-regulated after eIF1A knockdown in morula stage. In addition, the mRNA expression level of Hsp70.1 was also decreased in 2-cell embryo. The results indicate an indispensable role of eIF1A in mouse preimplantation embryos.

Distinct Gene Expression Patterns of Two Heat Shock Protein 70 Members During Development, Diapause, and Temperature Stress in the Freshwater Crustacean Daphnia magna

Dormancy is a lifecycle delay that allows organisms to escape suboptimal environmental conditions. As a genetically programmed type of dormancy, diapause is usually accompanied by metabolic depression and enhanced tolerance toward adverse environmental factors. However, the drivers and regulators that steer an organism’s development into a state of suspended animation to survive environmental stress have not been fully uncovered. Heat shock proteins 70 (HSP70s), which are often produced in response to various types of stress, have been suggested to play a role in diapause. Considering the diversity of the Hsp70 family, different family members may have different functions during diapause. In the present study, we demonstrate the expression of two hsp70 genes (A and B together with protein localization of B) throughout continuous and diapause interrupted development of Daphnia magna. Before and after diapause, the expression of Dmhsp70-A is low. Only shortly before diapause and during diapause, Dmhsp70-A is significantly upregulated and may therefore be involved in diapause preparation and maintenance. In contrast, Dmhsp70-B is expressed only in developing embryos but not in diapausing embryos. During continuous development, the protein of this Hsp70 family member is localized in the cytosol. When we expose both embryo types to heat stress, expression of both hsp70 genes increases only in developing embryos, and the protein of family member B is translocated to the nucleus. In this stress formation, this protein provides effective protection of nucleoplasmic DNA. As we also see this localization in diapausing embryos, it seems that Daphnia embryo types share a common subcellular strategy when facing dormancy or heat shock, i.e., they protect their DNA by HSP70B nuclear translocation. Our study underlines the distinctive roles that different Hsp70 family members play throughout continuous and diapause interrupted development.

The heat shock protein family gene Hspa1l in male mice is dispensable for fertility

Background

Heat shock protein family A member 1 like (Hspa1l) is a member of the 70kD heat shock protein (Hsp70) family. HSPA1L is an ancient, evolutionarily conserved gene with a highly conserved domain structure. The gene is highly abundant and constitutively expressed in the mice testes. However, the role of Hspa1l in the testes has still not been elucidated.

Methods

Hspa1l-mutant mice were generated using the CRISPR/Cas9 system. Histological and immunofluorescence staining were used to analyze the phenotypes of testis and epididymis. Apoptotic cells were detected through TUNEL assays. Fertility and sperm motilities were also tested. Quantitative RT-PCR was used for analyzing of candidate genes expression. Heat treatment was used to induce heat stress of the testis.

Results

We successfully generated Hspa1l knockout mice. Hspa1l ^-/- mice exhibited normal development and fertility. Further, Hspa1l ^-/- mice shown no significant difference in spermatogenesis, the number of apoptotic cells in testes epididymal histology, sperm count and sperm motility from Hspa1l ^+/+ mice. Moreover, heat stress does not exacerbate the cell apoptosis in Hspa1l ^-/- testes. These results revealed that HSPA1L is not essential for physiological spermatogenesis, nor is it involved in heat-induced stress responses, which provides a basis for further studies.

Use of two new formulations as bovine embryo manipulation solution

This study aimed to evaluate the effect of two Embryo Manipulation Solutions (EMS and EMS supplemented) in maintenance of the viability of embryos, initially using structures derived from mice (first phase). Next, the efficiency of these solutions in routines of bovine embryo transfer was evaluated (second stage). Mice embryos were used in the stages of early blastocyst, and compact morula grades I and II. These embryos were initially randomly distributed and maintained for four hours in three solutions: Modified phosphate buffered saline (PBS; Control); EMS (treatment 1), and EMS supplemented (treatment 2). Subsequently, they were cultured in TCM 199 medium and evaluated in terms of total number of cells, morphometric characteristics, ultra structural aspects, detection of cell apoptosis, and quantification of Hsp70.3 gene expression. In the second phase, these same solutions were tested in the transfer of quality I and II bovine embryos (excellent and good). These embryos were transferred fresh to 58 recipients. The results showed that the total number of cells in embryos expanded blastocyst (ExB), the number of apoptotic cells, the cell, nuclear, nucleolar diameter and the nucleus/nucleolus ratio was similar among the treatments. The pregnancy rate shown on second phase was also similar. However, the EMS supplemented expressed more Hsp70.3 than EMS. The expression of Hsp70.3 was also greater for embryos in EMS than that of EMS supplemented. The McII embryos, EMS and EMS supplemented samples also expressed more Hsp70.3 compared to control embryos. In conclusion, the tested solutions can be used in routine embryo transfer techniques, replacing modified PBS solution as an effective media in maintaining embryo viability.

A proteomic analysis on human sperm tail: comparison between normozoospermia and asthenozoospermia

PURPOSE

Asthenozoospermia is a common cause of human male infertility characterized by reduced sperm motility. The molecular mechanism that impairs sperm motility is not fully understood. This study proposed to identify novel biomarkers by focusing on sperm tail proteomic analysis of asthenozoospermic patients.

METHODS

Sperm were isolated from normozoospermic and asthenozoospermic semen samples. Tail fractions were obtained by sonication followed by Percoll gradient. The proteins were extracted by solubilization and subjected to two-dimensional gel electrophoresis (2-DE); then, the spots were analyzed using Image Master 2D Platinum software. The significantly increased/decreased amounts of proteins in the two groups were exploited by matrix-assisted laser desorption-ionization time-of-flight/time-of-flight (MALDI-TOF-TOF) mass spectrometry.

RESULTS

Three hundred ninety protein spots were detected in both groups. Twenty-one protein spots that had significantly altered amounts (p < 0.05) were excised and exploited using MALDI-TOF-TOF mass spectrometry. They led to the identification of the following 14 unique proteins: Tubulin beta 2B; glutathione S-transferase Mu 3; keratin, type II cytoskeletal 1; outer dense fiber protein 2; voltage-dependent anion-selective channel protein 2; A-kinase anchor protein 4; cytochrome c oxidase subunit 6B; sperm protein associated with the nucleus on the X chromosome B; phospholipid hydroperoxide glutathione peroxidase-mitochondrial; isoaspartyl peptidase/L-asparaginase; heat shock-related 70 kDa protein 2; stress-70 protein, mitochondrial; glyceraldehyde-3-phosphate dehydrogenase, testis-specific and clusterin.

CONCLUSION

Fourteen proteins present in different amounts in asthenozoospermic sperm tail samples were identified, four of which are reported here for the first time. These proteins might be used as markers for the better diagnosis of sperm dysfunctions, targets for male contraceptive development, and to predict embryo quality.

A novel acrosomal protein, IQCF1, involved in sperm capacitation and the acrosome reaction

On the basis of the unknown tags in the mature human sperm serial analysis of gene expression library constructed by our laboratory, some transcripts were cloned, including Iqcf1 (IQ motif containing F1). To investigate the function of sperm-retained Iqcf1 in spermatogenesis and fertilization of mice, we investigated the spatial and temporal expression of IQCF1. By using the (transcription activator-like effector nuclease) strategy, Iqcf1-knockout mice were produced, and the phenotypes of the Iqcf1(-/-) mice were analyzed. The results showed that IQCF1 was localized in the acrosome of spermatozoa and spermatids; the expression of IQCF1 in testes was associated with spermatogenic capacity. The Iqcf1(-/-) mice were significantly less fertile than the wild-type mice (p = 0.0057) because of reduced sperm motility (p = 0.0094) and the acrosome reaction (AR) (p = 0.0093). In spermatozoa, IQCF1 interacted with calmodulin (CaM) and possibly participated in the tyrosine phosphorylation of sperm proteins during capacitation. In conclusion, a newly identified acrosomal protein, IQCF1, is closely related to sperm capacitation and AR; in particular, it is involved in tyrosine phosphorylation of sperm proteins through interaction with CaM. Research into the function of IQCF1 during fertilization could facilitate the investigation of the molecular mechanism of capacitation, which is unclear.

Loss of the inducible Hsp70 delays the inflammatory response to skeletal muscle injury and severely impairs muscle regeneration

Skeletal muscle regeneration following injury is a highly coordinated process that involves transient muscle inflammation, removal of necrotic cellular debris and subsequent replacement of damaged myofibers through secondary myogenesis. However, the molecular mechanisms which coordinate these events are only beginning to be defined. In the current study we demonstrate that Heat shock protein 70 (Hsp70) is increased following muscle injury, and is necessary for the normal sequence of events following severe injury induced by cardiotoxin, and physiological injury induced by modified muscle use. Indeed, Hsp70 ablated mice showed a significantly delayed inflammatory response to muscle injury induced by cardiotoxin, with nearly undetected levels of both neutrophil and macrophage markers 24 hours post-injury. At later time points, Hsp70 ablated mice showed sustained muscle inflammation and necrosis, calcium deposition and impaired fiber regeneration that persisted several weeks post-injury. Through rescue experiments reintroducing Hsp70 intracellular expression plasmids into muscles of Hsp70 ablated mice either prior to injury or post-injury, we confirm that Hsp70 optimally promotes muscle regeneration when expressed during both the inflammatory phase that predominates in the first four days following severe injury and the regenerative phase that predominates thereafter. Additional rescue experiments reintroducing Hsp70 protein into the extracellular microenvironment of injured muscles at the onset of injury provides further evidence that Hsp70 released from damaged muscle may drive the early inflammatory response to injury. Importantly, following induction of physiological injury through muscle reloading following a period of muscle disuse, reduced inflammation in 3-day reloaded muscles of Hsp70 ablated mice was associated with preservation of myofibers, and increased muscle force production at later time points compared to WT. Collectively our findings indicate that depending on the nature and severity of muscle injury, therapeutics which differentially target both intracellular and extracellular localized Hsp70 may optimally preserve muscle tissue and promote muscle functional recovery.

Heat shock protein production and immunity and altered fetal development in diabetic pregnant rats

We evaluated associations between the concentrations of heat shock proteins (hsp60 and hsp70) and their respective antibodies, alterations in maternal reproductive performance, and fetal malformations in pregnant rats with hyperglycemia. Mild diabetes (MD) or severe diabetes (SD) was induced in Sprague-Dawley rats prior to mating; non-treated non-diabetic rats (ND) served as controls. On day 21 of pregnancy, maternal blood was analyzed for hsp60 and hsp70 and their antibodies; and fetuses were weighed and analyzed for congenital malformations. Hsp and anti-hsp levels were correlated with blood glucose levels during gestation. There was a positive correlation between hsp60 and hsp70 levels and the total number of malformations (R = 0.5908, P = 0.0024; R = 0.4877, P = 0.0134, respectively) and the number of malformations per fetus (R = 0.6103, P = 0.0015; R = 0.4875, P = 0.0134, respectively). The anti-hsp60 IgG concentration was correlated with the number of malformations per fetus (R = 0.3887, P = 0.0451) and the anti-hsp70 IgG level correlated with the total number of malformations (R = 0.3999, P = 0.0387). Moreover, both hsp and anti-hsp antibodies showed negative correlations with fetal weight. The results suggest that there is a relationship between hsp60 and hsp70 levels and their respective antibodies and alterations in maternal reproductive performance and impaired fetal development and growth in pregnancies associated with diabetes.

Multiple hsp70 isoforms in the eukaryotic cytosol: mere redundancy or functional specificity?

Hsp70 molecular chaperones play a variety of functions in every organism, cell type and organelle, and their activities have been implicated in a number of human pathologies, ranging from cancer to neurodegenerative diseases. The functions, regulations and structure of Hsp70s were intensively studied for about three decades, yet much still remains to be learned about these essential folding enzymes. Genome sequencing efforts revealed that most genomes contain multiple members of the Hsp70 family, some of which co-exist in the same cellular compartment. For example, the human cytosol and nucleus contain six highly homologous Hsp70 proteins while the yeast Saccharomyces cerevisiae contains four canonical Hsp70s and three fungal-specific ribosome-associated and specialized Hsp70s. The reasons and significance of the requirement for multiple Hsp70s is still a subject of debate. It has been postulated for a long time that these Hsp70 isoforms are functionally redundant and differ only by their spatio-temporal expression patterns. However, several studies in yeast and higher eukaryotic organisms challenged this widely accepted idea by demonstrating functional specificity among Hsp70 isoforms. Another element of complexity is brought about by specific cofactors, such as Hsp40s or nucleotide exchange factors that modulate the activity of Hsp70s and their binding to client proteins. Hence, a dynamic network of chaperone/co-chaperone interactions has evolved in each organism to efficiently take advantage of the multiple cellular roles Hsp70s can play. We summarize here our current knowledge of the functions and regulations of these molecular chaperones, and shed light on the known functional specificities among isoforms.

Hsp70 is required for optimal cell proliferation in mouse A6 mesoangioblast stem cells

Mouse Hsp70 (70 kDa heat shock protein) is preferentially induced by heat or stress stimuli. We previously found that Hsp70 is constitutively expressed in A6 mouse mesoangioblast stem cells, but its possible role in these cells and the control of its basal transcription remained unexplored. Here we report that in the absence of stress, Ku factor is able to bind the HSE (heat shock element) consensus sequence in vitro, and in vivo it is bound to the proximal hsp70 promoter. In addition, we show that constitutive hsp70 transcription depends on the co-operative interaction of different factors such as Sp1 (specificity protein 1) and GAGA-binding protein with Ku factor, which binds the HSE consensus sequence. We used mRNA interference assays to select knockdown cell clones. These cells were able to respond to heat stress by producing a large amount of Hsp70, and produced the same amount of Hsp70 as that synthesized by stressed A6 cells. However, severe Hsp70 knockdown cells had a longer duplication time, suggesting that constitutive Hsp70 expression has an effect on the rate of proliferation.

RNA polymerase II interacts with the Hspa1b promoter in mouse epididymal spermatozoa

The Hspa1b (Hsp70.1) gene is one of the first genes expressed after fertilization, with expression occurring during the minor zygotic genome activation (ZGA) in the absence of stress. This expression can take place in the male pronucleus as early as the one-cell stage of embryogenesis. The importance of HSPA1B for embryonic viability during times of stress is supported by studies showing that depletion of this protein results in a significant reduction in embryos developing to the blastocyte stage. Recently, we have begun addressing the mechanism responsible for allowing expression of Hspa1b during the minor ZGA and found that heat shock transcription factor (HSF) 1 and 2 bind the Hspa1b promoter during late spermatogenesis. In this report, we have extended those studies using western blots and chromatin immunoprecipitation assays and found that RNA polymerase II (Pol II) is present in epididymal spermatozoa and bound to the Hspa1b promoter. These present results, in addition to our previous results, support a model in which the binding of HSF1, HSF2, SP1, and Pol II to the promoter of Hspa1b would allow the rapid formation of a transcription-competent state during the minor ZGA, thereby allowing Hspa1b expression.

To be or not to be—Determinants of embryonic survival following heat shock

Elevated temperature can reduce developmental competence of the preimplantation embryo. Whether an embryo survives elevated temperature depends on its genotype, stage of development, exposure to regulatory molecules and redox status. Following fertilization, the embryo is very sensitive to heat shock. By Days 4-5 after insemination, however, the embryo has acquired increased resistance to elevated temperature. One system that may potentiate embryonic survival at later stages of embryonic development is the apoptosis response-inhibition of apoptosis responses at Day 4 exacerbated effects of heat shock on development. Embryo responses to heat shock at Days 4-5 also depend upon genotype because Bos indicus embryos are more resistant than embryos from non-adapted B. taurus. Some experiments (although not all) indicate that survival following heat shock can be increased by reducing oxygen tension, suggesting involvement of reactive oxygen species or hypoxia-induced factors. Embryonic responses to heat shock are also affected by regulatory molecules that act to modify cellular physiology and improve cell survival. The best characterized of these is insulin-like growth factor-1 (IGF-1). Actions of IGF-1 to allow development following heat shock are independent of its anti-apoptotic actions because inhibition of the phosphatidylinositol-3 kinase pathway through which IGF-1 blocks apoptosis does not prevent thermoprotective effects of IGF-1 on development. Identification of specific determinants of embryonic survival creates the opportunity for new strategies to improve pregnancy rates in animals exposed to heat stress. Many environmental perturbations activate similar cellular responses. Therefore, molecular and cellular systems that improve embryonic survival to heat shock may confer protection from other embryotoxic conditions.

Active caspase-3 and ultrastructural evidence of apoptosis in spontaneous and induced cell death in bovine in vitro produced pre-implantation embryos

In this study we investigated chronological onset and involvement of active caspase-3, apoptotic nuclear morphology, and TUNEL-labeling, as well as ultrastructural evidence of apoptosis, in both spontaneous and induced cell death during pre-implantation development of bovine in vitro produced embryos. Pre-implantation embryos (2-cell to Day 8 blastocysts) were cultured with either no supplementation (untreated) or with 10 microM staurosporine for 24 hr (treated). Embryos were subjected to immunohistochemical staining of active caspase-3, TUNEL-reaction for detection of DNA degradation and DAPI staining for detection of apoptotic nuclear morphology, and subjected to fluorescence microscopy. Additionally, treated and untreated blastocysts were fixed and processed for ultrastructural identification of apoptosis. Untreated embryos revealed no apoptotic features at 2- and 4-cell stages. However, active caspase-3 and apoptotic nuclear morphology were observed in an untreated 8-cell stage, and TUNEL-labeling was observed from the 16-cell stage. Blastomeres concurrently displaying all apoptotic features were present in a few embryos at 16-cell and morula stages and in all blastocysts. All three features were observed from the 8-cell stage in treated embryos, and blastomeres with apoptotic features appeared more numerous in treated than in untreated embryos. Ultrastructural evidence of apoptosis occurred with a comparable distribution pattern as apoptotic features detected by fluorescence microscopy in both treated and untreated blastocysts. Activation of caspase-3 is likely involved in both spontaneous and induced apoptosis in bovine pre-implantation embryos, and immunohistochemical staining of active caspase-3 may be used in combination with other markers to identify apoptosis in pre-implantation embryos.

Heat-shock proteins modulate the incidence of apoptosis and oxidative stress in preimplantation mouse embryos

We investigated the effect of antibodies to heat-shock proteins 60 and 70 on development, reactive oxygen species production, and incidence of apoptosis in preimplantation mouse embryos. Supplementation of culture media with antibodies to heat-shock proteins 60 and 70 resulted in significantly lower blastocyst development, hatching rate, reduced total cell number, and trophectoderm cell number, and increased the incidence of apoptosis in blastocysts compared to the control group.

Deletion of the inducible 70-kDa heat shock protein genes in mice impairs cardiac contractile function and calcium handling associated with hypertrophy

BACKGROUND

Hspa1a and Hspa1b genes encode stress-inducible 70-kDa heat shock proteins (Hsp70) that protect cells from insults such as ischemia. Mice with null mutations of both genes (KO) were generated, and their cardiac phenotype was explored.

METHODS AND RESULTS

Heart rate and blood pressures were normal in the KO mice. Hearts from KO mice were more susceptible to both functional and cellular damage by ischemia/reperfusion. Cardiac hypertrophy developed in Hsp70-KO mice. Ca2+ transients in cardiomyocytes of KO mice showed a delayed (120%) calcium decline and decreased sarcoplasmic reticulum calcium content. Cell shortening was decreased by 35%, and rates of contraction and relaxation were slower by 40%. These alterations can be attributed to the absence of Hsp70 because viral expression of Hsp70 in KO cultured cardiomyocytes restored these parameters. One mechanism underlying myocyte dysfunction could be decreased SERCA2a expression. This hypothesis was supported by a prolonged calcium decline and decreased SERCA2a protein. Viral SERCA2a expression restored contractility and Ca2+ transients. We examined the involvement of Jun N-terminal kinase (JNK), p38-mitogen-activated protein kinase (p38-MAPK), Raf-1, and extracellular signal-regulated kinase (ERK) in SERCA2a downregulation and the cardiac phenotype of KO mice. Levels of phosphorylated JNK, p38-MAPK, Raf-1, and ERK were elevated in KO hearts. Activation of the Raf-1-ERK pathway in normal cardiomyocytes resulted in decreased SERCA2a.

CONCLUSIONS

Absence of Hsp70 leads to dysfunctional cardiomyocytes and impaired stress response of Hsp70-KO hearts against ischemia/reperfusion. In addition, deletion of Hsp70 genes might induce cardiac dysfunction and development of cardiac hypertrophy through the activation of JNK, p38-MAPK, Raf-1, and ERK.

Mytilus trossulus hsp70 as a biomarker for arsenic exposure in the marine environment: laboratory and real-world results

The highly conserved heat shock protein 70 (hsp70) is induced by heat and chemical toxins, particularly heavy metals such as arsenic (As). The use of Mytilus trossulus (bay mussel) hsp70 as a 'screening' biomarker for marine heavy metals contamination was assessed. Some studies have found high hsp70 sensitivity to heavy metals, while others have found the opposite. Few studies have realistically used low heavy metals exposures, and fewer have used real-world contamination exposures. Clean sub-tidal mussels from the Puget Sound, Washington State (WA), USA, were acclimatized for 2 weeks and exposed for 24 h to As-spiked seawater (n=9) or to contaminated seawater from an arsenical pesticide plant in Tacoma, WA (n=10) followed by a Western blot for hsp70. Hsp70 inductions were insignificant at 10 microg l(-1) As(III), but were strong at 100 microg l(-1) (p<0.05) and 1000 microg l(-1) (p<0.01), with the induction threshold estimated at 30-50 microg l(-1) As(III). Hsp70 induction roughly correlated with arsenical toxicity, with As(III) > As(V) > (CH(3))(2)As(V). Altogether, the inter-individual variability of hsp70 levels tends to mask inductions at low As concentrations, making it a crude toxicity biomarker. In addressing this problem, the following options could prove promising: (1) pre- or post-stressing specimens for greater hsp70 sensitivity, (2) use of internal protein controls such as actin, (3) use of hsp70-reporter gene constructs, and (4) detection with hsp60, heme oxygenase-1, metallothionein, CYP450, MXR or GPx.

Stress response in mesoangioblast stem cells

Stem cells are presumed to survive various stresses, since they are recruited to areas of tissue damage and regeneration, where inflammatory cytokines and cytotoxic cells may result in severe cell injury. We explored the ability of mesoangioblasts to respond to different cell stresses such as heat, heavy metals and osmotic stress, by analyzing heat shock protein (HSP)70 synthesis as a stress indicator. We found that the A6 mesoangioblast stem cells constitutively synthesize HSP70 in a heat shock transcription factor (HSF)-independent way. However, A6 respond to heat shock and cadmium treatment by synthesizing HSP70 over the constitutive expression and this synthesis is HSF1 dependent. The exposure of A6 to copper or to a hypertonic medium does neither induce HSP70 synthesis nor activation of HSF1, while a constitutive binding of constitutive heat shock element binding factor was found. Together, these data suggest that mesoangioblasts constitutively express HSP70 as an 'a priori' activation mechanism, while they maintain the ability to respond to stress stimuli.

Spontaneous activation of pancreas trypsinogen in heat shock protein 70.1 knock-out mice

OBJECTIVES

Heat shock proteins (Hsp's) protect cellular proteins in response to injury, and the role of Hsp70 in experimental pancreatitis was recently described. To find out the possible role of Hsp70 in pancreatitis, we used Hsp70 knock-out mice (Hsp70.1-/-) and wild-type mice (Hsp70.1+/+).

METHODS

We studied enzymes activities, Hsp70 protein levels, and histologies in cerulein-induced pancreatitis of Hsp70.1-/- and Hsp70.1+/+ mice.

RESULTS

In the basal state, Hsp70 protein levels were higher in Hsp70.1+/+ than in Hsp70.1-/- mice, and trypsin activity was higher in Hsp70.1-/- than in Hsp70.1+/+ mice. The zymogen/lysosome ratio of cathepsin B activity before cerulein injection was higher in Hsp70.1-/- than in Hsp70.1+/+ mice. The expression level of Hsp70 in the pancreas increased in both of Hsp70.1-/- and Hsp70.1+/+ mice after hyperthermia because of the Hsp70.3 gene left intact in Hsp70.1-/- mice. After cerulein hyperstimulation, trypsin activity increased 2-fold in Hsp70.1+/+ mice, but cerulein did not further increase basally elevated trypsin activity in Hsp70.1-/- mice. Hyperthermia pretreatment not only blocked cerulein-induced trypsinogen activation, pancreatic edema, and vacuolization in Hsp70.1+/+ mice, but also decreased basally elevated trypsin activity in Hsp70.1-/- mice.

CONCLUSIONS

Hsp70 can be responsible for inhibition of cerulein-induced pancreatitis and prevention of spontaneous trypsinogen activation in mice by inhibiting the colocalization of zymogen and lysosomal enzymes.

RNA in human sperm

We have yet to develop a fundamental understanding of the molecular complexities of human spermatozoa. This encompasses the unique packaging and structure of the sperm genome along with their paternally derived RNAs in preparation for their delivery to the egg. The diversity of these transcripts is vast, including several anti-sense molecules resembling known regulatory micro-RNAs. The field is still grasping with its delivery to the oocyte at fertilization and possible significance. It remains tempting to analogize them to maternally-derived transcripts active in early embryo patterning. Irrespective of their role in the embryo, their use as a means to assess male factor infertility is promising.

Protective Effect ofHeat Shock Proteins 70.1and70.3on Retinal Photic Injury after Systemic Hyperthermia

PURPOSE

This study aimed to determine the relationship between the heat shock protein 70 from hsps70.1 and 70.3 on retinal photic injury after systemic hyperthermia.

METHODS

Eight-week-old female C57BU6 mice were kept at a constant temperature of 41-42 degrees C for 25-30 minutes. After dark-adaptation for 8 hours, intense light of 11000 lux was maintained for 6 hours. Histology and immunohistochemistry for the inducible heat shock protein 70 (hsp70), the constitutive heat shock protein 70 (hsc70), and westem blot analysis, reverse transcriptase-polymerase chain reaction for hsp70.1 and hsp70.3 were performed just before photic injury and after 1, 4, 7, and 14 days.

RESULTS

Light-induced retinal degeneration was prevented by thermotolerance. After hyperthermia, hsp70 was densely expressed in the inner segment of the photoreceptor layer on the photic injury. Hsp70 expression increased for 4 days after photic injury and slowly decreased thereafter. mRNA from hsp70.3 was induced earlier than that of hsp70.1.

CONCLUSIONS

Retinal photic injury was prevented by hyperthermia-induced hsp70. Hsp70 from hsp70.3 may be a rapid and short-lived responder, and that from hsp70.1 is a slower and more sustained responder. Hsp70 from hsp70.3 may be an initial retinal chaperone while hsp70 from hsp70.1 may be a sustained chaperone.

Granzyme N, a Novel Granzyme, Is Expressed in Spermatocytes and Spermatids of the Mouse Testis1

We cloned a cDNA for a novel granzyme, granzyme N (Gzmn), from a mouse testes cDNA library. The testes contained two distinct species of Gzmn mRNA, one of which codes for a complete protein of 248 amino acids with three essential residues required for catalytic activity. The Gzmn mRNA was specifically expressed in the testes of adult mice. The Gzmn expression was found to initiate in the testes at 3 wk of age and to become more prominent as the animal reached sexual maturity. In situ hybridization analysis revealed that both spermatocytes and spermatids of the adult mouse testes express Gzmn mRNA. Consistent with these findings, the protein was immunohistochemically detected in the spermatocytes and spermatids, although some of the germ cells showed no positive staining. Gzmn was demonstrated to be a secretory and N-glycosylated protein that exists in two protein forms in the testes extract. In the cryptorchid testes, the expression of Gzmn transcript was drastically reduced on Postoperative Day 10, whereas the protein level was gradually decreased starting on Day 6. The local heating (43 degrees C, 20 min) of the testes did not change the Gzmn expression level at either 8 or 16 h after treatment. These results suggest that Gzmn is not involved in the process of germ cell apoptosis induced by heat shock, but that it may be involved in spermatogenesis in the mouse testes.

Early transcriptional activation of the hsp70.1 gene by osmotic stress in one-cell embryos of the mouse

In fertilized mouse eggs, de novo transcription of embryonic genes is first observed during the S phase of the one-cell stage. This transcription, however, is mostly limited to the male pronucleus and possibly uncoupled from translation, making the functional meaning obscure. We found that one-cell mouse embryos respond to the osmotic shock of in vitro isolation with migration of HSF1, the canonical stress activator of mammalian heat shock genes, to pronuclei and by transient transcription of the hsp70.1, but not hsp70.3 and hsp90, heat shock genes. Isolated growing dictyate oocytes also display a nuclear HSF1 localization, but, in contrast with embryos, they transcribe both hsp70.1 and hsp70.3 genes only after heat shock. Intranuclear injection of double-stranded oligodeoxyribonucleotides containing HSE, GAGA box or GC box consensus sequences, and antibodies raised to transcription factors HSF1, HSF2, Drosophila melanogaster GAGA factor, or Sp1 demonstrated that hsp70.1 transcription depends on HSF1 in both oocytes and embryos and that Sp1 is dispensable in oocytes and inhibitory in the embryos. Hsp70.1 thus represents the first endogenous gene so far identified to be physiologically activated and tightly regulated after fertilization in mammals.

Mercury, cadmium, and arsenite enhance heat shock protein synthesis in chick embryos prior to embryotoxicity

BACKGROUND

Cells respond to adverse environmental stimuli by enhancing the expression of specific genes, the products of which include a suite of proteins known as heat shock proteins (hsps), a response often attributed to cellular protection.

METHODS

In this study, we characterized alterations in hsp expression in chick embryos (Hamburger-Hamilton stage 17, 72 h) exposed in ovo to arsenite (As), mercury (Hg), and cadmium (Cd), known developmental toxicants. Embryos were incubated for 2 h following exposure to 3, 10, 30, or 100 nmol metal, or for 2, 4, 12, or 24 h following treatment with 10 nmol metal.

RESULTS

An enhanced de novo synthesis of 24-, 70-, and 90-kD, 70- and 90-kD, and 70-kD proteins was observed with As, Hg, and Cd treatments, respectively. These responses were transient; apparent rates of protein synthesis were maximal 2-4 h after exposure and returned to control rates by 24 h. Actinomycin D experiments demonstrated that arsenite-induced expression of these proteins is transcriptionally regulated. Immunoblotting experiments identified the 24-, 70-, and 90-kD proteins as the heat shock proteins hsp24, hsp70, and hsp90, respectively. Exposure duration-related abnormalities were noted in the neural tube with all metals and in the ganglia and somites with Cd and As. Retina, allantois, and limb defects were specific to Cd-treated embryos, and branchial arch defects were specific to As-treated embryos.

CONCLUSIONS

The data support metal-induced developmental abnormalities, which are preceded by synthesis of stress proteins.

Heat shock proteins in mammalian development

Mammalian development follows a defined but adjustable program, depending on the plasticity of embryonic cells 'response to environmental changes. Heat shock proteins (Hsp) are integral part of this developmental program and gene targeting experiments have started to unravel developmental processes, which exhibit specific requirements for Hsps (e.g. Hsp70.2 for spermatogenesis). In the present paper, we will review available data on Hsp function and discuss the roles of heat shock factors (HSF), their major regulators, in mammalian development.

HSP70.1 and -70.3 are required for late-phase protection induced by ischemic preconditioning of mouse hearts

We investigated the role of inducible heat shock proteins 70.1 and 70.3 (HSP70.1 and HSP70.3, respectively) in myocardial ischemic preconditioning (IP) in mice. Wild-type (WT) mice and HSP70.1- and HSP70.3-null [HSP70.1/3(-/-)] mice were subjected to IP and examined 24 h later during the late phase of protection. IP significantly increased steady-state levels of HSP70.1 and HSP70.3 mRNA and expression of inducible HSP70 protein in WT myocardium. To assess protection against tissue injury, mice were subjected to 30 min of regional ischemia and 3 h of reperfusion. In WT mice, IP reduced infarct size by 43% compared with sham IP-treated mice. In contrast, IP did not reduce infarct size in HSP70.1/3(-/-) mice. Absence of inducible HSP70.1 and HSP70.3 had no effect, however, on classical or early-phase protection produced by IP, which significantly reduced infarct size in HSP70.1/3(-/-) mice. We conclude that inducible HSP70.1 and HSP70.3 are required for late-phase protection against infarction following IP in mice.

Thoughts on embryo culture conditions

This review discusses three topics: (i) the 'back to nature' and empirical optimization approaches to the design of chemically defined media for the culture of preimplantation embryos, (ii) the evolution of the simplex optimized family of media, and (iii) adaptation and stress in preimplantation embryos when placed in chemically defined media.

Developmental changes in inhibitory effects of arsenic and heat shock on growth of pre-implantation bovine embryos

Although sensitive to various disrupters, pre-implantation embryos possess some cellular cytoprotective mechanisms that allow continued survival in the face of a deleterious environment. For stresses such as heat shock, embryonic resistance increases as development proceeds. Present objectives were to determine whether (1) arsenic compromises development of pre-implantation bovine embryos, (2) developmental changes in embryonic resistance to arsenic mimic those seen for resistance to heat shock, and (3) developmental patterns in induction of apoptosis by arsenic are correlated with similar changes in resistance of embryos to inhibitory effects of arsenic on development. Bovine embryos produced by in vitro fertilization were exposed at the two-cell stage or at day 5 after insemination (embryos > or = 16-cells in number) to either sodium arsenite (0, 1, 5, or 10 microM) or heat shock (exposure to 41 degrees C for 0, 3, 4.5, 6, or 9 hr). Arsenic induced apoptosis and increased group 2 caspase activity for embryos at the > or = 16-cell stage, but not for embryos at the two-cell stage. In contrast to these developmental changes in apoptosis responses, exposure to arsenic reduced cell number 24 hr after exposure for both two-cell embryos and embryos > or = 16-cells. Similarly, the percentage of embryos that developed to the blastocyst stage at day 8 after fertilization was reduced by arsenic exposure at both stages of development. Heat shock, conversely, reduced development to the blastocyst stage when applied at the two-cell stage, but not when applied to embryos > or = 16-cells at day 5 after insemination. In conclusion, arsenic can compromise development of bovine pre-implantation embryos, the temporal window of sensitivity of embryos to arsenic is wider than for heat shock, and cellular cytoprotective responses that embryos acquire for thermal resistance are not sufficient to cause increased embryonic resistance to arsenic exposure. It is likely that despite common cellular pathologies caused by arsenic and heat shock, arsenic acts to reduce development in part through biochemical pathways not activated by heat shock. Moreover, the embryo does not acquire significant resistance to these perturbations within the time frame in development examined.

Glucose transporter 8 expression and translocation are critical for murine blastocyst survival

Glucose transporter (GLUT) 8 is an insulin-responsive facilitative glucose transporter expressed predominantly in the murine blastocyst. To determine the physiologic role of GLUT8, two-cell embryos were cultured to a blastocyst stage in antisense or sense oligonucleotides to GLUT8. Apoptosis was assessed using the TUNEL techniques and recorded as the percentage of TUNEL-positive nuclei/total nuclei. Embryos cultured in GLUT8 antisense experienced increased TUNEL-positive nuclei, whereas sense embryos did not. Embryos cultured in a control AS oligonucleotide, specific for heat shock protein 70-2, showed a rate of apoptosis similar to sense. To determine the outcome of these apoptotic embryos, blastocysts exposed to sense vs. antisense were transferred back into foster mice and the pregnancy continued until Day 14.5, at which time the uteri were examined for normal gestational sacs and resorptions. Embryos exposed to GLUT8 antisense experienced higher rates of resorptions and lower normal pregnancy rates compared to embryos cultured in GLUT8 sense. To examine the insulin growth factor (IGF)-1/insulin intracellular signaling pathways involved in GLUT8 translocation, IGF-1 receptor (IGF-1R) expression was decreased in the blastocysts with antisense oligonucleotides. Using confocal immunofluorescent microscopy, GLUT8 translocation in response to insulin was observed. Exposure to insulin in the embryos exposed to IGF-1R sense induced translocation of GLUT8 from intracellular compartments to the plasma membrane. Blastocysts exposed to IGF-1R antisense, however, failed to demonstrate any change in the intracellular location of GLUT8 with insulin treatment. The IGF-1R antisense embryos also displayed significantly greater TUNEL staining compared to sense embryos. These data suggest that GLUT8 expression and translocation in response to insulin are critical for blastocyst survival.

Induced thermotolerance in bovine two-cell embryos and the role of heat shock protein 70 in embryonic development

Induced thermotolerance is a phenomenon whereby exposure to a mild heat shock can induce heat shock proteins (HSP) and other cellular changes to make cells more resistant to a subsequent, more severe heat shock. Given that the 2-cell bovine embryo is very sensitive to heat shock, but can also produce HSP70 in response to elevated temperature, experiments were conducted to test whether 2-cell embryos could be made to undergo induced thermotolerance. Another objective was to test the role of the heat-inducible form of heat shock protein 70 (HSP70i) in development and sensitivity of bovine embryos to heat shock. To test for induced thermotolerance, 2-cell bovine embryos were first exposed to a mild heat shock (40 degrees C for 1 hr, or 41 degrees C or 42 degrees C for 80 min), allowed to recover at 38.5 degrees C and 5% (v/v) CO2 for 2 hr, and then exposed to a severe heat shock (41 degrees C for 4.5, 6, or 12 hr). Regardless of the conditions, previous exposure to mild heat shock did not reduce the deleterious effect of heat shock on development of embryos to the blastocyst stage. The role of HSP70i in embryonic development was tested in two experiments by culturing embryos with a monoclonal antibody to the inducible form of HSP70. At both 38.5 degrees C and 41 degrees C, the proportion of 2-cell embryos that developed to blastocyst was reduced (P < 0.05) by addition of anti-HSP70i to the culture medium. In contrast, sensitivity to heat shock was not generally increased by addition of antibody. In conclusion, bovine 2-cell embryos appear incapable of induced thermotolerance. Lack of capacity for induced thermotolerance could explain in part the increased sensitivity of 2-cell embryos to heat shock as compared to embryos at later stages of development. Results also implicate a role for HSP70i in normal development of bovine embryos.

Programmed cell death in the neurulating embryo is prevented by the chaperone heat shock cognate 70

Neuronal cell death is a genuine developmental process, with precise regulation and defined roles. In striking contrast, characterization of cell death that occurs at early stages of neural development is very limited. We previously showed that embryonic proinsulin increases the level of the chaperone heat shock cognate 70 (Hsc70) and reduces the incidence of apoptosis in the neurulating chick embryo [de la Rosa, et al. (1998), Proc. Natl. Acad. Sci. USA, 95, 9950]. We now demonstrate that Hsc70 is directly involved in cell survival during neurulation, as specific downregulation of endogenous Hsc70 by antisense oligodeoxynucleotide interference provoked an increase in apoptosis both in vitro and in ovo. In parallel, activation of caspase-3 was increased after hsc70 antisense oligodeoxynucleotide treatment. Dead cells were located mostly in the developing nervous system, distributed in areas where the incidence of cell death was high. These areas coincided both in vivo and under different death-inducing conditions, including antisense interference and growth factor deprivation. Hsc70 immunostaining was strong in at least some areas of high cell death. Apoptotic cells within these areas presented undetectable Hsc70 levels, however, suggesting that this protein acts as an intrinsic protector of neuroepithelial and neural precursor cells.

Genetic regulation of preimplantation embryo survival

Mammalian embryonic death is the most common outcome of fertilization. This review focuses on the recent advances concerning genetic regulation of preimplantation embryo survival. The predominant role of the Ped(preimplantation embryo development) gene, which regulates fast or slow cleavage of preimplantation mouse embryos, and its implication on embryo survival are discussed. Recent morphological and biochemical observations suggested that programmed cell death was an essential mechanism in preimplantation embryo fragmentation and survival, thus leading to original investigations on apoptosis and apoptosis-related genes. Other genes, transcripts, or proteins seem to be involved in embryo development and control of survival. In particular, the role of heat shock proteins (HSP), telomerase activity (human telomerase catalytic subunit hTCS), and the developmental significance of regulatory protein polarization (leptin, STAT 3) in preimplantation embryos are discussed.

DNA topoisomerase II is essential for preimplantation mouse development

Topoisomerase II (topo II) is an essential enzyme that alters DNA topology. This activity is important for a variety of chromosome functions including DNA replication, transcription, recombination, and chromosome condensation and segregation. Previously we localized topo II in mouse gametes and preimplantation embryos using isoform-specific antibodies demonstrating the presence of the enzyme in oocytes and embryos, but not sperm. To probe functions of topo II during preimplantation development, we treated mouse zygotes with 100 nM teniposide, and assessed embryo morphology and DNA replication. Teniposide blocked cleavage in 69% embryos; the remainder cleaved once but had abnormal nuclei. Teniposide-treated embryos were devoid of topo II immunofluorescence. Teniposide also prevented DNA replication, implicating topo II in this process. Embryos treated with a 2 hr pulse of teniposide recovered and developed to the blastocyst stage, indicating 100 nM teniposide did not induce apoptosis. To more specifically analyze topo IIalpha function, we treated zygotes with topo IIalpha-targeted antisense oligodeoxynucleotides. Most zygotes arrested at the 2-cell stage while controls developed into blastocysts indicating topo IIalpha is essential for preimplantation development. The absence of topo IIalpha, but not beta immunofluorescence in antisense-treated embryos confirms the specificity and impact of the treatment. In addition, topo IIalpha is newly synthesized at the 2-cell stage. These results establish an essential function for topo II in mouse preimplantation embryonic development.

Effects of heat shock protein 70 (Hsp70) on arsenite-induced genotoxicity

Arsenic, a human carcinogen, is genotoxic, although its mechanism(s) of action for tumorigenesis is not well understood. Among the toxicity-related properties of this chemical are its clastogenic and aneugenic activities, as well as its capacity for inducing stress-response in the form of elevated heat shock protein (HSP) expression. In the present study, we evaluated the effects of Hsp70 expression on arsenite (As)-induced structural and numerical chromosome anomalies in human cells. Human MCF-7 Tet-off cells stably transfected with a pTRE/Hsp70-1 transgene construct were used to regulate Hsp70 levels prior to in vitro As exposures. Separate cultures of relatively high vs. low Hsp70-expressing cells were established. A cytokinesis block micronucleus assay with kinetochore immunostaining was used to detect micronuclei (MN) derived from chromosome breakage (K-MN) or loss (K+MN). These studies demonstrated significant increases in micronucleus frequencies in response to As following either a long exposure (5 or 10 microM for 46 hr), or short exposure (10 or 40 microM for 8 hr) protocol. Overall, the long protocol was more efficient in producing K+MN and cells with multiple MN. Overexpressing Hsp70 resulted in significant reductions in the percent of cells positive for MN for both the long and short As exposure protocols. Both K+ and K- types of As-induced MN were lower in cells with elevated Hsp70 as compared to cells without overexpression of Hsp70. We conclude that the dose and duration of As exposure influence the type as well as amount of chromosomal alteration produced and that inducible Hsp70 protects against both the clastogenic and aneugenic effects of this chemical.

Stress proteins induced by arsenic

The elevated expression of stress proteins is considered to be a universal response to adverse conditions, representing a potential mechanism of cellular defense against disease and a potential target for novel therapeutics. Exposure to arsenicals either in vitro or in vivo in a variety of model systems has been shown to cause the induction of a number of the major stress protein families such as heat shock proteins (Hsp). Among them are members with low molecular weight, such as metallotionein and ubiquitin, as well as ones with masses of 27, 32, 60, 70, 90, and 110 kDa. In most of the cases, the induction of stress proteins depends on the capacity of the arsenical to reach the target, its valence, and the type of exposure, arsenite being the biggest inducer of most Hsp in several organs and systems. Hsp induction is a rapid dose-dependent response (1-8 h) to the acute exposure to arsenite. Thus, the stress response appears to be useful to monitor the sublethal toxicity resulting from a single exposure to arsenite. The present paper offers a critical review of the capacity of arsenicals to modulate the expression and/or accumulation of stress proteins. The physiological consequences of the arsenic-induced stress and its usefulness in monitoring effects resulting from arsenic exposure in humans and other organisms are discussed.

Heat shock proteins Hsp70-1 and Hsp70-3 Are necessary and sufficient to prevent arsenite-induced dysmorphology in mouse embryos

Heat Shock Proteins (HSPs) represent a variety of protein families that are induced by stressors such as heat and toxicants, and the induction of HSPs in the organogenesis stage rodent embryo is well established. It has been proposed that thermotolerance and chemotolerance result from expression of the HSPs. However, whether these proteins function to prevent dysmorphogenesis and which family members serve this function are unknown. Therefore, we evaluated the specific ability of stress-inducible Hsp70-1 and Hsp70-3 to prevent arsenite-induced dysmorphology in the cultured mouse embryo using gain- and loss-of-function models. Loss of HSP function was accomplished by injecting antisense oligonucleotides directed against hsp70-1 and hsp 70-3 mRNAs into the amniotic cavity of cultured Day 9 mouse embryos. Suppression of hsp70-1 and hsp70-3 expression resulted in an up to six-fold increase in the incidence of arsenite-induced neural tube defects. Gain of HSP function was accomplished by microinjecting a transgene with a constitutive promotor driving expression of the hsp70-1 coding region, and resulted in a decreased incidence of arsenite-induced neural tube defects. These results indicate that Hsp70-1 and Hsp70-3 are both necessary and sufficient for preventing arsenite-induced dysmorphology in early-somite staged mouse embryos. Mol. Reprod. Dev. 59:285-293, 2001.

Effects of hyperthermia on spermatogenesis, apoptosis, gene expression, and fertility in adult male mice

Testicular heat shock was used to characterize cellular and molecular mechanisms involved in male fertility. This model is relevant because heat shock proteins (HSPs) are required for spermatogenesis and also protect cells from environmental hazards such as heat, radiation, and chemicals. Cellular and molecular methods were used to characterize effects of testicular heat shock (43 degrees C for 20 min) at different times posttreatment. Mating studies confirmed conclusions, based on histopathology, that spermatocytes are the most susceptible cell type. Apoptosis in spermatocytes was confirmed by TUNEL, and was temporally correlated with the expression of stress-inducible Hsp70-1 and Hsp70-3 proteins in spermatocytes. To further characterize gene expression networks associated with heat shock-induced effects, we used DNA microarrays to interrogate the expression of 2208 genes and thousands more expression sequence tags expressed in mouse testis. Of these genes, 27 were up-regulated and 151 were down-regulated after heat shock. Array data were concordant with the disruption of meiotic spermatogenesis, the heat-induced expression of HSPs, and an increase in apoptotic spermatocytes. Furthermore, array data indicated increased expression of four additional non-HSP stress response genes, and eight cell-adhesion, signaling, and signal-transduction genes. Decreased expression was recorded for 10 DNA repair and recombination genes; 9 protein synthesis, folding, and targeting genes; 9 cell cycle genes; 5 apoptosis genes; and 4 glutathione metabolism genes. Thus, the array data identify numerous candidate genes for further analysis in the heat-shocked testis model, and suggest multiple possible mechanisms for heat shock-induced infertility.

Development of a 950-gene DNA array for examining gene expression patterns in mouse testis

BACKGROUND

Over the past five years, interest in and use of DNA array technology has increased dramatically, and there has been a surge in demand for different types of arrays. Although manufacturers offer a number of pre-made arrays, these are generally of utilitarian design and often cannot accommodate the specific requirements of focused research, such as a particular set of genes from a particular tissue. We found that suppliers did not provide an array to suit our particular interest in testicular toxicology, and therefore elected to design and produce our own.

RESULTS

We describe the procedures used by members of the US Environmental Protection Agency MicroArray Consortium (EPAMAC) to produce a mouse testis expression array on both filter and glass-slide formats. The approaches used in the selection and assembly of a pertinent, nonredundant list of testis-expressed genes are detailed. Hybridization of the filter arrays with normal and bromochloroacetic acid-treated mouse testicular RNAs demonstrated that all the selected genes on the array were expressed in mouse testes.

CONCLUSION

We have assembled two lists of mouse (950) and human (960) genes expressed in the mouse and/or human adult testis, essentially all of which are available as sequence-verified clones from public sources. Of these, 764 are homologous and will therefore enable close comparison of gene expression between murine models and human clinical testicular samples.

Subcellular localization of presenilins during mouse preimplantation development

The genes defective in familial Alzheimer's disease encode the proteins presenilin 1 and 2 (PS1 and 2). Expression of presenilins (PSs) and their proteolytic processing are regulated during neuronal development. Even though these proteins are detected and regulated mainly in Golgi and endoplasmic reticulum, their subcellular distribution during the development is not known. The present study aimed to investigate the localization of PSs and their role during early developmental stage using mouse embryo model. At preimplantation stage, PSs were detected not only in cytoplasm, but also in the nucleus from oocyte to 2.5 dpc (day postcoitum), then disappeared in the nucleus at blastocyst stage (3.5 dpc). Antisense against PS1 and PS2 decreased the transition to blastocyst stage, whereas each antisense alone had no effect. Treatment with lactacystin (26S proteosome inhibitor), which arrest cell cycle at M phase, redistributed PSs into centrosome-kinetochore microtubule. PS2 overexpression in HEK 293 cell arrested cell cycle at S phase. These data suggest that PSs play key roles in cell division and differentiation during early development.