CRISPR/Cas9-induced vitellogenin knockout lead to incomplete embryonic development in Plutella xylostella

Vitellogenin (Vg) is important for insect egg maturation and embryo development. In the present study, we characterized the molecular structure and expression profile of Vg gene, and analyzed its reproductive functions in diamondback moth, Plutella xylostella (L.), a destructive pest of cruciferous crops, using CRISPR/Cas9 system. The P. xylostella Vg (PxVg) included all conserved domains and motifs that were commonly found in most insect Vgs except for the polyserine tract. PxVg gene was highly expressed in female pupae and adults. PxVg protein was detected in eggs and female adults. PxVg was mainly expressed in the fat body and its protein was detected in most tissues, except in the midgut. CRISPR/Cas9-induced PxVg knockout successfully constructed a homozygous mutant strain with a 5-base pair nucleotide deletion. No PxVg protein was found in the mutant individuals and in their ovaries. There were no significant differences between wild (WT) and mutant (Mut-5) types of P. xylostella in terms of ovariole length and the number of fully developed oocytes in newly emerged females. No significant difference was observed in the number of eggs laid within two days, but there was a lower egg hatchability (84% for WT vs. 47% for Mut-5). This is the first study presenting the functions of Vg in ovary development, egg maturation, oviposition and embryonic development of P. xylostella. Our results suggest that the reproductive functions of Vg may be species-specific in insects. It is possible that Vg may not be the major egg yolk protein precursor in P. xylostella. Other "functional Vgs" closely involved in the yolk formation and oogenesis would need to be further explored in P. xylostella.

CRISPR/Cas9-Mediated Vitellogenin Receptor Knockout Leads to Functional Deficiency in the Reproductive Development of Plutella xylostella

The vitellogenin receptor (VgR) belongs to the low-density lipoprotein receptor (LDLR) gene superfamily and plays an indispensable role in Vg transport, yolk deposition, and oocyte development. For this reason, it has become a promising target for pest control. The involvement of VgR in Vg transport and reproductive functions remains unclear in diamondback moths, Plutella xylostella (L.), a destructive pest of cruciferous crops. Here, we cloned and identified the complete cDNA sequence of P. xylostella VgR, which encoded 1805 amino acid residues and contained four conserved domains of LDLR superfamily. PxVgR was mainly expressed in female adults, more specifically in the ovary. PxVgR protein also showed the similar expression profile with the PxVgR transcript. CRISPR/Cas9-mediated PxVgR knockout created a homozygous mutant of P. xylostella with 5-bp-nucleotide deletion in the PxVgR. The expression deficiency of PxVgR protein was detected in the ovaries and eggs of mutant individuals. Vg protein was still detected in the eggs of the mutant individuals, but with a decreased expression level. However, PxVg transcripts were not significantly affected by the PxVgR knockout. Knockout of PxVgR resulted in shorter ovarioles of newly emerged females. No significant difference was detected between wild and mutant individuals in terms of the number of eggs laid in the first 3 days after mating. The loss of PxVgR gene resulted in smaller and whiter eggs and lower egg hatching rate. This study represents the first report on the functions of VgR in Vg transport, ovary development, oviposition, and embryonic development of P. xylostella using CRISPR/Cas9 technology. This study lays the foundation for understanding molecular mechanisms of P. xylostella reproduction, and for making use of VgR as a potential genetic-based molecular target for better control of the P. xylostella.

Identification of Halloween Genes and RNA Interference-Mediated Functional Characterization of a Halloween Gene shadow in Plutella xylostella

Ecdysteroids play an essential role in controlling insect development and reproduction. Their pathway is regulated by a group of enzymes called Halloween gene proteins. The relationship between the Halloween genes and ecdysteroid synthesis has yet to be clearly understood in diamondback moth, Plutella xylostella (L.), a worldwide Lepidoptera pest attacking cruciferous crops and wild plants. In this study, complete sequences for six Halloween genes, neverland (nvd), shroud (sro), spook (spo), phantom (phm), disembodied (dib), shadow (sad), and shade (shd), were identified. Phylogenetic analysis revealed a strong conservation in insects, including Halloween genes of P. xylostella that was clustered with all other Lepidoptera species. Three Halloween genes, dib, sad, and shd were highly expressed in the adult stage, while nvd and spo were highly expressed in the egg and pupal stages, respectively. Five Halloween genes were highly expressed specifically in the prothorax, which is the major site of ecdysone production. However, shd was expressed predominantly in the fat body to convert ecdysone into 20-hydroxyecdysone. RNAi-based knockdown of sad, which is involved in the last step of ecdysone biosynthesis, significantly reduced the 20E titer and resulted in a longer developmental duration and lower pupation of fourth-instar larvae, as well as caused shorter ovarioles and fewer fully developed eggs of P. xylostella. Furthermore, after the knockdown of sad, the expression levels of Vg and VgR genes were significantly decreased by 77.1 and 53.0%. Meanwhile, the number of eggs laid after 3 days was significantly reduced in sad knockdown females. These results suggest that Halloween genes may play a critical role in the biosynthesis of ecdysteroids and be involved in the development and reproduction of P. xylostella. Our work provides a solid basis for understanding the functional importance of these genes, which will help to screening potential genes for pest management of P. xylostella.

Effects of 1-bromopropane, 2-bromopropane, and 1,2-dichloropropane on the estrous cycle and ovulation in F344 rats

The present study was performed to investigate comparatively the toxic effects of inhalation exposure of 1-bromopropane, 2-bromopropane, and 1,2-dichloropropane on reproductive physiology, particularly on the estrous cycle and spontaneous ovulation in female F344 rats. The rats received inhalation exposure to different halogenated propanes, and were exposed daily for 8 h throughout almost 3 weeks to 0,50,200 and 1000 ppm of 1-bromopropane or 2-bromopropane, or to 0,50,100 and 200 ppm of 1,2-dichloropropane. Throughout the exposure period of 1-bromopropane or 2-bromopropane, the ratio of the number of estrous cycle of 6 days or longer to the number of all cycles in both 1000 ppm groups were about two-fold the ratio in each control group, however, no significant difference was found between the ratios of exposed and control groups. The ratios of such long estrous cycles in groups exposed to 100 or 200 ppm of 1,2-dichloropropane were six- to seven-fold higher than that of the control group. These ratios in exposed rats differed significantly from those of controls. The number of ovulated ova in rats exposed to 1,2-dichloropropane decreased in a dose-dependent manner, and the number of ovulated ova in the 200 ppm group was significantly different from that of control rats. Such significant changes in ovulation were not observed in rats exposed to 1-bromopropane or 2-bromopropane. The absolute and relative weights of the ovaries and uterus in rats exposed to three halogenated propanes were not significantly different from those in each control. Therefore, the present study clarified that: (1) 1,2-dichloropropane prolonged the length of the estrous cycle and inhibited spontaneous ovulation in F344 rats; and (2) the potency of 1,2-dichloropropane to disturb the female reproductive physiology appeared to be greater compared with that of 1-bromopropane and 2-bromopropane under the present conditions of inhalation exposure.

Genetic alterations in microsatellite marker sites among tumor suppressor genes in endometriosis

Four endometriotic lesions were examined for the presence of genetic alterations in microsatellite marker sites among eight tumor suppressor genes. For this, a microdissection method was used on paraffin sections. Only one instance of loss of heterozygosity was detected at the PTCH locus. Heterozygosity was retained (indicating the absence of both loss of heterozygosity and microsatellite instability) at the other seven tumor suppressor gene loci in all the cases. Among the tumor suppressor genes examined, genetic defects in these microsatellite regions are certainly not ubiquitous in endometriosis and may be uncommon.

Demonstration of focal p53 expression without genetic alterations in endometriotic lesions

Their monoclonal origin (as indicated by recent investigations) indicates the neoplastic nature of most endometriotic lesions. p53, a representative tumor suppressor, regulates cell proliferation, and genetic alterations in p53 are involved in carcinogenesis in a wide variety of human cancers. The aim of this study was to examine endometriotic lesions for p53 expression and genetic alterations in p53. An immunohistochemical study revealed that 20% (13/64) of endometriotic lesions showed focal p53 expression in the epithelial cells. Using serial paraffin sections, we employed a microdissection method to extract DNA from the endometriotic tissues that showed p53 expression. No mutations were found in exons 5-8 in p53 by cleavase fragment length polymorphism scanning and polymerase chain reaction-DNA sequencing. Moreover, neither loss of heterozygosity nor microsatellite instability was detected at the microsatellite marker sites of p53. These results suggest that the focal p53 expression recognized in the endometriotic epithelia may be due to overproduction of wild-type p53 protein.

Frequent occurrence of loss of heterozygosity among tumor suppressor genes in uterine leiomyosarcoma

OBJECTIVE

Leiomyosarcoma of the uterus is a rare smooth muscle tumor; it is extremely malignant and the rates of local recurrence and metastasis are high. Since tumor suppressor genes are commonly altered in malignant tumors, it is possible that mutations in such genes are involved in the development of uterine leiomyosarcoma.

METHODS

Fifty-five patients (37-70 years of age) diagnosed as having smooth muscle tumors of the uterus were selected. DNA was extracted from four or five 8-microm-thick consecutive tissue sections of each smooth muscle tumor from the paraffin-embedded blocks. Loss of heterozygosity (LOH) was investigated at nine loci within or close to tumor suppressor genes (TP53, RB1, DCC, NM23, WT1, D14S267, P16, DPC4, PTCH).

RESULTS

Nineteen of twenty leiomyosarcomas revealed at least one instance of LOH among eight of the nine markers tested (one locus showed no LOH at all). In fact, 11 of the 20 cases exhibited two or more instances of LOH and, of the remaining 9 cases, 4 showed a point mutation of p53 in addition to an alteration in one of the 9 markers, while one exhibited a p53 mutation only.

CONCLUSION

An accumulation of genetic alterations among tumor suppressor genes may play a key role in the tumorigenesis and progression of uterine leiomyosarcoma.

Prognostic significance of bcl-2 expression in leiomyosarcoma of the uterus

We examined bcl-2 expression as well as p53 expression and mutation in human uterine smooth muscle tumours to determine the influence of bcl-2 expression on prognosis in patients with uterine leiomyosarcomas. bcl-2 protein was expressed in nearly all benign smooth muscle tumours but in only 57% of leiomyosarcomas. Benign smooth muscle tumours were usually negative for p53 protein, but 16 out of 21 (76%) leiomyosarcomas were positive. A p53 gene mutation was detected in nine of the 16 leiomyosarcomas that showed p53-positive staining. A significant positive correlation was observed between p53 mutation and p53 expression, between the number of mitoses and the Ki-67 labelling index, and between clinical stage and p53 mutation. A significant negative correlation was observed between bcl-2 expression and p53 mutation, and between bcl-2 expression and p53 overexpression. Univariate survival analysis revealed that bcl-2 expression, p53 mutation and clinical stage (stage 1 vs stages 2-4) all showed a significant correlation with prognosis. In a multivariate stepwise regression analysis, positive bcl-2 expression and stage 1 disease were the independent predictors of a favourable prognosis. Our results suggest that bcl-2 is frequently expressed in human uterine smooth muscle tumours, and that its expression may correlate with a favourable prognosis in patients with uterine leiomyosarcoma.

Infrequent occurrence of high-risk human papillomavirus and of p53 mutation in minimal deviation adenocarcinoma of the cervix

To assess the occurrence of high-risk human papillomavirus (HPV) infection and p53 alterations in minimal deviation adenocarcinoma (MDA) of the uterine cervix, paraffin sections were used to investigate the presence of HPVs 16 and 18 and p53 expression and mutation in six cases of MDA. By polymerase chain reaction, only one case was positive for HPV 16 and none was positive for HPV 18. By in situ polymerase chain reaction in the case positive for HPV 16, HPV 16 was detected in a low-grade squamous intraepithelial lesion overlying the MDA but not in the MDA itself. All of the MDAs were negative or only focally positive for p53 by immunohistochemistry. Our polymerase chain reaction DNA sequencing study failed to detect p53 mutation in exons 5 to 8 in those cases focally positive for p53 expression. These results suggest that MDA may be associated only occasionally with the high-risk HPVs or with p53 gene alterations.

Expression of cyclins and cyclin-dependent kinases in smooth muscle tumors of the uterus

To investigate the cell cycle regulatory mechanisms involved in the growth of smooth muscle tumors, we studied the expression of Ki-67, cyclins E and A, and their catalytic partners, the cyclin-dependent kinases cdk2 and cdc2 by using tissue specimens from benign and malignant smooth muscle tumors. These included 20 cases of usual leiomyoma (UL), 18 of cellular leiomyoma (CL), 8 of bizarre leiomyoma (BL), 8 of uncertain malignant potential tumors (UMP) and 20 of leiomyosarcoma (LMS). The proliferation rate detected by Ki-67 was low in normal myometrium and leiomyomas (UL, CL and BL), but it was markedly increased in LMS. The expression of the cyclins (E and A) and cdks (cdk2 and cdc2) was also low in normal myometrium and leiomyomas. However, the expression of these factors was markedly increased in LMS. In addition, a survival analysis using Log-rank test, revealed that LMSs with positive staining for cyclin A and with diffusely staining for cyclin E were associated with significantly shorter survival. Our results suggest that expression of cyclins and cdks may be involved in the growth control of uterine smooth muscle tumors.

Tranilast inhibits the proliferation of human coronary smooth muscle cell through the activation of p21waf1

Restenosis after percutaneous transluminal coronary angioplasty (PTCA) occurs due to vascular smooth muscle cell proliferation and migration. Recently, tranilast, an anti-allergic drug, has been used for the prevention of restenosis after PTCA. To determine the molecular mechanism involved, the effect of tranilast on the proliferation of human coronary smooth muscle cells (SMCs) was investigated. Tranilast arrested the proliferation of human coronary SMCs at the G0/G1 phase of the cell cycle. In association with this inhibitory effect, tranilast increased p21waf1 and p53 tumor suppressor factor, and decreased cyclin-dependent kinase 2 (CDK2) activity. These results suggest that tranilast inhibits the proliferation of human coronary SMCs during restenosis after PTCA via an induction of p21waf1 and p53. Tranilast may thus allow us to prevent restenosis after PTCA by interfering with this mechanism.

Expression of steroid receptors, Ki-67, and p53 in uterine leiomyosarcomas

The expression of estrogen receptor (ER), progesterone receptor (PR), tumor suppressor oncogene p53, and Ki-67 was compared in uterine smooth muscle tumors, including leiomyosarcoma (LMS), tumor of uncertain malignant potential (UMP), cellular leiomyoma (CL), bizarre leiomyoma (BL), and usual leiomyoma (UL). ER and PR were expressed in all ULs. PR was expressed in UL irrespective of the phase of the menstrual cycle; this staining was also observed in CL, UMP, and BL, although BL showed variable staining for ER. Compared to these tumors, the expression of both ER and PR was markedly reduced in LMS. The results of ER and PR transcripts by reverse transcription-polymerase chain reaction were compatible with those of immunohistochemistry. The number of Ki-67 positive cells in LMS was significantly higher than in UMP, BL, CL, and UL. p53 immunoreactivity was seen in 10 of 14 LMSs, and missense mutation in the p53 gene was found in 4 of 10 LMSs. These results suggest that abnormal expression of ovarian steroid receptors, p53, and Ki-67 is frequently associated with LMS of the uterus.

Mast cells in smooth muscle tumors of the uterus

Mast cells (MCs) have been reported in the myometrium and uterine smooth muscle tumors. We examined the number of MCs in various uterine smooth muscle tumors (including leiomyosarcomas) and assessed whether this feature might be of value in their pathologic diagnosis. The number of MCs in 95 uterine smooth muscle tumors, including 55 ordinary leiomyomas, 17 cellular leiomyomas, 8 bizarre leiomyomas, and 15 leiomyosarcomas, was counted using toluidine blue and immunohistochemical staining. The number of MCs that stained for tryptase was lowest in leiomyosarcoma and next lowest in ordinary leiomyoma; the number in each of these two groups was significantly lower than in the myometrium (p < 0.001). In cellular and bizarre leiomyomas, the number of MCs was significantly higher than in ordinary leiomyoma (p < 0.001 and p < 0.001, respectively) and leiomyosarcoma (p < 0.001 and p < 0.005, respectively). Statistical analysis revealed that counting the number of MCs and using a cut-off value of 16 MCs per high-power-field is useful for the differential diagnosis of leiomyosarcomas from cellular leiomyoma and bizarre leiomyoma, yielding 100% sensitivity and 96% specificity. The number of MCs was significantly lower in leiomyosarcomas at TNM stages III and IV than in those at stages I and II (p < 0.05), but there was no significant correlation between the number of MCs and patient survival. These results suggest that the number of MCs might be useful as part of a multivariate approach to the differential diagnosis of leiomyosarcoma from bizarre or cellular leiomyoma.

Immunohistochemical analysis of cell cycle regulatory gene products in normal trophoblast and placental site trophoblastic tumor

Intermediate trophoblast (IT) rarely gives rise to a placental site trophoblastic tumor (PSTT) To examine the different growth mechanisms present in normal and neoplastic IT, the expression of cell cycle regulatory molecules was compared at normal implantation sites and in PSTTs. Normal implantation sites in early gestation (19 patients) and PSTTs (6 patients) were immunohistochemically studied using antibodies against cytokeratin, human chorionic gonadotropin, and human placental lactogen to identify IT, and antibodies against Ki-67, cyclins (A, B, D1, and E), cyclin-dependent kinases (cdks), and p53 to investigate the proliferative activity of the trophoblast. Marked proliferative activity was observed in the trophoblast of the cell columns. Normal IT exhibited a very low labeling index for Ki-67, with negative expression for cdks and cyclins, except for cyclins B and E. The tumor cells of PSTT exhibited a high labeling index for Ki-67 with positive expression for all the cyclins and cdks examined. Expression of p53 was identified in tumor cells of PSTTs and the distribution of p53-positive cells correlated topographically with that of the cyclin A-positive cells. The transformed IT of PSTT has high proliferative activity with an abnormal expression of cell cycle regulatory molecules, which is not observed in normal IT.

Distribution and heterogeneity of mast cells in the human uterus

Mast cells (MCs) are widely distributed in most human tissues. Those cells that contain only tryptase are designated as T-MCs, while those that also contain chymase are referred to as TC-MCs. This study uses immunohistochemical staining for tryptase and chymase to assess the distribution and heterogeneity of these two types of MCs in the human uterus. The greatest number of MCs was found in the inner (i.e. luminal) half of the myometrium, with this area containing approximately equal proportions of T-MCs and TC-MCs. There were fewer MCs in the outer half of the myometrium and the cervix, but the proportion of TC-MCs in both of these areas was substantially higher. In contrast, the endometrium contained significantly fewer MCs, but proportionally more T-MCs. There was no change in the number of MCs between the proliferative and secretory phases of the menstrual cycle; however, there was a significantly lower number in all areas after menopause. Most of the MCs were observed in close association with uterine smooth muscle cells, as well as in the vicinity of fibroblasts and collagen, and it appears they may play an important role in the reconstruction of uterine tissues during the menstrual cycle.

Effects of a GnRH analogue on human smooth muscle cells cultured from normal myometrial and from uterine leiomyomal tissues

Leiomyomas are tumours of uterine smooth muscle tissue that are oestrogen and progesterone dependent. When explants of these tumours were grown in culture, the proliferating tissue formed characteristic ball-like aggregates (BLA), rather than the usual hill and valley (HV) pattern of growth of normal myometrial tissue in culture. Immunocytochemical staining with fluorescein isothiocyanate (FITC)-labelled gonadotrophin-releasing hormone (GnRH) revealed that both myometrial and leiomyomal cells have membrane receptors for this hypothalamic releasing hormone. Furthermore, polymerase chain reactions (PCR) with primer sets that were specific for GnRH receptor mRNA, as well as GnRH mRNA, showed that transcripts for both of these nucleic acids are present in myometrial and leiomyomal tissues. The treatment of cultured explants of leiomyomal tissue with a GnRH analogue (buserelin, HOE766) diminished the formation of BLA, but this synthetic hormone had only a moderate effect on the HV topography of normal myometrial tissue. A colorimetric assay indicated that GnRHa inhibited cell proliferation in leiomyomal tissue in a dose-dependent manner. Western blotting, to detect the expression of G1 phase cell cycle-related gene products, showed that cyclin E and p33cdk2 formation in leiomyomas were inhibited by high concentrations of GnRHa. In conclusion, GnRHa might suppress leiomyomal growth by interfering with the expression of cell cycle factors.

In-vitro model of uterine leiomyomas: formation of ball-like aggregates

To clarify the biological characteristics of uterine leiomyomas, cells explanted and cultured from uterine leiomyomas and from normal myometrial tissue were observed by time-lapse cinemicrography and phase-contrast microscopy. The histological characteristics were evaluated by electron microscopy and immunofluorescence microscopy, and these observations revealed significant differences. By time-lapse cinemicrography, the cells cultured from leiomyomas and myometrium differed in their behaviour. Cells from the myometrium started to grow in parallel with the cell's major axis and formed topographically uniform hills and valleys by day 21 of culture. In contrast, the cells from leiomyomas started to grow irregularly, as if having no contact inhibition, and formed ball-like aggregates of cells by day 21 of culture. The aggregates resembled the nodules of leiomyoma in vivo. Ultrastructurally, cells from both leiomyomas and myometrium had typical features of smooth muscle. Immunofluorescently, a different distribution of alpha-smooth muscle actin-positive filaments and different staining of cellular fibronectin and N-cadherin between the cells from leiomyomas and myometrium were observed, which may contribute in part of the different behaviour of the cells. Given that the explant cell culture system resembles the features of uterine leiomyomas in vivo, this suggests that it can be used as an in-vitro model.