E-CADHERIN CODING GENE (CDH1) AND NONSYNDROMIC CLEFT LIP WITH OR WITHOUT CLEFT PALATE: IS THERE ANY ASSOCIATION?

Epithelial to Mesenchymal Transition (EMT) is an important process involved in cancer, embryogenesis and organ development. Its role in nonsyndromic cleft lip with or without cleft palate (NSCL/P) has been extensively investigated and successfully linked to the disease. In this study, we focused on a gene, CDH1, encoding for E-cadherin, a key protein in EMT. We carried out an association study on an Italian sample group, genotyping four single nucleotide variations within the CDH1 gene, in order to verify the potential role of this gene in NSCL/P etiology. Neither the haplotype nor the family-based association test revealed any association between the genotyped SNPs and the pathology. Our results demonstrate that, in our Italian sample study, the analyzed single nucleotide polymorphisms are not associated to NSCL/P.

Evidence of LEF1 fetal-maternal interaction in cleft lip with or without cleft palate in a consistent Italian sample study.

Epithelial mesenchymal transformation is considered a cardinal process in orofacial development. Several molecular players appear to be involved in this delicate mechanism; the activation of LEF1 transcription factor by transforming growth factor beta 3 seems to be a key step for the correct flow of events. The failure of orofacial processes during embryonic development may provoke cleft lip and/or cleft palate malformations. The scope of the present investigation was to verify whether genetic variants at LEF1 could influence the risk of orofacial clefting. The approach was a family based association study involving a total of 512 Italian patients and their parents, 401 having cleft lip with or without cleft palate (CL/P) and 111 with cleft palate only (CPO). Haplotype association analysis provided moderate evidence of an association with clefting (p 0.01). A log-linear likelihood-based method was used to verify maternal and foetal-maternal association. An association between the maternal genotype and the occurrence of CL/P was observed at two polymorphic loci, at rs10022956 (P = 0.0049) and rs10025431 (P = 0.0065) respectively, while a foetal-maternal effect modulating the risk of clefting was found at locus rs10025431 (P = 0.0071). These data further corroborate the importance of the mother's genotype with regard to susceptibility to malformations and early-onset diseases.

The MTHFD1 gene is not involved in cleft lip with or without palate onset among the Italian population.

Nonsyndromic cleft lip with or without cleft palate (CL/P) is the most common orofacial malformation, having a non-Mendelian and multifactorial aetiology. It has been shown that polymorphic variants of genes encoding key proteins of folate and methionine metabolism might be important maternal risk factors for having a child with these craniofacial anomalies. The aim of this study was to evaluate the role of two polymorphisms of the methylenetetrahydrofolate dehydrogenase 1 (MTHFD1) gene, the A1958G and the G401A variants, on the risk of CL/P in the Italian population. A1958G and G401A polymorphism genotyping of MTHFD1 was performed on 216 CL/P triads, (patient and parents), for this study by restriction endonuclease digestion of PCR products. Linkage disequilibrium between markers and disease was tested using both pairwise and haplotype analyses. In our case-parents triad design no significant association between MTHFD1 and the disease is evident. Our data do not support MTHFD1 involvement in CL/P onset among the Italian population.

FHIT oncosuppressor gene expression profile in human anal cancers.

The FHIT gene, a member of the histidine triad gene family, is a tumor suppressor gene exhibiting deletions in the majority of human cancers. Aberrant transcripts of this gene have been found in about 50% of esophageal, stomach and colon carcinomas. Little is known about the molecular mechanisms involved in malignant transformation of the lining cells of the anus. In this study FHIT gene expression was investigated in this particular kind of human cancer. FHIT expression was comparatively analyzed at the mRNA level, by RT-PCR, in squamous anal cancers, normal anal tissue and peripheral blood samples. cDNA analyses showed variability in FHIT transcripts, without apparent effects on the predicted amino acid sequence. These different FHIT mRNAs could represent transcripts from an alternative splicing event. Our data indicate that the FHIT mRNA detected in anal cancers and in normal samples is heterogeneous. Immunohistochemical data suggest that the Fhit protein is expressed only in a fraction of the tumor cells, while it is strongly expressed in the epithelial cells of glands of the normal anal mucosa. The absence or poor expression of the Fhit protein in anal cancers suggests a role for this tumor suppressor gene product, as a risk factor, in the onset of this human cancer, as reported before for other human gastrointestinal tumors.

Combined carriership of TLR9-1237C and CD14-260T alleles enhances the risk of developing chronic relapsing pouchitis.

AIM: To investigate the single nucleotide polymorphisms (SNPs) in genes involved in bacterial recognition and the susceptibility to pouchitis or pouchitis severity. METHODS: Analyses of CD14 -260C>T, CARD15/NOD2 3020insC, Toll-like receptor (TLR)4 +896A>G, TLR9 -1237T>C, TLR9+2848G>A, and IRAKM + 22148G>A SNPs were performed in 157 ileal-pouch anal anastomosis (IPAA) patients (79 patients who did not develop pouchitis, 43 infrequent pouchitis patients, 35 chronic relapsing pouchitis patients) and 224 Italian Caucasian healthy controls. RESULTS: No significant differences were found in SNP frequencies between controls and IPAA patients. However, a significant difference in carriership frequency of the TLR9-1237C allele was found between the infrequent pouchitis and chronic relapsing pouchitis groups [P = 0.028, oddos ratio (OR) = 3.2, 95%CI = 1.2-8.6]. This allele uniquely represented a 4-locus TLR9 haplotype comprising both studied TLR9 SNPs in Caucasians. Carrier trait analysis revealed an enhanced combined carriership of the alleles TLR9 -1237C and CD14 -260T in the chronic relapsing pouchitis and infrequent pouchitis group (P = 0.018, OR = 4.1, 95%CI = 1.4 -12.3). CONCLUSION: There is no evidence that the SNPs predispose to the need for IPAA surgery. The significant increase of the combined carriership of the CD14 -260T and TLR9 -1237C alleles in the chronic relapsing pouchitis group suggests that these markers identify a subgroup of IPAA patients with a risk of developing chronic or refractory pouchitis.

Ornithine decarboxylase, polyamines and CD11b expression in HL-60 cells during differentiation induced by retinoic acid.

Polyamines (PA) and retinoic acid affect mammalian cell growth, differentiation and apoptosis. Retinoic acid induces granulocytic differentiation of mieloid cell lines and, during this process, is responsible for the expression of CD11b, a surface antigen. In this study we investigate the effects of retinoic acid on HL-60 cells, monitoring ornithine decarboxylase (ODC) activity (enzyme rate of PA), putrescine (PUT), spermidine (SPD), spermine (SPM) levels, CD11b myeloid surface marker differentiation, cell cycle, and apoptosis. ODC activity and PUT levels are correlated with mieloid cell differentiation induced by retinoic acid treatment. Only the ODC/PUT ratio is connected with retinoic acid treated HL-60 cells. Treated cultures show a decrease of proliferation and a cell block in the G0/G1 phase, with consequent diminished S phase. The G0/G1 and S phases are significantly related to ODC activity and to PUT and SPD behavior, whereas in differentiating condition only the decrease of PUT is related to the S phase. CD11b expression, stimulated by retinoic acid treatment, is associated with the SPM trend. Total PA behavior agrees with apoptotic cell increase after 96 h of stimulation. Our data show that retinoic acid treatment modifies ODC activity and the turnover of PA. PUT, SPD and SPM, therefore, have a different role, and may be involved in the differentiative/apoptotic program of retinoic acid treated HL-60 cells.

Extracellular glycosaminoglycan changes in healthy and overgrown gingiva fibroblasts after cyclosporin A and cytokine treatments.

BACKGROUND: It has been demonstrated that cyclosporin A (CyA) blocks the immune system, acts on cytoskeleton and stimulates the production of extracellular matrix (ECM) and transforming growth factor-beta1 (TGF-beta1). This cytokine, such as transforming growth factor-alpha (TGF-alpha), induces deposition of glycosaminoglycans (GAG), proteoglycans and collagen fibres in the ECM. METHODS: In this work, we examined the effect induced by CyA, TGF-beta1 and TGF-alpha on cultures of healthy and overgrown human gingival fibroblasts in order to evaluate the glycosaminoglycan, cytoskeletal changes and the behaviour of fibroblasts after concanavalin A (Con A) treatment. Moreover, we examined gingival biopsies by Alcian blue histochemical staining and electron transmission microscopy. RESULTS: Total and extracellular sulphated GAG in overgrown gingiva specimens and in derived fibroblast cultures treated with CyA and cytokines were significantly higher than controls. The action of cytokines was increased (P < or = 0.01) compared with CyA with a greater effect of TGF-alpha in comparison with TGF-beta1; the electron microscopy showed ECM accumulation. The agglutinations showed the heterogeneity of fibroblast populations. CONCLUSIONS: Stimulation with Con A showed that the fibroblast population had cell surface heterogeneity, and could respond in a different way to both CyA and cytokine stimulus. Moreover, increased synthesis of GAG in overgrown gingiva compared with synthesis in normal fibroblasts before CyA treatment suggests a possible genetic origin of damage. As not all CyA-treated patients develop gingival overgrowth, a genetic predisposition may explain the different responses of gingival fibroblast populations.

Maternal MTHFR variant forms increase the risk in offspring of isolated nonsyndromic cleft lip with or without cleft palate.

The pathogenesis of cleft lip with or without cleft palate (CL/P) is complex; its onset could be due to the interaction of various genetic and environmental factors. Recently MTHFR functional polymorphisms were found to increase the risk of this common malformation; however, this finding is still debated. We investigated 110 sporadic CL/P patients, their parents and 289 unrelated controls for c.665C>T (commonly known as 677C>T; p.Ala222Val) and c.1286A>C (known as 1298A>C; p.Glu429Ala) polymorphism in the MTHFR gene. Transmission disequilibrium test (TDT) showed no distortion in allele transmission. Nevertheless, association studies revealed significant differences in allele frequencies between mothers of CL/P patients and controls. This work supports the hypothesis that a lower MTHFR enzyme activity in pregnant women, mostly related to the c.665C>T variant form, is responsible for a higher risk of having CL/P affected offspring.

Bronchial branching correlates with specific glycosidase activity, extracellular glycosaminoglycan accumulation, TGF beta(2), and IL-1 localization during chick embryo lung development.

During organ differentiation, cell-extracellular matrix (ECM) interactions are required. The components of the ECM, such as glycosaminoglycans, fibronectin, laminin, and collagens, change in relation to cytokine and enzyme activity. Moreover, glycosaminoglycans (GAGs) are components of the ECM that play an important role in both cytokine regulation and cell activities. In this work we studied the accumulation of hyaluronic acid and chondroitin sulfate and heparan sulfate proteoglycans (PGs), beta-N-acetyl-D-glucosaminidase activity, the presence of transforming growth factor beta(2) (TGF beta(2)), and interleukin-1 (IL-1), and the localization of fibronectin, laminin, and collagen I and IV during the early stages of chick embryo lung development. We also determined the levels of hyaluronic acid, chondroitin sulfate, dermatan sulfate, and heparan sulfate GAGs and the activity of beta-N-acetyl-D-glucosaminidase with biochemical methods. Our data show that beta-N-acetyl-D-glucosaminidase activity increases in each cell, especially in the epithelial growth front at the emergence of each bronchial bud, where hyaluronic acid and IL-1 are located in the surrounding mesenchymal areas. Chondroitin sulfate and heparan sulfate PGs, fibronectin, laminin, and collagen I and IV are evident in the area near the basal membrane along the sides where the forming structures are stabilized. Biochemical data show that beta-N-acetyl-D-glucosaminidase activity increases in cells during lung development and is related to GAG decrease and to modifications of the nonsulfated/sulfated GAG ratio. These modifications could change cytokine activity and play an important role in bronchial branching development.

Effect of probiotic strains on interleukin 8 production by HT29/19A cells.

OBJECTIVES: Promising results from clinical studies on the effect of probiotics as maintenance therapy in inflammatory bowel disease and in the prevention of onset of pouchitis ask for studies to unravel the still poorly understood mechanism of action of probiotics. METHODS: To evaluate whether the probiotic bacteria that were used in the clinical studies (VSL#3, Escherichia coli Nissle 1917, and Lactobacillus GG) are able to induce chemokine production in epithelial cells, HT29/19A monolayers were incubated with cell debris and cell extract fractions of single strains of the probiotic bacteria in doses ranging from 10(3) to 10(9) colony-forming units/ml for 32 h. Supernatants were measured for interleukin 8 by ELISA. RESULTS: Lactobacilli and bifidobacteria strains from VSL#3 and Lactobacillus GG did not induce interleukin 8, whereas both cell debris and cell extracts from E. coli Nissle 1917 induced interleukin 8 production in a dose-dependent way. Cell extracts from streptococcal strains induced interleukin 8 when applied at high concentrations. CONCLUSIONS: Probiotic Gram-positive bacteria did not induce interleukin 8, whereas the nonpathogenic, Gram-negative E. coli Nissle 1917 strain induced interleukin 8 in a dose-dependent way in this culture model. These results suggest that probiotic Gram-positive bacteria and E. coli Nissle 1917 may exert their beneficial effects on the host by a different mechanism of action.

Fhit protein expression in human gastric cancer and related precancerous lesions.

The FHIT gene is altered in several types of tumors and abnormal expression of Fhit protein have also been reported in some preneoplastic lesions. We have determined the Fhit expression on histological samples of 26 patients affected by preneoplastic lesions who developed a gastric cancer within 2 years. The expression of the Fhit protein was always present in all preneoplastic lesions, while the Fhit protein immunostaining was distributed unevenly in 10 cases and completely lost in 6. The complete loss of Fhit expression only in areas of neoplastic low differentiation suggests that FHIT gene takes part in late gastric carcinogenesis.

Phospholipase C delta2 expression characterizes the neoplastic transformation of the human gastric mucosa.

The expression, cellular distribution, and activity of PIP(2)-specific phospholipase C (PLC) in healthy human gastric-mucosa cells have been recently studied in our laboratories and a direct evidence for an almost exclusive expression of PLC beta isoforms, with the exception of PLC beta4, has been provided. These results addressed our attention to possible modification of PLC expression and activity during neoplastic transformation of the human gastric mucosa. In the present article we present results indicating that PLC delta2 is markedly expressed in type II intestinal metaplasia and in the adenocarcinoma whereas traces of other PLC isoforms were sometime detected. Interestingly, we found that type I intestinal metaplasia was in the majority of the cases PLC delta2-negative, but when expressed, this type of metaplasia generally considered as benignant, always evolved toward neoplastic transformation. These results therefore readdress the question of surveillance of the patients with type I intestinal metaplasia and suggest that PLC delta2 expression might be a possible marker of gastric malignant transformation.

Lack of mutations of type 1 11beta-hydroxysteroid dehydrogenase gene in patients with abdominal obesity.

There is increasing evidence that in human obesity, particularly the abdominal phenotype, the activity of the hypothalamic-pituitary-adrenal (HPA) axis is disregulated. At least two distinct alterations have been reported: one is characterized by several neuroendocrine abnormalities and hyperresponsiveness of the HPA axis to different neuropeptides, the other is characterized by elevated cortisol traffic and probably by supranormal cortisol production. The 11beta-hydroxysteroid dehydrogenase (11beta-HSD) enzymes interconvert cortisol and cortisone in human. Two different isoforms have been identified. A possible modification of the activity of the enzyme 11beta-HSD1 in subjects with abdominal obesity has been described in the literature. We decided to test the hypothesis that mutated isoforms of type 11beta-HSD1 protein could be responsible for alterations of cortisol metabolism in patients with abdominal obesity. A mutational screening of the whole coding sequence and exon-flanking regions of the 11B-HSD1 gene has been performed in 8 patients. The main results of our study are the exclusion of a common association of 11beta-HSD1 mutations to obesity and the identification of two novel allelic variants for the gene 11beta-HSD1 in the Italian population, not previously described in any database.

Correlation among amniotic fluid index (AFI), cesarean section rate, and labor length in inducted pregnancies beyond 41 weeks' gestation with unfavorable cervix.

This paper evaluated how the pregnancy after 41 completed weeks' gestation with amniotic fluid index (AFI) > 6 has a slower response to the prostaglandin E2 (PGE2) induction. Eighty-one post-term pregnancies (41 completed gestations' weeks) with unfavorable cervix were considered in this follow-up. Induction was performed by means of intracervical PGE2 gel (Dinoprostone 0.5 mg). After 12 hours, if the cervix was still unfavorable, then another gel administration followed. Cases that had oxytocin administration were excluded from the study. The median time of spontaneous delivery in the overall series was 25 hours, 14 minutes. We had 18 cases of cesarean section (22.2%). In the group of pregnancies with AFI > 6 (60 cases) and in the group with AFI < or =6 (21 cases), the median time of spontaneous delivery was 29 hours, 25 minutes and 23 hours, 39 minutes, respectively (p-value = 0.02). The rate of cesarean sections was 26.67 and 9.52, respectively in the two groups (p-value >0.05). Two out of four cases of cesarean sections for fetal distress belonged to the group of AFI > 6. All the 14 cases of cesarean section for dystocia belonged to the group with AFI > 6. Considering just patients who did not deliver within 12 hours (57 cases), median time of spontaneous delivery was 33 hours and 24 hours 40 minutes for group AFI > 6 (42 cases) and AFI < or =6 (15 cases), respectively (p-value = 0.0009). Thirty-one cases out of 57 had another PGE2 gel administration. Adjusted odds ratio was 0.33 (0.16-0.65, 95% C.I.) for AFI < or =6 versus AFI > 6.

The natural history of the metabolic syndrome in young women with the polycystic ovary syndrome and the effect of long-term oestrogen-progestagen treatment.

OBJECTIVE: Little is known about the natural history of polycystic ovary syndrome (PCOS), although preliminary data indicate that affected women are more susceptible than the general population to diabetes and cardiovascular diseases at post-menopausal ages. The aim of this study was to follow-up all main features of the metabolic syndrome in a group of young women with PCOS and to investigate the long-term effects on metabolism and body composition of oestrogen-progestagen (OP) compounds, which are frequently used in these women to treat hyperandrogenism and related clinical features. DESIGN: Long-term follow-up study. SUBJECTS AND METHODS: Thirty-seven women with PCOS were re-evaluated 10.3 +/- 0.8 years (range 6-18 years) after their first assessments (age: before 19.8 +/- 4.9 years; after 29.9 +/- 4.4 years). When first examined, women were instructed to follow a hypocaloric diet if they were obese plus OP, if they agreed to such treatment. Main anthropometric parameters, basal sex hormones and lipids, fasting and glucose-stimulated glucose and insulin levels and several clinical data were recorded before and after follow-up. RESULTS: In the whole group of women with PCOS we found no changes in body weight and fat mass, whereas both the waist-to-hip ratio and the waist-to-thigh ratio were significantly reduced. No significant changes occurred in mean fasting and glucose-stimulated glucose and insulin concentrations, whereas a significant increase in high-density lipoprotein-cholesterol was found. No significant changes occurred in testosterone levels. During the follow-up period 16 women took OP for an average of 97 +/- 18 months (range 12-180 months) (OP-users) whereas 21 women never took OP (non-OP-users). All OP-users were still taking OP when re-evaluated at the follow-up examination. With respect to baseline values, body mass index was higher in non-OP-users than in their counterparts. Waist circumference (P < 0.025), the waist-to-hip (P < 0.05) and the waist-to-thigh (P < 0.01) ratios decreased significantly only in the OP-users. In addition, percentage changes in waist circumference (P < 0.05) and waist-to-hip ratio (P < 0.05) during the follow-up period were significantly different between the groups. Glucose tolerance (as area under the curve (AUC)) improved (P < 0.05) in OP-users but not in non-OP-users. Moreover, compared to baseline values, basal insulin levels were significantly (P < 0.01) reduced in OP-users but not in non-OP-users. On the contrary, no significant change was found in insulinAUC in the former, whereas it significantly increased (P < 0.05) in the latter. Accordingly, fasting C-peptide decreased (P < 0.05) in OP-users, whereas both fasting (P < 0.01) and stimulated (P < 0.01) C-peptide significantly increased in non-OP-users. Changes in fasting or stimulated insulin and C-peptide in non-OP-users were not associated with parallel changes in testosterone levels. Total cholesterol and triglycerides did not change in either group, but HDL-cholesterol increased (P < 0.05) only in OP-users. Sex hormone-binding globulin concentrations increased significantly (P < 0.01) in OP-users, without any significant change in non-OP-users. Testosterone concentrations did not change significantly in either group, but the testosterone: SHBG ratio significantly decreased in OP-users (P < 0.05) but not in the non-OP-users. Among the clinical features, acanthosis nigricans significantly (P < 0.01) worsened in non-OP-users but not in the OP-users, without any significant change in the hirsutism and acne scores. Pregnancy rates during the follow-up were similar in both groups. CONCLUSIONS: These data indicate that hyperinsulinaemia and insulin resistance tended to worsen spontaneously in women with PCOS, without any worsening of the hyperandrogenism. Long-term oestrogen-progestagen treatment countered this tendency, probably because it improved the pattern of body fat distribution, by reducing abdominal fat depots.

Nuclear association of tyrosine-phosphorylated Vav to phospholipase C-gamma1 and phosphoinositide 3-kinase during granulocytic differentiation of HL-60 cells.

The granulocytic differentiation of HL-60 cells induced by all-trans retinoic acid was accompanied by a progressive tyrosine phosphorylation of specific proteins in either cells or isolated nuclei. Among these phosphoproteins, we identified the Vav adaptor in whole cells as well as in the inner nuclear compartment, where the increase in its tyrosine phosphorylation level was more conspicuous. We also demonstrated the differentiation-dependent association of nuclear phosphorylated Vav to phospholipase C-gamma1 and to the p85 regulatory subunit of phosphoinositide 3-kinase. The role of the Vav/phospholipase C-gamma1/phosphoinositide 3-kinase phosphoprotein complexes in the nuclei of HL-60 induced to differentiate along the granulocytic lineage is discussed.

Thrombopoietin enhances the alpha IIb beta 3-dependent adhesion of megakaryocytic cells to fibrinogen or fibronectin through PI 3 kinase.

The effect of thrombopoietin (TPO) on the functional activity of surface alpha IIb beta 3 (GPIIbIIIa) was investigated in both primary human megakaryocytic cells, derived from peripheral blood CD34+ cells, and HEL hematopoietic cell line. TPO (100 ng/mL) induced a sixfold to ninefold enhancement of adhesion of both primary megakaryocytic and HEL cells to plates coated with either fibrinogen or fibronectin and a parallel increase of immunoreactivity to the PAC1 monoclonal antibody (MoAb) and fluorescein isothiocyanate-fibrinogen, both of which recognize an activated state of alpha IIb beta 3. The enhanced adhesion to fibrinogen or fibronectin was mediated by the Arg-Gly-Asp (RGD) recognition sequence of alpha IIb beta 3, as it was abolished by pretreatment of cells with saturating concentrations of RGDS peptide. A MoAb specific for the alpha IIb beta subunit of alpha IIb beta 3 also inhibited cell attachment to fibrinogen or fibronectin, while MoAb to anti-alpha v beta 3 or anti-alpha 5 integrins were completely ineffective, clearly indicating that alpha IIb beta 3 participates in this association. A role for PI 3 kinase (PI 3-K) in the TPO-mediated increase in alpha IIb beta 3 function in megakaryocytic cells was suggested by the ability of the PI 3-K inhibitor wortmannin (100 nmol/L) and antisense oligonucleotides directed against the p85 regulatory subunit of PI 3-K to completely block the TPO-induced increase in alpha IIb beta 3 integrin activity upon TPO stimulation. The modulation of adhesiveness to extracellular matrix proteins containing the RGD motif mediated by TPO likely plays a physiologic role in megakaryocytopoiesis, as pretreatment of CD34+ cells with RGDS or anti-alpha IIb MoAb significantly reduced the number of megakaryocytic colonies obtained in a fibrinclot semisolid assay.

Protein kinase C isoforms undergo quantitative variations during rat spermatogenesis and are selectively retained at specific spermatozoon sites.

Signal transduction elements, including protein kinase C, have been identified in mammalian spermatozoa. In order to evaluate the pattern of expression and the subcellular localization of nine different protein kinase C isoforms in the course of spermatogenesis, we utilized quantitative electron microscopy immunocytochemistry on thin sections of rat seminiferous tubules. The results indicate a progressive reduction of the protein kinase C isoforms present in the early stages of spermatogenesis, so that in late spermatids none of them is present in the nucleus, while the isoforms alpha, gamma and beta II are specifically retained in the acrosome, the isoforms beta I and zeta in the neck, and the isoform epsilon in the tail. These isoforms, except for beta II, are maintained at the same sites in spermatozoa. Western blotting analysis indicates the presence of alpha and gamma isoforms in the head subfraction, and of beta I, zeta and epsilon isoforms in the tail subfraction of spermatozoa. These findings suggest that specific protein kinase C isoforms may be functionally involved in some events of spermatozoa differentiation and, eventually, in the fertilization process.

Nuclear phosphoinositide-specific phospholipase C, phosphatidylinositol 4,5-bisphosphate and protein kinase C during rat spermatogenesis.

Presence and intracellular distribution of phosphoinositide-specific phospholipase C, phosphatidylinositol 4,5-bisphosphate and protein kinase C have been investigated in rat maturing germ cells and spermatozoa. The isoforms beta 1 and gamma 1 of phosphoinositide-specific phospholipase C were immunologically identified and found to be predominantly nuclear or cytoplasmic and nuclear, respectively. The two enzymes were present in the maturing cell lineage of the seminiferous tubule, except for the nucleus of late spermatids, and absent in spermatozoa, in which, however, a phosphoinositide-specific phospholipase C activity persisted, due to yet uncharacterized enzyme(s). Protein kinase C paralleled these developmental changes, and was completely down-regulated in both total cell homogenates and isolated nuclei obtained from spermatozoa. On the contrary, phosphatidylinositol 4,5-bisphosphate, present at the nuclear level in all cell types, accumulated in the nuclei of late spermatids and spermatozoa. These data support the contention that the spermatozoon nucleus stores a lipid-dependent signaling apparatus which could be reactivated either during sperm maturation or at fertilization.

Nuclear translocation of protein kinase C-alpha and -zeta isoforms in HL-60 cells induced to differentiate along the granulocytic lineage by all-trans retinoic acid.

We investigated whether members of the protein kinase C (PKC) family of enzymes were involved in the nuclear events underlying granulocytic differentiation induced by 10(-6) M all-trans retinoic acid (ATRA) in HL-60 cells. PKC activity was analysed by using a serine substituted specific peptide which enabled the evaluation of the whole catalytic activity of both Ca2+ -dependent and Ca2+ -independent PKC isoforms. In parallel, the subcellular distribution of various PKC isoforms was evaluated by Western blot, immunoprecipitation and in situ immunocytochemistry analyses. The level of PKC catalytic activity in the nuclei of HL-60 cells significantly (P < 0.01) and progressively increased from 1 h of ATRA treatment onwards. Consistently, PKC-alpha and -zeta showed a striking and selective accumulation inside the nucleus upon treatment with ATRA. On the other hand, PKC-beta I and -beta II, the only two other isoforms present at nuclear level, did not show any significant modification upon ATRA treatment. The remaining PKC isoforms were not detectable inside the nucleus and showed only modest and non-significant variations, also in whole cell homogenates, upon ATRA treatment, except PKC-delta which showed a progressive down-regulation. Our data suggest that a selective nuclear translocation of PKC-alpha and -zeta might be involved in the process of granulocytic differentiation induced by ATRA in HL-60 cells.