[The risk factors for regional lymph node metastasis of mismatch repair deficient colorectal cancer]

Objective: To explore the risk factors for regional lymph node (RLN) metastasis in colorectal cancer patients with mismatch repair deficiency (dMMR). Methods: The data of 357 dMMR colorectal cancer patients who underwent surgery in National Cancer Center from January 2012 to December 2016 was retrospectively analyzed. Univariate and multivariate analysis were used to identify the risk factors for RLN metastasis. Results: Among the 357 patients, 204 were male and 153 were female, 61.6% (220/357) lesion located in right half colon, while the other 16.2% (58/357) located in rectum. Univariate analysis showed that tumor size, differentiation, lymphovascular invasion, tumor deposit, postoperative pathologic T stage (pT), the number of negative lymph nodes and the expression of the MSH6 protein were significantly associated with RLN metastasis (P<0.05). All of the patients with well differentiation tumors (15 patients) or staged pT1 (13 patients) had no RLN metastasis. Multivariate analysis showed that tumor differentiation (OR=2.582, 95%CI=1.567-4.274, P<0.001), pT (OR=3.778, 95%CI=1.448-12.960, P=0.015) and the expression of MSH6 protein (OR=2.188, 95%CI=1.159-4.401, P=0.021) were independent risk factors for RLN metastasis. Conclusions: The postoperative pT stage, tumor differentiation and the expression of MSH6 protein are independent risk factors for RLN metastasis of dMMR colorectal cancer. Preoperative assessment of these factors may further improve the accuracy of predicting the risk of RLN metastasis.

[Clinicopathological and prognostic features of young onset patients with middle-low rectal cancer received neoadjuvant chemoradiotherapy]

Objective: To explore the clinicopathological and prognostic features of young onset patients with middle-low rectal cancer who received neoadjuvant chemoradiotherapy (NCRT). Methods: After NCRT, a total of 441 patients with primary middle-low rectal cancer treated with radical surgery at the Cancer Hospital, Chinese Academy of Medical Sciences (CHCAMS) from January 2004 to December 2016 were included. According to the age of disease onset, the patients were divided into the young group (51cases) and the middle-old group (390 cases), and the clinicopathological characteristics and survival of these patients were analyzed. Results: In the young group, 68.6% of patients received radical surgery within 7 weeks after NCRT, which was higher than 52.8% in the middle-old group (P=0.047). The stage ypTNM Ⅲ in the young group was 51.0%, higher than 34.1% in the middle-old group (P=0.027). The stage ypN+ in the young group was 51.0%, higher than 34.1% in the middle-old group (P=0.047), The incidence of disease progression in the young group was 39.2%, higher than 25.1% in the middle-old group (P=0.049). The incidence of distant metastasis in the young group was 35.3%, higher than 21.5% in the middle-old group(P=0.044). Most cases of disease progression occurred in the first 3 years after surgery for the young group, especially in the second year after surgery, the incidence of disease progression in the young group was 55.0%, higher than 26.5% in middle-old group (P=0.025). The 3-year and 5-year disease-free survival (DFS) rates for the young group were 63.7% and 58.2%, lower than 81.0% and 74.3% in the middle-old group (P=0.016), respectively. The 3-year and 5-year overall survival in the middle-old group (OS) rates for the young group were 85.4% and 69.2%, lower than 93.6% and 84.1% in the middle-old group (P=0.033), respectively. The multivariate analysis showed that, response of primary tumor (HR=4.804, 95% CI: 1.360-16.973) and total number of dissected lymph nodes (HR=4.336, 95% CI: 1.739-10.809) in the young group were independent prognostic factors related to DFS. The total dissected number of lymph nodes(HR=3.295, 95% CI: 1.076-10.091)was an independent prognostic factor related to OS. In the middle-old group, response of primary tumor (HR=2.626, 95% CI: 1.354-5.091), ypTNM stage (ypTNM Ⅲ: HR=5.837, 95% CI: 2.968-11.479) and tumor location distance from the anal verge (HR=0.500, 95% CI: 0.308-0.812) were independent prognostic factors related to DFS. Lymphovascular invasion (HR=0.500, 95% CI: 0.308-0.812) and ypTNM stage (ypTNM Ⅲ: HR=16.322, 95% CI: 5.049-52.771) were independent prognostic factors related to OS. Conclusions: Young onset rectal cancer patients are associated with shorter operation time interval, advanced pathological stage and poorer prognosis. More intensive adjuvant treatment and post-treatment surveillance should be conducted to young onset rectal cancer with NCRT.

[Clinicopathological characteristics and prognostic analysis of patients with pathological complete response and near complete response after neoadjuvant treatment of rectal cancer]

Objective: To investigate the clinicopathological characteristics and prognosis of rectal cancer patients with pathological complete response and near complete response after neoadjuvant therapy. Methods: The clinicopathological data of patients who underwent neoadjuvant chemoradiotherapy plus radical surgery of rectal cancer in the Cancer Hospital of Chinese Academy of Medical Sciences from January 2004 to December 2016 were retrospectively collected. The clinicopathological characteristics and prognostic factor of patients with pathological complete response and near complete response were analyzed. Results: The clinical data of 142 patients were collected. There were 93 males and 49 females, aged from 24 to 81 years. The median disease-free survival was 53.9 months and the median overall survival was 55.0 months. Univariate analysis showed that the maximum diameter of scar or lesion, the status of lymph node metastasis and the distance between the lower edge of tumor and anal edge were associated with disease-free survival time; the maximum diameter of scar or lesion and the status of lymph node metastasis were associated with overall survival time. Multivariate Cox proportional hazards regression analysis showed that patients with scar or lesion diameter>3 cm (HR=4.406,95%CI:1.619-12.006), positive lymph node metastasis status (HR=4.102,95%CI:1.461-11.513) and tumor lower margin to anal margin distance ≤4 cm (HR=18.171,95%CI:2.357-140.073) had shorter disease-free survival time.The patients with scar or lesion diameter>3 cm (HR=8.573,95%CI:1.630-45.099) and lymph node metastasis status (HR=4.721, 95%CI:1.068-20.860) had shorter overall survival time. Conclusions: The overall prognosis of patients with pathological complete response or near complete response after neoadjuvant therapy for rectal cancer is better. The distance between the lower margin of the tumor and the anal edge, the status of lymph node metastasis and the maximum diameter of scars or lesion were the related factors affecting the prognosis of patients with rectal cancer.

[Long-term results of multicenter study based on childhood acute lymphoblastic leukemia 2005 protocol]

Objective: To evaluate the long-term efficacy and prognostic factors of childhood acute lymphoblastic leukemia (ALL) enrolled in Shanghai Children's Medical Center-Acute Lymphoblastic Leukemia-2005(SCMC-ALL-2005) multicenter study. Methods: Between May 2005 and December 2014, 1 497 newly diagnosed ALL patients were enrolled and treated in 5 hospitals of SCMC-ALL-2005 study group, using risk-stratified SCMC-ALL-2005 protocol. Risk group classification and treatment intensity were based on clinical features, genetic abnormalities, early response to treatment and levels of minimal residual disease (MRD). Kaplan-Meier method was used to generate overall survival (OS) and event-free survival(EFS) curves. Cox proportional hazards models were used for multivariate analyses. Results: The patients were followed up to December 31, 2016, the median follow-up time was 69 months (24-141 months). The 5-year and 10-year OS rates were (80.0±1.0)% and (76.0±2.0)%. The 5-year and 10-year EFS rates were (69.0±1.0)% and (66.0±2.0)%. The 5-year and 10-year relapse rates were (23.0±1.0)% and (25.0±2.0)%. The 5-year OS and EFS for low risk (LR), intermediate risk (IR) and high risk (HR) were (91.1±1.4)% and (83.3±1.8)%, (79.2±1.5)% and (68.9±1.7)%, (52.9±4.4)% and (30.0±3.8)%, respectively. MRD negative status (<0.01%) on day 55 was seen in 792 patients (82.8%) and positive MRD on day 55 was associated with poor prognosis (OR=1.9, 95%CI: 1.3-2.7, P=0.001). Twenty-four HR patients received allogeneic hematopoietic stem cell transplantation and 17(70.8%) of them were alive and in remission. A total of 164 severe adverse events occurred, 46 of them died, treatment-related mortality was 3.1%. Conclusions: In this large sample research, the overall outcome for multi-center SCMC-ALL-2005 study was favorable. This helps to promote the standardized treatment of childhood ALL to the whole country. MRD results on day 55 of induction therapy have important prognostic and therapeutic implications.

[Outcome of childhood T-cell acute lymphoblastic leukemia: a report of 99 cases]

OBJECTIVE

To explore the incidence, clinical characteristics and prognosis of childhood T-cell acute lymphoblastic leukemia (T-ALL) enrolled in protocol ALL-2005.

METHOD

Retrospective reviews of patients diagnosed as having T-ALL were studied in the period between May 2005 and August 2013 in Shanghai Children's Medical Center. Predictive values of early treatment responses, including prednisone response, bone marrow morphology on day 35 during induction chemotherapy, and minimal residual disease (MRD) monitored by flow cytometry on day 35 and 55, were analyzed. The Kaplan-Meier method was used to assess the survival rates.

RESULT

Ninety-nine evaluable patients aged 1-18 years with newly diagnosed T-ALL were enrolled in protocol ALL-2005. The median follow-up period for patients remaining alive in continuous remission was 60 months (24-109 months). The 5-year event free survival (EFS) and overall survival (OS) rates for these patients were 65% and 69%, respectively. Forty-three (43%) patients were older than 10 years at diagnosis. A total of 61 patients presented with initial white blood cell count (WBC)≥50×10(9)/L. Thirty-seven patients with mediastinal mass were found in this study. Seventy-one patients were defined as prednisone good responders (PGR) on day 8 of prednisone therapy. Ninty-four patients achieved complete remission (CR) on day 35 of induction therapy. MRD negative status (<0.01%) on day 35 were seen in 55% of the 42 assessed patients. MRD negative status on day 55 was seen in 78% of the 52 assessed patients. Patients with high MRD (>1%) on day 55 5-year EFS was 40% were associated with poor prognosis (P=0.03). Early T-cell precursor (ETP) subtype was not associated with treatment outcome in this study. Six patients abandoned therapy, 10 lost to follow-up, 22 had relapsed disease, 1 was diagnosed as having a second tumor and 20 patients died.

CONCLUSION

Overall outcome for T-ALL on protocol ALL-2005 is favorable. MRD results on day 55 of induction therapy have important prognostic and therapeutic implications.

Whole-body positron emission tomography with 18F-fluorodeoxyglucose is an effective method to detect extra-pelvic recurrence in uterine sarcomas

PURPOSE OF INVESTIGATION

To assess the clinical use of F-18-fluorodeoxyglucose positron emission tomography (FDG-PET) in the post-therapy surveillance of uterine sarcoma.

METHODS

Eight whole-body FDG-PET studies were performed in seven women with previously treated uterine sarcoma. Conventional image studies (computed tomography) and physical examinations were performed for follow-up. All FDG-PET studies were indicated to localize suspected recurrences noted by conventional methods.

RESULTS

The per case sensitivity of the FDG-PET studies and CT scans was 85.7% (6/7) and 100% (7/7), respectively (p = 0.174). FDG-PET was able to detect seven extrapelvic metastastic sites below the diaphragm (7/7, sensitivity: 100%), including the liver, spleen, paraaortic lymph node, spine and paracolic gutter, as well as pulmonary lesions in five patients, while the CT scan detected only three lesions (3/7, sensitivity: 42.9%; p = 0.070). FDG-PET detected only four recurrent pelvic lesions (4/6) and CT scan detected six (6/6) recurrent pelvic lesions (66.7% vs 100%, p = 0.455).

CONCLUSIONS

The FDG-PET showed a better detection rate than the abdominal CT scan for extrapelvic metastatic lesions and a similar detection rate as well as abdominal CT scan. FDG-PET can serve as a useful detection tool for patients with uterine sarcomas because nearly 80% of recurrence involve an extrapelvic site.

Experimental change on dopaminergic neurons in striatum of Parkinson disease rats

BACKGROUND

Parkinson's disease (PD) is a common neurodegenerative disorder characterized by selective and progressive demise of dopamine-containing neurons in the midbrain. In this study, we observe the expression of c-Jun in the striatum of rats with 6-hydroxydopamine (6-OHDA)-lesions after apomorphine (APO) intraperitoneal injection (ip) in substantia nigra compacta (SNc), and to study the mechanism of the rotations behavior.

DESIGN

The 6-OHDA was unilaterally injected into rat right SNC. The APO- induced abnormal rotations were investigated on the 1st, 4th, 7th, 14th, 21st days after lesion, respectively. Meanwhile dopaminergic degeneration and c-Jun expression were observed with microscope. Nissl's body staining and immunohistochemical method (ABC) were employed to study the changes of tyrosine hydroxylase (TH) and c-Jun in DA neurons.

RESULTS

We found that the number of dopaminergic neurons decreased gradually in the lesioned site and those neurons' electron-microscopic structure was severe damaged. There were over 75% of dopaminergic neurons lost, contralateral rotations over 7 turns per minute and c-Jun expressing in the ipsilateral striatum.

CONCLUSION

Dopaminergic neurons deletion may be linked to upregulation of c-Jun.

Proenkephalin A gene products activate a new family of sensory neuron--specific GPCRs

Several peptide fragments are produced by proteolytic cleavage of the opioid peptide precursor proenkephalin A, and among these are a number of enkephalin fragments, in particular bovine adrenal medulla peptide 22 (BAM22). These peptide products have been implicated in diverse biological functions, including analgesia. We have cloned a newly identified family of 'orphan' G protein--coupled receptors (GPCRs) and demonstrate that BAM22 and a number of its fragments bind to and activate these receptors with nanomolar affinities. This family of GPCRs is uniquely localized in the human and rat small sensory neuron, and we called this family the sensory neuron--specific G protein--coupled receptors (SNSRs). Receptors of the SNSR family are distinct from the traditional opioid receptors in their insensitivity to the classical opioid antagonist naloxone and poor activation by opioid ligands. The unique localization of SNSRs and their activation by proenkephalin A peptide fragments indicate a possible function for SNSRs in sensory neuron regulation and in the modulation of nociception.

Primary leiomyosarcoma of bone

We report a case of primary leiomyosarcoma in the right femoral diaphysis. Conventional radiographs revealed an indistinct osteolytic lesion with a very subtle periosteal reaction. MR imaging revealed an intramedullary lesion with a well-defined margin, cortical breakthrough and soft tissue extension. The lesion was isointense relative to muscle on T1-weighted imaging, iso-hypointense relative to fat on fast spin echo T2-weighted imaging, and hyperintense to muscle on fast spin echo T2-weighted imaging with fat saturation. A peripheral rim and intratumoral spoke-wheel-like enhancement in the soft tissue component of the tumor was noted on gadolinium-enhanced T1-weighted imaging with fat saturation. Such an enhancing pattern, which has not been described in the literature previously but has been seen in leiomyosarcomas elsewhere by both MR imaging and computed tomography, deserves further pathological correlation.

Identification and characterization of S2V, a novel putative siglec that contains two V set Ig-like domains and recruits protein-tyrosine phosphatases SHPs

We describe the molecular cloning and characterization of S2V, a novel sialic acid binding immunoglobulin-like lectin. The cDNA of S2V encodes a type 1 transmembrane protein with four extracellular immunoglobulin-like (Ig-like) domains and a cytoplasmic tail bearing a typical immunoreceptor tyrosine-based inhibitory motif (ITIM) and an ITIM-like motif. A unique feature of S2V is the presence of two V-set Ig-like domains responsible for the binding to sialic acid, whereas all other known siglecs possess only one. S2V is predominantly expressed in macrophage. In vivo S2V was tyrosine-phosphorylated when co-expressed with exogenous c-Src kinase. Upon tyrosine phosphorylation, S2V recruits both Src homology 2 (SH2) domain-containing protein-tyrosine phosphatases SHP-1 and SHP-2, two important inhibitory regulators of immunoreceptor signal transduction. These findings suggest that S2V is involved in the negative regulation of the signaling in macrophage by functioning as an inhibitory receptor. When expressed in COS-7 cells, S2V was able to mediate sialic acid-dependent binding to human red blood cells, suggesting that S2V may function through cell-cell interaction.

Magnetic resonance imaging appearance of intradural spinal lipoma

Intradural spinal lipoma not associated with spinal dysraphism is a rare tumor often presenting with nonspecific symptoms and indolent clinical course. Its intradural location and fat component is the key for proper preoperative diagnosis, which could hardly be made by traditional imaging studies including plain film and myelography. Both CT and MRI can reveal the fat component of the tumor, but MRI is superior to CT in demonstrating its relationship with adjacent normal nerve tissue. We report a 32-year-old man who had back pain for years and the symptom progressed rapidly in recent two months. MRI revealed an intradural tumor at T12 level with high signal intensity on both T1- and T2-weighted images. The signal intensity dropped dramatically with fat saturation technique, which confirmed fat as its main component. The patient received surgery and the tumor was proved to be an intraspinal lipoma.

Use of pulsed-field gel electrophoresis to investigate an outbreak of Serratia marcescens infection in a neonatal intensive care unit

Serratia marcescens is a well-recognized hospital-acquired pathogen, which has been associated with a number of specific outbreaks, particularly in critically ill neonates. We used pulsed-field gel electrophoresis (PEGE) typing to analyse an outbreak in a neonatal intensive care unit (NICU). We included samples from nine patients, three handwashes and ten environmental isolates from an outbreak (February to August 1999) in addition to four patient isolates from different wards of our hospital during the same time period. The clinical presentations of the outbreak included bacteraemia (four cases), pneumonia (three cases), umbilical wound infection (one case) and conjunctivitis (one case). Nine outbreak isolates exhibited an identical PFGE fingerprint, while the epidemiologically unrelated strains demonstrated distinct patterns. Epidemiological investigation failed to reveal a common source of the outbreak, although the epidemic S. marcescens strain was isolated from hand-washes and doors of incubators. We concluded that cross-transmission via transient contamination of hands was the major route for this outbreak. Strict handwashing practices, the cohorting and isolation of colonized and infected patients, and the regular dis-infection of incubators are crucial steps for preventing the transmission of S. marcescens in an NICU. This PFGE method is highly discriminatory for the thorough epidemiological investigation of an outbreak of S. marcescens.

Transcriptional activity of the SHP-1 gene in MCF7 cells is differentially regulated by binding of NF-Y factor to two distinct CCAAT-elements

Our previous studies have shown that SHP-1, a SH2 domain-containing protein-tyrosine phosphatase, is expressed not only in cells of hematopoietic lineages, but also in many non-hematopoietic cells under the control of an alternative tissue-specific promoter, P1. In this study, the activity of the P1 promoter was analyzed in a region spanning 3.5 kb upstream of the major transcription start site in non-hematopoietic MCF-7 cells. Using DNA footprinting, gel retardation assays and mutational analysis, we have characterized cis-regulatory elements that are essential to confer the P1 promoter activity. An upstream Sp1 element (-126 to -118) positively regulated this TATA-box-lacking promoter. Two inverted CCAAT-elements (-332 to -328 and -66 to -62) played important roles in regulating the SHP-1 gene expression, and transcription factor NF-Y predominantly bound to the two CCAAT-elements. Binding of NF-Y to the distal CCAAT-element enhanced the transcriptional activity of the P1 promoter. In contrast, binding of NF-Y to the proximal CCAAT-element and interacting with repressor(s) inhibited the promoter activity. Furthermore, incubation of MCF7 cells with 100 ng/ml trichostatin A, an inhibitor of histone deacetylase, significantly increased the activity of the P1 promoter. Mutation in the proximal CCAAT-element, however, eliminated the activating effect of trichostatin A on the promoter. Together, our data suggest that NF-Y factor can function either as a specific positive or negative regulator of P1 promoter activity in non-hematopoietic MCF7 cells.

Tissue characterization and calcification potential of commercial bioprosthetic heart valves

BACKGROUND

Tissue properties may contribute to intrinsic calcification of bioprosthetic heart valves. Phospholipids have been proposed as potential nucleation sites for calcification. Other tissue properties might also be important in calcification.

METHODS

Commercial and control bioprosthetic valve tissues were characterized by shrinkage temperature, moisture content, free amine content, phospholipid content, and calcification level after 90-day rat subcutaneous implantation as described.

RESULTS

Shrinkage temperature, moisture content, and free amine content were typical for glutaraldehyde-cross-linked tissues. Phospholipid and calcium levels varied considerably among valve types. There was a significant correlation between phospholipid levels and calcification (r = 0.63, p = 0.04). Sulzer Carbomedics Mitroflow and Toronto SPV valve tissues had significantly more calcification than other commercial bioprostheses in this study (p < 0.01). Carpentier-Edwards Duraflex, CE SAV, and CE PERIMOUNT valve tissues had significantly less calcification than Medtronic Mosaic in this animal model (p < 0.02).

CONCLUSIONS

Processes that reduce phospholipid levels are associated with reduced calcification in the rat subcutaneous model. Significant differences in calcification level were found among commercially available valves. The clinical significance of these results is unknown.

Ontogenic profile of the expression of the mu opioid receptor gene in the rat telencephalon and diencephalon: an in situ hybridization study

The developmental profile of mu (mu) opioid receptor gene expression has been characterized in the embryonic, postnatal and adult rat brain by in situ hybridization histochemistry. By ED12, mu opioid receptor mRNA was detectable in the deep neuroepithelium of the cortical plate. In the developing rat central nervous system (ED13-PD40), transcripts were seen over numerous telencephalic and diencephalic structures, such as the olfactory bulb, caudate-putamen, nucleus accumbens, amygdaloid complex, hippocampal formation, hypothalamus and thalamus. In the vast majority of brain regions examined, the developmental profile of the mu opioid receptor gene expression is similar to that of its translated protein as established using receptor autoradiography. Once a hybridization signal is detected in the prenatal period, it gradually increased to reach maximal levels during the second and third postnatal weeks. By the end of the third postnatal week, mu opioid receptor mRNA levels decreased to reach amounts seen in adulthood. Our study demonstrates that mu opioid receptor gene expression is seen very early on in the embryonic rat brain with transient increases observed during the critical period of neurogenesis, neuronal migration and synaptogenesis, suggesting a role of this opioid receptor subtype in brain developmental processes.

Caspase-8-mediated intracellular acidification precedes mitochondrial dysfunction in somatostatin-induced apoptosis

Activation of initiator and effector caspases, mitochondrial changes involving a reduction in its membrane potential and release of cytochrome c (cyt c) into the cytosol, are characteristic features of apoptosis. These changes are associated with cell acidification in some models of apoptosis. The hierarchical relationship between these events has, however, not been deciphered. We have shown that somatostatin (SST), acting via the Src homology 2 bearing tyrosine phosphatase SHP-1, exerts cytotoxic action in MCF-7 cells, and triggers cell acidification and apoptosis. We investigated the temporal sequence of apoptotic events linking caspase activation, acidification, and mitochondrial dysfunction in this system and report here that (i) SHP-1-mediated caspase-8 activation is required for SST-induced decrease in pH(i). (ii) Effector caspases are induced only when there is concomitant acidification. (iii) Decrease in pH(i) is necessary to induce reduction in mitochondrial membrane potential, cyt c release and caspase-9 activation and (iv) depletion of ATP ablates SST-induced cyt c release and caspase-9 activation, but not its ability to induce effector caspases and apoptosis. These data reveal that SHP-1-/caspase-8-mediated acidification occurs at a site other than the mitochondrion and that SST-induced apoptosis is not dependent on disruption of mitochondrial function and caspase-9 activation.

PILRalpha, a novel immunoreceptor tyrosine-based inhibitory motif-bearing protein, recruits SHP-1 upon tyrosine phosphorylation and is paired with the truncated counterpart PILRbeta

SHP-1-mediated dephosphorylation of protein tyrosine residues is central to the regulation of several cell signaling pathways, the specificity of which is dictated by the intrinsic affinity of SH2 domains for the flanking sequences of phosphotyrosine residues. By using a modified yeast two-hybrid system and SHP-1 as bait, we have cloned a human cDNA, PILRalpha, encoding a 303-amino acid immunoglobulin-like transmembrane receptor bearing two cytoplasmic tyrosines positioned within an immunoreceptor tyrosine-based inhibitory motif. Substrate trapping in combination with pervanadate treatment of 293T cells confirms that PILRalpha associates with SHP-1 in vivo upon tyrosine phosphorylation. Mutation of the tyrosine residues in PILRalpha indicates the pivotal role of the Tyr-269 residue in recruiting SHP-1. Surface plasmon resonance analysis further suggests that the association between PILRalpha-Tyr-269 and SHP-1 is mediated primarily via the amino-terminal SH2 domain of the latter. Polymerase chain reaction amplification of cDNA in combination with genomic sequence analysis revealed a second gene, PILRbeta, coding for a putative activating receptor as suggested by a truncated cytoplasmic tail and a charged lysine residue in its transmembrane region. The PILRalpha and PILRbeta genes are localized to chromosome 7 which is in contrast with the mapping of known members of the inhibitory receptor superfamily.

Regulation of acidification and apoptosis by SHP-1 and Bcl-2

Recruitment of the SH2 domain containing cytoplasmic protein-tyrosine phosphatase SHP-1 to the membrane by somatostatin (SST) is an early event in its antiproliferative signaling that induces intracellular acidification-dependent apoptosis in breast cancer cells. Fas ligation also induces acidification-dependent apoptosis in a manner requiring the presence of SHP-1 at the membrane. Moreover, we have recently reported that SHP-1 is required not only for acidification, but also for apoptotic events that follow acidification (Thangaraju, M., Sharma, K., Liu, D., Shen, S. H., and Srikant, C. B. (1999) Cancer Res. 59, 1649-1654). Here we show that ectopically expressed SHP-1 was predominantly membrane-associated and amplified the cytotoxic signaling initiated upon SST receptor activation and Fas ligation. The catalytically inactive mutant of SHP-1 (SHP-1C455S) abolished the ability of the SST agonists to signal apoptosis by preventing the recruitment of wild type SHP-1 to the membrane. Overexpression of the anti-apoptotic protein Bcl-2 in MCF-7 cells inhibited SST-induced apoptosis upstream of acidification by inhibiting p53-dependent induction of Bax as well as by raising the resting pH(i) and attenuating SST-induced decrease in pH(i). By contrast, Bcl-2 failed to prevent apoptosis triggered by direct acidification. These data demonstrate that (i) membrane-associated SHP-1 is required for receptor-mediated cytotoxic signaling that causes intracellular acidification and apoptosis, and (ii) Bcl-2 acts distal to SHP-1 and p53 to prevent SST-induced acidification but cannot inhibit the apoptotic events that ensue intracellular acidification.

Induction of humoral and cellular immune responses against the nucleocapsid of bovine viral diarrhea virus by an adenovirus vector with an inducible promoter

A new recombinant adenovirus was constructed that expressed the nucleocapsid (C protein or p14) of the bovine viral diarrhea virus (BVDV) under the control of a tetracycline-regulatable promoter. Mice covaccinated with this recombinant adenovirus, accompanied by another recombinant adenovirus expressing the trans-activator protein, induced a strong humoral immune response to the BVDV/C protein as detected by ELISA. Splenocytes from mice immunized with the recombinant adenovirus showed a specific proliferation response to both genotypes (type 1 and 2) of BVDV. High levels of IFN-gamma were detected in the supernatant of murine mononuclear cells of mice immunized by the recombinant adenovirus when stimulated in vitro by both genotypes of BVDV. These results indicate that this recombinant adenovirus is highly immunogenic and stimulates both cellular and humoral immune responses against the nucleocapsid of BVDV.

Investigation of the immunological properties of the bovine viral diarrhea virus protein NS3 expressed by an adenovirus vector in mice

Two replication-defective human adenovirus recombinants encoding the NS3 protein (p80) of bovine viral diarrhea virus (BVDV) under the control of a modified adenovirus major later promoter (BM5), rAdBM5/NS3, and human cytomegalovirus promoter (CMV5), rAdCMV5/NS3, were constructed. These two recombinant adenoviruses were tested for their expression of the NS3 protein in vitro in three different cell lines and also in vivo for the induction of BVDV-specific immune responses in mice. The recombinant adenoviruses containing two different promoters induced different levels of humoral responses to the NS3 protein. The rAdBM5/NS3 was used to vaccinate mice in order to evaluate the ability of the NS3 protein in the induction of cellular immune responses. The rAdBM5/NS3 did not cause a stimulation of cell proliferation but caused a very strong increase in production of IFN-gamma in murine mononuclear cells stimulated in vivo by BVDV strains of genotype 1 and 2.

Recombinant adenoviruses expressing the E2 protein of bovine viral diarrhea virus induce humoral and cellular immune responses

The E2 protein of bovine viral diarrhea virus (BVDV) is a major viral glycoprotein and an attractive target for BVDV vaccines. Three replication defective recombinant adenoviruses expressing the BVDV/E2 protein (rAds/E2) were constructed. Two contain a constitutive promoter, and one an inducible promoter. All three recombinant adenoviruses induced very strong BVDV specific antibody responses in a mouse model as detected by enzyme-linked immunosorbant assay (ELISA) and neutralization tests. Induction of cellular immune responses was investigated in two recombinant adenoviruses with a constitutive promoter. The mononuclear cells from the immunized mice demonstrated a proliferative response after in vitro stimulation with an homologous BVDV strain, but only one of them induced the production of IFN-gamma.

ZRP-1, a zyxin-related protein, interacts with the second PDZ domain of the cytosolic protein tyrosine phosphatase hPTP1E

Protein-protein interactions play an important role in the specificity of cellular signaling cascades. By using the yeast two-hybrid system, a specific interaction was identified between the second PDZ domain of the cytosolic protein tyrosine phosphatase hPTP1E and a novel protein, which was termed ZRP-1 to indicate its sequence similarity to the Zyxin protein family. The mRNA encoding this protein is distributed widely in human tissues and contains an open reading frame of 1428 base pairs, predicting a polypeptide of 476 amino acid residues. The deduced protein displays a proline-rich amino-terminal region and three double zinc finger LIM domains at its carboxyl terminus. The specific interaction of this novel protein with the second PDZ domain of hPTP1E was demonstrated both in vitro, using bacterially expressed proteins, and in vivo, by co-immunoprecipitation studies. Deletion analysis indicated that an intact carboxyl terminus is required for its interaction with the second PDZ domain of hPTP1E in the yeast two-hybrid system and suggested that other sequences, including the LIM domains, also participate in the interaction. The genomic organization of the ZRP-1 coding sequence is identical to that of the lipoma preferred partner gene, another Zyxin-related protein, suggesting that the two genes have evolved from a recent gene duplication event.

Nosocomial gram-negative bacteremia in critically ill patients: epidemiologic characteristics and prognostic factors in 147 episodes

Although gram-positive organisms are the most common causes of nosocomial bloodstream infections, gram-negative bacteremia carries higher risks of severe sepsis, septic shock, and death among critically ill patients in intensive care units (ICUs). We performed a prospective epidemiologic analysis of nosocomial gram-negative bacteremia episodes among ICU patients and sought to identify risk factors for mortality among these patients. All episodes of nosocomial gram-negative bacteremia documented in five ICU wards of our hospital during a 2-year period were included. There were 147 episodes (124 patients) of gram-negative bacteremia documented during the study period. The overall mortality rate was 36.1%, and 77.4% of all deaths were directly related to the bloodstream infection. Gram-negative bacteremia was associated with prolonged ICU stay (45.7 d vs 6.1 d for all ICU patients). The most common isolate was Acinetobacter baumannii, followed by Burkholderia cepacia and Enterobacter cloacae. The most frequent source of infection was the lower respiratory tract (32.0%). Of the agents tested, ciprofloxacin, imipenem, and ceftazidime were the most active against the clinical isolates. Multivariate logistic regression analysis identified the presence of septic shock (odds ratio, OR = 17.66, p < 0.001) and rapidly fatal and ultimately fatal underlying conditions (OR = 3.47, p = 0.032) as being independent risk factors for mortality. Early appropriate antibiotic treatment did not result in significant improvement in survival. These findings suggest that prevention of lower respiratory tract colonization and nosocomial pneumonia are crucial for reducing the incidence of nosocomial gram-negative bacteremia in the ICU. Serious underlying illnesses and septic shock were the most important risk factors for death in these patients.

Characterization of a polyepoxy compound fixed porcine heart valve bioprosthesis

Concerns with the currently available bioprostheses are calcification, long-term durability, and suboptimal hemodynamic performance. It is well known that these concerns are all more or less related to the cross-linking reagent, glutaraldehyde or formaldehyde, used in fixing bioprostheses. To address these concerns, we undertook the development of a porcine bioprosthesis fixed with a polyepoxy compound. In the development of this polyepoxy compound valve, it was found that the porcine leaflets fixed with polyepoxy compound were softer and more pliable than those fixed with glutaraldehyde. In this study, a special microtoming technique was developed to section the biological tissue so that the fixation uniformity in distinct layers of porcine aortic wall could be characterized. The fixation index and the denaturation temperature measurements in distinct layers of aortic walls showed that the cross-linking density was uniform throughout the entire aortic wall for the polyepoxy compound fixed porcine valve. It was also noted that the fixation index of the polyepoxy compound fixed aortic wall (91.5 +/- 0.5, n = 3) was not significantly different from that of its valvular leaflet (90.6 +/- 0.8, n = 3). Similarly, the denaturation temperature of the polyepoxy compound fixed aortic wall (80.4 +/- 0.9 degrees C, n = 5) was statistically comparable to that of its valvular leaflet (79.0 +/- 0.5 degrees C, n = 5). The results of this study indicated that polyepoxy compound can adequately fix the entire porcine aortic wall as well as its valvular leaflets.(ABSTRACT TRUNCATED AT 250 WORDS)

Interdependent regulation of intracellular acidification and SHP-1 in apoptosis

The G protein-coupled receptor agonist somatostatin (SST)-induces apoptosis in MCF-7 human breast cancer cells. This is associated with induction of wild-type p53, Bax, and an acidic endonuclease. We have shown recently that its cytotoxic signaling is mediated via membrane-associated SHP-1 and is dependent on decrease in intracellular pH (pHi) to 6.5. Here we investigated the relationship between intracellular acidification and SHP-1 in cytotoxic signaling. Clamping of pHi at 7.25 by the proton-ionophore nigericin abolished SST-signaled apoptosis without affecting its ability to regulate SHP-1, p53, and Bax. Apoptosis could be induced by nigericin clamping of pHi to 6.5. Such acidification-induced apoptosis was not observed at pHi <6.0 or >6.7. pHi-dependent apoptosis was associated with the translocation of SHP-1 to the membrane, enhanced in cells overexpressing SHP-1, and was abolished by its inactive mutant SHP-1C455S. Acidification caused by inhibition of Na+/H+ exchanger and H+ ATPase (pHi = 6.55 and 6.65, respectively) also triggered apoptosis. The effect of concurrent inhibition of Na+/H+ exchanger and H(+)-ATPase on pHi and apoptosis was comparable with that of SST. Acidification-induced, SHP-1-dependent apoptosis occurred in breast cancer cell lines in which SST was cytotoxic (MCF-7 and T47D) or not (MDA-MB-231). We conclude that: (a) SST-induced SHP-1-dependent acidification occurs subsequent to or independent of the induction of p53 and Bax; (b) SST-induced intracellular acidification may arise due to inhibition of Na+/H+ exchanger and H(+)-ATPase; and (c) SHP-1 is necessary not only for agonist-induced acidification but also for the execution of acidification-dependent apoptosis. We suggest that combined targeting of SHP-1 and intracellular acidification may lead to a novel strategy of anticancer therapy bypassing the need for receptor-mediated signaling.

Induction of humoral and cellular immune responses in mice by a recombinant fowlpox virus expressing the E2 protein of bovine viral diarrhea virus

A recombinant fowlpox virus (rFPV/E2) expressing the E2 protein of bovine viral diarrhea virus (BVDV) was constructed and characterized. Mice were immunized with recombinant virus and both humoral and cellular immune responses were studied. rFPV/E2 induced BVDV-specific antibodies which were detected by ELISA. In addition, mouse sera were shown to neutralize BVDV. A cytokine ELISA assay revealed that mice vaccinated with rFPV/E2 induced 7-fold more interferon-gamma than parental fowlpox virus.

Effect of peptide binding on amide proton exchange rates in the PDZ2 domain from human phosphatase hPTP1E

Amide hydrogen-deuterium exchange rates were measured in the PDZ2 domain from human phosphatase hPTPIE by 1H-15N heteronuclear NMR spectroscopy. Protection factors were calculated for the slowly exchanging hydrogens in both the free PDZ2 domain and its complex with an octapeptide peptide, R-N-E-I-Q-S-L-V, derived from the C-terminus of the Fas receptor. Aside from a short alpha-helical region alpha1 (amino acids A-45 to D-49), the pattern of highly protected amides correlated well with the presence of hydrogen bonds in elements of the secondary structure. Hydrogen-bonded amides showed relatively fast exchange rates with half-lives of less than 9 h at pD 7.6 and 8 degrees C. Protection factors, calculated as the ratio of theoretical (denatured) and observed exchange rates, showed less dispersion in maximal values than did the actual exchange rates. This behavior and the large pH dependence of the exchange rates suggest that amide exchange is close to the EX2 limit. In this limit, exchange of the most protected amides occurs through a global unfolding mechanism. The free energy of the unfolding calculated from the largest protection factors is 4.8 +/- 0.4 kcal/mol (1 cal = 4.184 J). This deltaG(o) closely matches the value measured by experiments with guanidine hydrochloride and fluorescence emission spectroscopy. Peptide binding to PDZ2 resulted in mostly global effects and stabilized the folded domain by 1.4 kcal/mol.

Fusion proteins could generate false positives in peptide phage display

Fusion proteins are frequently used in the functional characterization of newly discovered proteins and to identify interacting partners. In our study of hPTP1E, a cytosolic protein tyrosine phosphatase, we used glutathione S-transferase (GST)-fusion protein of the second PDZ domain to identify interacting peptide motifs by peptide phage display. A consensus motif G X X V W L G was identified and found to be specific for binding to GST-PDZ2 as determined by ELISA, peptide displacement and by protein overlay. However, using nuclear magnetic resonance (NMR), no interaction of the peptide was observed with PDZ2 alone. In co-precipitation experiments using the consensus peptide cross-linked to Affi-Gel, only GST-PDZ2 (but not PDZ2 or GST alone) could be precipitated. These data suggest that there is a potential for identification of artifacts when using fusion proteins in peptide phage display, and one should exercise caution in interpreting these results. It is critical that the interaction be verified using a second, independent system.

Cloning and characterization of a novel mammalian PP2C isozyme

PP2C is a structurally diversified protein phosphatase family with a wide range of functions in cellular signal transduction. A novel PP2C subtype, designated PP2Cdelta, was identified from a rat cDNA clone, which encodes a protein of 392 amino acid residues. While PP2Cdelta shares approximately 30% sequence identity in its catalytic domain with the mammalian PP2C, it lacks a 90-residue carboxyl-terminal sequence conserved in mammalian PP2C. Northern blot analysis showed that PP2Cdelta is widely expressed in rat tissues. The transcription of the PP2Cdelta gene was activated in response to stress, such as the addition of ethanol to the culture medium or UV irradiation of cells. Recombinant PP2Cdelta purified from bacteria exhibited a potent Mn2+-dependent serine/threonine phosphatase activity. Unlike other members of the PP2C family, the activity of PP2Cdelta was inhibited, rather than stimulated, by Mg2+. Transfection with PP2Cdelta resulted in inhibition of cell growth, precluding generation of stable 293 or CHO transfectants. Using a modified tetracycline-regulated PP2Cdelta-GFP dicistronic expression cassette, it was revealed that overexpression of PP2Cdelta blocked cell cycle progression and arrested cells at early S phase, resulting in inhibition of DNA synthesis and leading to cell death. These results suggest that PP2Cdelta plays a role in regulation of cell cycle progression via dephosphorylation of its substrates whose appropriate phosphorylation states might be crucial for cell proliferation.

Cloning and evaluation of the role of rat GALR-2, a novel subtype of galanin receptor, in the control of pain perception

We have identified a novel subtype of galanin receptor (GALR-2) in rat dorsal root ganglia and spinal cord. The open reading frame of GALR-2 is 1116 nucleotides long, encoding a protein of 372 amino acids with a theoretical molecular mass of 40.7 kD. Membranes prepared from stable pools of 293 cells expressing GALR-2, but not wild-type 293 cells, demonstrated high affinity galanin binding sites. Rat galanin and galanin-related peptides M40, C7, M15, and galanin effectively competed for binding; peptide C7 demonstrated a lower affinity for rGALR-2, and all these peptides were agonists at rGALR-2 when assessed on a microphysiometer. Studies on the expression of GALR-2 in various tissues by Northern and in situ hybridization analyses suggest a low abundance but wide distribution of GALR-2 mRNA, including several discrete areas in brain and spinal cord and a high abundance in the dorsal root ganglia.

Discrete distribution of the neuropeptide Y Y5 receptor gene in the human brain: an in situ hybridization study

The present study investigated the regional distribution of putative 'food-intake'-related neuropeptide Y Y5 receptor gene using cRNA in situ hybridization in various regions of the normal control post-mortem human brain. Interestingly, significant levels of Y5 receptor expression were detected in the hypothalamus; the arcuate nucleus being particularly enriched compared to other hypothalamic nuclei. Surprisingly, strong hybridization signals were also noted in the stratum granulosum of the dentate gyrus contrasting with lower levels of Y5 receptor transcripts in other regions of the hippocampal formation. The cerebral cortex, basal ganglia and thalamus were not enriched with Y5 receptor mRNA. It thus appears that the expression of the Y5 receptor gene in the human brain is rather restricted with enrichment in areas consistent with the involvement of this receptor type in the modulation of appetite and seizures.

Epitope mapping of SHP-1 monoclonal antibodies using peptide phage display

We have characterized the binding epitopes of four monoclonal antibodies for SHP-1, an SH2 domain containing protein tyrosine phosphatase, using two phage displayed random peptide libraries. Three of the antibodies are directed against the phosphatase domain of the molecule and the fourth is toward the NH2-terminal part of the second SH2 domain. The first two antibodies recognize the sequence NANY, amino acid 305 to amino acid 308, numbered in the non haematopoietic form of human SHP-1 sequence. The third antibody binds the sequence P Y W P (amino acids 365 to 368) located toward the middle of the phosphatase domain of the enzyme. The fourth antibody is directed against the first two amino acids, W Y (amino acids 112 and 113), of the second SH2 domain. The specificities of these antibodies are demonstrated by ELISA and western blot using different protein constructs expressed in bacteria. All the antibodies can detect wild type SHP-1, expressed in 293 cells, by western blot analysis, both under denaturing conditions as well as following renaturation. The data presented here show that the antibodies characterized in this study are raised against linear epitopes and suggest that these epitopes are accessible from the outside in the native SHP-1 molecule.

Evaluation of in vivo models for studying calcification behavior of commercially available bovine pericardium

BACKGROUND AND AIM OF THE STUDY

A common frame of reference is essential when attempting to determine if new treatments intended to reduce calcification of bioprostheses are superior to existing processes and products. The aim of this study was to examine calcification behavior for a commercially available pericardial bioprosthesis in subcutaneous and sheep valve models, and to evaluate the importance of appropriate control treatments in comparative studies with proposed new treatments.

METHODS

Samples of bovine pericardium were placed subcutaneously under the dorsal skin of weanling rats and juvenile rabbits for 30-, 60- and 90-day intervals. Samples were either commercially available pericardial tissue or tissue processed with phosphate-buffered glutaraldehyde alone. Commercially available pericardial valves were also implanted in the mitral position in juvenile sheep, with elective sacrifice at 20 weeks. Retrieved samples underwent X-ray, histologic and elemental analysis.

RESULTS

Commercial samples retrieved from the subcutaneous and sheep models showed similar, minimal calcification behavior on X-ray and histologic slides, whereas pericardium exposed to glutaraldehyde alone demonstrated rapid calcification.

CONCLUSIONS

The 90-day subcutaneous rabbit model produced patterns of calcification similar to those in valves explanted from juvenile sheep after 20 weeks. A statistically significant decrease (p < 10(-8)) in calcification was demonstrated for clinical pericardium when compared with pericardium exposed to glutaraldehyde alone in the subcutaneous model. This suggests that subcutaneous models may be a cost-effective, time-efficient means of evaluating and comparing various tissue treatment methods. The rabbit methodology may provide a more accurate prediction of clinical performance, offering a greater degree of sensitivity. These studies also indicate that the commercially available process shows minimal calcification in the commonly used 30-day weanling rat subcutaneous model, contradicting other reported studies that may not accurately represent commercially available processes.

SHP-1 associates with both platelet-derived growth factor receptor and the p85 subunit of phosphatidylinositol 3-kinase

The Src homology 2 (SH2)-containing protein tyrosine phosphatase 1, SHP-1, is highly expressed in all hematopoietic cells as well as in many non-hematopoietic cells, particularly in some malignant epithelial cell lines. In hematopoietic cells, SHP-1 negatively regulates multiple cytokine receptor pathways. The precise function and the targets of SHP-1 in non-hematopoietic cells, however, are largely unknown. Here we demonstrate that SHP-1 associates with both the tyrosine-phosphorylated platelet-derived growth factor (PDGF) receptor and the p85 subunit of phosphatidylinositol 3-kinase in MCF-7 and TRMP cells. Through the use of mutant PDGF receptors and performing peptide competition for immunoprecipitation, it was determined that SHP-1 independently associates with the PDGF receptor and p85 and that its N-terminal SH2 domain is directly responsible for the interactions. Overexpression of SHP-1 in TRMP cells transfected with the PDGF receptor markedly inhibited PDGF-induced c-fos promoter activation, whereas the expression of three catalytically inactive SHP-1 mutants increased the c-fos promoter activation in response to PDGF stimulation. These results indicate that SHP-1 might negatively regulate PDGF receptor-mediated signaling in these cells. Identification of the association of SHP-1 with the PDGF receptor and p85 in MCF-7 and TRMP cells furthers our understanding of the function of SHP-1 in non-hematopoietic cells.

Comparative developmental profile of the neuropeptide Y Y1 receptor gene and protein in the rat brain

Neuropeptide Y (NPY) is one of the most abundant peptides found in the mammalian central nervous system (CNS) and plays several important roles in regulating brain function. Physiological roles of NPY in the brain are mediated by at least six receptor subtypes (Y1 to Y6). In the present study, a rat Y1 receptor cRNA probe was used for in in situ hybridization experiments in order to determine the developmental profile of this receptor mRNA and to compare it with its translated protein using receptor autoradiography with the radiolabelled ligand [125I][Leu31,Pro34]PYY. The NPY Y1 receptor mRNA is expressed as early as by the 12th day of gestation while specific [125I][Leu31,Pro34]PYY binding is observed by day 14 of gestation. Thereafter, both signals steadily increased, with Y1 receptor mRNA increasing faster than its translated protein during fetal life. The in situ hybridization signals reached a plateau around birth and remained high during the first 2 post-natal weeks to display the adult distribution by the end of the 3rd post-natal week. Similarly, specific [125I][Leu31,Pro34]PYY binding constantly increased during brain maturation and reached a plateau by the end of the 3rd post-natal week. In some brain areas, such as the cerebral cortex, specific binding declined slightly before attaining its adulthood pattern. Throughout ontogenesis, the profile of both the Y1 receptor mRNA and protein was well-matched except in hypothalamic areas where relatively higher mRNA signals were observed. Taken together, these results along with previous reports describing NPY-like immunoreactivity in the early developmental rat brain, suggest that the NPY Y1 receptor may play an important role in early brain development and maturation on the basis of its very early pattern of embryonic expression.

A role for the SHP-2 tyrosine phosphatase in nerve growth-induced PC12 cell differentiation

SHP-1 and SHP-2 are intracellular protein tyrosine phosphatases containing two adjacent src homology 2 domains that target these phosphatases to cell surface receptor signaling complexes and play a role in receptor signal transduction. In this report the PC12 cell system was used to investigate the potential roles of SHP-1 and SHP-2 in the induction of neuronal differentiation by nerve growth factor (NGF). By using neurite outgrowth as a marker for differentiation, the effects of transfected constructs of SHP-1 and SHP-2 were assessed. Overexpression of a catalytically inactive SHP-2, but not a catalytically inactive SHP-1, blocked NGF-stimulated neurite outgrowth. The mitogen-activated protein kinase (MAPK) signaling cascade is important for the morphological differentiation in PC12 cells, and both SHP-1 and SHP-2 have been implicated to act upstream of MAPK in other receptor signaling systems. A positive role for SHP-2 but not SHP-1 in the activation of MAPK by NGF was demonstrated by introduction of the SHP-2 phosphatase mutants along with hemagglutinin-tagged MAPK. Coexpression studies with the SHP-2 mutant along with mutant forms of MAPK kinase suggested that SHP-2 functions upstream of MAPK kinase and MAPK in NGF-induced neurite outgrowth.

Protein-tyrosine phosphatase SHP2 is positively linked to proteinase-activated receptor 2-mediated mitogenic pathway

Proteinase-activated receptor-2 (PAR2), a new member of family of the G protein-coupled receptors, is activated by proteolytic cleavage of its extracellular amino terminus, a mechanism similar to that used by the thrombin receptor. It has been suggested that PAR2 has a potential role in the late phases of the acute inflammatory response and in tissue repair and/or skin-related disorders. Here we demonstrate that the agonist peptide (SLIGRL) stimulated c-fos-mediated mitogenic activation and tyrosine phosphorylation of cellular proteins. One of the tyrosine-phosphorylated proteins was identified as an Src homology-2 domain-containing protein-tyrosine phosphatase, SHP2. The stimulatory effect of the agonist peptide on early gene transcription was markedly blocked by pertussis toxin treatment whereas the induced tyrosine phosphorylation of SHP2 was completely abolished by the drug. More importantly, while expression of wild-type SHP2 enhanced the agonist-stimulatory mitogenic activity, overexpression of a catalytically inactive mutant of SHP2 strongly suppressed the stimulatory effect of the agonist peptide on both early gene transcription and DNA synthesis. These results suggest that SHP2 acts as a positive regulator linked to the PAR2-mediated mitogenic pathway coupled to a pertussis toxin-sensitive heterotrimeric G protein. Demonstration of SHP2 as a positive mediator in a G protein-coupled, receptor-mediated signaling adds to our understanding of the function of both SHP2 and PAR2 in the signaling pathway.

Octapeptide somatostatin analog SMS 201-995 induces translocation of intracellular PTP1C to membranes in MCF-7 human breast adenocarcinoma cells

Somatostatin (SST) analogs exert direct antiproliferative actions in pancreatic, pituitary, and mammary tumor cells in vitro. SST receptor (SSTR)-mediated induction of membrane-associated protein tyrosine phosphatase (PTP) activity has been implicated in its anti-proliferative signaling by virtue of its ability to dephosphorylate and inactivate growth factor receptor kinases. Recently, a PTP-containing Src homology 2 domain, identified as PTP1C/SHPTP1/SHP/HCP, was found to be associated with SSTR in rat pancreatic acinar cell membranes. In the present study we investigated the antiproliferative action of the octapeptide SST analog SMS 201-995 (OCT) and its effect on PTP activity in MCF-7 human breast adenocarcinoma cells. We report here that OCT does not directly stimulate membrane-associated PTP activity, but induces translocation of intracellular PTP to the membrane in MCF-7 cells preincubated with the peptide in a time- and concentration-dependent manner. We demonstrate that this is due at least in part to OCT-induced recruitment of cytosolic PTP1C. OCT-induced recruitment of PTP1C to the cell surface as well as its ability to inhibit the growth of MCF-7 cells was G protein dependent and inhibited by orthovanadate. These findings suggest that translocation of cytosolic PTP1C by SST analogs to the cell surface is an early event in its antiproliferative signaling in tumor cells.

Positive effect of overexpressed protein-tyrosine phosphatase PTP1C on mitogen-activated signaling in 293 cells

PTP1C, an SH2 domain-containing protein-tyrosine phosphatase, is predominantly expressed in hematopoietic cells, in which it negatively regulates cellular signaling. However, this enzyme is also expressed in many non-hematopoietic cells. We demonstrate here that in non-hematopoietic 293 cells, overexpression of a catalytically inactive mutant of PTP1C strongly suppressed the stimulatory effects of the epidermal growth factor or serum on cell proliferation, early gene transcription, and DNA synthesis. Similarly, the phosphorylation of the mitogen-activated protein kinase and mitogen-activated protein kinase kinase activity was markedly inhibited by overexpression of mutant PTP1C. The inhibitory effect of mutant PTP1C was overcome by cotransfection with wild-type PTP1C, but not with the structurally related PTP2C. Furthermore, expression of the mutant phosphatase resulted in hyperphosphorylation on tyrosine of a 95-kDa protein that was co-immunoprecipitated with the mutant, but not with the wild-type protein. These results suggest that, unlike in hematopoietic cells, PTP1C in 293 cells plays a positive role in epidermal growth factor- or serum-activated mitogenesis. Thus, PTP1C participates in multiple signaling pathways, where the enzyme, depending on its target molecules, may function as either a positive or negative mediator.

Expression of the neuropeptide Y Y1 receptor mRNA in the human brain: an in situ hybridization study

Using cRNA in situ hybridization, the regional distribution of mRNA encoding the human Y1 receptor was investigated in the normal human brain and compared with the autoradiographic distribution of putative Y1/[125I][Leu31,Pro34]PYY binding sites. Surprisingly, relatively high levels of Y1 receptor mRNA, distributed in a ty laminar fashion, were detected in the frontal and temporal cortices; laminae I, IV and VI were particularly enriched. The claustrum and nucleus of the medial geniculate body also revealed high levels of Y1 receptor mRNA signals. Moderate levels of specific hybridization were detected in the caudate nucleus, putamen, nucleus accumbens, amygdaloid nuclei, and arcuate and paraventricular nuclei of the hypothalamus. In all these regions, only very low levels of specific [125I][Leu31,Pro34]PYY binding were detected with the exception of the dentate gyrus of the hippocampal formation which expressed rather high levels of both the Y1 receptor mRNA and its translated protein. Accordingly, the human brain can express the Y1 receptor mRNA but this may not necessarily translate into a functional receptor as revealed by low specific binding levels observed in most regions.

Localization and down-regulating role of the protein tyrosine phosphatase PTP2C in membrane ruffles of PDGF-stimulated cells

PTP2C (also known as Syp/SH-PTP2/PTPlD) is a soluble protein tyrosine phosphatase present in most cell types. It interacts directly with activated PDGF receptor via its SH2 domains, which results in its phosphorylation on tyrosine residue(s). The phosphorylated PTP2C in turn binds to the SH2 domain of GRB2, serving as an adaptor in the transduction of mitogenic signals from the growth factor receptor to the Ras and MAP kinase signaling pathways. We investigated the interaction of PTP2C with the PDGF receptor by examining the localization of both proteins after PDGF stimulation of 293 cells which stably express the human PDGF receptor. In resting cells, transiently expressed PTP2C was distributed throughout the cytoplasm. Upon stimulation with PDGF, PTP2C was translocated from the cytoplasm to membrane ruffles. Immunofluorescence examination revealed that PTP2C colocalized with actin, the PDGF receptors, and hyper-tyrosine- phosphorylated protein(s). Neither deletion of the SH2 domains nor point mutations at either the catalytic site or the major phosphorylation site affected membrane ruffling or the localization of PTP2C to the ruffles of PDGF-stimulated cells. However, the expression of a catalytically inactive mutant PTP2C substantially prolonged ruffling activity following PDGF stimulation. These results suggest that PTP2C is involved in the down-regulation of the membrane ruffling pathway, and in contrast to its positive function in the MAP kinase pathway, the phosphatase activity negatively regulates ruffling activity.

CD22 associates with protein tyrosine phosphatase 1C, Syk, and phospholipase C-gamma(1) upon B cell activation

Cross-linking B cell antigen receptor (BCR) elicits early signal transduction events, including activation of protein tyrosine kinases, phosphorylation of receptor components, activation of phospholipase C-gamma (PLC-gamma), and increases in intracellular free Ca2+. In this article, we report that cross-linking the BCR led to a rapid translocation of cytosolic protein tyrosine phosphatase (PTP) 1C to the particulate fraction, where it became associated with a 140-150-kD tyrosyl-phosphorylated protein. Western blotting analysis identified this 140-150-kD protein to be CD22. The association of PTP-1C with CD22 was mediated by the NH2-terminal Src homology 2 (SH2) domain of PTP-1C. Complexes of either CD22/PTP-1C/Syk/PLC-gamma(1) could be isolated from B cells stimulated by BCR engagement or a mixture of hydrogen peroxidase and sodium orthovanadate, respectively. The binding of PLC-gamma(1) and Syk to tyrosyl-phosphorylated CD22 was mediated by the NH2-terminal SH2 domain of PLC-gamma(1) and the COOH-terminal SH2 domain of Syk, respectively. These observations suggest that tyrosyl-phosphorylated CD22 may downmodulate the activity of this complex by dephosphorylation of CD22, Syk, and/or PLC-gamma(1). Transient expression of CD22 and a null mutant of PTP-1C (PTP-1CM) in COS cells resulted in an increase in tyrosyl phosphorylation of CD22 and its interaction with PTP-1CM. By contrast, CD22 was not tyrosyl phosphorylated or associated with PTP-1CM in the presence of wild-type PTP-1C. These results suggest that tyrosyl-phosphorylated CD22 may be a substrate for PTP-1C regulates tyrosyl phosphorylation of CD22.

Expression of the neuropeptide Y Y1 receptor in human embryonic kidney 293 cells: ligand binding characteristics, in situ hybridization and receptor autoradiography

The human neuropeptide Y Y1 receptor cDNA was transfected into human embryonic kidney 293 (HEK 293) cells and used to determine the selectivity of newly developed Y1 and Y2 radioligands in a model which expresses a single NPY receptor subtype. The Y1 receptor probe, [125I][Leu31,Pro34]PYY, binds with high afinity (KD of 0.4-0.6 nM) to Y1-transfected HEK 293 cells whereas the Y2 radioligand, [125I]PPY3-36 failed to demonstrate any significant labelling. Only non-selective (PYY) or selective Y1 receptor agonists behaved as potent competitors for [125I][Leu31,Pro34]PYY binding in transfected cells. Additionally, the efficacy of the transfection method used was evaluated at both the transcriptional and translational levels. In situ hybridization revealed the heterogeneous distribution of the NPY Y1 receptor mRNA expressed in transfected HEK 293 cells. Similarly, the levels of NPY Y1 binding sites per transfected cell varied as shown using [125I][Leu31,Pro34]PYY receptor autoradiography. Taken together, these results demonstrate that HEK 293 cells transfected with the NPY Y1 receptor cDNA expressed both the related receptor mRNA and protein albeit at different levels depending upon each transfected cell. Additionally, these data further establish the selectivity of the newly developed Y1 and Y2 radioligands.

Regulation of protein tyrosine phosphatase 1C: opposing effects of the two src homology 2 domains

The regulatory roles of the two src homology 2 (SH2) domains of protein tyrosine phosphatase 1C were investigated by comparing recombinant full-length PTP1C with mutants in which either the N-terminal SH2 (N-SH2) domain (PTP1C delta NSH2), the C-terminal SH2 (C-SH2) domain (PTP1C delta CSH2) or both SH2 domains were deleted (PTP1C delta NSH2 delta CSH2). This revealed that the SH2 domains have opposing and independent effects on activity: strong inhibition by N-SH2 (42-fold) and weak activation by C-SH2 (2.1-fold). C-SH2 caused activation across a wide pH range while N-SH2 inhibited most at neutral and high pH through a shift of the basic limb of the pH profile of kcat/Km, apparently via perturbation of an active-site pKa value. A phosphotyrosyl peptide derived from the erythropoietin receptor caused an approximately 30-fold activation of PTP1C and PTP1C delta CSH2 but had no effect on PTP1C delta NSH2 or PTP1C delta NSH2 delta CSH2, indicating that binding of this peptide to N-SH2 abolished its inhibition. Since C-SH2 separates N-SH2 from the catalytic domain in full-length PTP1C and activation is observed for PTP1C delta CSH2, it appears that the inhibitory effect of N-SH2 is independent of the position in the sequence and that intermolecular interactions may also be possible.