L1 Cell Adhesion Molecule (L1CAM) Expression and Molecular Alterations Distinguish Low-Grade Oncocytic Tumor From Eosinophilic Chromophobe Renal Cell Carcinoma

Renal low-grade oncocytic tumor (LOT) is a recently recognized renal cell neoplasm designated within the "other oncocytic tumors" category in the 2022 World Health Organization classification system. Although the clinicopathologic, immunohistochemical, and molecular features reported for LOT have been largely consistent, the data are relatively limited. The morphologic overlap between LOT and other low-grade oncocytic neoplasms, particularly eosinophilic chromophobe renal cell carcinoma (E-chRCC), remains a controversial area in renal tumor classification. To address this uncertainty, we characterized and compared large cohorts of LOT (n = 67) and E-chRCC (n = 69) and revealed notable differences between the 2 entities. Clinically, LOT predominantly affected women, whereas E-chRCC showed a male predilection. Histologically, although almost all LOTs were dominated by a small-nested pattern, E-chRCC mainly showed solid and tubular architectures. Molecular analysis revealed that 87% of LOT cases harbored mutations in the tuberous sclerosis complex (TSC)-mTOR complex 1 (mTORC1) pathway, most frequently in MTOR and RHEB genes; a subset of LOT cases had chromosomal 7 and 19q gains. In contrast, E-chRCC lacked mTORC1 mutations, and 60% of cases displayed chromosomal losses characteristic of chRCC. We also explored the cell of origin for LOT and identified L1 cell adhesion molecule (L1CAM), a collecting duct and connecting tubule principal cell marker, as a highly sensitive and specific ancillary test for differentiating LOT from E-chRCC. This distinctive L1CAM immunohistochemical labeling suggests the principal cells as the cell of origin for LOT, unlike the intercalated cell origin of E-chRCC and oncocytoma. The ultrastructural analysis of LOT showed normal-appearing mitochondria and intracytoplasmic lumina with microvilli, different from what has been described for chRCC. Our study further supports LOT as a unique entity with a benign clinical course. Based on the likely cell of origin and its clinicopathologic characteristics, we propose that changing the nomenclature of LOT to "Oncocytic Principal Cell Adenoma of the Kidney" may be a better way to define and describe this entity.

L1CAM Is Not a Predictive Factor in Early-stage Squamous-cell Cervical Cancer

AIM

Our study aimed to assess expression of L1 cell adhesion molecule (L1CAM) in early-stage cervical squamous-cell cancer as a prognostic factor.

PATIENTS AND METHODS

This retrospective, single-institution study included 154 patients who underwent radical hysterectomy for early-stage squamous cell cervical cancer between 2007 and 2017. Tumor samples from 154 patients were available for L1CAM analysis by immunohistochemistry. Among all patients, radical abdominal hysterectomy was performed in 144 cases.

RESULTS

L1CAM expression was positive in 24 tumors (15.6%) of the whole group. In relation to the grade of differentiation and the presence of lymphovascular invasion, L1CAM expression did not show an association (p=0.154 and p=0.306, respectively). The disease-free interval and overall survival also did not significantly differ between L1CAM-positive and L1CAM-negative cases (p=0.427 and p=0.240, respectively). For histopathological characteristics, L1CAM-positive cases had a significantly higher median tumor size (p=0.015). Even in the selected group of 115 cases without nodal infiltration, L1CAM status had no effect on the relapse rate during follow-up.

CONCLUSION

Our study did not confirm the results of previous studies showing L1CAM expression to be a negative prognostic factor in cervical cancer. In our study, increased L1CAM expression in early-stage squamous-cell cervical cancer was not associated with adverse prognosis regarding disease recurrence, disease-free survival, nor overall survival. L1CAM expression was correlated only with the size of the tumor.

Addition of IMP3 to L1CAM for discrimination between low- and high-grade endometrial carcinomas: a European Network for Individualised Treatment of Endometrial Cancer collaboration study

Discrimination between low- and high-grade endometrial carcinomas (ECs) is clinically relevant but can be challenging for pathologists, with moderate interobserver agreement. Insulin-like growth factor-II mRNA-binding protein 3 (IMP3) is an oncofoetal protein that is associated with nonendometrioid endometrial carcinomas but has been limited studied in endometrioid carcinomas. The aim of this study is to investigate the diagnostic and prognostic value of IMP3 in the discrimination between low- and high-grade ECs and its added value to L1CAM. IMP3 and L1CAM expression was assessed in tumors from 378 patients treated for EC at 1 of 9 participating European Network for Individualised Treatment of Endometrial Cancer centers. IMP3 was expressed in 24.6% of the tumors. In general, IMP3 was more homogeneously expressed than L1CAM. IMP3 expression was significantly associated with advanced stage, nonendometrioid histology, grade 3 tumors, deep myometrial invasion, lymphovascular space invasion, distant recurrences, overall mortality, and disease-related mortality. Simultaneous absence of IMP3 and L1CAM expression showed the highest accuracy for identifying low-grade carcinomas (area under the curve 0.766), whereas simultaneous expression of IMP3 and L1CAM was strongly associated with high-grade carcinomas (odds ratio 19.7; 95% confidence interval 9.2-42.2). Even within endometrioid carcinomas, this combination remained superior to IMP3 and L1CAM alone (odds ratio 8.6; 95% confidence interval 3.4-21.9). In conclusion, IMP3 has good diagnostic value and together with L1CAM represents the optimal combination of diagnostic markers for discrimination between low- and high-grade ECs compared to IMP3 and L1CAM alone. Because of the homogenous expression of IMP3, this marker might be valuable in preoperative biopsies when compared to the more patchy L1CAM expression.

Sialic Acid and Sialylated Oligosaccharide Supplementation during Lactation Improves Learning and Memory in Rats

Sialic acids (Sia) are postulated to improve cognitive abilities. This study evaluated Sia effects on rat behavior when administered in a free form as N-acetylneuraminic acid (Neu5Ac) or conjugated as 6'-sialyllactose (6'-SL). Rat milk contains Sia, which peaks at Postnatal Day 9 and drops to a minimum by Day 15. To bypass this Sia peak, a cohort of foster mothers was used to raise the experimental pups. A group of pups received a daily oral supplementation of Neu5Ac to mimic the amount naturally present in rat milk, and another group received the same molar amount of Sia as 6'-SL. The control group received water. After weaning, rats were submitted to behavioral evaluation. One year later, behavior was re-evaluated, and in vivo long-term potentiation (LTP) was performed. Brain samples were collected and analyzed at both ages. Adult rats who received Sia performed significantly better in the behavioral assessment and showed an enhanced LTP compared to controls. Within Sia groups, 6'-SL rats showed better scores in some cognitive outcomes compared to Neu5Ac rats. At weaning, an effect on polysialylated-neural cell adhesion molecule (PSA-NCAM) levels in the frontal cortex was only observed in 6'-SL fed rats. Providing Sia during lactation, especially as 6'-SL, improves memory and LTP in adult rats.

In vivo functional heterogeneity among β-cells

The concept of functional heterogeneity among β-cells proposes that each cell differs in its sensitivity to glucose and is recruited in a glucose-dependent manner into both biosynthetic and secretory active states in order to adapt insulin secretion to the metabolic environment. Therefore, characterization of β-cell populations with different metabolic sensitivities would lead to the development of new therapeutic strategies. Based on heterogeneous surface PSA-NCAM expression on β-cells, we have recently characterized two groups of cells, namely β(high) and β(low)-cells, in rat. Differences in insulin secretory capacity and in gene expression profiles suggest that β(low)-cells are immature and/or non-functional cells in contrast to highly glucose responsive fully functional β(high)-cells. Moreover, the relative distribution of β(high) and β(low)-cells correlated with physiological and pathological states regarding the functional β-cell mass. Here we summarize our main results on β(high) and β(low)-cell populations and discuss some of the open remaining questions.

Waist circumference, atherogenic lipoproteins, and vascular smooth muscle biomarkers in children

OBJECTIVE

Large waist circumference (WC) is associated with cardiovascular disease and type 2 diabetes. The present study determined differences in lipoprotein particle size and subclass concentration and markers of vascular smooth muscle function in children using WC percentile cutoffs.

RESEARCH DESIGN AND METHODS

Participants were 182 children (87 black, 92 female) aged 8-<18 yr. Each participant had a measurement of WC and a fasting blood draw for the measurement of lipoprotein particle concentration and size and circulating biomarkers of endothelial function. Participants were divided into age-, sex-, and ethnicity-specific WC percentiles of below 75th, 75th to 90th, and at least 90th percentiles, and differences in lipoproteins and vascular smooth muscle markers were compared among groups.

RESULTS

Children in the 90th percentile or higher for WC had significantly smaller low-density lipoprotein and high-density lipoprotein size than children with WC below this percentile. For lipoprotein concentration, small low-density lipoprotein and large very low density lipoprotein and chylomicrons were lower, and large high density lipoprotein concentrations were higher in children whose WC was below the 75th percentile compared with those with WC in the 90th percentile or higher. Concentrations of the vascular smooth muscle biomarkers, intercellular adhesion molecule-1, and E-selectin were significantly higher in children with WC in the 90th percentile or higher than in children below the 75th percentile.

CONCLUSION

Youths with WC in the 90th percentile or higher have an atherogenic lipoprotein profile with increased concentrations of biomarkers of vascular smooth muscle dysfunction. Given that atherosclerosis begins in childhood, such evidence suggests that these children should be targeted for interventions to reduce adiposity at an early age.

Merkel Cells, Normal and Neoplastic: An Update

Merkel cells (MC) occur in the basal epidermal layer, hair follicles, and oral mucosa, as complexes with sensory axons. The axons transduce slowly adapting type I mechanoreception, and MC modulate their sensitivity. MC also determine and maintain the 3-dimensional epidermal structure. They have neuroendocrine granules, rigid spinous processes, and desmosomal junctions with each other and with keratinocytes. Rare MC are dermaWl. Current evidence supports a basal cell origin. Merkel cell carcinomas (MCC) occur mostly in sun-exposed skin in old age. Trabecular, intermediate, or small cell in pattern, MCC have neuroendocrine granules, intercellular junctions, rigid spinous processes, and a paranuclear collection of intermediate filaments staining for cytokeratin 20. Most MCC behave indolently, but those with the small cell pattern, and some with the intermediate pattern, are aggressive and rapidly fatal.

A simple two-step protocol for the purification of human pancreatic beta cells

AIMS/HYPOTHESIS

Isolated pure human beta cells would be helpful for a number of research purposes. However, lack of beta cell-specific surface antigens has been a major problem. We aimed to develop a simple method for human beta cell isolation based on the initial elimination of ductal cells by their expression of carbohydrate antigen 19-9 (CA19-9), followed by positive selection of beta cells by their expression of polysialic acid-neural cell adhesion molecule (PSA-NCAM).

METHODS

Cell type-specific expression of CA19-9, NCAM and PSA-NCAM was studied in sections of adult human pancreas and in cultured primary endocrine and exocrine cells. Dispersed human islet cells were purified in two steps, after 4 days of suspension culture, by binding to magnetic microbeads coupled to antibodies against CA19-9 and PSA-NCAM.

RESULTS

NCAM expression was detected in ducts and islets in the human pancreas. In contrast, PSA-NCAM immunoreactivity was detected only in islets. PSA-NCAM staining in dispersed cells revealed that the marker is expressed in all endocrine cell types, but not in duct cells. Purification of dispersed islet cells using PSA-NCAM microbeads alone did not completely eliminate contaminating duct cells. However, elimination of the duct cells by CA19-9 microbeads followed by positive sorting of the PSA-NCAM-positive cells in five consecutive islet preparations resulted in 90 to 98% pure endocrine cells, of which 89 to 97% were beta cells.

CONCLUSIONS/INTERPRETATION

We describe a simple and reproducible method for purification of viable human pancreatic beta cells devoid of exocrine acini and ducts.

Adeno-associated virus-mediated L1 expression promotes functional recovery after spinal cord injury

Paucity of permissive molecules and abundance of inhibitory molecules in the injured spinal cord of adult mammals prevent axons from successful regeneration and, thus, contribute to the failure of functional recovery. Using an adeno-associated viral (AAV) vector, we expressed the regeneration-promoting cell adhesion molecule L1 in both neurons and glia in the lesioned spinal cord of adult mice. Exogenous L1, detectable already 1 week after thoracic spinal cord compression and immediate vector injection, was expressed at high levels up to 5 weeks, the longest time-period studied. Dissemination of L1-transduced cells throughout the spinal cord was wide, spanning over more than 10 mm rostral and 10 mm caudal to the lesion scar. L1 was not detectable in the fibronectin-positive lesion core. L1 overexpression led to improved stepping abilities and muscle coordination during ground locomotion over a 5-week observation period. Superior functional improvement was associated with enhanced reinnervation of the lumbar spinal cord by 5-HT axons. Corticospinal tract axons did not regrow beyond the lesion scar but extended distally into closer proximity to the injury site in AAV-L1-treated compared with control mice. The expression of the neurite outgrowth-inhibitory chondroitin sulphate proteoglycan NG2 was decreased in AAV-L1-treated spinal cords, along with reduction of the reactive astroglial marker GFAP. In vitro experiments confirmed that L1 inhibits astrocyte proliferation, migration, process extension and GFAP expression. Analyses of intracellular signalling indicated that exogenous L1 activates diverse cascades in neurons and glia. Thus, AAV-mediated L1 overexpression appears to be a potent means to favourably modify the local environment in the injured spinal cord and promote regeneration. Our study demonstrates a clinically feasible approach of promising potential.

Human neuroblasts migrate to the olfactory bulb via a lateral ventricular extension

The rostral migratory stream (RMS) is the main pathway by which newly born subventricular zone cells reach the olfactory bulb (OB) in rodents. However, the RMS in the adult human brain has been elusive. We demonstrate the presence of a human RMS, which is unexpectedly organized around a lateral ventricular extension reaching the OB, and illustrate the neuroblasts in it. The RMS ensheathing the lateral olfactory ventricular extension, as seen by magnetic resonance imaging, cell-specific markers, and electron microscopy, contains progenitor cells with migratory characteristics and cells that incorporate 5-bromo-2'-deoxyuridine and become mature neurons in the OB.

The adhesion molecule L1 (CD171) promotes melanoma progression

The adhesion molecule L1 is expressed in primary melanomas and cutaneous metastases in contrast to melanocytic nevi and melanocytes, and is significantly associated with metastatic spread. Recent studies have demonstrated that in carcinomas L1 expression is associated with sustained activation of the extracellular signal-regulated kinase (ERK) pathway and upregulation of ERK-dependent, motility- and invasion-associated gene products including alphavbeta3 integrin. The objective of this study was to further investigate the role of the adhesion molecule L1 in melanoma progression, and to evaluate whether targeting the L1 adhesion molecule would have therapeutic effects against invasive melanoma growth. Using human melanoma cells from different stages of progression in monolayer and organotypic human skin culture mimicking the pathophysiological environment of cutaneous melanoma, we found that (1) L1 expression mostly correlates with melanoma progression and alphavbeta3 integrin expression, (2) overexpression of L1 in early radial growth phase melanoma cells promotes conversion from radial to vertical growth phase melanoma without upregulation of alphavbeta3 integrin expression, and (3) suppression of L1 function significantly reduces migration and invasion of melanoma cells, but does not completely block invasive melanoma growth. Altogether, L1 plays a critical role in melanoma invasion and progression and offers therapeutic potential in combination with conventional anticancer agents.

[The use of immunohistochemistry in the differential diagnosis of thyroid gland tumors with follicular growth pattern]

The aim of the study was to evaluate the expression of galectin-3 (gal3), cytokeratin 19 (CK19), neural cell adhesion molecule (NCAM), and E-cadherin (Ecad) in thyroid gland tumors with follicular growth pattern with particular focus on their use in differential diagnosis. A series of 139 cases - 87 follicular adenomas (FAs), 26 follicular carcinomas (FCs), and 26 cases of the follicular variant of papillary carcinoma (FVPC) was studied. Expression of gal3 was found in 29/87 (33%) of FAs, in 13/26 (50%) of FCs, and in 24/26 (92%) of FVPCs. Expression of CK19 was found in 11/87 (13%) of FAs, in 4/26 (15%) of FCs, and in 17/26 (65%) of FVPCs. Expression of NCAM was found in 60/87 (69%) of FAs, in 20/26 (77%) of FCs, and in 7/26 (27%) FVPCs. Expression of Ecad was found in 81/87 (93%) of FAs, in 22/26 (85%) of FCs, and in 17/26 (65%) of FVPCs. The sensitivity and specificity of gal3 for malignancy were 0.70 and 0.85, of CK19 0.48 and 0.98, of NCAM 0.28 and 0.47, and of Ecad 0.48 and 0.20, respectively. A significant difference (p < 0.05) in expression of all studied markers between FVPC versus FA and FC was found, in contrast to FA and FC. Therefore, the use of gal3 and CK19 in differential diagnosis of FVPC versus FA and FC can be recommended.

L1 is a potential marker for poorly-differentiated pancreatic neuroendocrine carcinoma

AIM: To determine the expression of L1 in pancreatic neuroendocrine tumor and to correlate it with WHO classification of this tumor.

METHODS: We retrospectively analyzed L1 expression in 63 cases of pancreatic neuroendocrine tumor by immunohistochemistry on paraffin sections of primary tumors or metastases. Staining was performed by peroxidase technique with monoclonal antibody UJ127.11 against human L1. All tumors were classified according to WHO classification as well-differentiated neuroendocrine tumors and carcinomas or poorly-differentiated neuroendocrine carcinomas.

RESULTS: L1 was detected in 5 (7.9%) of 63 pancreatic neuroendocrine tumors. Four (44.4%) of 9 poorly-differentiated carcinomas expressed L1. In contrast, only 1 (1.9%) of 54 well-differentiated tumors or carcinomas was positive for L1. No expression was found in Langerhans islet cells of normal pancreatic tissue. Cross table analysis showed a significant association between L1 expression and classification of neuroendocrine tumors of the pancreas (P<0.01).

CONCLUSION: L1 is specifically expressed in poorly-differentiated pancreatic neuroendocrine carcinomas that are known to have the worst prognosis. L1 might be a marker for risk prediction of patients diagnosed with pancreatic neuroendocrine carcinomas.

L1 CAM expression in the superficial dorsal horn is derived from the dorsal root ganglion

The cell adhesion molecule L1 is highly expressed on embryonic axons and may play a role in axonal outgrowth and fasciculation. Generally only low levels of L1 are found in adult spinal cord except for intense labeling in Lissauer's tract, in laminae I-II, and on dorsolateral funicular axons. In this study we determine the source of L1 immunoreactivity in the dorsal spinal cord, the presence of L1 expression on sprouting axons, and the effect of exercise on L1 expression. We determined the source of L1 immunoreactivity in the superficial dorsal horn by performing acute unilateral rhizotomies (T12-L4) in adult rats. This resulted in a marked decrease in L1 expression in Lissauer's tract and laminae I-II on the deafferented side. The peptidergic and nonpeptidergic small-diameter primary afferent markers, calcitonin gene-related peptide (CGRP) and the lectin IB4 respectively, closely correlated with L1 expression and also decreased dramatically after rhizotomy. Considering its developmental role, we asked whether L1 was expressed on sprouting axons following chronic rhizotomy. L1 and CGRP, but not IB4, were detected on sprouting axons. Lastly, we investigated the effect of exercise on L1 expression by giving animals with chronic rhizotomies free access to an exercise wheel. After extensive exercise, L1, CGRP, and IB4 expression levels were unchanged compared with those of sedentary chronic animals. Combined, these data demonstrate that the dorsal root ganglia is a major source of L1-positive axons in the superficial dorsal horn, that both L1 and CGRP identify sprouting axons following rhizotomy, and that exercise does not upregulate L1 expression.

Nasal and frontal sinus mucosa of the adult dog contain numerous olfactory sensory neurons and ensheathing glia

Olfactory glial cells have been the focus of much recent research interest because of their possible future use as cellular transplants in repair of spinal cord injury. Although olfactory glial cells can be collected from the olfactory bulb for in vitro culture, alternative sites would be preferable for safer surgical access. This study was designed to investigate the distribution of olfactory sensory neurons and olfactory glial cells within the canine peripheral olfactory system. Using immunohistochemistry and electron microscopy on perfused tissue we demonstrate that olfactory sensory neurons are found in both the caudal nasal and the frontal sinus epithelia. Olfactory ensheathing glia were found in the mucosa at both these sites implying that surgical access for harvesting cells for transplantation would be straightforward.

Clinicopathological study of cellular proliferation and invasion in gliomatosis cerebri: important role of neural cell adhesion molecule L1 in tumour invasion

BACKGROUND/AIMS

In patients with gliomatosis cerebri (GC), glial fibrillary acidic protein (GFAP) positive cells invade the entire brain, particularly the white matter. Because the nosological definition and histogenesis of GC remain controversial, the morphology and immunohistochemical staining patterns of neoplastic GC cells were compared with those of other gliomas.

METHODS

An immunohistochemical analysis of neoplastic cells from four patients with GC and 20 with astrocytic tumours using antibodies against Ki-67, GFAP, and L1, the last of which is a neural cell adhesion molecule putatively related to glioma invasion.

RESULTS

GC tumour cells can be divided into two types, those mainly composed of strongly GFAP and L1 positive gemistocytic cells, the other composed of small, GFAP and L1 negative spindle shaped cells. The two types did not differ with respect to Ki-67 positivity. Cells from patients with other gliomas were positive for GFAP but concurrent L1 expression was negative or weakly positive.

CONCLUSION

The strong expression of L1 in patients with GC and its poor expression in the 20 patients with other types of glioma, including those with GFAP positive gemistocytic astrocytomas, suggest that L1 expression may play a role in the histogenesis of GC.

Identification of L1CAM, Jagged2 and Neuromedin U as ovarian cancer-associated antigens

In order to identify tumor-associated genes of ovarian carcinoma, we have investigated the transcriptional profile of 11 ovarian tumor cell lines and 2 immortalized ovarian surface epithelial cell lines (IOSE) derived from normal ovarian epithelium with Affymetrix GeneChip technology. We have analyzed the expression profile of 12652 genes. A total of 136 genes were up-regulated and 165 were down-regulated in at least 7 out of 11 ovarian tumor cell lines in comparison to the transcriptional profile of the IOSE cell lines with a change factor of +/-2 as the threshold level. We have focused on up-regulated genes encoding for transmembrane receptors and secreted proteins as possible markers for diagnosis and targets for therapy of ovarian carcinoma. We have identified the transmembrane Notch ligand Jagged2, cell adhesion molecule L1CAM and the secreted polypeptide Neuromedin U as possible candidates. Immunohistochemical analysis revealed expression of L1CAM predominantly in ovarian carcinomas, in borderline tumors to a lesser extent, and very rarely in ovarian non-epithelial types of cancer. Further analysis of L1CAM revealed that a splice variant lacking exons 2 and 27 is predominantly expressed in ovarian carcinoma cell lines DW and GG. Functional investigation of stable Delta(2,27)L1CAM transfectants of the ovarian tumor cell line OV-MZ-2 revealed significantly stronger adhesion to laminin in comparison to mock transfectants.

The L1 cell adhesion molecule is induced in renal cancer cells and correlates with metastasis in clear cell carcinomas

PURPOSE

The L1 cell adhesion molecule is overexpressed in many human carcinomas. The objectives of the study were to provide a comprehensive description of L1 distribution in human kidney and to establish the prognostic relevance of L1 expression in renal cell carcinomas (RCC).

EXPERIMENTAL DESIGN

Using two antibodies to the extracellular part and the cytoplasmic domain, respectively, we first compared L1 expression in normal kidney and renal tumors of diverse histopathologic origin, then we studied L1 expression together with tumor stage, grade, molecular prognostic biomarkers, and metastatic behavior.

RESULTS

In normal kidney, L1 immunoreactive with both antibodies was expressed in all epithelial cells originating from the ureteric bud except for intercalated cells. In renal tumors, L1 was mainly detected in those originating from cells that do not express L1 in the normal kidney [i.e., 33 of 72 clear cell RCC (ccRCC) and 25 of 88 papillary RCC (papRCC)]. Both in ccRCC and papRCC, L1 reacted only with the antibody to the extracellular domain, suggesting that the protein was truncated. In these carcinomas, L1 expression was strongly correlated with Ki-67 proliferation index (ccRCC, P = 0.0059; papRCC, P = 0.0039), but only in ccRCC, the presence of L1 was associated with the risk of metastasis (P = 0.0121). This risk was higher if cyclin D1 was concurrently absent in tumor cells (P < 0.0001). The L1(+)/cyclin D1(-) profile was an independent prognostic factor of metastasis occurrence in multivariate analysis (P = 0.0023).

CONCLUSION

We have found a combination of markers that can serve to identify a subgroup of high-risk patients with ccRCC that may require more aggressive therapies.

Hippocampal neurogenesis and PSA-NCAM expression following exposure to 56Fe particles mimics that seen during aging in rats

Exposure to particles of high energy and charge can disrupt the neuronal systems as well as the motor and cognitive behaviors mediated by these systems in a similar fashion to that seen during the aging process. In the hippocampus, adult neurogenesis is affected both by aging and irradiation with ionizing particles. Likewise, the maturation of newly formed cells in this region as measured by PSA-NCAM expression is also altered by the aging process. The present study was designed to investigate the effects of 2.5 Gy of 1 GeV/n (56)Fe particles on neurogenesis using the nuclear proliferation marker 5-bromodeoxyuridine (BrdU and PSA-NCAM expression in the dentate gyrus of rats exposed to whole-body irradiation or simply placed in the chamber without being irradiated. All subjects (n=10) were sacrificed 28 days after the last BrdU injection (50 mg/kg X 3 days) and their brains were processed for immunohistochemistry. Results illustrate a decrease in the number of BrdU-positive cells as well as different distribution of these cells in the dentate gyrus of irradiated animals. Additionally, irradiated subjects show decreased levels of PSA-NCAM expression. These changes are consistent with those found in aged subjects indicating that heavy-particle irradiation is an adequate model for the study of aging.

Negative regulation of hepatocellular carcinoma cell growth by signal regulatory protein alpha1

Signal regulatory protein (SIRP) alpha1 is a member of the SIRP family that undergoes tyrosine phosphorylation and binds SHP-2 tyrosine phosphatase in response to various mitogens. The expression levels of SIRPalpha1 were decreased in HCC tissues, compared with the matched normal tissues. Exogenous expression of wild type SIRPalpha1, but not of a mutant SIRPalpha1 lacking the tyrosine phosphorylation sites, in SIRPalpha1-negative Huh7 human HCC cells resulted in suppression of tumor cell growth both in vitro and in vivo. Treatment of Huh7 transfectants with EGF or HGF induced tyrosine phosphorylation of SIRPalpha1 and its association with SHP-2, which were accompanied by reduced ERK1 activation. Expression of SIRPalpha1 significantly suppressed activation of NF-kappaB and also sensitized Huh7 cells to TNFalpha or cisplatin-induced cell death. In addition, SIRPalpha1-transfected Huh7 cells displayed reduced cell migration and cell spreading in a fashion that was dependent on SIRPalpha1/SHP-2 complex formation. In conclusion, a negative regulatory effect of SIRPalpha1 on hepatocarcinogenesis is exerted, at least in part, through inhibition of ERK and NF-kappaB pathways.

Involvement of highly polysialylated neural cell adhesion molecule (PSA-NCAM)-positive granule cells in the amygdaloid-kindling-induced sprouting of a hippocampal mossy fiber trajectory

The mossy fiber system in the hippocampus of amygdaloid-kindled rats was examined by using highly polysialylated neural cell adhesion molecule (PSA-NCAM) as a marker for immunohistochemical detection of immature dentate granule cells and mossy fibers in combination with bromodeoxyuridine (BrdU) labeling of newly generated granule cells. Statistically significant increases in BrdU-labeled cells and PSA-NCAM-positive cells occurred in the dentate gyrus following kindling. The increase in PSA-NCAM-immunoreactive neurites was confined to the entire stratum lucidum of CA3. Immunoelectron-microscopic examination also revealed that PSA-NCAM-positive immature synaptic terminals of the sprouting mossy fibers increased in the stratum lucidum of CA3 in the kindled rats. The increase in the numbers of PSA-NCAM-positive granule cells correlated well with the increase in the immunopositive neurites and synaptic terminals on the mossy fiber trajectory. The increase in these PSA-NCAM-immunopositive structures is thought to reflect the enhancement of sprouting and synaptogenesis of mossy fibers by a subset of granule cells newly generated during amygdaloid-kindling and suggests that the reorganization of the mossy fiber system on the normal trajectory at least in part contributes to the acquisition and maintenance of an epileptogenic state.

Expression of L1 decreases during postnatal development of rat spinal cord

L1 is a cell adhesion molecule that is highly expressed on developing axons and is associated with neurite outgrowth, guidance, and fasciculation. In this study we systematically examined L1 expression at all spinal levels across eight postnatal ages to detect regional and developmental differences. We observed striking changes in the developmental pattern of L1 expression between birth (P0) and adult ages, with intense L1-immunopositive axons prevalent throughout the funiculi at P0 compared with predominantly L1-immunonegative funicular axons in adults. At all ages and spinal levels examined, some L1-positive dorsal root afferents entered the spinal cord, coursed in Lissauer's tract, and projected into the superficial dorsal horn and the dorsal columns, as well as across the dorsal commissure. Additional L1-positive axons were detected consistently around the perimeter of the spinal cord, in the dorsolateral funiculus, and adjacent to the central canal. While specific L1-labeled axons were detected at all ages, a pattern of segmental variation was observed within animals, with the highest levels of L1 expression detected in lumbar and sacral segments and the lowest in cervical spinal cord. The pattern of L1 immunoreactivity was compared to that of the growth-associated protein GAP-43 and the results indicated colabeling of most axons. These observations demonstrate that L1 is expressed on immature axons well into postnatal development, possibly until they have completed their differentiation. Furthermore, the L1-positive axons that continue to be detected in adults are likely to be either unmyelinated or sprouting axons.

Regionally specific expression of L1 and sialylated NCAM in the retinofugal pathway of mouse embryos

We have examined expression of L1 and the polysialic acid-associated form of the neural cell adhesion molecule (PSA-NCAM) in mouse embryos during the major period of axon growth in the retinofugal pathway to determine whether they are expressed in patterns that relate to the changes in axon organization in the pathway. Immunostaining for L1 and PSA-NCAM was found on all axons in the retina and the optic stalk. In the chiasm, while L1 immunoreactivity remained high on the axons, PSA-NCAM staining was obviously reduced. At the threshold of the optic tract, L1 immunoreactivity was maintained only in a subpopulation of axons, whereas PSA-NCAM staining was dramatically elevated in axons at the caudal part of the tract. Further investigations of the tract showed that both L1 and PSA-NCAM were preferentially expressed on the dorsal but not ventral optic axons, indicating a regionally specific change of both adhesion molecules on the axons at the chiasm-tract junction. Moreover, intense PSA-NCAM expression was also observed in the tract of postoptic commissure (TPOC), which lies immediately caudal to the optic tract. Immunohistochemical and retrograde tracing studies showed that these PSA-NCAM-positive axons arose from a population of cells rostral to the CD44-positive chiasmatic neurons. These findings indicate that, in addition to the chiasmatic neurons, these PSA-NCAM-positive diencephalic cells also contribute axons to the TPOC. These early generated commissural axons together with the regionally specific pattern of cell adhesion molecule expression on the optic axons may control formation of the partial retinotopic axon order in the optic tract through homophilic or heterophilic interactions that involve PSA-NCAM.

Distribution of polysialylated neural cell adhesion molecule in rat septal nuclei and septohippocampal pathway: Transient increase of polysialylated interneurons in the subtriangular septal zone during memory consolidation

During memory consolidation neuroplastic events in the mediotemporal corticohippocampal pathway are accompanied by transient increases in the frequency of neurons expressing polysialylated neural cell adhesion molecule (NCAM PSA), a posttranslational modification associated with morphofunctional change. As a bidirectional pathway between the hippocampus and the septal nuclei also influences memory processing, we have determined the distribution of NCAM PSA within this system before and after learning in the adult Wistar rat. The most intense NCAM PSA immunoreactivity was observed in the medial and triangular septal nuclei, regions that regulate hippocampal theta rhythm during memory consolidation. Within the fimbria, NCAM PSA was expressed only in a subpopulation of fibres, most likely cholinergic projections from the medial septum to the hippocampus. Grey level analysis or direct cell counting revealed no learning-specific change in NCAM PSA expression in these septal subregions after avoidance conditioning or spatial training. A population of discrete polysialylated neurons in the subtriangular septal zone, however, exhibited a transient twofold frequency increase at 12 hr after training in either task. Immunohistochemical analysis revealed these cells to be gamma-aminobutyric acid (GABAergic) interneurons co-expressing vasoactive intestinal peptide. The unique location of these interneurons is proposed to provide a natural plexus by which bidirectional communication between the septum and hippocampus may be modified during memory consolidation.

Prenatal development of the rodent rostral migratory stream

The aim of this study was to elucidate the embryological origins of the unique neuronal progenitor cells that form the rostral migratory stream (RMS), the path traversed by cells from the anterior part of the forebrain subventricular zone (SVZa) en route to the olfactory bulb. To determine when and where cells constituting the RMS initially exhibit their characteristic neuronal phenotype and high mitotic capacity, we analyzed the cells of the rat forebrain between embryonic day 14 (E14) and postnatal day 2 (P2). At E14, cells with a neuronal phenotype were observed within the ventricular zone in close proximity to the mantle layer of the future olfactory bulb. By E15, cells expressing neuronal markers are also PSA-NCAM immunoreactive and become aligned in chains of similarly oriented cells, a hallmark of the postnatal RMS. The cells that form chains organize into a patch that enlarges in the anterior-posterior and medial-lateral dimensions from E16 to E22 (birth). In comparing the forebrain cytoarchitecture to the pattern of cell type-specific staining, the patch constitutes only the central part of the proximal RMS. Early during development, the region of the RMS surrounding the patch expresses low levels of PSA-NCAM and neuron-specific markers. The proliferative activity of cells forming the patch vs. nonpatch regions of the RMS was analyzed following a short bromodeoxyuridine (BrdU) exposure. Between E15 and E22, the patch can be recognized by the mitotic activity of its cells; the cells of the patch incorporate less BrdU than the nonpatch portion of the RMS. The time course of appearance of cells forming the RMS indicates that the RMS arises in advance and independently of the cortical SVZ. Although the patch and the nonpatch regions of the embryonic RMS appear to merge postnatally, the two regions may originate separately under the influence of distinct intrinsic and extrinsic factors.

NMDA-dependent proteolysis of presynaptic adhesion molecule L1 in the hippocampus by neuropsin

Synaptic plasticity requires an activity-dependent, rapid, and long-lasting modification of synaptic character, including morphology and coupling strength. Here we show that a serine protease, neuropsin, directly and specifically modifies the synaptic adhesion molecule L1, which was localized to the presynaptic site of the asymmetric synapse in the mouse hippocampus. Increased neural activity triggered the rapid, transient activation of the precursor form of neuropsin in an NMDA receptor-dependent manner. The activated neuropsin immediately cleaved L1 and released a neuropsin-specific extracellular 180 kDa fragment. This neuropsin-specific L1-cleaving system is involved in NMDA receptor-dependent synaptic plasticity, such as the Schaffer collateral long-term potentiation.

Hemodynamics is a key epigenetic factor in development of the cardiac conduction system

The His-Purkinje system (HPS) is a network of conduction cells responsible for coordinating the contraction of the ventricles. Earlier studies using bipolar electrodes indicated that the functional maturation of the HPS in the chick embryo is marked by a topological shift in the sequence of activation of the ventricle. Namely, at around the completion of septation, an immature base-to-apex sequence of ventricular activation was reported to convert to the apex-to-base pattern characteristic of the mature heart. Previously, we have proposed that hemodynamics and/or mechanical conditioning may be key epigenetic factors in development of the HPS. We thus hypothesized that the timing of the topological shift marking maturation of the conduction system is sensitive to variation in hemodynamic load. Spatiotemporal patterns of ventricular activation (as revealed by high-speed imaging of fluorescent voltage-sensitive dye) were mapped in chick hearts over normal development, and following procedures previously characterized as causing increased (conotruncal banding, CTB) or reduced (left atrial ligation, LAL) hemodynamic loading of the embryonic heart. The results revealed that the timing of the shift to mature activation displays striking plasticity. CTB led to precocious emergence of mature HPS function relative to controls whereas LAL was associated with delayed conversion to apical initiation. The results from our study indicate a critical role for biophysical factors in differentiation of specialized cardiac tissues and provide the basis of a new model for studies of the molecular mechanisms involved in induction and patterning of the HPS in vivo.

Dynamic regulation of polysialylated neural cell adhesion molecule in the suprachiasmatic nucleus

The suprachiasmatic nucleus (SCN) prominently expresses polysialic acid (PSA), a carbohydrate polymer that is attached to neural cell adhesion molecule (NCAM) and promotes changes in cell interactions. Previous studies have shown that expression of PSA is important for circadian rhythm stability under constant darkness, and for photic entrainment of the SCN circadian clock. In the present study, immunoblot analyses of the Syrian hamster SCN revealed marked diurnal fluctuations in PSA under a 24-h light/dark cycle. PSA levels were reduced by >90% during the mid-to-late dark phase, and were elevated to maximal daytime levels approximately 1 h after lights-on. A similar pattern of PSA fluctuation persisted under constant darkness. Exposure of animals under a 24-h light/dark cycle to a 30-min light pulse during the late dark phase dramatically increased SCN contents of PSA within 60 min, and these values returned to basal levels 1-2 h later. There was no effect of light-on expression of PSA in the hippocampus. Parallel studies revealed changes in the NCAM-180 isoform that carries PSA in the brain, suggesting that regulation of PSA may include protein as well as carbohydrate-associated mechanisms. Immunohistological analysis revealed light-induced enhancement of PSA in the SCN subregion containing calbindin D(28K) cells. PSA staining was also closely associated with the majority of SCN cells expressing light-inducible Fos protein. This rhythmic, light-inducible expression of PSA within the SCN suggests that dynamic cell interactions are important for the photic regulation of circadian clock phase.

Comparative expression patterns of T-, N-, E-cadherins, beta-catenin, and polysialic acid neural cell adhesion molecule in rat cochlea during development: implications for the nature of Kölliker's organ

We investigated the expression patterns of several cell adhesion molecules (CAMs) during rat cochlea ontogeny, from embryo day 16 to adulthood, with the use of immunohistochemistry: neural cadherin (N-cad) and polysialic acid neural CAM (PSA-NCAM) as two different neural CAM paradigms; epithelial cadherin (E-cad), which was restricted to the epitheloid phenotype; and the cytoplasmic domain-free truncated-cadherin (T-cad). We made the following observations. (1) T-cad was present in all types of fibrocyte and in subdomains within the pillar cells. (2) E- and N-cad were expressed with mutually exclusive patterns and did not overlap with T-cad. All cochlear epithelial cells, including the sensory outer hair cells (OHCs), were E-cad-positive, except for the negative inner hair cells (IHCs) and the nonsensory Kölliker's organ domain close to the IHCs. N-cad expression appeared first in the developing IHCs and then in the neighboring Kölliker's organ in an increasingly mediolateral gradient in opposition to the E-cad gradient. The OHCs, which are never N-cad positive, intensively expressed E-cad, as did the Hensen cells at the beginning of their differentiation. (3) The cadherin-linked molecule beta-catenin, absent in fibrocytes, was detected in all epithelial cell membranes and was prominent in the E-cad-rich modiolar extremity of Kölliker's organ. (4) Gradual PSA-NCAM expression was observed in the lateral portion of Kölliker's organ, and the intense PSA-NCAM expression was seen surrounding the IHCs. As development proceeded, PSA-NCAM immunoreactivity progressively became restricted to the basal poles of the IHCs, where it remained in the adult rat cochlea, suggesting a synaptic plasticity. Synaptic plasticity in rat cochlea and hypotheses about T-cad functions and neosensory features of the Kölliker's organ are discussed.

Distribution and densitometry mapping of L1-CAM immunoreactivity in the adult mouse brain--light microscopic observation

BACKGROUND

The importance of L1 expression in the matured brain is suggested by physiological and behavioral studies showing that L1 is related to hippocampal plasticity and fear conditioning. The distribution of L1 in mouse brain might provide a basis for understanding its role in the brain.

RESULTS

We examined the overall distribution of L1 in the adult mouse brain by immunohistochemistry using two polyclonal antibodies against different epitopes for L1. Immunoreactive L1 was widely but unevenly distributed from the olfactory bulb to the upper cervical cord. The accumulation of immunoreactive L1 was greatest in a non-neuronal element of the major fibre bundles, i.e. the lateral olfactory tract, olfactory and temporal limb of the anterior commissure, corpus callosum, stria terminalis, globus pallidus, fornix, mammillothalamic tract, solitary tract, and spinal tract of the trigeminal nerve. High to highest levels of non-neuronal and neuronal L1 were found in the grey matter; i.e. the piriform and entorhinal cortices, hypothalamus, reticular part of the substantia nigra, periaqueductal grey, trigeminal spinal nucleus etc. High to moderate density of neuronal L1 was found in the olfactory bulb, layer V of the cerebral cortex, amygdala, pontine grey, superior colliculi, cerebellar cortex, solitary tract nucleus etc. Only low to lowest levels of neuronal L1 were found in the hippocampus, grey matter in the caudate-putamen, thalamus, cerebellar nuclei etc.

CONCLUSION

L1 is widely and unevenly distributed in the matured mouse brain, where immunoreactivity was present not only in neuronal elements; axons, synapses and cell soma, but also in non-neuronal elements.

Cerebrospinal fluid-contacting neurons in the rat spinal cord, a gamma-aminobutyric acidergic system expressing the P2X2 subunit of purinergic receptors, PSA-NCAM, and GAP-43 immunoreactivities: light and electron microscopic study

Cerebrospinal fluid-contacting neurons (CSFcNs) occur in various brain regions of lower vertebrates. In mammals, they are restricted to medullospinal areas, and little is known about their projection sites. In the present work, we investigated some morphofunctional characteristics of such neurons in the rat spinal cord by light and electron microscopic immunocytochemistry. CSFcNs expressing the P2X(2) subunit of purinergic receptors were present throughout the spinal cord, though more numerous at lower thoracolumbar and sacral levels. These neurons coexpressed GAD and the polysialylated neural cell adhesion molecule (PSA-NCAM), a marker of cellular plasticity. From low thoracic levels downward, tiny amyelinic axons (less than 200 nm in diameter) were tightly packed in bundles, which ran along the ependyma and extended ventrally, eventually concentrating against the walls of the ventral median fissure. In addition to P2X(2), GAD, gamma-aminobutyric acid (GABA), and PSA, these axons expressed GAP-43 immunoreactivity. Moreover, they were labelled along their entire lengths with antibodies against synaptotagmin and synaptophysin, but these failed to reveal intraspinal terminal fields. Taken together, our observations indicate the presence in the rat spinal cord of a highly plastic system of GABAergic CSFcNs that express the P2X(2) subunit of purinergic receptors. The function of this original system remains open to question. In these neurons, the P2X(2) receptors may confer a sensitivity to ATP either present in the CSF or released by nearby neurons of the central autonomic area.

L1 adhesion molecule (CD 171) in development and progression of human malignant melanoma

The L1 adhesion molecule (CD171) plays an important role in axon guidance and cell migration in the nervous system. In the human, L1 is expressed on tumors derived from neurocrest and on certain carcinomas. We have analyzed immunohistochemically L1 expression on paraffin embedded specimens of acquired melanocytic nevi, primary cutaneous melanomas, and cutaneous and lymph node metastases of malignant melanomas. We found an increase in L1 immunoreactivity in malignant melanomas and metastases of malignant melanomas as compared to acquired melanocytic nevi that was statistically significant (P<0.05). Additionally, a correlation of L1 immunoreactivity with histological data of prognostic value such as Clark level and the expression of alphav-integrins was found. We detected soluble L1 in the conditioned medium of cultivated melanoma cells but only in 1/40 serum samples from a panel of melanoma patients representing various stages of disease. Our findings suggest that the presence of L1 might contribute to tumor progression by promoting cell adhesion and migration.

Distribution of PSA-NCAM expression in the amygdala of the adult rat

Synaptic plasticity in the amygdala appears to be necessary for the generation of emotional memories. However, the molecular bases of this plasticity are not fully understood. Because the polysialylated form of the neural cell adhesion molecule (PSA-NCAM) has been implicated in memory consolidation in the hippocampus and temporal cortex, we have studied in detail the expression of this molecule in the adult rat amygdala with an antibody against PSA-NCAM. Our results demonstrate for the first time the presence of PSA-NCAM in the adult rat amygdala. Immunoreactive somata and processes are abundant in the amygdalo-hippocampal transition area, central nucleus, intra-amygdaloid bed nucleus of the stria terminalis, anterior and posterior cortical nuclei, periamygdaloid cortex and medial nucleus of the amygdala. In addition PSA-NCAM immunoreactive neuronal somata and processes exist in the lateral, basal and accessory basal nuclei, anterior amygdaloid area and amygdalo-striatal area. The presence of this molecule in areas that receive olfactory or vomeronasal input could reflect the intrinsic plasticity of these chemosensory systems. PSA-NCAM expression in the lateral amygdala could indicate its participation in the plastic events that lead to the generation of emotional memories such as those related to fear conditioning.

PSA-NCAM immunocytochemistry in the cerebral cortex and other telencephalic areas of the lizard Podarcis hispanica: differential expression during medial cortex neuronal regeneration

The lizard medial cortex, a region homologous to the mammalian dentate gyrus, shows postnatal neurogenesis and the surprising ability to replace its neurons after being lesioned specifically with the neurotoxin 3-acetylpyridine. As the polysialylated form of the neural cell adhesion molecule (PSA-NCAM) is expressed during neuronal migration and differentiation, we have studied its distribution in adult lizards and also during the lesion-regeneration process. In the medial cortex of control animals, many labeled fusiform somata, presumably corresponding to migratory neuroblasts, appeared in the inner plexiform layer. There were also scattered immunoreactive granule neurons in the cell layer. Double immunocytochemistry with 5'-bromodeoxyuridine revealed that some of the PSA-NCAM-expressing cells in the inner plexiform and cell layers were generated recently. PSA-NCAM immunoreactivity was also present in the dorsomedial, dorsal, and lateral cortices, as well as in the dorsal ventricular ridge, the nucleus accumbens, and the nucleus sphericus. Twelve hours after the injection of 3-acetylpyridine, some medial cortex granule neurons appeared degenerated, although some of them still expressed PSA-NCAM. One to 2 days after the injection, most granule neurons appeared degenerated and no PSA-NCAM immunoreactivity was detected in the medial cortex cell layer. Four to 7 days after treatment, abundant labeled fusiform cells populated the inner plexiform layer and some immunoreactive somata were seen in the cell layer. Fifteen to 30 days after the neurotoxin injection, the number of PSA-NCAM expressing granule neurons augmented considerably and the level was still above control levels in lizards that survived 42 days. Our results show for the first time the expression of PSA-NCAM in a reptile brain, where it appears to participate in the migration and differentiation of granule neurons during adult neurogenesis and regeneration.