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A 2-year professional master of health science program at the University of Toronto provides a unique integrated educational program to train allied health science personnel to practice as physician extenders and health care professionals in two high-demand clinical laboratory disciplines, Pathologists' Assistant (PA) and Clinical Embryologist (CE). This report describes an integrated graduate program developed and delivered in a research-intensive laboratory medicine department. The core courses in fundamental biomedical science and in general medical laboratory function and operations formed the foundation on which the requisite clinical skills required to practice as a PA or CE were subsequently delivered as comprehensive CE and PA specialty courses and practicums. Students acquired research skills through courses that teach research methods, critical analysis of research articles, and biostatistics for clinical research scientists. A capstone research project provided students the opportunity to design a research project relevant to the CE or PA fields, perform and analyze the findings, and present the project as an oral abstract and a written scientific article. Students learn to face the clinical challenges by focusing on critical analysis of evidence-based professional practice. The PA field received a 5-year accreditation. CE and PA students presented their clinical research at national and international meetings, with some receiving awards, and published scientific articles. All graduates found meaningful employment in their respective fields, and initial employer response has been favorable., Competing Interests: Disclosure Statement None declared., (Copyright © 2024 American Society for Investigative Pathology. Published by Elsevier Inc. All rights reserved.)

Renal cell carcinoma (RCC) is often diagnosed incidentally as a small renal mass (SRM; pT1a, ≤4 cm). Increasing concerns surrounding the overtreatment of patients with benign or clinically silent SRMs has resulted in a recent shift in treatment recommendations, especially in elderly and infirm patients. There are currently no biomarkers that can predict progression. We used a quantitative label-free liquid chromatography-tandem mass spectrometry peptidomics approach and targeted parallel-reaction monitoring to identify early, noninvasive diagnostic and prognostic biomarkers for early-stage RCC-SRMs. In total, 115 urine samples, including 33 renal oncocytoma (≤4 cm) cases, 30 progressive and 26 nonprogressive clear cell RCC-SRM cases, and 26 healthy controls were evaluated. Nine endogenous peptides that displayed significantly elevated expression in clear cell RCC-SRMs relative to healthy controls were identified. Peptides NVINGGSHAGNKLAMQEF, VNVDEVGGEALGRL, and VVAGVANALAHKYH showed significantly elevated expression in clear cell RCC-SRMs relative to renal oncocytoma. Additionally, peptides SHTSDSDVPSGVTEVVVKL and IVDNNILFLGKVNRP displayed significantly elevated expression in progressive relative to nonprogressive clear cell RCC-SRMs. Peptide SHTSDSDVPSGVTEVVVKL showed the most significant discriminatory utility (area under the curve, 0.76; 95% CI, 0.62-0.90; P = 0.0027). Patients with elevated SHTSDSDVPSGVTEVVVKL expression had significantly shorter overall survival (hazard ratio, 4.13; 95% CI, 1.09-15.65; P = 0.024) compared to patients with low expression. Pretreatment characterization of urinary peptides can provide insight into early RCC progression and may aid clinical decision-making and improve disease management., (Copyright © 2019 American Society for Investigative Pathology. Published by Elsevier Inc. All rights reserved.)

Objectives: microRNAs (miRNAs) are small noncoding RNAs that regulate gene expression by mRNA cleavage or translational repression. The miR-200 family is involved in the regulation of various tumor biologic processes including apoptosis, proliferation, invasion, and metastasis. They function mainly as tumor suppressors. In this study, we aim to validate the prognostic significance of miR-200 family using large cohort of primary clear cell renal cell carcinoma (ccRCC) and matched normal tissue and to explore the role of miR-200 family in RCC pathogenesis and progression., Materials and Methods: We analyzed the expression of 3 members of the miR-200 family; miR-141, miR-200b, and miR-200c, between primary ccRCC, matched normal renal tissues, and nonmatched metastatic RCC. We compared clinicopathologic parameter including disease-free survival to miR-200 family expression. Additionally, we validated our results using The Cancer Genome Atlas dataset. We explored functional role of these miRNAs by bioinformatics analyses., Results and Conclusions: Expression of miR-200 family significantly decreased in cancer compared to non-neoplastic tissues. miR-141 and miR-200b were significantly down-regulated in metastatic than primary tumors. There was statistically significant negative association between all 3 miRNAs and tumor size and stage. As binary variables, univariate analyses revealed that miR-141, miR-200b, and miR-200c-positive ccRCC patients have a statistically significant lower chance of disease-recurrence or relapse and multivariate analyses showed miR-200b and miR-200c-positive patients have longer disease-free survival. We could predict disease-free survival better when 2 or more miRNAs were used as a combination. Overall survival analysis using The Cancer Genome Atlas data revealed that miR-200b-positive patients have significantly better survival. These results suggest that miR-141, miR-200b, and miR-200c are independent prognostic markers for ccRCC. Targets of these miRNAs are associated with pathways related to cancer invasion and metastasis, including TRAIL pathway, VEGF and VEGFR signaling network, and epithelial-mesenchymal transition., (Copyright © 2019 Elsevier Inc. All rights reserved.)

Papillary renal cell carcinoma (PRCC) is the most common type of RCC in end-stage kidney disease (ESKD). Papillary adenoma (PA) is a small benign lesion morphologically similar to PRCC and is suggested to be its precursor. PA is also prevalent in ESKD. The evolution of PAs to PRCCs and their relationship to ESKD are poorly understood. A total of 140 PAs, normal kidneys, ESKDs, and PRCCs were analyzed. Previously described markers of renal tubular progenitor cells were analyzed using immunohistochemistry and quantified with digital analysis. Progenitor cells were significantly increased in ESKD (P < 0.0001) and PAs (P = 0.02) in comparison with the normal kidney. Pathway analysis using global miRNA and chromosomal copy number variations revealed a common developmental theme between PA and the PRCCs. Whole exome sequencing showed a KMT2C-specific pathogenic mutation among all PAs and PRCCs. KMT2C is a chromosome 7 epigenetic regulator implicated in development and oncogenesis. Collectively, results show possible connection of PRCCs to PA and the progenitor-like cell population, which are increased in response to renal tubular injury. In addition, each PRCC histologic subtype had its own set of mutational changes, indicating divergence from a common precursor. The study reports previously unknown biological aspects of PRCC development and could influence current surveillance criteria and early detection strategies of PRCC tumors., (Copyright © 2019 American Society for Investigative Pathology. Published by Elsevier Inc. All rights reserved.)

Platelets have long been recognized as key players in hemostasis and thrombosis; however, growing evidence suggests that they are also significantly involved in cancer, the second leading cause of mortality worldwide. Preclinical and clinical studies showed that tumorigenesis and metastasis can be promoted by platelets through a wide variety of crosstalk between platelets and cancer cells. For example, cancer changes platelet behavior by directly inducing tumor-platelet aggregates, triggering platelet granule and extracellular vesicle release, altering platelet phenotype and platelet RNA profiles, and enhancing thrombopoiesis. Reciprocally, platelets reinforce tumor growth with proliferation signals, antiapoptotic effect, and angiogenic factors. Platelets also activate tumor invasion and sustain metastasis via inducing an invasive epithelial-mesenchymal transition phenotype of tumor cells, promoting tumor survival in circulation, tumor arrest at the endothelium, and extravasation. Furthermore, platelets assist tumors in evading immune destruction. Hence, cancer cells and platelets maintain a complex, bidirectional communication. Recently, aspirin (acetylsalicylic acid) has been recognized as a promising cancer-preventive agent. It is recommended at daily low dose by the US Preventive Services Task Force for primary prevention of colorectal cancer. The exact mechanisms of action of aspirin in chemoprevention are not very clear, but evidence has emerged that suggests a platelet-mediated effect. In this article, we will introduce how cancer changes platelets to be more cancer-friendly and highlight advances in the modes of action for aspirin in cancer prevention. We also discuss the opportunities, challenges, and opposing viewpoints on applying aspirin and other antiplatelet agents for cancer prevention and treatment., (© 2018 by The American Society of Hematology.)

Clear cell renal cell carcinoma (ccRCC) is an aggressive tumor with unpredictable behavior. Clinical parameters are not always accurate for predicting prognosis. miR-126 is differentially expressed in many cancers, including RCC, and is down-regulated in metastatic versus primary ccRCC. We assessed the prognostic significance of miR-126 in 264 primary ccRCCs. We also compared its expression in normal kidney, primary and metastatic ccRCC, and RCC subtypes. We validated our results on an independent set of 481 ccRCCs. miR-126 was down-regulated in metastatic versus primary tumors and in tumors of higher stage (P = 0.005) or higher grade (P = 0.002). miR-126 up-regulation was associated with significantly prolonged disease-free survival (P < 0.001) and overall survival (P = 0.015). For larger tumors (>4 cm), patients with higher miR-126 expression had significantly longer survival. Restoration of miR-126 expression decreased cellular migration and proliferation in RCC cell lines. The ccRCCs exhibited the highest miR-126 expression, and papillary RCCs exhibited the lowest expression. We identified a number of miR-126 targets and pathways that are involved in carcinogenesis, including the apoptosis signaling pathway. miR-126 is a promising prognostic marker in ccRCC that can distinguish between clear cell and papillary subtypes. In addition, miR-126 has potential therapeutic applications., (Copyright © 2015 American Society for Investigative Pathology. Published by Elsevier Inc. All rights reserved.)

Accurate assessment of prognosis of clear cell renal cell carcinoma (ccRCC) is key in optimizing management plans to fit individual patient needs. miRNAs are short noncoding single-stranded RNAs that control the expression of target genes and may act as cancer biomarkers. We analyzed the expression of miR-210 in 276 cases of primary ccRCC and compared its expression in 40 pairs of adjacent normal and cancerous tissues. We assessed its expression in primary and metastatic tumors, in the common RCC subtypes, and the benign oncocytoma. The results were validated with an independent data set from The Cancer Genome Atlas. miR-210 was significantly overexpressed in ccRCC compared with normal kidney. miR-210(+) patients had a statistically higher chance of disease recurrence [hazard ratio (HR), 1.82; P = 0.018] and shorter overall survival (HR, 2.46; P = 0.014). In multivariate analysis, miR-210 lost its statistically significant association with shorter disease-free survival and overall survival after adjusting for tumor size and tumor, node, metastasis stage. Papillary RCC showed comparable miR-210 overexpression, whereas decreased up-regulation was seen in chromophobe RCC and oncocytoma. A number of predicted targets that might be involved in carcinogenesis and aggressive tumor behavior were identified. miR-210 is a potential therapeutic target and independent marker of poor prognosis of ccRCC., (Copyright © 2015 American Society for Investigative Pathology and the Association for Molecular Pathology. Published by Elsevier Inc. All rights reserved.)

Clear cell renal cell carcinoma (ccRCC) is the most common tumor of the adult kidney, with an increasing rate of incidence. Recently, exome sequencing studies have revealed that the SWI/SNF (switch/sucrose nonfermentable) members PBRM1 and ARID1A are mutated in ccRCC, and it has also been suggested that aberrant chromatin regulation is a key step in kidney cancer pathogenesis. Herein, we show that down-regulation of another SW/SNF component, ARID1A, occurs frequently in ccRCC. We detected copy number loss of ARID1A in 16% of patients with ccRCC. Immunohistochemistry indicated that 67% of ccRCC (53 of 79) had significantly lower expression of BAF250a, the protein product of ARID1A, than did the matched normal kidney cortex. In parallel, we conducted in silico mRNA expression analysis on 404 ccRCC tumors and 167 normal kidney cortex samples using publicly available databases and confirmed significant down-regulation of ARID1A in 68.8% of patients. We also show that decreased BAF250a protein and ARID1A mRNA expression correlate with tumor stage and grade. Our results indicate that both the protein and mRNA levels of ARID1A are statistically significant prognostic markers for ccRCC. Even after controlling for other confounders in the multivariate analysis, BAF250 retained its prognostic significance. BAF250a IHC is easy to perform and represents a potential biomarker that could be incorporated in laboratory practice to enhance the accuracy of the existing prognostic models., (Copyright © 2013 American Society for Investigative Pathology. Published by Elsevier Inc. All rights reserved.)

Renal cell carcinoma (RCC) is the most common neoplasm of the kidney. Increasing evidence suggests that microRNAs are dysregulated in RCC and are important factors in RCC pathogenesis. miR-21 is a known oncogene with tumor-promoting effects in many types of cancer. In this study, we analyzed miR-21 in 121 cases of healthy kidney and different RCC subtypes, including clear cell (ccRCC), papillary (pRCC), chromophobe (chRCC), and oncocytoma. Total RNA was extracted, and the expression of miR-21 was measured with real-time quantitative RT-PCR using miR-21-specific probes. The expression of miR-21 was significantly up-regulated in RCC compared with healthy kidney. There was a significant difference in the expression levels between RCC subtypes, with the highest levels of expression in ccRCC and pRCC subtypes. miR-21 expression distinguished ccRCC and pRCC from chRCC and oncocytoma with 90% specificity (95% CI, 63.9% to 98.1%) and 83% sensitivity (95% CI, 53.5% to 97.6%). Significantly higher miR-21 levels were associated with higher stage and grade. Patients who were miR-21 positive had statistically significant shorter disease-free and overall survival rates. Thus, miR-21 is up-regulated in RCC, and its expression levels can be used as a diagnostic marker to distinguish ccRCC and pRCC from chRCC and oncocytoma. Moreover, it has potential as a prognostic marker in RCC, although it is not independent of tumor stage and grade., (Copyright © 2012 American Society for Investigative Pathology and the Association for Molecular Pathology. Published by Elsevier Inc. All rights reserved.)

The von Hippel-Lindau (VHL) gene is lost in ≈ 70% of all renal cell carcinomas (RCCs); however, increasing evidence supports the involvement of alternative mechanisms in the regulation of VHL expression, including suppression by microRNAs (miRNAs). miRNAs are small, noncoding RNA molecules that regulate gene expression through binding to target mRNAs. In this study, we found that miRNAs, which are dysregulated in cases of RCC, can target multiple members of RCC-related signaling pathways. Importantly, both VHL and the hypoxia-inducible factor 1-α gene are experimentally validated and are likely direct targets of miR-17-5p and miR-224, as shown by both luciferase assay and Western blot analysis. We found a negative correlation between miR-17-5p and its two predicted targets, VEGF-A and EGLN3, and between miR-224 and its targets SMAD4 and SMAD5 in RCC specimens, suggesting that downstream signaling pathways are also modulated by clear cell RCC-dysregulated miRs. Results from our bioinformatics analysis show that a single miRNA molecule can target multiple components of the same pathway and that multiple miRNAs can target the same molecule. Our results also indicate that miRNAs represent a mechanism for the inactivation of VHL in cases of RCC and can elucidate a new dimension in cancer pathogenesis. As such, miRNAs exemplify new potential therapeutic targets with a significant effect on both tumor growth and metastatic potential., (Copyright © 2012 American Society for Investigative Pathology. Published by Elsevier Inc. All rights reserved.)

Background: The kallikrein family is a group of 15 serine protease genes clustered on chromosome 19q13.4. Human kallikrein gene 13 (KLK13) is a member of this family and encodes for a trypsin-like, secreted serine protease (hK13). Given that other kallikreins are sequestered by serum protease inhibitors, we hypothesized that hK13 may also interact with similar inhibitors. Our objective was to identify serum protease inhibitors that interact with human hK13., Methods: Recombinant hK13 produced in yeast was added to male and female sera and various biological fluids and the spiked samples were analyzed with an hK13 ELISA assay. Enzymatically active hK13 was 125I-labeled and used in in vitro reactions with candidate protease inhibitors and serum samples. The mixtures were then subjected to gel filtration and SDS-PAGE analysis. Candidate inhibitors were also tested in enzymatic assays of hK13 activity., Results: The recovery of recombinant hK13 from male and female sera, measured by three versions of the hK13-ELISA, ranged from 5% to 10%. The same recovery was obtained when serum samples from males and females were spiked with hK13 from amniotic fluid and seminal plasma. However, when hK13 was added to other biological fluids, such as amniotic fluid and breast milk, recovery ranged from 70% to 98%. In vitro analysis indicated that enzymatically active 125I-labeled hK13 forms SDS-stable complexes with alpha2-antiplasmin, alpha2-macroglobulin and alpha1-antichymotrypsin. When added to serum, active hK13 formed stable complexes with molecular masses corresponding to hK13 and the inhibitors mentioned above., Conclusions: hK13 interacts and forms complexes with serum protease inhibitors, including alpha2-macroglobulin, alpha1-antichymotrypsin and alpha2-antiplasmin.

Serine proteases (SP) are peptidases with a uniquely activated serine residue in the substrate-binding pocket. They represent about 0.6% of all proteins in the human genome. SP are involved in many vital functions such as digestion, blood clotting, fibrinolysis, fertilization, and complement activation and are related to many diseases including cancer, arthritis, and emphysema. In this study, we performed a genomic analysis of human serine proteases utilizing different databases, primarily that of MEROPS. SP are distributed along all human chromosomes except 18 and Y with the highest density (23 genes) on chromosome 19. They are either randomly located within the genome or occur in clusters. We identified a number of SP clusters, the largest being the kallikrein cluster on chromosome 19q13.4 which is formed of 15 adjacent genes. Other clusters are located on chromosomes 19p13, 16p13, 14q11, 13q35, 11q22, and 7q35. Genes of each cluster tend to be of comparable sizes and to be transcribed in the same direction. The members of some clusters are sometimes functionally related, e.g., the involvement of many kallikreins in endocrine-related malignancies and the hematopoietic cluster on chromosome 14. It is hypothesized that members of some clusters are under common regulatory mechanisms and might be involved in cascade enzymatic pathways. Several functional domains are found in SP, which reflect their functional diversity. Membrane-type SP tend to cluster in 3 chromosomes and have some common structural domains. Several databases are available for screening, structural and functional analysis of serine proteases. With the near completion of the Human Genome Project, research will be more focused on the interactions between SP and their involvement in pathophysiological processes.

Kallikreins are a subgroup of the serine protease family of enzymes. Until recently, it was thought that the human kallikrein gene family includes only three members. Over the past 3 years, the human kallikrein gene locus on chromosome 19q13.4 has been characterized. This family includes 15 members for which new nomenclature has been established. A number of kallikreins are expressed in the central nervous system (CNS). Experimental evidence has shown that at least two kallikreins, KLK6 and KLK8, have potential functions in the CNS. KLK8 (neuropsin) is highly expressed in brain tissues and may play a role in brain development, plasticity and response to stress. Of particular interest is the possible involvement of kallikreins in the pathogenesis of Alzheimer's disease (AD). KLK6 (zyme/protease M/neurosin) seems to be down regulated in serum and tissues of Alzheimer's disease patients and may be involved in amyloid metabolism.

Minisatellites are repetitive sequences of DNA that are present throughout the genome. Although the origin and function of these minisatellites is still unknown, they found clinical applications as markers of many diseases, including cancer. Also, they are useful tools for DNA fingerprinting and linkage analysis. Kallikreins are serine proteases that appear to be involved in many diseases including brain disorders and malignancy. We have recently characterized the human kallikrein gene locus on chromosome 19q13.4, which includes 15 kallikrein genes. In this study, we examined the kallikrein locus ( approximately 300 Kb) for all known repeat elements. About 50% of this genomic area is occupied by different repeat elements. We also identified unique minisatellite elements that are restricted to chromosome 19q13. Ten clusters of these minisatellites are distributed along the locus on either DNA strand. The clusters are located in the promoters and enhancers of genes, in introns, and in untranslated regions of the mRNA. Analysis of these elements indicates that they are polymorphic, thus they can be useful in linkage analysis and DNA fingerprinting. Our preliminary results indicate also that the distribution of the different alleles of these minisatellites might be associated with malignancy., (Copyright 2001 Academic Press.)

By using the positional candidate gene approach, we identified a novel putative serine/threonine kinase substrate gene that maps to chromosome 19q13.3. Screening of expressed sequence tags and reverse transcription-polymerase chain reaction of total RNA from human tissues allowed us to establish the expression of the gene and delineate its genomic organization (GenBank Accession No. AF200923). This gene (TSKS, for testis-specific kinase substrate) is composed of 11 exons and 10 intervening introns and is likely the human homolog of the mouse testis-specific serine kinase substrate gene. The predicted protein-coding region of the gene is 1779 bp, encoding for a 592-amino-acid polypeptide with a calculated molecular mass of 65.1 kDa. Genomic analysis of the region 19q13.3 placed the TSKS gene close to the known genes IRF3, RRAS, and alpha-Adaptin A. TSKS exhibits high levels of expression exclusively in human testicular tissue. The expression of TSKS is downregulated in cancerous testicular tissue, in comparison to adjacent normal tissue. TSKS expression was very low or undetectable in seminoma, teratocarcinoma, embryonal, and Leydig cell tumors, while high expression was observed in testicular tissue adjacent to tumors which contain premalignant carcinoma in situ. The expression of the TSKS gene was very low in two human embryonal carcinoma cell lines, 2102Ep and NTERA-2. These observations suggest a role of TSKS in testicular physiology, most probably in the process of spermatogenesis or spermiogenesis., (Copyright 2001 Academic Press.)

The sialic acid binding immunoglobulin-like lectin (Siglec) family is a recently described member of the immunoglobulin superfamily. Within this Siglec family there exists a subgroup of molecules which bear a very high degree of homology with the molecule Siglec-3 (CD33), and has thus been designated the Siglec-3-like subgroup of Siglecs. The members of this subgroup have been localized to chromosome 19q13.4, through both in situ hybridization and precise genomic mapping at the nucleotide level. Through the positional cloning approach we have identified and characterized a Siglec-like gene (SLG), a putative novel member of the Siglec-3-like subgroup of Siglecs. We have characterized the complete genomic structure of SLG, as well as two alternative splice variants, and determined its chromosomal localization. The short isoform, SLG-S, consists of seven exons, with six intervening introns, while the longer isoform, SLG-L, consists of eight exons and seven intervening introns. The SLG gene is localized 32.9 kb downstream of Siglec-8 on chromosome 19q13.4. The putative SLG-S and SLG-L proteins, of 477 and 595 amino acid residues, respectively, show extensive homology to many members of the Siglec-3-like subgroup. This high degree of homology is conserved in the extracellular Ig-like domains, as well as in the cytoplasmic tyrosine-based motifs. Interestingly, the SLG-L protein contains two N-terminal V-set Ig-like domains, as opposed to SLG-S and other Siglec-3-like subgroup members which contain only one such domain. Through RT-PCR we have examined the expression profile of both SLG splice variants in a panel of human tissues and have found that SLG-S is highly expressed in spleen, small intestine and adrenal gland, while SLG-L exhibits high levels of expression in spleen, small intestine, and bone marrow. This gene is quite likely the latest novel member of the CD33-like subgroup of Siglecs, and given its high degree of homology, it may also serve a regulatory role in the proliferation and survival of a particular hematopoietic stem cell lineage, as has been found for CD33 and Siglec7., (Copyright 2001 Academic Press.)

The sialic acid binding immunglobulin-like lectin (Siglec) family is a recently described member of the immunoglobulin superfamily. Within the Siglec family, there exists a subgroup, which bears a high degree of homology with the molecule CD33 (Siglec-3), and has thus been designated the CD33-like subgroup of Siglecs. Members of this subgroup have been localized to chromosome 19q13.4. Through the positional candidate approach, we identified a novel potential member of this subgroup of Siglecs. We have characterized the complete genomic structure of this gene, determined its chromosomal localization, its homology to other members of the Siglec family, and its tissue expression profile. This new Siglec-like gene is comprised of 11 exons, with 10 intervening introns, and is localized 278 kb telomeric to Siglec-9 and 35 kb centromeric to Siglec-8 and on chromosome 19q13.4. The coding region consists of 2094 base pairs, and encodes for a putative 76.6 kDa protein. All Siglec-conserved structural features, including V-set domain, three C-set domains, transmembrane domain, ITIM and SLAM motifs, were found in this Siglec-like gene. Also, it has the conserved amino acids essential for sialic acid binding. The Siglec-like gene has 40-66% homology with members of the CD33-like subgroup, including Siglecs 5-9. Through RT-PCR we have examined the expression profile of this new gene in a panel of human tissues and found it to be primarily expressed in the bone marrow, spleen, brain, small intestine, colon, and spinal cord. We were also able to identify three different splice variants of the new gene. This gene may represent the latest novel member of the CD33-like subgroup of Siglecs, and, given its high degree of homology, it may also serve a regulatory role in the proliferation and survival of a particular hematopoietic stem cell lineage, as has been found for CD33 and Siglec-7., (Copyright 2001 Academic Press.)

Through efforts to investigate the CD33-like subgroup of sialic acid binding immunoglobulin-like lectins (Siglecs), which are believed to be located on chromosome 19q13.4, we have identified the precise genomic region containing the Siglec8 gene. It is located on chromosome 19q13.4, approximately 330 kb downstream of the Siglec9 gene. Further, we have identified a novel Siglec8 variant, named Siglec8-Long (Siglec8-L), which differs in its last two exons from the previously published mRNA sequence of Siglec8 (GenBank Accession No. AF195092). Both Siglec8 and Siglec8-L are comprised of seven exons, of which the first five are identical, followed by marked differences in exon usage and mRNA splicing. The 499 amino acid protein encoded by the Siglec8-L open reading frame has a molecular weight of 54 kDa. Like the other members of the CD33-like subgroup of Siglecs, except for the previously published Siglec8, Siglec8-L also contains the two tyrosine-based motifs that have been found to recruit both SH2 domain-containing tyrosine and inositol phosphatases., (Copyright 2000 Academic Press.)

Kallikreins are a subgroup of serine proteases with diverse physiological functions. Recently, growing evidence indicates that many kallikrein genes are involved in malignancy. In rodents, kallikreins are encoded by a large multigene family, but in humans only three kallikreins were thought to exist. Based on the homology between the human and rodent kallikrein loci, we studied a 300 kb region of genomic sequences around the putative KLK1 gene locus on chromosome 19q13.3-q13.4. By using linear sequence information, restriction analysis, end sequencing, PCR and blotting techniques, as well as bioinformatic approaches, we were able to construct the first detailed map of the human kallikrein gene family. Comparative analysis of genes located in this area, provides strong evidence that the human kallikrein gene family locus on chromosome 19 is considerably larger than previously thought, containing at least fifteen genes. We have established, for the first time, the common structural features that apply to all members of the expanded kallikrein multigene family. Our map specifies the distance between genes to one base pair accuracy, the relative location, and the direction of transcription of all 15 genes. Determination of the true size of the kallikrein family in humans is important for our understanding of the contribution of the kallikreins to human biology and pathophysiology., (Copyright 2000 Academic Press.)