Purification, cloning, and expression of human plasma hyaluronidase

Hyaluronidase can modulate expression of CD44

CD44 is a family of transmembrane glycoproteins with multiple isoforms generated by alternative exon splicing of a single gene. CD44 and its variants are expressed on a wide variety of cells including cancer cells. The mechanisms by which splice variant exons are selected are unknown. The presence of hyaluronan in the environment of the cell appears to influence that selection process. The expression of particular splice variants of CD44 as well as the simultaneous presence of hyaluronan is important for motility, invasion, and the metastatic spread of some tumors. The influence of hyaluronidase digestion on the expression of CD44 in human cancer cell lines was examined. CD44 isoforms containing alternatively spliced exons were sensitive to hyaluronidase digestion in all lines examined, but differences between cell lines were observed. Expression of CD44s, the standard form, was resistant to digestion in two of three cell lines. A tentative model was formulated proposing that CD44 isoforms containing splice variants are unstable, requiring the continuous presence of ligand for expression. CD44s is relatively more stable, not requiring the continuous presence of hyaluronan. Additionally, a number of new CD44 variant isoforms, not previously observed, were identified.

Stromal and epithelial expression of tumor markers hyaluronic acid and HYAL1 hyaluronidase in prostate cancer

Hyaluronic acid (HA), a glycosaminoglycan, regulates cell adhesion and migration. Hyaluronidase (HAase), an endoglycosidase, degrades HA into small angiogenic fragments. Using an enzyme-linked immunosorbent assay-like assay, we found increased HA levels (3-8-fold) in prostate cancer (CaP) tissues when compared with normal (NAP) and benign (BPH) tissues. The majority ( approximately 75-80%) of HA in prostate tissues was found to exist in the free form. Primary CaP fibroblast and epithelial cells secreted 3-8-fold more HA than respective NAP and BPH cultures. Only CaP epithelial cells and established CaP lines secreted HAase and the secretion increased with tumor grade and metastasis. The pH activity profile and optimum (4.2; range 4.0-4.3) of CaP HAase was identical to the HYAL1-type HAase present in human serum and urine. Full-length HYAL1 transcript and splice variants were detected in CaP cells by reverse transcriptase-polymerase chain reaction, cloning, and sequencing. Immunoblotting confirmed secretion of a approximately 60-kDa HYAL1-related protein by CaP cells. Immunohistochemistry showed minimal HA and HYAL1 staining in NAP and BPH tissues. However, a stromal and epithelial pattern of HA and HYAL1 expression was observed in CaP tissues. While high HA staining was observed in tumor-associated stroma, HYAL1 staining in tumor cells increased with tumor grade and metastasis. The gel-filtration column profiles of HA species in NAP, BPH, and CaP tissues were different. While the higher molecular mass and intermediate size HA was found in all tissues, the HA fragments were found only in CaP tissues. In particular, the high-grade CaP tissues, which showed both elevated HA and HYAL1 levels, contained angiogenic HA fragments. The stromal-epithelial HA and HYAL1 expression may promote angiogenesis in CaP and may serve as prognostic markers for CaP.

Plasma hyaluronidase (Hyal-1) promotes tumor cell cycling

Paradoxically, both hyaluronan (HA) and hyaluronidase are involved in malignant transformation and cancer progression. Their mechanisms of action, given the apparent disparities, are not understood. In many malignancies, levels of HA correlate with metastatic behavior while hyaluronidases suppress malignant progression. Hyal-1, product of one of six paralogous hyaluronidase-like sequences, is the predominant circulating hyaluronidase. HYAL1, the gene that codes for Hyal-1, is located on chromosome 3p21.3, a region containing a tumor suppressor gene. Loss of HYAL1 often correlates with tumor progression, particularly in tobacco-related cancers. In other malignancies, however, hyaluronidase functions as a tumor promoter. Testicular hyaluronidase (PH-20), used as an adjuvant in chemotherapy, is assumed to enhance drug permeability. By an unknown mechanism, hyaluronidases recruit tumor cells back into the cycling pool, making these malignancies more sensitive to chemotherapeutic drugs. Such contradictory observations might be resolved by assuming that HA and hyaluronidase are required at different times in the multiple steps that lead to malignant transformation. We have undertaken a systematic investigation of their roles in cancer progression. Here, we investigate the effect of Hyal-1 expression on cell cycle kinetics. A tumor cell line was constructed with an ecdysone-inducible promoter located upstream from the cDNA of HYAL1. Fluorescent-activated cell sorting was used to monitor cell cycle kinetics following Hyal-1 induction. Enhanced cell cycling was observed, with a 13.6% increase in S phase and 9.6% decrease in G(1)/G(0) phase cells.

Reverse hyaluronan substrate gel zymography procedure for the detection of hyaluronidase inhibitors

Little is known of the ubiquitous inhibitors of hyaluronidase, molecules that may be important for the deposition of hyaluronan. A reverse hyaluronan-substrate gel procedure is described here that detects such inhibitors, even in crude biological extracts, and is independent of the catalytic mechanism of the target enzyme. Following electrophoresis, hyaluronan-containing gels are incubated in a hyaluronidase solution. Alcian blue-staining bands indicate hyaluronan protected from degradation and the location of hyaluronidase inhibitors. Coordinated use of hyaluronan substrate gel and reverse substrate gel procedures provides estimates of the number and relative molecular sizes of both enzymes and their inhibitors.

Crystal structure of hyaluronidase, a major allergen of bee venom

BACKGROUND

Hyaluronic acid (HA) is the most abundant glycosaminoglycan of vertebrate extracellular spaces and is specifically degraded by a beta-1,4 glycosidase. Bee venom hyaluronidase (Hya) shares 30% sequence identity with human hyaluronidases, which are involved in fertilization and the turnover of HA. On the basis of sequence similarity, mammalian enzymes and Hya are assigned to glycosidase family 56 for which no structure has been reported yet.

RESULTS

The crystal structure of recombinant (Baculovirus) Hya was determined at 1.6 A resolution. The overall topology resembles a classical (beta/alpha)(8) TIM barrel except that the barrel is composed of only seven strands. A long substrate binding groove extends across the C-terminal end of the barrel. Cocrystallization with a substrate analog revealed the presence of a HA tetramer bound to subsites -4 to -1 and distortion of the -1 sugar.

CONCLUSIONS

The structure of the complex strongly suggest an acid-base catalytic mechanism, in which Glu113 acts as the proton donor and the N-acetyl group of the substrate is the nucleophile. The location of the catalytic residues shows striking similarity to bacterial chitinase which also operates via a substrate-assisted mechanism.

A developmentally regulated hyaluronidase of Haemonchus contortus

The trichostrongylid nematode Haemonchus contortus released a hyaluronic acid-degrading enzyme during in vitro development from the third (L3) to fourth (L4) larval stage. The enzyme did not degrade chondroitin sulfate A. Enzyme activity was optimal between pH 4.0 and 6.0, and the enzyme was inhibited by high concentrations of NaCl; the divalent cations Cu2+, Zn2+, Ca2+, and Mn2+ were not inhibitory. The hyaluronidase had a molecular mass estimated at 57 kDa by sucrose density gradient centrifugation and at 111 kDa by substrate sodium dodecyl sulfate polyacrylamide gel electrophoresis (reducing and nonreducing conditions), suggesting the formation of a dimer during the electrophoretic separation conditions. The level of hyaluronidase released during in vitro development peaked between 24 and 48 hr in culture and then gradually decreased, with little or no activity present in the 168-hr culture fluid. The enzyme was not detected in culture fluid from 24-hr incubations of either the mid-L4 stage (obtained from sheep 7 days postinfection) or the adult stage (obtained from sheep 30-35 days postinfection). The temporal expression of the hyaluronidase suggested a role for this enzyme in the early stages of the L3-L4 developmental process.

Human hyaluronidases: electrophoretic multiple forms in somatic tissues and body fluids. Evidence for conserved hyaluronidase potential N-glycosylation sites in different mammalian species

Some properties of the multiple forms of human hyaluronidases in somatic tissues and in body fluids were investigated. Liver and placenta exhibited seven hyaluronidase forms when analyzed electrophoretically on a polyacrylamide-hyaluronan gel. Ovary, breast, myometrium, endometrium, skin, leukocytes and platelets displayed distinct patterns of enzymatic micropolydispersity. The most acidic forms of hyaluronidase were in synovial fluid and serum, some serum exhibited an additional basic form. Following sialidase treatment, the number of forms decreased to two in placenta, three in liver and to a broad basic form in serum. The native serum and placental hyaluronidases remained fully active after thermal inactivation but desialylated hyaluronidase was inactivated slowly in serum, and quickly in placenta suggesting a higher overall glycosylation of the plasma enzyme. Potential N-glycosylation sites were searched in the amino acid sequences of six human hyaluronidases and several hyaluronidases from different mammalian species using the PROSITE motif database. A potential N-glycosylation site (site 1) with similar tripeptide patterns was observed at the same position in human plasma (HYAL1), human lysosomes (HYAL2) and in two newly reported hyaluronidases (HYAL4 and HYALP1). The same site was also present in mouse plasma (HYAL1) and mouse lysosomes (HYAL2), and in rat lysosomes (HYAL2). This site was absent in human HYAL3 and in all sperm hyaluronidases (PH-20) studied (human, macaque, mouse, guinea pig, rabbit and fox). A second potential N-glycosylation site was observed at a location further in the polypeptide chain. This site is present in all mammalian hyaluronidase isoenzymes reported in the present study whatever the species and organ localization. The pattern at site 2 is NVT for all hyaluronidases except for hyaluronidases of lysosomal origin where it is NVS. Such conserved sites strongly suggest that they may represent actual N-glycosylation sites.

Irradiation-induced expression of hyaluronan (HA) synthase 2 and hyaluronidase 2 genes in rat lung tissue accompanies active turnover of HA and induction of types I and III collagen gene expression

Hyaluronan (HA) is a linear glycosaminoglycan that accumulates in the interstitium of injured lung and inhibits gas exchange between air and blood. In the present study we investigated the molecular mechanisms behind the local turnover of HA during the early phase of irradiation-evoked lung fibrosis in rats. Irradiation with a single dose of 30 Gy to the lower part of the right lung of rats induced an accumulation of HA in bronchoalveolar lavage fluid 6 wk after irradiation, followed by return to almost normal levels at 10 wk after irradiation. This was parallelled with a transient downregulation of HA receptors on alveolar macrophages (AMs); 4 and 6 wk after irradiation the binding of [(3)H]HA to AMs was decreased to about 50% of that of AMs from nonirradiated control rats, returning to almost normal level at 10 wk after irradiation. Analysis of the expression of rat HA synthase (HAS) isoforms (rHAS1, rHAS2, and rHAS3) and rat hyaluronidases (rHYAL1 and rHYAL2) by Northern blotting revealed an upregulation of rHAS2 messenger RNA at 4, 6, and 10 wk after irradiation, but a progressive decrease in the constitutive expression of rHYAL2 at 6 and 10 wk after irradiation; rHAS1 was undetectable, whereas rHAS3 and rHYAL1 were faintly detectable. Although transforming growth factor-beta1 stimulated HA production by normal lung fibroblasts, it inhibited HYAL activity in lysosomes and HYAL activity released into the culture media. Another interesting observation was that HA fragments, which likely result from the action of HYAL, induced expression of types I and III collagen genes. Our results indicate that rHAS2 and rHYAL2 are involved in the turnover of HA during the early phase of lung injury and that rHAS2 and rHYAL2 as well as HA fragments may play important roles in the pathogenesis of lung fibrosis.

Distribution of renal medullary hyaluronan in lean and obese rabbits

BACKGROUND

Obese individuals have an expanded interstitium in the renal inner medulla (IM), which stains positively with periodic acid-Schiff and Alcian blue. In obese dogs, the IM is also expanded, with hyaluronan (HA) content being 2.4 times control.

METHODS

We determined the anatomic pattern of renal HA deposition following weight gain, using an animal model of obesity consisting of young rabbits (N = 10), representing animals entering into the study, lean rabbits (N = 19), fed a control diet, and obese rabbits (N = 19), fed a high-fat diet (15% fat, by fortifying with corn oil and lard, in a ratio of 2:1) for two to three months. Tissue was papain digested, and HA was recovered in a phosphate or a Tris buffer and detected by an indirect immunoabsorbent competition assay.

RESULTS

Rabbits fed a high-fat diet for 8 to 12 weeks gained weight (37%) and became mildly hypertensive (10 mm Hg). In lean rabbits, HA was low in the renal cortex (6 +/- 30 microg/g tissue), increased steadily across the outer medulla (OM; 79 +/- 28 microg/g tissue) and was uniformly high in the IM (192 +/- 28 microg/g tissue) when recovered in a Tris buffer; these levels of tissue HA did not change during the three-month period of dietary intervention. In obese rabbits, the renal medullary interstitium was expanded and stained intensely with periodic acid Schiff and Alcian blue, and tissue HA was elevated in the IM (448 +/- 25 microg/g tissue) but not the cortex (5 +/- 25 microg/g tissue) or the OM (85 +/- 25 microg/g tissue). The significant difference was due to those IM samples taken from the renal papilla; IM samples from the body of the kidney did not significantly differ among the lean, obese, and young rabbits.

CONCLUSION

The elevated renal HA associated with weight gain is limited to the IM and occurs most consistently in the papilla, which is the region of the kidney that is most vulnerable to distention caused by elevated renal interstitial hydrostatic pressure.

HYAL1LUCA-1, a candidate tumor suppressor gene on chromosome 3p21.3, is inactivated in head and neck squamous cell carcinomas by aberrant splicing of pre-mRNA

The hyaluronidase first isolated from human plasma, Hyal-1, is expressed in many somatic tissues. The Hyal-1 gene, HYAL1, also known as LUCA-1, maps to chromosome 3p21.3 within a candidate tumor suppressor gene locus defined by homozygous deletions and by functional tumor suppressor activity. Hemizygosity in this region occurs in many malignancies, including squamous cell carcinomas of the head and neck. We have investigated whether cell lines derived from such malignancies expressed Hyal-1 activity, using normal human keratinocytes as controls. Hyal-1 enzyme activity and protein were absent or markedly reduced in six of seven carcinoma cell lines examined. Comparative genomic and fluorescence in situ hybridization identified chromosomal deletions of one allele of HYAL1 in six of seven cell lines. Initial RT - PCR analyses demonstrated marked discrepancies between levels of HYAL1 mRNA and protein. Despite repeated sequence analyses, no mutations were found. However, two species of transcripts were identified when primers were used that included the 5' untranslated region. The predominant mRNA species did not correlate with protein translation and contained a retained intron. A second spliced form lacking this intron was found only in cell lines that produced Hyal-1 protein. Inactivation of HYAL1 in these tumor lines is a result of incomplete splicing of its pre-mRNA that appears to be epigenetic in nature. Oncogene (2000) 19, 870 - 877.

Topical hyaluronidase decreases hyaluronic acid and CD44 in human skin and in reconstituted human epidermis: evidence that hyaluronidase can permeate the stratum corneum

Hyaluronic acid (HA), a high molecular weight glycosaminoglycan of the extracellular matrix involved in growth, inflammation and wound healing, also contributes to the hydration and plastic properties of skin. Several drug and cosmetic formulations contain HA. We have initiated investigations that explore whether it is possible, by topical application, to modulate endogenous HA levels in skin. We developed a model epidermal culture system that exhibited a differentiated stratum corneum, and expressed HA and the HA receptor CD44, in a pattern similar to that observed in intact skin. Such in vitro skin equivalents are useful models for investigating the effect of topical drugs. HA and bacterial hyaluronidase were applied to the in vitro skin equivalent and to human skin. Their effects on endogenous HA and CD44 expression were examined using histochemical analysis. Topical HA treatment had no significant effect on HA or CD44 expression in either system. However, hyaluronidase decreased HA and CD44 expression in a dose-dependent manner in both the epidermal culture system and in skin. Apparently, HA is not able to permeate the epidermal culture system or human skin to a significant degree, but bacterial hyaluronidase does permeate both human skin and the culture system, depleting HA and decreasing CD44 expression. These effects were more prominent in the dermal than in the epidermal layers, suggesting that marked differences in HA metabolism exist in these two skin compartments. The ability of hyaluronidase to permeate the stratum corneum suggests that topical application may, additionally, be useful as a clinical modality.

HA-HAase urine test. A sensitive and specific method for detecting bladder cancer and evaluating its grade

Hyaluronic acid and HAase are intricately associated with the biology of bladder tumor angiogenesis and metastasis. Tumor-associated HA and HAase are secreted in urine. In G2 and G3 bladder tumors, HA is degraded by HAase, resulting in the generation of angiogenic HA fragments, which, in turn, are secreted in urine. An elevated urinary HA level (> or = 500 ng/mg), indicating a positive HA test, suggests the presence of bladder cancer regardless of tumor grade. The urinary HAase levels correlate with the malignant potential of bladder cancer and are elevated (> or = 10 mU/mg) in the urine of patients with G2 and G3 bladder cancer. Combining the results from the HA and the HAase tests (the HA-HAase test) yields inferences, including the detection of bladder cancer and the evaluation of its grade. The overall 92% sensitivity of the HA-HAase test to detect bladder cancer is higher than the sensitivity of individual tests with little compromise in specificity. The HA-HAase test is equally sensitive for monitoring tumor recurrence. When compared with existing noninvasive tests, the HA-HAase test may be significantly less expensive and more accurate.

Urinary hyaluronic acid and hyaluronidase: markers for bladder cancer detection and evaluation of grade

PURPOSE

Specific patterns of progression and frequent recurrence of bladder tumors determine the choice of treatment, frequency of surveillance, quality of life, and ultimately, patient prognosis. The prognosis would be improved if an accurate noninvasive test was available for diagnosis. Identification of markers that function in bladder cancer progression would be helpful in designing such diagnostic tests. The glycosaminoglycan, hyaluronic acid (HA), promotes tumor metastasis. Hyaluronidase (HAase), an endoglycosidase, degrades HA into small fragments that promote angiogenesis. We have previously shown that both HA and HAase are associated with bladder cancer and may function in bladder tumor angiogenesis. In this study we examined whether urinary HA and HAase levels serve as bladder cancer markers.

MATERIALS AND METHODS

Among the 513 urine specimens analyzed, 261 were from transitional cell carcinoma (TCC) patients, 9 from patients with non-TCC tumors, and 243 from controls (normals, patients with other genitourinary (GU) conditions or a history of bladder cancer (HxBCa)). The urinary HA and HAase levels were measured by two ELISA-like assays that utilize a biotinylated HA binding protein for detection. These levels were normalized to total urinary protein and were expressed as ng./mg. (HA test) and mU/mg. (HAase test), respectively.

RESULTS

The urinary HA levels were elevated (2.5 to 6.5 fold) in bladder cancer patients (1173.7+/-173.4; n = 261) as compared with normals (246.1+/-38.5; n = 41); GU patients (306.6+/-32.2; n = 133), and patients with a HxBCa (351.1+/-49.1; n = 69) (p <0.001). The urinary HAase levels were elevated (3 to 7 fold) in G2/G3 bladder cancer patients (26.2+/-3.2) as compared with normals (4.5+/-0.9) and patients with either GU conditions (5.8+/-1.3), HxBCa (8.2+/-2.6) or G1 tumors (9.7+/-2.5) (p <0.001). The HA test showed 83.1% sensitivity, 90.1% specificity and 86.5% accuracy in detecting bladder cancer, regardless of the tumor grade. The HAase test showed 81.5% sensitivity, 83.8% specificity and 82.9% accuracy to detect G2/G3 patients. Combining the inferences of the HA and HAase tests (HA-HAase test) resulted in detection of bladder cancer, regardless of tumor grade and stage, with higher sensitivity (91.2%) and accuracy (88.3%), and comparable specificity (84.4%).

CONCLUSION

Our results show that the HA-HAase urine test is a noninvasive, highly sensitive and specific method for detecting bladder cancer and evaluating its grade.

Hyaluronidase expression in human skin fibroblasts

Hyaluronidase activity has been detected for the first time in normal human dermal fibroblasts (HS27), as well as in fetal fibroblasts (FF24) and fibrosarcoma cells (HT1080). Enzymatic activity was secreted predominantly into the culture media, with minor amounts of activity associated with the cell layer. In both classes of fibroblasts, hyaluronidase expression was confluence-dependent, with highest levels of activity occurring in quiescent, post-confluent cells. However, in the fibrosarcoma cell cultures, expression was independent of cell density. The enzyme had a pH optimum of 3.7 and on hyaluronan substrate gel zymography, activity occurred as a single band corresponding to an approximate molecular size of 57 kDa. The enzyme could be immunoprecipitated in its entirety using monoclonal antibodies raised against Hyal-1, human plasma hyaluronidase. PCR confirmed that fibroblast hyaluronidase was identical to Hyal-1. The conclusion by previous investigators using earlier technologies that fibroblasts do not contain hyaluronidase activity should be reevaluated.

Inhibition of hyaluronidase by fully O-sulfonated glycosaminoglycans

We report a new flow injection assay (FIA) method for determining hyaluronidase activity and the inhibitory effects of chemical fully O-sulfonated glycosaminoglycans on this enzyme. The products of enzymatic action on hyaluronidase can be detected by FIA using fluorometric detection with the fluorogenic reagent 2-cyanoacetamide. The major products derived from hyaluronan by the action of mammalian testicular hyaluronidase (a hydrolyase) were confirmed by (1)H NMR spectroscopy and capillary electrophoresis. The FIA method was next applied to the assay of hyman urinary hyaluronidase activity and the screening of hyaluronidase inhibitors. The human urinary hyaluronidase activity measured ranged from 46 to 59 turbidity reducing units/mg protein. Among the glycosaminoglycans only heparin showed hyaluronidase inhibition. Chemically O-sulfonated glycosaminoglycans showed IC(50) values of hyaluronidase inhibition that correlated with the degree of O-sulfonation. Heparin was found to inhibit hyaluronidase activity noncompetitively, while chemically O-sulfonated HA strongly inhibited hyaluronidase through both competitive and noncompetitive effects.

Expression analysis of six paralogous human hyaluronidase genes clustered on chromosomes 3p21 and 7q31

Two new members of a family of putative hyaluronidase genes involved in glycosaminoglycan catabolism have been identified and mapped by FISH and YAC library screening to chromosome 7q31.3. One of these (HYALP1) is an expressed pseudogene with mutations in the genomic DNA and cDNA. The six members of the hyaluronidase family are grouped into two tightly linked triplets on human chromosomes 3p21.3 (HYAL1, HYAL2, and HYAL3) and 7q31.3 (HYAL4, SPAM1 (PH-20), and HYALP1). This arrangement could arise by an ancient cluster formation, followed by a more recent cluster block-duplication. All of the hyaluronidase genes have unique tissue-specific expression patterns as determined by Northern blot analysis of 23 human tissues. HYAL1, HYAL2, and HYALP1 are widely expressed, but HYAL3 is differentially expressed in bone marrow and testis, while HYAL4 is differentially expressed in placenta and skeletal muscle. SPAM1 (PH-20) was detectable only in testis by Northern blot as previously reported, but was detectable in fetal and placental cDNA libraries by PCR, suggesting a possible role for this gene during embryonic development.

Identification of linear surface epitopes on the guinea pig sperm membrane protein PH-20

The sperm plasma membrane protein PH-20 has previously been shown to be an effective immunogen for protection against fertilization in guinea pigs. To identify immunodominant regions on gpPH-20 that may be related to this contraceptive effect, we used several high-titer immune sera obtained from animals rendered infertile by gpPH-20 injections to screen a set of overlapping peptides that cover the entire 494-residue sequence. Multiple clusters of peptide sequences exhibited specific reactivity. Some of these sequences were then constructed as octameric synthetic peptides and tested for immunogenicity in female guinea pigs. Our results indicated two regions (res. 94-119 and res. 424-444) to be highly immunogenic and both are surface accessible when native gpPH-20 is in solution or anchored on sperm surface. Both anti-peptide antibodies are specific for gpPH-20 and one of them inhibited hyaluronidase activity partially. These monospecific antibodies should be useful probes for further molecular definition of gpPH-20 structure-function relationships.

Mutations in HYAL1, a member of a tandemly distributed multigene family encoding disparate hyaluronidase activities, cause a newly described lysosomal disorder, mucopolysaccharidosis IX

Hyaluronan (HA), a large glycosaminoglycan abundant in the extracellular matrix, is important in cell migration during embryonic development, cellular proliferation, and differentiation and has a structural role in connective tissues. The turnover of HA requires endoglycosidic breakdown by lysosomal hyaluronidase, and a congenital deficiency of hyaluronidase has been thought to be incompatible with life. However, a patient with a deficiency of serum hyaluronidase, now designated as mucopolysaccharidosis IX, was recently described. This patient had a surprisingly mild clinical phenotype, including notable periarticular soft tissue masses, mild short stature, an absence of neurological or visceral involvement, and histological and ultrastructural evidence of a lysosomal storage disease. To determine the molecular basis of mucopolysaccharidosis IX, we analyzed two candidate genes tandemly distributed on human chromosome 3p21.3 and encoding proteins with homology to a sperm protein with hyaluronidase activity. These genes, HYAL1 and HYAL2, encode two distinct lysosomal hyaluronidases with different substrate specificities. We identified two mutations in the HYAL1 alleles of the patient, a 1412G --> A mutation that introduces a nonconservative amino acid substitution (Glu268Lys) in a putative active site residue and a complex intragenic rearrangement, 1361del37ins14, that results in a premature termination codon. We further show that these two hyaluronidase genes, as well as a third recently discovered adjacent hyaluronidase gene, HYAL3, have markedly different tissue expression patterns, consistent with differing roles in HA metabolism. These data provide an explanation for the unexpectedly mild phenotype in mucopolysaccharidosis IX and predict the existence of other hyaluronidase deficiency disorders.

Expression pattern of a novel hyaluronidase during Xenopus embryogenesis

We have isolated a cDNA encoding a novel hyaluronidase, which is expressed during embryogenesis. The encoded protein was expressed as a fusion polypeptide with glutathione S-transferase, and the affinity-purified fusion protein was shown to possess hyaluronidase activity with a pH optimum about pH 4.0. The expression of the XEH1 gene was analysed by in situ hybridization, and was first apparent in scattered cells in a broad ventral region of late gastrula embryos. As development proceeded through to tailbud stages, the domain of expression became progressively more restricted, eventually being located in the developing liver rudiment near the primary hepatic cavity. The results reveal the dynamic regulation of the contrasting activities of hyaluronan synthesis and degradation during early morphogenetic movements.

Novel immunogenic antigen homologous to hyaluronidase in meningioma

By screening a meningioma expression library with autologous serum we identified four cDNA clones representing a novel gene with striking homology to Caenorhabditis elegans hyaluronidase as indicated by BLASTP analysis. In humans hyaluronidase has been implicated in cancer development and three human genes are known to encode proteins with hyaluronidase activity. None of the human genes, however, showed any homology at the nucleotide or amino acid sequence level to the newly isolated antigen we termed meningioma expressed antigen 5 (MGEA5). Somatic cell hybrid mapping and fluorescence in situ hybridization mapped the gene for MGEA5 to chromosomal band 10q24.1-q24.3. Reverse transcription (RT)-PCR and northern blot hybridization revealed expression of the gene encoding MGEA5 in several meningioma and additional human tissues. Expression analysis also indicated an alternative splicing event giving rise to a shorter and altered transcript termed MGEA5s. The expression of MGEA5 and MGEA5s as fusion proteins revealed an approximate molecular weight of 92 and 54 kDa, respectively. Using heterologous sera we found antibodies against MGEA5s in five out of 23 meningioma patients, whereas no immune reaction was detected in 12 control sera from healthy individuals. Confirmation of hyaluronidase activity was independently achieved by turbidometric analysis and a gel matrix assay. A model for involvement of the novel hyaluronidase gene in meningioma development is proposed.

Expression and activity of articular cartilage hyaluronidases

The glycosaminoglycan hyaluronan is an important component of the extracellular matrix of articular cartilage, contributing to both the structural and functional integrity of this highly specialized tissue. Hyaluronan is known to be synthesized and turned over by the resident chondrocytes, although the mechanisms involved in hyaluronan degradation are not precisely defined. Recently, the cDNA sequences of extracellular hyaluronidases present on spermatazoa and in human serum have been reported, and we have utilized these data to investigate the expression and activity of these and/or related enzymes by articular cartilage chondrocytes. By using "gene-homology" RT-PCR techniques, three hyaluronidase isozymes were found to be expressed by chondrocytes, and hyaluronidase activity was detected in cell membrane extracts and conditioned media from chondrocyte monolayer cultures following acidification to pH 4.5 or pH 3.7. In addition, the levels of mRNA for two of the chondrocyte hyaluronidases were upregulated by IL-1 and TNF stimulation, thereby implicating cartilage-derived hyaluronidase activity as a factor contributing to cytokine-induced extracellular matrix degradation during synovial joint disease.

Structural organization and chromosomal localization of Hyal2, a gene encoding a lysosomal hyaluronidase

The human HYAL2 gene encodes a lysosomal hyaluronidase that is related to the testicular PH-20 hyaluronidase. Regions conserved in these proteins have been used to design PCR primers suitable for the isolation of a fragment of the murine Hyal2 gene. This fragment was used to isolate the Hyal2 cDNA from a cDNA library. The cloned cDNA has an open reading frame of 473 codons and a 3'-untranslated region of 302 bases plus a poly(A) tail. Using this cDNA, the corresponding genomic DNA was characterized from 129SVJ mice. The murine Hyal2 gene is approximately 3.5 kb, contains the coding sequence for the mRNA on four exons, and is localized on chromosome 9 between the microsatellite markers D9Mit183 and D9Mit17 near the genes for dystroglycan and transferrin. The gene is expressed ubiquitously, the sole exception being adult brain.

Hyaluronidase and its substrate hyaluronan: biochemistry, biological activities and therapeutic uses

This is an overview of the biochemistry, biological function and therapeutic uses of hyaluronidase and its substrate, hyaluronate. We focus on the role of hyaluronate and its receptor CD44 in cell-cell and cell-matrix adhesion and cell activation as well as on the putative role of hyaluronate and hyaluronidase in morphogenesis. Variants of CD44 and their putative role in tumor metastasis are also included. Other topics that are discussed are the chemical and enzymatic nature of hyaluronidase, i.e. the mode of substrate degradation, pharmacodynamical and pharmacokinetic aspects of this enzyme and its role as spreading factor. Purification methods, possible contaminations and techniques of activity determinations are mentioned as well as the physiological role of hyaluronidase and tumor-associated alterations in serum and tissue enzyme levels. As far as therapeutic applications are concerned, we discuss uses of hyaluronidase in ophthalmology and regional anesthesia as well as pain management in osteoarthritis using hyaluronate.

Secretion of bladder tumor-derived hyaluronidase activity by invasive bladder tumor cells

Hyaluronic acid (HA), a glycosaminoglycan, promotes tumor metastasis and its small fragments are angiogenic. These small fragments are generated by degradation of HA by hyaluronidase (HAase). We measured urinary HAase levels of 196 individuals using an ELISA-like assay. The urinary HAase levels (31.1 +/- 3.7 mU/mg) of intermediate (G2) to high-grade (G3) bladder cancer patients are five- to seven-fold elevated as compared to those of normal individuals and patients with other genitourinary conditions or low-grade (G1) bladder cancer. The increase in urinary HAase levels is due to the secretion of a tumor-derived HAase which is elevated eight-fold in G2/G3 tumor tissues. The HAase in bladder tumor tissues is secreted by tumor epithelial cells and is associated with the invasive/metastatic potential of the tumor cells.

HYAL2, a human gene expressed in many cells, encodes a lysosomal hyaluronidase with a novel type of specificity

Using Expressed Sequence Tags (ESTs) deposited in the data banks, a cDNA has been assembled that encodes a protein related to the hyaluronidases from bee venom and mammalian sperm. Expression of this cDNA yielded a polypeptide termed HYAL2, which is located in lysosomes. The HYAL2 protein was shown to have hyaluronidase activity below pH 4. However, it only hydrolyzed hyaluronan of high molecular mass from umbilical cord, rooster comb, and a Streptococcus strain. The reaction product was a polysaccharide of about 20 kDa, which was further hydrolyzed to small oligosaccharides by the sperm hyaluronidase. Conversely, hyaluronan fragments from vitreous humor, which had a molecular mass of about 20 kDa, were not cleaved by the HYAL2 enzyme to any detectable extent. These results provide evidence for the existence of structural domains in hyaluronan, which are resistant to the action of this enzyme. The structural and functional implications of these findings are discussed.

The hyaluronidase gene HYAL1 maps to chromosome 3p21.2-p21.3 in human and 9F1-F2 in mouse, a conserved candidate tumor suppressor locus

We recently cloned and expressed the major hyaluronidase activity from human plasma, HYAL1, and found that the protein is 40% identical to the testicular hyaluronidase, PH-20. The HYAL1 mRNA sequence was used in a homology search of the mouse database of expressed sequence tags (dbEST). Two ESTs were obtained and, in combination with 5'RACE-PCR, were used to clone the mouse HYAL1 ortholog (Hyal1). Hyal1 codes for a protein of 462 amino acids that is 73% identical to the human sequence. Hyal1 stably expressed in human embryonic kidney cells resulted in a 20,000-fold increase of hyaluronidase activity. Sequence-tagged sites derived from the HYAL1 gene from both species were used to isolate P1 genomic clones that were used as probes for fluorescence in situ hybridization. The human gene was localized to chromosome 3p21 and the mouse gene to a syntenic region on chromosome 9F1-F2. In mouse, serum hyaluronidase polymorphism has previously been mapped by an interspecific backcross to 60 cM from the centromere of chromosome 9, which corresponds to a cytogenetic location of 9F1-F2. The mouse Hyal1 gene is therefore very likely to be responsible for the hyaluronidase polymorphism linked to this locus. We also present evidence that human HYAL1 is identical to an uncharacterized gene positionally cloned by others from chromosome 3p21.3 that is homozygously deleted in several small-cell lung carcinoma cell lines.

Purification and microsequencing of hyaluronidase isozymes from human urine

We recently cloned the major hyaluronidase of human plasma, which we termed HYAL1. All hyaluronidase activity could be purified from human urine on an anti-HYAL1 monoclonal antibody column. However, urine contains two hyaluronidases of 57 kDa and 45 kDa, whereas plasma only contains the 57 kDa activity. Microsequencing confirmed that both urinary isozymes have N-termini identical to plasma hyaluronidase, but a second N-terminus was found in the smaller isozyme, apparently derived from the terminal 25 amino acids of HYAL1, at the C-terminus. The two polypeptides of the 45 kDa isozyme resulting from endoproteolytic cleavage of the 57 kDa isoform are presumably linked by disulfide bonds. Sperm contains two isozymes of the testicular hyaluronidase, PH-20, and the lower molecular weight isozyme is believed to be an endoproteolytically processed form of the larger protein. Analogously to PH-20, the smaller isozyme of HYAL1 is likely to be a proteolytically processed product of the larger isozyme.

Hyaluronan is a prerequisite for ductal branching morphogenesis

Hyaluronan, a macromolecular carbohydrate polymer of the extracellular matrix is prominent early in embryogenesis, coinciding with rapid tissue growth. CD44, the predominant receptor for hyaluronan on vertebrate cells, is a variably expressed transmembrane glycoprotein. Mouse anterior prostate glands obtained at various postnatal time points were examined for the expression of hyaluronan and CD44. Reverse transcriptase polymerase chain reaction analysis was used to map the temporal regulation of specific CD44 variant isoforms. In each age group, hyaluronan was localized exclusively in the stromal matrix. Hyaluronan was greatly reduced in the later ages and was entirely absent around the developmentally quiescent proximal regions of the ducts. Early in prostate development, CD44 was prominent in the mesenchyme. However, in the later phases, CD44 expression became associated with membranes of epithelial cells. The role of hyaluronan-CD44 interactions in ductal branching morphogenesis was studied by serum-free organ culture of mouse anterior prostate. In the presence of optimal levels of testosterone, the organs underwent ductal branching morphogenesis. Treatment with either neutralizing anti-CD44 antibodies, hyaluronan hexasaccharides or the enzyme hyaluronidase inhibited androgen-stimulated ductal branching morphogenesis. These results are suggestive of the significant role played by hyaluronan-CD44 interactions in mediating androgen-induced prostatic growth and morphogenesis.

A microtiter-based assay for hyaluronidase activity not requiring specialized reagents

A sensitive, rapid microtiter-based assay for hyaluronidase activity is described that does not require highly specialized biological reagents, as required heretofore. The free carboxyl groups of hyaluronan are biotinylated in a one-step reaction using biotin-hydrazide. This substrate is then covalently coupled to a 96-well microtiter plate. At the completion of the enzyme reaction, residual substrate is detected with an avidin-peroxidase reaction that can be read in a standard ELISA plate reader. Because the substrate is covalently bound to the microtiter plate, artifacts such as pH-dependent displacement of the biotinylated substrate do not occur. The sensitivity permits rapid measurement of hyaluronidase activity from cultured cells and biological samples with an interassay variation of less than 5%. Using this new assay, we measured the distribution profile of plasma hyaluronidase levels in normal human sera. A 1-microl sample of plasma was sufficient for assays in triplicate. Hyaluronidase activity in human foreskin primary keratinocyte cultures was also quantitated. A 25-fold increase in hyaluronidase activity was observed in keratinocyte cultures induced to differentiate in high calcium (1.5 mM), compared to levels in low calcium (0.05 mM) media. The microtiter-based assay may be used as a routine clinical laboratory procedure.