Abnormal glomerular basement membrane maturation impairs mesangial cell differentiation during murine postnatal nephrogenesis

Although mesangial cell-glomerular basement membrane (GBM) connections play a key role in maintaining the glomerular capillary loop structure, information remains limited about how these connections are formed during glomerulogenesis. We have previously shown that weakened podocyte-GBM interactions owing to tensin 2 (Tns2) deficiency lead to abnormal GBM maturation during postnatal glomerulogenesis. Here, we investigated whether abnormal GBM maturation affected mesangial cell-GBM connections and mesangial cell differentiation. Histological analysis of the outer cortical glomeruli in Tns2-deficient mice revealed that GBM materials overproduced by stressed immature podocytes accumulated in the mesangium and interrupted the formation of mesangial cell-GBM connections, resulting in fewer capillary loops compared with that of normal glomeruli. In addition, expression of α-smooth muscle actin, an immature mesangial cell marker, persisted in mesangial cells of Tns2-deficient outer cortical glomeruli even after glomerulogenesis was completed, resulting in mesangial expansion. Furthermore, analysis of mouse primary mesangial cells revealed that mesangial cell differentiation depended on the type of extracellular matrix components to which the cells adhered, suggesting the participation of mesangial cell-GBM connections in mesangial cell differentiation. These findings suggest that abnormal GBM maturation affects mesangial cell differentiation by impairing mesangial cell-GBM connections.NEW & NOTEWORTHY Mesangial cell-glomerular basement membrane (GBM) connections play an important role in maintaining the structural integrity of the glomerular tuft. However, information remains scarce about how GBM maturation affects the formation of these connections during glomerular development. Here, we show that abnormal GBM maturation due to tensin 2 deficiency affects mesangial cell differentiation by impairing mesangial cell-GBM connections during postnatal glomerulogenesis.

Urinary protein analysis in mice lacking major urinary proteins

Mouse urine contains major urinary proteins (MUPs) that are not found in human urine. Therefore, even healthy mice exhibit proteinuria, unlike healthy humans, making it challenging to use mice as models for human diseases. It was also unknown whether dipsticks for urinalysis could measure protein concentrations precisely in urine containing MUPs. To resolve these problems, we produced MUP-knockout (Mup-KO) mice by removing the Mup gene cluster using Cas9 proteins and two guide RNAs and characterized the urinary proteins in these mice. We measured the urinary protein concentrations in Mup-KO and wild-type mice using a protein quantitation kit and dipsticks. We also examined the urinary protein composition using SDS-PAGE and two-dimensional electrophoresis (2DE). The urinary protein concentration was significantly lower (P<0.001) in Mup-KO mice (17.9 ± 1.8 mg/dl, mean ± SD, n=3) than in wild-type mice (73.7 ± 8.2 mg/dl, n=3). This difference was not reflected in the dipstick values, perhaps due to the low sensitivity to MUPs. This suggests that dipsticks have limited ability to measure changes in MUPs with precision. SDS-PAGE and 2DE confirmed that Mup-KO mice, like humans, had no MUPs in their urine, whereas wild-type mice had abundant MUPs in their urine. The absence of the masking effect of MUPs in 2DE would enable clear comparisons of urinary proteins, especially low-molecular-weight proteins. Thus, Mup-KO mice may provide a useful model for human urinalysis.

Tensin2 is important for podocyte-glomerular basement membrane interaction and integrity of the glomerular filtration barrier

Tensin2 (Tns2), an integrin-linked protein, is enriched in podocytes within the glomerulus. Previous studies have revealed that Tns2-deficient mice exhibit defects of the glomerular basement membrane (GBM) soon after birth in a strain-dependent manner. However, the mechanisms for the onset of defects caused by Tns2 deficiency remains unidentified. Here, we aimed to determine the role of Tns2 using newborn Tns2-deficient mice and murine primary podocytes. Ultrastructural analysis revealed that developing glomeruli during postnatal nephrogenesis exhibited abnormal GBM processing due to ectopic laminin-α₂ accumulation followed by GBM thickening. In addition, analysis of primary podocytes revealed that Tns2 deficiency led to impaired podocyte-GBM interaction and massive expression of laminin-α₂ in podocytes. Our study suggests that weakened podocyte-GBM interaction due to Tns2 deficiency causes increased mechanical stress on podocytes by continuous daily filtration after birth, resulting in stressed podocytes ectopically producing laminin-α₂, which interrupts GBM processing. We conclude that Tns2 plays important roles in the podocyte-GBM interaction and maintenance of the glomerular filtration barrier.

Analysis of the transgene insertion pattern in a transgenic mouse strain using long-read sequencing

Transgene insertion patterns are critical for the analysis of transgenic animals because the influence of transgenes may change depending on the insertion pattern (such as copy numbers and orientations of concatenations) and the insertion position in the genome. We previously reported a genomic walking strategy to locate transgenes in the genomes of transgenic mice (Exp. Anim. 53: 103–111, 2004) and to analyze transgene insertion patterns (Exp. Anim. 55: 65–69, 2006). With such strategies, however, we could not determine the copy number of transgenes or global genome modification induced by transgene insertion due to read-length limitation. In this study, we used a long-read sequencer (MinION, Oxford Nanopore Technologies) to overcome this limitation. We obtained 922,210 reads using MinION with genomic DNA from a transgenic mouse strain (4C30, Proc. Jpn. Acad. Ser. B. Phys. Biol. Sci. 87: 550–562, 2011). Among the reads, we found one 21,457-bp read containing the transgene using a local BLAST search. Nucleotide dot plot analysis revealed that the transgene was inserted in the genome as a tandem concatemer with an almost entire construct (15–3,508 of 3,508 bp) and a partial fragment (4–660, 657 bp). Ensembl’s BLAST search against the C57BL/6N genome revealed a 9,388-bp deletion at the insertion position in the intron of the Sgcd gene, confirming that mutations such as a large genomic deletion could occur at the time of transgene insertion. Thus, long-read sequencers are useful tools for the analysis of transgene insertion patterns.

Essential Role of CARD14 in Murine Experimental Psoriasis

Caspase recruitment domain family member 14 (CARD14) was recently identified as a psoriasis-susceptibility gene, but its immunological role in the pathogenesis of psoriasis in vivo remains unclear. In this study, we examined the role of CARD14 in murine experimental models of psoriasis induced by either imiquimod (IMQ) cream or recombinant IL-23 injection. In all models tested, the psoriasiform skin inflammation was abrogated in Card14-/- mice. Comparison of the early gene signature of the skin between IMQ-cream-treated Card14-/- mice and Tlr7-/-Tlr9-/- mice revealed not only their similarity, but also distinct gene sets targeted by IL-23. Cell type-specific analysis of these mice identified skin Langerinhigh Langerhans cells as a potent producer of IL-23, which was dependent on both TLR7 and TLR9 but independent of CARD14, suggesting that CARD14 is acting downstream of IL-23, not TLR7 or TLR9. Instead, a bone marrow chimera study suggested that CARD14 in radio-sensitive hematopoietic cells was required for IMQ-induced psoriasiform skin inflammation, controlling the number of Vγ4+ T cells producing IL-17 or IL-22 infiltrating through the dermis to the inflamed epidermis. These data indicate that CARD14 is essential and a potential therapeutic target for psoriasis.

Tensin2-deficient mice on FVB/N background develop severe glomerular disease

Tensin2 (Tns2) is an essential component for the maintenance of glomerular basement membrane (GBM) structures. Tns2-deficient mice were previously shown to develop mild glomerular injury on a DBA/2 background, but not on a C57BL/6J or a 129/SvJ background, suggesting that glomerular injury by the deletion of Tns2 was strongly dependent on the genetic background. To further understand the mechanisms for the onset and the progression of glomerular injury by the deletion of Tns2, we generated Tns2-deficient mice on an FVB/N (FVB) strain, which is highly sensitive to glomerular disease. Tns2-deficient mice on FVB (FVBGN) developed severe nephrotic syndrome, and female FVBGN mice died within 8 weeks. Ultrastructural analysis revealed that FVBGN mice exhibited severe glomerular defects with mesangial process invasion of glomerular capillary tufts, lamination and thickening of the GBM and subsequent podocyte foot process effacement soon after birth. Aberrant laminin components containing α1, α2 and β1 chains, which are normally expressed in the mesangium, accumulated in the GBM of FVBGN, suggesting that these components originated from mesangial cells that invaded glomerular capillary tufts. Compared to Tns2-deficient mice on the other backgrounds in previous reports, FVBGN mice developed earlier onset of glomerular defects and rapid progression of renal failure. Thus, this study further extended our understanding of the possible genetic background effect on the deterioration of nephrotic syndrome by Tns2 deficiency.

Zygosity determination in hairless mice by PCR based on Hr(hr) gene analysis

We analyzed the Hr gene of a hairless mouse strain of unknown origin (HR strain, http://animal.nibio.go.jp/e_hr.html) to determine whether the strain shares a mutation with other hairless strains, such as HRS/J and Skh:HR-1, both of which have an Hr^hr allele. Using PCR with multiple pairs of primers designed to amplify multiple overlapping regions covering the entire Hr gene, we found an insertion mutation in intron 6 of mutant Hr genes in HR mice. The DNA sequence flanking the mutation indicated that the mutation in HR mice was the same as that of Hr^hr in the HRS/J strain. Based on the sequence, we developed a genotyping method using PCR to determine zygosities. Three primers were designed: S776 (GGTCTCGCTGGTCCTTGA), S607 (TCTGGAACCAGAGTGACAGACAGCTA), and R850 (TGGGCCACCATGGCCAGATTTAACACA). The S776 and R850 primers detected the Hr^hr allele (275-bp amplicon), and S607 and R850 identified the wild-type Hr allele (244-bp amplicon). Applying PCR using these three primers, we confirmed that it is possible to differentiate among homozygous Hr^hr (longer amplicons only), homozygous wild-type Hr(shorter amplicons only), and heterozygous (both amplicons) in HR and Hos:HR-1 mice. Our genomic analysis indicated that the HR, HRS/J, and Hos:HR-1 strains, and possibly Skh:HR-1 (an ancestor of Hos:HR-1) strain share the same Hr^hr gene mutation. Our genotyping method will facilitate further research using hairless mice, and especially immature mice, because pups can be genotyped before their phenotype (hair coat loss) appears at about 2 weeks of age.

Tenc1-deficient mice develop glomerular disease in a strain-specific manner

BACKGROUND/AIMS

Tenc1 (also known as tensin2) is an integrin-associated focal adhesion molecule that is broadly expressed in mouse tissues including the liver, muscle, heart and kidney. A mouse strain carrying mutated Tenc1, the ICR-derived glomerulonephritis (ICGN) strain, develops severe nephrotic syndrome.

METHODS

To elucidate the function of Tenc1 in the kidney, Tenc1(ICGN) was introduced into 2 genetic backgrounds, i.e. DBA/2J (D2) and C57BL/6J (B6), strains that are respectively susceptible and resistant to chronic kidney disease.

RESULTS

Biochemical and histological analysis revealed that homozygous Tenc1(ICGN) mice develop nephrotic syndrome on the D2 background (D2GN) but not on the B6 background (B6GN). Initially, abnormal assembly and maturation of glomerular basement membrane (GBM) were observed, and subsequently effacement of podocyte foot processes was noted in the kidneys of D2GN but not B6GN mice. These defects are likely to be involved in the integrin signaling pathway.

CONCLUSION

This study suggests that Tenc1 contributes to the maintenance of GBM structures and that the genetic background influences the severity of nephrotic syndrome.

Gene expression analysis detected a low expression level of C1s gene in ICR-derived glomerulonephritis (ICGN) mice

BACKGROUND

ICR-derived glomerulonephritis (ICGN) strain is a novel inbred strain of mice with a hereditary nephrotic syndrome. Deletion mutation of tensin 2 (Tns2), a focal adhesion molecule, has been suggested to be responsible for nephrotic syndrome in ICGN mice; however, the existence of other associative factors has been suggested.

METHODS AND RESULTS

To identify additional associative factors and to better understand the onset mechanism of nephrotic syndrome in ICGN mice, we conducted a comprehensive gene expression analysis using DNA microarray. Immune-related pathways were markedly altered in ICGN mice kidney as compared with ICR mice. Furthermore, the gene expression level of complement component 1, s subcomponent (C1s), whose human homologue has been reported to associate with lupus nephritis, was markedly low in ICGN mouse kidney. Real-time quantitative reverse transcription-polymerase chain reaction confirmed a low expression level of C1s in ICGN mouse liver where the C1s protein is mainly synthesized. A high serum level of anti-dsDNA antibody and deposits of immune complexes were also detected in ICGN mice by enzyme-linked immunosorbent assay and immunohistochemical analyses, respectively.

CONCLUSION

Our results suggest that the immune system, especially the complement system, is associated with nephrotic syndrome in ICGN mice. We identified a low expression level of C1s gene as an additional associative factor for nephrotic syndrome in ICGN mice. Further studies are needed to elucidate the role of the complement system in the onset of nephrotic syndrome in ICGN mice.

Oral glucose loading modulates plasma β-amyloid level in alzheimer's disease patients: potential diagnostic method for Alzheimer's disease

BACKGROUND

Although plasma β-amyloid (Aβ) has been suggested to be a noninvasive diagnostic biomarker for Alzheimer's disease (AD), its significance and validity have been inconclusive. Thus, it is quite important to establish a novel diagnostic method related to plasma Aβ.

METHODS

As our previous animal studies demonstrated a relation of glucose with plasma Aβ, we examined the effect of glucose loading on plasma Aβ levels in AD patients. After fasting, an oral glucose load was administered to AD patients and non-AD dementia patients, and subsequently, blood glucose, plasma insulin, and plasma Aβ levels were measured.

RESULTS

The plasma levels of baseline blood glucose, plasma insulin, and plasma Aβ were not different between the two groups. However, immediately after glucose loading, a significant increase in plasma Aβ40 and Aβ42 levels was observed in AD patients, whereas a mild decrease in plasma Aβ40 and Aβ42 levels was detected in non-AD dementia patients.

CONCLUSION

The present study clearly demonstrated a different response in plasma Aβ40 and Aβ42 levels after glucose loading between AD and non-AD dementia patients, which is consistent with our previous animal studies. These findings suggest a novel diagnostic tool for AD using the elevation of plasma Aβ level after glucose loading, although further studies are necessary.

319 REDUCED SUPEROVULATION EFFICIENCY BY HIGH-DOSE TREATMENT OF DEHYDROEPIANDROSTERONE IN MICE

Strain differences in in vitro fertilizability still constitute a serious problem in mouse reproduction. To improve the in vitro fertilizability of mouse oocytes, we examined the effect of implanting time-release pellets of dehydroepiandrosterone (DHEA), a testosterone precursor, in female mice on oocyte fertilizability. The DHEA pellets (0.25, 1.5, or 5 mg pellet–1, 21-day release form, Innovative Research of America, Sarasota, FL, USA) or corresponding placebo pellets were implanted subcutaneously in 9-week-old female 129X1/SvJJmsSlc mice. On Day 18 of implantation, superovulation was induced in these females by injections of pregnant mare serum gonadotropin (PMSG) and hCG 48 h apart. On Day 21, IVF was conducted using oocytes collected from the oviducal ampullae of these females and epididymal sperm from Slc : ICR male mice using TYH medium. Then, the embryos were cultured in vitro in Whitten’s medium for 96 h. Plasma steroid levels and expression of 5 ovarian proteins (PTEN and receptors for FSH, androgen, oestrogen, and progesterone) at oocyte collection were measured by enzyme immunoassay and quantitative Western blots, respectively. Embryo development into 2-cell and blastocyst stages at each dose at 24 h and 96 h after insemination, respectively, were compared between DHEA and placebo groups using weighted ANOVA with angular transformations. Other observed values were compared using Student’s t-test. Treatment with DHEA suppressed the numbers of ovulated oocytes in the 1.5 and 5 mg groups (DHEA v. placebo: 21.0 ± 2.6 v. 32.5 ± 2.8 and 19.9 ± 1.4 v. 27.1 ± 1.6, respectively, n = 10; P < 0.05), but not in the 0.25 mg group (26.6 ± 3.2 v. 24.8 ± 2.4). Treatment with DHEA did not affect the percentages of 2-cell embryo formation at any dose, ranging 50 to 60%. In the 0.25 mg group, DHEA treatment tended to increase blastocyst formation rate (1.8 ± 0.8% v. 0.4 ± 0.4%; not significant). However, the treatment at 1.5 mg suppressed the rate (0.0 ± 0.0% v. 3.1 ± 0.7%; P < 0.05) and treatment at 5 mg did not affect the rate (1.3 ± 0.9% v. 0.8 ± 0.6%). Plasma testosterone levels were increased by DHEA at 1.5 and 5 mg (338.2 ± 39.8 v. 197.0 ± 8.9 pg mL–1 and 534.9 ± 111.4 v. 241.8 ± 34.4 pg mL–1, respectively, n = 6; P < 0.05), but not at 0.25 mg (247.4 ± 22.0 v. 252.5 ± 35.6 pg mL–1, n = 6). No significant difference was induced by DHEA in plasma DHEA, progesterone, or oestradiol at any doses. Ovarian PTEN protein was more abundant in DHEA group than in placebo group at 5 mg (P < 0.05), tended to be more abundant at 1.5 mg (P ≈ 0.14), and was not different at 0.25 mg (P ≈ 0.35). The amounts of the 4 receptor proteins were not significantly changed by DHEA at any dose. These results suggest that DHEA at a low dose (e.g. 0.25 mg pellets for 21 days) might have a potential to improve in vitro fertilizability of mouse oocytes. Higher doses of DHEA reduced superovulation efficiency, perhaps because of the high testosterone level induced by the high-dose treatment of DHEA. The high testosterone level might upregulate ovarian PTEN expression, which might suppress ovarian primordial follicle activation. A more detailed study is needed to determine the optimal dose, timing, and duration of DHEA treatment for the improvement of female fertilizability.

179 EFFECTS OF DEHYDROEPIANDROSTERONE ON SPERM FERTILIZABILITY IN VITRO AND TESTICULAR GENE EXPRESSION

Strain differences of in vitro fertilizability still constitute a serious problem in mouse reproduction. To improve the in vitro fertilizability of mouse sperm, we examined the effects of implanting time-release pellets of dehydroepiandrosterone (DHEA), a testosterone precursor, on sperm fertilizability and testicular gene expression. DHEA pellets (5 mg pellet–1, 21-day release form; Innovative Research of America) or placebo pellets were implanted subcutaneously in 9-week-old male mice from 2 strains: C57BL/6CrNSlc (B6) and 129X1/SvJJmsSlc (129X1). After 21 days, in vitro fertilization was conducted using epididymal sperm from these males and oocytes from superovulated 4-week-old Slc:ICR females. The percentages of 2-cell embryo formation in the placebo and DHEA groups were 78.2 ± 14.2% vs 89.3 ± 2.5%, respectively (mean ± standard error of the mean, n = 4 per group) using B6 sperm and 40.9 ± 8.8% vs 41.3 ± 3.1%, respectively (n = 4 per group) using 129X1 sperm, indicating no significant effect of DHEA treatment (P > 0.05 by 2-way ANOVA). However, a strain difference was quite evident (P < 0.05 by 2-way ANOVA). Quantitative Western blotting using testicular protein extracts with glyceraldehyde-3-phosphate dehydrogenase as an internal control showed that the expression of androgen receptor protein (AR) was significantly higher in B6 than in 129X1 males (P < 0.05 by 2-way ANOVA), whereas there was no significant effect of DHEA on the amount of AR in either strain (P > 0.05 by 2-way ANOVA). In B6 testes, 2-dimensional electrophoresis indicated that 1 protein spot was denser in DHEA-treated males than in placebo-treated males. In 129X1 testes, DHEA did not change the density of the corresponding spot. Mass spectrometry of the spot suggested that it was Cu/Zn superoxide dismutase (SOD1). Thus, 21-day-release pellets of 5 mg DHEA had no significant effect on sperm fertilizability in vitro in 2 strains, but the DHEA pellets induced a strain-dependent testicular protein expression, which might be because of the differential AR expression. Although DHEA treatment of male mice has the potential to improve sperm fertilizability in vitro, a more detailed study is needed to determine the optimal dose, age and duration of DHEA treatment. This work was supported by a grant from the Ministry of Health, Labour and Welfare, Japan.

Role of insulin signaling in the interaction between Alzheimer disease and diabetes mellitus: a missing link to therapeutic potential

Diabetes mellitus (DM) is one of the major non-genetic risk factors for Alzheimer disease (AD). However, the mechanism by which DM increases the risk of AD has not been elucidated. Here, we summarize recent findings to address this question. Whereas neuropathological studies in humans suggest that DM does not increase Aβ accumulation in the brain (a major hallmark of AD), earlier works in animal models show that Aβ does accumulate. Therefore, alternate mechanisms might exist. Recent studies using the human brain indicate that insulin signaling is impaired in the AD brain. In neurons, this insulin signaling plays a key role in modulating synaptic function and neuronal senescence besides regulating tau phosphorylation, another hallmark of AD. On the other hand, in cerebrovessels, DM causes vascular remodeling, which involves increased RAGE (receptor for advanced glycation endproducts) expression, and AD is associated with cerebrovascular amyloid angiopathy (CAA). Our recent study involving AD mice with DM has revealed that a vicious circle underlies the interaction between AD and DM. Interestingly, in our mouse model, AD increased RAGE expression, and DM worsened CAA. The contribution of vascular factors such as RAGE expression and CAA to the impairment of insulin signaling will be discussed. This impaired insulin signaling might be a possible link between AD and DM. Moreover, insulin signaling is also involved in the mechanism of aging, decreasing with an increase in age. An identification of the mechanism whereby DM modifies the pathological condition of AD through the modulation of insulin signaling is required to develop potential therapeutics for AD not only with but also without DM.

Adult onset cardiac dilatation in a transgenic mouse line with Galβ1,3GalNAc α2,3-sialyltransferase II (ST3Gal-II) transgenes: a new model for dilated cardiomyopathy

Sugar chain abnormalities in glycolipids and glycoproteins are associated with various diseases. Here, we report an adult onset cardiac dilatation in a transgenic mouse line with Galβ1,3GalNAc α2,3-sialyltransferase II (ST3Gal-II) transgenes. The transgenic hearts at the end-stage, at around 7 months old, were enlarged, with enlarged cavities and thin, low-tensile walls, typical of dilated cardiomyopathy. Although no apparent change was found in heart gangliosides, glycosylation of heart proteins was altered. Interestingly, sugar moieties not directly related to the ST3Gal-II catalytic reaction were also changed. Significant increases in calreticulin and calnexin were observed in hearts of the transgenic mice. These results suggest that expression of ST3Gal-II transgenes induces abnormal protein glycosylation, which disorganizes the endoplasmic/sarcoplasmic reticulum quality control system and elevates the calreticulin/calnexin level, resulting in suppression of cardiac function. The transgenic mice showed 100% incidence of adult onset cardiac dilatation, suggesting great potential as a new model for dilated cardiomyopathy.

94 EFFECT OF OVARIAN SIZE ON THE VIABILITY OF CRYOPRESERVED SYRIAN HAMSTER OVARIES

Ovaries can be used in place of gametes as a resource for cryopreservation. Thus far, we have shown that in the Syrian hamster, pups can be successfully produced through the transplantation of fresh and cryopreserved ovaries. In this study, we attempted to simplify the ovarian cryopreservation procedures to facilitate the easy application of these techniques. In particular, the procedure would be easier and quicker if the ovaries did not have to be cut into small pieces before ovarian cryopreservation. Therefore, we examined the effects of ovarian fragment size on subsequent offspring production. Ovaries were cryopreserved by vitrification according to methods described for mouse ovaries (Migishima et al. 2003 Biol. Reprod. 68, 881–887). In brief, ovaries were collected from 3-week-old J2N-n strain (white coat) females. Because we had previously confirmed that quarter-sized ovaries could be used for cryopreservation, intact (∼3.5 × 2 mm) and half-sliced ovaries (∼2 × 1.5 mm) were cryopreserved by vitrification using DAP213 solution (2 M dimethyl sulfoxide, 1 M acetamide, and 3 M propylene glycol; Nakagata 1989 J. Reprod. Fertil. 87, 479–483). Thawed ovaries were transferred into the ovarian bursae (single intact ovary or two half-sliced ovarian pieces per ovarian bursa) of 3-week-old recipient females with agouti-coat (Slc:Syrian) under isoflurane anaesthesia. Not all of the recipients’ ovaries were removed immediately before transfer; both the donor’s and a small portion of the recipient’s ovaries were present in each ovarian bursa. Successful ovarian transplantation was verified by examining the coat colour (non-agouti colour) of offspring produced in test matings between mature recipients and J2N-n males. Of the 3 and 6 recipients that received intact and sliced ovaries, respectively, 2 and 5 recipients delivered pups. Based on the coat colour of the pups, 1 of the 5 recipients delivered a pup produced from transplanted half-sliced ovaries. Our results indicate that half-sliced-size ovaries (smaller than a 2-mm cube) can be successfully used for cryopreservation in the Syrian hamster. Specifically, it is not required to slice the ovary into smaller pieces. This work was supported by a grant from the Ministry of Health, Labour and Welfare, Japan and Grant-in-Aid for Scientific Research (C).

Increased globotriaosylceramide levels in a transgenic mouse expressing human alpha1,4-galactosyltransferase and a mouse model for treating Fabry disease

Fabry disease is a lysosomal storage disorder caused by an α-galactosidase A (α-Gal A) deficiency and resulting in the accumulation of glycosphingolipids, predominantly globotriaosylceramide (Gb3). A transgenic mouse expressing the human α-Gal A R301Q mutant in an α-Gal A-knockout background (TgM/KO) should be useful for studying active-site-specific chaperone (ASSC) therapy for Fabry disease. However, the Gb3 content in the heart tissue of this mouse was too low to detect an ASSC-induced effect. To increase the Gb3 levels in mouse organs, we created transgenic mice (TgG3S) expressing human α1,4-galactosyltransferase (Gb3 synthase). High levels of Gb3 were observed in all major organs of the TgG3S mouse. A TgG3S (+/-)M(+/-)/KO mouse was prepared by cross-breeding the TgG3S and TgM/KO mice and the Gb3 content in the heart of the TgG3S(+/-)M(+/-)/KO mouse was 1.4 µg/mg protein, higher than in the TgM(+/-)/KO (<0.1 µg/mg protein). Treatment with an ASSC, 1-deoxygalactonojirimycin, caused a marked induction of α-Gal A activity and a concomitant reduction of the Gb3 content in the TgG3S(+/-) M(+/-)/KO mouse organs. These data indicated that the TgG3S(+/-) M(+/-)/KO mouse was suitable for studying ASSC therapy for Fabry disease, and that the TgG3S mouse would be useful for studying the effect of high Gb3 levels in mouse organs.

Activating transcription factor 3 constitutes a negative feedback mechanism that attenuates saturated Fatty acid/toll-like receptor 4 signaling and macrophage activation in obese adipose tissue

Obese adipose tissue is markedly infiltrated by macrophages, suggesting that they may participate in the inflammatory pathways that are activated in obese adipose tissue. Evidence has suggested that saturated fatty acids released via adipocyte lipolysis serve as a naturally occurring ligand that stimulates Toll-like receptor (TLR)4 signaling, thereby inducing the inflammatory responses in macrophages in obese adipose tissue. Through a combination of cDNA microarray analyses of saturated fatty acid-stimulated macrophages in vitro and obese adipose tissue in vivo, here we identified activating transcription factor (ATF)3, a member of the ATF/cAMP response element-binding protein family of basic leucine zipper-type transcription factors, as a target gene of saturated fatty acids/TLR4 signaling in macrophages in obese adipose tissue. Importantly, ATF3, when induced by saturated fatty acids, can transcriptionally repress tumor necrosis factor-alpha production in macrophages in vitro. Chromatin immunoprecipitation assay revealed that ATF3 is recruited to the region containing the activator protein-1 site of the endogenous tumor necrosis factor-alpha promoter. Furthermore, transgenic overexpression of ATF3 specifically in macrophages results in the marked attenuation of proinflammatory M1 macrophage activation in the adipose tissue from genetically obese KKA(y) mice fed high-fat diet. This study provides evidence that ATF3, which is induced in obese adipose tissue, acts as a transcriptional repressor of saturated fatty acids/TLR4 signaling, thereby revealing the negative feedback mechanism that attenuates obesity-induced macrophage activation. Our data also suggest that activation of ATF3 in macrophages offers a novel therapeutic strategy to prevent or treat obesity-induced adipose tissue inflammation.

Elevation of plasma beta-amyloid level by glucose loading in Alzheimer mouse models

With the emergence of a promising approach to treat Alzheimer disease (AD) targeting the beta-amyloid (Abeta) pathway, it is necessary to establish new diagnostic biomarkers that enable the antemortem diagnosis of AD. Although plasma Abeta has been suggested as a non-invasive biomarker, its significance has been inconclusive. Thus, it is important to improve the diagnostic potential of plasma Abeta. One of the potential approaches is to modify plasma Abeta level using various modulators. In this study, we evaluated the influence of glucometabolic status on plasma Abeta level in two lines of AD transgenic mouse. The present study demonstrated that plasma Abeta level rapidly increased after glucose loading. More importantly, the magnitude of the increase in plasma Abeta was significantly larger in AD transgenic mice than in wild-type littermates. These findings might provide a novel diagnostic tool for AD using the elevation of plasma Abeta level after glucose loading.

77 SUCCESSFUL CRYOPRESERVATION OF SYRIAN HAMSTER OVARIES BY VITRIFICATION

In place of gametes, ovaries can be used as an alternative resource for cryopreservation. At the previous IETS meeting, we showed that in the Syrian hamster, pups could be successfully produced through the transplantation of fresh ovaries. In addition, the immunotolerance of interstrain ovarian transplantation was described. In this study, we attempted to produce pups via transplantation of cryopreserved ovaries to foster mothers. Our goal was to establish a preservation method for hamster strains based on ovarian cryopreservation in combination with ovarian transfer. Ovaries were cryopreserved by vitrification according to methods described for mouse ovaries (Migishima F et al. 2003 Biol. Reprod. 68, 881–887). In brief, ovaries were collected from 2- to 3-week-old HAW strain (white coat) females. Each ovary was cut into 4 sections, placed into 1 tube, and cryopreserved by vitrification using DAP213 solution (2 m dimethyl sulfoxide, 1 m acetamide, and 3 m propylene glycol; Nakagata N 1989 J. Reprod. Fertil. 87, 479–483). Thawed ovaries were transferred into the ovarian bursae (2 ovarian sections per ovarian bursa) of 3-week-old recipient females with agouti coat (Slc:Syrian) under anesthesia with isoflurane. Half of the recipients’ ovaries were removed immediately before transfer; i.e. both donor and recipient ovaries were present in each ovarian bursa. Successful ovarian transplantation was verified by examining the coat color (non-agouti color) of offspring produced in test matings between mature recipients and Slc:Syrian males. Out of 6 recipients tested, 2 became pregnant and delivered pups. According to the coat color of the pups, 1 of the 2 recipients delivered a pup produced from transplanted ovaries (1 out of 4 pups). Regardless of this low success rate, our results indicate that pups can be produced from cryopreserved ovaries via interstrain transplantation of ovaries to foster mothers in the Syrian hamster. Thus, ovarian cryopreservation by vitrification is a promising strategy for strain preservation of the Syrian hamster. This work was supported by a grant from the Ministry of Health, Labor, and Welfare, Japan.

Type 2 diabetes mellitus in a non-obese mouse model induced by Meg1/Grb10 overexpression

We assessed the possibility of C57BL/6-Tg (Meg1/Grb10)isn(Meg1 Tg) mice as a non-obese type 2 diabetes (2DM) animal model. Meg1 Tg mice were born normal, but their weight did not increase as much as normal after weaning and showed about 85% of normal size at 20 weeks of age. Body mass index of Meg1 Tg mice was also smaller than that of control mice. The glucose tolerance test and insulin tolerance test showed that Meg1 Tg mice had reduced ability to normalize the blood glucose level. Blood urea nitrogen (BUN) in Meg1 Tg mice (19.6 +/- 1.2 mg/dl) was significantly lower than in controls (22.0 +/- 0.8 mg/dl), while plasma triglyceride, insulin, adiponectin, and resistin levels were significantly higher (202.0 +/- 23.4 mg/dl vs 146.3 +/- 23.4 mg/dl, 152.4 +/- 16.3 pg/ml vs 88.1 +/- 16.9 pg/ml, 74.4 +/- 10.9 microg/ml vs 48.3 +/- 7.0 microg/ml, and 4.0 +/- 0.2 ng/ml vs 3.6 +/- 0.2 ng/ml, respectively). Body, visceral fat weight and liver weights were significantly lower (19.6 +/- 0.4 g vs 24.3 +/- 0.3 g, 376.7 +/- 29.6 mg to 507.5 +/- 23.0 mg, and 906.0 +/- 41.8 mg to 1,001.0 +/- 15.1 mg, respectively). Thus, hyperinsulinemia observed in Meg1 Tg mice indicates that their insulin signaling pathway is somehow inhibited. With high fat diet, the diabetes onset rate of Meg1 Tg mice increased up to 60%. These results suggest that Meg1 Tg mice resemble human 2DM.

148 PRODUCTION OF PUPS BY OVARIAN TRANSFER IN THE SYRIAN HAMSTER

Instead of gametes, ovaries could be used as alternative resources for cryopreservation. In this study, we attempted to produce pups by transplantation of fresh ovaries to foster mothers as a first step to establish a preservation method of hamster strains on the basis of the cryopreservation of ovaries in combination with ovarian transfers. We also checked the possibility of inter-strain transfers of ovaries, since immunological tolerance among hamster strains is suggested by the fact that most Syrian hamsters were derived from only a small number of animals. Fresh ovaries collected from 3-weekold females of HAW (white coat) and APA (albino) strains were transferred into ovarian bursae of 3-week-old recipient females with agouti-coat (Slc:Syrian) under anesthesia with xylazine and ketamine. Halves of ovaries of recipients were removed immediately before the transfers, i.e., both donor and recipient ovaries were present in each ovarian bursa. Successful transplantation of ovaries was checked by the coat color (non-agouti color) of offspring produced by test matings of recipients with Slc:Syrian males after the recipients became mature. Five and six recipients received HAW and APA ovaries, respectively. All 11 recipients tested became pregnant and delivered pups. According to the coat color of the pups, three of five recipients which received HAW ovaries and one of six recipients which received APA ovaries delivered pups derived from transplanted ovaries (two out of eight pups, one out of seven pups, and three out of 11 pups for HAW; one out of five pups for APA). Our results indicate that transplantation of fresh ovaries to foster mothers could be used for production of pups from grafted ovaries in the Syrian hamster. In particular, immunological tolerance for ovarian transfers among at least three strains suggests that recipient strains might not need to be the same as donor strains for practical ovarian transfers in the Syrian hamster. Our results would facilitate the development of a strain preservation system for the Syrian hamster based on ovarian cryopreservation. This work was supported by a grant from the Ministry of Health, Labor, and Welfare of Japan.

Analyses of the cDNA and genomic DNA sequences encoding the luteinizing hormone beta-subunit precursor protein in the rabbit

To examine the molecular basis for efficient induction of superovulation in the rabbit, we determined the cDNA sequences of the luteinizing hormone beta-subunit (LHB) from Japanese White (JW), New Zealand White (NZW), and Dutch-Belted (Dutch) rabbits, and we compared these LHB sequences with those of other mammals. Using 5'- and 3'-rapid amplification of cDNA ends (RACE) with pituitary cDNA libraries, we found that the LHB cDNAs of all three breeds are the same length (523 bp from the 5'-end to the polyA site) and have putative AATAAA polyadenylation signal sequences at nucleotides 504 to 509. Northern blot analysis indicated that the approximately 600-nt mRNA encoding JW LHB is slightly longer than the LHB mRNAs of the other two breeds. The NZW and Dutch rabbit LHB coding sequences are 426 bp long, and their G+C contents are higher (>73%) than those of other mammalian LHBs (<70%). The predicted 141-amino-acid sequences of the JW and NZW LHB proteins are identical, and the Dutch LHB and JW/NZW sequences differ at only two residues. The exon-intron configuration of the NZW LHB gene (three exons and two introns) is similar to that of other mammalian LHB genes, and the sequences of NZW rabbit and other mammalian LHB promoter regions are highly conserved. Phylogenetic analysis of the deduced amino acid sequences of the three rabbit LHB proteins indicated that the rabbit occupies a phylogenetic position between rodents and domestic animals, and is far from humans. The results suggest that LH prepared from rodents or domestic animals, if available, would be a better inducer for superovulation in rabbits than human LH/CG.

Deficiency of the tensin2 gene in the ICGN mouse: an animal model for congenital nephrotic syndrome

The ICGN mouse is a model for nephrotic syndrome (NS) which presents with proteinuria, hyperlipidemia, and edema. In this study we attempted to identify the gene(s) responsible for NS. By analyzing albuminuria in 160 (ICGN x MSM)F(1) x ICGN backcross progenies, we found that NS in the ICGN mouse is caused by more than one gene. We then performed a quantitative trait locus (QTL) analysis and detected a QTL with a very high LOD score peak in the telomeric region of Chr 15. By analyzing the nucleotide sequence of 22 genes located close to the QTL, we found that the tensin2 gene of the ICGN mouse possessed an 8-nucleotide deletion mutation in exon 18, leading to a frameshift and giving rise to a terminal codon at a premature position. Analyses of in situ hybridization and immunohistochemistry revealed that tensin2 was expressed in podocytes and tubular epithelial cells in normal mice but not in the ICGN mouse. These data raise the possibility that a mutation of the tensin2 gene is responsible for NS of the ICGN mouse and tensin2 is a prerequisite for the normal kidney function.

Sequence analysis of cDNA encoding rabbit follicle-stimulating hormone beta-subunit precursor protein

To understand the molecular basis of the rabbit's efficient superovulation, we determined the cDNA sequence of the follicle-stimulating hormone (FSH) beta-subunit precursor protein using a combination of 5'- and 3'-rapid amplification of cDNA ends (RACE) with pituitary cDNA libraries of the Japanese White rabbit and compared it with those of other mammals. RACE experiments detected at least three transcripts for the FSHbeta precursor protein in the libraries. The transcripts had lengths of 457, 1,621, and 1,767 bp, from the 5'-end to the poly(A) site. The shortest and mid-length transcripts had the putative polyadenylation signal sequence AATAAA at nucleotides 436 and 1,601, respectively, whereas the longest form had an ATTAAA sequence at nucleotide 1,745 of the cDNA sequence. These transcripts are likely to be polyadenylation variants of one large transcript because they share the same coding sequence for the precursor protein (130 amino acid residues in length). However, only a few shortest variants seem to be formed because the shortest variants were not detected by Northern blot analysis. Phylogenetic analysis of the deduced amino acid sequence indicates that the rabbit is phylogenetically closer to humans than to the other mammals, suggesting that an FSH preparation from human sources would be superior as a follicle stimulant for the induction of superovulation.

Transgene insertion pattern analysis using genomic walking in a transgenic mouse line

A transgene mapping technique (Noguchi et al., Exp. Anim. 53:103-111, 2004) is described that can be used to analyze transgene integration patterns in transgenic mice. The technique was used to reveal that a transgenic mouse line (GM1-sy#116) harbored inverted and direct tandem repeats of both intact and partial pCAGGS-based transgenes in the G2 region of chromosome 1. This complicated concatenation of transgenes may have been caused by simple end-joining of DNA constructs fragmented by exposure to UV transillumination during gel-purification, and by nuclease digestion inside zygote pronuclei. The results suggest that care should be taken to avoid unwanted fragmentation during the preparation of vector constructs.

Transforming growth factor-β1 mediated up-regulation of lysyl oxidase in the kidneys of hereditary nephrotic mouse with chronic renal fibrosis

Lysyl oxidase (LOX), an extracellular enzyme, plays a key role in the post-translational modification of collagens and elastin, catalyzing inter- and intra-crosslinking reactions. Because the crosslinked extracellular matrices (ECMs) are highly resistant to degradative enzymes, it is considered that the over-expression of LOX may cause severe fibrotic degeneration. In the present study, we addressed the role of LOX-mediated crosslinking in chronic renal tubulointerstitial fibrosis using an animal model of hereditary nephrotic syndrome, the Institute of Cancer Research (ICR)-derived glomerulonephritis (ICGN) mouse. Ribonuclease protection assay (RPA) revealed that LOX mRNA expression was up-regulated in the kidneys of ICGN mice as compared with control ICR mice. High-level expression of LOX and transforming growth factor (TGF)-beta1 (an up-regulator of LOX) mRNA was detected in tubular epithelial cells of ICGN mouse kidneys by in situ hybridization. Type-I and -III collagens, major substrates for LOX, were accumulated in tubulointerstitium of ICGN mouse kidneys. The present findings imply that TGF-beta1 up-regulates the production of LOX in tubular epithelial cells of ICGN mouse kidneys, and the excessive LOX acts on interstitial collagens and catalyzes crosslinking reactions. As a result, the highly crosslinked collagens induce an irreversible progression of chronic renal tubulointerstitial fibrosis in the kidneys of ICGN mice.

Effect of human erythropoietin (hEPO) treatment on anemia in ICR-derived glomerulonephritis (ICGN) mice

ICR-derived glomerulonephritis (ICGN) mice are a novel inbred strain with hereditary nephrotic syndrome and are thus considered a good animal model of human idiopathic nephrotic syndrome. In the present study, we investigated the effect to erythrocyte production by human erythropoietin (hEPO) treatment in ICGN mice during the early nephrotic stage. Erythrocyte count, hemoglobin concentration and hematocrit value in hEPO-treated (5 U/body/day, for 5 days) ICGN mice were recovered to the levels found in normal ICR mice. In addition, there was no correlation between plasma creatinine level, a marker of renal function, and erythrocyte count after hEPO treatment. Therefore, anemia in ICGN mice may be caused by decreased production of EPO in the kidney following progressive parenchymal damage.

Decreased expression of matrix metalloproteinases and tissue inhibitors of metalloproteinase in the kidneys of hereditary nephrotic (ICGN) mice

Matrix metalloporoteinases (MMPs), which are dominantly regulated by tissue inhibitors of metalloproteinase (TIMPs), play important roles in extracellular matrix (ECM) degradation and are involved in the progression of kidney diseases. In glomeruli and tubulointerstitum of hereditary nephrotic (ICR-derived glomerulonephritis: ICGN) mouse kidneys, hyper-accumulation of ECM components occurred, and MMP activity decreased. In the present study, because lower levels of MMP activity may contribute to the progression of renal fibrosis in ICGN mice, Western blotting analysis and immunohistochemical staining for MMPs and TIMPs were performed to verify the expression levels of these proteins. Levels of MMP-2, MMP-9, MT1-MMP, TIMP-1 and TIMP-2 in the kidneys were decreased in ICGN mice in comparison with normal ICR mice. These results indicate that small amounts and low levels of activity of MMPs cause the progression of renal fibrosis in ICGN mice.

Sequence analysis of cDNA encoding follicle-stimulating hormone and luteinizing hormone beta-subunits in the Mastomys (Praomys coucha)

To examine the molecular basis of efficient superovulation in the Mastomys (Praomys coucha), the cDNA sequences of the follicle-stimulating hormone (FSH) and luteinizing hormone (LH) beta-subunits were determined and compared with those of other mammals. FSHbeta and LHbeta cDNAs were 1606 and 513 bp long, respectively, from the 5'-ends to the putative polyA sites. The deduced sequences of the FSHbeta and LHbeta precursor proteins were 130 and 141 amino acids in length, respectively. The amino acid sequences of both mastomys hormone subunits showed overall similarity to those of other rodents. In particular, the N-terminus of the FSHbeta precursor protein is of the MM-type, like those of mice and rats, which suggests that the MM-type is characteristic of the subfamily Murinae. As we reported earlier for the Mongolian gerbil, the use of hCG for superovulation of mastomys might need to be re-evaluated, due to the low homology between hCG and rodent LH sequences.

Augmented cytoplasmic Smad4 induces acceleration of TGF-?1 signaling in renal tubulointerstitial cells of hereditary nephrotic ICGN mice with chronic renal fibrosis; possible role for myofibroblastic differentiation

The Institute of Cancer Research (ICR)-derived glomerulonephritis (ICGN) mouse is a hereditary model animal for nephrotic syndrome with chronic renal tubulointerstitial fibrosis. In most fibrotic diseases, myofibroblastic differentiation is considered to play crucial roles in pathogenesis of fibrosis and is dominantly regulated by the transforming growth factor (TGF)-beta1 signaling system. To reveal the pathogenic mechanism of chronic renal fibrosis in ICGN mice, we examined the expression and localization of TGF-beta1 signal transducer proteins (TGF-beta receptor-I and -II, Smad2/3 and Smad4) in kidney sections and in primarily cultured tubulointerstitial fibroblasts (TIFs). In kidneys of ICGN mice, many tubulointerstitial cells were differentiated to myofibroblastic cells and were alpha-smooth muscle actin (alphaSMA)-positive. The numbers of alphaSMA-positive TIFs prepared from kidneys of ICGN mice (ICGN-TIFs), but not those of ICR control mice (ICR-TIFs), increased during cell culture. No significant differences in production or activation of TGF-beta1 between ICGN-TIFs and ICR-TIFs were seen by enzyme-linked immunosorbent assay. In vitro transcriptional reporter assay for TGF-beta1 and Western immunoblotting for TGF-beta1 signal transducers showed no notable differences in the expression levels of TGF-beta receptor-I or -II or Smad2/3 between these TIFs. However, augmented cytoplasmic Smad4 protein in ICGN-TIFs, but not ICR-TIFs, seemed to cause hypersensitivity against TGF-beta1, and the eventual nuclear localization of Smad2/3-Smad4 complex was increased in ICGN-TIFs. Thus, the abnormal cytoplasmic augmentation of Smad4 induces acceleration of TGF-beta1 signaling in the renal tubulointerstitial cells of ICGN mice.

Anemia with Chronic Renal Disorder and Disrupted Metabolism of Erythropoietin in ICR-derived Glomerulonephritis (ICGN) Mice

The ICR-derived glomerulonephritis (ICGN) mouse, a new inbred mouse strain with a hereditary nephrotic syndrome, is considered to be a good model of human idiopathic nephrotic syndrome and notably exhibits proteinuria and hypoproteinemia from the neonatal stage. In chronic renal disorder (CRD), anemia is a major subsequent symptom (renal anemia). The precise cause of renal anemia remains unclear, primarily owing to the lack of appropriate spontaneous animal models for CRD. To establish adequate animal models for anemia with CRD, we examined the hematological-biochemical properties and histopathological characteristics. With the deterioration of renal function, ICGN mice developed a normochromic and normocytic anemia, and exhibited normochromic and microcytic at the terminal stage. The expression of erythropoietin (EPO) mRNA both in the kidneys and liver and the EPO leak into the urine were observed in ICGN mice, indicating a disrupted metabolism of EPO in ICGN mice. In addition, a lack of iron induced by the hemolysis in the spleen and the leak of transferrin into urine as proteinuria aggravated the anemic condition. In conclusion, the ICGN mouse is a good model for anemia with CRD.

Localization of extracellular matrix receptors in ICGN mice, a strain of mice with hereditary nephrotic syndrome

Fibrotic degeneration was examined in the kidneys of ICR-derived glomerulonephritis (ICGN) mice, a novel inbred mouse line with a hereditary nephrotic syndrome of unknown etiology considered to be a good model of human idiopathic nephrotic syndrome. In the present study, we histochemically revealed changes in accumulation of extracellular matrix (ECM) components and in localization of integrins, cellular receptors for ECM, in the kidneys of ICGN mice with the progression of renal failure. Excessive accumulation of basement membrane (laminin and collagen IV) and interstitial (type III collagen) ECM components were demonstrated in the glomeruli and tubulointerstitum of ICGN mice. Marked deposition of type I collagen and tenascin was seen only in the glomeruli of ICGN mice but not in those of ICR mice as normal controls. Increased expression of integrin alpha1-, alpha2-, alpha5- and beta1-subunits in glomeruli with fibrotic degeneration and abnormal distribution of alpha6-subunit were noted in the kidneys of ICGN mice. Excessive laminin, a ligand of alpha6beta1-integrin, was demonstrated on the tubular basement membrane, but alpha6-subunit diffusely disappeared on the basal side of the tubular epithelial cells. We presumed that abnormal integrin expression in renal tubules causes epithelial cell detachment, and consequently tubular nephropathy, and results in disorder of ECM metabolism causing excessive accumulation of ECM components in the kidneys of ICGN mice.

Localization of proliferative and apoptotic cells in the kidneys of ICR-derived glomerulonephritis (ICGN) mice

The ICR-derived glomerulonephritis (ICGN) mouse is a novel inbred mouse strain with a hereditary nephrotic syndrome, considered to be a good model of human idiopathic nephrotic syndrome and develops proteinuria, hypoproteinemia and anemia. In the present study, we compared the cell kinetics in the kidneys of ICGN mice with age-matched ICR mice as normal controls. The proliferating cells were visualized by 5-bromo-2'-deoxyuridine labeling, and apoptotic cells were determined by terminal deoxynucleotidyl transferase-mediated biotinylated deoxyuridine triphosphate nick end-labeling. Many proliferating epithelial cells of renal tubules, glomerular mesangial cells and tublointerstitial fibroblast-like cells were observed in the kidneys of ICGN mice, but no proliferating cells were seen in the kidneys of ICR mice. Apoptotic cells had round nuclei, and were observed only in the tubulointerstitium in the kidneys of ICGN mice but not in that of controls. The proliferation of renal tubular epithelial cells may represent a compensatory response, and that of mesangial and fibroblast-like cells may play a pathogenic role in nephrotic syndrome. Apoptosis in tubulointerstitial cells with round nuclei may have been erythropoietin-producing cells, and probably caused anemia.