Digenic Inheritance of a FOXC2 Mutation and Two PIEZO1 Mutations Underlies Congenital Lymphedema in a Multigeneration Family.

BACKGROUND: The lymphatic system is essential for maintaining the balance of interstitial fluid in tissues and for returning protein-rich fluids (lymph) to the bloodstream. Congenital lymphatic defects lead to accumulation of lymph in peripheral tissues and body cavities, termed primary lymphedema. To date, only a limited number of individual genes have been identified in association with primary lymphedema. However, variability of age of onset and severity of lymphatic abnormalities within some families suggests that multiple mutations or genes may be responsible, thus hampering efforts to identify individual associated genes. METHODS: Whole exome sequencing (WES) was performed in 4 members of a large multigeneration family with highly variable lymphedema and followed by Sanger sequencing for identified mutations in 34 additional family members. Genotypes were correlated with clinical and lymphangioscintigraphic phenotypes. RESULTS: WES uncovered 2 different mechanotransducer PIEZO1 mutations and one FOXC2 transcription factor mutation in various combinations. Sanger sequencing confirmed the presence/absence of the 3 variants in affected and unaffected family members and co-segregation of one or more variants with disease. Genetic profiles did not clearly correlate with the highly variable severity of lymphatic abnormalities. CONCLUSIONS: WES in lymphedema families can uncover unexpected combinations of several lymphedema-associated mutations. These findings provide essential information for genetic counseling and reveal complex gene interactions in lymphatic developmental pathways. These can offer insights into the complex spectrum of clinical and lymphatic lymphedema phenotypes and potential targets for treatment.

Sustained Release GLP-1 Agonist PT320 Delays Disease Progression in a Mouse Model of Parkinson's Disease.

GLP-1 agonists have become increasingly interesting as a new Parkinson's disease (PD) clinical treatment strategy. Additional preclinical studies are important to validate this approach and define the disease stage when they are most effective. We hence characterized the efficacy of PT320, a sustained release formulation of the long acting GLP-1 agonist, exenatide, in a progressive PD (MitoPark) mouse model. A clinically translatable biweekly PT320 dose was administered starting at 5 weeks of age and longitudinally evaluated to 24 weeks, and multiple behavioral/cellular parameters were measured. PT320 significantly improved spontaneous locomotor activity and rearing in MitoPark PD mice. "Motivated" behavior also improved, evaluated by accelerating rotarod performance. Behavioral improvement was correlated with enhanced cellular and molecular indices of dopamine (DA) midbrain function. Fast scan cyclic voltammetry demonstrated protection of striatal and nucleus accumbens DA release and reuptake in PT320 treated MitoPark mice. Positron emission tomography showed protection of striatal DA fibers and tyrosine hydroxylase protein expression was augmented by PT320 administration. Early PT320 treatment may hence provide an important neuroprotective therapeutic strategy in PD.

Rare monosomy 7 and deletion 7p at diagnosis of chronic myeloid leukemia in accelerated phase.

Clonal cytogenic evolution with the development of additional chromosomal abnormalities (ACAs) in chronic myelogenous leukemia (CML) is a marker for disease progression and is known to impact therapy and survival. The presence of ACAs has been shown to affect the responses to tyrosine kinase inhibitors (TKI) in patients with newly diagnosed CML in accelerated phase (CML-AP). We report a rare case of a CML patient who presented in CML-AP and was found to have multiple ACAs including monosomy 7, deletion 7p, trisomy 8, and an extra Philadelphia chromosome (Ph) in separate Ph-positive cell line, respectively. Six months after combined chemotherapy with TKI, the patient achieved a major cytogenetic response with disappearance of monosomy 7/deletion 7p with no major molecular response.

Exome sequencing in patients with microphthalmia, anophthalmia, and coloboma (MAC) from a consanguineous population.

Next-generation sequencing strategies have resulted in mutation detection rates of 21% to 61% in small cohorts of patients with microphthalmia, anophthalmia and coloboma (MAC), but despite progress in identifying novel causative genes, many patients remain without a genetic diagnosis. We studied a cohort of 19 patients with MAC who were ascertained from a population with high rates of consanguinity. Using single nucleotide polymorphism (SNP) arrays and whole exome sequencing (WES), we identified one pathogenic variant in TENM3 in a patient with cataracts in addition to MAC. We also detected novel variants of unknown significance in genes that have previously been associated with MAC, including KIF26B, MICU1 and CDON, and identified variants in candidate genes for MAC from the Wnt signaling pathway, comprising LRP6, WNT2B and IQGAP1, but our findings do not prove causality. Plausible variants were not found for many of the cases, indicating that our current understanding of the pathogenesis of MAC, a highly heterogeneous group of ocular defects, remains incomplete.

Sex-limited penetrance of lymphedema to females with CELSR1 haploinsufficiency: A second family.

A second multigeneration family with hereditary lymphedema (LE) secondary to a variant in the planar polarity gene, CELSR1, is described. Dominant inheritance of the variant was discovered using whole-exome sequencing and confirmed by Sanger sequencing. In contrast to heterozygous males, all heterozygous females showed LE during physical examination albeit variable in severity and age of onset. Lymphscintigraphy in affected females showed previously undescribed lymphatic abnormalities consistent with lymphangiectasia, valve dysfunction, and thoracic duct reflux.

The role of calbindin-D28k on renal calcium and magnesium handling during treatment with loop and thiazide diuretics.

Calbindin-D28k (CBD-28k) is a calcium binding protein located in the distal convoluted tubule (DCT) and plays an important role in active calcium transport in the kidney. Loop and thiazide diuretics affect renal Ca and Mg handling: both cause Mg wasting, but have opposite effects on Ca excretion as loop diuretics increase, but thiazides decrease, Ca excretion. To understand the role of CBD-28k in renal Ca and Mg handling in response to diuretics treatment, we investigated renal Ca and Mg excretion and gene expression of DCT Ca and Mg transport molecules in wild-type (WT) and CBD-28k knockout (KO) mice. Mice were treated with chlorothiazide (CTZ; 50 mg · kg(-1) · day(-1)) or furosemide (FSM; 30 mg · kg(-1) · day(-1)) for 3 days. To avoid volume depletion, salt was supplemented in the drinking water. Urine Ca excretion was reduced in WT, but not in KO mice, by CTZ. FSM induced similar hypercalciuria in both groups. DCT Ca transport molecules, including transient receptor potential vanilloid 5 (TRPV5), TRPV6, and CBD-9k, were upregulated by CTZ and FSM in WT, but not in KO mice. Urine Mg excretion was increased and transient receptor potential subfamily M, member 6 (TRPM6) was upregulated by both CTZ and FSM in WT and KO mice. In conclusion, CBD-28k plays an important role in gene expression of DCT Ca, but not Mg, transport molecules, which may be related to its being a Ca, but not a Mg, intracellular sensor. The lack of upregulation of DCT Ca transport molecules by thiazides in the KO mice indicates that the DCT Ca transport system is critical for Ca conservation by thiazides.

Preparation and Characterization of Surface Photocatalytic Activity with NiO/TiO2 Nanocomposite Structure.

This study achieved a nanocomposite structure of nickel oxide (NiO)/titanium dioxide (TiO2) heterojunction on a TiO2 film surface. The photocatalytic activity of this structure evaluated by decomposing methylene blue (MB) solution was strongly correlated to the conductive behavior of the NiO film. A p-type NiO film of high concentration in contact with the native n-type TiO2 film, which resulted in a strong inner electrical field to effectively separate the photogenerated electron-hole pairs, exhibited a much better photocatalytic activity than the controlled TiO2 film. In addition, the photocatalytic activity of the NiO/TiO2 nanocomposite structure was enhanced as the thickness of the p-NiO film decreased, which was beneficial for the migration of the photogenerated carriers to the structural surface.

Sputtered ZnO-SiO2 nanocomposite light-emitting diodes with flat-top nanosecond laser treatment.

Sputtered ZnO-SiO2 nanocomposite light-emitting diodes (LEDs) were treated using a flat-top nanosecond laser (FTNL) under room temperature. The intensity of the 376 nm electroluminescence (EL) emission of ZnO-SiO2 nanocomposite LEDs at a current of 9 mA with FTNL treatment was approximately 1.4 times greater than LEDs without FTNL treatment. Furthermore, the FTNL-treated LEDs indicated a narrower full width at half maximum of the 376 nm EL emission than those of LEDs without FTNL treatment. Thus, FTNL treatment of ZnO-SiO2 nanocomposite LEDs could induce the recrystallization of distributed ZnO nanoclusters and reduce the defects in ZnO-SiO2 nanocomposite layers.

Renal adaptation to gentamicin-induced mineral loss.

BACKGROUND: Gentamicin, a well-known nephrotoxic drug, affects calcium and magnesium homeostasis. Although gentamicin induces urinary calcium and magnesium wasting immediately, it rarely causes significant hypocalcemia or hypomagnesemia clinically. METHODS: We conducted an animal study to investigate the renal adaptation in calcium and magnesium handling after gentamicin treatment and effects on the expression of calcium and magnesium transport molecules in distal tubule. Gentamicin (40 mg/kg) was injected daily in male Sprague-Dawley rats (220-250 g) for up to 7 days. RESULTS: This treatment did not affect serum creatinine, calcium, or magnesium levels. Gentamicin induced significant hypercalciuria (14-fold) and hypermagnesiuria (10-fold) in 6 h, which was associated with upregulation of TRPV5 (175 ± 3%), TRPV6 (170 ± 4%), TRPM6 (156 ± 4%) and calbindin-D28k (174 ± 3%; all p < 0.05 vs. control). This gene upregulation was maintained with daily injection of gentamicin for 7 days. The gentamicin-induced urinary calcium loss was reduced by 80% at days 3 and 7, while magnesium loss was reduced by 52 and 57% at days 3 and 7, respectively. On the other hand, urinary loss of potassium became worse on day 7 (2-fold), and phosphorus loss worse from day 3 to day 7 (3-fold). CONCLUSION: There is a rapid adaptation to gentamicin-induced hypercalciuria and hypermagnesiuria. The upregulation of distal tubule transport molecules, TRPV5, TRPV6, TRPM6 and calbindin-D28k occurs within 6 h of gentamicin treatment. This renal adaptation prevents further mineral loss due to gentamicin treatment.

Pharmacologic recruitment of regulatory T cells as a therapy for ischemic acute kidney injury.

Regulatory T cells (Tregs) are key components of the peripheral tolerance system and have become an immunotherapeutic agent for treating inflammatory processes. This therapeutic option, however, is hampered by problems arising from isolating and expanding desirable Tregs. Here we used an alternative approach with a pharmacologic agent to stimulate Tregs to achieve immunosuppressive effects. Pretreatment of mice with the naturally occurring sphingosine N,N-dimethylsphingosine (DMS) was found to increase both tissue-infiltrating T effectors (Teffs, CD4(+)Foxp3(-)) and Tregs (CD4(+)Foxp3(+)) in the early phase of bilateral renal ischemia/reperfusion injury. DMS itself had no effects on renal function or histopathology, but rapidly and transiently increased both Teffs and Tregs and increased the expression of chemokines CXCL9, CCL5, and CXCL10 in non-ischemic kidneys (sham operation). This renoprotection was abolished by administration of the Treg suppressing agents, anti-CTLA-4 or anti-CD25 monoclonal antibodies, suggesting that Tregs play a key role in DMS-induced renoprotection. Thus, Tregs recruited to the kidney by DMS ameliorate acute kidney injury and provide a new approach to control inflammatory diseases.

Variations of dietary salt and fluid modulate calcium and magnesium transport in the renal distal tubule.

BACKGROUND: The renal distal tubule fine-tunes renal epithelial calcium transport. Dietary intake of salt and fluid varies day-to-day and the kidney adapts accordingly to maintain homeostasis. The alternations in salt and fluid balance affect calcium and magnesium transport in the distal tubule, but the mechanisms are not fully understood. METHODS: Sprague-Dawley rats were grouped into high-salt, low-salt and dehydration treatment. Daily intake, water consumption and urine output were recorded. At the end of the experiment, blood and urine samples were collected for hormonal and biochemical tests. Genetic analysis, immunoblotting and immunofluorescence studies were then performed to assess the alterations of calcium and magnesium transport-related molecules. RESULTS: High-salt treatment increased urinary sodium, calcium and magnesium excretion. Low-salt treatment and dehydration were associated with decreased urinary excretion of all electrolytes. High-salt treatment was associated with increased intact parathyroid hormone levels. A significant increase in gene expression of TRPV5, TRPV6, calbindin-D28k and TRPM6 was found during high-salt treatment, while low salt and dehydration diminished expression. These findings were confirmed with immunofluorescence studies. High-salt and low-salt intake or dehydration did not cause any significant changes in WNK1, WNK3 and WNK4. CONCLUSIONS: Alternations in salt and water intake affect renal calcium and magnesium handling. High-salt intake increases the distal delivery of the divalent cations which upregulates distal tubule calcium and magnesium transport molecules, while the opposite effects are associated with low-salt intake or dehydration.

Electroluminescence of ZnO nanocrystal in sputtered ZnO-SiO2 nanocomposite light-emitting devices.

We have demonstrated the electroluminescence (EL) of Ga:ZnO/i-ZnO-SiO2 nanocomposite/p-GaN n-i-p heterostructure light-emitting devices (LEDs). ZnO nano-clusters with sizes distributing from 2 to 7nm were found inside the co-sputtered i-ZnO-SiO2 nanocomposite layer under the observation of high-resolution transparent electron microscope. A clear UV EL at 376 nm from i-ZnO-SiO2 nanocomposite in these p-i-n heterostructure LEDs was observed under the forward current of 9 mA. The EL emission peak at 376 and 427nm of the Ga:ZnO/i-ZnO-SiO2 nanocomposite/p-GaN n-i-p heterostructure LEDs were attributed to the radiative recombination from the ZnO clusters and the Mg acceptor levels in the p-GaN layer, respectively.

Effects of cyclosporine, tacrolimus and rapamycin on renal calcium transport and vitamin D metabolism.

BACKGROUND: Abnormalities in mineral metabolism are common complications of organ transplantation. The role of immunosuppressive agents in alteration of mineral metabolism is not clear. METHODS: We conducted an animal study to investigate the effects of cyclosporine A (CsA), tacrolimus, and sirolimus on renal calcium, magnesium and vitamin D metabolism. RESULTS: CsA and tacrolimus induced a 2- to 3-fold and 1.6- to 1.8-fold increase in urinary calcium and magnesium excretion, respectively, while rapamycin had no effects on calcium, but doubled the urinary magnesium excretion. CsA and tacrolimus, but not rapamycin, elevated serum 1,25(OH)(2) vitamin D without affecting the parathyroid hormone level. CsA and tacrolimus reduced mRNA abundance in TRPV5 (CsA: 64 ± 3% of control; tacrolimus: 50 ± 3%) calbindin-D28k (CsA: 62 ± 4%; tacrolimus: 43 ± 3%), and vitamin D receptor (CsA: 52 ± 3%; tacrolimus: 58 ± 2%, all p < 0.05). Rapamycin did not affect gene expression in any of studied proteins. The immunofluorescence staining study demonstrated a 50% reduction of TRPV5 and calbindin-D28k by CsA and tacrolimus. CONCLUSION: The suppression of VDR by calcineurin inhibitors is probably the underlying mechanism of renal calcium wasting. In spite of an increased 1,25(OH)(2) vitamin D level, the kidney is not able to reserve calcium, suggesting a role of vitamin D resistance that may be related to bone loss.

Pathogenesis, diagnosis and management of paraneoplastic glomerulonephritis.

Paraneoplastic glomerulonephritis is a rare complication of malignancy that is frequently mistaken for idiopathic glomerulonephritis. Failure to recognize paraneoplastic glomerulonephritis can subject patients to ineffective and potentially harmful therapy. The pathology of paraneoplastic glomerulonephritis varies between different types of malignancies. This Review discusses the association of glomerulonephritis with both solid tumors and hematological malignancies. The pathogenetic mechanisms of many glomerular lesions seem to relate to altered immune responses in the presence of a malignancy. Studies in the Buffalo/Mna rat model of spontaneous thymoma and nephrotic syndrome indicate that polarization of the immune response toward a T-helper-2 (T(H)2) profile has an important role in the development of thymoma-associated glomerular lesions. Furthermore, overexpression of the T(H)2 cytokine interleukin 13 in rats induces minimal change disease. Such findings from experimental studies might facilitate the identification of biomarkers that can distinguish paraneoplastic glomerulonephritis from idiopathic and other secondary glomerulonephritides. This Review describes potential pathogenetic mechanisms for paraneoplastic glomerulonephritides associated with different malignancies and highlights the need for a multidisciplinary approach to the management of patients with paraneoplastic glomerulonephritis.

Site-specific expression of IQGAP1, a key mediator of cytoskeleton, in mouse renal tubules.

IQGAP1 is a multifunctional junction molecule that is involved in cell migration, proliferation, differentiation, cell polarity, and cell-cell adhesion. It is highly expressed in the kidney and has recently been identified in the glomerular basement membrane as a nephrin-associated protein. However, the distribution of IQGAP1 in renal tubular epithelial cells is unknown. We performed confocal microscopic studies to localize IQGAP1 in each nephron segment using dual immunofluorescence staining with various antibodies against segment-specific markers. We found that IQGAP1 was strongly expressed in the distal convoluted tubule (DCT), collecting duct, and macula densa and moderately in the thick ascending limb and proximal tubule. In the DCT, the IQGAP1-F-actin complex forms a comb-like structure with multiple parallel spikes sitting on the basal membrane. In the macula densa cells, IQGAP1 is strongly expressed in the apical membrane, whereas in type A intercalated cells, IQGAP1 is expressed in the basolateral membrane, where it colocalizes with anion exchanger 1, and in principal cells, it is diffusely expressed. In conclusion, we showed the expression and subcellular localization of IQGAP1 in various nephron segments. The site-specific expression pattern of this potent modulator of multiple biological pathways in the renal tubules suggests that IQGAP1 may have multiple important roles in various renal functions.

Delivery of intercellular adhesion molecule-1 antisense oligonucleotides using a topical hydrogel tissue sealant in a murine partial nephrectomy/ischemia model.

OBJECTIVES: Ischemia/reperfusion injury is a leading cause of renal damage which can be improved with antisense oligonucleotide gene therapy. We have shown that polyethylene glycol (PEG) hydrogel, which also functions as a tissue sealant, is an effective topical delivery vehicle for oligonucleotides in a murine partial nephrectomy model. The objective of this study was to use and evaluate this method against intercellular adhesion molecule-1 (ICAM-1) to prevent tissue damage. METHODS: Sixty mice underwent left upper pole partial nephrectomy with 45 minutes of warm ischemia, randomized to treatment with 50 microg ICAM-1 antisense oligonucleotides embedded in PEG hydrogel, no therapy, or sham surgery. Kidneys were harvested at 24 hours and 3, 4, and 5 days. The specimens were evaluated by quantitative real-time polymerase chain reaction (qRT-PCR) for ICAM-1 messenger ribonucleic acid (mRNA), immunohistochemical staining for ICAM-1 protein, and standard histology. RESULTS: At 24 hours, qRT-PCR and immunohistochemistry data showed a significant reduction in ICAM-1 mRNA and protein expression in the antisense group versus the ischemia group, but no difference at 3 to 5 days. Histologically there was reduced inflammation and necrosis in the cortex at 24 hours. The outer and inner medulla also showed improvement at 3 to 5 days in the antisense group as opposed to the ischemia group. CONCLUSIONS: Topical PEG hydrogel delivery of antisense ICAM-1 oligonucleotides demonstrated decreased ICAM-1 mRNA expression, reduced ICAM-1 protein staining, and decreased cellular damage. The application of gene therapy through this novel topical delivery system holds potential for a highly specific, localized method of preventing tissue damage after ischemia/reperfusion injury.

Phenotypic characteristics of bone in carbonic anhydrase II-deficient mice.

Carbonic anhydrase II (CAII)-deficient mice were created to study the syndrome of CAII deficiency in humans including osteopetrosis, renal tubular acidosis, and cerebral calcification. Although CAII mice have renal tubular acidosis, studies that analyzed only cortical bones found no changes characteristic of osteopetrosis. Consistent with previous studies, the tibiae of CAII-deficient mice were significantly smaller than those of wild-type (WT) mice (28.7 +/- 0.9 vs. 43.6 +/- 3.7 mg; p < 0.005), and the normalized cortical bone volume of CAII-deficient mice (79.3 +/- 2.2%) was within 5% of that of WT mice (82.7 +/- 2.3%; p < 0.05), however, metaphyseal widening of the tibial plateau was noted in CAII-deficient mice, consistent with osteopetrosis. In contrast to cortical bone, trabecular bone volume demonstrated a nearly 50% increase in CAII-deficient mice (22.9 +/- 3.5% in CAII, compared to 15.3 +/- 1.6% in WT; p < 0.001). In addition, histomorphometry demonstrated that bone formation rate was decreased by 68% in cortical bone (4.77 +/- 1.65 microm3/microm2/day in WT vs. 2.07 +/- 1.71 microm3/microm2/day in CAII mice; p < 0.05) and 55% in trabecular bone (0.617 +/- 0.230 microm3/microm2/day in WT vs. 0.272 +/- 0.114 microm3/microm2/day in CAII mice; p < 0.05) in CAII-deficient mice. The number of osteoclasts was significantly increased (67%) in CAII-deficient mice, while osteoblast number was not different from that in WT mice. The metaphyseal widening and changes in the trabecular bone are consistent with osteopetrosis, making the CAII-deficient mouse a valuable model of human disease.

Effects of furosemide on renal calcium handling.

Furosemide is a loop diuretic agent that has been used to treat hypercalcemia because it increases renal calcium excretion. The effect of furosemide on calcium transport molecules in distal tubules has yet to be investigated. We conducted studies to examine the effects of furosemide on renal calcium excretion and expression of calcium transport molecules in mice. Mice were administered with a single dose of furosemide (15 mg/kg) and examined 4 h later or were given twice-daily furosemide injections for 3 days. To evaluate the effects of volume depletion, drinking water was supplemented with salt. Our results showed that, in acute experiments, furosemide enhanced urinary calcium excretion, which was associated with a significant increase in mRNA levels of TRPV5, TRPV6, and calbindin-D28k but not calbindin-D9k as measured by real-time PCR (TRPV5 and TRPV6 are transient receptor potential vanilloid 5 and 6). Chronic furosemide administration induced three- to fourfold increases in urinary calcium excretion and elevated mRNA levels of TRPV5, TRPV6, calbindin-D28k, and calbindin-D9k without or with salt supplement. Similar upregulation of calcium transport molecules was observed in mice with gentamicin-induced hypercalciuria. Coadministration of chlorothiazide decreased furosemide-induced calciuria, either acutely or chronically, although still accompanied by upregulation of these transport molecules. Immunofluorescent staining studies revealed comparably increased protein abundance in TRPV5 and calbindin-D28k. We conclude that furosemide treatment enhances urinary calcium excretion. Increased abundance of calcium transport molecules in the distal convoluted tubule represents a solute load-dependent effect in response to increased calcium delivery and serves as a compensatory adaptation in the downstream segment.

Functionally improved bone in calbindin-D28k knockout mice.

In vitro studies indicate that Calbindin-D28k, a calcium binding protein, is important in regulating the life span of osteoblasts as well as the mineralization of bone extracellular matrix. The recent creation of a Calbindin-D28k knockout mouse has provided the opportunity to study the physiological effects of the Calbindin-D28k protein on bone remodeling in vivo. In this experiment, histomorphometry, microCT, and bend testing were used to characterize bones in Calbindin-D28k KO (knockout) mice. The femora of Calbindin-D28k KO mice had significantly increased cortical bone volume (60.4% +/- 3.1) compared to wild-type (WT) mice (45.4% +/- 4.6). The increased bone volume was due to a decrease in marrow cavity area, and significantly decreased endosteal perimeters (3.397 mm +/- 0.278 in Calbindin-D28k KO mice, and 4.046 mm +/- 0.450 in WT mice). Similar changes were noted in the analysis of the tibias in both mice. The bone formation rates were similar in the femoral and tibial cortical bones of both mice. microCT analysis of the trabecular bone in the tibial plateau indicated that Calbindin-D28k KO mice had an increased bone volume (35.2% +/- 3.1) compared to WT mice (24.7% +/- 4.9) which was primarily due to increased trabecular number (8.99 mm(-1) +/- 0.94 in Calbindin-D28k KO mice compared to 6.75 mm(-1) +/- 0.85 in WT mice). Bone mineral content analysis of the tibias indicated that there is no difference in the calcium or phosphorus content between the Calbindin-D28k KO and WT mice. Cantilever bend testing of the femora demonstrated significantly lower strains in the bones of Calbindin-D28k KO mice (4135 micro strain/kg +/- 1266) compared to WT mice (6973 micro strain/kg +/- 998) indicating that the KO mice had stiffer bones. Three-point bending demonstrated increased failure loads in bones of Calbindin-D28k KO mice (31.6 N +/- 2.1) compared to WT mice (15.0 N +/- 1.7). In conclusion, Calbindin-D28k KO mice had increased bone volume and stiffness indicating that Calbindin-D28k plays an important role in bone remodeling.