Combined Ingestion of Tea Catechin and Citrus ß-Cryptoxanthin Improves Liver Function via Adipokines in Chronic Obesity.

Recently, there has been an increase in the number of obese individuals, which has elevated the risk of related diseases. Although several studies have been performed to develop a definitive treatment for obesity, no solution has yet been achieved. Recent evidence suggests that tea catechins possess antiobesity effects; however, an impractical amount of catechin may be required to achieve antiobesity effects in humans. Moreover, studies are yet to elucidate the effects of the combined treatment of tea catechins with other substances. Here, we investigated the synergistic effects of catechins and ß-cryptoxanthin in high-calorie diet-induced mice. Combined treatment with catechins and ß-cryptoxanthin significantly suppressed obesity-induced weight gain and adipocyte size and area, restoring serum parameters to normal. Additionally, combined treatment with catechins and ß-cryptoxanthin suppressed inflammatory responses in adipocytes, restored adiponectin levels to normal, protected the liver against obesity-induced damage, and restored normal liver function. Moreover, activin E level was restored to normal, possibly affecting the energy metabolism of brown adipocytes. Overall, these results suggest that the combined ingestion of tea catechins and ß-cryptoxanthin was not only effective against obesity but may also help to prevent obesity-related diseases, such as diabetes and cardiovascular diseases.

Molecules Affecting Brain Development and Nervous System.

Brain development is the biological process through which neurons are produced [...].

Factors contributing to carboplatin blockade and interruption in its route of administration in paclitaxel-carboplatin therapy.

The interruption of anticancer infusion processes in patients undergoing chemotherapy may affect their quality of life and the efficacy and safety of the therapy. We experienced several interruptions of carboplatin infusion in multiple patients receiving paclitaxel-carboplatin combination therapy. Therefore, we investigated the causes of these interruptions. The filter and catheter surfaces were evaluated by scanning electron microscopy. Moreover, using a texture analyzer, the mechanical strengths of catheter-attached syringes were compared pre- and post-administration. We observed that the syringe pushing force requirement was higher following dripping failure. However, precipitates were not evident on the filter surfaces, regardless of the dripping failure route. In this case, some of the drug adhered to the catheters' surfaces and interrupted the carboplatin titration. Consequently, in patients receiving combination therapy with paclitaxel and carboplatin, and experiencing interruptions in carboplatin infusion, attention should be paid to the catheter.

Anti-Obesity and Anti-Inflammatory Synergistic Effects of Green Tea Catechins and Citrus ß-Cryptoxanthin Ingestion in Obese Mice.

Chronic obesity causes various diseases, leading to an urgent need for its treatment and prevention. Using monosodium-glutamate-induced obesity mice, the present study investigated the synergistic obesity-reducing effects of tea catechins and the antioxidant ß-cryptoxanthin present in mandarin oranges. The results show that the obese mice that ingested both tea catechin and ß-cryptoxanthin for 4 weeks had a significantly decreased body weight, with no difference in body weight compared with control mice. Moreover, the blood biochemical test results were normal, and the body fat percentage was significantly decreased according to the histopathological analysis. Additionally, the abundance of M1 macrophages, which release pro-inflammatories, was significantly reduced in adipose tissue. Indeed, a significant decrease was detected in M1-macrophage-secreted tumor necrosis factor-alpha levels. Meanwhile, M2 macrophage levels were recovered, and adiponectin, which is released from adipocytes and involved in suppressing metabolic syndrome, was increased. Collectively, these results suggest that the combination of tea catechins and antioxidant foods can alleviate chronic obesity, indicating that a combination of various ingredients in foods might contribute to reducing chronic obesity.

Severe Acute Liver Dysfunction Induces Delayed Hepatocyte Swelling and Cytoplasmic Vacuolization, and Delayed Cortical Neuronal Cell Death.

Liver dysfunction is the main cause of hepatic encephalopathy. However, histopathological changes in the brain associated with hepatic encephalopathy remain unclear. Therefore, we investigated pathological changes in the liver and brain using an acute hepatic encephalopathy mouse model. After administering ammonium acetate, a transient increase in the blood ammonia level was observed, which returned to normal levels after 24 h. Consciousness and motor levels also returned to normal. It was revealed that hepatocyte swelling, and cytoplasmic vacuolization progressed over time in the liver tissue. Blood biochemistry also suggested hepatocyte dysfunction. In the brain, histopathological changes, such as perivascular astrocyte swelling, were observed 3 h after ammonium acetate administration. Abnormalities in neuronal organelles, especially mitochondria and rough endoplasmic reticulum, were also observed. Additionally, neuronal cell death was observed 24 h post-ammonia treatment when blood ammonia levels had returned to normal. Activation of reactive microglia and increased expression of inducible nitric oxide synthase (iNOS) were also observed seven days after a transient increase in blood ammonia. These results suggest that delayed neuronal atrophy could be iNOS-mediated cell death due to activation of reactive microglia. The findings also suggest that severe acute hepatic encephalopathy causes continued delayed brain cytotoxicity even after consciousness recovery.

SEM Observation of the Filter after Administration of Blinatumomab: A Possibility of Leakage during Home Administration Using a Portable Infusion Pump.

Blinatumomab (Blincyto® injection solution) is classified as a bispecific T-cell engaging (BiTE) antibody and is intended for the treatment of relapsed/refractory acute lymphoblastic leukemia. It requires continuous infusion to maintain therapeutic levels. Therefore, it is often administered at home. Monoclonal antibodies, which are administered intravenously, have the potential to leak depending on the nature of the administration devices. Therefore, we investigated device-associated causes of blinatumomab leakage. We observed no apparent changes to the filter and its materials after exposure to the injection solution and surfactant. From scanning electron microscopic images, precipitate on the surface of the filters was observed after physical stimulation of the injection solution. Therefore, physical stimulations should be avoided during the prolonged administration of blinatumomab. In conclusion, the findings of this study assist in the safe administration of antibodies using portable infusion pumps, taking into consideration the composition of drug excipients and the choice of filter type and structure.

Immunohistochemical and Immunoelectron Microscopical Distribution of MEGF8 in the Mouse Central Nervous System.

Mutations in multiple epidermal growth factor-like domain 8 (MEGF8), a multidomain transmembrane protein encoded by a gene conserved across species, cause Carpenter's syndrome, which is associated with learning disabilities, mental health issues, and left-right patterning abnormalities. MEGF8 interacts with MGRN1, a protein that functions as an E3 ubiquitin ligase and is involved in multiple physiological and pathological processes. However, the mechanism underlying the distribution of MEGF8 in the central nervous system (CNS) and its cellular and subcellular locations remain unknown. This study aimed to map MEGF8 in the mouse CNS using a new antibody. We discovered that MEGF8 was distributed in the majority of neuronal cell somata across most CNS regions. High levels of MEGF8 were expressed in the neuropils of the CNS gray matter. Immunoelectron microscopy showed that MEGF8 was present in the synapses and around the outer mitochondrial membrane. These findings show that MEGF8 is uniformly distributed throughout the mouse CNS, and its distribution indicates that it plays a substantial role in synaptic and mitochondrial functions. To the best of our knowledge, this is the first study to document MEGF8 distribution in the CNS.

Exposure to Heated Tobacco Products Aerosol Causes Acute Stress Responses in the Lung of Mouse.

In the present study, we evaluated the acute response of mice exposed to IQOS aerosol, a brand-name heated tobacco product (HTP), in the lung tissue. First, the thiobarbituric acid-reactive substances (TBA-RS) value was measured as an index to assess oxidative stress, and a significant increase was observed after exposure, followed by a significant increase in the total lung GSH concentration. The stress responses induced by IQOS aerosols was then analyzed by focusing on the changes in Nrf2 and ATF4, which are transcription factors that induce the expression of genes involved in GSH biosynthesis or metabolism. Although Nrf2 activation was not observed, significant accumulation of ATF4 in the nuclear fraction was noted three hours after exposure to IQOS aerosols. Upon an examination of changes in factors in the GSH biosynthetic system, a significant increase in cystine concentration in the lung tissue was measured, and an increase in xCT expression level was observed in the cell membrane fraction three-six hours after IQOS exposure. Furthermore, characteristic changes in HO-1, a stress-response protein regulated by ATF4, was discovered six hours after IQOS exposure. Moreover, analysis of the upstream ATF4 regulatory system revealed that phosphorylation of eIF2α was enhanced in the lung cytoplasmic fraction three hours after exposure to IQOS aerosols. These findings suggest that ER stress might be induced as an early response to IQOS aerosol exposure, accompanied by the activation of the eIF2α-ATF4 axis. These intracellular changes have also been reported after exposure to combustible cigarette smoke. Thus, the acute response found in the lungs of mice in the present study demonstrate that the inhalation of aerosols from IQOS elicits a biological response similar to that of combustible cigarette smoke. In conclusion, our results provide evidence that the biological effects of HTPs, such as IQOS, cannot be ignored in the lungs.

Distribution and Localization of Mahogunin Ring Finger 1 in the Mouse Central Nervous System.

Mahogunin ring finger 1 (MGRN1), an E3 ubiquitin, is involved in several physiological and neuropathological processes. Although mgrn1 mRNA is widely distributed in the central nervous system (CNS), detailed information on its cellular and subcellular localization is lacking and its physiological role remains unclear. In this study, we aimed to determine the distribution of MGRN1 in the mouse CNS using a newly produced antibody against MGRN1. We found that the MGRN1 protein was expressed in most neuronal cell bodies. An intense MGRN1 expression was also observed in the neuropil of the gray matter in different regions of the CNS, including the main olfactory bulb, cerebral cortex, caudate, putamen, thalamic nuclei, hypothalamic nuclei, medial eminence, superior colliculus, hippocampus, dentate gyrus, and spinal cord. Contrastingly, no MGRN1 expression was observed in glial cells. Double fluorescence and immunoelectron microscopic analyses revealed the intracellular distribution of MGRN1 in pre-synapses and near the outer membrane of the mitochondria in neurons. These findings indicate that MGRN1 is more widely expressed throughout the CNS; additionally, the intracellular expression of MGRN1 suggests that it may play an important role in synaptic and mitochondrial functions.

Effects of Smart Drugs on Cholinergic System and Non-Neuronal Acetylcholine in the Mouse Hippocampus: Histopathological Approach.

In recent years, people in the United States and other countries have been using smart drugs, called nootropic or cognitive enhancers, to improve concentration and memory learning skills. However, these drugs were originally prescribed for attention-deficit hyperactivity disorder and dementia, and their efficacy in healthy people has not yet been established. We focused on acetylcholine in the hippocampus, which is responsible for memory learning, and elucidate the long-term effects of smart drugs on the neural circuits. Smart drugs were administered orally in normal young mice for seven weeks. The hippocampus was sectioned and compared histologically by hematoxylin and eosin (HE) staining, immunohistochemistry for acetylcholine, and immunoelectron microscopy. There were no significant changes in acetylcholinesterase staining. However, in HE, we found perivascular edema, and choline acetyltransferase staining showed increased staining throughout the hippocampus and new signal induction in the perivascular area in the CA3, especially in the aniracetam and α-glyceryl phosphoryl choline group. Additionally, new muscarinic acetylcholine receptor signals were observed in the CA1 due to smart drug intake, suggesting that vasodilation might cause neuronal activation by increasing the influx of nutrients and oxygen. Moreover, these results suggest a possible new mechanism of acetylcholine-mediated neural circuit activation by smart drug intake.

Severe Acute Hepatic Dysfunction Induced by Ammonium Acetate Treatment Results in Choroid Plexus Swelling and Ventricle Enlargement in the Brain.

Hepatic encephalopathy is a major cause of liver failure. However, the pathophysiological role of ventricle enlargement in brain edema remains unclear. Here, we used an acute hepatic encephalopathy mouse model to examine the sequential pathological changes in the brain associated with this condition. We collected tissue samples from experimental animals treated with ammonium acetate at 3 and 24 h post-injection. Despite the normalization of the animal's ammonia levels, samples taken at 24 h after injection exhibited distinct enlargement of lateral ventricles. The choroid plexus samples obtained at 3 h post-ammonium acetate treatment indicated enlargement; however, this swelling was reduced at the later timepoint. The aquaporin-1 proteins that regulate the choroid plexus were localized both in the apical membrane and the cytoplasm of the epithelia in the control; however, they translocated to the apical membranes of the epithelia in response to ammonia treatment. Therefore, severe acute hepatic encephalopathy induced by ammonium acetate administration caused enlargement of the ventricles, through swelling of the choroid plexus and aquaporin-1 transport and aggregation within the apical membranes.

Endocrine secretory granule production is caused by a lack of REST and intragranular secretory content and accelerated by PROX1.

Endocrine secretory granules (ESGs) are morphological characteristics of endocrine/neuroendocrine cells and store peptide hormones/neurotransmitters. ESGs contain prohormones and ESG-related molecules, mainly chromogranin/secretogranin family proteins. However, the precise mechanism of ESG formation has not been elucidated. In this study, we experimentally induced ESGs in the non-neuroendocrine lung cancer cell line H1299. Since repressive element 1 silencing transcription factor (REST) and prospero homeobox 1 (PROX1) are closely associated with the expression of ESG-related molecules, we edited the REST gene and/or transfected PROX1 and then performed molecular biology, immunocytochemistry, and electron and immunoelectron microscopy assays to determine whether ESG-related molecules and ESGs were induced in H1299 cells. Although chromogranin/secretogranin family proteins were induced in H1299 cells by knockout of REST and the induction was accelerated by the PROX1 transgene, the ESGs could not be defined by electron microscopy. However, a small number of ESGs were detected in the H1299 cells lacking REST and expressing pro-opiomelanocortin (POMC) by electron microscopy. Furthermore, many ESGs were produced in the REST-lacking and PROX1- and POMC-expressing H1299 cells. These findings suggest that a lack of REST and the expression of genes related to ESG content are indispensable for ESG production and that PROX1 accelerates ESG production.Trial registration: Not applicable.

Attractin deficiency causes metabolic and morphological abnormalities in slow-twitch muscle.

Skeletal muscle fibers are classified as slow-twitch and fast-twitch fibers, which have different reactive oxygen species (ROS) metabolism and mitochondrial biogenesis. Recently, Attractin (Atrn), which encodes secreted (sAtrn) and transmembrane (mAtrn)-type proteins, has been shown to be involved in free radical scavenging. Although Atrn has been found in skeletal muscle, little is known about the expression levels and function of Atrn in each muscle fiber type. Therefore, we investigate sAtrn and mAtrn expression levels in the slow-twitch soleus (sol) and fast-twitch extensor digitorum longus (EDL) muscles as well as the morphology and expression levels of antioxidant enzymes and functional mitochondrial markers using Atrn-deficient muscles. Both types of Atrn were expressed in the sol and EDL. mAtrn was mainly expressed in the adult sol, whereas sAtrn expression levels did not differ between muscle types. Moreover, mAtrn in the sol was abundantly localized in the subsarcolemmal area, especially in the myoplasm near mitochondria. Atrn-deficient Zitter rats showed muscle fiber atrophy, myofibril misalignment, mitochondrial swelling and vacuolation in the sol but not EDL. Furthermore, the Atrn-deficient sol exhibited a marked reduction in antioxidant enzyme SOD1, GPx1, catalase and Prx6 and mitochondrial functional protein, UCP2, expression. Even Atrn-deficient EDL showed a significant reduction in Prx3, Prx6, UCP2 and UCP3 expression. These data indicate that Atrn-deficiency disturbs ROS metabolism in skeletal muscles. In particular, mAtrn is involved in metabolism in the slow-twitch sol muscle and mAtrn-deficiency may cause ROS imbalance, resulting in morphological abnormalities in the muscle.

Minocycline prevents and repairs the skin disorder associated with afatinib, one of the epidermal growth factor receptor-tyrosine kinase inhibitors for non-small cell lung cancer.

BACKGROUND: While epidermal growth factor receptor (EGFR)-tyrosine kinase inhibitors (TKIs) exert a breakthrough effect, the incidence of skin disorders as a side effect has significantly reduced patients' quality of life. This study aimed to develop a treatment for inflammatory ulcers as one of the side effects of afatinib (Giotrif®), a second-generation EGFR-TKI, and established a skin disorder mouse model to investigate the protective effect of minocycline. METHODS: First, under inhalation anesthesia with isoflurane, the back of a male ddy mouse was shaved, and afatinib petrolatum was applied alone or in combination with minocycline to observe the state of the skin and measure transepidermal water transpiration (TEWL). Next, afatinib was administered orally to mice, and minocycline petrolatum was applied to observe whether the skin disorder was prevented and its effect on repair of the skin disorder. RESULTS: Skin injury occurred on the back of the mouse following afatinib (1 mg/g in petrolatum) application, and scab formation was observed. Application of minocycline prevented and improved the skin disorder caused by afatinib. When the minocycline-petrolatum mixture was applied to the mouse that developed the skin disorder, a significant improvement in TEWL was observed, and skin repair was observed macroscopically. CONCLUSIONS: These results suggest that minocycline petrolatum applied locally prevents and repairs afatinib-induced skin disorders of non-small cell lung cancer patients. Histological examination of skin has provided insights into the mechanism of the occurrence of afatinib-related skin disorder and suggested the efficacy of minocycline topical application in clinical practice.

Minocycline Alleviates Cluster Formation of Activated Microglia and Age-dependent Dopaminergic Cell Death in the Substantia Nigra of Zitter Mutant Rat.

Microglial activation is a component of neurodegenerative pathology. Here, we examine whether activated microglia participate in age-related dopaminergic (DA) cell death in the substantia nigra pars compacta (SNc) of the zitter (zi/zi) rat, a mutant characterized by deletion of the attractin gene. Confocal microscopy with double-immunohistochemical staining revealed activated microglia-formed cell-clusters surrounding DA neurons in the SNc from 2 weeks after birth. An immunoelectron microscopic study showed that the cytoplasm of activated microglia usually contains phagosome-like vacuoles and lamellar inclusions. Expression levels of the pro-inflammatory cytokines interleukin-1ß (IL-1ß), tumor necrosis factor-α (TNF-α) and inducible nitric oxide synthase (iNOS) were increased in the midbrain of 2-month-old zi/zi rats. Chronic treatment with the anti-inflammatory agent minocycline altered the morphology of the microglia, reduced cluster formation by the microglia, and attenuated DA cell death in the SNc, and reduced the expression of IL-1ß in the midbrain. These results indicate that activated microglia, at least in part and especially at the initial phase, contribute to DA cell death in the SNc of the zi/zi rat.

Analysis of inline-filter blockage with trastuzumab formulation using scanning-electron microscopy.

The instability of pharmaceutical monoclonal antibodies are affected by physical stimuli including, temperature, denaturant, surfactant, stirring, solid phase adsorption, oxidation, and ultraviolet rays. Clinically, we frequently experience precipitation during preparation of several pharmaceutical monoclonal antibodies for cancer. Although it is possible to remove precipitates in the injection solution during the preparation procedure, potential filter blockade during administration remains a problem with adverse effects on the quality of life of patients. Therefore we sought to investigate factors contributing to this phenomenon. To closely observed the mechanisms involved in blockade of filters during trastuzumab preparation, we prepared samples under the same conditions used in clinical practice and observed them comprehensively. The precipitates that caused filter blockade were observed when the samples were vigorously shaken and left for several hours after dissolving. The precipitates were identified as proteins. The vigorous shaking caused contact between the protein and air, which induced protein precipitation caused by the surfactants derived from the foam formation. We discovered that the external stimulation may cause the instability of monoclonal antibody preparations and, so, it is important for procedures to be as rapid to avoid precipitate formation as much as possible.

Small intestine barrier function failure induces systemic inflammation in monosodium glutamate-induced chronically obese mice.

Chronic obesity has increased worldwide, in conjunction with type 2 diabetes. Chronic obesity causes systemic inflammation that may result in functional deterioration of the gastrointestinal barrier. However, gastrointestinal conditions associated with chronic obesity have not been comprehensively investigated. The purpose of this study was to evaluate morphological changes in small intestine barrier structures during chronic obesity. A mouse model of chronic obesity induced by monosodium glutamate treatment was established. At postnatal week 15, pathological changes including in small intestinal epithelial cells were analyzed in chronically obese mice compared with controls. Numerous gaps were identified between small intestinal epithelial cells in chronically obese mice, and levels of both desmosomal and tight junction proteins were significantly lower in their small intestinal epithelial cells. Moreover, in chronically obese mice, a significant increase in the number of intestinal inflammatory cells, particularly macrophages, was observed; in addition, blood samples from the mouse model show an increase in markers of inflammation, tumor necrosis factor-alpha and interleukin-1-beta. These findings suggest that functional deterioration of adhesion structures between small intestinal epithelial cells causes gastrointestinal barrier function failure, leading to a rise in intestinal permeability to blood vessels and consequent systemic inflammation, characterized by macrophage infiltration.

Behavioral, hormonal, and neurochemical outcomes of neonatal repeated shaking brain injury in male adult rats.

It is well known that an abusive environment in childhood is related to individual anxiety behavior in adulthood. Though an imbalance of adrenocorticosteroid receptors and a dysfunction of monoaminergic neuron systems have been proposed, the underlying mechanisms are not fully understood. To address these problems, we recently developed a new model of shaking brain injury (SBI) in neonatal rats. These model rats showed transient microhemorrhages in the gray matter of the cerebral cortex and hippocampus. Using this model, we assessed the effects of neonatal repeated mild SBI on subsequent behavior and the stress response, and we further examined the possible contribution of adrenocorticosteroid receptors in the hippocampus and central monoaminergic neuron systems mediating such abnormalities. Behavioral screening examination with a novel open-field test showed that the rats with postnatal day (P) 3-7 shaking had significantly reduced locomotor activity and exploration behaviors than those with late (P8-14) shaking periods, indicating a critical period for neonatal SBI. In the elevated plus maze (EPM) and the light/dark transition (L/D) tests, the model rats spent less time in the open arm of the EPM and the light box of the L/D test, indicating anxiety-like behavior as adults. In adults, the novel EPM-induced adrenocorticotrophic hormone (ACTH) and corticosterone (CORT) responses were significantly increased by neonatal SBI. Further experiments showed that the expression of mineralocorticoid receptor (MR), but not glucocorticoid receptor (GR), was significantly downregulated in the hippocampus of this model rat. These results suggest that neonatal SBI-induced downregulation of MRs in the hippocampus attenuates negative feedback of the hypothalamic-pituitary-adrenal (HPA) axis, which results in abnormal secretion of ACTH and CORT. Furthermore, the neurochemical analysis showed that shaken rats had higher dopamine (DA), serotonin (5-HT), 5-hydroxyindolacetic acid (5-HIAA), and noradrenaline (NA) levels in the dorsal part of the medial prefrontal cortex (dmPFC). In the amygdala, higher 5-HIAA and lower NA levels were observed. Both areas are known to be anxiety and stress-related. Taken together, the effects of neonatal SBI on the monoaminergic systems may also be involved in the changes of behavioral and hormonal responses in this model.

Role of neuronal nitric oxide synthase in slowly progressive dopaminergic neurodegeneration in the Zitter rat.

Neuronal nitric oxide synthase (nNOS) is involved in nigrostriatal dopaminergic (DA) neurodegeneration. However, little is known about the distribution patterns and functions of nNOS in slowly progressive DA neurodegeneration. Here we describe the spatiotemporal change in nNOS expression over the course of neurodegeneration and the effect of short- or long-term treatment with the nNOS inhibitor, 7-nitroindazole (7-NI), in zitter (zi/zi) rats. In the substantia nigra pars compacta (SNc), nNOS expression was significantly increased with progression of neurodegeneration. nNOS-immunoreactive (ir) cells were in the vicinity of tyrosine hydroxylase-ir (TH-ir) DA neurons, and some of these cells were also positive for calbindin. nNOS in the caudate-putamen (CPu) showed little difference during progression of neurodegeneration. However, immunoelectron microscopic analysis revealed that abundant TH-ir fibers in the CPu were degenerated due to compression by vacuoles that contained swollen neuronal and glial elements. Additionally, lipid peroxidation as a marker of membrane oxidation was significantly increased in zi/zi rats. Short-term 7-NI treatment attenuated the increase in lipid peroxidation and inhibited the vacuolation in the CPu. Moreover, long-term 7-NI treatment significantly protected TH-ir neurons in the SNc, and TH-ir fibers and DA contents in the CPu. These results show that nNOS exacerbates slowly progressive DA neurodegeneration, and the neuroprotective effects of 7-NI may result from suppression of membrane oxidation that causes abnormal membrane structures in zi/zi rats.

Effects of the differential expression of ZO-1 and ZO-2 on podocyte structure and function.

Glomerular podocytes in the kidney originate from columnar epithelial cells possessing tight junctions. During podocyte differentiation, tight junctions are replaced by slit diaphragms, which are formed between foot processes and function as a blood filtration barrier. Although the expression of most tight junction components is suppressed during podocyte differentiation, several components, including ZO-1 and ZO-2, are consistently expressed. We recently showed that podocyte-specific deletion of ZO-1 gene impaired slit diaphragm formation, leading to proteinuria and glomerular sclerosis. Here, we address the relevance of ZO-2, whose sequence is highly similar to ZO-1, in the maintenance of the structure and function of podocytes. In glomerular development, the spatiotemporal expression of ZO-2 was similar to that of ZO-1 until the capillary loop stage. Subsequently, the distribution patterns of ZO-1 and ZO-2 diverged at the maturation stage, when slit diaphragms are formed. This divergence could partly rely on the ability of ZO-2 to interact with the slit diaphragm membrane proteins. Podocyte-specific deletion of the ZO-2 gene did not cause overt defects; however, double knockout of ZO-1 and ZO-2 genes accelerated the defects observed in ZO-1 knockout mice. These results suggest that ZO-2 plays supportive roles in the ZO-1-dependent regulation of podocyte filtration barrier.