A multi-institutional study found a possible role of anti-nephrin antibodies in post-transplant focal segmental glomerulosclerosis recurrence.

Possible roles of anti-nephrin antibodies in post-transplant recurrent focal segmental glomerulosclerosis (FSGS) have been reported recently. To confirm these preliminary results, we performed a multi-institutional study of 22 Japanese pediatric kidney transplant recipients with FSGS including eight genetic FSGS and 14 non-genetic (presumed primary) FSGS. Eleven of the 14 non-genetic FSGS patients had post-transplant recurrent FSGS. Median (interquartile range) plasma levels of anti-nephrin antibodies in post-transplant recurrent FSGS measured using ELISA were markedly high at 899 (831, 1292) U/mL (cutoff 231 U/mL) before transplantation or during recurrence. Graft biopsies during recurrence showed punctate IgG deposition co-localized with nephrin that had altered localization with increased nephrin tyrosine phosphorylation and Src homology and collagen homology A expressions. Graft biopsies after remission showed no signals for IgG and a normal expression pattern of nephrin. Anti-nephrin antibody levels decreased to 155 (53, 367) U/mL in five patients with samples available after remission. In patients with genetic FSGS as in those with non-genetic FSGS without recurrence, anti-nephrin antibody levels were comparable to those of 30 control individuals, and graft biopsies had no signals for IgG and a normal expression pattern of nephrin. Thus, our results suggest that circulating anti-nephrin antibodies are a possible candidate for circulating factors involved in the pathogenesis of post-transplant recurrent FSGS and that this may be mediated by nephrin phosphorylation. Larger studies including other ethnicities are required to confirm this finding.

Partial bladder transplantation with en bloc kidney transplant-long-term, 17 years, the outcome of a "bladder patch technique".

A transplant of a portion of the bladder with an en bloc kidney from a 2-year-old donor was previously reported in a 12-month-old girl due to her extremely small bladder. Bilateral kidneys were transplanted en bloc with their ureters connected to a patch of the donor bladder (bladder patch technique). The long-term outcomes and complications of this technique have not been documented. Here, we report a long-term, 17-year follow-up of this patient with an evaluation of whole bladder functions at 18 years of age. The patient has had no episodes of urinary tract infections. Cystoscopy showed a viable transplanted bladder with a well-perfused mucosa. We observed that the native bladder has stretched over time, forming more than half of the bladder wall. Urodynamic studies showed preserved bladder compliance at 43 mL/cmH2O, and native bladder contractility was preserved. Prolonged voiding time and postvoid residual urine were also observed. These findings were suggestive of detrusor underactivity. No reflux across the donor ureterovesical junctions was observed. The recipient was instructed to continue timed voiding and double voiding to empty the bladder. In conclusion, en bloc kidney transplantation with a bladder patch is a feasible and safe option for kidney transplant recipients with a small bladder capacity.

Clinical Course of Nonresponders With Recurrent Focal Segmental Glomerulosclerosis After Pediatric Kidney Transplantation: A Retrospective Multicenter Study.

BACKGROUND: Primary focal segmental glomerulosclerosis (FSGS) frequently recurs after kidney transplantation and is associated with poor graft survival. Patients who do not achieve remission (nonresponders) have an especially poor graft survival. However, the characteristics that may affect graft survival in nonresponders are unknown. This study aimed to determine the clinical characteristics associated with graft survival in nonresponders. METHODS: We retrospectively collected the clinical records of patients with FSGS and an age at onset <16 years who experienced posttransplant recurrence of FSGS at six hospitals in Japan from 1993 to 2018. RESULTS: Eight nonresponders with recurrent FSGS were enrolled in this study. The median time to recurrence after kidney transplantation was 1 day (interquartile range, 1-2 days). All patients received therapeutic plasma exchange and methylprednisolone pulse therapy. Rituximab was used as an add-on therapy in three patients. Five patients lost their graft within 2 years after kidney transplantation (rapid group). In contrast, three patients had much longer graft survival (nonrapid group). We compared the clinical characteristics of the rapid and nonrapid groups. Proteinuria tended to be lower in the nonrapid group at the third and subsequent months of therapy. The rapid group had persistent nephrotic syndrome. The rate of reduction in proteinuria was lower in the rapid group than in the nonrapid group. CONCLUSIONS: Our study suggests that persistent nephrotic syndrome and a low rate of reduction in proteinuria may predict rapid progression to graft failure in nonresponders.

A nationwide survey of MYH9-related disease in Japan.

BACKGROUND: MYH9-related disease (MYH9-RD) is characterized by congenital macrothrombocytopenia, Döhle body-like granulocyte inclusions, and nephropathy, which may progress to end-stage kidney disease (ESKD). However, information on the effects of renin-angiotensin system (RAS) inhibitors on kidney survival is currently lacking and the outcomes of kidney replacement therapy (KRT) in MYH9-RD are largely unknown. METHODS: We conducted a cross-sectional nationwide survey by sending questionnaires to 145 institutions in Japan and analyzed data for 49 patients. RESULTS: The median patient age was 27 years. Genetic analysis was performed in 37 (76%) patients. Twenty-four patients (65%) had MYH9 variants affecting the motor domain of non-muscle myosin heavy chain-IIA, and these patients had poorer kidney survival than those with variants affecting the tail domain (P = 0.02). There was no significant difference in kidney survival between patients treated with and without RAS inhibitors. Hemodialysis and peritoneal dialysis were performed in 16 and 7 patients, respectively. There were no major bleeding complications during the perioperative period or during follow-up, except for one patient. Most of the 11 patients who underwent kidney transplantation required perioperative red cell concentrate transfusions, but there was no graft loss during the median posttransplant observational period of 2.0 (interquartile range, 1.3-6.8) years. CONCLUSION: Our study demonstrated no beneficial effect of RAS inhibitors on kidney function in patients with MYH9-RD, indicating the need for further studies with more patients. All modalities of KRT are feasible options for MYH9-RD patients who progress to ESKD, with adequate attention to bleeding complications.

Children and adolescents with severe motor and intellectual disabilities who underwent kidney transplantation.

BACKGROUND: Kidney transplantation (KT) in children and adolescents with severe motor and intellectual disabilities (SMID) has been a topic of controversy. A multicenter study in Japan showed that KT was not contraindicated for children with multiple handicaps, but no consensus has been reached on KT for patients with SMID. This study aimed to determine whether KT is a viable treatment option for children and adolescents with SMID. METHODS: A single-center, retrospective study was conducted on children and adolescents with SMID who underwent KT. SMID was defined based on Oshima's classification. Clinical information was collected through a review of medical records. RESULTS: Of 453 children and adolescents who underwent KT between 1983 and 2023 in our institution, six (1.3%) patients with SMID were identified. One patient received KT twice. All patients underwent living KT. Five patients used medical devices, including gastrostomy and a ventriculoperitoneal shunt, prior to KT. Perioperative complications, including hemothorax related to central venous catheter insertion, ventilator-associated pneumonia, and common iliac artery thrombosis requiring graftectomy, occurred in three patients. One patient required vesicostomy owing to refractory urinary tract infection. There was no significant difference in the graft survival rate between patients with SMID and those without SMID. One patient developed graft failure and died after selecting conservative kidney management. CONCLUSION: Our study showed a favorable graft survival in children and adolescents with SMID who underwent KT. Although careful perioperative management and continued medical care are required, KT may be a viable option for these patients.

Pioglitazone enhances proteinuria reduction in complicated pediatric nephrotic syndrome.

BACKGROUND: Nephrotic syndrome (NS) is a common pediatric kidney disease, yet current treatments for complicated NS are only partially effective and have significant toxicity. There is no Food and Drug Administration (FDA)- or European Medicines Agency (EMA)-approved safe and effective treatment for NS. Thiazolidinediones (TZDs) have been shown to reduce proteinuria in both diabetic and non-diabetic kidney disease and in preclinical studies to directly protect podocytes from injury and reduce proteinuria. Here, we report on the potential utility of the addition of the TZD pioglitazone (PIO) to enhance proteinuria reduction in 8 children and young adults with steroid dependent NS and steroid resistant NS. METHODS: Clinical data were analyzed in comparable time periods before and after the addition of PIO to their medical regimens. Eight NS patients with minimal change NS (n = 2), focal segmental glomerulosclerosis (FSGS) (n = 4), or collapsing FSGS (n = 2) were evaluated. RESULTS: Prior to PIO initiation, all children and young adults had already received multiple immunosuppressive medications (mean = 3.75). Five of eight patients (63%; "Responders") had notable proteinuria reduction within 1 month of PIO initiation (62% reduction; P = 0.04) and normalization within 6 months (97% reduction; P = 0.04). PIO-related benefits among the responders included notable increases in serum albumin (2.5 to 3.7 g/dl; P = 0.08), dramatic reductions in hospitalizations for IV albumin infusions and diuresis (11 to 0; P < 0.01), and considerable reduction in total immunosuppression (43% reduction; P > 0.1). Importantly, no patients experienced any adverse events attributable to PIO during a total of 136 patient-months of treatment. CONCLUSIONS: While confirmatory safety and efficacy studies are needed, these findings suggest pioglitazone (a non-immunosuppressive drug) may be useful to enhance proteinuria reduction in some children and young adults with complicated NS. A higher resolution version of the Graphical abstract is available as Supplementary information.

Precise clinicopathologic findings for application of genetic testing in pediatric kidney transplant recipients with focal segmental glomerulosclerosis/steroid-resistant nephrotic syndrome.

BACKGROUND: Establishing a molecular genetic diagnosis of focal segmental glomerulosclerosis (FSGS)/steroid-resistant nephrotic syndrome (SRNS) can be useful for predicting post-transplant recurrence. Monogenic causes are reportedly present in approximately 20-30% of patients with FSGS/SRNS. However, the characteristics of patients who are likely to have a monogenic cause remain to be determined. METHODS: Pediatric recipients with SRNS and/or biopsy-proven FSGS who underwent their first kidney transplantation at our center between 1999 and 2019 were analyzed. Patients with secondary FSGS/SRNS were excluded. The recipients were divided into three groups: familial/syndromic, presumed primary, and undetermined FSGS/SRNS. Patients who met all of the following criteria were categorized as having presumed primary FSGS/SRNS: (i) nephrotic syndrome, (ii) complete or partial remission with initial steroid therapy and/or additional immunosuppressive therapies, and (iii) diffuse foot process effacement on electron microscopy in the native kidney biopsy. All patients underwent genetic testing using next-generation sequencing. RESULTS: Twenty-four patients from 23 families were analyzed in this study. Pathogenic or likely pathogenic variants in FSGS/SRNS-related genes were identified in four of four families, zero of eight families, and 10 of 11 families with familial/syndromic, presumed primary, and undetermined FSGS/SRNS, respectively. Post-transplant recurrence only occurred in patients with presumed primary FSGS/SRNS. CONCLUSIONS: Our systematic approach based on precise clinicopathological findings including nephrotic syndrome, treatment responses, and diffuse foot process effacement might be useful to differentiate pediatric kidney transplant recipients with FSGS/SRNS who are likely to have a monogenic cause from patients who are not, and to predict post-transplant recurrence. A higher resolution version of the Graphical abstract is available as Supplementary information.

Identification of clinical factors related to antibody-mediated immune response to the subfornical organ.

OBJECTIVE: We recently reported cases of adipsic hypernatremia caused by autoantibodies against the subfornical organ in patients with hypothalamic-pituitary lesions. This study aimed to clarify the clinical features of newly identified patients with adipsic hypernatremia whose sera displayed immunoreactivity to the mouse subfornical organ. DESIGN: Observational cohort study of patients diagnosed with adipsic hypernatremia in Japan, United States, and Europe. METHODS: The study included 22 patients with adipsic hypernatremia but without overt structural changes in the hypothalamic-pituitary region and congenital disease. Antibody response to the mouse subfornical organ was determined using immunohistochemistry. The clinical characteristics were compared between the patients with positive and negative antibody responses. RESULTS: Antibody response to the mouse subfornical organ was detected in the sera of 16 patients (72.7%, female/male ratio, 1:1, 12 pediatric and 4 adult patients). The prolactin levels at the time of diagnosis were significantly higher in patients with positive subfornical organ (SFO) immunoreactivity than in those with negative SFO immunoreactivity (58.9 ± 33.5 vs. 22.9 ± 13.9 ng/ml, p < .05). Hypothalamic disorders were found in 37.5% of the patients with positive SFO immunoreactivity. Moreover, six patients were diagnosed with rapid-onset obesity with hypothalamic dysfunction, hypoventilation, and autonomic dysregulation/neural tumor syndrome after the diagnosis of adipsic hypernatremia. Plasma renin activity levels were significantly higher in patients with serum immunoreactivity to the Nax channel. CONCLUSIONS: The patients with serum immunoreactivity to the SFO had higher prolactin levels and hypothalamic disorders compared to those without the immunoreactivity. The clinical characteristics of patients with serum immunoreactivity to the subfornical organ included higher prolactin levels and hypothalamic disorders, which were frequently associated with central hypothyroidism and the presence of retroperitoneal tumors.

Amount and selectivity of proteinuria may predict the treatment response in post-transplant recurrence of focal segmental glomerulosclerosis: a single-center retrospective study.

BACKGROUND: Primary focal segmental glomerulosclerosis (FSGS) frequently recurs after kidney transplantation and is associated with poor graft survival. To date, few studies have investigated predictive factors for treatment responses in recurrent FSGS. METHODS: We retrospectively analyzed 16 patients who were < 16 years at the age of onset and had post-transplant recurrence of FSGS from 1993 to 2018. Patients who achieved complete remission or partial remission after initiating therapy for recurrent FSGS were defined as responders. We compared several clinical characteristics between responders and non-responders. Time to remission was also analyzed. RESULTS: Ten patients were responders, and six patients were non-responders. Univariate analysis showed that responders had a significantly lower amount of maximum proteinuria at the time of recurrence (P = 0.015) and more highly selective proteinuria (P = 0.013) than non-responders. The time to remission from initiation of therapy was 2 months (interquartile range 0.2-4.4). In all responders, except for one patient, remission was achieved within 6 months. CONCLUSIONS: Therapeutic responses may be predicted by examining the amount and selectivity of proteinuria at the time of recurrence. Further studies with larger numbers of patients are clearly required to validate these findings.

Valganciclovir prophylaxis for cytomegalovirus infection in pediatric kidney transplant recipients: a single-center experience.

BACKGROUND: There are two approaches for treating cytomegalovirus (CMV) infection occurring after kidney transplantation (KTx). One is preemptive therapy in which treatment is started after confirming positive CMV antigenemia using periodic antigenemia assay. The other approach is prophylactic therapy in which oral valganciclovir (VGCV) is started within 10 days after KTx and continued for 200 days. The Transplantation Society guidelines recommend prophylactic therapy for high-risk (donor's CMV-IgG antibody positive and recipient's negative) pediatric recipients. However, the adequate dose and side effects of VGCV are not clear in children, and there is no sufficient information about prophylaxis for Japanese pediatric recipients. METHODS: A single-center retrospective analysis was conducted on case series of high-risk pediatric patients who underwent KTx and received oral VGCV prophylaxis at the Department of Pediatric Nephrology, Tokyo Women's Medical University, between August 2018 and March 2019. Data were collected using medical records. RESULTS: The dose of administration was 450 mg in all the study patients (n = 5). Reduction or discontinuation was required in four of five patients due to adverse events, which included neutropenia in one patient, anemia in two patients, and neutropenia and digestive symptoms in one patient. Late-onset CMV disease occurred in all patients. No seroconversion was observed during prophylaxis. CONCLUSIONS: Our preliminary study suggests that the dosage endorsed by The Transplantation Society may be an overdose for Japanese pediatric recipients. Further studies are required to examine the safety and efficacy of VGCV prophylaxis in Japanese pediatric recipients.

A novel de novo truncating TRIM8 variant associated with childhood-onset focal segmental glomerulosclerosis without epileptic encephalopathy: a case report.

BACKGROUND: Heterozygous truncating variants in the Tripartite motif containing 8 (TRIM8) gene have been reported to cause epileptic encephalopathy, both with and without proteinuria. A recent study showed a lack of TRIM8 protein expression, with suppressor of cytokine signaling 1 (SOCS1) overexpression, in podocytes and tubules from a patient with a TRIM8 variant, who presented with epileptic encephalopathy and focal segmental glomerulosclerosis (FSGS). To date, no patients with TRIM8 variants who presented with nephrotic syndrome but without neurological manifestations have been described. CASE PRESENTATION: An 8-year-old girl presented with nephrotic syndrome, without epilepsy or developmental delay. Her kidney biopsy specimens showed FSGS and cystic dilatations of the distal tubules. Whole-exome sequencing identified a novel de novo heterozygous variant in the C-terminal encoding portion of TRIM8 (c.1461C > A), resulting in a premature stop codon (p.Tyr487*). Reverse transcription-polymerase chain reaction using peripheral blood mononuclear cells identified the mRNA sequence of the mutant allele, which confirmed an escape from nonsense-mediated mRNA decay. Immunofluorescence studies showed a lack of TRIM8 expression in glomerular and tubular cells and cystic dilatation of distal tubules. Immunohistochemical studies showed overexpression of SOCS1 in glomerular and tubular cells. CONCLUSIONS: We reported a patient with FSGS, associated with a de novo heterozygous TRIM8 variant, without any neurological manifestations. Our results expanded the clinical phenotypic spectrum of TRIM8 variants.

Clinical characteristics of Campylobacter enteritis after pediatric renal transplantation: A retrospective analysis from single center.

BACKGROUND: There are few reports of patients with Campylobacter enteritis after renal transplantation, and only a few case reports of bacteremia have been published. Although antibiotic therapy for 3-5 days has been recommended for immunocompromised patients, the optimal treatment for Campylobacter enteritis after renal transplantation has not been established. This study aimed to clarify the clinical characteristics and treatment outcomes of Campylobacter enteritis after pediatric renal transplantation. METHODS: This retrospective study included patients who underwent pediatric renal transplantation and were found to have Campylobacter species in stool cultures between January 2014 and May 2017. RESULTS: This study included eight patients who underwent pediatric renal transplantation. The median age at the time of renal transplantation was 14 years, and the median period between transplantation and disease occurrence was 4.6 years. Clinical symptoms were abdominal pain for eight patients, diarrhea for eight patients, fever for seven patients, vomiting for three patients, and headache for three patients. Campylobacter jejuni was isolated from the stool cultures of all patients. The median administration period of antibiotics as initial therapy was 7 days (range, 4-11 days). However, clinical relapse was observed in four patients after completing antibiotic therapy. Patients who experienced clinical relapse required a second course of antibiotic therapy for a median duration of 7 days (range, 5-10 days). CONCLUSIONS: Patients with Campylobacter enteritis after pediatric renal transplantation are at high risk for clinical relapse and may require a longer duration of antibiotic therapy than that generally described.

Risk factors for hyponatremia after hypotonic fluid infusion.

BACKGROUND: Hypotonic maintenance i.v. fluids (IVF) pose a higher risk of hyponatremia than isotonic maintenance IVF, but isotonic maintenance IVF can result in excess sodium (Na) load in children. This study analyzed the incidence and risk factors for hyponatremia in children given hypotonic fluids with different Na concentrations and different maintenance rates. METHODS: We performed a retrospective analysis using medical charts of children aged 3 months-15 years. The children were normonatremic (Na ≥135 mmol/L and <145 mmol/L) before IVF, and given IVF containing 35 mmol/L Na at a 100% maintenance rate (Na 35) or fluids containing 84 mmol/L Na at a 70% maintenance rate (Na 84) for 24-48 h. RESULTS: Of a total of 463 children, hyponatremia (Na <135 mmol/L) occurred in 46/275 children (17%) given Na 35, and 16/188 (9%) given Na 84 (P = 0.01). On multivariate logistic regression analysis, Na 35 (OR, 2.19; 95%CI: 1.04-4.62), low clinical dehydration scale (CDS) score before IVF (OR, 0.17; 95%CI: 0.06-0.49), and high body temperature 24-48 h after maintenance IVF (OR, 2.39; 95%CI: 1.79-3.18) were independent risk factors for hyponatremia. CONCLUSIONS: Maintenance IVF with low Na concentration at a 100% maintenance rate, low CDS before IVF, and a high body temperature 24-48 h after maintenance IVF are independent risk factors for hyponatremia.

MYH9-related disease with a normal platelet count.

MYH9-related disease (MYH9-RD) is characterized by congenital macrothrombocytopenia, progressive kidney failure, and sensorineural hearing loss. We describe a patient with MYH9-RD and a normal platelet count. A 13-year-old boy with a normal platelet count presented with proteinuria and hematuria and underwent a kidney biopsy. Light microscopy showed mild mesangial matrix expansion. Electron microscopy showed thinning of the glomerular basement membrane and splitting of the lamina densa. A tentative diagnosis of Alport syndrome was made. Unexpectedly, genetic analysis revealed a de novo MYH9 gene variant (p.Gln1068_Leu1074dup). A peripheral blood smear examination showed giant platelets and leukocyte inclusion bodies, confirming a diagnosis of MYH9-RD. In summary, we described a patient with MYH9-RD without thrombocytopenia who showed glomerular basement membrane abnormalities similar to Alport syndrome. Peripheral blood smear examinations may be helpful for an appropriate diagnosis of MYH9-RD, even in patients with proteinuria and a normal platelet count.

En bloc kidney transplantation from pediatric donors to teenage recipients: Two case reports.

Introduction: Since the implementation of the new selection criteria in 2018, kidney donations from pediatric patients have been prioritized for pediatric recipients and kidney donations from pediatric donors have increased in Japan. Herein, we present two cases of en bloc kidney transplantation. Case presentation: Case 1: A 19-year-old male patient who had been on hemodialysis for 5 years due to end-stage renal disease. After brain death, a graft from a 5-year-old boy was transplanted into the right iliac fossa. Case 2: A 19-year-old male patient, who had previously undergone a living kidney transplantation at the age of 3, received a secondary cadaveric kidney transplantation in the left iliac fossa. The graft was procured from a 17-month-old girl following cardiac death. Conclusion: This report will help surgeons perform en bloc kidney transplantation in the growing number of pediatric kidney donations, such as those in Japan.

Successful administration of eltrombopag in preparation for peritoneal dialysis catheter placement in a girl with MYH9-related disease.

MYH9-related disease is an autosomal dominant disorder characterized by macrothrombocytopenia, nephropathy, inclusion bodies in leukocytes, sensorineural hearing loss, and cataract. Severe cases require kidney replacement therapy in the patient's second decade of life; thrombocytopenia constitutes a major risk factor for hemorrhagic complications during dialysis initiation or kidney transplantation. Prophylactic platelet transfusion prior to surgery is commonly administered to affected patients in these cases. However, transfusion in such patients has limitations other than the general risk of allergic reactions and blood-borne infections; it may also trigger alloimmunization, leading to platelet transfusion resistance or the development of anti-donor antibodies in potential kidney transplant recipients. Here, we describe prophylactic administration of eltrombopag, an oral thrombopoietin receptor agonist, prior to laparoscopic peritoneal dialysis catheter placement in a 15-year-old girl with MYH9-related disease. Her platelet count was approximately 30 × 103/µL at baseline; it increased to 61 × 103/µL on the day before surgery, thereby avoiding the need for platelet transfusions. There were no major bleeding or adverse events associated with eltrombopag administration. Thus, eltrombopag may be a safe and effective alternative to prophylactic platelet transfusions in patients with MYH9-related disease.

Hinokitiol-induced decreases of tyrosinase and microphthalmia-associated transcription factor are mediated by the endoplasmic reticulum-associated degradation pathway in human melanoma cells.

Tyrosinase (TYR) is a key enzyme for melanin production. We previously showed that hinokitiol, a naturally occurring seven-membered ring terpenoid, potently inhibits human TYR activity. Interestingly, hinokitiol was recently reported to decrease expression of TYR and microphthalmia-associated transcription factor (MITF), which is a main transcription factor of the TYR gene, in murine melanoma cells. However, the mechanisms by which hinokitiol decreases the intracellular levels of TYR and MITF have not been fully elucidated. Here, we investigated the underlying mechanisms of the decreases using cultured human melanoma cells. As a result, hinokitiol treatment decreased TYR protein level in a time- and dose-dependent manner in G361 human melanoma cells, while MITF protein level was decreased only at higher concentrations after 3 days treatment. Notably, the mRNA levels of TYR and MITF were slightly increased by hinokitiol treatment. Therefore, we focused on the degradation of TYR and MITF in endoplasmic reticulum (ER)-associated protein degradation (ERAD) pathway. Importantly, co-treatment of ERAD inhibitor with hinokitiol restored the protein levels of TYR and MITF to approximately 30% and 20% of total those in untreated control cells, respectively. Hinokitiol affected the ER homeostasis as well as degradation of TYR and MITF in two human melanoma cell lines, G361 and HT-144, but the changes of ER-stress markers under the hinokitiol treatment were different in the two human melanoma cell lines. Taken together, these observations indicate that hinokitiol may induce ER stress and trigger the degradation of unfolded newly synthesizing TYR and MITF via the ERAD pathway.