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A first-in-human study of quantitative ultrasound to assess transplant kidney fibrosis
Kidney transplantation is the optimal treatment for renal failure. In the United States, a biopsy at the time of organ procurement is often used to assess kidney quality to decide whether it should be used for transplant. This assessment is focused on renal fibrotic burden, because fibrosis is an important measure of irreversible kidney injury. Unfortunately, biopsy at the time of transplant is plagued by problems, including bleeding risk, inaccuracies introduced by sampling bias and rapid sample preparation, and the need for round-the-clock pathology expertise. We developed a quantitative algorithm, called renal H-scan, that can be added to standard ultrasound workflows to quickly and noninvasively measure renal fibrotic burden in preclinical animal models and human transplant kidneys. Furthermore, we provide evidence that biopsy-based fibrosis estimates, because of their highly localized nature, are inaccurate measures of whole-kidney fibrotic burden and do not associate with kidney function post-transplant. In contrast, we show that whole-kidney H-scan fibrosis estimates associate closely with post-transplant renal function. Taken together, our data suggest that the addition of H-scan to standard ultrasound workflows could provide a safe, rapid and easy-to-perform method for accurate quantification of transplant kidney fibrotic burden, and thus better prediction of post-transplant renal outcomes.
Translocation-specific polymerase chain reaction in preimplantation genetic testing for recurrent translocation carrier
It is occasionally necessary to distinguish balanced reciprocal translocations from normal diploidy since balanced carriers can have reproductive problems or manifest other disease phenotypes. It is challenging to do this however using next generation sequencing (NGS) or microarray-based preimplantation genetic testing (PGT). In this study, discarded embryos were harvested from balanced reciprocal translocation carriers intending PGT that were determined to be unsuitable for transfer due to unbalanced translocations or translocation-unrelated aneuploidy. Two trophoectoderm biopsy samples were obtained from each single embryo. Whole genome amplification (WGA) was performed either by looping-based amplification (LBA) or multiple displacement amplification (MDA). NGS-based copy number variation (CNV) analysis as well as translocation-specific PCR was performed for each. We used embryo samples from t(8;22)(q24.13;q11.2) and t(11;22)(q23;q11.2) carriers since they are recurrent constitutional translocations that have nearly identical breakpoints even among independent unrelated families. CNV analysis was generally consistent between the two WGA methods. Translocation-specific PCR allowed us to detect each derivative chromosome in the MDA WGA samples but not with the LBA method, presumably due to coverage bias or the shorter sized WGA products. We successfully distinguished balanced reciprocal translocations from normal diploidy in normal samples with CNV analysis. A combination of CNV analysis and translocation-specific PCR using MDA-amplified WGA product can distinguish between balanced reciprocal translocation and normal diploidy in preimplantation genetic testing for structural rearrangements (PGT-SR).
Neddylation of RhoA impairs its protein degradation and promotes renal interstitial fibrosis progression in diabetic nephropathy
Diabetic nephropathy (DN) is a common and serious complication of diabetes, characterized by chronic fibro-inflammatory processes with an unclear pathogenesis. Renal fibrosis plays a significant role in the development and progression of DN. While recent research suggests that the neddylation pathway may influence fibrotic processes, its specific dysregulation in DN and the underlying mechanisms remain largely unexplored. This study identified the neddylation of RhoA as a novel post-translational modification that regulates its expression and promotes renal fibrosis in DN. We here demonstrated that two key components of the neddylation pathway—NEDD8-activating enzyme E1 subunit 1 (NAE1) and NEDD8—are significantly upregulated in human chronic kidney disease (CKD) specimens compared to healthy kidneys, implicating neddylation in CKD-associated fibrosis. Our findings further revealed that both pharmacological inhibition of neddylation using MLN4924 and genetic knockdown of NAE1 mitigate renal fibrosis in mouse models of streptozotocin-induced diabetes and unilateral ureteral obstruction (UUO). Immunoprecipitation-mass spectrometry (IP-MS) and subsequent function assays demonstrated a direct interaction between RhoA and NEDD8. Importantly, neddylation inhibition reduced RhoA protein expression, highlighting a potential therapeutic target. Additionally, a positive correlation was noted between elevated NEDD8 mRNA levels and RhoA mRNA expression in human CKD specimens. RhoA overexpression counteracted the antifibrotic effects of neddylation inhibition, underscoring its critical role in fibrosis progression. Mechanistically, we unveiled that neddylation enhances RhoA protein stability by inhibiting its ubiquitination-mediated degradation, which subsequently activates the ERK1/2 pathway. Collectively, this study provides novel insights into NAE1-dependent RhoA neddylation as a key contributor to renal fibrosis in DN.
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