Although the COVID-19 pandemic is now considered over, the virus remains prevalent, and regular, on-time vaccination is recommended. Traditional and RNA-based vaccines have proven lifesaving for millions worldwide; however, their long-term efficacy remains unknown. The unmet need is to identify interventions that mitigate the severity of SARS-CoV-2 infection and associated health complications, including damage to multiple organs. Pro-inflammatory cytokines, including tumor necrosis factor (TNF), play a crucial role in the pathogenesis of COVID-19 and the progression to multiple organ failure. The present study describes the role of Mixed Lineage Kinase 3 (MLK3), a TNF downstream target and mitogen-activated protein kinase upstream regulator, in SARS-CoV-2-induced kidney injury. MLK3 activity was higher in SARS-CoV-2-infected K18-hACE2 mice and in human kidneys, and it positively correlated with kidney injury. MLK3 transcriptionally upregulated TMPRSS2 expression via the NFATc1, and genetic or pharmacological inhibition of MLK3 mitigated SARS-CoV-2 pseudovirus entry into kidney cells. SARS-CoV-2 spike glycoprotein receptor binding domain (Spike-RBD) activated MLK3, thereby regulating IL-17A. Heat shock protein 70 (Hsp70) interacts with MLK3 and regulates Spike-RBD-induced IL-17A production and ultimately apoptosis in kidney cells. Our results suggest that MLK3 inhibitors could serve as a therapeutic intervention in COVID-19 patients with acute kidney injury.

Background Diagnostic interpretation of kidney allograft biopsies using the Banff classification remains variable, but the determinants of this variability are not fully defined. We performed a global, fully digital multi-reader study to identify the principal drivers of disagreement in Banff-based assessment. Methods Thirty six kidney transplant biopsies were independently scored by 67 renal pathologists on a standardized digital platform. Readers assessed Banff lesions on hematoxylin and eosin, periodic acid Schiff, and Jones' silver stains; final diagnostic categories were assigned using prespecified Banff-based decision rules. Interobserver agreement was quantified with Gwet's agreement coefficient (AC) statistics. Determinants of diagnostic agreement were evaluated) using pairwise mixed-effects logistic regression, and reader similarity was examined by principal component analysis (PCA) with post hoc molecular annotation. Results Agreement for final diagnostic categories was moderate (Gwet's AC1, 0.55; 95% CI, 0.47 - 0.63). Lesion-level agreement varied substantially, with lowest agreement for selected threshold-dependent inflammatory or semi-quantitative lesions, including interstitial inflammation in areas of IFTA, peritubular capillaritis and arteriolar hyalinosis. Diagnostic concordance differed markedly across biopsies, indicating strong case-level heterogeneity. In pairwise models, differences in active inflammatory and vascular lesion scoring were the strongest correlates of diagnostic disagreement; reader experience and geography contributed minimally. Principal component analysis showed reader variation was organized along two dominant axes: a rejection-calling threshold axis linked mainly to tubulointerstitial inflammatory injury, and a T cell-mediated (TCMR/TI) and antibody-mediated/microvascular (AMR/MVI) inflammation-oriented phenotypic classification axis. Conclusion Interobserver variation in Banff-based kidney transplant biopsy assessment is structured rather than random and driven mainly by how readers threshold and integrate key inflammatory lesion compartments rather than experience or geographic location.

BACKGROUND Acute interstitial nephritis (AIN) is a common cause of acute kidney injury (AKI), but the diagnosis may be missed as kidney biopsies are rarely obtained when acute tubular injury (ATI) is suspected.METHODS The Kidney Precision Medicine Project is a cohort study that obtains kidney biopsies from individuals with AKI, which undergo pathologic and molecular interrogation. We compared ATI and AIN cases among the first 60 AKI participants.RESULTS On clinicopathologic adjudication, 30 patients (50%) had a primary adjudicated diagnosis of ATI, 13 (22%) patients had AIN, 9 (15%) had diabetic nephropathy, and 3 (5%) had other conditions. There were increased interstitial white blood cells and tubulitis (P < 0.05 for both) in AIN compared with ATI. Prior to biopsy, the treating clinician suspected ATI in 83% of the cases with adjudicated ATI, while the treating clinician suspected AIN in 54% of the cases with AIN. Tissue transcriptomic signatures showed enrichment of proinflammatory signaling and increased expression of CXCL9, a chemokine induced by IFN-γ, in myeloid cells of participants with AIN. CXCL9 localized to inflammatory infiltration in spatial transcriptomic data.CONCLUSION Adjudication of kidney biopsies revealed distinct pathologic and molecular profiles between ATI and AIN. Kidney biopsy should be considered more frequently in AKI, as AIN is clinically underrecognized.TRIAL REGISTRATION ClinicalTrials.gov NCT04334707.FUNDING National Institute of Diabetes and Digestive and Kidney Diseases grants U01DK133081, U01DK133091, U01DK133092, U01DK133093, U01DK133095, U01DK133097, U01DK114866, U01DK114908, U01DK133090, U01DK133113, U01DK133766, U01DK133768, U01DK114907, U01DK114920, U01DK114923, U01DK114933, U24DK114886, UH3DK114926, UH3DK114861, UH3DK114915, and UH3DK114937.

Anaplastic thyroid cancer (ATC) is an aggressive malignancy with a poor prognosis and limited treatment options. Previous studies have shown that selective downregulation of the MADD (MAP-kinase-activating death domain-containing protein) gene isoform increases ATC cell susceptibility to TRAIL-induced apoptosis. However, the existence of multiple MADD gene isoforms raised the possibility of functional compensation. This study aimed to definitively evaluate the role of MADD in ATC by employing CRISPR-Cas9 to Cas9 to target exon 3, a conserved exon expressed in all known MADD isoforms, resulting in functional knockout of MADD expression. CRISPR-Cas9-mediated MADD knockout, performed in three ATC cell lines (8505 C, C643, and HTH7) with distinct mutational backgrounds, significantly impaired ATC cell function in vitro, as indicated by reduced viability, increased apoptosis, decreased migration, and G0/G1 cell cycle arrest. RNA-seq analysis revealed alterations in genes related to cell survival, proliferation, and metastasis. In the orthotopic ATC mouse model, MADD deletion dramatically suppressed tumor growth, reduced lung metastases, and prolonged survival. Our findings demonstrate that MADD plays a crucial role in ATC cell survival, proliferation, and metastasis. The consistent effects observed across multiple cell lines and in vivo models suggest that MADD may represent a promising therapeutic target for this aggressive malignancy.

Building upon a foundational Human Kidney resource, we present a comprehensive multi-modal atlas that defines spatially resolved versus unresolved repair states and mechanisms in human kidney disease. Homeostatic interactions between injured kidney epithelium and its surrounding milieu determine successful repair outcomes, while pathogenic signaling promotes unresolved inflammation and fibrosis leading to chronic disease. We integrated multiple single-cell and spatial modalities across ~700 samples from >350 patients (~250 research biopsies), analyzing ~1.7 million cells alongside complementary mouse multi-omic profiles spanning acute-to-chronic injury and aging (>300,000 cells) and spatial transcriptomic analysis of >150 human biopsies. This cross-species atlas delineates functional pathways and druggable targets across the nephron and defines gene regulatory networks and chromatin landscapes governing tubular, fibroblast, and immune cell transitions from injury to either recovery or failed repair states. We identified distinct cellular states associated with specific pathological features that show dynamic distributions between acute kidney injury (AKI) and chronic kidney disease (CKD), organized within unique spatial niches that reveal progression mechanisms from early injury to unresolved disease. Gene regulatory analyses prioritized key transcription factor activities (SOX4, SOX9, NFKB1, REL, KLFs) and their target networks establishing disease states and tissue microenvironments. These regulatory programs were directly linked to clinical outcomes, identifying molecular signatures of recovery and secreted biomarkers predictive of AKI-to-CKD progression, providing a key resource for therapeutic development and precision medicine approaches in kidney disease.

In sickle cell disease (SCD), progressive renal dysfunction is common and driven by mechanisms such as chronic hemolysis, vascular damage, and ischemia. Studies suggest that Losartan, an FDA-approved antihypertensive targeting the renin-angiotensin-aldosterone system (RAAS), may offer renoprotective benefits in SCD. Osivelotor (GBT021601), a second-generation inhibitor of sickle hemoglobin (Hb) polymerization, shares a mechanism with voxelotor, but has improved pharmacokinetics. By reducing hemolysis and circulating cell-free Hb, Osivelotor may decrease Hb-induced renal toxicity.We hypothesized that combined treatment with Osivelotor and Losartan, would improve kidney function and histopathology in SCD mice. Transgenic sickle mice (Hb SS; Townes model, Jackson Laboratory) were treated starting at 12 weeks of age for 14 weeks with either control chow (C), Osivelotor (O), Losartan (L), or Osivelotor + Losartan (O+L). Osivelotor (300mg/kg/day) was milled in standard rodent diet and Losartan (0.2mg/mL) was dissolved in drinking water. Each group included 12 mice (6 males, 6 females). Blood, urine and kidney tissues were collected at 26 weeks. We assessed markers of hemolysis (Hb, reticulocyte %, hemoglobinuria), reactive oxygen species (thiobarbituric acid reactive substances [TBARS]), kidney injury (kidney injury molecule-1 [KIM-1], nephrin), and kidney function (albuminuria, serum cystatin C and creatinine). Serum erythropoietin was normalized to hematocrit (HCT). Histopathology was assessed using picrosirius red staining. Group comparisons were analyzed by ANOVA adjusted for sex. Data are shown as mean ± standard error.SCD mice treated with Osivelotor had significantly higher Hb concentrations (O: 12.2±0.4 g/dL, O+L: 8.5±0.5g/dL) compared to control (C: 6.8±0.3g/dL) or Losartan-only (L: 4.8±0.3g/dL) treated SCD mice (P<0.001). Hemolytic biomarkers, including absolute reticulocyte count (C: 3599±110, O: 2372±147, L: 3139±158, O+L: 2377±171 x103/µL; P<0.001) and urine cell-free Hb concentrations (C: 9.1±1.1, O: 3.2±0.8, L: 6.8±1.5, O+L: 5.4±1.7 ng/24h; P=0.02), improved with Osivelotor treatment. Serum erythropoietin-to-HCT concentration, a surrogate biomarker of hypoxia sensed by peritubular cells in the kidney cortex, improved with Osivelotor treatment (C: 3204±485, O: 1700±172, L: 9408±3250, O+L: 2804±462 pg/mL/HCT; P=0.001). Hemolytic biomarkers were not improved with Losartan alone.Biomarkers of oxidative stress (TBARS; C: 86.4±6.6, O: 69.8±5.5, L: 43.2±3.2, O+L: 33.9±3.6 nmol/24h; P<0.001), glomerular injury (nephrin; C: 9.4±0.3, O: 8.2±0.3, L: 1.1±0.1, O+L: 0.9±0.07 ng/24h; P<0.001 ), and tubular injury (KIM-1; C: 606±125, O: 564±107, L: 424±108, O+L 271±58 pg/24h; P=0.0033) progressively improved with Osivelotor, Losartan, and the combination of Osivelotor+Losartan treatment, respectively.Kidney function demonstrated a progressive reduction in albuminuria with treatment (C: 120±16, O: 101±8, L: 31±5, O+L: 20±4 µg/24h; P<0.001). We did not observe substantial changes in serum concentrations of cystatin C (C: 0.49±0.03, O: 0.46±0.02, L: 0.62±0.04, O+L: 0.54±0.04 µg/ml) or serum creatinine (C: 0.09±0.005, O: 0.09±0.006, L: 0.12±0.007, O+L: 0.13±0.013 mg/dL) with treatment, although both arms of treatment that included Losartan had mild elevations in these values.Histopathology demonstrated global and diffuse glomerular mesangial expansion and mild interstitial fibrosis in the control group. The Osivelotor+Losartan group exhibited reduced severity, with only focal and segmental mesangial expansion and minimal interstitial fibrosis while Osivelotor and Losartan-alone groups displayed intermediate features.In conclusion, this study demonstrates that targeting both hemolysis and RAAS provides additive renoprotective effects in SCD. Osivelotor, a potent inhibitor of Hb S polymerization, moderated hemolysis leading to reduced circulating cell-free Hb and oxidative stress, two key drivers of tubular injury in SCD. Losartan, an angiotensin II receptor blocker, mitigates RAAS-mediated pathways involved in glomerular hypertension, mesangial expansion, and interstitial fibrosis. The combination treatment led to the greatest improvement across functional, molecular and structural indicators of kidney damage. These findings suggest that co-targeting hemolytic and RAAS pathways addresses the multifactorial nature of SCD nephropathy, offering a potentially synergistic therapeutic strategy.

Kidney and renal pelvic cancer are a significant cause of cancer-related deaths, with the most common malignant kidney tumor being renal cell carcinoma (RCC). Chromophobe renal cell carcinoma is a rarer form of RCC that poses significant challenges to accurate diagnosis, as it shares many histologic features with Oncocytoma, a benign renal tumor. Biopsies for histopathological and immunohistochemical analysis have limitations in distinguishing chromophobe RCC from Oncocytoma. Syndromic cases may also have tumors with overlapping features. Techniques such as infrared (IR) spectroscopic imaging have shown promise as an alternative approach to tissue diagnostics. In this study, we propose a deep-learning-based framework for automating classification in kidney tumor tissue microarrays (TMAs) using an IR dataset. Feature selection algorithms reduce data dimensionality, followed by a deep learning classification approach. A classification accuracy of 91.3% was observed for validation data, even with the use of 13.6% of all wavelengths, thereby reducing training time by 21% compared to using the entire spectrum. Through the integration of scalable deep learning models coupled with feature selection, we have developed a classification pipeline with high predictive power, which could be integrated into a high-throughput real-time IR imaging system. This would create an advanced diagnostic tool for the detection and classification of renal tumors, namely chromophobe RCC and Oncocytoma. This may impact patient outcomes and treatment strategies.

Vaso-occlusive episodes (VOEs) in the setting of hyperhemolysis can rapidly evolve into multiorgan failure in sickle cell disease (SCD). Although the mechanisms for rapid progression to multiorgan failure are unclear, a systemic vasculopathy with thrombotic microangiopathy-type features has been described. Reduced thrombomodulin (TM) function is implicated in some thrombotic microangiopathy syndromes. We observed a greater decline in platelet count and hemoglobin concentration and an increase in vascular injury biomarkers within 24 hours of admission for a VOE in 12 patients with SCD with multiorgan failure versus 12 patients without multiorgan failure. We observed decreased TM expression on the lung and kidney vasculature of 3 additional patients with SCD with multiorgan failure compared with a control patient without SCD. Transgenic SCD mice challenged with cell-free hemoglobin had reduced TM function, increased vascular injury biomarkers, and reduced renal cortical blood flow. Infusion of recombinant TM 2 or 24 hours after the challenge restored cortical blood flow and mitigated increases in vascular injury, complement activation, and tubular injury biomarkers, and protected against acute kidney and lung injury. We demonstrated that impaired TM function may be involved in the systemic vasculopathy of SCD-related multiorgan failure, and infusion of recombinant TM may restore vascular function and protect against acute organ damage.

We describe a patient with sickle cell disease (SCD) and elevated antiphospholipid antibodies (aPL) who developed multi-organ failure resembling catastrophic antiphospholipid syndrome. Autoimmune screening revealed several autoantibodies characteristic of systemic lupus erythematosus (SLE). Notably, routinely housed and unmanipulated transgenic sickle mice displayed significantly elevated titres of aPL- and SLE-associated autoantibodies. We hypothesize that SCD may be a risk factor not only for the development of aPL but also more widespread autoimmunity.

Chronic kidney disease (CKD) is a common complication that leads to substantial morbidity and early mortality in sickle cell anemia (SCA). Renin-angiotensin-aldosterone system (RAAS) inhibitors, such as losartan, are recommended to treat SCA-related CKD although these guidelines are based on small studies with short follow-up. The pathophysiology of SCA-related CKD is complex with increased hemolysis and hemoglobinuria identified as risk factors for the development and progression of CKD (PMID 24329963). GBT1118, a mouse analogue of voxelotor, reduces intravascular hemolysis and hemoglobinuria thereby protecting the kidneys from damage if started early (12 weeks of age) before CKD has developed in SCA mice (PMID 35759756). We investigated whether concurrent GBT1118 + losartan treatment would improve biomarkers of kidney damage and kidney function in older SCA mice starting at 24 weeks of age when CKD is evident. Transgenic sickle mice (Hb SS; Townes model, Jackson Laboratory) were treated as follows: A) GBT1118 + losartan, B) losartan-only, C) control chow (n = 10; 5 male and 5 female mice in each arm). Losartan treatment was started at 21 weeks (groups A & B), GBT1118 at 24 weeks (group A), and both treatments continued until 36 weeks of age. Urine was collected for 24 hours using metabolic cages. We compared markers of hemolysis (hemoglobin, reticulocyte %, hemoglobinuria), reactive oxygen species (thiobarbituric acid reactive substances [TBARS]), kidney injury (kidney injury molecule-1 [KIM-1], nephrin), and kidney function (albuminuria, proteinuria; serum cystatin C and BUN) using ANOVA adjusting for sex. Mean ± standard error values are provided. At 36 weeks of age, SCA mice treated with GBT1118 + losartan (Group A) had higher hemoglobin concentrations (A: 6.9 ± 0.3 g/dL, B: 5.2 ± 0.4 g/dL, C: 6.5 ± 0.1 g/dL; P = 0.0017), lower reticulocyte % (A: 23 ± 1%, B: 33 ± 1%, C: 38 ± 1%; P < 0.0001), and lower urine hemoglobin concentrations (A: 0.3 ± 0.1 ng/24h, B: 1.7 ± 0.2 ng/24h, C: 1.7 ± 0.3 ng/24h; P = 0.0001) compared to the losartan-only (Group B) and control (Group C) mice. The hemoglobin concentrations and reticulocyte % were significantly lower in the losartan-only versus control mice (P ≤ 0.002). Urinary biomarkers of oxidant injury (TBARS; A: 43.2 ± 4.5 nmol/24h, B: 80.9 ± 8.1 nmol/24h, C: 87.0 ± 5.9 nmol/24h; P = < 0.0001) and tubular injury (KIM-1; A: 163 ± 13 pg/24h, B: 219 ± 21 pg/24h, C: 307 ± 24 pg/24h; P = 0.0002) were lowest in SCA mice receiving GBT1118 + losartan. Urinary nephrin concentrations, a biomarker of glomerular injury, were similar in the GBT1118 + losartan and losartan-only treated mice and trended lower compared to control mice (A: 8.1 ± 0.9 ng/24h, B: 8.0 ± 1.1 ng/24h, C: 9.8 ± 0.9 ng/24h; P = 0.2). We observed significant improvements in albuminuria (A: 22 ± 2 µg/24h, B: 37 ± 6 µg/24h, C: 115 ± 15 µg/24h; P < 0.0001) and proteinuria (A: 1.0 ± 0.2 mg/24h, B: 1.5 ± 0.2 mg/24h, C: 4.2 ± 0.5 mg/24h; P < 0.0001) in the GBT1118 + losartan treated mice. Serum cystatin C and BUN increased in the losartan-only treated mice compared to control mice (P≤ 0.004) while remaining stable in the GBT1118 + losartan treated mice (cystatin C; A: 606 ± 15 ng/mL, B: 667 ± 19 ng/dL, C: 586 ± 14 ng/dL) (BUN; A: 26 ± 1 mg/dL, B: 32 ± 2 mg/dL, C: 24 ± 2 mg/dL). Studies are ongoing to evaluate histopathologic and ultrastructural kidney changes across the three treatment groups. In conclusion, the combination of GBT1118 + losartan improves hemolysis as well as several biomarkers of kidney injury and function in older SCA mice after CKD has developed. Losartan reduces intraglomerular pressure and we observed that losartan-only treated mice had lower urine nephrin, albumin and protein concentrations compared to control SCA mice. RAAS inhibitors have been shown to reduce erythropoietin levels and decrease kidney perfusion pressures in some studies of non-SCA related CKD. Consistent with this, losartan-only treated SCA mice developed more severe anemia and increased serum cystatin C and BUN concentrations compared to control SCA mice. Adding GBT1118 to losartan provided additional protection to the kidney, based upon further improvements in urine TBARS, KIM-1, albumin and protein concentrations, while improving the hemoglobin concentration and maintaining stable serum cystatin C and BUN levels. Our results provide support for developing multimodal strategies, such as the combination of voxelotor + losartan, to treat SCA-related CKD in humans.

Context.— End-stage kidney disease (ESKD) is defined as renal impairment requiring renal replacement therapy to sustain life. With a 1-year mortality of ∼20% to 30%, many die of complications related to this disease. Objective.— To determine the percentage of autopsy cases of decedents with ESKD in which the contribution of ESKD to death is accurately reflected in the final report. Design.— Autopsy case records were retrospectively reviewed at 4 institutions (Yale New Haven Hospital, University of Chicago Medical Center, University of Illinois at Chicago Hospital, University of Iowa Hospital). Clinical, macroscopic, and microscopic autopsy findings were reviewed, with attention to renal disease findings. Results.— One hundred sixty decedents with documented ESKD and premortem dialysis who underwent autopsy assessment were identified. ESKD was implicated as a cause of death (CoD) or significant contributing factor in 44 cases (28%), but not in the remaining 116 cases (72%). Cardiovascular disease was the most common CoD in ESKD. There was significant interpathologist variation in the inclusion of ESKD as a CoD across institutions. These rates ranged from 85% correlation (23 of 27 cases), to 13% (4 of 31 and 8 of 62 cases at 2 institutions), and 22.5% (9 of 40 cases) across the 4 participating institutions. Conclusions.— The recognition at autopsy of ESKD as a CoD or contributing CoD at autopsy in patients undergoing dialysis remains low (28%). The detrimental impact of ESKD is not reflected in hospital autopsy reports, which carries implications for collection of vital statistics and allocation of research funding for kidney diseases.

Allograft rejection is a significant cause of renal transplant failure which needs prompt diagnosis and treatment for graft salvage. Angiotensin II type 1 receptor antibody-mediated rejection (AT1R-AMR) is increasingly being identified as the etiology of antibody-mediated rejection in kidney transplant recipients with allograft rejection but without detectable human leukocyte antigen (HLA) antibodies. While some reports have suggested that AT1R-AMR may be refractory to standard therapy, others have reported improvement or stabilization of graft function. We present two patients in which anti-rejection therapy including therapeutic plasma exchange was unable to salvage the allograft.

The mechanisms by which severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) may spread to the human brain are poorly understood, and the infection of cancer cells in the brain by SARS-CoV-2 in Coronavirus disease 2019 (COVID-19) patients has been the subject of only one previous case report. Here, we report the detection of SARS-CoV-2 RNA by in situ hybridization in lung-cancer cells metastatic to the brain and adjacent brain parenchyma in a 63-year-old male patient with COVID-19. These findings suggest that metastatic tumors may transport the virus from other parts of the body to the brain or may break down the blood-brain barrier to allow for the virus to spread to the brain. These findings confirm and extend previous observations that cancer cells in the brain can become infected by SARS-CoV-2 in patients with COVID-19 and raise the possibility that SARS-CoV-2 can have a direct effect on cancer growth and outcome.

Rationale & Objective: Kidney transplant is a mainstay of kidney replacement therapy. Given a continued shortage of organs, pediatric en bloc kidney transplants may have substantial utility. We present our long-term experience with en bloc transplants from donors aged 3 to 60 months, including changes in kidney function and kidney volume over time as well as biopsy findings.Study Design: Case series.Setting & Participants: Medical records from a single academic medical center were reviewed. Aggregate serial volumes of 22 en bloc kidney al-lografts from 2010 to 2017 were assessed at the time of transplant and during follow-up. Estimated glomerular filtration rates (eGFR) were described at 3 months after transplant (baseline) as well as over the ensuing 3 years. Interstitial fibrosis, a finding determined by histopathologic review, which results from an accumulation of collagen that is produced from mediators produced from complex interaction of multiple inflammatory cells,was assessed on 20 protocol biopsies obtained from 6 patients, of which 4 patients had 4 biopsies and 2 patients had 1 biopsy.Results: Kidney volume was obtained from 51 ul-trasound studies performed up to 74 months after transplant. Kidney volume generally increased and eGFR rose over time after the transplant, with 23% patients achieving an eGFR of >75 mL/min/1.73 m2 at 3 months posttransplant. The remainder achieved an eGFR >75 mL/min/1.73 m2 over the ensuing 3 years. Interstitial fibrosis noted on bi-opsies appeared to foreshadow an eventual reduction in kidney volume. Limitations: Retrospective study, possible selec-tion bias, single-center experience.Conclusions: The kidney en bloc allografts increased in size after transplantation, with associ-ated improved kidney function. Chronic damage to the graft, from interstitial fibrosis and tubular atrophy, resulted in long-term reduction in kidney volume.

The ratio of mRNA not selected for polyadenylation (non-poly(A)+ selected) to mRNA selected for polyadenylation (poly(A)+) for the beta 1, alpha 1 and gamma 2 subunits of the GABAA receptor complex was examined in rats as a function of age. RNA was extracted from whole brain of rats that were either 0, 1, 3, 5 or over 60 days of postnatal age. Poly(A)+ mRNA was purified by oligo(dT)-cellulose chromatography. Non-poly(A)+ selected mRNA and poly(A)+ mRNA for the GABAA receptor beta 1, alpha 1 and gamma 2 subunits were examined by Northern blot analysis using cDNA probes specific for these subunits. Levels of GABAA receptor beta 1 subunit mRNA were also examined by solution hybridization analysis with a beta 1 riboprobe. Analysis of Northern blots revealed that levels of poly(A)+ beta 1 subunit mRNA were highest at 0 days of age, but decreased and reached adult levels by 5 days of postnatal age. However, levels of the beta 1 subunit message extracted from non-poly(A)+ selected mRNA were not significantly different at any of the ages examined, suggesting the existence of a population of beta 1 subunit mRNA that is not polyadenylated. The age-related discrepancy between beta 1 subunit levels measured in non-poly(A)+ selected mRNA and poly(A)+ mRNA was also observed using solution hybridization analysis. In contrast, levels of both non-poly(A)+ selected mRNA and poly(A)+ mRNA for the alpha 1 subunit of the GABAA complex increased from 0 days of age to adulthood. Similarly, levels of both non-poly(A)+ selected mRNA and poly(A)+ mRNA for the GABAA receptor gamma 2 subunit increased with age.(ABSTRACT TRUNCATED AT 250 WORDS)