Molecular Changes Associated with Type IV Collagen Switching in 1-Day-Old Alport Murine Glomeruli
Bibliographic record
Abstract
Background: Alport syndrome (AS) is an inherited disorder caused by pathogenic variants in COL4A3, COL4A4 or COL4A5, which encodes proteins that comprise basement membranes of the ear, eye and kidney glomerulus. Type IV collagen chains assemble as heterotrimers and during glomerular development, α1α2α1 (IV) is replaced by α3α4α5 (IV) within the developing glomerular basement membrane (GBM). This “switching” defines the starting point of disease in AS. We aimed to identify the molecular changes at the time of disease initiation in the developing glomeruli of Alport murine kidneys. Methods: Immunofluorescence (IF) staining was done to identify the GBM distribution of type IV collagen chains in 1 day old COL4A3 knockout (KO) and wildtype (WT) mice. Urine albumin to creatinine ratio (uACR) was also measured. Subsequently, glomeruli from 1 day old (P1) COL4A3 KO and WT mice were isolated by cardiac injection of magnetic dynabeads that embolized to glomerular capillaries enabling their extraction from surrounding tissue. Protein was isolated and subjected to liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS) analysis. Results: IF localized type IV collagen α1 in the GBM, Bowman's capsule and mesangial matrix in both P1 KO and WT mice. Type IV collagen α5 was present in short segments of some developing GBM in P1 WT but was absent in KO mice indicating switching. uACR was increased in P1 KO (423.61±396.13 mg/mmol) compared to WT (128.67±69.86 mg/mmol) with a p-value of 0.02. LC-MS/MS identified >4300 proteins from glomerular isolates. In males, 2 and 15 proteins were significantly upregulated and downregulated, respectively, in KO compared to WT mice. In females, 543 and 978 proteins were significantly upregulated and downregulated, respectively, in KO compared to WT mice. Pathway analysis revealed alteration in collagen metabolic process, collagen biosynthesis, collagen formation and extracellular matrix organization. Conclusions: Increased uACR in P1 KO mice showed disease onset at the time of type IV collagen switching. LC-MS/MS analysis revealed dysregulation of matrix turnover pathways in P1 KO mice, identifying potential molecular targets. Funding: Private Foundation Support
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".