CUL3 primary-source assay notes

These notes make three source-specific judgments locally checkable without replacing the publication caches. The original PDF text and the identified figure captions were inspected. Figure pixels and separate supplements were not newly inspected for this follow-up. The two 2025 letters appeared together in the retrieved PDF; they are opposing interpretations, not independent confirmations.

PMID:25250572 — adult renal deletion and expression measurements

Original JCI article, J Clin Invest. 2014;124:4723–4736; original PDF; PMC4347254.

• Design: printed p. 4724, final Introduction paragraph; p. 4728, the Results paragraph introducing kidney-specific deletion; pp. 4734–4735, Animals and dietary Methods. The experiment deletes Cul3 along the nephron after normal development using doxycycline-controlled Pax8/TRE-LC1 recombination. The stated restriction is “only in adult mice”. The short-term dietary experiment uses mice aged 2–3 months. It tests adult maintenance and physiology, rather than embryonic kidney morphogenesis.
• Inflammation: printed p. 4730, Results describing chronic kidney damage; p. 4734, Figure 8 caption. Histology identifies tubulointerstitial inflammation, fibrosis, neutrophils and white-cell casts following deletion. This establishes an injury-associated inflammatory outcome; it does not isolate a step of inflammatory response performed by CUL3.
• Expression: printed pp. 4727–4728, Figure 4 caption and Results on nephron expression; p. 4735, nephron-segment PCR Methods. The authors quantify Klhl3 and Cul3 transcripts across isolated nephron segments, describing Cul3 as showing “modest and relatively uniform expression”. This is expression of the measured genes. The deletion Results use Western blotting/immunofluorescence to assess WNK kinases, transporters and phosphorylation, alongside electrolyte and physiological endpoints. The previous row 65 wording about altered renal transcript levels after deletion was too specific and is superseded. These measurements do not identify CUL3 itself as executing transcription, RNA processing or translation.

The kidney-development, inflammatory-response and gene-expression transfers remain source-specific over-annotations. This is not a general rejection of other CUL3 developmental or transcription-related biology. The stem-cell-division and embryonic-cleavage judgments cite a different paper, PMID:22358839, and must not be attributed to this renal experiment.

PMID:39780017 — challenge to KLHL22–DEPDC5 turnover

Original challenge, Nature 2025;637:E11–E14; PDF.

Printed p. E11 describes antibody validation using DEPDC5-knockout and endogenous 3×Flag-tagged HEK293T cells. The authors report that validated endogenous DEPDC5 signals do not change as proposed under amino-acid, proteasome-inhibition or KLHL22-loss conditions. Printed p. E12, Figure 1 caption and ensuing text, identifies the measured immunoblot and signaling endpoints. These are the challenge's reported findings, not a new analysis of its image pixels.

Printed p. E13, Cell lines and tissue culture plus Transfection and cell lysis Methods, distinguishes routine culture in DMEM from the starvation/refeeding protocol: “amino-acid-free RPMI for 50 min”, followed by amino-acid addition for 10 minutes. Printed p. E11, final main paragraph, expressly leaves broader ubiquitin regulation of mTORC1 possible while challenging the proposed acute DEPDC5-degradation mechanism. Its result should not be paraphrased as disproving every ubiquitin-dependent effect.

PMID:39780003 — reply and remaining uncertainty

Original reply, Nature 2025;637:E15–E17; PDF.

Printed p. E15 discusses antibody/cleavage interpretation and potential effects of endogenous epitope tagging. Printed pp. E15–E16, the nutrient-treatment paragraph and Figure 1i caption, contrast the reply's use of DMEM for culture and amino-acid treatments with the challenge's switch to RPMI. Printed p. E16, Figure 1j–l caption, describes the proposed ubiquitination/degradation evidence and model; printed p. E17, concluding paragraph, restricts that model to “a subset of DEPDC5”. These proposed reagent, tagging and condition explanations do not establish that either report is universally applicable.

Accordingly, PMID:29769719 remains DISPUTED, with both challenge and reply named. The specific amino-acid-response and TORC1-regulation assertions remain UNDECIDED. Broad CUL3 scaffold and proteasomal-turnover functions retain their independent experimental support; the contested DEPDC5 route is not used as their sole justification. No retraction or universal nonbinding/degradation conclusion is asserted.