Hypoxia‐Inducible Factor‐1α Is Constitutively Expressed in Murine Leydig Cells and Regulates 3β‐Hydroxysteroid Dehydrogenase Type 1 Promoter Activity
Bibliographic record
Abstract
Hypoxia-inducible factor-1alpha (HIF-1alpha) is a transcription factor that plays an essential role in oxygen homeostasis. HIF-1alpha is constitutively made in cells; however, it is ubiquitinated and degraded under normoxic conditions. Hypoxia prevents the ubiquitination of HIF-1alpha, resulting in stabilization of the protein and activation of target genes. Because of its vascular arrangement and the high metabolic demand of spermatogenesis, the testis has been described previously as functioning on the brink of hypoxia; thus, we have hypothesized that HIF-1alpha is constitutively expressed and stabilized in the testis, where it could play a role in testicular homeostasis. Western blot analysis using nuclear proteins from liver, kidney, and testis revealed the presence of HIF-1alpha only in the testis. Immunohistochemistry confirmed this result and revealed that HIF-1alpha was specifically located in interstitial Leydig cells. Electromobility shift assays employing nuclear extracts from the TM3 Leydig cell line revealed that these cells express HIF-1alpha that is capable of binding DNA under normoxic conditions. Furthermore, we found that protein levels can be increased further when the TM3 cells are cultured under hypoxic conditions. Finally, transient transfections of TM3 Leydig cells revealed that the promoter of the mouse 3beta-hydroxysteroid dehydrogenase type 1 (Hsd3b1) gene, which encodes a key enzyme in testosterone production, is a potential target of HIF-1alpha. In conclusion, HIF-1alpha is constitutively present in the Leydig cells of the murine testis, where it potentially regulates Hsd3b1 transcription, and thus male reproductive function.
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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 | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 0.001 |
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".