In Vivo Knockdown of the IP3R1 Calcium Channel Disrupts ER and Actin Morphology, as well as TBC Bulb Maturation in the Apical Processes of Sertoli Cells in Rat Testes
Bibliographic record
Abstract
Spermatogenesis is the process by which sperm cells are produced, but at one phase of this process, late stage spermatids are temporarily attached to the apex of Sertoli cells in the seminiferous epithelium. Late spermatids are anchored by large adhesion like junction complexes termed ‘ectoplasmic specializations’ (ESs) that are proposed to be disassembled by novel endocytic structures only found in mammalian Sertoli cells, called ‘tubulobulbar complexes’ (TBCs). Both ESs and TBCs are heavily actin related, with parallel actin arrays and dendritic actin networks respectively being hallmarks of their identities. The endoplasmic reticulum (ER) in the Sertoli cell apical processes surrounding the late spermatids forms an extensive and continuous network. Cisternae of this network form part of the structure of the ESs, participate in a membrane contact site with the bulbs of TBCs, and have a parallel alignment with the surrounding Sertoli cell plasma membrane. Previously, we've localized the IP3R calcium channel to the TBC bulb‐ER contacts as well as other calcium exchange machinery to various parts of the ER in the apical process. Calcium release and exchange have been implicated in processes related to both actin dynamics as well as in fusion and acidification of endocytic components such as endosomes. We've proposed that calcium exchange may be a crucial mechanism in regulating both the actin networks of ESs and TBCs, as well as in facilitating the maturation and fusion of TBC bulbs as they develop into putative endosomes. If calcium exchange from the ER is responsible for regulating the local actin networks and maturation of endocytic components in the apical process, then knocking down the primary calcium release channel of the ER should alter local actin and TBC bulb morphology. To test this, we injected the testes of Sprague Dawley rats with siRNAs against IP3R1 (ITPR1) and collected tissues at 1 day, 2 day, and 3 days post injection and processed the tissues for either western blot, immunofluorescence, or electron microscopy. ITPR1 siRNA treated tissues showed significant morphological alterations to the ER, actin, and TBC bulbs in the apical processes of late spermatids compared to controls. This data supports the hypothesis that ER calcium exchange is an integral component to actin dynamics and TBC bulb maturation in the apical processes of Sertoli cells. Support or Funding Information Natural Sciences and Engineering Research Council of Canada (NSERC) Discovery Grant awarded to AWV; Alexander Graham Bell Scholarship (NSERC) awarded to AA This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal .
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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 | 0.001 |
| 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 | 0.001 |
| Insufficient payload (model declined to judge) | 0.003 | 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".