Knockdown of IP3R1 Disrupts TBC-ER Contact Sites and the Morphology of Apical Processes Encapsulating Late Spermatids.

Knockdown of IP3R1 Disrupts TBC-ER Contact Sites and the Morphology of Apical Processes Encapsulating Late Spermatids. Biol Reprod. 2020 May 14;: Authors: Adams A, Vogl W Abstract Tubulobulbar complexes (TBCs) internalize intercellular junctions during sperm release. One of the characteristic features of TBCs is that they form 'bulbs' or swollen regions that have well defined membrane contact sites (MCS) with adjacent cisternae of endoplasmic reticulum. Previously, we have localized the IP3R calcium channel to the TBC bulb-ER contacts and have hypothesized that fluctuations in local calcium levels may facilitate the maturation of TBC bulbs into putative endosomes, or alter local actin networks that cuff adjacent tubular regions of the TBCs. To test this, we injected the testes of Sprague Dawley rats with siRNAs against IP3R1 and processed the tissues for either western blot, immunofluorescence, or electron microscopy. When compared to control testes injected with non-targeting siRNAs, Sertoli cells in knocked-down testes showed significant morphological alterations to the actin networks including a loss of TBC actin and the appearance of ectopic para-crystalline actin bundles in Sertoli cell stalks. There also was a change in the abundance and distribution of TBC-ER contact sites and large internalized endosomes. This disruption of TBCs resulted in delay of the withdrawal of apical processes away from spermatids and in spermiation. T...
Source: Biology of Reproduction - Category: Reproduction Medicine Authors: Tags: Biol Reprod Source Type: research