Intercellular adhesion molecule-2 is involved in apical ectoplasmic specialization dynamics during spermatogenesis in the rat

Abstract

In this study, we investigated the role of intercellular adhesion molecule-2 (ICAM2) in the testis. ICAM2 is a cell adhesion protein having important roles in cell migration, especially during inflammation when leukocytes cross the endothelium. Herein, we showed ICAM2 to be expressed by germ and Sertoli cells in the rat testis. When a monospecific antibody was used for immunolocalization experiments, ICAM2 was found to surround the heads of elongating/elongated spermatids in all stages of the seminiferous epithelial cycle. To determine whether ICAM2 is a constituent of apical ectoplasmic specialization (ES), co-immunoprecipitation and dual immunofluorescence staining were performed. Interestingly, ICAM2 was found to associate with β1-integrin, nectin-3, afadin, Src, proline-rich tyrosine kinase 2, annexin II, and actin. Following CdCl2 treatment, ICAM2 was found to be upregulated during restructuring of the seminiferous epithelium, with round spermatids becoming increasingly immunoreactive for ICAM2 by 6–16 h. Interestingly, there was a loss in the binding of ICAM2 to actin during CdCl2-induced germ cell loss, suggesting that a loss of ICAM2–actin interactions might have facilitated junction restructuring. Taken collectively, these results illustrate that ICAM2 plays an important role in apical ES dynamics during spermatogenesis.

Intercellular adhesion molecule 1: Recent findings and new concepts involved in mammalian spermatogenesis

“…Bar in (a), 100 μm; bar in (a), inset, 35 μm. These results are in agreement with a previously published report [212]. …”

“…3) [212]. The presence of ICAM2 at the apical ectoplasmic specialization was substantiated by colocalization and/or co-immunoprecipitation experiments when ICAM2 was found to associate with apical ectoplasmic specialization constituent proteins such as β1-integrin, nectin 3 and actin [212]. Interestingly, ICAM2 did not localize to the BTB (Fig.…”

“…By immunohistochemistry, ICAM2 localized largely to Sertoli-germ cell contact sites, associating with the apical ectoplasmic specialization (Fig. 3) [212]. The presence of ICAM2 at the apical ectoplasmic specialization was substantiated by colocalization and/or co-immunoprecipitation experiments when ICAM2 was found to associate with apical ectoplasmic specialization constituent proteins such as β1-integrin, nectin 3 and actin [212].…”

Genome-Wide Association Study for Indicator Traits of Sexual Precocity in Nellore Cattle

“…Several other genes related to testicular growth and development were identified. Many of these genes are also directly involved in spermatogenesis, such as the HILS1 gene that remodels chromatin during gamete production [ 50 ], the KAT7 and ICAM2 genes expressed in Sertoli cells [ 51 , 52 ], the TCAM1 gene expressed in spermatocytes [ 53 ], the SLC26A3 gene that is essential for sperm capacitation [ 54 ], and the RAD18 gene that plays a crucial role in genome maintenance during sperm production [ 55 ]. Other important genes are the FBXO32 (Chr14/17.83–18.51Mb) and EBF2 (Chr08/73.91-75Mb) genes related to infertility and hypogonadism in men, respectively [ 56 , 57 ], and the GH1 gene (Chr19/48.69–49.21Mb) associated with seminal characteristics and sexual behavior in cattle [ 58 ].…”

The Sertoli cell: one hundred fifty years of beauty and plasticity

“…This exclusive structure displayed its plasticity by also appearing as a Sertoli cell component of the Sertoli‐spermatid germ cell junctional attachment site, forming apical ectoplasmic specializations facing the germ cell at the edge of the very narrow cytoplasmic arms that surrounded forming spermatid heads (Fig. ) (Xiao et al ., ; Gungor‐Ordueri et al ., ; Hess & Vogl, ; Li et al ., ; Mruk & Cheng, ). The basal ES is part of the blood–testis barrier, along with the proteins and structures associated with the junctional complex (tight, gap and desmosome).…”