To achieve and maintain fertility, the adult mammalian testis produces many generations of sperm. While testicular integrity is established in the fetus and develops further in juvenile life, sperm production does not ensue until much later in life, following the onset of puberty. Signals from the transforming growth factor-beta superfamily of proteins are vital for governance of testis development and spermatogenesis, and this review discusses our current understanding of the mechanisms and processes in which they have been implicated with a focus on the fetal and juvenile testis.

Testicular development is governed by the combined influence of hormones and proteins, including FSH, inhibins, activins and follistatin (FST). This study documents the expression of these proteins and their corresponding mRNAs, in testes and serum from mice aged 0 through 91 days post partum (dpp), using real-time PCR, in situ hybridisation, immunohistochemistry, ELISA and RIA. Serum immunoactive total inhibin and FSH levels were negatively correlated during development, with FSH levels rising and inhibin levels falling. Activin A production changed significantly during development, with subunit mRNA and protein levels declining rapidly after 4 dpp, while simultaneously levels of the activin antagonists, FST and inhibin/activin b C , increased. Inhibin/activin b A and b B subunit mRNAs were detected in Sertoli, germ and Leydig cells throughout testis development, with the b A subunit also detected in peritubular myoid cells. The a, b A , b B and b C subunit proteins were detected in Sertoli and Leydig cells of developing and adult mouse testes. While b A and b B subunit proteins were observed in spermatogonia and spermatocytes in immature testes, b C was localised to leptotene and zygotene spermatocytes in immature and adult testes. Nuclear b A subunit protein was observed in primary spermatocytes and nuclear b C subunit in gonocytes and round spermatids. The changing spatial and temporal distributions of inhibins and activins indicate that their modulated synthesis and action are important during onset of murine spermatogenesis. This study provides a foundation for evaluation of these proteins in mice with disturbed testicular development, enabling their role in normal and perturbed spermatogenesis to be more fully understood.

Integrin-linked kinase (ILK) and p38(MAPK) are protein kinases that transduce extracellular signals regulating cell migration and actin cytoskeletal organization. ILK-dependent regulation of p38(MAPK) is critical for mammalian kidney development and in smooth muscle cell migration, however, specific p38 isoforms has not been previously examined in ILK-regulated responses. Signaling by ILK and p38(MAPK) is often dysregulated in bladder cancer, and here we report a strong positive correlation between protein levels of ILK and p38β, which is the predominant isoform found in bladder cancer cells, as well as in patient-matched normal bladder and tumor samples. Knockdown by RNA interference of either p38β or ILK disrupts serum-induced, Rac1-dependent migration and actin cytoskeletal organization in bladder cancer cells. Surprisingly, ILK knockdown causes the selective reduction in p38β cellular protein level, without inhibiting p38β messenger RNA (mRNA) expression. The loss of p38β protein in ILK-depleted cells is partially rescued by the 26S proteasomal inhibitor MG132. Using co-precipitation and bimolecular fluorescent complementation assays, we find that ILK selectively forms cytoplasmic complexes with p38β. In situ proximity ligation assays further demonstrate that serum-stimulated assembly of endogenous ILK-p38β complexes is sensitive to QLT-0267, a small molecule ILK kinase inhibitor. Finally, inhibition of ILK reduces the amplitude and period of serum-induced activation of heat shock protein 27 (Hsp27), a target of p38β implicated in actin cytoskeletal reorganization. Our work identifies Hsp27 as a novel target of ILK-p38β signaling complexes, playing a key role in bladder cancer cell migration.