Expression of P57kip2 in Germ Cells and Leydig Cells in Human Testis

Abstract

kip2 , a KIP family cyclin-dependent kinase (Cdk) inhibitor, blocks the cell cycle by acting on multiple cyclin-Cdk complexes. To investigate the role of p57 kip2 in human fertility, the expression of p57 kip2 was investigated in testes from normal and obstructive azoospermic male patients who were positive for p57 kip2 mRNA. In the seminiferous tubule, strong immunoreactivity of p57 kip2 was found in nuclei of early spermatocytes, but not in the spermatogonia. The p57 kip2 immunoreactivity in spermatocytes was markedly heterogeneous. Preleptotene spermatocytes showed strong p57 kip2 immunoreactivity, but no visible signal was found in late pachytene spermatocytes. Nuclei of the elongating spermatids was also positive for p57 kip2 immunoreactivity. Taken together, this suggests that p57 kip2 may play a role in the regulation of meiotic progression of early spermatocytes and cell cycle arrest and differentiation of spermatids. p57 kip2 immunoreactivity was found in the perinuclear region of the peritubular cells, but not in the Sertoli cells. In Leydig cells, moderate immunoreactivity of p57 kip2 was largely found in the cytoplasm, suggesting the noble function of p57 kip2 in the differentiation of adult Leydig cells.

Evidence for the involvement of NGF in human sperm motility

“…An analysis of the stage-specific expression of NGF during the cycle of the seminiferous epithelium in the rat revealed NGF mRNA and protein at all stages of the cycle. A quantitative determination by immunoassay of NGF in human testis revealed the presence of 5.44 ng of NGF per g wet weight [14,15]. NGF remains associated with spermatozoa throughout their maturation in the epididymis, and further peptides may be absorbed to the sperm surface from sources in the epididymal epithelium.…”

Surfing the wave, cycle, life history, and genes/proteins expressed by testicular germ cells. Part 1: Background to spermatogenesis, spermatogonia, and spermatocytes

“…In human testis, p57kip2 is strongly immunoreactive in PL spermatocytes but not in pachytene spermatocytes. P57kip2 may regulate the meiotic progression of early spermatocytes and be involved in cell cycle arrest and differentiation of spermatids (Kim and Gye, 2004;Kim et al, 2006). NUMA1 [ID: T1-153] is a nuclear protein that accumulates at the spindle poles during mitosis.…”

p57KIP2: “Kip”ing the Cell under Control

“…Most of the data have been obtained from rodents (14,(38)(39)(40)(41)(42)(43)(44) and only sporadically in humans (11,12,44,45). Specifically, the highest levels and most widespread tissue localization were observed during organogenesis.…”

“…p57 KIP2 and p27 KIP1 cooperate in a temporal manner for pituitary development; p57 KIP2 promotes cell cycle exit of progenitors, whereas p27 KIP1 prevents cell cycle reentry (164). p57 KIP2 is also implicated in hepatocyte maturation (40), T-lymphocyte cell development (165), spermatogenesis and Leydig cell development (45), hematopoiesis and hematopoietic stem cell cycle arrest (93,166), chondrocyte differentiation (133,167), and in adrenal cortex development (168).…”