Quantification of protamines 1, 2 andtransition protein 2 transcript contents inhuman spermatozoa and their relation withsperm morphology
Introduction: Several studies have shown thatmore than 5000 mRNAs exist in human ejaculatedspermatozoa. Protamine transcripts are composedmostly of mRNA content of mature Sperm.Protamines, the main nuclear proteins of humansperm, have important role in normal morphologyand function of mature Sperm. Considering thestructural role of protamine in normal morphologyof sperm head and abundant presence of theirtranscripts in mature sperm, this case-control studywas designed to quantify and compares the level ofTNP2, PRM1 and PRM2 transcripts in maturespermatozoa of normozoospermic andteratozoospermic men.Materials and Methods: Semen sample of 50normozoospermic and 104 teratozoospermic men,attending Avicenna Infertility Clinic, wereanalysed according to WHO guideline. Eachsemen sample was divided into two aliquots usedfor sperm chromatin staining assay (CMA3, ABstaining methods) and RNA content RNA wasisolated from spermatozoa and then reversetranscribedinto cDNA. Using real-time RT-PCR,the contents of TNP2, PRM1 and PRM2 transcriptsof sperm were assessed in two groups.Results: PRM1, PRM2 and TNP2 transcript wasquantified in normozoospermic (PRM1:7/49×109±5/17 ×1010, PRM2: 2/70×107 ±1/90 ×108and TNP2: 4/84×106±3/42×107) andteratozoospermic men (PRM1:2/20×109±2/21×1010, PRM2: 9/21×10-1±7/92 ×10TNP2: 1/75×1010±1/33 ×108). There wassignificant positive correlation between level ofTNP2 transcripts and sperms head defects (r=0.354, p=0.012). Significant negative correlationwas found between ratio of PRM1/PRM2transcripts and sperm tail defects (r=-0.846,p=0.008) in normozoospermic men as compared toteratozoospermic men.Conclusion: Significant correlation betweenTNP2, PRM1 and PRM2 transcripts and spermmorphology indicates that abnormal morphologyof sperm may be the result of defectivereplacement of histones by TNP1 and TNP2 andsubsequently PRM1 and PRM2 for normalchromatin packaging and normal morphology. Ourresult also reveal the potential applications ofmRNA contents of mature sperm as a diagnostictools in molecular evaluation of human spermfunctions.