Meiosis is the defining event of spermatogenesis. Spermatocytes undergo meiosis to give rise to round spermatids, which in turn metamorphose to flagellated
spermatozoa that mature in the epididymis. To characterize the dynamics of gene expression during these important stages of spermatogenesis,
undertook transcriptome analysis in >90% pure pachytene spermatocytes and round spermatids, and pure mature sperm of rat by massive parallel
deep sequencing. The study has identified 10,719 total transcripts expressed in meiotic and post-meiotic cells, out of which 7,641 were
present in all the three cell types. Most abundant transcripts were related to gametogenesis in spermatocytes and spermatids, and mitochondrial
energy metabolism in sperm. Importantly, 108 transcripts were specific to spermatocytes, including Cpeb2, Dpf3, H2afy, Haus7, Plcb1, Taf9,
and Tdrd7 strongly linked with meiosis. Similarly, 323 transcripts unique to round spermatids included Arpc5, Apoa1, Cntrob, Dcaf17, Ift88,
and Ly6k that play essential roles in spermiogenesis. Likewise, 178 transcripts unique to sperm included Camta1, Hoxb1, and Prdx6 having
assigned roles in fertility and/or embryonic development. Levels of ~16% transcripts declined from spermatocytes to sperm while two
(Cd300e and Ddx17) increased. New candidate genes with possible roles in meiosis (91), spermiogenesis (298), and sperm function (171), have
been identified. This study has provided new potential targets for contraception and/or treatment of male infertility. (Mol Reprod Dev, 2019;
doi: 10.1002/mrd.23278)
Peripheral blood DNA methylation profiling reveals differential methylation in male infertility
Peripheral blood differential DNA methylation was studied in oligozoospermic infertile men in comparison with normozoospermic fertile controls in a
case-control study. Blood samples were obtained from azoospermic and oligozoospermic infertile patients (n = 6) and normozoospermic fertile controls
(n = 6) in the discovery phase, and oligo/asthenozoospermic infertile men (n = 11) and normozoospermic fertile controls (n = 10) in the validation
phase followed by DNA isolation and methylation analysis. DNA methylation values were analyzed using genome wide methylation 450K BeadChip array,
followed by deep sequencing of selected regions for methylation analysis in the neighborhood regions of differentially methylated CpGs. 329
differentially methylated CpG spots were identified, out of which 245 referred to the genes, representing 170 genes. Deep-sequencing analysis
confirmed the methylation pattern suggested by 450K array. A thorough literature search suggested that 38 genes play roles in spermatogenesis
(PDHA2, PARP12, FHIT, RPTOR, GSTM1, GSTM5, MAGI2, BCAN, DDB2, KDM4C, AGPAT3, CAMTA1, CCR6, CUX1, DNAH17, ELMO1, FNDC3B, GNRHR, HDAC4, IRS2, LIF,
SMAD3, SOD3, TALDO1, TRIM27, GAA, PAX8, RNF39, HLA-C, HLA-DRB6), are testis enriched (NFATC1, NMNAT3, PIAS2, SRPK2, WDR36, WWP2), or show methylation
differences between infertile cases and controls (PTPRN2, RPH3AL). This study conclude a statistically significant correlation between peripheral
blood DNA methylation and male infertility, raising the hope that epigenome-based blood markers can be used for screening male infertility risk.
The study also identified new candidates for spermatogenesis and fertility (FertilSteril. 2019; 112(1): 61-72.e1).
Fig : Heat map showing methylation level (β-value) in cases and controls, bar graph showing the number of hyper- and hypo-methylated CpG spots,
and box whisker plot showing the
average β-value in cases and controls, b) The distribution of DMCs according to the island regions, c) The distribution of DMCs according to the
genomic regions, d) Venn diagram showing the distribution of DMCs in genomic regions with respect to different transcript forms
Genome-wide differential methylation analyses identify methylation signatures of male infertility
Methylation changes in a number of genes have been correlated with reduced sperm count and motility. To discover whether methylation changes in sperm DNA
correlate with infertility, this case-control study used spermatozoal DNA from 38 oligo-/oligoastheno-zoospermic infertile patients and 26
normozoospermic fertile men. Genome-wide methylation analysis was undertaken using 450 K Bead Chip on spermatozoal DNA from six infertile and six fertile
men to identify DMCs. This was followed by deep sequencing of spermatozoal DNA from 32 infertile patients and 20 fertile controls. Loss of spermatogenesis
and fertility was correlated with 1680 differentially-methylatedCpGs (DMCs) across 1052 genes. A total of 1680 DMCs were identified, out of which 1436
were hypermethylated and 244 were hypomethylated. Classification of DMCs according to the genes identified BCAN, CTNNA3, DLGAP2, GATA3, MAGI2 and TP73
among imprinted genes, SPATA5, SPATA7, SPATA16 and SPATA22 among spermatogenesis-associated genes, KDM4C and JMJD1C, EZH2 and HDAC4 among genes which
regulate methylation and gene expression, HLA-C, HLA-DRB6 and HLA-DQA1 among complementation and immune response genes, and CRISPLD1, LPHN3 and CPEB2
among other genes. Genes showing significant differential methylation in deep sequencing, i.e. HOXB1, GATA3, EBF3, BCAN and TCERG1L, are strong
candidates for further investigations. The role of chance was ruled out by deep sequencing of select genes. DMCs can serve as markers for inclusion in
infertility screening panels, particularly those in the genes showing differential methylation consistent with previous studies. The genes validated by
deep sequencing are strong candidates for investigations of their roles in spermatogenesis (Hum Reprod. 2018; 33(12): 2256-2267).
Team Members:
Above Left to Right : Dr Shashi Kumar Gupta, Dr Baisakhi Moharana, Dr Kashif Hanif, Dr Rajendra Singh, Dr Sachin Kumar, Dr Jayanta Sarkar, Dr Amit Lahiri, Dr Aamir Nazir, Dr Rajesh Jha
Below Left to Right : Dr Monika Sachdeva, Dr Manoj Kumar Barthwal, Dr Anila Dwivedi, Dr Gopal Gupta, Dr P.N. Yadav, Dr W Haq, Dr Anil Nilkanth Gaikwad, Dr S.K. Rath, Dr Sarika Singh, Dr Smrati Bhadauria