Spermatogenesis, the process of producing mature spermatozoa from premature germ cells, is critical for the propagation and sustenance of a population. Understanding the mechanisms governing this developmental process is therefore crucial. The hallmark of mammalian spermatogenesis is the dramatic chromatin remodeling that occurs during the various stages of sperm development. During the spermatocytic stages, testis specific histone variants TH2A, H2A.X and TH2B, H2B-RP replace the conventional histones H2A and H2B respectively.  H1 histone is similarly replaced by the variants H1t, H1t2 and HILS1 in the spermatid stages. Furthermore specifically during spermiogenesis, transition proteins (TP1, TP2 and TP4) followed by protamines (P1, P2) replace conventional nucleosomal histones. Our lab is focused on understanding the molecular events that occur and how post-translational modifications on these histone variants aid the aforesaid phenomena.

 

                             

 

Our lab modeled the nucleosome core particle strcuture containing TH2B. Such studies were conducted with an aim to identify the function of germ cell TH2B with respect to nucleosome dynamics.

 

 
 

Pervasive transcription of the genome generates a huge repertoire of non-coding RNAs, some of which are functional while some are not. Annotation and functional characterization of the class of long non-coding RNAs has been an area of interest worldwide.

 
 
 

Our lab has discovered a long intronic non-coding RNA, mrhl (mouse recombination hotspot locus) which is transcribed form the intron14 of phkb gene in mouse chromosome 8 and exhibits tissue-specific expression in adult mouse.

 

 

Mrhl RNA & Wnt Signaling

 

Mrhl RNA negatively regulates Wnt signaling through its protein partner p68 in mouse spermatogonial cells. A hallmark of Wnt signaling activation, translocation of membranous β-catenin to the nucleus, occurs upon mrhl RNA downregulation. Such a phenomenon is brought about by the cytoplasmic translocation of p68 which otherwise is sequestered in the nucleus by mrhl RNA.

 

Genes Regulated by the Physical Association of Mrhl (GRPAM) undergo regulation by the RNA at either the promoter, intragenic or intergenic levels. Treatment of the spermatogonial cells (GC1-Spg) with Wnt3a leads to a downregulation of mrhl RNA by the recruitment of a complex comprising Ctbp1 and HDAcs, thereby blocking meiotic progression.

 

Search for Novel p68 Interacting lncRNAs

    A search for p68 interacting long non-coding RNAs in the human genome has revelaed a novel long non-coding RNA with probable functional implications
Studies are being conducted to understand the role of mrhl RNA in early mammalian development and in identifying its human homolog.
 
 

Astrocytoma is the most common type of brain cancer constituting more than half of all brain tumors. Grade IV Glioblastoma Multiforme (GBM) is a type of Astrocytoma known to be the most rigorous form of cancer with a median survival of 15 months. Previous efforts in the lab involved identifying prognostic markers specifically for Primar Grade IV GBM. Transcriptional profiling through microarray analysis identified two novel markers which were highly overexpressed in primary GBM but not in other forms, Achate-Scute complex like-1 (Drosophila) (ASCL1) and Adipocyte Enhancer binding Protein-1 (AEBP1).

 
 
 

AEBP1

 

Previous work had shown downregulation of Aebp1 led to apoptosis of primary GBM cell lines, U87MG and U138MG. Current work deals with deciphering the mechanism of this cell death. Also looking closer at genomic context as both the cell lines are PTEN negative and PTEN mutations are early driver events to see how this fixates the cells on particular cell death mechanisms.

 

 
  ASCL1 

 

Ascl1 is a basic Helix-Loop-Helix transcription factor, which is involved in various cellular processes like neuronal development and signaling pathways. Transcriptome profiling has shown that its expression plays an important role in glioma and Small Cell Lung Carcinoma.  Current work deals with detailed Ontological analysis  uncovering high quality protein interaction networks of ASCL1 regulated genes which facilitates understanding biological processes driven by ASCL1 target genes .Taking this further on we want to compare ASCL1 regulated gene networks between developmental phases of the brain and glioma.