Biomedical subjects

Meenu Kapoor

Publications and source records attributed to Meenu Kapoor.

4 recordsLinked to original sources

PubMed2026

Insights into the regulatory roles of LIKE-HETEROCHROMATIN PROTEIN 1 and its targeting to different nuclear compartments modulated by NLS and the conserved domains in the moss Physcomitrium patens.

LIKE-HETEROCHROMATIN PROTEIN 1 (LHP1) is a polycomb group protein that exists in shared multiprotein complexes that harbor core PRC1 and PRC2 proteins. We previously characterized LHP1 in the moss Physcomitrium patens and showed that its function is closely linked with regulation of RNA metabolic processes and the protein is distributed in the nucleoplasm, subnuclear foci, and the nucleolus. To gain mechanistic insight into PpLHP1-mediated gene regulation, in the present study genome-wide changes in transcript profiles of genes affected by loss-of-PpLHP1 function were studied using pplhp1 mutants. RNA-seq analysis reveals a key role for PpLHP1 in regulating energy metabolic processes, ribosome-related pathways, stress signaling/responsive pathways, DNA transcription, etc. ChIP using H3K27me3 coupled with qRT-PCR shows that PpLHP1 suppresses transcription at 5S rRNA promoters and the untimely activation of genes regulating developmental transition by PRC2-dependent and independent mechanisms. To study how PpLHP1 finds its targets in different nuclear compartments and the roles of the multiple NLSs and the conserved domains in guiding the protein, FRAP and deletion studies were performed. These show that PpLHP1 is a mobile protein that diffuses freely in the nucleoplasmic space showing different retention times in the nucleolus, nucleoplasm, and the subnuclear foci indicating its differential affinity for targets at these sites. Expression of PpLHP1 fragments in protonema cells and its subsequent visualization under confocal microscope shows that localization of PpLHP1 to different subnuclear compartments is guided by the monopartite NLS2, CD, and CSD that also play a key role in promoting subnuclear foci formation in the nucleoplasm.

Bryopsida↗

PubMed2005

Transgene-triggered, epigenetically regulated ectopic expression of a flower homeotic gene pMADS3 in Petunia.

pMADS3 is a class C floral homeotic gene of Petunia that is specifically expressed in stamens and carpels of developing flowers. We previously reported that introduction of a part of the pMADS3 genomic sequence silenced endogenous pMADS3 (sil-pMADS3) in transgenic Petunia hybrida. Here we report that introduction of the same sequence triggers ectopic expression of endogenous pMADS3 in sepals, petals and leaves (ect-pMADS3), accompanied by homeotic conversion of the floral organs and altered leaf morphology similar to that of an Arabidopsis curly leaf mutant. The occurrence of the ect-pMADS3 phenotype depended on the presence of pMADS3 intron 2 in the transgenes. Occasionally, sil-pMADS3 and ect-pMADS3 phenotypes somatically interconverted. Some T1 progeny inherited their parent's pMADS3 expression pattern, while others switched from sil-pMADS3 to ect-pMADS3 and vice versa. Both phenotypes occasionally occurred even after the transgenes were segregated away. RT-PCR analyses of ectopically expressed pMADS3 transcripts indicated that two pMADS3 alleles were often differently regulated. Furthermore, reciprocal crosses with untransformed Petunia indicated that pMADS3 alleles other than the one ectopically expressed in T0 plants were sometimes expressed ectopically in T1 plants: the paramutation-like transmission of epigenetic regulation between alleles. We detected in the transformants aberrant transcripts, including sense and antisense pMADS3 intron 2 sequences of heterogeneous molecular sizes, irrespective of the pMADS3 phenotypes. We speculate on possible molecular mechanisms underlying these epigenetic phenomena.

Chromosome Mapping↗

PubMed2003

Asymptomatic essential thrombocythemia: a case report.

Essential thrombocythemia (ET) is a clonal disorder of unknown etiology involving multipotent hematopoietic progenitor cell and belongs to the spectrum of chronic myeloproliferative disorders (CMPD). It is rarest of the CMPD with no case reported from India. The case being presented was detected incidentally during routine investigations in an adult female who presented with mild abdominal discomfort.

Adult↗

PubMed2002

Role of petunia pMADS3 in determination of floral organ and meristem identity, as revealed by its loss of function.

pMADS3, a petunia class C gene, is the candidate homologue of Arabidopsis AGAMOUS (AG), which is involved in the specification of stamens and carpels. We report the characterization of loss-of-function phenotype of pMADS3 that resulted from silencing of this gene. Silencing of pMADS3 resulted in homeotic conversion of stamens into petaloid structures, whereas the carpels were only weakly affected. Ectopic secondary inflorescences emerged from the interstamenal region in the third whorl, which is unique and has not been reported for any class C gene of other plant species. Third-order inflorescences emerged at corresponding positions in the third whorl of inner flowers of secondary inflorescences, indicating reiterative conversion of parts of the floral meristem into inflorescence meristem. On the basis of phenotypic analysis of the pMADS3-silenced plants, we propose that pMADS3 is involved in determination of floral organ and floral meristem identity in petunia. Two hybrid studies in yeast showed that PMADS3 protein interacted specifically with FBP2, a candidate homologue of Arabidopsis SEPALLATA3 (SEP3). The evidence presented here suggest that a complex involving PMADS3 and FBP2 is responsible for specification of organ identity in the third whorl.

Flowers↗