High impact information on bam

• An apparent null mutation causes abnormal cysts to form containing an excess number of cells that cannot differentiate into gametes. bam function resides within a simple 2.2-kb transcription unit encoding a single 442-amino-acid protein that shows similarity to the product of the ovarian tumor gene [1].
• The specific expression of bam RNA within female cystoblasts suggested that it might be involved in the specific cell-cycle alterations that occur during cystocyte divisions [1].
• bag-of-marbles: a Drosophila gene required to initiate both male and female gametogenesis [1].
• We have shown that bam(-) GSCs can be maintained and promoted to divide in vitro in media containing Dpp [2].
• By using this approach, we demonstrate that bam- cells can populate the gonad and become established as germ-line stem cells [3].

Biological context of bam

• By generating FLP-mediated clones, we demonstrate that both bam and bgcn act autonomously in the germline to restrict proliferation during spermatogenesis [4].
• However, we find that germ cells accumulating in bam or bgcn mutant testes most resemble amplifying germ cells, because they undergo incomplete cytokinesis and progress through the cell cycle in synchrony within a cyst, which are two characteristics of amplifying germ cells, but not of stem cells [4].
• In this paper, we compare the oogenic phenotype of benign gonial cell neoplasm mutations to that of mutations in bam [5].
• We show that the transcriptional silencer element in the bam gene integrates Dpp control of bam expression [6].
• We analyzed the molecular evolution of three genes playing a role during the sperm developmental pathway in Drosophila at an early (bam), a mid (aly), and a late (dj) stage [7].

Anatomical context of bam

• Taken together, our results suggest that bam and bgcn regulate progression through the male germline stem cell lineage by cell-intrinsically restricting the proliferation of amplifying germ cells [4].
• The niche for germline stem cells (GSCs) provides a Dpp/Bmp signal, which is essential for GSC maintenance. bam is both necessary and sufficient for the differentiation of immediate GSC daughters, cystoblasts [8].
• Tumor cells containing the wild-type bam gene under heat shock transcriptional control are able to produce functional oocytes [3].
• This study demonstrates that Bmp signals from the somatic cells maintain GSCs, at least in part, by repressing bam expression in the Drosophila testis. dpp signaling is known to be essential for maintaining GSCs in the Drosophila ovary [9].
• alpha- and beta-Spectrin are major components of a submembrane cytoskeletal network connecting actin filaments to integral plasma membrane proteins [10].

Physical interactions of bam

• Finally, we show that Med and Mad directly bind to the bam silencer in vitro [8].
• These results suggest that RBP9 protein binds to bam mRNA to down regulate BAM protein expression, which is essential for the initiation of cystocyte differentiation into functional egg chambers [11].

Regulatory relationships of bam

• Also, mutations in bgcn dominantly enhance a bam mutant phenotype, further corroborating the interdependence of these two genes' functions [12].
• We demonstrate that one function of Bam is to block Dpp signaling downstream of Dpp receptor activation, thus establishing the existence of a negative feedback loop between the action of the two genes [13].
• Gbb/Bmp signaling is essential for maintaining germline stem cells and for repressing bam transcription in the Drosophila testis [9].
• Pelota controls self-renewal of germline stem cells by repressing a Bam-independent differentiation pathway [14].
• RBP9 appears to stimulate cystocyte differentiation by regulating the expression of bag-of-marbles (bam) mRNA, which encodes a developmental regulator of germ cells [11].

Other interactions of bam

• We demonstrate that Piwi and Bam proteins are expressed independently of each other in reciprocal patterns in GSCs and cystoblasts [15].
• Finally, pum is epistatic to bam, indicating that niche Piwi does not regulate Bam-C through Pum [15].
• Here we investigate how bam and bgcn regulate the male germline stem cell lineage [4].
• The expression of phosphorylated Mad (pMad), a Bmp signaling indicator, is restricted to GSCs and some cystoblasts, which have repressed bam expression [8].
• In marked GSCs mutant for Med and punt, two essential Bmp signal transducers, bam transcription is also elevated [8].

Analytical, diagnostic and therapeutic context of bam

• Five Bam HI segments containing related inverted repeats were isolated from D. melanogaster and analyzed by electron microscopy and restriction mapping [16].

References