The International Journal of Developmental Biology

ABSTRACT

Based on observations of in vivo morphogenesis, differentiation is expected to be regulated by mechanical cues. However, the detail mechanisms remain largely unknown. A previous study using human pluripotent stem cells (hPSCs) demonstrated that neural plate border (NPB) specification was enhanced by mechanical force. However, it is unknown whether mechanical force is also involved in the specification of the preplacodal ectoderm (PPE), which is derived from the NPB. Here, we verified the validity of the PPE induction method in stretch chambers, and conducted the stretching stimuli experiments. When repetitive stretching stimuli were applied from Day 2 to 10 or Day 2 to 7, expression of the PPE marker SIX1 was increased. However, this increase was not observed when the stimuli were applied from Day 5 to 10, suggesting there is a critical period of sensitivity to mechanical forces. Immunofluorescent staining revealed lower active β-catenin signals in the cell sheet in the stretched samples compared to those in the controls, suggesting a negative correlation between stretching stimuli and Wnt signaling. Our finding suggests that mechanical force is important in PPE...

ABSTRACT

Recent studies suggest that tail regeneration in lizards begins with a tumor-like stage usually termed regenerative blastema. Oncogenes and tumor suppressors are activated in blastema cells, resulting in a balanced cell proliferation that does not turn the blastema into a tumor. This outgrowth elongates forming new tissues and tail. We previously showed that physiological extracts from regenerating lizard tissues inhibit the growth of cancer cells in vitro within 2-4 days of administration, demonstrating that the growing lizard blastema contains regulatory molecules which can also influence human cancer cells. The molecules responsible for this inhibition were not identified in that initial study. In the present experimental study, after specific extractions of RNAs and/or proteins from the regenerating tail of lizard, we have confirmed the inhibition of breast cancer cell vitality in vitro within 2-3 days from their addition to the culture medium. Proteolysis or heat denaturation of proteins abolished the inhibitory effect. RNA delivered to breast cancer cells in vitro through lipid vesicles (liposomes) showed the highest inhibition of cancer cells...

ABSTRACT

The enhancer threshold is defined as the minimum concentration of transcription factors (TFs) required to elicit an enhancer response in a given time and space. Here, evidence is presented that the enhancer threshold is relative to promoter strength in the early Drosophila embryo. The apparently inactive even-skipped (eve) minimal stripe element (MSE), in which a single Hunchback (Hb)-binding site is deleted, is functionally complemented by the hsp70 promoter in transgenic embryos. Forced pause release of RNA polymerase II (Pol II) and transcription bubble assays show that both eve and heat shock protein 70 (hsp70) promoters exhibit paused Pol II. However, bioinformatics analyses and transient transfection assays indicate that the strength of the hsp70 promoter is much stronger than that of the eve promoter. Consistently, inactive MSE function is also restored by promoters stronger than the eve promoter. It is conceivable that the functional complementarity between enhancer and promoter strengths defines the enhancer threshold, thus determining whether a genomic locus acts as an enhancer for...

ABSTRACT

The transcription factor GATA4 is found in Sertoli and Leydig cells, whereas SOX9 is exclusive to Sertoli cells, being both factors essential for the normal development of murine and human fetal testis. In turn, the steroidogenic acute regulatory protein (STAR) is specifically expressed in Leydig cells. Nevertheless, the function of STAR, GATA4 and SOX9 in peripubertal, adolescent and adult testes in Klinefelter syndrome and azoospermic patients remains poorly understood. To characterize the developmental expression of STAR, GATA4 and SOX9 in human testicular somatic cells, we performed immunofluorescence using fetal, peripubertal, adolescent and adult testes. Our findings demonstrate that STAR is absent in early fetal stages, but present in Leydig cells from 12 weeks of gestation, as well as in peripubertal, adolescent and adult Klinefelter patients, in the adult testis with idiopathic azoospermia and in men showing normal spermatogenesis. GATA4 was expressed in both Sertoli and Leydig cells during all the studied developmental stages and in peripubertal, adolescent and adult patients with and without spermatogenesis. SOX9 was mainly expressed in Sertoli cells...

ABSTRACT

Toll-Like Receptor 7 (TLR7) is recognized for its role in immune responses, particularly in detecting viral RNA. However, emerging evidence suggests that TLR7 may also contribute to ocular development. In this study, we assessed the expression pattern of TLR7 in various CD-1 mouse eye compartments during critical developmental stages, from embryonic day 12 to 16, as well as in adult tissues such as the cornea, pigmented epithelium, neural retina and lens. Our findings reveal a region-specific and time-dependent expression of TLR7, suggesting that it may play a role in the morphogenetic processes that shape the eye during intrauterine development.