Acidic nuclear phosphoprotein 32kDa (ANP32)B-deficient mouse reveals a hierarchy of ANP32 importance in mammalian development

The highly conserved ANP32 proteins are proposed to function in a broad array of physiological activities through molecular mechanisms as diverse as phosphatase inhibition, chromatin regulation, caspase activation, and intracellular transport. On the basis of previous analyses of mice bearing targeted mutations of Anp32a or Anp32e, there has been speculation that all ANP32 proteins play redundant roles and are dispensable for normal development. However, more recent work has suggested that ANP32B may in fact have functions that are not shared by other ANP32 family members. Here we report that ANP32B expression is associated with a poor prognosis in human breast cancer, consistent with the increased levels of Anp32b mRNA present in proliferating wild-type (WT) murine embryonic fibroblasts and stimulated WT B and T lymphocytes. Moreover, we show that, contrary to previous assumptions, Anp32b is very important for murine embryogenesis. In a mixed genetic background, ANP32B-deficient mice displayed a partially penetrant perinatal lethality that became fully penetrant in a pure C57BL/6 background. Surviving ANP32B-deficient mice showed reduced viability due to variable defects in various organ systems. Study of compound mutants lacking ANP32A, ANP32B, and/or ANP32E revealed previously hidden roles for ANP32A in mouse development that became apparent only in the complete absence of ANP32B. Our data demonstrate a hierarchy of importance for the mammalian Anp32 genes, with Anp32b being the most critical for normal development.     

Non-genetic contributions of the sperm nucleus to embryonic development

Recent data from several laboratories have provided evidence that the newly fertilized oocyte inherits epigenetic signals from the sperm chromatin that are required for proper embryonic development. For the purposes of this review, the term epigenetic is used to describe all types of molecular information that are transmitted from the sperm cell to the embryo. There are at least six different forms of epigenetic information that have already been established as being required for proper embryogenesis in mammals or for which there is evidence that it may do so. These are (i) DNA methylation; (ii) sperm-specific histones, (iii) other chromatin-associated proteins; (iv) the perinuclear theca proteins; (v) sperm-born RNAs and, the focus of this review; and (vi) the DNA loop domain organization by the sperm nuclear matrix. These epigenetic signals should be considered when designing protocols for the manipulation and cryopreservation of spermatozoa for assisted reproductive technology as necessary components for effective fertilization and subsequent embryo development.     

Breakage-fusion-bridge cycles leading to inv dup del occur in human cleavage stage embryos

Recently, a high incidence of chromosome instability (CIN) was reported in human cleavage stage embryos. Based on the copy number changes that were observed in the blastomeres it was hypothesized that chromosome breakages and fusions occur frequently in cleavage stage human embryos and instigate subsequent breakage-fusion-bridge cycles. In addition, it was hypothesized that the DNA breaks present in spermatozoa could trigger this CIN. To test these hypotheses, we genotyped both parents as well as 93 blastomeres from 24 IVF embryos and developed a novel single nucleotide polymorphism (SNP) array-based algorithm to determine the parental origin of (aberrant) loci in single cells. Paternal as well as maternal alleles were commonly rearranged in the blastomeres indicating that sperm-specific DNA breaks do not explain the majority of these structural variants. The parent-of-origin analyses together with microarray-guided FISH analyses demonstrate the presence of inv dup del chromosomes as well as more complex rearrangements. These data provide unequivocal evidence for breakage-fusion-bridge cycles in those embryos and suggest that the human cleavage stage embryo is a major source of chromosomal disorders.     

Androgenetic alopecia: combing the hair follicle signaling pathways for new therapeutic targets and more effective treatment options

ABSTRACT

Introduction: In the past 30 years, only two drugs have received FDA approval for the treatment of androgenetic alopecia reflecting a lack of success in unraveling novel targets for pharmacological intervention. However, as our knowledge of hair biology improves, new signaling pathways and organogenesis processes are being uncovered which have the potential to yield more effective therapeutic modalities.

Areas covered: This review focuses on potential targets for drug development to treat hair loss. The physiological processes underlying the promise of regenerative medicine to recreate new functional hair follicles in bald scalp are also examined.

Expert opinion: The discovery of promising new targets may soon enable treatment options that modulate the hair cycle to preserve or extend the growth phase of the hair follicle. These new targets could also be leveraged to stimulate progenitor cells and morphogenic pathways to reactivate miniaturized follicles in bald scalp or to harness the potential of wound healing and embryogenic development as an emerging paradigm to generate new hair follicles in barren skin.     

Short limbs,cleft palate,and delayed formation of flat proliferative chondrocytes in mice with targeted disruption of a putative protein kinase gene,Pkdcc (AW548124)

During long bone development, round proliferative chondrocytes (RPCs) differentiate into flat proliferative chondrocytes (FPCs), and then into hypertrophic chondrocytes (HCs). FPCs and HCs support longitudinal bone growth. Here we show that a putative protein kinase gene, Pkdcc (AW548124), is required for longitudinal bone growth. We originally found Pkdcc expressed in the head organizer, but it is also expressed throughout embryogenesis and in various adult tissues. Pkdcc^?/? embryos had no head organizer‐related defects, but showed various morphological abnormalities at birth, including short limbs, cleft palate, sternal dysraphia, and shortened intestine. In the long bones of the limbs, only the mineralized regions were shortened, and the cartilage length was normal. In the humerus, Pkdcc was strongly expressed in the early FPCs, and FPC and HC formation was delayed in Pkdcc^?/? mutants. Together, these data indicate that Pkdcc encodes a protein kinase that is required for the appropriate timing of FPC differentiation. Developmental Dynamics 238:210–222, 2009. © 2008 Wiley‐Liss, Inc.     

Functional morphology of chorioallantoic vascular network in chicken

The formation, development, and reduction of the capillary network in the chicken chorioallantoic membrane on days 7–20 of egg incubation were studied by light and electron microscopy with morphometry. Specific features in the architectonics and structure of the mesodermal large vessels and their connection to the suprachorial capillaries for provision of adequate gas exchange are shown. __________ Translated from Byulleten’ Eksperimental’noi Biologii i Meditsiny, Vol. 142, No. 9, pp. 341–345, September, 2006     

Sonic Hedgehog signaling pathway: from embryology to molecular targeted therapies

It has long been known that the hedgehog signaling pathway is crucial for embryonic development, in both Drosophila and vertebrate systems. During the past few years its implication in carcinogenesis has become clear and today it is acknowledged that this pathway plays a role in the malignant transformation of multiple cell types, either owing to the mutation of some of its components or to its erratic activation. New molecular targeted therapies that inhibit the pathway have shown their unquestionable efficiency in several tumours -among which basal cell carcinoma, medulloblastoma, or pancreatic adenocarcinoma. The assessment of these inhibitors in other types of tumours is currently underway with promising results, suggesting that the Sonic hedgehog signalling pathway may become one of the therapeutic targets of the future.