Positive Regulation of DNA Double Strand Break Repair Activity during Differentiation of Long Life Span Cells: The Example of Adipogenesis

Little information is available on the ability of terminally differentiated cells to efficiently repair DNA double strand breaks (DSBs), and one might reasonably speculate that efficient DNA repair of these threatening DNA lesions, is needed in cells of long life span with no or limited regeneration from precursor. Few tissues are available besides neurons that allow the study of DNA DSBs repair activity in very long-lived cells. Adipocytes represent a suitable model since it is generally admitted that there is a very slow turnover of adipocytes in adult. Using both Pulse Field Gel Electrophoresis (PFGE) and the disappearance of the phosphorylated form of the histone variant H2AX, we demonstrated that the ability to repair DSBs is increased during adipocyte differentiation using the murine pre-adipocyte cell line, 3T3F442A. In mammalian cells, DSBs are mainly repaired by the non-homologous end-joining pathway (NHEJ) that relies on the DNA dependent protein kinase (DNA-PK) activity. During the first 24 h following the commitment into adipogenesis, we show an increase in the expression and activity of the catalytic sub-unit of the DNA-PK complex, DNA-PKcs. The increased in DNA DSBs repair activity observed in adipocytes was due to the increase in DNA-PK activity as shown by the use of DNA-PK inhibitor or sub-clones of 3T3F442A deficient in DNA-PKcs using long term RNA interference. Interestingly, the up-regulation of DNA-PK does not regulate the differentiation program itself. Finally, similar positive regulation of DNA-PKcs expression and activity was observed during differentiation of primary culture of pre-adipocytes isolated from human sub-cutaneous adipose tissue

The nerve supply of the trapeziometacarpal joint.

Ten forearm and hand specimens from fresh cadavers were dissected and examined under magnification for articular branches to the trapeziometacarpal joint arising from the thenar and palmar cutaneous branches of the median nerve, the superficial branch of the radial nerve and the lateral cutaneous nerve of forearm. In all but one specimen the thenar branch of the median nerve sent an articular branch to the trapeziometacarpal joint. Multiple branches from the palmar cutaneous branch of the median nerve, the superficial branch of the radial nerve and the lateral cutaneous nerve of forearm were also found. All these branches need to be divided during a "complete" denervation of the trapeziometacarpal joint.Journal ArticleResearch Support, Non-U.S. Gov'tSCOPUS: ar.jinfo:eu-repo/semantics/publishe

Innervation pattern of the abductor digiti minimi muscle of the hand

WOS: 000178866900009PubMed: 12367541This cadaver study investigated the innervation patterns of the abductor digiti minimi in Guyon's canal. There was only one branch to the abductor digiti minimi in 22 of the 30 specimens. Two branches were found in three hands, and three branches in two. Three other variations were documented